JP2020152364A - Transmission structure and work vehicle - Google Patents

Abstract

To provide a transmission structure which can expand a change width of a shift output shaft without occurrence of sudden rotational speed change in the shift output shaft which is operatively rotationally driven by output of an HMT structure.SOLUTION: A change gear ratio of input side first and second transmission mechanisms is so set as to be same at the time when a rotational speed of a planetary second element is in a first transmission state and an HST output is so made as to be a second HST speed and at the time in a second transmission state, and to be same at the time when a rotational speed of a planetary first element is in the second transmission state and the HST output is so made as to be the second HST speed and at the time in the first transmission state. A change gear ratio of output side first and second transmission mechanisms is so set that a rotational speed displayed on a shift output shaft is same in the first and second transmission states when the HST output is so made as to the second HST speed.SELECTED DRAWING: Figure 2

Description

The present invention relates to a transmission structure including a hydrostatic / mechanical continuously variable transmission mechanism (HST) and a hydrostatic / mechanical continuously variable transmission structure (HMT structure) having a planetary gear mechanism, and a work vehicle having the transmission structure.

The HMT structure, which is a combination of the HST and the planetary gear mechanism, is suitably used for the traveling system transmission path of a work vehicle such as a combine harvester or a tractor, and further expands the variable speed range of the work vehicle having the HMT structure. Various configurations have been proposed for this purpose.

For example, in Patent Document 1 below, the variable range of vehicle speed is expanded by arranging an HMT structure and a multi-stage transmission structure having three speed stages of low speed, medium speed, and high speed in series in the traveling system transmission path. The combine is disclosed.
However, the configuration described in Patent Document 1 is intended to perform the shifting operation of the multi-stage shifting structure in advance before the start of vehicle traveling, and the shifting operation of the multi-stage shifting structure is performed while the vehicle is traveling. And the following inconveniences occur.

Regarding this point, the HMT structure is operated in a state where the multi-stage speed change structure is engaged with the low speed stage to increase the traveling vehicle speed, and when the traveling vehicle speed reaches a predetermined vehicle speed, the multi-stage speed change structure is changed from the low speed stage. An example of shifting to the medium speed stage will be described.

In this case, when the output of the HMT structure reaches the maximum speed or the vicinity of the maximum speed in the low speed stage engaged state of the multi-speed structure, the output of the HMT structure is maintained at the maximum speed or the vicinity of the maximum speed. The multi-speed structure will be changed from the low speed to the medium speed, and a large change in vehicle speed will occur at the time of shifting, resulting in poor riding comfort and an excessive load on the traveling system transmission path.

In this regard, Patent Document 2 below describes a transmission for a work vehicle in which an HMT structure and a multi-speed transmission structure are arranged in series in a traveling system transmission path, and even if the multi-speed transmission structure is changed while the vehicle is traveling. , A transmission for a work vehicle that can suppress a change in vehicle speed and prevent an excessive load from being applied to a traveling system transmission path has been proposed.

Specifically, the transmission described in Patent Document 2 includes an HMT structure having an HST and a planetary gear mechanism, a multi-speed transmission structure for multi-speeding the output of the HMT structure, and a lock-up mechanism.

The HST includes a pump that inputs rotational power from a drive source, a motor that is fluidly driven by the pump, and an output adjusting member that changes the volume of the pump and at least one of the motors (for example, a pump). The output adjusting member operates according to the amount of operation of the speed change operating member that is artificially operated, and the rotation speed of the motor shifts steplessly according to the operation amount.

The planetary gear mechanism is configured to combine the rotational power from the HST input to the sun gear and the rotational power from the drive source input to the carrier and output them from the internal gear toward the multi-speed transmission structure. Has been done.
The lockup mechanism is configured to synchronously rotate the carrier and the internal gear only during the shifting period of the multi-speed structure.

The speed change operation of the transmission described in Patent Document 2 will be described by exemplifying a case where the multi-speed speed change structure is increased from the first speed stage to the second speed stage.

When the speed change operating member is operated in the speed increasing direction within the first speed stage operation range, the output adjusting member has an HST output from the first HST speed (for example, the maximum speed on the reverse side) to the second HST speed (for example, forward rotation). It is moved in the direction of shifting to the side maximum speed).

Then, when the speed change operation member is operated to the boundary position between the first speed stage operation range and the second speed stage operation range, the output adjustment member moves to the second HST speed position (for example, the maximum tilt position on the normal rotation side). ), The HST output is in the state of the second HST speed (for example, the maximum speed on the forward rotation side).
This state is the maximum speed output state of the HMT structure in the first speed engagement state of the multi-speed structure.

When the speed change operating member is operated into the second speed stage operation range beyond the boundary position between the first speed stage operation range and the second speed stage operation range, the multi-speed speed change structure responds to the first speed. The speed is increased from the stage to the second speed.

In the shift period of the multi-speed structure, as described above, the internal gear and the carrier are connected by the lock mechanism and rotated synchronously.
As a result, the rotational power synchronized with the rotational power from the drive source input to the carrier is transmitted to the multi-speed transmission structure that inputs the rotational power from the internal gear.

On the other hand, during the shift period of the multi-speed shift structure, the output adjusting member is in a free state in which the linkage with the shift operation member is released.
Therefore, the motor shaft and the sun gear that are operatively connected to each other are connected by the lock mechanism and are defined by the rotation speeds of the internal gear and the carrier that are synchronously rotated by the rotational power from the drive source. It is rotated at the same rotation speed (hereinafter referred to as the rotation speed during the shift period).

As a result, the output adjusting member is at a position where the HST output corresponding to the shift period rotation speed of the sun gear appears from the second HST speed position (for example, the maximum tilt position on the normal rotation side) (hereinafter, shift period reference position). It is returned to the direction of the first HST speed position.

After that, when the speed change operating member is operated in the speed increasing direction within the second speed stage operation range, the output adjusting member is operated from the shift period reference position to the second HST speed position, and the motor shaft rotates. The speed is increased.
As a result, the rotational speed of the sun gear, which is rotationally driven by the HST output from the motor shaft, is increased, and the rotational speed of the internal gear is increased.

As described above, in the transmission described in Patent Document 2, the rotational power input to the sun gear during the speed change operation of the multi-stage speed change structure is from the second HST speed (for example, the maximum speed on the forward rotation side). The speed is reduced to the rotation speed during the shift period.

The transmission described in Patent Document 2 having such a configuration is useful in that the change width of the traveling vehicle speed at the time of shifting of the multi-speed shifting structure can be suppressed as compared with the configuration described in Patent Document 1. However, there still remains a large change in the traveling vehicle speed at the time of shifting the multi-speed transmission structure.

Japanese Patent No. 5822761 Japanese Patent No. 4162328

The present invention has been made in view of the prior art, and is a transmission structure having an HST and a planetary gear mechanism and a speed change output shaft operatively driven by an output unit of the planetary gear mechanism, and the speed change output. One object of the present invention is to provide a transmission structure capable of expanding the shift width of the shift output shaft without causing a sudden change in the rotational speed of the shaft.
Another object of the present invention is to provide a work vehicle having the transmission structure.

In order to achieve the above one object, the first aspect of the present invention is to apply the rotational power operatively input from the drive source to the pump shaft at least from the first HST speed to the second HST speed according to the operating position of the output adjusting member. HST that shifts steplessly to the rotational power between and outputs from the motor shaft, a planetary gear mechanism that has first to third elements and the third element acts as an input unit for HST output, and a speed change output shaft. The input side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at the input side first gear ratio, and the second transmission side at the input side second gear ratio to transmit the rotational power of the drive source to the first element. The input side second transmission mechanism capable of transmitting the operation to the element, and the input side first clutch mechanism and the input side second clutch mechanism that engage and disengage the power transmission of the input side first transmission mechanism and the input side second transmission mechanism, respectively. The output side first transmission mechanism capable of transmitting the rotational power of the second element to the shift output shaft at the output side first gear ratio, and the rotational power of the first element at the output side second gear ratio. The output side first clutch mechanism and the output side second that engage and disengage the power transmission of the output side first transmission mechanism and the output side second transmission mechanism, respectively, which can transmit the operation to the speed change output shaft. A clutch mechanism, a shift operation member, an HST sensor that directly or indirectly detects the shift state of the HST, an output sensor that directly or indirectly detects the rotation speed of the shift output shaft, and the output adjustment member. The input side first and second clutch mechanisms and a control device for controlling the operation of the output side first and second clutch mechanisms are provided, and the control device is used for detection signals of the HST sensor and the output sensor. Based on this, when the rotation speed of the speed change output shaft is lower than the predetermined switching speed, the input side and the output side first clutch mechanism are engaged and the input side and the output side second clutch mechanism are disconnected. By doing so, the first transmission state in which the first element acts as an input unit of the reference power operatively transmitted from the drive source and the second element acts as an output unit of the combined rotational power is revealed. At the same time, the output adjusting member is operated so that the HST output shifts from the first HST speed to the second HST speed in response to the speed increasing operation of the speed change operating member, while the rotation speed of the speed change output shaft changes speed. In the above high-speed state, the first element acts as an output unit by disengaging the first clutch mechanism on the input side and the output side and engaging the second clutch mechanism on the input side and the output side. Moreover, the second element is used as a reference power input unit. While displaying the second transmission state to be acted on, the output adjusting member is operated so that the HST output shifts from the second HST speed to the first HST speed in response to the speed increasing operation of the speed change operating member, and the input is The side first and second gear ratios are the rotational speed of the second element when the HST output is set to the second HST speed in the first transmission state and via the input side second transmission mechanism in the second transmission state. The rotational speed of the first element and the first transmission state when the rotational speed of the second element due to the rotational power transmitted is the same and the HST output is the second HST speed in the second transmission state. At this time, the rotational speed of the first element due to the rotational power transmitted via the input side first transmission mechanism is set to be the same, and the output side first and second gear ratios are HST. Provided is a transmission structure in which the rotational speeds appearing on the speed change output shaft when the output is set to the second HST speed are set to be the same in the first and second transmission states.

Further, in order to achieve the above-mentioned one object, in the second aspect of the present invention, the rotational power operatively input from the drive source to the pump shaft is applied from at least the first HST speed according to the operating position of the output adjusting member. HST that continuously shifts to rotational power between 2 HST speeds and outputs from the motor shaft, a planetary gear mechanism that has first to third elements and the third element acts as an input unit for HST output, and shifting. The output shaft, the input side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at the input side first gear ratio, and the drive source rotational power at the input side second gear ratio. The input side second clutch mechanism and the input side second that engage and disengage the power transmission of the input side first transmission mechanism and the input side second transmission mechanism, respectively, which can transmit the operation to the second element. The clutch mechanism, the first and second clutch mechanisms on the output side that engage and disengage the power transmission from the second element and the first element to the shift output shaft, the shift operation member, and the shift state of the HST are directly displayed. Alternatively, an HST sensor that indirectly detects, an output sensor that directly or indirectly detects the rotational speed of the speed change output shaft, the output adjusting member, the input side first and second clutch mechanisms, and the output side. A control device for controlling the operation of the first and second clutch mechanisms is provided, and the control device has a rotation speed of the shift output shaft less than a predetermined switching speed based on the detection signals of the HST sensor and the output sensor. In the low speed state, the first element is actuated from the drive source by engaging the input side and output side first clutch mechanisms and disengaging the input side and output side second clutch mechanisms. The HST output is generated in response to the speed-increasing operation of the speed change operating member while revealing the first transmission state in which the second element acts as the input unit of the transmitted reference power and the second element acts as the output unit of the combined rotational power. While the output adjusting member is operated so as to shift from the first HST speed to the second HST speed, when the rotation speed of the shift output shaft is higher than the switching speed, the input side and output side first clutches are used. By disengaging the mechanism and engaging the input side and the output side second clutch mechanism, the first element acts as an output unit and the second element acts as a reference power input unit. While displaying the transmission state, the output adjusting member is operated so that the HST output shifts from the second HST speed to the first HST speed in response to the speed increasing operation of the speed change operating member, and the input side first and the first The second gear ratio is the first transmission The rotational speed of the second element when the HST output is set to the second HST speed in the moving state, and the rotational power transmitted via the input-side second transmission mechanism in the second transmission state of the second element. The rotation speed is the same, and the rotation speed of the first element when the HST output is set to the second HST speed in the second transmission state and the rotation speed of the first element in the first transmission state via the input side first transmission mechanism. Provided is a transmission structure in which the rotational speed of the first element due to the transmitted rotational power is set to be the same.

In the second aspect of the present invention, preferably, when the control device is switched between the first transmission state and the second transmission state, the rotation speed appearing on the shift output shaft is switched in the transmission state after the switching. The output adjusting member is operated so as to match or approach the rotation speed appearing on the speed change output shaft in the previous transmission state.

In the various configurations of the first and second aspects of the present invention, preferably, in the switching transition period of the first and second transmission states, both the first and second clutch mechanisms on the input side are engaged. Moreover, the double transmission state in which both the first and second clutch mechanisms on the output side are engaged is displayed.

In one form in which the double transmission state appears, the input side clutch unit formed by the input side first and second clutch mechanisms and the output side clutch formed by the output side first and second clutch mechanisms. At least one of the units is a dog clutch type.

The dog clutch type clutch unit is supported by a corresponding rotating shaft so as to be relatively non-rotatable and movable in the axial direction, and has sliders having first and second concave-convex engaging portions on one side and the other side in the axial direction, respectively. Will be done.

When the slider is positioned at the first position on one side in the axial direction, the first concave-convex engaging portion corresponds to the second concave-convex engaging portion while being disengaged from the corresponding concave-convex engaging portion. By engaging with the concave-convex engaging portion, only the first clutch mechanism is engaged, and when it is positioned at the second position on the other side in the axial direction, the first concave-convex engaging portion becomes the corresponding concave-convex engaging portion. On the other hand, the first concavo-convex engaging portion is engaged with the corresponding concavo-convex engaging portion while being disengaged, so that only the second clutch mechanism is engaged, and the slider is in the axial direction. When positioned at an intermediate position between the first and second positions, both the first and second concave-convex engaging portions are engaged with the corresponding concave-convex engaging portions, so that the first and second concave-convex engaging portions are engaged. Both of the clutch mechanisms are configured to be engaged.

The input-side first transmission mechanism is operably connected to the input-side first drive gear and the input-side first drive gear, which are rotatably supported by a main drive shaft operably connected to the drive source. One element has an input-side first driven gear that cannot be relatively rotated, and the input-side second transmission mechanism includes an input-side second drive gear that is rotatably supported by the main drive shaft and the input-side second drive gear. It is assumed that the second element is actuated and connected to the second drive gear on the input side, and has a first driven gear on the input side which is not relatively rotatable.

In this case, the input side clutch unit is a dog clutch type having an input side slider as the slider.
The input side slider is supported between the input side first and second drive gears so as to be non-rotatable relative to the main drive shaft and movable in the axial direction, and when it is positioned at the first position, the second unevenness is formed. The first concave-convex engaging portion is engaged with the concave-convex engaging portion of the input-side first drive gear while the engaging portion is not engaged with the concave-convex engaging portion of the first input-side second drive gear. As a result, only the input-side first clutch mechanism is engaged, and when it is positioned at the second position, the first concave-convex engaging portion is not engaged with the concave-convex engaging portion of the input-side first drive gear. By engaging the second concavo-convex engaging portion with the concavo-convex engaging portion of the input-side second drive gear while being engaged, only the input-side second clutch mechanism is engaged and the intermediate position. When it is located at, the first and second concave-convex engaging portions are engaged with the concave-convex engaging portions of the input-side first and second drive gears, respectively, thereby engaging both the first and second clutch mechanisms. It is configured to be in a combined state.

In the transmission structure according to the first aspect, the second element is provided with a speed change intermediate shaft connected to the second element so as not to rotate relative to the axis, and the first element can be supported by the speed change intermediate shaft so as to be relatively rotatable.

In this case, the output-side first transmission mechanism is operatively connected to the output-side first drive gear supported on the shift intermediate shaft so as not to rotate relative to the shift output shaft, and is relative to the shift output shaft. It has an output-side first driven gear that is rotatably supported, and the output-side second transmission mechanism has an output-side second drive gear that is non-rotatably connected to the first element and the output-side second drive gear. It is assumed that it has an output side second driven gear that is operably connected to two drive gears and is rotatably supported relative to the speed change output shaft, and the output side first and second clutch mechanisms are the output side first. And the concave-convex engaging portion provided in the second driven gear and the first and second driven gears on the output side are supported by the speed change output shaft so as to be relatively non-rotatable and movable in the axial direction, and one side in the axial direction and It is assumed that the output side slider is provided with the first and second uneven engagement portions on the other side.

When the output side slider is positioned at the first position on one side in the axial direction, the second concave-convex engaging portion is disengaged from the concave-convex engaging portion of the output-side second driven gear. 1 The concave-convex engaging portion is engaged with the concave-convex engaging portion of the output-side first driven gear so that only the output-side first clutch mechanism is engaged and is positioned at the second position on the other side in the axial direction. Then, the first concave-convex engaging portion is disengaged from the concave-convex engaging portion of the output-side first driven gear, and the second concave-convex engaging portion engages with the concave-convex engaging portion of the output-side second driven gear. When only the output side second clutch mechanism is engaged by being engaged with the portion and is positioned at an intermediate position between the first position and the second position in the axial direction, the first and second positions are engaged. The concave-convex engaging portion is engaged with the concave-convex engaging portion of the first and second drive gears on the output side, respectively, so that both the first and second clutch mechanisms on the output side are engaged. Will be done.

In another form in which the double transmission state is exhibited, the input side clutch unit formed by the input side first and second clutch mechanisms and the output side clutch formed by the output side first and second clutch mechanisms. At least one of the units is a hydraulically actuated friction plate type that receives a pressure oil supply to bring out a clutch engaged state.

In this case, the transmission structure supplies and discharges pressure oil to a pressure oil supply line that receives pressure oil from a hydraulic source and to the first and second clutch mechanisms of the hydraulically actuated friction plate type clutch unit, respectively. The first and second supply / discharge lines and the first and second solenoid valves inserted in the first and second supply / discharge lines, respectively, the discharge position for draining the corresponding supply / discharge line and the corresponding supply / discharge line. Clutch engagement detection that detects the engagement state of the first and second solenoid valves that can take the supply position to fluidly connect the drain line to the hydraulic oil supply line and the first and second clutch mechanisms in the friction plate type clutch unit. Means and means are provided.

The control device positions the first solenoid valve at the supply position and the second solenoid valve at the discharge position when the rotation speed of the shift output shaft is lower than the switching speed, and causes the shift output shaft. When the rotation speed is higher than the switching speed, the first solenoid valve is positioned at the discharge position and the second solenoid valve is positioned at the supply position, and when switching between the low speed state and the high speed state, at the time before switching. While maintaining the solenoid valve located at the supply position at the supply position, move the solenoid valve located at the discharge position before switching from the discharge position to the supply position, and move the position from the discharge position to the supply position. After a predetermined time has elapsed from the time when it is recognized based on the signal from the clutch engagement detecting means that the clutch mechanism to which the pressure oil is supplied via the solenoid valve is in the engaged state, the supply position is before the switching. The solenoid valve located in is moved from the supply position to the discharge position.

Preferably, the first and second solenoid valves receive the hydraulic pressure of the corresponding supply / discharge line as the pilot pressure, so that the hydraulic pressure of the corresponding supply / discharge line is input in a state where the position signal from the control device to the supply position is input. Is a proportional solenoid valve configured to maintain the engaging hydraulic pressure.

In the first and second aspects of the present invention, the input-side first and second clutch mechanisms may be of a hydraulically actuated friction plate type that receives a pressure oil supply to bring out a clutch engaged state.
In this case, the transmission structure includes a pressure oil supply line that receives pressure oil from a hydraulic source, and input-side first and first and first input-side first and second clutch mechanisms that supply and discharge pressure oil to the input-side first and second clutch mechanisms, respectively. 2. Supply that is inserted into the input side first and second supply / discharge lines, respectively, and connects the discharge position for draining the corresponding supply / discharge line and the corresponding supply / discharge line to the hydraulic oil supply line. The input side first and second solenoid valves that can take a position and the clutch engagement detecting means for detecting the engaging state of the input side first and second clutch mechanisms are provided.

Preferably, the control device positions the input side first solenoid valve at the supply position and the input side second solenoid valve at the discharge position when the rotation speed of the shift output shaft is lower than the switching speed. When the rotation speed of the speed change output shaft is higher than the switching speed, the first solenoid valve on the input side is positioned at the discharge position and the second solenoid valve on the input side is positioned at the supply position. And when switching the second transmission state, the solenoid valve that was located at the supply position at the time before switching is maintained at the supply position, and the solenoid valve that was at the discharge position at the time before switching is released from the discharge position. Based on the signal from the clutch engagement detecting means, it is recognized that the clutch mechanism, which is moved to the supply position and the pressure oil is supplied via the solenoid valve moved from the discharge position to the supply position, is in a slip engagement state. At that time, the solenoid valve that was located at the supply position at the time before switching is configured to move from the supply position to the discharge position.

The transmission structure includes a pressure oil supply line that receives pressure oil from a hydraulic source, and output-side first and second supply and discharge that supply and discharge pressure oil to the output-side first and second clutch mechanisms, respectively. The line and the first and second supply / discharge lines on the output side are respectively inserted, and a discharge position for draining the corresponding supply / discharge line and a supply position for fluidly connecting the corresponding supply / discharge line to the pressure oil supply line are taken. The first and second solenoid valves on the output side to be obtained, and the clutch engagement detecting means for detecting the engagement state of the first and second clutch mechanisms on the output side may be provided.

In this case, preferably, the control device positions the output side first solenoid valve at the supply position and discharges the output side second solenoid valve in a low speed state in which the rotation speed of the shift output shaft is less than the switching speed. When the speed change output shaft is positioned at a higher speed than the switching speed, the output side first solenoid valve is positioned at the discharge position and the output side second solenoid valve is positioned at the supply position. When switching between the low speed state and the high speed state, the solenoid valve that was located at the supply position at the time before switching is maintained at the supply position, and the solenoid valve that was located at the discharge position at the time before switching is removed from the discharge position. Based on the signal from the clutch engagement detecting means, it is recognized that the clutch mechanism, which is moved to the supply position and the pressure oil is supplied via the solenoid valve moved from the discharge position to the supply position, is in a slip engagement state. At that time, the solenoid valve that was located at the supply position at the time before switching is configured to move from the supply position to the discharge position.

In the first and second aspects of the present invention, preferably, at least the input side second clutch mechanism and the output side second clutch mechanism are friction plate type clutch mechanisms.
More preferably, all of the input-side first and second clutch mechanisms and the output-side first and second clutch mechanisms are friction plate type clutch mechanisms.

The transmission structure according to the present invention is a first supply / discharger that supplies / discharges pressure oil to a pressure oil supply line whose upstream side is fluidly connected to a hydraulic source, a drain line, and the first clutch mechanism on the input side and the output side. It may include a line, a second supply / discharge line for supplying / discharging hydraulic pressure oil to the input side and output side second clutch mechanisms, and a switching valve whose position is controlled by the control device.

The switching valve connects the first position where the pressure oil supply / discharge line is fluidly connected to the first supply / discharge line and the second supply / discharge line is fluidly connected to the drain line, and the first supply / discharge line. It is configured to have a second position where the hydraulic oil supply / discharge line is fluidly connected to the drain line and the hydraulic oil supply / discharge line is fluidly connected to the second supply / discharge line, and the input side first and second clutch mechanisms and the output side are provided. The first and second clutch mechanisms are of a hydraulically actuated type that receives a pressure oil supply and engages the power transmission of the corresponding transmission mechanism.

Further, in order to achieve the above-mentioned one object, the third aspect of the present invention is a transmission structure inserted in the traveling system transmission path of the work vehicle, and the rotation is operatively input from the drive source to the pump shaft. It has an HST that outputs power from the motor shaft by steplessly shifting the power to rotational power between at least the first HST speed and the second HST speed according to the operating position of the output adjusting member, and the first to third elements. The planetary gear mechanism in which the three elements act as the input unit of the HST output, the shift output shaft, and the input side first transmission mechanism and the input side capable of transmitting the rotational power of the drive source to the first and second elements, respectively. The second transmission mechanism, the input side first clutch mechanism and the input side second clutch mechanism that engage and disengage the power transmission of the input side first transmission mechanism and the input side second transmission mechanism, respectively, the second element and the said. An output-side first and second clutch mechanism that engages and disengages power transmission from the first element to the shift output shaft, a shift operation member, and an HST sensor that directly or indirectly detects the shift state of the HST. Operation control of the output sensor that directly or indirectly detects the rotational speed of the transmission output shaft, the output adjusting member, the input side first and second clutch mechanisms, and the output side first and second clutch mechanisms. At least one of the input side clutch unit formed by the input side first and second clutch mechanisms and the output side clutch unit formed by the output side first and second clutch mechanisms is provided with a control device for controlling the above. It is a hydraulically actuated friction plate type that receives a pressure oil supply to bring out the clutch engaged state, and the transmission structure further includes a pressure oil supply line that receives the pressure oil supply from the hydraulic source and a hydraulically actuated type. The first and second supply and discharge lines for supplying and discharging pressure oil to the first and second clutch mechanisms in the friction plate type clutch unit, and the first intervening in the first and second supply and discharge lines, respectively. The first and second electromagnetic valves and the second electromagnetic valve, which can have a discharge position for draining the corresponding supply / discharge line and a supply position for fluidly connecting the corresponding supply / discharge line to the pressure oil supply line, and hydraulic pressure. The control device includes clutch engagement detecting means for detecting the engaged state of the first and second clutch mechanisms in the actuated friction plate type clutch unit, and the control device is based on the detection signals of the HST sensor and the output sensor. In a low speed state in which the rotation speed of the speed change output shaft is less than a predetermined switching speed, the input side and output side first clutch mechanisms are engaged and before. By disengaging the second clutch mechanism on the input side and the output side, the first element acts as an input portion of the reference power operatively transmitted from the drive source, and the second element is of the combined rotational power. While displaying the first transmission state that acts as an output unit, the output adjusting member is operated so that the HST output shifts from the first HST speed to the second HST speed in response to the speed increasing operation of the speed change operating member. On the other hand, when the rotation speed of the speed change output shaft is higher than the switching speed, the input side and the output side first clutch mechanism are in the cutoff state, and the input side and the output side second clutch mechanism are in the engaged state. By doing so, the HST output is performed in response to the speed-increasing operation of the speed change operating member while displaying the second transmission state in which the first element acts as an output unit and the second element acts as an input unit of the reference power. Operates the output adjusting member so as to shift from the second HST speed to the first HST speed, and further, at the time of switching between the first and second transmission states, the above-mentioned position was located at the supply position before the switching. While maintaining one of the first and second electromagnetic valves in the supply position, the other of the first and second electromagnetic valves, which was located in the discharge position at the time before switching, is moved from the discharge position to the supply position. When it is recognized based on the signal from the clutch engagement detecting means that the clutch mechanism to which the pressure oil is supplied via the other electromagnetic valve is in a slip-engaged state, the one electromagnetic valve is supplied from the supply position. Provided is a transmission structure configured to switch the engagement and disengagement of the first and second clutch mechanisms in a friction plate type clutch unit by moving to a discharge position.

Further, in order to achieve the above-mentioned one object, the fourth aspect of the present invention is to apply the rotational power operatively input from the drive source to the pump shaft from at least the first HST speed according to the operating position of the output adjusting member. HST that continuously shifts to rotational power between 2 HST speeds and outputs from the motor shaft, a planetary gear mechanism that has first to third elements and the third element acts as an input unit for HST output, and shifting. The power transmission of the input side first and second transmission mechanisms and the input side first and second transmission mechanisms capable of transmitting the rotational power of the output shaft and the drive source to the first element and the second element, respectively. The input side first and second clutch mechanisms that engage and disengage, respectively, and the forward first transmission mechanism and forward that can transmit the rotational power of the second element and the first element to the speed change output shaft in the normal rotation state, respectively. The second transmission mechanism, the reverse transmission mechanism capable of transmitting the rotational power of the second element to the shift output shaft in the reverse state, and the power of the forward first transmission mechanism, the forward second transmission mechanism, and the reverse transmission mechanism. A forward first clutch mechanism, a forward second clutch mechanism, a reverse clutch mechanism that engage and disengage transmission, a shift operation member, an HST sensor that directly or indirectly detects the shift state of the HST, and a shift output shaft. An output sensor that directly or indirectly detects the rotation speed, the output adjusting member, the input side first clutch mechanism, the input side second clutch mechanism, the forward first clutch mechanism, the forward second clutch mechanism, and the above. The control device is provided with a control device that controls the operation of the reverse clutch mechanism, and the control device increases the rotation speed of the shift output shaft from zero speed to less than the switching speed in the forward direction based on the detection signals of the HST sensor and the output sensor. In the low speed state of, the first forward transmission state in which the first clutch mechanism on the input side and the first forward clutch mechanism are engaged is displayed, and in response to the forward speed increase operation of the speed change operation member. The output adjusting member is operated so that the HST output shifts from the first HST speed to the second HST speed, and when the rotation speed of the shift output shaft is higher than the switching speed in the forward direction, the input side second The HST output changes from the first HST speed to the second HST speed in response to the forward speed increasing operation of the speed change operating member while displaying the forward second transmission state in which the clutch mechanism and the forward second clutch mechanism are engaged. In the reverse transmission state in which the output adjusting member is operated so as to shift toward, and the rotation speed of the shift output shaft changes from zero speed to the reverse side, the first clutch on the input side The HST output shifts from the first HST speed to the second HST speed in response to the reverse speed increasing operation of the speed change operating member while displaying the reverse transmission state in which the switch mechanism and the reverse clutch mechanism are engaged. Provided is a transmission structure configured to actuate the output adjusting member.

In the fourth aspect, the input-side first transmission mechanism operates and transmits the rotational power of the drive source to the first element at the input-side first gear ratio, and the input-side second transmission mechanism rotates the drive source. It is assumed that the power is transmitted to the second element at the input side second gear ratio.
In this case, preferably, the input-side first and second gear ratios are the rotational speed of the second element and the forward second transmission state when the HST output is the second HST speed in the forward first transmission state. When the rotational speed of the second element due to the rotational power transmitted via the input-side second transmission mechanism is the same and the HST output is set to the second HST speed in the forward second transmission state. The rotational speed of the first element and the rotational speed of the first element due to the rotational power transmitted via the input-side first transmission mechanism in the forward first transmission state are set to be the same.

In the fourth aspect, the forward first transmission mechanism operates and transmits the rotational power of the second element to the shift output shaft at the forward first gear ratio, and the forward second transmission mechanism is the first element male. It is assumed that the rotational power is transmitted to the shift output shaft at the forward second gear ratio.
In this case, preferably, the forward first and second gear ratios have the same rotational speeds appearing on the gear shift output shaft in the first and second transmission states when the HST output is the second HST speed. Is set to be.

In the fourth aspect, preferably, when the HST output is set to the first HST speed in the engaged state of the input side first clutch mechanism, the HST is set so that the rotation speed of the second element becomes zero speed. And the planetary gear mechanism is set.

Further, in order to achieve the above-mentioned one object, in the fifth aspect of the present invention, the rotational power operatively input from the drive source to the pump shaft is applied from at least the first HST speed according to the operating position of the output adjusting member. HST that continuously shifts to rotational power between 2 HST speeds and outputs from the motor shaft, a planetary gear mechanism that has first to third elements and the third element acts as an input unit for HST output, and shifting. The output shaft, the input side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at the input side first gear ratio, and the drive source rotational power at the input side second gear ratio. The input side second transmission mechanism capable of transmitting the operation to the second element, the input side first clutch mechanism, and the input side second that engage and disengage the power transmission of the input side first transmission mechanism and the input side second transmission mechanism, respectively. The clutch mechanism, the output side first transmission mechanism capable of transmitting the rotational power of the second element to the shift output shaft at the output side first gear ratio, and the output side second gear ratio of the rotational power of the first element. With the output side second transmission mechanism capable of transmitting the operation to the shift output shaft and the output side third gear ratio that rotates the shift output shaft at a higher speed than the output side second gear ratio for the rotational power of the first element. The output side third transmission mechanism capable of transmitting the operation to the shift output shaft, the output side first to third clutch mechanisms for engaging and disengaging the power transmission of the output side first to third transmission mechanisms, and the shift operation member. An HST sensor that directly or indirectly detects the speed change state of the HST, an output sensor that directly or indirectly detects the rotation speed of the speed change output shaft, the output adjusting member, and the input side first and second clutches. The control device includes a mechanism and a control device for controlling the operation of the first to third clutch mechanisms on the output side, and the control device is based on the detection signals of the HST sensor and the output sensor, and the rotation speed of the speed change output shaft. Is in a low speed state lower than the first switching speed, the first output side first clutch mechanism is engaged while the input side first clutch mechanism is engaged and the input side second clutch mechanism is shut off. And by setting the other output side clutch mechanism to the disengaged state, the first element acts as an input unit of the reference power operatively transmitted from the drive source, and the second element is the output of the combined rotational power. While displaying the first transmission state that acts as a unit, the output adjusting member is operated so that the HST output shifts from the first HST speed to the second HST speed in response to the speed increasing operation of the speed change operating member. In an intermediate speed state in which the rotation speed of the speed change output shaft is equal to or higher than the first switching speed and lower than the second switching speed. The input side first clutch mechanism is in the engaged state and the input side second clutch mechanism is in the engaged state, while the output side second clutch mechanism is in the engaged state and the other output side clutch mechanisms are cut off. By setting the state, the second transmission state in which the second element acts as an input unit of the reference power and the rotational power of the first element is transmitted to the shift output shaft at the output side second gear ratio appears. The output adjusting member is operated so that the HST output shifts from the second HST speed to the first HST speed in response to the speed increasing operation of the shifting operation member, and the rotation speed of the shifting output shaft is switched to the second. In a high-speed state equal to or higher than the speed, the first clutch mechanism on the input side is engaged and the second clutch mechanism on the input side is engaged, while the third clutch mechanism on the output side is engaged and another output. By setting the side clutch mechanism to the disengaged state, the second element acts as an input unit of the reference power, and the rotational power of the first element is transmitted to the shift output shaft at the output side third gear ratio. While displaying the transmission state, the output adjusting member is operated so that the HST output shifts from the side of the second HST speed to the side of the first HST speed in response to the speed increasing operation of the speed change operating member. When switching between the second and third transmission states, the rotation speed appearing on the shift output shaft in the transmission state after switching matches the rotation speed appearing on the shift output shaft in the transmission state before switching. The output adjusting member is operated so as to be close to each other, and the first and second gear ratios on the input side are the rotation speed and the second of the second element when the HST output is the second HST speed in the first transmission state. The rotational speed of the second element due to the rotational power transmitted via the second transmission mechanism on the input side in the second transmission state is the same, and the HST output is set to the second HST speed in the second transmission state. The rotation speed of the first element is set to be the same as the rotation speed of the first element due to the rotational power transmitted via the input-side first transmission mechanism in the first transmission state. Provides a transmission structure.

In the various configurations of the fifth aspect, the transmission structure is extrapolated and extrapolated to the second element so as to be relatively non-rotatable around the axis and the first. It may include a speed change transmission shaft that is non-rotatably connected to the element.

In this case, the input-side first transmission mechanism is operatively connected to the input-side first drive gear supported by the main drive shaft operably connected to the drive source and the input-side first drive gear. Further, the speed change transmission shaft has an input-side first driven gear that cannot be relatively rotated, and the input-side second transmission mechanism is an input-side second drive gear that is rotatably supported by the main drive shaft. And the input side first driven gear which is operatively connected to the input side second drive gear and which is made relative non-rotatable to the second element, and the output side first transmission mechanism is attached to the speed change intermediate shaft. It has an output-side first drive gear that is supported so that it cannot rotate relative to each other, and an output-side first driven gear that is operatively connected to the output-side first drive gear and is rotatably supported relative to the speed change output shaft. The output-side second transmission mechanism is operably connected to the output-side second drive gear that is supported so as to be non-rotatably supported by the shift transmission shaft, and is operably connected to the output-side second drive gear and is rotatable relative to the shift output shaft. The output-side third drive mechanism has a supported output-side second driven gear, and the output-side third transmission mechanism has an output-side third drive gear supported so as not to rotate relative to the speed change transmission shaft, and the output-side third drive gear. It is assumed that it has an output-side third driven gear that is operably connected to the gear and is rotatably supported relative to the speed change output shaft.

Further, the transmission structure according to the present invention further advances and reverses the rotational direction of the driving force between the transmission transmission shaft arranged on the downstream side in the transmission direction from the shift output shaft and the shift output shaft and the travel transmission shaft. It may be provided with a forward / backward switching mechanism capable of switching in a direction.

Further, in order to achieve the above-mentioned one object, the sixth aspect of the present invention is to apply the rotational power operatively input from the drive source to the pump shaft from at least the first HST speed according to the operating position of the output adjusting member. An HST that continuously shifts to rotational power between 2 HST speeds and outputs from a motor shaft, a planetary gear mechanism that has first to third elements and the third element acts as an input unit for HST output, and the above. The input side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at the input side first gear ratio and the rotational power of the drive source actuating to the second element at the input side second gear ratio. The input side second transmission mechanism that can transmit, the input side first clutch mechanism and the input side second clutch mechanism that engage and disengage the power transmission of the input side first transmission mechanism and the input side second transmission mechanism, respectively, and speed change. The output shaft, the traveling transmission shaft arranged on the downstream side in the transmission direction from the speed change output shaft, and the transmission path from the shift output shaft to the traveling transmission shaft are inserted to rotate the traveling transmission shaft in the forward direction. A forward / backward switching mechanism that can be switched between a forward transmission state and a reverse transmission state that rotates in the reverse direction, and the rotational power of the second element can be transmitted to the shift output shaft at the output side first gear ratio. The output-side first transmission mechanism, the output-side second transmission mechanism capable of transmitting the rotational power of the first element to the shift output shaft at the output-side second gear ratio, and the rotational power of the first element are transmitted. An output-side third transmission mechanism capable of transmitting operation as a driving force in the forward direction to the transmission shaft, and the rotational power of the first element via the output-side second transmission mechanism and the forward / backward switching mechanism in the forward transmission state. When the rotational power of the first element is actuated and transmitted to the traveling transmission shaft via the output side third transmission mechanism rather than the rotational speed of the traveling transmission shaft when the operation is transmitted to the traveling transmission shaft. The output side third transmission mechanism whose gear ratio is set and the power transmission of the output side first to third transmission mechanisms are engaged with each other so that the rotation speed of the traveling transmission shaft becomes high. The 1st to 3rd clutch mechanisms, the shift operation member, the HST sensor that directly or indirectly detects the shift state of the HST, the output adjusting member, the input side 1st and 2nd clutch mechanisms, and the output. Provided is a transmission structure including a control device for controlling the operation of the first to third side clutch mechanisms.

In the sixth aspect, the control device is
In response to the operation of the speed change operating member to the zero speed position, the output adjusting member is operated so that the HST output becomes the first HST speed that makes the combined rotational power zero, and the speed change operation member advances from the zero speed position. When the vehicle is operated in the forward low speed range up to the side first switching speed position, the first clutch mechanism on the input side is engaged and the second clutch mechanism on the input side is shut off while the first clutch mechanism is engaged. 1 By engaging the first output-side clutch mechanism and disengaging the other output-side clutch mechanisms, the first element acts as an input unit for reference power operatively transmitted from the drive source. Moreover, while expressing the first transmission state in which the second element acts as the output unit of the combined rotational power, the forward / reverse advance switching mechanism is brought into the forward transmission state, and in response to the speed-increasing operation of the speed change operation member. The output adjusting member is operated so that the HST output shifts from the side of the first HST speed to the side of the second HST speed.
When the speed change operating member is operated in the forward side intermediate speed range between the forward side first switching speed position and the forward side second switching speed position, the input side first clutch mechanism is shut off. By engaging the second clutch mechanism on the input side, engaging the second clutch mechanism on the output side, and disengaging the other clutch mechanism on the output side, the second element is input to the reference power. While exhibiting a second transmission state in which the rotational power of the first element is transmitted to the shift output shaft at the output side second gear ratio, the forward / backward switching mechanism is brought into the forward transmission state. In addition, the output adjusting member is operated so that the HST output shifts from the side of the second HST speed to the side of the first HST speed in response to the speed increasing operation of the speed change operating member.
When the speed change operating member is operated in the forward side high speed range exceeding the forward side second switching speed position, the input side first clutch mechanism is in the cutoff state and the input side second clutch mechanism is in the engaged state. By engaging the output-side third clutch mechanism and disengaging the other output-side clutch mechanisms, the second element acts as an input unit for reference power and the first element rotates. The HST output is generated in response to the speed-increasing operation of the speed change operating member while displaying the third transmission state in which the power is transmitted to the traveling transmission shaft as the driving force in the forward direction via the output side third transmission mechanism. The output adjusting member is operated so as to shift from the side of the second HST speed to the side of the first HST speed.
When the speed change operating member passes through the forward side second switching speed position between the forward side medium speed range and the forward side high speed range, the rotation of the traveling transmission shaft in the transmission state that appears immediately after the passage. The output adjusting member is operated so that the speed matches or approaches the rotational speed of the traveling output shaft in the transmission state that appears immediately before passing.
When the speed change operating member is operated in the reverse low speed range from the zero speed position to the reverse first switching speed position, the forward / backward switching mechanism is displayed while displaying the first transmission state. The output adjusting member is operated so as to be in the reverse transmission state and the HST output is changed from the side of the first HST speed to the side of the second HST speed in response to the speed increasing operation of the speed change operating member.
When the speed change operation member is operated in the reverse speed range exceeding the reverse reverse first switching speed position, the forward / backward switching mechanism is brought into the reverse transmission state while displaying the second transmission state. In addition, the output adjusting member is operated so that the HST output shifts from the side of the second HST speed to the side of the first HST speed in response to the speed increasing operation of the speed change operating member.

In the sixth aspect, the input-side first and second gear ratios are the same when the rotation speed of the second element and the second transmission state when the HST output is the second HST speed in the first transmission state. The rotation speed of the second element due to the rotational power transmitted via the second transmission mechanism on the input side is the same as that of the first element when the HST output is set to the second HST speed in the second transmission state. The rotation speed and the rotation speed of the first element due to the rotational power transmitted via the input-side first transmission mechanism in the first transmission state are set to be the same.

The transmission structure according to the sixth aspect may include a speed change intermediate shaft that is connected to the second element so as not to rotate relative to the axis.
In this case, the input-side first transmission mechanism is rotatably supported by the input-side first drive gear that is rotatably supported by the main drive shaft that is operatively connected to the drive source, and the transmission intermediate shaft. In this state, the input-side first drive gear and the input-side first driven gear that are operatively connected to the first element are provided, and the input-side second transmission mechanism is rotatable relative to the main drive shaft. It has a supported input-side second drive gear and an input-side second driven gear that is operatively connected to the input-side second drive gear in a state of being non-rotatably supported by the speed change intermediate shaft, and has the output. The side first transmission mechanism has an output side first driven gear that is operably connected to the input side second driven gear in a state of being supported by the speed change output shaft so as to be relatively rotatable, and the output side second transmission mechanism. Has an output-side second driven gear that is operably connected to the input-side first driven gear in a state of being relatively rotatably supported by the speed change output shaft, and the output-side third transmission mechanism is the traveling transmission. It may have an output-side third driven gear that is operatively connected to one of the output-side first and second driven gears while being supported relative to the shaft so as to be relatively rotatable.

The input-side first and second clutch mechanisms are supported by the main drive shaft so as to engage and disengage the input-side first and second drive gears with the main drive shaft, respectively, and the output-side first and second clutch mechanisms are supported. The two clutch mechanisms are supported by the shift output shaft so as to engage and disengage the output side first and second driven gears with the shift output shaft, respectively, and the output side third clutch mechanism is the output side third. The driven gear is supported by the traveling transmission shaft so as to engage and disengage the traveling transmission shaft.

Preferably, the transmission structure according to the sixth aspect further comprises a hollow housing body, a first bearing plate detachably connected to the housing body, and a longitudinal direction from the first bearing plate to the housing body. A second bearing plate detachably connected to the housing body at a separated position may be provided.

In this case, the main drive shaft, the shift intermediate shaft, the shift output shaft, and the traveling transmission shaft are supported by the first and second bearing plates in a state parallel to each other, and the input side first and second In the drive gear and the input-side first and second clutch mechanisms, the input-side first and second clutch mechanisms are positioned between the input-side first and second drive gears in the axial direction of the main drive shaft. In the state, the main drive shaft is supported by a portion of the main drive shaft located in the compartmentalized space sandwiched by the first and second bearing plates, and the input-side first and second driven gears are said to have their respective axial directions. In a state of being positioned at the same position as the first and second drive gears on the input side, it is supported by a portion of the shift intermediate shaft located in the compartment space, and the first and second driven gears on the output side and the output. In the side first and second clutch mechanisms, the output side first and second driven gears are positioned at the same positions as the input side second and first driven gears in the axial direction, respectively, and the output side first and second driven gears are located. In a state where the second clutch mechanism is located between the first and second driven gears on the input side in the axial direction, the second clutch mechanism is supported by a portion of the speed change output shaft located in the compartment space, and the third output side is supported. In the driven gear and the output side third clutch mechanism, the output side third driven gear is positioned at the same position in the axial direction as one of the output side first and second driven gears, and the output side third clutch mechanism is on the axis. In the compartmentalized space of the traveling transmission shaft in a state of being positioned on the side opposite to the output side first and second clutch mechanisms with respect to one of the output side first and second driven gears in terms of direction. Supported by a located portion, the forward / backward switching mechanism may be supported by a portion of the shift output shaft and the traveling transmission shaft located outside the compartment.

For example, the housing body may have a front housing body and a rear housing body that are detachably connected in series.
In this case, the first bearing plate is detachably connected to a boss portion provided on the inner surface of the front housing body in the vicinity of the rear opening of the front housing body, and the second bearing plate is connected to the rear housing body. Can be detachably connected to a boss portion provided on the inner surface of the rear housing body in the vicinity of the front opening of the rear housing.

In the fifth aspect and the sixth aspect, as for the output side first and second gear ratios, the rotation speeds appearing on the shift output shaft when the HST output is the second HST speed are the first and first gear ratios. 2 Can be set to be the same in the transmission state.

Instead, when the control device is switched between the first transmission state and the second transmission state, the rotation speed displayed on the shift output shaft in the transmission state after switching is the transmission state before switching. The output adjusting member may be configured to operate so as to match or approach the rotational speed appearing on the speed change output shaft.

In the various configurations of the present invention, when the rotation direction of the rotational power input to the pump shaft is the forward rotation direction, the HST uses the rotational power on one side in the forward and reverse directions as the HST output of the first HST speed. It is configured to output and output the rotational power on the other side in the forward and reverse directions as the HST output of the second HST speed.

In the various configurations, for example, the internal gear, carrier and sun gear of the planetary gear mechanism are assumed to form the first, second and third elements, respectively.

In order to achieve the other object, the present invention relates to any one of claims 1 to 7, wherein the drive source, the drive wheels, and the traveling system transmission path from the drive source to the drive wheels are interposed. Provided is a working vehicle having a transmission structure of the above, and the switching speed of the speed change output shaft is set to be higher than the working speed range.

According to the transmission structure according to the first and second aspects of the present invention, the rotation speed of the shift output shaft is increased to the switching speed as the HST output is changed from the first HST speed to the second HST speed. The first transmission state and the second transmission state in which the rotation speed of the shift output shaft is increased from the switching speed in response to the shift of the HST output from the second HST speed to the first HST speed are expressed. The shift width of the shift output shaft can be expanded, and it is possible to effectively prevent or reduce a difference in rotational speed between the shift output shafts when switching between the first and second transmission states.

Further, according to the transmission structure according to the third aspect of the present invention, the gear ratios of the first and second transmission mechanisms on the input side so that the rotation speed difference does not occur in the shift output shaft when switching between the first and second transmission states. Since it is not necessary to strictly set the gear ratios of the first and second transmission mechanisms on the output side, the degree of freedom in design is increased, and the device designability can be improved. Further, it is possible to suppress a shock when the clutch mechanism is engaged, and it is possible to suppress an unexpected power cutoff or power deceleration when the clutch mechanism is switched to be engaged under a high load traveling condition.

According to the transmission structure according to the fourth aspect of the present invention, the rotation speed of the shift output shaft is increased to the forward switching speed in response to the shift of the HST output from the first HST speed to the second HST speed. The first transmission state, the second forward transmission state in which the rotation speed of the shift output shaft is increased from the switching speed to the forward side in response to the shift of the HST output from the second HST speed to the first HST speed, and the HST. The shift width of the shift output shaft is expanded by displaying a reverse transmission state in which the rotation speed of the shift output shaft is increased to the reverse side in response to the output being shifted from the first HST speed to the second HST speed. Further, it is possible to effectively prevent or effectively prevent a difference in rotational speed between the speed change output shafts when switching between the forward first and second transmission states and the forward first transmission state and the reverse transmission state. It can be reduced.

According to the transmission structure according to the fifth aspect of the present invention, the rotation speed of the shift output shaft is increased to the first switching speed in response to the shift of the HST output from the first HST speed to the second HST speed. The transmission state, the second transmission state in which the rotation speed of the shift output shaft is increased from the first switching speed in response to the HST output being changed from the second HST speed to the first HST speed, and the HST output being the second HST. The shift width of the shift output shaft is increased by making it appear as a third transmission state in which the rotation speed of the shift output shaft is increased from the second switching speed in response to the shift from the side to the first HST side. It can be expanded, and further, it is possible to effectively prevent or reduce a difference in rotational speed between the speed change output shafts when switching between the first and second transmission states and between the second and third transmission states. can do.

According to the transmission structure according to the sixth aspect of the present invention, when the shift control member is positioned at the zero speed position, the HST output is set to the first HST speed at which the combined rotational power of the HMT becomes zero, and the shift control member When operating in the forward low speed range from the zero speed position to the forward first switching speed position, the reference power from the drive source is input to the first element of the planetary gear mechanism and from the second element. The first transmission state that outputs the combined rotational power is displayed, and the combined rotational power is transmitted to the traveling transmission shaft via the forward / backward switching mechanism that is in the forward transmission state, and the speed change operation member is increased. Correspondingly, the HST output is changed from the 1st HST speed side to the 2nd HST speed side, and the speed change operation member moves forward from the forward side 1st switching speed position to the forward side 2nd switching speed position. When operated in the range, the second transmission state in which the reference power is input to the second element and the combined rotational power is output from the first element is revealed, and the combined rotational power is referred to as the forward transmission state. While transmitting the operation to the traveling transmission shaft via the forward / backward switching mechanism, the HST output is changed from the second HST speed side to the first HST speed side according to the speed increasing operation of the speed change operating member, and the speed change operation is performed. When the member is operated in the forward side high speed range exceeding the forward side second switching speed position, the reference power is input to the second element and the combined rotational power is output from the first element, and the combined rotation is performed. While displaying the third transmission state in which power is transmitted as a driving force in the forward direction to the traveling transmission shaft via the output side third transmission mechanism, the HST output is transmitted to the second HST speed in response to the speed increasing operation of the speed change operation member. When the speed change operation member passes through the forward side second switching speed position between the forward side medium speed range and the forward side high speed range, the speed is changed immediately from the side of the first HST speed. The HST output is changed so that the rotation speed of the traveling transmission shaft in the appearing transmission state matches or approaches the rotation speed of the traveling output shaft in the transmission state that appears immediately before passing. When the speed change operating member is operated in the reverse low speed range from the zero speed position to the reverse first switching speed position, the first transmission state is displayed and the combined rotational power is transmitted backward. While transmitting to the traveling transmission shaft via the forward / backward switching mechanism in the state, the HST output is changed from the first HST speed side to the second HST speed side in response to the speed increasing operation of the speed change operation member, and the above-mentioned When the speed change operating member is operated in the reverse side high speed range exceeding the reverse side first switching speed position, the second transmission state is displayed. While transmitting the combined rotational power to the traveling transmission shaft via the forward / backward transmission switching mechanism in the reverse transmission state, the HST output is transmitted from the second HST speed side to the first HST speed in response to the speed increasing operation of the speed change operation member. Since it is configured to shift gears toward the side of, there is a difference in rotational speed between the traveling transmission shafts when switching between the first and second transmission states and between the second and third transmission states. It is possible to expand the shift width on the forward traveling side, which is frequently used, while effectively preventing or reducing the above.

FIG. 1 is a schematic transmission diagram of a work vehicle to which the transmission structure according to the first embodiment of the present invention is applied. FIG. 2 is a hydraulic circuit diagram of the transmission structure according to the first embodiment. 3A and 3B are graphs showing the relationship between the traveling vehicle speed and the HST output in the work vehicle to which the transmission structure according to the first embodiment is applied, and each of them is provided in the transmission structure. It is a graph of the low-speed stage engagement state and the high-speed stage engagement state of the auxiliary transmission mechanism. FIG. 4 is a hydraulic circuit diagram of the transmission structure according to the second embodiment of the present invention. 5 (a) and 5 (b) are graphs showing the relationship between the traveling vehicle speed and the HST output in the work vehicle to which the transmission structure according to the second embodiment is applied, and each is provided in the transmission structure. It is a graph of the low-speed stage engagement state and the high-speed stage engagement state of the auxiliary transmission mechanism. 6 (a) and 6 (b) are graphs showing the relationship between the traveling vehicle speed and the HST output in the work vehicle to which the transmission structure according to the modification of the second embodiment is applied, and each of the graphs shows the transmission structure. It is a graph of the low speed stage engagement state and the high speed stage engagement state of the auxiliary transmission mechanism provided in. FIG. 7 is a hydraulic circuit diagram of the transmission structure according to the third embodiment of the present invention. FIG. 8 is a hydraulic waveform diagram at the time of switching from the first transmission state to the second transmission state in the transmission structure according to the third embodiment. FIG. 9 is a hydraulic circuit diagram of the transmission structure according to the fourth embodiment of the present invention. FIG. 10 is a partial cross-sectional view of the vicinity of the input side clutch unit in the transmission structure according to the fourth embodiment, in which the input side first clutch mechanism is engaged by the input side slider being positioned at the first position. Moreover, it shows a state in which the second clutch mechanism on the input side is in the disconnected state. FIG. 11 is a partial cross-sectional view of the vicinity of the input-side clutch unit shown in FIG. 10, and when the input-side slider is positioned at an intermediate position, both the input-side first and second clutch mechanisms are engaged. It shows the state of being. FIG. 12 is a hydraulic waveform diagram at the time of switching from the first transmission state to the second transmission state in the transmission structure according to the fourth embodiment. FIG. 13 is a hydraulic circuit diagram of a transmission structure according to a modification of the third and fourth embodiments. FIG. 14 is a hydraulic waveform diagram at the time of switching from the first transmission state to the second transmission state in the transmission structure according to the modification. FIG. 15 is a hydraulic waveform diagram at the time of switching from the first transmission state to the second transmission state in the transmission structure according to the fifth embodiment of the present invention. FIG. 16 is a hydraulic circuit diagram of a transmission structure according to a sixth embodiment of the present invention. FIG. 17 is a hydraulic waveform diagram at the time of switching from the first transmission state to the second transmission state in the transmission structure according to the sixth embodiment of the present invention. FIG. 18 is a hydraulic waveform diagram at the time of switching from the first transmission state to the second transmission state in the transmission structure according to the modified examples of the fifth and sixth embodiments. FIG. 19 is a schematic transmission diagram of a work vehicle to which the transmission structure according to the seventh embodiment of the present invention is applied. FIG. 20 is a hydraulic circuit diagram of the transmission structure according to the seventh embodiment. 21 (a) and 21 (b) are graphs showing the relationship between the traveling vehicle speed and the HST output in the work vehicle to which the transmission structure according to the seventh embodiment is applied, and each is provided in the transmission structure. It is a graph of the low-speed stage engagement state and the high-speed stage engagement state of the auxiliary transmission mechanism. FIG. 22 is a hydraulic circuit diagram of a transmission structure according to a modified example of the seventh embodiment. FIG. 23 is a schematic transmission diagram of a work vehicle to which the transmission structure according to the eighth embodiment of the present invention is applied. FIG. 24 is a partial longitudinal side view of the work vehicle shown in FIG. 23. FIG. 25 is a graph showing the relationship between the traveling vehicle speed and the HST output in the work vehicle shown in FIG. 23. FIG. 26 is a schematic transmission diagram of a work vehicle to which the transmission structure according to the modified example of the eighth embodiment is applied. FIG. 27 is a schematic transmission diagram of a work vehicle to which the transmission structure according to the ninth embodiment of the present invention is applied. FIG. 28 is a partial longitudinal side view of the work vehicle shown in FIG. 27. FIG. 29 is a graph showing the relationship between the traveling vehicle speed and the HST output in the work vehicle shown in FIG. 27.

Embodiment 1
Hereinafter, an embodiment of the transmission structure according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a schematic transmission diagram of a work vehicle 200 to which the transmission structure 1 according to the present embodiment is applied.
Further, FIG. 2 shows a hydraulic circuit diagram of the transmission structure 1.

As shown in FIGS. 1 and 2, the work vehicle 200 has a drive source 210, drive wheels 220, and the transmission structure 1 inserted in a traveling system transmission path from the drive source 210 to the drive wheels 220. And have. Reference numeral 210a in FIGS. 1 and 2 is a flywheel included in the drive source 210.

As shown in FIGS. 1 and 2, the transmission structure 1 cooperates with the hydrostatic continuously variable transmission mechanism (HST) 10 and the HST 10 to form an HMT structure (hydrostatic / mechanical continuously variable transmission structure). The planetary gear mechanism 30 to be formed, the shift output shaft 45, the shift operation member 90 such as the shift lever whose operation position can be detected by the operation position sensor 92, and the HST sensor that directly or indirectly detects the shift state of the HST 10. It includes 95a, an output sensor 95b that directly or indirectly detects the rotation speed of the speed change output shaft 45, and a control device 100.

As shown in FIGS. 1 and 2, the HST 10 includes a pump shaft 12 operatively driven by the drive source 210, a hydraulic pump 14 supported by the pump shaft 12 so as to be relatively non-rotatable, and the hydraulic pump. A hydraulic motor 18 which is fluidly connected to a pump 14 via a pair of hydraulic oil lines 15 and is hydraulically rotationally driven by the hydraulic pump 14, a motor shaft 16 which supports the hydraulic motor 18 so as to be relatively non-rotatable, and the above. It has an output adjusting member 20 that changes the volume of at least one of the hydraulic pump 14 and the hydraulic motor 18.

The HST 10 is a ratio of the rotation speed of the HST output output from the motor shaft 16 to the rotation speed of the power input to the pump shaft 12 according to the operating position of the output adjusting member 20 (that is, the rotation speed of the HST 10). The gear ratio) can be changed steplessly.

That is, when the rotational speed of the rotational power operatively input from the drive source 210 to the pump shaft 12 is set as the reference input speed, the HST 10 has the reference input according to the operating position of the output adjusting member 20. The rotational power of the speed is steplessly changed to the rotational power between at least the first HST speed and the second HST speed, and is output from the motor shaft 16.

In the present embodiment, as shown in FIG. 1, the pump shaft 12 is connected to the main drive shaft 212 operated and connected to the drive source 210 via a gear train 214.

In the present embodiment, the HST 10 is capable of switching the rotation direction of the HST output in the forward and reverse directions.
That is, when the output adjusting member 20 is positioned at the first operating position when the rotation direction of the reference input speed is the forward rotation direction, the HST 10 has a rotation direction on one side (forward and reverse directions) from the motor shaft 16. For example, when the rotational power of the first HST speed set as the reverse direction is output and the output adjusting member 20 is positioned at the second operating position, the rotational direction from the motor shaft 16 is the opposite side in the forward and reverse directions (for example, positive). It is configured to output the rotational power of the second HST speed (in the direction of rotation).

In this case, when the output adjusting member 20 is positioned at a neutral position between the first and second operating positions, the rotation speed of the HST output becomes the neutral speed (zero speed).

In the present embodiment, as shown in FIGS. 1 and 2, the HST 10 is a movable swash plate that changes the volume of the hydraulic pump 14 by swinging around a swing axis as the output adjusting member 20. It is a plate and has a movable swash plate that can swing to one side and the other side around the swing shaft with a neutral position where the discharge amount discharged from the hydraulic pump 14 is zero.

When the movable swash plate is positioned in the neutral position, the pressure oil is not discharged from the hydraulic pump 14, and the HST 10 is in a neutral state where the output of the hydraulic motor 18 is zero.
Then, when the movable swash plate is swung from the neutral position to the normal rotation side on one side around the swing shaft, the hydraulic pump 14 supplies pressure oil to one of the pair of hydraulic oil lines 15, and the one is supplied with pressure oil. The hydraulic oil line 15 is on the high pressure side, and the other operating line 15 is on the low pressure side.
As a result, the hydraulic motor 18 is rotationally driven to the normal rotation side, and the HST 10 is in the normal rotation output state.

On the contrary, when the movable swash plate is swung from the neutral position to the reverse side on the other side around the swing shaft, the hydraulic pump 14 supplies pressure oil to the other of the pair of hydraulic oil lines 15, and the other The hydraulic oil line 15 is on the high pressure side, and one hydraulic oil line 15 is on the low pressure side.
As a result, the hydraulic motor 18 is rotationally driven to the reverse side, and the HST 10 is in the reverse output state.
In the HST 10, the volume of the hydraulic motor 18 is fixed by a fixed swash plate.

As shown in FIG. 2, the output adjusting member 20 is operated and controlled by the control device 100 based on the operation of the speed change operating member 90.
That is, the control device 100 operates the output adjusting member 20 via the actuator 110 based on the operation on the shifting operation member 90.
The actuator 110 can have various configurations such as an electric motor and a hydraulic servo mechanism as long as the operation is controlled by the control device 100.

As shown in FIGS. 1 and 2, the planetary gear mechanism 30 includes a sun gear 32, a planet gear 34 that meshes with the sun gear 32, an internal gear 36 that meshes with the planet gear 34, and the planet gear 34. It has a carrier 38 that is rotatably supported around the axis and rotates around the axis of the sun gear 32 in conjunction with the revolution of the planet gear 34 around the sun gear 32, and has the sun gear 32, the carrier 38, and the carrier 38. The internal gear 36 forms three planetary elements.

A third element, which is one of the three planetary elements, is operatively connected to the motor shaft 16, and the third element acts as a variable power input unit for inputting an HST output.
As shown in FIGS. 1 and 2, in the present embodiment, the sun gear 32 is the third element.
In the present embodiment, the sun gear 32 is operatively connected to the motor shaft 16 via a gear train 216.

In the transmission structure 1 according to the present embodiment, the first element acts as a reference power input unit for inputting the reference rotational power from the drive source 210, and the second element acts as an output unit for outputting the combined rotational power. It is possible to switch between the first transmission state to be caused and the second transmission state in which the first element acts as the output unit and the second element acts as the reference power input unit.

Specifically, as shown in FIGS. 1 and 2, the transmission structure 1 further has an input-side first transmission mechanism capable of transmitting the rotational power of the drive source 210 to the first element and the second element, respectively. The input side that engages and disengages the power transmission of the 50 (1) and the input side second transmission mechanism 50 (2) and the input side first transmission mechanism 50 (1) and the input side second transmission mechanism 50 (2), respectively. The first clutch mechanism 60 (1), the input side second clutch mechanism 60 (2), and the output side first transmission mechanism capable of transmitting the rotational power of the second element and the first element to the speed change output shaft, respectively. The output side that engages and disengages the power transmission of 70 (1) and the output side second transmission mechanism 70 (2), and the output side first transmission mechanism 70 (1) and the output side second transmission mechanism 70 (2), respectively. It has a first clutch mechanism 80 (1) and a second clutch mechanism 80 (2) on the output side.

In the present embodiment, the internal gear 36 and the carrier 38 act as first and second elements, respectively.

The input-side first transmission mechanism 50 (1) is configured to be able to transmit the rotational power of the drive source 210 to the first element (in the present embodiment, the internal gear 36) at the input-side first gear ratio. ing.

Specifically, as shown in FIGS. 1 and 2, the input-side first transmission mechanism 50 (1) and the input-side first drive gear 52 (1) connected to the main drive shaft 212 so as to be relatively rotatable. It has an input-side first driven gear 54 (1) meshed with the input-side first drive gear 52 (1) and connected to the first element.

The input-side second transmission mechanism 50 (2) is configured to be able to transmit the rotational power of the drive source 210 to the second element (the carrier 38 in the present embodiment) at the input-side second gear ratio. ..

Specifically, as shown in FIGS. 1 and 2, the input side second transmission mechanism 50 (2) and the input side second drive gear 52 (2) supported by the main drive shaft 212 so as to be relatively rotatable. It has an input side second driven gear 54 (2) meshed with the input side second drive gear 52 (2) and connected to a second element.

In the present embodiment, the first and second clutch mechanisms 60 (1) and 60 (2) on the input side are friction plate type clutch mechanisms.

Specifically, the input-side first clutch mechanism 60 (1) is supported by the input-side clutch housing 62 which is supported by the main drive shaft 212 so as to be relatively non-rotatable and the input-side clutch housing 62 which is relatively non-rotatable. The input side first including the first driven side friction plate and the first driven side friction plate supported by the input side first drive gear 52 (1) so as to be opposed to the first drive side friction plate and the first drive side friction plate. It has one friction plate group 64 (1) and an input side first piston (not shown) for frictionally engaging the input side first friction plate group 64 (1).

The input side second clutch mechanism 60 (2) is attached to the input side clutch housing 62, the second drive side friction plate supported by the input side clutch housing 62 so as not to rotate relative to the input side clutch housing 62, and the second drive side friction plate. The input side second friction plate group 64 (2) including the second driven side friction plate supported by the input side second drive gear 52 (2) so as to be opposed to each other, and the input side second friction plate group 64 (2). It has an input-side second piston (not shown) for frictionally engaging the friction plate group 64 (2).

The output-side first transmission mechanism 70 (1) is configured to be able to transmit the rotational power of the second element to the shift output shaft 45 at the output-side first gear ratio.

Specifically, the transmission structure has a speed change intermediate shaft 43 arranged coaxially with the planetary gear mechanism 30 and connected to one of the first and second elements so as not to rotate relative to the axis.

In the present embodiment, the speed change intermediate shaft 43 is connected to the second element so as not to rotate relative to each other.
On that basis, the output side first transmission mechanism 70 (1) has an output side first drive gear 72 (1) supported by the speed change intermediate shaft 43 so as not to rotate relative to the shift intermediate shaft 43, and the output side first drive gear 72. It has an output-side first driven gear 74 (1) that is meshed with (1) and is rotatably supported by the speed change output shaft 45.

The output-side second transmission mechanism 70 (2) is configured to be able to transmit the rotational power of the first element to the shift output shaft 45 at the output-side second gear ratio.

Specifically, the output side second transmission mechanism 70 (2) is meshed with the output side second drive gear 72 (2) connected to the first element and the output side second drive gear 72 (2). It has an output side second driven gear 74 (2) supported on the speed change output shaft 45 so as to be relatively rotatable.
In the present embodiment, the output side second drive gear 72 (2) is supported by the speed change intermediate shaft 43 so as to be relatively rotatable.

In the present embodiment, the output side first and second clutch mechanisms 80 (1) and 80 (2) are friction plate type clutch mechanisms.

Specifically, the output side first clutch mechanism 80 (1) rotates relative to the output side clutch housing 82 supported by the speed change output shaft 45 so as not to rotate relative to the output side first driven gear 74 (1). The output side first including the first drive-side friction plate that is impossibly supported and the first driven-side friction plate that is non-rotatably supported by the output-side clutch housing 82 while facing the first drive-side friction plate. It has one friction plate group 84 (1) and an output side first piston (not shown) for frictionally engaging the output side first friction plate group.

The output side second clutch mechanism 80 (2) includes the output side clutch housing 82, a second drive side friction plate supported by the output side second driven gear 74 (2) so as not to rotate relative to the output side clutch housing 82, and the second drive side friction plate. The output side second friction plate group 84 (2) including the second driven side friction plate supported by the output side clutch housing 82 so as to be relatively non-rotatable while facing the drive side friction plate, and the output side second friction plate group 84 (2). It has an output-side second piston (not shown) for frictionally engaging the friction plate group.

In the transmission structure 1 according to the present embodiment, the input side first and second clutch mechanisms 60 (1) and 60 (2) and the output side first and second clutch mechanisms 80 (1) and 80 (2) ) Is a hydraulically actuated type that receives a pressure oil supply and reveals an engaged state.

More specifically, as shown in FIG. 2, the transmission structure 1 further includes a pressure oil supply line 155, a drain line 157, and an input side and an output side whose upstream side is fluidly connected to a hydraulic source 150 such as a hydraulic pump. The first supply / discharge line 160 (1) for supplying / discharging hydraulic pressure to the first clutch mechanisms 60 (1) and 80 (1), and the input side and output side second clutch mechanisms 60 (2) and 80 ( It includes a second supply / discharge line 160 (2) for supplying / discharging hydraulic pressure to 2), and a switching valve 165 whose position is controlled by the control device 100.
Reference numeral 156 in FIG. 2 is a relief valve for setting the hydraulic pressure of the pressure oil supply line 155.

The switching valve 165 is a first that fluidly connects the pressure oil supply / discharge line 155 to the first supply / discharge line 160 (1) and fluidly connects the second supply / discharge line 160 (2) to the drain line 157. A position and a second position where the first supply / discharge line 160 (1) is fluidly connected to the drain line 157 and the pressure oil supply / discharge line 155 is fluidly connected to the second supply / discharge line 160 (2). It is configured to be possible.

As shown in FIG. 1, the transmission structure 1 according to the present embodiment further includes a traveling transmission shaft 235 arranged on the downstream side in the transmission direction from the shifting output shaft 45, the shifting output shaft 45, and the traveling transmission. It is provided with a forward / backward switching mechanism 230 capable of switching the rotation direction of the driving force between the shafts 235 in the forward direction and the reverse direction.

The forward / backward switching mechanism 230 is configured so that, for example, the control device 100 switches between the forward direction and the reverse direction in response to an operation of the speed change operation member 90 on the forward side and the reverse side.
That is, when the control device 100 recognizes that the speed change operating member 90 has been operated to the forward side, the forward / backward switching mechanism 230 is put into the forward transmission state, and the speed change operation member 90 is operated to the reverse side. Upon recognizing that this has been done, the forward / backward switching mechanism 230 is put into the reverse transmission state.

As shown in FIG. 1, the transmission structure 1 according to the present embodiment further includes a second traveling transmission shaft 235 arranged on the downstream side in the transmission direction from the traveling transmission shaft 235, and the traveling transmission shaft 235 and the second traveling transmission shaft 235. The auxiliary transmission mechanism 240 is provided so that the rotation speed of the driving force between the two traveling transmission shafts 245 can be changed in two stages, a high speed stage and a low speed stage.
The auxiliary transmission mechanism 240 switches between a high-speed transmission state and a low-speed transmission state, for example, in response to an artificial operation on an auxiliary transmission operation member (not shown) via a mechanical link mechanism or by the control device. Is configured to be done.

The work vehicle 200 has a pair of left and right main drive wheels as the drive wheels 220.
Therefore, as shown in FIG. 1, the work vehicle 200 further uses the pair of main drive axles 250 for driving the pair of main drive wheels and the rotational power of the second traveling transmission shaft 245 for the pair of main drive wheels. It has a differential mechanism 260 that differentially transmits to the drive axle 250.

As shown in FIG. 1, the work vehicle 200 further includes a traveling brake mechanism 255 that selectively applies a braking force to the main driving axle 250, and the pair of traveling vehicles 200 due to rotational power from the second traveling transmission shaft 245. A differential lock mechanism 265 that forcibly and synchronously drives the main drive axle 250, and a drive force extraction mechanism for the auxiliary drive wheels that can selectively output rotational power branched from the second traveling transmission shaft 245 toward the auxiliary drive wheels. It has 270 and.

Further, the work vehicle 200 has a PTO shaft 280 that outputs rotational power to the outside, and a PTO clutch mechanism 285 and a PTO multi-stage transmission mechanism 290 that are inserted in a PTO transmission path from the drive source 210 to the PTO shaft 280. Have.

Here, the HST 10 by the control device 100, the input side first and second clutch mechanisms 60 (1), 60 (2), and the output side first and second clutch mechanisms 80 (1), 80 ( The operation control of 2) will be described.

FIG. 3 shows a graph showing the relationship between the traveling vehicle speed and the rotation speed of the HST output in the work vehicle 200.
Note that FIGS. 3A and 3B are graphs in which the auxiliary transmission mechanism 240 is engaged with the low speed stage and the high speed stage, respectively.

In the state where the speed change operation member 90 is operated up to the switching speed position (that is, the rotation speed of the speed change output shaft 45 is switched to a predetermined value based on the detection signal of the output sensor 95b). In a low speed state lower than the speed), the input side and output side first clutch mechanisms 60 (1) and 80 (1) are engaged and the input side and output side second clutch mechanisms 60 (2) and 80 are engaged. By setting (2) to the cutoff state, the first element (in the present embodiment, the internal gear 36) acts as an input unit for reference power operatively transmitted from the drive source 210, and the above. The first transmission state in which the second element (the carrier 38 in the present embodiment) acts as an output unit of the combined rotational power is revealed.

The output sensor 95b detects the rotation speed of the shift output shaft 45 as long as the rotation speed of the shift output shaft 45 can be directly or indirectly recognized, and the rotation speed of the drive wheels 20 or the drive axle 250. It can take various forms such as a sensor for detecting.

The low speed state in which the rotation speed of the speed change output shaft 45 is less than a predetermined switching speed is when the auxiliary speed change mechanism 240 is engaged with the low speed stage based on the traveling vehicle speed (see FIG. 3A). Means that it is within the range of −a (L) to + a (L), and when the auxiliary transmission mechanism 240 is engaged in the high speed stage (see FIG. 3 (b)), −a ( It means that it is within the range of H) to + a (H).
The traveling vehicle speeds "+" and "-" mean that the traveling directions of the work vehicle 200 are the forward direction and the reverse direction, respectively.

In the first transmission state, the control device 100 changes the HST output from the first HST speed (in the present embodiment, the predetermined speed on the reverse side) to the first HST speed based on the HST sensor in response to the speed increasing operation of the speed change operation member 90. The output adjusting member 20 is operated so as to shift toward 2 HST speed (in the present embodiment, a predetermined speed on the normal rotation side).

The HST sensor may take various forms such as a sensor for detecting the rotational speed of the motor shaft 16 and a sensor for detecting the operating position of the output adjusting member 20 as long as the output state of the HST 10 can be detected.

That is, the control device 100 makes the first transmission state appear when the speed change operation member 90 is positioned up to the switching speed position, and then the first transmission state is displayed.
(1) When the speed change operation member 90 is positioned at the zero speed position (vehicle stop position), the first HST speed position (in the present embodiment, the reverse side is predetermined) for setting the HST output to the first HST speed. Position the output adjusting member 20 at the speed position),
(2) Until the speed change operation member 90 reaches the switching speed position (that is, until the rotation speed of the speed change output shaft 45 reaches the switching speed from zero speed (that is, the traveling vehicle speed in the work vehicle 200 of the present embodiment). As a reference, when the auxiliary transmission mechanism 240 is in the low-speed stage engaged state (FIG. 3 (a)), the speed is from zero speed to reach vehicle speed −a (L) (when moving backward), and from zero speed to vehicle speed. It corresponds to reaching + a (L) (when moving forward). Further, when the auxiliary transmission mechanism 240 is in the high-speed stage engaged state (FIG. 3 (b)), the vehicle speed is changed from zero speed to -a (H) ( It corresponds to the time when the vehicle reaches the reverse speed) and the time when the vehicle speed + a (H) (when the vehicle moves forward) is reached from the zero speed. The output adjusting member 20 is operated so as to shift from the side to the second HST speed side (in the present embodiment, the output adjusting member 20 is moved from the reverse side predetermined speed position to the forward rotation side predetermined speed position. Move to the side of),
(3) When the speed change operation member 90 is positioned at the switching speed position (that is, when the rotation speed of the speed change output shaft 45 reaches the switching speed (that is, the traveling vehicle speed in the work vehicle 200 of the present embodiment). As a reference, when the auxiliary transmission mechanism 240 is in the low-speed stage engaged state (FIG. 3 (a)), the vehicle speed −a (L) (when moving backward) is reached, and the vehicle speed + a (L) ( When the auxiliary transmission mechanism 240 reaches the high-speed stage engaged state (FIG. 3 (b)), it corresponds to the time when it reaches −a (H) (when moving backward). (Corresponding to the time when the vehicle speed + a (H) (when moving forward) is reached), at the second HST speed position (in the present embodiment, the predetermined speed position on the normal rotation side) where the HST output is set to the second HST speed. The output adjusting member 20 is positioned.

Further, when the control device 100 recognizes that the speed change operating member 90 has been operated to the high speed side beyond the switching speed position (that is, the rotation of the speed change output shaft 45 based on the detection signal of the output sensor 95b). (Recognizing that the speed has reached a high speed state equal to or higher than a predetermined switching speed), the input side and output side first clutch mechanisms 60 (1) and 80 (1) are set to the cutoff state, and the input side and output side first clutch mechanisms 60 (1) and 80 (1) are disconnected. 2 By engaging the clutch mechanisms 60 (2) and 80 (2), a second transmission state is exhibited in which the first element acts as an output unit and the second element acts as an input unit for reference power. Let me put it out.

The high-speed state in which the rotation speed of the shift output shaft 45 is equal to or higher than the predetermined switching speed is when the auxiliary transmission mechanism 240 is engaged with the low-speed stage based on the traveling vehicle speed (see FIG. 3A). Means that it is in a state of −a (L) (when moving backward) or more or + a (L) (when moving forward) or more, and when the auxiliary transmission mechanism 240 is engaged in the high speed stage (FIG. 3 (FIG. 3). b)) means that the traveling vehicle speed is -a (H) (when moving backward) or more or + a (H) (when moving forward) or more.

In the second transmission state, the control device 100 outputs the HST output from the second HST speed (in the present embodiment, the predetermined speed on the normal rotation side) based on the HST sensor in response to the speed increasing operation of the speed change operation member 90. The output adjusting member 20 is operated so as to shift toward the first HST speed (in the present embodiment, the predetermined speed on the reverse side).

That is, the control device 100 causes the second transmission state to appear when the speed change operation member 90 is operated from the switching speed position to the forward high speed side, and then the second transmission state is displayed.
(1) When the speed change operation member 90 is positioned at the switching speed position, the HST output is set to the second HST speed (in the present embodiment, the predetermined speed position on the normal rotation side). The output adjusting member 20 is positioned,
(2) When the speed change operation member 90 is positioned between the switching speed position and the maximum forward speed position (that is, until the rotation speed of the speed change output shaft 45 reaches the maximum speed from the switching speed (that is,) Based on the traveling vehicle speed of the work vehicle 200 of the present embodiment, when the auxiliary transmission mechanism 240 is in the low speed stage engaged state (FIG. 3 (a)), the vehicle speed −a (L) to the vehicle speed −b ( It corresponds to until it reaches L) (when moving backward) and until it reaches the vehicle speed + b (L) from the vehicle speed + a (L) (when moving forward), and when the auxiliary transmission mechanism 240 is in the high-speed stage engaged state. (Fig. 3 (b)) shows the vehicle speed from -a (H) to -b (H) (when moving backward) and the vehicle speed from + a (H) to + b (H) (when moving forward). )), The output adjusting member 20 is operated so that the HST output shifts from the second HST speed side to the first HST speed side in response to the speed increasing operation of the speed change operating member 90 (the present embodiment). The output adjusting member 20 is moved from the forward rotation side predetermined speed position to the reverse rotation side predetermined speed position).
(3) When the speed change operating member 90 is operated to the maximum forward speed position (that is, when the rotation speed of the speed change output shaft 45 reaches the maximum speed (that is, the traveling vehicle speed in the work vehicle 200 of the present embodiment). When the auxiliary transmission mechanism 240 is in the low-speed stage engaged state (FIG. 3 (a)), the vehicle speed −b (L) (when moving backward) is reached, and the vehicle speed + b (L). Corresponds to the time when (forward) is reached. Further, when the auxiliary transmission mechanism 240 is in the high-speed stage engaged state (FIG. 3 (b)), the time when −b (H) (reverse) is reached. , And the time when the vehicle speed + b (H) (when moving forward) is reached.)), The first HST speed position at which the HST output is set to the first HST speed (in the present embodiment, the reverse speed side predetermined speed position). The output adjusting member 20 is positioned at.

Here, in the present embodiment, the rotation speed of the second element is the second HST speed when the HST output is the second HST speed under the first transmission state in which the second element acts as an output unit. The two elements are the same as in the second transmission state in which the two elements act as the input unit of the reference power from the drive source 210 whose operation is transmitted via the input side second transmission mechanism 50 (2), and the first. When the rotation speed of one element is the second HST speed under the second transmission state in which the first element acts as an output unit, the first element is the input side first transmission mechanism 50 ( The first and second gear ratios on the input side are set so as to be the same as in the first transmission state that acts as an input unit of the reference power from the drive source that is operated and transmitted via 1). There is.

That is, in the present embodiment, the first transmission state in which the first element acts as a reference power input unit and the second element acts as an output unit, and the first element acts as an output unit and the first element. The first and second shifts on the input side so that there is no difference in rotational speed between the second element and the third element at the switching timing between the second transmission state in which the two elements act as the reference power input unit. The ratio is set.

Further, in the present embodiment, when the HST output is set to the second HST speed, the rotation speed appearing on the speed change output shaft 45 is the same in the first and second transmission states, so that the output side is the same. The first and second gear ratios are set.

That is, in the present embodiment, the output-side first and second shifts are made so that the shift output shaft 45, that is, the traveling vehicle speed does not change at the switching timing between the first and second transmission states. The ratio is set.

According to the transmission structure 1 having such a configuration, as shown in FIG. 3, the shift range (running) in which the shift output shaft 45 is accelerated by shifting the HST output from the first HST speed to the second HST speed. The shift output shaft 45 is increased by shifting the shift range of 0-a and 0 to + a based on the vehicle speed, hereinafter referred to as the low speed side shift range) and shifting the HST output from the second HST speed to the first HST speed. It is possible to continuously change the speed in the speed range (the speed range of −a to −b and + a to + b based on the traveling vehicle speed, hereinafter referred to as the high speed side shift range).

Further, when switching between the low speed side shift range (first transmission state) and the high speed side shift range (second transmission state), it is not necessary to change the operating position of the output adjusting member 20 of the HST 10. , It does not cause a change in the traveling vehicle speed.
Therefore, the switching can be smoothly executed without imposing a load on the constituent members of the traveling system transmission path in which the transmission structure 1 is inserted.

Further, the transmission structure 1 does not include a plurality of the planetary gear mechanisms 30, and causes a speed difference between the low speed side shifting range (first transmission state) and the high speed side shifting range (second transmission state). It is possible to switch without making it possible, which makes it possible to realize good transmission efficiency.

That is, if two or more planetary gear mechanisms are provided, the operating position of the output adjusting member of the HST does not need to be changed, and the traveling vehicle speed does not change. It is possible to switch the transmission state of the side shift range.
However, since the planetary gear mechanism has poor transmission efficiency, it is not possible to obtain good transmission efficiency with a configuration including two or more planetary gear mechanisms.

On the other hand, as described above, the transmission structure 1 can obtain the above-mentioned effect only by providing the single planetary gear mechanism 30.

Further, in the transmission structure 1 according to the present embodiment, as described above, the input side first and second clutch mechanisms 60 (1) and 60 (2) and the output side first and second clutch mechanisms 80 (1) and 80 (2) are friction plate type clutch mechanisms.
According to such a configuration, switching between the low speed side shift range (first transmission state) and the high speed side shift range (second transmission state) can be performed more smoothly.

Preferably, the switching speed of the shift output shaft 45, which is the switching timing between the first and second transmission states, can be set higher than the working speed range set in the work vehicle 200.

That is, work vehicles such as tractors and combines often perform heavy load work such as tilling work, plowing work suppression work, and mowing work while traveling at low speed.
Generally, in the work vehicle, the traveling vehicle speed when performing such heavy load work is set as the work speed range, and usually 0 to 8 km / h, and depending on the specifications, 0 to 10 km / h. It is set as a speed range.

Therefore, by setting the switching speed of the speed change output shaft 45 to be higher than the working speed range when the traveling vehicle speed is used as a reference, the first and second transmissions are performed in a state where heavy load work is performed. It is possible to effectively prevent switching between states.

Embodiment 2
Hereinafter, other embodiments of the transmission structure according to the present invention will be described with reference to the accompanying drawings.
FIG. 4 shows a hydraulic circuit diagram of the transmission structure 2 according to the present embodiment.
In the figure, the same members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

The transmission structure 2 according to the present embodiment is different from the transmission structure 1 according to the first embodiment in that the first and second transmission mechanisms 70 (1) and 70 (2) on the output side are deleted. To do.

In the present embodiment, the output side first and second clutch mechanisms 80 (1) and 80 (2) are the second element (the carrier 38 in the present embodiment) and the first element, respectively. (In the present embodiment, the internal gear 36) is provided so as to engage and disengage the power transmission from the speed change output shaft 45.

FIG. 5 shows a graph showing the relationship between the traveling vehicle speed and the rotation speed of the HST output in the work vehicle to which the transmission structure 2 is applied.
5 (a) and 5 (b) are graphs of the state in which the auxiliary transmission mechanism 240 is engaged with the low speed stage and the high speed stage, respectively.

As shown in FIGS. 5A and 5B, in the present embodiment, the control device 100 is
When the speed change operation member 90 is operated from the zero speed position to the first switching speed position (that is, the speed change output shaft 45 is set to a predetermined first switching speed (that is, in the first transmission state based on the detection signal of the output sensor 95b). Based on the traveling vehicle speed, -a (L) (1) (when moving backward) or + a (L) (1) (when moving forward) when engaging in the low-speed stage, and -a (H) when engaging in the high-speed stage. ) (1) (when moving backward) or + a (H) (1) (when moving forward)) is recognized, and the first transmission state is switched to the second transmission state.

Here, when the HST output is set to the second HST speed in the first transmission state, the rotation speed of the first switching speed appears on the speed change output shaft 45.

That is, the reference power from the drive source 210 is operatively input to the first element (the internal gear 36 in the present embodiment), and the third element (the sun gear 32 in the present embodiment) is the third element. When the HST output of 2 HST speed is operatively input and the combined rotational power is output from the second element (the carrier 38 in the present embodiment), the combined rotational power is operatively transmitted from the second element. The shift output shaft 45 rotates at the first switching speed.

At this time, the traveling vehicle speed is −a (L) (1) (when moving backward) or + a (L) (1) (when moving forward) when the auxiliary transmission mechanism 240 is engaged in the low speed stage (FIG. 5 (a)). ), Which is −a (H) (1) (when moving backward) or + a (H) (1) (when moving forward) (FIG. 5 (b)) when the auxiliary transmission mechanism 240 is engaged at a high speed.

When the speed change operation member 90 is operated to the first switching speed position (that is, the HST output is set to the second HST speed in the first transmission state, and the rotation speed of the speed change output shaft 45 reaches the first switching speed. When switching from the first transmission state to the second transmission state is performed), the reference power from the drive source 210 is operatively input to the second element (the carrier 38 in the present embodiment). The HST output of the second HST speed is operatively input to the third element (the sun gear 32 in the present embodiment), and the combined rotational power is output from the first element (the internal gear 38 in the present embodiment). The shift output shaft 45 is rotated by the combined rotational power operatively transmitted from the first element.

At this time, as described above, since the transmission structure 2 according to the present embodiment does not have the output side first and second transmission mechanisms 70 (1) and 70 (2), the speed change output shaft 45 The rotation speed of is changed from the first switching speed to the second switching speed.

When the rotation speed of the shift output shaft 45 is the second switching speed, the traveling vehicle speed is −a (L) (2) (when moving backward) or + a (L) when the auxiliary transmission mechanism 240 is engaged in the low speed stage. (2) (when moving forward) (FIG. 5 (a)), and when the auxiliary transmission mechanism 240 is engaged at a high speed, -a (H) (2) (when moving backward) or + a (H) (2) ( When moving forward) (Fig. 5 (b)).

That is, in the transmission structure 2 according to the present embodiment, when the first and second transmission states are switched, a rotational speed difference occurs in the speed change output shaft 45, and the traveling vehicle speed changes.

However, since the difference in rotational speed is not so large, it can be absorbed by a member forming a traveling system transmission path.
In particular, in the present embodiment, the input side first and second clutch mechanisms 60 (1) and 60 (2) and the output side first and second clutch mechanisms 80 (1) and 80 (2) are in friction. It is a plate type clutch mechanism, and the friction plate type clutch mechanism can effectively absorb the difference in rotational speed.

Instead of this, of the first and second clutch mechanisms 60 (1) and 60 (2) on the input side, the second clutch mechanism 60 (2) on the input side is engaged in the second transmission state. , And, of the output-side first and second clutch mechanisms 80 (1) and 80 (2), the output-side second clutch mechanism 80 (2) that is engaged in the second transmission state is rubbed. It is also possible to use a plate type clutch mechanism and use the remaining clutch mechanisms 60 (1) and 80 (1) as other types such as a dog clutch mechanism.

According to the transmission structure 2 having such a configuration, although a slight difference in traveling speed occurs when switching between the first and second transmission states, the first and second transmissions on the output side are compared with the first embodiment. The structure can be simplified by deleting the mechanisms 70 (1) and 70 (2).

FIG. 6 shows a graph showing the relationship between the traveling vehicle speed and the rotation speed of the HST output in the modified example of the present embodiment.
6 (a) and 6 (b) are graphs of the state in which the auxiliary transmission mechanism 240 is engaged with the low speed stage and the high speed stage, respectively.

In the modification, when switching between the first transmission state and the second transmission state, the switching speed in the transmission state after switching matches or approaches the switching speed in the transmission state before switching. As described above, the output adjusting member 20 is operated.

That is, taking the case of switching from the first transmission state to the second transmission state as an example, the control device 100 has a switching speed (second switching speed) in the second transmission state, which is the transmission state after switching. The output adjusting member 20 is configured to operate so as to match or approach the switching speed (first switching speed) in the first transmission state, which is the transmission state before switching.

According to such a modification, it is possible to effectively prevent or reduce a difference in rotational speed between the speed change output shaft 45 when switching between the first and second transmission states, that is, a difference in running speed. ..

Embodiment 3
Hereinafter, other embodiments of the transmission structure according to the present invention will be described with reference to the accompanying drawings.
FIG. 7 shows a hydraulic circuit diagram of the transmission structure 3 according to the present embodiment.
In the drawings, the same members as those in the first and second embodiments are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

In the transmission structure 3 according to the present embodiment, both the first and second clutch mechanisms 60 (1) and 60 (2) on the input side are engaged in the switching transition period of the first and second transmission states. The transmission according to the first embodiment is in that a double transmission state in which both the first and second clutch mechanisms 80 (1) and 80 (2) on the output side are engaged with each other appears. It is different from structure 1.

Specifically, the transmission structure 3 includes the input side first and second clutch mechanisms 60 (1) and 60 (2) and the output side first and second clutch mechanisms 80 (1) and 80 (2). The pressure oil supply / discharge configuration is different from that of the transmission 1 according to the first embodiment.

That is, as shown in FIG. 7, the transmission structure 3 includes the pressure oil supply line 155, the input side first clutch mechanism 60 (1), the input side second clutch mechanism 60 (2), and the output side. Input side first supply / discharge line 360 (1) and input side second supply / discharge line 360 for supplying / discharging pressure oil to the first clutch mechanism 80 (1) and the output side second clutch mechanism 80 (2), respectively. (2), the output side first supply / discharge line 362 (1), the output side second supply / discharge line 362 (2), the pressure oil supply line 155, and the input side first supply / discharge line 360 (1), input. The first electromagnetic valve on the input side inserted between the second supply / discharge line 360 (2) on the side, the first supply / discharge line 362 (1) on the output side, and the second supply / discharge line 362 (2) on the output side. 365 (1), input side second electromagnetic valve 365 (2), output side first electromagnetic valve 367 (1), output side second electromagnetic valve 367 (2), and input side first supply / discharge line 360 (1). ), The input side first supply / discharge line 360 (2), the output side first supply / discharge line 362 (1), and the output side second supply / discharge line 362 (2), respectively. (1), an input side second pressure sensor 370 (2), an output side first pressure sensor 372 (1), and an output side second pressure sensor 372 (2) are provided.

The solenoid valves 365 (1), 365 (2), 376 (1), and 367 (2) drain the corresponding supply / discharge lines 360 (1), 360 (2), 362 (1), and 362 (2). It is configured so that the discharge position to be connected and the supply position for fluidly connecting the corresponding supply / discharge lines 360 (1), 360 (2), 362 (1), and 362 (2) to the pressure oil supply line 155 can be taken. ..
In the present embodiment, the solenoid valves 365 (1), 365 (2), 367 (1), and 367 (2) are urged toward the discharge position by the urging member, and the control device 100 When the control signal from is input, it is positioned at the supply position against the urging force of the urging member.

In the present embodiment, as shown in FIG. 7, the solenoid valves 365 (1), 365 (2), 376 (1), and 367 (2) correspond to the supply / discharge lines 360 (1) and 360 ( By receiving the hydraulic pressures of 2), 362 (1), and 362 (2) as the pilot pressure, the corresponding supply / discharge lines 360 (1) and 360 (in the state where the position signal from the control device 100 to the supply position is input) It is a proportional solenoid valve configured to maintain the hydraulic pressures of 2), 362 (1), and 362 (2) at the engaging hydraulic pressure.

The position control of the solenoid valves 365 (1), 365 (2), 367 (1), and 367 (2) by the control device 100 will be described by exemplifying a case where the first transmission state can be switched to the second transmission state. ..

FIG. 8 shows a hydraulic waveform diagram of the supply / discharge lines 360 (1), 360 (2), 362 (1), and 362 (2) when switching from the first transmission state to the second transmission state.

The control device 100 is in a state where the speed change operation member 90 is located between the zero speed position and the switching speed position (that is, in a low speed state where the rotation speed of the speed change output shaft 45 is less than the switching speed). ), The input side first solenoid valve 365 (1) and the output side first solenoid valve 367 (1) are located at the supply position, and the input side second solenoid valve 365 (2) and the output side second solenoid valve The valve 367 (2) is positioned at the discharge position.

In this state, the hydraulic pressure of the input side second supply / discharge line 360 (2) and the output side second supply / discharge line 362 (2) is released, and the input side second clutch mechanism 60 (2) and the output. While the side second clutch mechanism 80 (2) is shut off, the input side first supply / discharge line 360 (1) and the output side first supply / discharge line 362 (1) are connected to the corresponding solenoid valve 365 ( 1) The input side first clutch mechanism 60 (1) and the output side first clutch mechanism 80 (1) are brought into an engaged state while being maintained at the engaging hydraulic pressure set by the pilot pressure of 367 (1). To.
As a result, the transmission structure 3 is in the first transmission state.

On the other hand, in a state in which the speed change operating member 90 is operated beyond the switching speed position (that is, in a high speed state in which the rotation speed of the speed change output shaft 45 is equal to or higher than the switching speed), the control device 100 is said. The input side first solenoid valve 365 (1) and the output side first solenoid valve 367 (1) are positioned at the discharge position, and the input side second solenoid valve 365 (2) and the output side second solenoid valve 367 ( 2) is positioned at the supply position.

In this state, the hydraulic pressure of the input side first supply / discharge line 360 (1) and the output side first supply / discharge line 362 (1) is released, and the input side first clutch mechanism 60 (1) and the output. While the side first clutch mechanism 80 (1) is shut off, the input side second supply / discharge line 360 (2) and the output side second supply / discharge line 362 (2) are the corresponding solenoid valves 365. (2) The input side second clutch mechanism 60 (2) and the output side second clutch mechanism 80 (2) are in an engaged state while being maintained at the engaging hydraulic pressure set by the pilot pressure of 367 (2). Will be done.
As a result, the transmission structure 3 is in the second transmission state.

Here, when it is recognized that the speed change operation member 90 has been operated to the switching speed position at time Ta (see FIG. 8) (that is, the rotation speed of the speed change output shaft 45 is switched based on the signal from the output sensor 95b). (Recognizing that the switching speed has been reached from a state of less than speed), the control device 100 is the input that was located at the supply position at the time before switching the transmission state (in this example, the time of the first transmission state). The input side second solenoid valve 365, which was located at the discharge position before switching while maintaining the side first solenoid valve 365 (1) and the output side first solenoid valve 367 (1) at the supply position. (2) and the output side second solenoid valve 367 (2) are moved from the discharge position to the supply position.

As a result, the input-side first supply / discharge line 360 (1) and the output-side first supply / discharge line 362 (1) are maintained at the engaging hydraulic pressure, and the input-side second supply / discharge line 360 at time Tb. (2) and the output side second supply / discharge line 362 (2) rise to the engaging hydraulic pressure, and the double transmission state appears.

After that, the control device 100 is supplied with hydraulic pressure via the input side second solenoid valve 365 (2) and the output side second solenoid valve 367 (2) whose position has been moved to the supply position. 2 Based on the signals from the pressure sensors 370 (2) and 372 (2) corresponding to the hydraulic pressure of the supply / discharge line 360 (2) and the output side second supply / discharge line 362 (2) reaching the engaging hydraulic pressure. At the time when a predetermined time elapses (time Tc) from the recognized time (time Tb), the input side first solenoid valve 365 (1) and the output side first solenoid valve located at the supply position at the time before switching. Move 367 (1) from the supply position to the discharge position.

As a result, the input side second clutch mechanism 60 (2) and the output side second clutch mechanism 80 (2) are engaged with each other, while the input side first clutch mechanism 60 (1) and the output side second clutch mechanism 60 (1) are engaged. The second transmission state in which the 1-clutch mechanism 80 (1) is cut off appears.

According to the transmission structure 3 according to the present embodiment having such a configuration, it is possible to effectively prevent a state in which the traveling driving force is not transmitted to the drive wheels 220 when switching between the first and second transmission states. Can be done.
This is particularly effective when switching between the first and second transmission states occurs during work travel.

In the present embodiment, the pressure sensors 370 (1), 370 (2), 372 (1), and 372 (2) are configured to detect the engaged state of the corresponding friction plate type clutch mechanism. However, instead of this, another clutch engagement detection that detects the supply current value, supply current time, etc. to the proportional solenoid valves 365 (1), 365 (2), 376 (1), and 367 (2). It can also be configured to detect the engaged state of the corresponding friction plate type clutch mechanism by means.

Embodiment 4
Hereinafter, other embodiments of the transmission structure according to the present invention will be described with reference to the accompanying drawings.
FIG. 9 shows a hydraulic circuit diagram of the transmission structure 4 according to the present embodiment.
In the figure, the same members as those in the first to third embodiments are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

The transmission structure 4 according to the present embodiment is a friction plate type input side first and second clutch mechanisms 60 (1), 60 (2) and the above, as compared with the transmission structure 1 according to the first embodiment. Instead of the output-side first and second clutch mechanisms 80 (1) and 80 (2), it has a dog clutch type input-side clutch unit 410 and an output-side clutch unit 430.

FIG. 10 shows a partial cross-sectional view of the input side clutch unit 410.
As shown in FIG. 10, the input side clutch unit 410 has an input side slider 412 supported by a corresponding main drive shaft 212 so as to be relatively non-rotatable and movable in the axial direction.

The input-side slider 412 is arranged between the input-side first and second drive gears 52 (1) and 52 (2), and is located in one of the axial directions close to the input-side first drive gear 52 (19). It has a first concavo-convex engaging portion 412 (1) on the side and a second concavo-convex engaging portion 412 (2) on the other side in the axial direction close to the input side second drive gear 52 (2). ing.

The input-side clutch unit 410 further has uneven engagement portions 414 (1) and 414 (2) formed on the input-side first and second drive gears 52 (1) and 52 (2), respectively. ing.

That is, when the input side slider 412 is positioned at the first position on one side in the axial direction shown in FIG. 10, the second uneven engagement portion 412 (2) of the input side second drive gear 52 (2) The first concave-convex engaging portion 412 (1) is engaged with the concave-convex engaging portion 414 (1) of the input side first drive gear 52 (1) while being disengaged from the concave-convex engaging portion 414 (2). By being engaged, the input side first drive gear 52 (1) is connected to the main drive shaft 212, and the input formed by the first uneven portion 412 (1) and the uneven portion 414 (1). Only the first side clutch mechanism is engaged.

Further, when the input side slider 412 is positioned at the second position on the other side in the axial direction, the first concave-convex engaging portion 412 (1) engages with the concave-convex portion of the input-side first drive gear 52 (1). The second concave-convex engaging portion 412 (2) is engaged with the concave-convex engaging portion 414 (2) of the input-side second drive gear 52 (2) while being disengaged from the portion 414 (1). As a result, the input side second drive gear 52 (2) is connected to the main drive shaft 212, and the input side second formed by the second uneven portion 412 (2) and the uneven portion 414 (2). Only the clutch mechanism is engaged.

Further, as shown in FIG. 11, when the input side slider 412 is positioned at an intermediate position between the first and second positions in the axial direction, the first and second uneven engagement portions 412 (1), The 412 (2) is engaged with the concave-convex engaging portions 414 (1) and 414 (2) of the input-side first and second drive gears 52 (1) and 52 (2), respectively, so that the input-side first and second drive gears 52 (1) and 52 (2) are engaged with each other. Both the 1st and 2nd drive gears 52 (1) and 52 (2) are connected to the main drive shaft 212, and both the input side 1st and 2nd clutch mechanisms are engaged.

That is, when the input side slider 412 moves between the first position where the first transmission state is displayed and the second position where the second transmission state is displayed, the input side first and the input side slider 412 are always used. It passes through an intermediate position that engages both of the second clutch mechanisms.

Also in the transmission structure 4 according to the present embodiment having such a configuration, it is possible to effectively prevent a state in which the traveling driving force is not transmitted to the drive wheels when switching between the first and second transmission states. ..

The output side clutch unit 430 has substantially the same configuration as the input side clutch unit 410.

That is, the output-side clutch unit 430 has a concavo-convex engaging portion (not shown) formed on the output-side first and second driven gears 74 (1) and 74 (2), respectively, and the output in the axial direction. Between the first and second driven gears 74 (1) and 74 (2), the corresponding speed change output shaft 45 has an output side slider 432 supported so as to be relatively non-rotatable and movable in the axial direction.

The output side slider 432 has a first uneven engagement portion (not shown) on one side in the axial direction close to the output side first driven gear 74 (1), and the output side second driven gear. A second uneven engagement portion (not shown) is provided on the other side in the axial direction close to 74 (2).

When the output side slider 432 is positioned at the first position on one side in the axial direction, the second concave-convex engaging portion is not engaged with the concave-convex engaging portion of the output-side second driven gear 74 (2). By engaging the first concave-convex engaging portion with the concave-convex engaging portion of the output-side first driven gear, the output-side first driven gear 74 (1) is connected to the speed change output shaft 45. Therefore, only the output-side first clutch mechanism formed by the first concavo-convex engaging portion and the concavo-convex engaging portion of the output-side first driven gear 74 (1) is engaged.

Further, when the output side slider 432 is positioned at the second position on the other side in the axial direction, the first concave-convex engaging portion engages with the concave-convex engaging portion of the output-side first driven gear 74 (1). The output side second driven gear 74 (2) is engaged by engaging the second concave-convex engaging portion with the concave-convex engaging portion of the output side second driven gear 74 (2) while being disengaged. Only the output-side second clutch mechanism formed by the second concavo-convex engaging portion and the concavo-convex portion of the output-side second driven gear 74 (2) is engaged with the speed change output shaft 45.

Further, when the input side slider 432 is positioned at an intermediate position between the first and second positions in the axial direction, the first and second uneven engagement portions are engaged with the output side first and second driven gears 74. By engaging with the uneven engaging portions of (1) and 74 (2), respectively, both the first and second driven gears 74 (1) and 74 (2) on the output side are connected to the speed change output shaft 45. Then, both the first and second clutch mechanisms on the output side are engaged.

The transmission structure 4 according to the present embodiment has a hydraulic drive mechanism as a pushing mechanism for the input side slider 412 and the output side slider 432.

The hydraulic drive mechanism pushes the input side slider 412 toward the first position by the pressure oil supply line 155, the drain line 157, and the supplied pressure oil, and the input side first oil chamber 450 (1). ), The input side second oil chamber 450 (2) that pushes the input side slider 412 toward the second position by the supplied pressure oil, and the output side slider 432 is the first by the supplied pressure oil. An output side first oil chamber 452 (1) that pushes toward a position, and an output side second oil chamber 452 (2) that pushes the output side slider 432 toward a second position by the supplied pressure oil. A first supply / discharge line 460 (1) for supplying / discharging pressure oil to the input side first oil chamber 450 (1) and the output side first oil chamber 452 (1), and the input side second oil chamber 460 (1). A second supply / discharge line 460 (2) for supplying / discharging pressure oil to the oil chamber 450 (2) and the output side second oil chamber 452 (2), and an electromagnetic valve 465 whose position is controlled by the control device 100. And have.

In the figure, reference numeral 414 is an urging member for urging the input side slider 412 toward one side in the axial direction (first position value in the illustrated example), and reference numeral 434 is the output side slider. It is an urging member that urges 432 toward one side in the axial direction (first position in the illustrated example).

In the solenoid valve 465, the first supply / discharge line 155 is fluidly connected to the first supply / discharge line 460 (1) and the second supply / discharge line 460 (2) is fluidly connected to the drain line 157. The position and the second position where the first supply / discharge line 460 (1) is fluidly connected to the drain line 157 and the pressure oil supply / discharge line 155 is fluidly connected to the second supply / discharge line 460 (2). It is configured to be possible.

FIG. 12 shows a hydraulic waveform diagram of the first and second supply / discharge lines 460 (1) and 460 (2) at the time of switching from the first transmission state to the second transmission state.

The control device 100 is in a state where the speed change operation member 90 is located between the zero speed position and the switching speed position (that is, in a low speed state where the rotation speed of the speed change output shaft 45 is less than the switching speed). ), The solenoid valve 465 is positioned at the first position.

In this state, the hydraulic pressure of the second supply / discharge line 460 (2) is released, pressure oil is supplied to the first supply / discharge line 460 (1), and the input side slider 412 and the output side slider 432 It is located in the first position.

As a result, the input side second clutch mechanism and the output side second clutch mechanism are brought into an engaged state, while the input side first clutch mechanism and the output side first clutch mechanism are put into an engaged state, and the transmission is brought into an engaged state. The structure 4 is in the first transmission state.

In the control device 100, when the speed change operation member 90 exceeds the switching speed position (when the rotation speed of the speed change output shaft 45 is higher than the switching speed), the solenoid valve 465 is moved to the second position. To position.

In this state, the hydraulic pressure of the first supply / discharge line 460 (1) is released, pressure oil is supplied to the second supply / discharge line 460 (2), and the input side slider 412 and the output side slider 432 It is located in the second position.

As a result, the input side first clutch mechanism and the output side first clutch mechanism are brought into the disengaged state, while the input side second clutch mechanism and the output side second clutch mechanism are put into the engaged state, and the transmission is brought into the engaged state. The structure is in the second transmission state.

Here, when it is recognized that the speed change operating member 90 has been operated from the zero speed position side to the switching speed position at time Ta (see FIG. 12) (that is, the speed change output is based on the signal from the output sensor 95b). (Recognizing that the rotation speed of the shaft 45 has reached the switching speed from a state of being less than the switching speed), the control device 100 moves the solenoid valve 465 from the first position to the second position.

As a result, the input side slider 412 and the output side slider 432 are moved from the first position located at the time Ta, to the second position, and reach the second position at the time Tb. Then, a double transmission state appears at an intermediate position during this movement.

In the third embodiment, both the input side clutch unit and the output side clutch unit are of the friction plate type, and in the fourth embodiment, both the input side clutch unit and the output side clutch unit are of the dog clutch type. However, the present invention is not limited to such a configuration.

That is, it is also possible to make one of the input side clutch unit and the output side clutch unit a friction plate type and the other a dog clutch type.

FIG. 13 shows a hydraulic circuit diagram of the transmission structure 5 according to a modified example in which the input side clutch unit is a dog clutch type and the output side clutch unit is a friction plate type.
Further, FIG. 14 shows a hydraulic waveform diagram of the transmission structure 5 at the time of switching from the first transmission state to the second transmission state.

Further, as a matter of course, it is also possible to apply the configuration relating to the double transmission structure in the third and fourth embodiments to the second embodiment.

Embodiment 5
Hereinafter, other embodiments of the transmission structure according to the present invention will be described with reference to the accompanying drawings.

In the transmission structure according to the present embodiment, the positions of the solenoid valves 365 (1), 365 (2), 376 (1), and 376 (2) by the control device 100 when the first and second transmission states are switched. It differs from the transmission structure 3 according to the third embodiment only in that the control timing is changed.

FIG. 15 shows a hydraulic waveform diagram of the supply / discharge lines 360 (1), 360 (2), 362 (1), and 362 (2) when switching from the first transmission state to the second transmission state.

In the state where the speed change operation member 90 is positioned up to the switching speed position (that is, in the low speed state where the rotation speed of the speed change output shaft 45 is less than the switching speed), the control device 100 is subjected to the electromagnetic wave. The same position control as in the third embodiment is performed on the valves 365 (1), 365 (2), 376 (1), and 367 (2).

That is, the control device 100 positions the input side first solenoid valve 365 (1) and the output side first solenoid valve 367 (1) at the supply position, and the input side second solenoid valve 365 (2) and the control device 100. The output side second solenoid valve 367 (2) is positioned at the discharge position.

In this state, as shown in FIG. 15, the hydraulic pressures of the input side second supply / discharge line 360 (2) and the output side second supply / discharge line 362 (2) are released, and the input side second clutch mechanism. While the 60 (2) and the output side second clutch mechanism 80 (2) are shut off, the input side first supply / discharge line 360 (1) and the output side first supply / discharge line 362 (1) are The input side first clutch mechanism 60 (1) and the output side first clutch mechanism 80 (1) are maintained at the engaging hydraulic pressure set by the pilot pressures of the corresponding solenoid valves 365 (1) and 367 (1). ) Is in the engaged state.
As a result, the transmission structure is put into the first transmission state.

Further, even when the speed change operation member 90 exceeds the switching speed position (that is, even when the rotation speed of the speed change output shaft 45 is higher than the switching speed), the control device 100 uses the solenoid valve 365 (that is, the solenoid valve 365). The same position control as in the third embodiment is performed on 1), 365 (2), 367 (1), and 367 (2).

That is, the control device 100 positions the input side first solenoid valve 365 (1) and the output side first solenoid valve 367 (1) at the discharge position, and the input side second solenoid valve 365 (2) and the control device 100. The output side second solenoid valve 367 (2) is positioned at the supply position.

In this state, as shown in FIG. 15, the hydraulic pressures of the input side first supply / discharge line 360 (1) and the output side first supply / discharge line 362 (1) are released, and the input side first clutch mechanism. While the 60 (1) and the output side first clutch mechanism 80 (1) are shut off, the input side second supply / discharge line 360 (2) and the output side second supply / discharge line 362 (2) are , The input side second clutch mechanism 60 (2) and the output side second clutch mechanism 80 (maintained at the engaging hydraulic pressure set by the pilot pressure of the corresponding solenoid valves 365 (2) and 367 (2). 2) is in the engaged state.
As a result, the transmission structure 3 is in the second transmission state.

On the other hand, at the time of switching between the first and second transmission states, the control device 100 performs the above-mentioned implementation with respect to the solenoid valves 365 (1), 365 (2), 376 (1) and 376 (2). Position control different from that in the third embodiment is performed.

That is, when it is recognized that the speed change operation member 90 has been operated from the zero speed position side to the switching speed position at the time Ta in FIG. 15 (that is, the speed change output shaft 45 is based on the signal from the output sensor 95b. (Recognizing that the switching speed has been reached from a state where the rotation speed is less than the switching speed), the control device 100 is positioned at the supply position at a time before the transmission state switching (in this example, the time of the first transmission state). While maintaining the input-side first solenoid valve 365 (1) and the output-side first solenoid valve 367 (1) at the supply position, the input-side first solenoid valve 367 (1) was located at the discharge position before switching. 2 The solenoid valve 365 (2) and the output-side second solenoid valve 367 (2) are moved from the discharge position to the supply position.

As a result, the input side first supply / discharge line 360 (1) and the output side first supply / discharge line 362 (1) are maintained at the engaging hydraulic pressure, and the input side second supply / discharge line 360 (2). And the hydraulic pressure of the output side second supply / discharge line 362 (2) gradually rises and reaches the engaging hydraulic pressure at time Tb.

Here, the control device 100 was supplied with hydraulic pressure via the input side second solenoid valve 365 (2) and the output side second solenoid valve 367 (2) whose positions were moved from the discharge position to the supply position. The pressure sensor 370 (2) corresponding to the fact that the hydraulic pressure of the input side second supply / discharge line 360 (2) and the output side second supply / discharge line 362 (2) reaches the switching hydraulic pressure P lower than the engagement hydraulic pressure, When recognized based on the signal from 372 (2), the input side first solenoid valve 365 (1) and the output side first solenoid valve 367 (1), which were located at the supply position at the time before switching, are supplied. Move from to the discharge position.
The switching hydraulic pressure P is a hydraulic pressure in which the friction plate group of the corresponding clutch mechanism is in a sliding engagement state in which power is transmitted while sliding.

According to the transmission structure according to the present embodiment having such a configuration, it is possible to prevent a state in which the traveling driving force is not transmitted to the drive wheels 220 when switching between the first and second transmission states. Can be effectively prevented or reduced, and the switching shock that may occur when switching between the first and second transmission states can be effectively prevented or reduced.

That is, the input-side first and second gear ratios are the rotation speed of the second element when the HST output is set to the second HST speed in the first transmission state and the input-side second gear ratio in the second transmission state. The rotation speed of the second element due to the rotational power transmitted via the transmission mechanism 50 (2) is the same as that of the first element when the HST output is set to the second HST speed in the second transmission state. The rotation speed and the rotation speed of the first element due to the rotational power transmitted via the input-side first transmission mechanism 50 (1) in the first transmission state are set to be the same.

Therefore, in theory, there is no difference in rotational speed between the first element and / or the second element when the first and second transmission states are switched.
However, due to a manufacturing error or the like, a difference in rotational speed may occur between the first element and / or the second element when switching between the first and second transmission states.

Regarding this point, in the present embodiment, even if there is a difference in rotational speed between the first element and / or the second element when switching between the first and second transmission states, the first and second transmission states A clutch mechanism (in the example of FIG. 15) in which hydraulic pressure is supplied via an electromagnetic valve (in the example of FIG. 15, the input side second electromagnetic valve 365 (2)) whose position is moved from the cutoff position to the supply position at the time of switching. Is that the friction plate group of the input side second clutch mechanism 60 (2) is gradually frictionally engaged while sliding, the hydraulic pressure of the clutch mechanism reaches the engaging hydraulic pressure, and the clutch mechanism is in a completely engaged state. Immediately before this, the clutch mechanism (in the example of FIG. 15, the input-side first clutch mechanism 60 (1)) that was in the engaged state before switching between the first and second transmission states is released from the engaging hydraulic pressure. Will be done.

Therefore, while preventing or reducing as much as possible a state in which the traveling driving force is not transmitted to the drive wheels 220 when switching between the first and second transmission states, the switching between the first and second transmission states is further performed. It is possible to effectively prevent or reduce damage to the transmission system due to a switching shock or a double transmission state that may occur at times.

Further, the first and second gear ratios on the output side are such that the rotational speeds appearing on the shift output shaft 45 when the HST output is the second HST speed are the same in the first and second transmission states. Is set to.

Therefore, in theory, there is no difference in rotational speed between the speed change output shaft 45 when switching between the first and second transmission states.
However, due to a manufacturing error or the like, a difference in rotational speed may occur in the speed change output shaft 45 when switching between the first and second transmission states.

Regarding this point, in the present embodiment, even if a difference in rotational speed occurs in the speed change output shaft 45 when switching between the first and second transmission states, the clutch position is used when switching between the first and second transmission states. A clutch mechanism (in the example of FIG. 15, the output side second) in which hydraulic pressure is supplied via an electromagnetic valve (in the example of FIG. 15, the output side second electromagnetic valve 367 (2)) moved to the supply position. Immediately before the friction plate group of the clutch mechanism 80 (2) is gradually frictionally engaged while sliding, and the hydraulic pressure of the clutch mechanism reaches the engaging hydraulic pressure and the clutch mechanism is in a fully engaged state, the first and the first The hydraulic pressure of the clutch mechanism (in the example of FIG. 15, the output side first clutch mechanism 80 (1)) that was in the engaged state before the switching of the second transmission state is released from the engaging hydraulic pressure.

Therefore, while preventing or reducing as much as possible a state in which the traveling driving force is not transmitted to the drive wheels 220 when switching between the first and second transmission states, the switching between the first and second transmission states is further performed. It is possible to effectively prevent or reduce damage to the transmission system due to a switching shock or a double transmission state that may occur at times.

At the time of switching between the first and second transmission states, the solenoid valve that was located at the supply position at the time before switching (in the example of FIG. 15, the input side first solenoid valve 365 (1) and the output side first solenoid valve). 1 Solenoid valve 367 (1)) was maintained at the supply position, and the solenoid valve was located at the discharge position before switching (in the example of FIG. 15, the input side second solenoid valve 365 (2) and The output side second solenoid valve 367 (2) is moved from the discharge position to the supply position, and the pressure oil is supplied via the solenoid valve moved from the discharge position to the supply position (example of FIG. 15). Immediately before the hydraulic pressures of the input side second supply / discharge line 360 (2) and the output side second supply / discharge solenoid 362 (2) reach the engaging hydraulic pressure and the clutch mechanism is in a fully engaged state. , The solenoid valve that was located at the supply position at the time before switching (in the example of FIG. 15, the input side first solenoid valve 365 (1) and the output side first solenoid valve 367 (1)) is moved from the supply position. The configuration for moving to the discharge position is the input side formed by the input side first and second clutch mechanisms 60 (1) and 60 (2), which may cause a difference in rotation speed due to a manufacturing error or the like. It is applied only to one of the clutch unit and the output side clutch unit formed by the output side first and second clutch mechanisms 80 (1) and 80 (2), and when there is no or little possibility of the other. It is also possible to adopt the dog clutch type shown in FIG. 10 described above to reduce the cost.

Embodiment 6
Hereinafter, other embodiments of the transmission structure according to the present invention will be described with reference to the accompanying drawings.
FIG. 16 shows a hydraulic circuit diagram of the transmission structure 6 according to the present embodiment.
In the figure, the same members as in the embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

In the transmission structure 1 according to the first embodiment, the input-side first gear ratio of the input-side first transmission mechanism 50 (1) and the second gear ratio of the input-side second transmission mechanism 50 (2) are different. The rotational speed of the second element when the HST output is set to the second HST speed in the first transmission state, and the rotational power transmitted via the input-side second transmission mechanism 50 (2) in the second transmission state. The rotation speed of the second element is the same as that of the second element, and the rotation speed of the first element when the HST output is set to the second HST speed in the second transmission state and the input side first in the first transmission state. 1 The rotation speed of the first element due to the rotational power transmitted via the transmission mechanism 50 (1) is set to be the same, and further, the output of the output side first transmission mechanism 70 (1) is set. As for the first gear ratio on the side and the second gear ratio of the second transmission mechanism 70 (2) on the output side, the rotation speed appearing on the shift output shaft 45 when the HST output is the second HST speed is the first. And it is set to be the same in the second transmission state.

According to the transmission structure 1 according to the first embodiment, theoretically, when the first and second transmission states are switched, the rotation speed of the first element and / or the second element and the speed change output shaft 45 There is no difference.

However, the first and second gear ratios on the input side are set to the ideal set values in relation to the number of teeth of the gears constituting the first and second transmission mechanisms 50 (1) and 50 (2) on the input side. It may not be possible to set to.
In such a case, at the time of switching between the first and second transmission states, a rotation speed difference occurs in the first element and / or a rotation speed difference occurs in the second element.

Similarly, the output side first and second transmission ratios are set to the ideal setting in relation to the number of teeth of the gears constituting the output side first and second transmission mechanisms 70 (1) and 70 (2). It may not be possible to set the value.
In such a case, a difference in rotational speed will occur in the speed change output shaft 45 when switching between the first and second transmission states.

In view of this point, the transmission structure 6 according to the present embodiment has a rotational speed difference between the first element and / or the second element and the speed change output shaft 45 when the first and second transmission states are switched. Is configured so that damage to the transmission system due to a switching shock or a double transmission state due to this difference in rotational speed can be prevented or reduced as much as possible.

Specifically, as shown in FIG. 16, the transmission structure 6 according to the present embodiment has the input side first and second transmission mechanisms 50 (compared to the transmission structure 1 according to the first embodiment). It has input-side first and second transmission mechanisms 650 (1) and 650 (2) in place of 1) and 50 (2), and also has output-side first and second transmission mechanisms 70 (1) and 70. Instead of (2), it has first and second transmission mechanisms 670 (1) and 670 (2) on the output side.

As shown in FIG. 16, the input-side first transmission mechanism 650 (1) has an input-side first drive gear 652 (1) connected to the main drive shaft 212 so as to be relatively rotatable, and the input-side first drive gear 652 (1). It has an input-side first driven gear 654 (1) that is meshed with the drive gear 652 (1) and connected to the first element.

The input-side second transmission mechanism 650 (2) is attached to the input-side second drive gear 652 (2) and the input-side second drive gear 652 (2), which are rotatably supported by the main drive shaft 212. It has an input-side second driven gear 654 (2) that is meshed and connected to the second element.

The output-side first transmission mechanism 670 (1) is attached to the output-side first drive gear 672 (1) and the output-side first drive gear 672 (1), which are non-rotatably supported by the transmission intermediate shaft 43. It has an output-side first driven gear 674 (1) that is meshed and supported by the speed change output shaft 45 so as to be relatively rotatable.

The output side second transmission mechanism 670 (2) is meshed with the output side second drive gear 672 (2) connected to the first element and the output side second drive gear 672 (2), and the speed change. It has an output side second driven gear 674 (2) supported on the output shaft 45 so as to be relatively rotatable.

FIG. 17 shows a hydraulic waveform diagram of the supply / discharge lines 360 (1), 360 (2), 362 (1), and 362 (2) when switching from the first transmission state to the second transmission state.

In the present embodiment, when the first and second transmission states are switched, the control device 100 relates to the solenoid valves 365 (1), 365 (2), 376 (1), and 376 (2). , The same position control as in the fifth embodiment is performed.

That is, when it is recognized that the rotation speed of the speed change output shaft 45 has reached the switching speed from a state of being less than the switching speed based on the signal from the output sensor 95b at the time Ta in FIG. 17, the control device 100 is in the transmission state. The input side first solenoid valve 365 (1) and the output side first solenoid valve 367 (1), which were located at the supply position at the time before switching (in this example, the time of the first transmission state), are supplied. The input side second solenoid valve 365 (2) and the output side second solenoid valve 367 (2), which were located at the discharge position at the time before switching, are moved from the discharge position to the supply position. ..

As a result, as shown in FIG. 17, the input side first supply / discharge line 360 (1) and the output side first supply / discharge line 362 (1) are maintained at the engaging hydraulic pressure, and the input side second supply / discharge line 362 (1) is maintained. The hydraulic pressures of the supply / discharge line 360 (2) and the output side second supply / discharge line 362 (2) gradually increase and reach the engagement hydraulic pressure at time Tb.

Here, the control device 100 was supplied with hydraulic pressure via the input side second solenoid valve 365 (2) and the output side second solenoid valve 367 (2) whose positions were moved from the discharge position to the supply position. The pressure sensor 370 (2) corresponding to the fact that the hydraulic pressure of the input side second supply / discharge line 360 (2) and the output side second supply / discharge line 362 (2) reaches the switching hydraulic pressure P lower than the engagement hydraulic pressure, When recognized based on the signal from 372 (2), the input side first solenoid valve 365 (1) and the output side first solenoid valve 367 (1), which were located at the supply position at the time before switching, are supplied. Move from to the discharge position.

According to the transmission structure 6 having such a configuration, it is assumed that a difference in rotational speed occurs between the first element and / or the second element and the shift output shaft 45 when switching between the first and second transmission states. Also, an electromagnetic valve whose position has been moved from the cutoff position to the supply position when switching between the first and second transmission states (in the example of FIG. 17, the input side second electromagnetic valve 365 (2) and the output side second electromagnetic valve The friction plate of the clutch mechanism (in the example of FIG. 17, the input side second clutch mechanism 60 (2) and the output side second clutch mechanism 80 (2)) supplied with pressure oil via 367 (2)). The group gradually frictionally engages while sliding, just before the hydraulic pressure of the clutch mechanism reaches the engaging hydraulic pressure and the clutch mechanism becomes fully engaged, and before switching between the first and second transmission states. The clutch mechanism in the state (in the example of FIG. 17, the input side first clutch mechanism 60 (1) and the output side first clutch mechanism 80 (1)) is released from the engaging hydraulic pressure.

Therefore, while preventing or reducing as much as possible a state in which the traveling driving force is not transmitted to the drive wheels 220 when switching between the first and second transmission states, the switching between the first and second transmission states is further performed. It is possible to effectively prevent or reduce switching shocks and damage to the transmission system that may occur at times.

In the present embodiment, at the time of switching between the first and second transmission states, one of the solenoid valves that was located at the supply position at the time before switching is maintained at the supply position, and the time before switching is maintained. The other solenoid valve located at the discharge position is moved from the discharge position to the supply position, and the hydraulic pressure of the supply / discharge line supplied with pressure oil via the other solenoid valve becomes the switching hydraulic pressure P lower than the engaging hydraulic pressure. When the arrival is recognized based on the signal from the corresponding pressure sensor, the configuration for moving the one solenoid valve from the supply position to the discharge position is configured by the input side first and second clutch mechanisms 60 (1). Although it is applied to both the input side clutch unit formed by 60 (2) and the output side clutch unit formed by the output side first and second clutch mechanisms 80 (1) and 80 (2). Of course, the present invention is not limited to such a form, and the above-mentioned input side clutch unit on the side where a difference in rotational speed occurs due to the setting of the number of teeth of the gears constituting the transmission mechanism and the like. It is also possible to apply the clutch unit only to one of the output side clutch units, and if there is no possibility of the other, adopt the dog clutch type shown in FIG. 10 to reduce the cost.

It is also possible to apply this embodiment to the transmission structure 2 according to the second embodiment.

In the fifth and sixth embodiments, when the first and second transmission states are switched, the hydraulic pressure of the clutch mechanism (hereinafter, referred to as the pre-switching engaging clutch mechanism) that was in the engaged state before the switching is engaged. The clutch mechanism is lowered from the hydraulic pressure at a substantially constant rate to release it, but instead, as shown in FIG. 18, the clutch mechanism that was in the disengaged state before switching (hereinafter, the disengaged clutch mechanism before switching). The hydraulic pressure of the pre-switching engagement clutch mechanism is lowered at a substantially constant rate according to the hydraulic pressure of the switching hydraulic pressure P, and when the hydraulic pressure of the pre-switching shutoff clutch mechanism reaches the engaging hydraulic pressure, switching is performed. It is also possible to improve the durability of the friction plate by reducing the hydraulic pressure of the front engaging clutch mechanism to the release hydraulic pressure at once to reduce the time of unnecessary sliding transmission state.

Further, also in the fifth and sixth embodiments, the pressure sensors 370 (1), 370 (2), 372 (1), and 372 (2) are configured to detect the engaged state of the corresponding friction plate type clutch mechanism. Instead, the friction corresponding by other clutch engagement detecting means for detecting the supply current value, supply current time, etc. to the proportional solenoid valves 365 (1), 365 (2), 367 (1), and 367 (2). It is also possible to adopt a configuration that detects the engaged state of the plate type clutch mechanism.

Embodiment 7
Hereinafter, other embodiments of the transmission structure according to the present invention will be described with reference to the accompanying drawings.
FIG. 19 shows a schematic transmission diagram of the work vehicle 202 to which the transmission structure 7 according to the present embodiment is applied.
Further, FIG. 20 shows a hydraulic circuit diagram of the transmission structure 7 according to the present embodiment.
In the figure, the same members as in the embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

The transmission structure 1 according to the first embodiment is configured to switch the driving force forward and reverse by the forward / backward switching mechanism 230 arranged on the downstream side in the transmission direction from the speed change output shaft 45.

That is, as shown in FIG. 1, the transmission structure 1 according to the first embodiment has the speed change output shaft 45 and the traveling transmission shaft 235 that is operably rotationally driven by the rotational power of the speed change output shaft 45. In between, the forward / backward switching mechanism 230 for switching the rotation direction of the driving force between the forward direction and the reverse direction is provided.

On the other hand, the transmission structure 7 according to the present embodiment is capable of switching the rotation direction of the driving force transmitted to the speed change output shaft 45 in the forward and reverse directions.

Specifically, as shown in FIG. 19, the transmission structure 7 includes the HST 10, the planetary gear mechanism 30, and the input-side first and second transmission mechanisms 50 (1) and 50 (2). The output-side first transmission mechanism capable of transmitting the rotational power of the input-side first and second clutch mechanisms 60 (1) and 60 (2) and the second element to the speed change output shaft 45 in a normal rotation state. 70 (1) (forward first transmission mechanism) and the output side second transmission mechanism 70 (2) (forward second transmission mechanism) capable of transmitting the rotational power of the first element to the shift output shaft 45 in a normal rotation state. The transmission mechanism), the reverse transmission mechanism 70 (R) capable of transmitting the rotational power of the second element to the shift output shaft 45 in the reverse state, and the output side first transmission mechanism 70 (1) (the forward first). 1 transmission mechanism), the output side second clutch mechanism 70 (2) (the forward second transmission mechanism), and the output side first clutch mechanism 80 (1) that engages and disengages the power transmission of the reverse transmission mechanism 70 (R), respectively. 1) (forward first clutch mechanism), the output side second clutch mechanism 80 (2), the reverse clutch mechanism 80 (R), the speed change operation member 90, the HST sensor 95a, the output sensor 95b, and the like. It is provided with the control device 100.

The reverse transmission mechanism 70 (R) includes a reverse drive gear 72 (R) supported by the shift intermediate shaft 43 so as to be relatively non-rotatable, and a reverse drive gear 74 (R) supported by the shift output shaft 45 so as to be relatively rotatable. It has a reverse drive gear 72 (R) and a reverse idle gear 73 (R) meshed with the reverse drive gear 74 (R).

The reverse clutch mechanism 80 (R) has a reverse clutch housing 82 (R) supported by the speed change output shaft 45 so as to be relatively non-rotatable, and a reverse drive driven by the reverse driven gear 74 (R) so as not to be relatively rotatable. A reverse friction plate group 84 (R) including a reverse driven side friction plate supported by the reverse clutch housing 82 (R) so as to be relatively non-rotatable while facing the side friction plate and the reverse drive side friction plate, and the above. It has a reverse piston (not shown) that frictionally engages the reverse friction plate group 84 (R).

Reference numeral 105 in FIG. 19 is a solenoid valve unit including the input-side first solenoid valve 365 (1) and the like.
Reference numeral 242 in FIG. 19 is an auxiliary transmission mechanism including a friction plate type clutch mechanism, which is provided in place of the auxiliary transmission mechanism 240 including the dog clutch type clutch mechanism in the transmission structure 1 according to the first embodiment. ing.

The control device 100
When the speed change operation member 90 is located between the zero speed position and the switching speed position (that is, the rotation speed of the speed change output shaft 45 based on the detection signals of the HST sensor 95a and the output sensor 95b). In the low speed state from zero speed to less than the switching speed in the forward direction), the first forward clutch mechanism 60 (1) on the input side and the first clutch mechanism 80 (1) on the output side are engaged with each other. Make the transmission state appear,
When the speed change operation member 90 is operated beyond the switching speed position (that is, when the rotation speed of the speed change output shaft 45 is higher than the switching speed in the forward direction), the input side second A forward second transmission state in which the clutch mechanism 60 (2) and the output side second clutch mechanism 80 (2) are engaged is brought out, and
When the speed change operation member 90 is operated from the zero speed position to the reverse side (that is, in the reverse transmission state where the rotation speed of the speed change output shaft 45 changes from the zero speed to the reverse side), the input The reverse transmission state in which the side first clutch mechanism 60 (1) and the reverse clutch mechanism 80 (R) are engaged is brought out.

FIG. 21 shows a graph showing the relationship between the traveling vehicle speed and the HST output in the work vehicle 202 to which the transmission structure 7 according to the present embodiment is applied.
21 (a) and 21 (b) are graphs of the state in which the auxiliary transmission mechanism 242 is engaged with the low speed stage and the high speed stage, respectively.

As shown in FIG. 21, in the forward first transmission state, the HST output of the control device 100 shifts from the first HST speed to the second HST speed in response to the forward speed increasing operation of the speed change operation member 90. The output adjusting member 20 is operated as described above.

That is, when the speed change operation member 90 is operated between the zero speed position and the forward side switching speed position, the control device 100 makes the forward first transmission state appear, and then the speed change operation. The output adjusting member 20 is operated so that the HST output shifts from the first HST side to the second HST side as the member 90 is accelerated from the zero speed position side to the forward switching speed position side.

In the forward second transmission state, the control device 100 shifts the HST output from the second HST speed to the first HST speed in response to the forward speed increasing operation of the speed change operation member 90. To operate.

That is, when the control device 100 recognizes that the speed change operation member 90 has been operated from the zero speed position side to the forward side switching speed position, the control device 100 switches from the forward side first transmission state to the forward second transmission state. When the speed change operation member 90 is positioned on the forward high speed side from the forward side switching speed position, the forward second transmission state is displayed, and then the speed increase operation on the forward side of the speed change operation member 90 is performed. Correspondingly, the output adjusting member 20 is operated so that the HST output shifts from the second HST speed to the first HST speed.

In the reverse transmission state, the control device 100 operates the output adjusting member 20 so that the HST output shifts from the first HST speed to the second HST speed in response to the reverse speed increasing operation of the speed change operating member 90. Let me.

That is, when the speed change operation member 90 is operated from the zero speed position to the reverse side, the control device 100 makes the reverse transmission state appear, and then the speed change operation member 90 is operated to increase the speed backward. The output adjusting member 20 is operated so that the HST output shifts from the first HST side to the second HST side.

As shown in FIG. 21, also in the present embodiment, as in the case of the first embodiment, there is a speed difference between the traveling speed (that is, the speed change output shaft 45) when switching between the first and second transmission states on the forward side. Is configured so that

Specifically, the gear ratio of the input side first transmission mechanism 50 (1) (input side first gear ratio) and the gear ratio of the input side second transmission mechanism 50 (2) (input side second gear ratio). Is transmitted via the input-side second transmission mechanism 50 (2) in the forward second transmission state and the rotation speed of the second element when the HST output is set to the second HST speed in the forward first transmission state. The rotational speed of the first element and the forward first transmission state when the rotational speed of the second element due to the rotational power is the same and the HST output is the second HST speed in the forward second transmission state. At this time, the rotation speed of the first element due to the rotational power transmitted via the input-side first transmission mechanism 50 (1) is set to be the same.

Further, the gear ratio (forward first gear ratio) of the output side first transmission mechanism 70 (1) (forward first transmission mechanism) and the output side second transmission mechanism 70 (2) (forward second transmission mechanism). The gear ratio (forward second gear ratio) is set so that the rotational speeds appearing on the gear shifting output shaft 45 when the HST output is set to the second HST speed are the same in the first and second transmission states. ing.

With such a configuration, it is effectively prevented or reduced that a difference in rotational speed occurs in the speed change output shaft 45 when switching between the first and second transmission states on the forward side, that is, a difference in traveling speed occurs.

Further, when the HST output is set to the first HST speed in the engaged state of the input side first clutch mechanism 60 (1), the HST 10 and the planet are set so that the rotation speed of the second element becomes zero speed. The gear mechanism 30 is set.
According to such a configuration, it is possible to switch the vehicle forward and backward without difficulty. In particular, this configuration is effective in the case of a work vehicle that frequently performs work that requires forward / backward switching.

Next, the pressure oil supply / discharge configuration of the transmission structure 7 will be described.
As shown in FIG. 20, the transmission structure 7 includes the pressure oil supply line 155, the input side first supply / discharge line 360 (1), the input side second supply / discharge line 360 (2), and the above. The output side first supply / discharge line 362 (1) (forward side first supply / discharge line), the output side second supply / discharge line 362 (2) (forward side second supply / discharge line), and the reverse clutch mechanism 80. A reverse supply / discharge line 364 for supplying / discharging pressure oil to (R), a forward supply line 310 (F), a reverse supply line 310 (R), and the input side first solenoid valve 365 (1). , The input side second solenoid valve 365 (2), the output side first solenoid valve 367 (1), the output side second solenoid valve 367 (2), and the input side first pressure sensor 370 (1). To the input side second pressure sensor 370 (2), the output side first pressure sensor 372 (1), the output side second pressure sensor 372 (2), and the input side first supply / discharge line 360 (1). It includes a check valve 320 inserted, a pilot valve 330 inserted in the reverse supply line 310 (R), the drain line 157, and a forward / backward switching solenoid valve 300.

In the present embodiment, the input side first solenoid valve 365 (1), the input side second solenoid valve 365 (2), the output side first solenoid valve 367 (1), and the output side second solenoid valve The 367 (2) includes the forward supply line 310 (F), the input side first supply / discharge line 360 (1), the input side second supply / discharge line 360 (2), and the output side first supply / discharge line. It is inserted between each of the 362 (1) (first supply / discharge line on the forward side) and the second supply / discharge line 362 (2) (advance side second supply / discharge line) on the output side, and is located at the discharge position. When positioned, the corresponding supply / discharge lines 360 (1), 360 (2), 362 (1), 362 (2) are drained, while when positioned at the supply position, the corresponding supply / discharge lines 360 (1) The 360 (2), 362 (1), and 362 (2) are fluidly connected to the forward supply line 310 (F).

The forward / backward switching solenoid valve 300 is position-controlled by the control device 100, the forward supply line 310 (F) is fluidly connected to the pressure oil supply line 155, and the reverse supply line 310 (R) is connected. The forward position F for fluid connection to the drain line 157 and the reverse supply line 310 (R) are fluidly connected to the pressure oil supply line 155, and the forward supply line 310 (F) is fluidly connected to the drain line 157. It is now possible to take a reverse position R to cause the pressure oil supply line 155, a neutral position N to fluidly connect the forward supply line 310 (F) and the reverse supply line 310 (R) to the drain line 157. ing.

In the check valve 320, the pressure oil supplied from the forward supply line 310 (F) via the input side first solenoid valve 365 (1) is directed toward the input side first clutch mechanism 60 (1). It is inserted in the input side first supply / discharge line 360 (1) so as to prevent the flow in the pressure oil discharge direction in the opposite direction while allowing the flow in the pressure oil supply direction.

In the reverse supply line 310 (R), the upstream side close to the hydraulic source 150 is fluidly connected to the secondary side of the forward / backward switching solenoid valve 300, and the downstream side opposite to the hydraulic source 150 is said. A fluid is connected to the input side first supply / discharge line 360 (1) on the downstream side in the pressure oil supply direction from the check valve 320.

The pilot valve 330 has a communication position for communicating the reverse supply line 310 (R) and the reverse direction while allowing the pressure oil of the reverse supply line 310 (R) to flow in the pressure oil supply direction. It is configured so that it can selectively take a check position to prevent flow.

The pilot valve 330 is urged toward the communication position by the urging member 332, and uses the hydraulic pressure of the forward supply line 310 (F) as the pilot pressure, and pressurizes the forward supply line 310 (F). Is supplied, it is configured to be positioned at the check valve position against the urging force of the urging member 332.

The reverse supply / discharge line 364 is fluidly connected to the reverse supply line 310 (R) on the upstream side in the pressure oil supply direction from the pilot valve 330, and the downstream side is fluid to the reverse clutch mechanism 80 (R). It is connected.

The pressure oil supply / discharge configuration of the transmission structure 7 operates as follows.
When the speed change operation member 90 is positioned at the zero speed position, the control device 100 positions the forward / backward switching solenoid valve 300 at the neutral position.

In this state, the input side first supply / discharge line 360 (1), the input side second supply / discharge line 360 (2), the output side first supply / discharge line 362 (1), and the output side second supply / discharge line 362 (1). The discharge line 362 (2) and the reverse feed / discharge line 364 are all opened, and all the clutch mechanisms 60 (1), 60 (2), 80 (1), 80 (2), and 80 (R) are in a cutoff state. Therefore, power is not transmitted to the speed change output shaft 45.

When the speed change operating member 90 is operated to the forward side, the control device 100 positions the forward / backward switching solenoid valve 300 at the forward position F prior to the HST 10 outputting the first HST speed.

As a result, the reverse supply line 310 (R) is fluidly connected to the drain line 157, and the forward supply line 310 (F) is fluidly connected to the pressure oil supply line 155.

At this time, the pilot valve 330 is positioned at the check valve position by the hydraulic pressure of the forward supply line 310 (F). Therefore, the first supply / discharge line 360 (1) on the input side is in a state where the hydraulic pressure is held.

When the speed change operation member 90 is operated between the zero speed position and the forward side switching speed position, the control device 100 uses the input side first solenoid valve 365 (1) and the output side first. The solenoid valve 367 (1) is positioned at the supply position.

As a result, pressure oil flows into the input side first supply / discharge line 360 (1) and the output side first supply / discharge line 362 (1) from the forward supply line 310 (F), and the input side first clutch A forward first transmission state in which the mechanism 60 (1) and the output side first clutch mechanism 80 (1) are engaged is displayed.

At this time, the input side second supply / discharge line 360 (2) and the output side second supply / discharge line 362 (2) are drained by the corresponding solenoid valves 365 (2) and 367 (2). The reverse supply / discharge line 364 is drained via the reverse supply / supply line 310 (R) and the forward / backward switching solenoid valve 300.

When the speed change operation member 90 is operated to the forward high speed side beyond the forward side switching speed position, the control device 100 receives the input side first solenoid valve 365 prior to the HST 10 outputting the second HST speed. While the (1) and the output side first solenoid valve 367 (1) are positioned at the discharge position, the input side second solenoid valve 365 (2) and the output side second solenoid valve 367 (2) are positioned at the supply position. To position.

As a result, pressure oil flows into the input side second supply / discharge line 360 (2) and the output side second supply / discharge line 362 (2) from the forward supply line 310 (F), and the input side second clutch A forward second transmission state in which the mechanism 60 (2) and the output side second clutch mechanism 80 (2) are engaged is displayed.

At this time, the input side first supply / discharge line 36 (1) and the output side first supply / discharge line 362 (1) are drained via the corresponding solenoid valves 365 (1) and 367 (1). The reverse feed / discharge line 364 is drained via the reverse supply / supply line 310 (R) and the forward / backward switching solenoid valve 300.

When the speed change operation member 90 is operated to the reverse side, the control device 100 positions the forward / backward switching solenoid valve 300 at the reverse position R prior to the HST 10 outputting the first HST speed.

As a result, the forward supply line 310 (F) is fluidly connected to the drain line 157, and the reverse supply line 310 (R) is fluidly connected to the pressure oil supply line 155.

At this time, the input side first solenoid valve 365 (1), the input side second solenoid valve 365 (2), the output side first solenoid valve 367 (1), and the output side second solenoid valve 367 (2). Are all located in the discharge position.
Therefore, the input side second supply / discharge line 360 (2), the output side first supply / discharge line 362 (1), and the output side second supply / discharge line 362 (2) are the corresponding solenoid valves 365 (2). It is opened by 367 (1) and 367 (2).

On the other hand, the input-side first supply / discharge line 360 (1) is fluidly connected to the reverse supply line 310 (R) on the downstream side in the pressure oil supply direction from the check valve 320.
Therefore, although the input-side first solenoid valve 365 (1) is located at the discharge position, pressure is applied to the input-side first supply / discharge line 360 (1) via the reverse supply line 310 (R). Oil is supplied, and the input-side first clutch mechanism 60 (1) is engaged.

At this time, the pilot valve 330 whose pilot pressure is the hydraulic pressure of the forward supply line 310 (F) has the urging member 332 because the forward supply line 310 (F) is open. It is positioned in the communication position by the urging force.
Therefore, the pressure oil is effectively supplied to the input side first supply / discharge line 360 (1) via the reverse supply line 310 (R).

Further, as described above, the reverse supply / discharge line 364 is fluidly connected to the reverse supply line 310 (R) on the upstream side in the pressure oil supply direction from the pilot valve 300, and the reverse supply / discharge line 310 (R). ) Is supplying pressure oil.
As a result, a reverse transmission state in which the reverse clutch mechanism 80 (R) is engaged while the input-side first clutch mechanism 60 (1) is engaged is displayed.

It should be noted that the switching control timing of the input side first solenoid valve 365 (1) and the input side second solenoid valve 365 (2) when switching the forward side first and second transmission states, and the output side first. Regarding the switching control timing of the solenoid valve 367 (1) and the output side second solenoid valve 367 (2), various embodiments such as the third embodiment, the fifth embodiment and the sixth embodiment Can be applied.

As shown in FIG. 20, in the present embodiment, the input side first clutch mechanism 60 (1), the input side second clutch mechanism 60 (2), and the output side first clutch mechanism 80 (1). The output side second clutch mechanism 80 (2) and the reverse clutch mechanism 80 (R) are all hydraulically actuated friction plate type.

Instead of this, at least one of the input side clutch unit formed by the input side first and second clutch mechanisms and the output side clutch unit formed by the output side first and second clutch mechanisms is used in the above-described embodiment. It is also possible to use the dog clutch type in the fourth form.

FIG. 22 shows a hydraulic circuit diagram of the transmission structure 7B according to a modified example of the present embodiment.
In the drawings, the same members as in each of the above embodiments are designated by the same reference numerals, and the description thereof will be omitted.

Compared to the transmission structure 7 according to the present embodiment, the transmission structure 7B is a dog clutch type, instead of the friction plate type first and second input side clutch mechanisms 60 (1) and 60 (2). It has an input side clutch unit 410.

As a matter of course, instead of the output side first and second clutch mechanisms 80 (1) and 80 (2), a dog clutch type output side clutch unit 430 can be provided, and the reverse clutch mechanism 80 ( Instead of R), it is also possible to provide a dog clutch type clutch mechanism.

Embodiment 8
Hereinafter, other embodiments of the transmission structure according to the present invention will be described with reference to the accompanying drawings.
FIG. 23 shows a schematic transmission diagram of the work vehicle 203 to which the transmission structure 8 according to the present embodiment is applied.
Further, FIG. 24 shows a partial longitudinal side view of the work vehicle 203.
In the figure, the same members as in the embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

As shown in FIG. 23, the transmission structure 8 according to the present embodiment further has an output side third transmission mechanism 70 (3) and an output side as compared with the transmission structure 1 according to the first embodiment. It is equipped with a third clutch mechanism 80 (3).

That is, the transmission structure 8 includes the HST 10, the planetary gear mechanism 30, the speed change output shaft 45, the input side first and second transmission mechanisms 50 (1), 50 (2), and the input side. The first and second clutch mechanisms 60 (1) and 60 (2), the output side first to third transmission mechanisms 70 (1) to 70 (3), and the output side first to third clutch mechanisms 80. (1) to 80 (3), the speed change operation member 90, the HST sensor 95a, the output sensor 95b, and the control device 100 are provided.
In the present embodiment, the clutch mechanisms 60 (1), 60 (2), 80 (1) to 80 (3) are hydraulically operated friction plate type clutch units.

The output-side third transmission mechanism 70 (3) uses the rotational power of the first element (the internal gear 36 in the present embodiment) as the output-side second transmission mechanism 70 (2) of the output-side second transmission mechanism 70 (2). It is said that the operation can be transmitted to the shift output shaft 45 at the third gear ratio on the output side that rotates the shift output shaft 45 at a higher speed than the gear ratio.

The output-side third clutch mechanism 80 (3) is configured to engage and disengage the power of the output-side third transmission mechanism 70 (3).

FIG. 25 shows a graph showing the relationship between the traveling vehicle speed and the HST output in the work vehicle 203 to which the transmission structure 8 according to the present embodiment is applied.

As shown in FIG. 25, in the present embodiment, the control device 100 is
When the speed change operation member 90 is located between the zero speed position and the first switching speed position (that is, the speed change output shaft 45 is based on the detection signals of the HST sensor 95a and the output sensor 95b). (In a low speed state from zero speed to less than the first switching speed), the input side first clutch mechanism 60 (1) is engaged and the input side second clutch mechanism 60 (2) is cut off. The first transmission state in which the output side first clutch mechanism 80 (1) is engaged and the remaining output side second and third clutch mechanisms 80 (2) and 80 (3) are in a cutoff state. To appear,
When the speed change operation member 90 is positioned between the first switching speed position and the second switching speed position (that is, the speed change output shaft is based on the detection signals of the HST sensor 95a and the output sensor 95b). In the intermediate speed state from the first switching speed to the second switching speed), the input side first clutch mechanism 60 (1) is in the cutoff state and the input side second clutch mechanism 60 (2) Is engaged, the output side second clutch mechanism 80 (2) is engaged, and the remaining output side first and third clutch mechanisms 80 (1) and 80 (3) are disconnected. Make the second dynamic state appear,
When the speed change operation member 90 is operated beyond the second switching speed position (that is, the rotation speed of the speed change output shaft 45 is the second based on the detection signals of the HST sensor 95a and the output sensor 95b). In a high-speed state exceeding the switching speed), the output side third clutch is engaged while the input side first clutch mechanism 60 (1) is in the cutoff state and the input side second clutch mechanism 60 (2) is in the engaged state. A third transmission state is manifested in which the mechanism 80 (3) is engaged and the remaining first and second clutch mechanisms 80 (1) and 80 (2) on the output side are shut off.

As shown in FIG. 23, the transmission structure 8 has the forward / backward switching mechanism 230 inserted between the speed change output shaft 45 and the traveling transmission shaft 235, and the forward / backward switching mechanism The output of 230 is operated and transmitted to the traveling transmission shaft 235.

Then, the control device 100 puts the forward / backward switching mechanism 230 into the forward transmission state and the reverse transmission state, respectively, in response to the operation of the speed change operation member 90 to the forward side and the reverse side.

That is, in the work vehicle 203, when the speed change operation member 90 is operated between the zero speed position and the forward side first switching speed position, the forward first transmission state appears, and the speed change operation When the member 90 is positioned at the first switching speed position on the forward side, the traveling transmission shaft 235 rotates at a rotational speed that makes the traveling vehicle speed + a.

When the speed change operation member 90 is operated between the forward side first switching speed position and the forward side second switching speed position, the forward second transmission state appears, and the speed change operation member 90 is on the forward side. When the traveling transmission shaft 235 is positioned at the second switching speed position, the traveling transmission shaft 235 rotates at a rotational speed that makes the traveling vehicle speed + b.

Then, when the speed change operation member 90 is operated beyond the forward side second switching speed position, the forward third transmission state appears, and the speed change operation member 90 is positioned at the forward side maximum speed position. At this point, the traveling transmission shaft 235 rotates at a rotational speed that makes the traveling vehicle speed + c.

Similarly, when the speed change operation member 90 is operated between the zero speed position and the reverse side first switching speed position, the reverse first transmission state appears, and the speed change operation member 90 is on the reverse side first. When the traveling transmission shaft 235 is positioned at the switching speed position, the traveling transmission shaft 235 rotates at a rotational speed that makes the traveling vehicle speed −a.

When the speed change operation member 90 is operated between the reverse side first switching speed position and the reverse side second switching speed position, the reverse reverse second transmission state appears, and the speed change operation member 90 is on the reverse side. When the traveling transmission shaft 235 is positioned at the second switching speed position, the traveling transmission shaft 235 rotates at a rotational speed that makes the traveling vehicle speed −b.

Then, when the speed change operation member 90 is operated beyond the reverse side second switching speed position, the reverse third transmission state appears, and the speed change operation member 90 is positioned at the reverse side maximum speed position. At this point, the traveling transmission shaft 235 rotates at a rotational speed that makes the traveling vehicle speed −c.

As in the first embodiment, the input-side first gear ratio of the input-side first transmission mechanism 50 (1) and the input-side second gear ratio of the input-side second transmission mechanism 50 (2) are , The rotation speed of the second element (the carrier 38 in the present embodiment) when the HST output is set to the second HST speed in the first transmission state, and the input side second transmission mechanism in the second transmission state. The first element (this implementation) when the rotational speed of the second element due to the rotational power transmitted via 50 (2) is the same and the HST output is the second HST speed in the second transmission state. In the embodiment, the rotational speed of the internal gear 36) and the rotational speed of the first element due to the rotational power transmitted via the input-side first transmission mechanism 50 (2) in the first transmission state. It is set to be the same.

Further, as shown in FIG. 25, the output side first gear ratio of the output side first transmission mechanism 70 (1) and the output side second gear ratio of the output side second transmission mechanism 70 (2) are When the HST output is set to the second HST speed, the rotation speeds appearing on the speed change output shaft 45 are set to be the same in the first and second transmission states.

Further, as shown in FIG. 25, in the transmission structure 8 according to the present embodiment, when the control device 100 is switched between the second and third transmission states, the speed change output shaft 45 is in the transmission state after the switching. The output adjusting member 20 is configured to operate so that the rotation speed displayed in the above is equal to or close to the rotation speed appearing on the speed change output shaft 45 in the transmission state before switching.

That is, when the speed change operation member 90 is operated in the speed increasing direction to reach the second switching speed position under the second transmission state (when the rotation speed of the speed change output shaft 45 reaches the second switching speed), the control The device 100 shifts the output-side second clutch mechanism 80 (2) from the engaged state to the disengaged state, and shifts the output-side third clutch mechanism 80 (3) from the disengaged state to the engaged state. The output of the HST 10 is from the rotation speed (first HST speed) that rotates the shift output shaft 45 at the second switching speed under the second transmission state, to the second switching speed or the shift output shaft 45 under the third transmission state. The output adjusting member 20 is operated so as to shift to a rotation speed (third HST speed in FIG. 25) that rotates at a speed close to the rotation speed.

Further, when the speed change operation member 90 is operated in the deceleration direction to reach the second switching speed position under the third transmission state (when the rotation speed of the speed change output shaft 45 reaches the second switching speed), the control device Reference numeral 100 denotes the HST 10 while shifting the output side third clutch mechanism 80 (3) from the engaged state to the disengaged state and shifting the output side second clutch mechanism 80 (2) from the disengaged state to the engaged state. The output of is from the rotation speed (third HST speed) for rotating the shift output shaft 45 at the second switching speed under the third transmission state, to the second switching speed of the shift output shaft 45 under the second transmission state or its own. The output adjusting member 20 is operated so as to shift to a rotation speed (first HST speed) that is rotated in the vicinity.

According to the transmission structure 8 having such a configuration, the shiftable range (shift range) can be expanded while obtaining the same effect as the transmission structure according to the first embodiment.

In the present embodiment, as described above, when the HST output is set to the second HST speed, the rotational speeds appearing on the speed change output shaft 45 are the same in the first and second transmission states. The first and second gear ratios on the output side are set, but instead of this, when switching between the first and second transmission states, they appear on the shift output shaft 45 in the transmission state after switching. The control device 100 may be configured to operate the output adjusting member 20 so that the rotational speed matches or is close to the rotational speed displayed on the shift output shaft 45 in the transmission state before switching. It is possible.

As shown in FIGS. 23 and 24, the transmission structure 8 according to the present embodiment is connected to the second element (the carrier 38 in the present embodiment) so as not to rotate relative to the axis. The shaft 43 has a speed change transmission shaft 44 extrapolated so as to be relatively rotatable.

The speed change transmission shaft 44 is connected to the first element (the internal gear 36 in the present embodiment) so as not to rotate relative to the axis, and the input side first transmission mechanism 50 (1) is the same. The rotational power of the main drive shaft 212 is operated and transmitted to the first element via the gear shift transmission shaft 44, and the output side first and second transmission mechanisms 70 (1) and 70 (2) are the gear shift transmission shafts. It is configured to operate and transmit the rotational power of the first element to the speed change output shaft 45 via 44.

Specifically, as shown in FIGS. 23 and 24, in the present embodiment, the input-side first driven gear 54 (1) of the input-side first transmission mechanism 50 (1) is the main drive shaft 212. In a state of being operatively connected to the input side first drive gear 52 (1) supported so as to be relatively rotatable, the gear shift transmission shaft 44 is supported so as to be relatively non-rotatable.

Further, the output side second drive gear 72 (2) of the output side second transmission mechanism 70 (2) is operatively connected to the output side second driven gear 74 (2), and the speed change transmission shaft 44 It is supported so that it cannot rotate relative to each other.

The output-side third transmission mechanism 70 (3) is attached to the output-side third drive gear 72 (3) and the output-side third drive gear 72 (3), which are non-rotatably supported by the speed change transmission shaft 44. It has an output-side third driven gear 74 (3) that is operatively connected and supported relative to the speed change output shaft 45 so as to be relatively rotatable.

The input side second transmission mechanism 50 (2) and the input side second drive gear 52 (2) supported by the main drive shaft 212 so as to be relatively rotatable, as in the first embodiment. The second element has an input-side first driven gear 54 (2) that is operatively connected to the input-side second drive gear 52 (2) and is unable to rotate relative to the second element.

As shown in FIG. 24, the transmission structure 8 has a variable input shaft 31 that supports the third element (the sun gear 32 in the present embodiment) acting as the variable input unit so as to be non-rotatable relative to the axis. The input-side first driven gear 54 (2) is supported by the variable input shaft 31 so as to be relatively rotatable.

The variable input shaft 31 is supported by a driven gear 216b of the gear train 216 that operates and connects the rotational power of the motor shaft 16 to the third element (the sun gear 32) so as to be relatively non-rotatable.

In the present embodiment, the output side third clutch mechanism 80 (3) includes an output side clutch housing 83 supported by the speed change output shaft 45 so as not to rotate relative to the speed change output shaft 45, and the output side third driven gear 74 (3). ), And the third driven side friction plate supported by the output side clutch housing 83 in a state of facing the third drive side friction plate so as to be relatively non-rotatable. It has an output side third friction plate group 84 (3) including the output side third friction plate group 84 (3) and an output side third piston (not shown) for frictionally engaging the output side third friction plate group 84 (3).

As shown in FIG. 24, the transmission structure 8 according to the present embodiment is housed in the housing structure 500 of the work vehicle 203.

The housing structure 500 has a front housing 510 and a rear housing 550 that are connected in series.

The front housing 510 includes a hollow front housing main body 512, a front support wall 514 and a second support wall 518 extending radially inward from the inner surface at an intermediate position in the front-rear direction of the front housing main body 512, and the above. It has a front bearing plate 516 detachably connected to a boss portion formed so as to project radially inward from the inner surface in the vicinity of the rear opening of the front housing main body 512.

The rear housing 550 has a hollow rear housing body 552 detachably connected to the front housing body 512 and a boss portion formed so as to project radially inward from the inner surface in the vicinity of the front opening of the rear housing body 552. It has a rear bearing plate 554 detachably connected to the rear housing body 552 and a rear support wall 556 extending radially inward from the inner surface at an intermediate position in the front-rear direction of the rear housing main body 552.

In such a configuration, the main drive shaft 212 is rotatably supported around the axis by the front support wall 514, the front bearing plate 516, and the rear bearing plate 554, and the input side first and second clutch mechanisms. The 60 (1) and 60 (2) are supported by the main drive shaft 212 in the front housing main body 512. A successor cylinder portion 516a for supplying and discharging pressure oil to the first and second clutch mechanisms 60 (1) and 60 (2) on the input side is integrally formed with the front bearing plate 516 fitted to the main drive shaft 212. ing. The input-side first and second supply / discharge lines 360 (1) and 360 (2) shown in FIG. 16 described above are connected to the successor cylinder portion 516a by means such as a pipe.

The variable input shaft 31 is a hollow shaft integrally formed at the rotation center of the driven gear 216b, and its front end side is rotatably supported by the front support wall 514 around the axis.
The sun gear shaft 32a integrally having the sun gear 32 on the rear end side has a front end side inserted into the rear end side of the variable input shaft 31 and spline-connected, and the input side second driven gear 54 at the center portion. (2) is supported so as to be relatively rotatable.

The shift intermediate shaft 43 is arranged coaxially with the variable input shaft 31 and the sun gear shaft 32a. The transmission intermediate shaft 43 integrally has the carrier 38 on the front end side, and the carrier 38 is connected to the input side second driven gear 54 (2) via a bolt. As a result, the front end side of the shift intermediate shaft 43 is rotatably supported by the front bearing plate 516 via the sun gear shaft 32a and the shift input shaft 31, and is supported on the rear end side of the shift intermediate shaft 43. Is rotatably supported around the axis by the rear bearing plate 554.

The hollow transmission transmission shaft 44, which is extrapolated to the transmission intermediate shaft 43 so as to be relatively rotatable, has the internal gear 36 integrally at the front end portion, and the front end side is interposed via the transmission intermediate shaft 43. It is supported by the front support wall 514, and the rear end side is supported by the front bearing plate 516. Then, on the outer circumference of the intermediate portion of the transmission transmission shaft 44 from the internal gear 36 to the front bearing plate 516, the output side third drive gear 72 (3) and the input side first driven gear 54 (1) ), The output side second drive gear 72 (2) is spline-fitted.

The speed change output shaft 45 is rotatably supported around the axis by the second support wall 518, the rear bearing plate 554, and the rear support wall 556. The first traveling transmission shaft 235 is rotatably supported around the axis by the rear bearing plate 554 and the rear support wall 556.

The speed change output shaft 45 has the output side third clutch mechanism 80 (3) on the front end side, and the output side first and second clutch mechanisms 80 (1) and 80 (2) on the rear end side in the intermediate portion. Supports the clutch mechanism of the forward / backward switching mechanism 230, respectively. A hydraulically operated friction plate type clutch unit is also used for the clutch mechanism of the forward / backward switching mechanism 230. A succession cylinder portion 556a for supplying and discharging pressure oil to these five clutch mechanisms arranged on the shift output shaft 45 is mounted on the rear support wall 556 and is covered at the rear end portion of the shift output shaft 45. It is fitted.

The differential mechanism 260, the PTO clutch mechanism 285, and the PTO multi-speed transmission mechanism 290 are housed in the latter half of the rear housing 550 (not shown).

In the present embodiment, the input side first and second clutch mechanisms 60 (1) and 60 (2), and the output side first to third clutch mechanisms 80 (1) to 80 (3). All of these are of the friction plate type, but it is also possible to make some or all of them the dog clutch type.

FIG. 26 shows a modified example of the present embodiment in which the input side clutch unit 410 of the dog clutch type is provided instead of the friction plate type first and second input side clutch mechanisms 60 (1) and 60 (2). A schematic transmission diagram of the work vehicle 203 to which the transmission structure 8B is applied is shown.

Embodiment 9
Hereinafter, other embodiments of the transmission structure according to the present invention will be described with reference to the accompanying drawings.
FIG. 27 shows a schematic transmission diagram of the work vehicle 205 to which the transmission structure 9 according to the present embodiment is applied.
Further, FIG. 28 shows a partial longitudinal side view of the work vehicle 205.
In the figure, the same members as in the embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

The transmission structure 9 according to the present embodiment is common to the transmission structure 8 according to the eighth embodiment in that the output side first to third clutch mechanisms 80 (1) to 80 (3) are provided. are doing.

On the other hand, the transmission structure 9 is different from the transmission structure 8 according to the eighth embodiment in the following points.

That is, the transmission structure 8 according to the eighth embodiment is the first to third transmissions that appear depending on the engaging states of the output side first to third clutch mechanisms 80 (1) to 80 (3). In all of the states, the rotational power is transmitted to the traveling transmission shaft 235 via the forward / backward switching mechanism 230.

On the other hand, in the transmission structure 9 according to the present embodiment, the first and second clutch mechanisms 80 (1) and 80 (2) on the output side are exposed by the engaging states of the first and second clutch mechanisms 80 (1) and 80 (2). In the transmission state, the rotational power is transmitted to the traveling transmission shaft via the forward / backward switching mechanism 230, while the third transmission appears in the engaged state of the output side third clutch mechanism 80 (3). In the state, it is configured to transmit the rotational power in the forward direction to the traveling transmission shaft 235 without going through the forward / backward switching mechanism 230.

Specifically, as shown in FIG. 27, the transmission structure 9 applies the rotational power of the HST 10, the planetary gear mechanism 30, and the drive source 210 to the first element (this implementation) at the input side first gear ratio. In the embodiment, the input side first transmission mechanism 750 (1) capable of transmitting the operation to the internal gear 36) and the second element (the carrier 38 in the present embodiment) are operated by the input side second gear ratio. The input side second transmission mechanism 750 (2) capable of transmission, the input side first and second clutch mechanisms 60 (1) and 60 (2), the shift output shaft 45 and the traveling transmission shaft 235, and the above. The forward / backward switching mechanism 230, the output side first transmission mechanism 770 (1) capable of transmitting the rotational power of the second element to the shift output shaft 45 at the output side first gear ratio, and the rotation of the first element. The output side second transmission mechanism 770 (2) capable of transmitting power to the shift output shaft 45 at the output side second gear ratio, and the driving force in the forward direction to transmit the rotational power of the first element to the traveling transmission shaft 235. The output side third transmission mechanism 770 (3), the output side first to third clutch mechanisms 80 (1) to 80 (3), the speed change operation member 90, and the HST sensor 95a. , The control device 100 is provided.

As shown in FIGS. 27 and 28, the transmission structure 9 further has the speed change intermediate shaft 43 connected to the second element (the carrier 38 in the present embodiment) so as to be non-rotatably connected around the axis. ing.
Further, the transmission structure 9 has an output sensor 95b that directly or indirectly detects the rotational speed of the traveling transmission shaft 235.

The input-side first transmission mechanism 750 (1) includes an input-side first drive gear 752 (1) rotatably supported by a main drive shaft 212 operably connected to the drive source 210, and the shift intermediate shaft. The input side first drive gear 752 (1) and the first element (in the present embodiment, the internal gear 36) are operatively connected to the input side first drive gear 752 (1) while being supported by the 43 so as to be relatively rotatable. It has a driven gear 754 (1).

The input-side second transmission mechanism 750 (2) is supported by the input-side second drive gear 752 (2) rotatably supported by the main drive shaft 212 and the shift intermediate shaft 43 so as not to rotate relative to each other. In this state, it has an input side second driven gear 754 (2) that is operatively connected to the input side second drive gear 752 (2), and uses the rotational power of the main drive shaft 212 as the speed change intermediate shaft 43. The operation is transmitted to the second element (the carrier 38 in the present embodiment) via the above.

In this case, as shown in FIGS. 27 and 28, the input-side first and second clutch mechanisms 60 (1) and 60 (2) are the input-side first and second drive gears 752 (1), respectively. , 752 (2) are supported by the main drive shaft 212 so as to engage and disengage the main drive shaft 212.

That is, in the present embodiment, the input-side first clutch mechanism 60 (1) is attached to the input-side clutch housing 62 and the input-side clutch housing 62 supported by the main drive shaft 212 so as not to rotate relative to each other. The first driven side friction plate supported so as to be relatively non-rotatable and the first driven side supported so as to be relatively non-rotatable by the input side first drive gear 752 (1) while facing the first drive side friction plate. It is configured to have an input side first friction plate group 64 (1) including a friction plate and an input side first piston (not shown) for frictionally engaging the input side first friction plate group 64 (1). Will be done.

The input side second clutch mechanism 60 (2) is attached to the input side clutch housing 62, the second drive side friction plate supported by the input side clutch housing 62 so as not to rotate relative to the input side clutch housing 62, and the second drive side friction plate. The input side second friction plate group 64 (2) including the second driven side friction plate supported by the input side second drive gear 752 (2) so as to be opposed to each other, and the input side second friction plate group 64 (2). It is configured to have an input-side second piston (not shown) for frictionally engaging the friction plate group 64 (2).

In the present embodiment, the output side first transmission mechanism 770 (1) utilizes the input side second driven gear 754 (2) in the input side second transmission mechanism 750 (2) to use the first transmission side gear 754 (2). It is configured so that the rotational power of the two elements can be transmitted to the speed change output shaft 45.

Specifically, as shown in FIGS. 27 and 28, the output side first transmission mechanism 770 (1) is supported by the speed change output shaft 45 so as to be relatively rotatable, and the input side second driven gear 754 ( It has an output side first driven gear 774 (1) that is operatively connected to 2).

The output-side second transmission mechanism 770 (2) uses the input-side first driven gear 754 (1) in the input-side first transmission mechanism 750 (1) to generate the rotational power of the first element. It is configured so that the operation can be transmitted to the speed change output shaft 45.

Specifically, as shown in FIGS. 27 and 28, the output side second transmission mechanism 770 (2) is supported by the speed change output shaft 45 so as to be relatively rotatable, and the input side first driven gear 754 ( It has an output side second driven gear 774 (2) that is operatively connected to 1).

In this case, as shown in FIGS. 27 and 28, the output side first and second clutch mechanisms 80 (1) and 80 (2) have the output side first and second driven gears 774 (1), respectively. , 774 (2) is supported by the shift output shaft 45 so as to engage and disengage the shift output shaft 45.

That is, in the present embodiment, the output side first clutch mechanism 80 (1) has an output side clutch housing 82 supported by the speed change output shaft 45 so as not to rotate relative to the speed change output shaft 45, and the output side first driven gear 774. The first driven side friction plate supported by (1) so as to be relatively non-rotatable and the first driven side friction supported by the output side clutch housing 82 so as to be opposed to the first drive side friction plate. It is configured to have an output side first friction plate group 84 (1) including a plate and an output side first piston (not shown) for frictionally engaging the output side first friction plate group.

The output side second clutch mechanism 80 (2) includes the output side clutch housing 82, a second drive side friction plate supported by the output side second driven gear 774 (2) so as not to rotate relative to the output side clutch housing 82, and the second drive side friction plate. The output side second friction plate group 84 (2) including the second driven side friction plate supported by the output side clutch housing 82 so as to be relatively non-rotatable while facing the drive side friction plate, and the output side second friction plate group 84 (2). It is configured to have an output-side second piston (not shown) for frictionally engaging the friction plate group.

In the output-side third transmission mechanism 770 (3), the rotational power of the first element is transmitted to the traveling transmission shaft via the output-side second transmission mechanism 770 (2) and the forward / backward advance switching mechanism 230 in the forward transmission state. The rotational power of the first element is transmitted to the traveling transmission shaft 235 via the output side third transmission mechanism 770 (3) rather than the rotational speed of the traveling transmission shaft 235 when the operation is transmitted to the 235. The gear ratio is set so that the rotation speed of the traveling transmission shaft 235 becomes high.

In the present embodiment, the output-side third transmission mechanism 770 (3) utilizes the output-side second driven gear 774 (2) in the output-side second transmission mechanism 770 (2) to use the output-side second driven gear 774 (2). It is configured so that the rotational power of one element can be transmitted to the traveling transmission shaft 235.

Specifically, as shown in FIGS. 27 and 28, the output-side third transmission mechanism 770 (3) is supported by the traveling transmission shaft 235 so as to be relatively rotatable, and the output-side second driven gear 774 ( It has an output-side third driven gear 774 (3) that is operatively connected to 2).

In this case, as shown in FIGS. 27 and 28, the output side third clutch mechanism 80 (3) engages the output side third driven gear 774 (3) with the traveling transmission shaft 235. It is supported by the traveling transmission shaft 235.

That is, in the present embodiment, the output side third clutch mechanism 80 (3) has the output side clutch housing 83 supported by the traveling transmission shaft 235 so as not to rotate relative to the traveling transmission shaft 235, and the output side third driven gear. The third drive side friction plate supported by 774 (3) so as to be relatively non-rotatable, and the third driven side supported by the output side clutch housing 83 so as to be relatively non-rotatable while facing the third drive side friction plate. It is configured to have an output side third friction plate group 84 (3) including a friction plate and an output side third piston (not shown) for frictionally engaging the output side third friction plate group 84 (3). Has been done.

It is also possible to operate and connect the output side third driven gear 774 (3) to the output side first driven gear 774 (1) instead of the output side second driven gear 774 (2).

That is, the rotational power of the first element is operated and transmitted to the traveling transmission shaft 235 by using the output side first driven gear 774 (1) in the output side first transmission mechanism 770 (1). It is also possible to deform the output-side third transmission mechanism 770 (3).

FIG. 29 shows a graph showing the relationship between the traveling vehicle speed and the HST output in the work vehicle 205 to which the transmission structure 9 according to the present embodiment is applied.

As shown in FIG. 29, in the present embodiment, the control device 100 is
The output adjusting member 20 is operated so that the HST output becomes the first HST speed at which the combined rotational power of the planetary gear mechanism 30 is set to zero in response to the operation of the shifting operation member 90 to the zero speed position.
When the speed change operation member 90 is operated in the forward side low speed range from the zero speed position to the forward side first switching speed position, the input side first clutch mechanism 60 (1) is engaged. And while the input side second clutch mechanism 60 (2) is shut off, the first output side first clutch mechanism 80 (1) is engaged and the other output side clutch mechanisms 80 (2), 80 ( By setting 3) to the cutoff state, the first element acts as an input unit of the reference power operatively transmitted from the drive source 210, and the second element acts as an output unit of the combined rotational power. While exhibiting the first transmission state in which the combined rotational power output from the second element is transmitted to the shift output shaft 45, the forward / backward switching mechanism 230 is brought into the forward transmission state, and the shift operation member. The output adjusting member 20 is operated so that the HST output shifts from the side of the first HST speed to the side of the second HST speed in response to the speed increasing operation of 90.
When the speed change operation member 90 is operated in the forward side intermediate speed range between the forward side first switching speed position and the forward side second switching speed position, the input side first clutch mechanism 60 (1). ) Is in the cutoff state and the input side second clutch mechanism 60 (2) is in the engaged state, while the output side second clutch mechanism 80 (2) is in the engaged state and the other output side clutch mechanism 80 (1) is engaged. ), 80 (3) are set to the cutoff state, so that the second element acts as an input unit of the reference power and the first element acts as an output unit of the combined rotational power, and is output from the first element. While displaying the second transmission state in which the combined rotational power is transmitted to the shift output shaft 45, the forward / reverse advance switching mechanism 230 is brought into the forward transmission state, and the speed increase operation of the shift operation member 90 is performed. The output adjusting member 20 is operated so that the HST output shifts from the second HST speed side to the first HST speed side.
When the speed change operation member 90 is operated in the forward side high speed range exceeding the forward side second switching speed position, the input side first clutch mechanism 60 (1) is in the cutoff state and the input side second. While the clutch mechanism 60 (2) is engaged, the output-side third clutch mechanism 80 (3) is engaged and the other output-side clutch mechanisms 80 (1) and 80 (2) are engaged. As a result, the second element acts as an input unit for the reference power, the first element acts as an output unit for the combined rotational power, and the combined rotational power output from the first element is used as the output side third. While displaying a third transmission state in which the traveling transmission shaft 235 is transmitted as a driving force in the forward direction via the transmission mechanism 770 (3), the HST output is changed in response to the speed-increasing operation of the speed change operation member 90. The output adjusting member 20 is operated so as to shift from the 2 HST speed side to the 1st HST speed side.
When the speed change operation member 90 passes through the forward side second switching speed position between the forward side intermediate speed range and the forward side high speed range, the traveling transmission shaft in the transmission state that appears immediately after the passage. The output adjusting member 20 is operated so that the rotation speed of the 235 matches or approaches the rotation speed of the traveling output shaft 235 in the transmission state that appears immediately before passing.
When the speed change operation member 90 is operated in the reverse speed range from the zero speed position to the reverse side first switching speed position, the forward / backward switching is performed while displaying the first transmission state. The output adjusting member 20 is moved so that the mechanism 230 is in the reverse transmission state and the HST output is changed from the first HST speed side to the second HST speed side in response to the speed increasing operation of the speed change operation member 90. Activate,
When the speed change operation member 90 is operated in the reverse speed range exceeding the reverse reverse first switching speed position, the forward / backward switching mechanism 230 is moved to the reverse transmission state while displaying the second transmission state. The output adjusting member 20 is operated so that the HST output shifts from the side of the second HST speed to the side of the first HST speed in response to the speed increasing operation of the speed change operating member 90.

Similar to the first embodiment, the input side first transmission ratio of the input side first transmission mechanism 750 (1) and the second gear ratio of the input side second transmission mechanism 750 (2) are the first. The rotation speed of the second element (carrier 38 in the present embodiment) when the HST output is set to the second HST speed in the transmission state and the input side second transmission mechanism 750 (2) in the second transmission state. The first element (in the present embodiment) when the rotational speed of the second element due to the rotational power transmitted via) is the same and the HST output is set to the second HST speed in the second transmission state. The rotation speed of the internal gear 36) and the rotation speed of the first element due to the rotational power transmitted via the input side first transmission mechanism 750 (1) in the first transmission state are the same. Is set to.

Further, as shown in FIG. 29, the output side first gear ratio of the output side first transmission mechanism 770 (1) and the output side second gear ratio of the output side second transmission mechanism 770 (2) are HST outputs. Is set to be the same in the first and second transmission states as the rotation speed appearing on the shift output shaft 45 when is set to the second HST speed.

Then, as described above, when the speed change operation member 90 passes through the forward side second switching speed position between the forward side medium speed range and the forward side high speed range, the control device 100 appears immediately after the passage. The output adjusting member 20 is set so that the rotation speed of the traveling transmission shaft 235 in the transmitted transmission state matches or approaches the rotation speed of the traveling output shaft 235 in the transmission state that appears immediately before passing. Activate.

That is, when the speed change operation member 90 is operated in the speed increasing direction in the forward side intermediate speed range (second transmission state), passes through the forward side second switching speed position, and enters the forward side high speed range. The control device 100 shifts the output side second clutch mechanism 80 (2) from the engaged state to the disengaged state and shifts the output side third clutch mechanism 80 (3) from the disengaged state to the engaged state. While switching from the second transmission state to the third transmission state, the output of the HST 10 changes from the rotational speed (first HST speed) that makes the traveling vehicle speed + b under the second transmission state to the third transmission state. The output adjusting member 20 is operated so as to shift to a rotational speed (third HST speed) that causes the traveling vehicle speed to be + b or a speed close thereto.

Further, when the speed change operation member 90 is operated in the deceleration direction in the forward side high speed range (third transmission state), passes through the forward side second switching speed position, and enters the forward side intermediate speed range, the above. The control device 100 shifts the output side third clutch mechanism 80 (3) from the engaged state to the disengaged state and shifts the output side second clutch mechanism 80 (2) from the disengaged state to the engaged state. While switching from the third transmission state to the second transmission state, the output of the HST 10 changes from the rotational speed (third HST speed) that makes the traveling vehicle speed + b under the third transmission state under the second transmission state. The output adjusting member 20 is operated so as to shift to a rotational speed (first HST speed) that causes the traveling vehicle speed to be + b or a speed close thereto.

According to the transmission structure 9 having such a configuration, the shiftable range (shift range) on the forward side can be further expanded while obtaining the same effect as the transmission structure 1 according to the first embodiment.

In the present embodiment, as described above, the output-side first and second gear ratios are the same so that the traveling vehicle speed when the HST output is the second HST speed is the same in the first and second transmission states. Is set, but instead of this, when switching between the first and second transmission states, the traveling vehicle speed in the transmission state after switching matches or approaches the traveling vehicle speed in the transmission state before switching. In addition, the control device 100 can be configured to operate the output adjusting member 20.

The transmission structure 9 according to the present embodiment is housed in the housing structure 500B of the work vehicle 205.

As shown in FIG. 28, the housing structure 500B includes a hollow housing body 505B, a first bearing plate 516B detachably connected to the housing body 505B, and the housing body 505B from the first bearing plate 516B. It is provided with a second bearing plate 554B that is detachably connected to the housing body 505B at a position separated in the longitudinal direction and forms a partition space S with the first bearing plate 516B.

In the present embodiment, the housing body 505B has a front housing body 510B and a rear housing body 550B that are detachably connected in series.

The first bearing plate 516B is detachably connected to a boss portion 511 provided on the inner surface of the front housing main body 510B in the vicinity of the rear opening of the front housing main body 510B, and the second bearing plate 554B is detachably connected to the boss portion 511. Is detachably connected to a boss portion 551 provided on the inner surface of the rear housing main body 550B in the vicinity of the front opening of the rear housing main body 550B.

As shown in FIG. 28, the main drive shaft 212, the shift intermediate shaft 43, the shift output shaft 45, and the traveling transmission shaft 235 are parallel to each other and along the longitudinal direction of the housing body 505B. It is supported by the first and second bearing plates 516B and 554B.

The input side first and second drive gears 752 (1) and 752 (2) and the input side first and second clutch mechanisms 60 (1) and 60 (2) relate to the axial direction of the main drive shaft 212. With the input side first and second clutch mechanisms 60 (1) and 60 (2) positioned between the input side first and second drive gears 752 (1) and 752 (2), the main It is supported by a portion of the drive shaft 212 located in the compartment S.

The input side first and second driven gears 754 (1) and 754 (2) are located at the same positions as the input side first and second drive gears 752 (1) and 752 (2) in the axial direction, respectively. In this state, it is supported by a portion of the shift intermediate shaft 43 located in the partition space S.

The output side first and second driven gears 774 (1) and 774 (2) and the output side first and second clutch mechanisms 80 (1) and 80 (2) are the output side first and second driven gears. The gears 774 (1) and 774 (2) are positioned at the same positions as the input side second and first driven gears 754 (2) and 754 (1) in the axial direction, respectively, and the output side first and first gears are located. 2 With the clutch mechanisms 80 (1) and 80 (2) positioned between the input side first and second driven gears 774 (1) and 774 (2) in the axial direction, the speed change output shaft 45 Of these, it is supported by a portion located in the compartment S.

In the output side third driven gear 774 (3) and the output side third clutch mechanism 80 (3), the output side third driven gear 774 (3) is aligned with the output side second driven gear 774 (2). The output side third clutch mechanism 80 (3) is located at the same position in the direction, and the output side first and second clutch mechanism 80 (1) is based on the output side second driven gear 774 (2) in the axial direction. ), 80 (2), and is supported by a portion of the traveling transmission shaft 235 located in the compartment S.

The forward / backward switching mechanism 230 is supported by a portion of the shift output shaft 45 and the traveling transmission shaft 235 located outside the partition space S.

Specifically, as shown in FIGS. 27 and 28, the forward / backward switching mechanism 230 is supported by the forward drive gear 711F supported by the shift output shaft 44 and the traveling transmission shaft 235, and is supported by the forward drive gear. The forward gear row 710F including the forward driven gear 712F meshed with the 711F, the reverse drive gear 231R supported by the shift output shaft 45, and the idle gear 713 supported by the traveling transmission shaft 235 (see FIG. 27). ), The reverse gear row 710R including the reverse side driven gear 712R meshed with the reverse side drive gear 711R, and the advance from the speed change output shaft 45 to the traveling transmission shaft 235 via the forward gear row 710F. A forward clutch mechanism 720F that engages and disengages power transmission in the direction, and a reverse clutch mechanism 720R that engages and disengages power transmission in the reverse direction from the shift output shaft 45 to the traveling transmission shaft 235 via the reverse gear train 710R. And have.

As shown in FIG. 28, in the present embodiment, the forward drive gear 711F is unable to rotate relative to the rear portion of the speed change output shaft 45 extending rearward from the second bearing plate 554B. The reverse drive gear 711R is supported so as to be non-rotatably supported by a rear portion of the shift output shaft 45 at a position separated from the forward drive gear 711F in the axial direction.

In the present embodiment, the shift output shaft 45 is located on the rear side with the first shift output shaft 45a located on the front side, and is coaxially with the first shift output shaft 45a so that it cannot rotate relative to the axis. It has a second shift output shaft 45b to be connected, and the second shift output shaft 45b forms a rear portion of the shift output shaft 45.

The forward-side driven gear 712F is relatively rotatable at the same position as the forward-side drive gear 711F in the axial direction in the rear portion of the traveling transmission shaft 235 extending rearward from the second bearing plate 554B. Is supported by.
The reverse-side driven gear 712R is rotatably supported by a rear portion of the traveling transmission shaft 235 at the same position as the reverse-side drive gear 711R in the axial direction.

The forward side and reverse side clutch mechanisms 720F and 720R are supported by the rear portion of the traveling transmission shaft 235 while being positioned between the forward side driven gear 712F and the reverse side driven gear 712R in the axial direction. Has been done.

In the present embodiment, the traveling transmission shaft 235 is located on the front side of the first traveling transmission shaft 235a and on the rear side, and is coaxial with the first traveling transmission shaft 235a so that it cannot rotate relative to the axis. It has a second traveling transmission shaft 235b to be connected, and the second traveling transmission shaft 235b forms a rear portion of the traveling transmission shaft.

By providing such a housing structure, the transmission structure 9 according to the present embodiment can effectively reduce the number of gears used and reduce the size.

As described above, in the present embodiment, the output side third driven gear 774 (3) is positioned at the same position as the output side second driven gear 774 (2) in the axial direction, and the output side second 2 It is meshed with the driven gear 774 (2).

Instead of this, the output side third driven gear 774 (3) is positioned at the same position as the output side first driven gear 774 (1) in the axial direction, and the output side first driven gear 774 (1) is positioned. ), In this case, the output side third clutch mechanism 80 (3) is based on the output side first driven gear 774 (1) in the axial direction. And, in a state of being positioned on the side opposite to the second clutch mechanisms 80 (1) and 80 (2), the traveling transmission shaft 235 is supported by a portion of the traveling transmission shaft 235 located in the compartment S.

As shown in FIG. 28, in the present embodiment, the input side first and second clutch mechanisms 60 are attached to the bearing portions of the main drive shaft 212 in the main drive shaft 212 and the second bearing plate 554B. A rotary joint 68 for supplying and discharging hydraulic oil to (1) and 60 (2) is provided.

Further, hydraulic oil is supplied to the output side first and second clutch mechanisms 80 (1) and 80 (2) to the speed change output shaft and the bearing portion of the speed change output shaft in the first bearing plate 516B. A rotary joint 88 for discharging is provided.

Further, the transfer cylinder portion 555 mounted on the traveling transmission shaft and the second bearing plate has the output side third clutch mechanism 80 (3), the forward side clutch mechanism 720F, and the reverse side clutch mechanism 720R. A rotary joint 238 for supplying and discharging hydraulic oil is provided.

1-9 Transmission structure 10 HST
12 Pump shaft 16 Motor shaft 20 Output adjustment member 30 Planetary gear mechanism 32 Sun gear 36 Internal gear 38 Carrier 43 Shift intermediate shaft 44 Shift transmission shaft 45 Shift output shaft 50 (1), 750 (1) Input side first transmission mechanism 50 (2), 750 (2) Input side second transmission mechanism 52 (1), 752 (1) Input side first drive gear 52 (2), 752 (2) Input side second drive gear 54 (1), 754 (1) Input-side first driven gear 54 (2), 754 (2) Input-side second driven gear 60 (1) Input-side first clutch mechanism 60 (2) Input-side second clutch mechanism 70 (1), 770 (1) Output side first transmission mechanism (forward first transmission mechanism)
70 (2), 770 (2) Output side second transmission mechanism (forward second transmission mechanism)
70 (3), 770 (3) Output side third transmission mechanism 70 (R) Reverse transmission mechanism 72 (1) Output side first drive gear 72 (2) Output side second drive gear 72 (3) Output side third Drive gears 74 (1), 774 (1) Output side first driven gear 74 (2), 774 (2) Output side second driven gear 74 (3), 774 (3) Output side third driven gear 80 (1) ) Output side first clutch mechanism (forward first clutch mechanism)
80 (2) Output side second clutch mechanism (forward second clutch mechanism)
80 (3) Output side third clutch mechanism 80 (R) Reverse clutch mechanism 90 Speed change operation member 95a HST sensor 95b Output sensor 100 Control device 150 Hydraulic source 155 Pressure oil supply line 157 Drain line 160 (1) First supply / discharge line 160 (2) 2nd supply / discharge line 165 Switching valve 200 Work vehicle 210 Drive source 212 Main drive shaft 220 Drive wheel 230 Forward / backward switching mechanism 240 Sub-transmission mechanism 360 (1) Input side 1st supply / discharge line 360 (2) Input Side 2nd supply / discharge line 362 (1) Output side 1st supply / discharge line 362 (2) Output side 2nd supply / discharge line 365 (1) Input side 1st solenoid valve 365 (2) Input side 2nd solenoid valve 367 ( 1) Output side first solenoid valve 367 (2) Output side second solenoid valve 370 (1) Input side first pressure sensor 370 (2) Input side second pressure sensor 372 (1) Output side first pressure sensor 372 ( 2) Output side second pressure sensor 412 Input side slider 412 (1) First unevenness engaging part 412 (2) Second unevenness engaging part 432 Output side slider 505B Housing body 510, 510B Front housing body 511 Boss part 550, 550B Rear housing body 551 Boss 516, 516B 1st bearing plate 554, 554B 2nd bearing plate

Claims (31)

With HST, the rotational power that is operatively input from the drive source to the pump shaft is continuously changed to at least the rotational power between the 1st HST speed and the 2nd HST speed according to the operating position of the output adjusting member, and is output from the motor shaft. ,
A planetary gear mechanism having first to third elements and the third element acting as an input unit for HST output.
Shift output shaft and
An input-side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at the input-side first gear ratio,
An input-side second transmission mechanism capable of transmitting the rotational power of the drive source to the second element at an input-side second gear ratio,
An input side first clutch mechanism and an input side second clutch mechanism that engage and disengage the power transmission of the input side first transmission mechanism and the input side second transmission mechanism, respectively.
An output-side first transmission mechanism capable of transmitting the rotational power of the second element to the shift output shaft at the output-side first gear ratio,
An output-side second transmission mechanism capable of transmitting the rotational power of the first element to the shift output shaft at the output-side second gear ratio,
The output side first clutch mechanism and the output side second clutch mechanism that engage and disengage the power transmission of the output side first transmission mechanism and the output side second transmission mechanism, respectively.
Shift control member and
An HST sensor that directly or indirectly detects the HST shift state,
An output sensor that directly or indirectly detects the rotational speed of the speed change output shaft,
It includes the output adjusting member, the input side first and second clutch mechanisms, and a control device for controlling the operation of the output side first and second clutch mechanisms.
Based on the detection signals of the HST sensor and the output sensor, the control device engages the input side and the output side first clutch mechanisms in a low speed state in which the rotation speed of the speed change output shaft is less than a predetermined switching speed. By setting the input side and the output side second clutch mechanism to the disengaged state, the first element acts as an input unit of the reference power operatively transmitted from the drive source, and the second element is synthesized. The output adjusting member shifts the HST output from the first HST speed to the second HST speed in response to the speed-increasing operation of the speed change operating member while displaying the first transmission state that acts as the output unit of the rotational power. On the other hand, when the rotation speed of the speed change output shaft is higher than the switching speed, the input side and output side first clutch mechanisms are shut off and the input side and output side second clutch mechanisms are engaged. In the combined state, the first element acts as an output unit and the second element acts as an input unit of the reference power, and the second transmission state appears, and the speed increasing operation of the speed change operation member is performed. The output adjusting member is operated so that the HST output shifts from the second HST speed to the first HST speed.
The input-side first and second gear ratios are the rotation speed of the second element when the HST output is set to the second HST speed in the first transmission state and the input-side second transmission mechanism in the second transmission state. The rotation speed of the first element and the first transmission when the rotation speed of the second element due to the rotational power transmitted via the above is the same and the HST output is the second HST speed in the second transmission state. It is set so that the rotation speed of the first element due to the rotational power transmitted via the first transmission mechanism on the input side in the state is the same.
The output-side first and second gear ratios are set so that the rotation speeds appearing on the shift output shaft are the same in the first and second transmission states when the HST output is set to the second HST speed. The transmission structure is characterized by being With HST, the rotational power that is operatively input from the drive source to the pump shaft is continuously changed to at least the rotational power between the 1st HST speed and the 2nd HST speed according to the operating position of the output adjusting member, and is output from the motor shaft. ,
A planetary gear mechanism having first to third elements and the third element acting as an input unit for HST output.
Shift output shaft and
An input-side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at the input-side first gear ratio,
An input-side second transmission mechanism capable of transmitting the rotational power of the drive source to the second element at an input-side second gear ratio,
An input side first clutch mechanism and an input side second clutch mechanism that engage and disengage the power transmission of the input side first transmission mechanism and the input side second transmission mechanism, respectively.
The output side first and second clutch mechanisms that engage and disengage the power transmission from the second element and the first element to the speed change output shaft, respectively.
Shift control member and
An HST sensor that directly or indirectly detects the HST shift state,
An output sensor that directly or indirectly detects the rotational speed of the speed change output shaft,
It includes the output adjusting member, the input side first and second clutch mechanisms, and a control device for controlling the operation of the output side first and second clutch mechanisms.
Based on the detection signals of the HST sensor and the output sensor, the control device engages the input side and the output side first clutch mechanisms in a low speed state in which the rotation speed of the speed change output shaft is less than a predetermined switching speed. By setting the input side and the output side second clutch mechanism to the disengaged state, the first element acts as an input unit of the reference power operatively transmitted from the drive source, and the second element is synthesized. The output adjusting member shifts the HST output from the first HST speed to the second HST speed in response to the speed-increasing operation of the speed change operating member while displaying the first transmission state that acts as the output unit of the rotational power. On the other hand, when the rotation speed of the speed change output shaft is higher than the switching speed, the input side and output side first clutch mechanisms are shut off and the input side and output side second clutch mechanisms are engaged. In the combined state, the first element acts as an output unit and the second element acts as an input unit of the reference power, and the second transmission state appears, and the speed increasing operation of the speed change operation member is performed. The output adjusting member is operated so that the HST output shifts from the second HST speed to the first HST speed.
The input-side first and second gear ratios are the rotational speed of the second element when the HST output is set to the second HST speed in the first transmission state and the input-side second transmission mechanism in the second transmission state. The rotational speed of the first element and the first transmission when the rotational speed of the second element due to the rotational power transmitted via the above is the same and the HST output is the second HST speed in the second transmission state. The transmission structure is characterized in that the rotational speed of the first element due to the rotational power transmitted via the first transmission mechanism on the input side is set to be the same in the state. When switching between the first transmission state and the second transmission state, the control device displays the rotational speed displayed on the shift output shaft in the transmission state after switching on the shift output shaft in the transmission state before switching. The transmission structure according to claim 2, wherein the output adjusting member is operated so as to match or approach the output rotational speed. In the transitional period of switching between the first and second transmission states, both the first and second clutch mechanisms on the input side are in the engaged state, and both the first and second clutch mechanisms on the output side are in the engaged state. The transmission structure according to any one of claims 1 to 3, wherein the double transmission state is manifested. At least one of the input side clutch unit formed by the input side first and second clutch mechanisms and the output side clutch unit formed by the output side first and second clutch mechanisms is a dog clutch type.
The dog clutch type clutch unit is supported by a corresponding rotating shaft so as to be relatively non-rotatable and movable in the axial direction, and has sliders having first and second concave-convex engaging portions on one side and the other side in the axial direction, respectively.
When the slider is positioned at the first position on one side in the axial direction, the first concave-convex engaging portion corresponds to the second concave-convex engaging portion while being disengaged from the corresponding concave-convex engaging portion. By engaging with the concave-convex engaging portion, only the first clutch mechanism is engaged, and when it is positioned at the second position on the other side in the axial direction, the first concave-convex engaging portion becomes the corresponding concave-convex engaging portion. On the other hand, the first concavo-convex engaging portion is engaged with the corresponding concavo-convex engaging portion while being disengaged, so that only the second clutch mechanism is engaged, and the slider is in the axial direction. When positioned at an intermediate position between the first and second positions, both the first and second concave-convex engaging portions are engaged with the corresponding concave-convex engaging portions, so that the first and second concave-convex engaging portions are engaged. The transmission structure according to claim 4, wherein both of the clutch mechanisms are engaged with each other. The input-side first transmission mechanism is operably connected to the input-side first drive gear and the input-side first drive gear, which are rotatably supported by a main drive shaft operably connected to the drive source. One element has a first driven gear on the input side that cannot rotate relative to each other.
The input-side second transmission mechanism is operably connected to the input-side second drive gear that is rotatably supported by the main drive shaft and the input-side second drive gear, and is unable to rotate relative to the second element. Has a first driven gear on the input side
The input side clutch unit is a dog clutch type, and has an input side slider as the slider.
The input side slider is supported between the input side first and second drive gears so as to be non-rotatable and movable in the axial direction with respect to the main drive shaft, and when it is positioned at the first position, the second unevenness is formed. The first concave-convex engaging portion is engaged with the concave-convex engaging portion of the input-side first drive gear while the engaging portion is not engaged with the concave-convex engaging portion of the first input-side second drive gear. As a result, only the input-side first clutch mechanism is engaged, and when it is positioned at the second position, the first concavo-convex engaging portion is not engaged with the concavo-convex engaging portion of the input-side first drive gear. By engaging the second uneven engagement portion with the concave-convex engaging portion of the input side second drive gear while being engaged, only the input side second clutch mechanism is engaged and the intermediate position When it is located at, the first and second concave-convex engaging portions are engaged with the concave-convex engaging portions of the input-side first and second drive gears, respectively, thereby engaging both the first and second clutch mechanisms. The transmission structure according to claim 5, wherein the gears are brought into a geared state. The second element is provided with a speed change intermediate shaft connected to the second element so as not to rotate relative to the axis.
The first element is supported by the shift intermediate shaft so as to be relatively rotatable.
The output-side first transmission mechanism is operatively connected to the output-side first drive gear supported on the shift intermediate shaft so as not to rotate relative to the output-side first drive gear, and is rotatable relative to the shift output shaft. It has a supported output side first driven gear and
The output-side second transmission mechanism is operatively connected to the output-side second drive gear that is non-rotatably connected to the first element and the output-side second drive gear, and is rotatable relative to the speed change output shaft. It has a supported output side second driven gear and
The output-side first and second clutch mechanisms are provided on the speed change output shaft between the concave-convex engaging portion provided on the output-side first and second driven gears and the output-side first and second driven gears. It has an output side slider that is supported so as to be relatively non-rotatable and movable in the axial direction, and has first and second uneven engagement portions on one side and the other side in the axial direction, respectively.
When the output side slider is positioned at the first position on one side in the axial direction, the second concave-convex engaging portion is disengaged from the concave-convex engaging portion of the output-side second driven gear. 1 The concave-convex engaging portion is engaged with the concave-convex engaging portion of the output-side first driven gear so that only the output-side first clutch mechanism is engaged and is positioned at the second position on the other side in the axial direction. Then, the first concave-convex engaging portion is disengaged from the concave-convex engaging portion of the output-side first driven gear, and the second concave-convex engaging portion engages with the concave-convex engaging portion of the output-side second driven gear. When only the output side second clutch mechanism is engaged by being engaged with the portion and is positioned at an intermediate position between the first position and the second position in the axial direction, the first and second positions are engaged. The concave-convex engaging portion is engaged with the concave-convex engaging portion of the first and second drive gears on the output side, respectively, so that both the first and second clutch mechanisms on the output side are engaged. The transmission structure according to claim 1. At least one of the input side clutch unit formed by the input side first and second clutch mechanisms and the output side clutch unit formed by the output side first and second clutch mechanisms receives a hydraulic oil supply and engages in a clutch. It is a hydraulically actuated friction plate type that reveals the clutch state.
The transmission structure includes a pressure oil supply line that receives pressure oil from a hydraulic source, and first and second clutch mechanisms that supply and discharge pressure oil to the first and second clutch mechanisms of a hydraulically operated friction plate type clutch unit, respectively. The second supply / discharge line and the first and second solenoid valves inserted in the first and second supply / discharge lines, respectively, have the discharge position for draining the corresponding supply / discharge line and the corresponding supply / discharge line. The first and second solenoid valves that can take a supply position for fluid connection to the hydraulic oil supply line and the clutch engagement detecting means for detecting the engagement state of the first and second clutch mechanisms in the friction plate type clutch unit are Be prepared,
The control device positions the first solenoid valve at the supply position and the second solenoid valve at the discharge position when the rotation speed of the speed change output shaft is lower than the switching speed, and the first transmission state. Is displayed, and when the rotation speed of the speed change output shaft is higher than the switching speed, the first solenoid valve is positioned at the discharge position and the second solenoid valve is positioned at the supply position to perform the second transmission state. At the time of switching between the first and second transmission states, the solenoid valve that was located at the supply position at the time before switching is maintained at the supply position, and is positioned at the discharge position at the time before switching. The solenoid valve that had been used was moved from the discharge position to the supply position, and the clutch mechanism to which pressure oil was supplied via the solenoid valve that was moved from the discharge position to the supply position became engaged. The fourth aspect of claim 4, wherein the solenoid valve located at the supply position at the time before switching is moved from the supply position to the discharge position after a predetermined time has elapsed from the time of recognition based on the signal from the detection means. Transmission structure. The first and second solenoid valves receive the hydraulic pressure of the corresponding supply / discharge line as the pilot pressure, and engage the hydraulic pressure of the corresponding supply / discharge line in a state where the position signal from the control device to the supply position is input. The transmission structure according to claim 8, wherein the solenoid valve is a proportional solenoid valve configured to maintain hydraulic pressure. The first and second clutch mechanisms on the input side are of a hydraulically operated type friction plate type that receives pressure oil supply to bring out the clutch engaged state.
The transmission structure includes a pressure oil supply line that receives pressure oil from a hydraulic source, and input-side first and second supply and discharge that supply and discharge pressure oil to the input-side first and second clutch mechanisms, respectively. The line and the first and second supply / discharge lines on the input side are respectively inserted, and a discharge position for draining the corresponding supply / discharge line and a supply position for fluidly connecting the corresponding supply / discharge line to the pressure oil supply line are taken. The first and second solenoid valves on the input side to be obtained and the clutch engagement detecting means for detecting the engaged state of the first and second clutch mechanisms on the input side are provided.
The control device positions the input side first solenoid valve at the supply position and the input side second solenoid valve at the discharge position when the rotation speed of the transmission output shaft is lower than the switching speed. When the rotation speed of the transmission output shaft is higher than the switching speed, the first and second solenoid valves on the input side are positioned at the discharge position and the second solenoid valve on the input side is positioned at the supply position. When switching the transmission state, the solenoid valve that was located at the supply position before switching is maintained at the supply position, and the solenoid valve that was located at the discharge position before switching is moved from the discharge position to the supply position. At the time when it is recognized based on the signal from the clutch engagement detecting means that the clutch mechanism to which the pressure oil is supplied via the solenoid valve that has been moved and moved from the discharge position to the supply position is in a slip engagement state. The transmission structure according to any one of claims 1 to 3, wherein the solenoid valve located at the supply position at the time before switching is moved from the supply position to the discharge position. The first and second clutch mechanisms on the output side are of the hydraulically actuated type friction plate type that receives pressure oil supply to bring out the clutch engaged state.
The transmission structure includes a pressure oil supply line that receives pressure oil from a hydraulic source, and output side first and second supply and discharge that supply and discharge pressure oil to the output side first and second clutch mechanisms, respectively. The line and the first and second supply / discharge lines on the output side are respectively inserted, and a discharge position for draining the corresponding supply / discharge line and a supply position for fluidly connecting the corresponding supply / discharge line to the pressure oil supply line are taken. The first and second solenoid valves on the output side to be obtained and the clutch engagement detecting means for detecting the engagement state of the first and second clutch mechanisms on the output side are provided.
The control device positions the output side first solenoid valve at the supply position and the output side second solenoid valve at the discharge position when the rotation speed of the transmission output shaft is lower than the switching speed. When the rotation speed of the transmission output shaft is higher than the switching speed, the output side first solenoid valve is positioned at the discharge position and the output side second solenoid valve is positioned at the supply position, while the low speed state and the high speed state are set. At the time of switching, the solenoid valve that was located at the supply position at the time before switching is maintained at the supply position, and the solenoid valve that was located at the discharge position at the time before switching is moved from the discharge position to the supply position. Before switching, when it is recognized based on the signal from the clutch engagement detecting means that the clutch mechanism to which the pressure oil is supplied via the solenoid valve moved from the discharge position to the supply position is in a slip engagement state. The transmission structure according to any one of claims 1 to 3, wherein the solenoid valve located at the supply position at the time of is moved from the supply position to the discharge position. The transmission structure according to any one of claims 1 to 3, wherein the input side second clutch mechanism and the output side second clutch mechanism are friction plate type clutch mechanisms. The transmission structure according to claim 12, wherein the input-side first clutch mechanism and the output-side first clutch mechanism are friction plate type clutch mechanisms. A pressure oil supply line whose upstream side is fluidly connected to the hydraulic source,
With the drain line
A first supply / discharge line for supplying / discharging pressure oil to the input side and output side first clutch mechanisms,
A second supply / discharge line for supplying / discharging pressure oil to the input side and output side second clutch mechanisms,
A switching valve whose position is controlled by the control device is provided.
The switching valve connects the first position where the pressure oil supply / discharge line is fluidly connected to the first supply / discharge line and the second supply / discharge line is fluidly connected to the drain line, and the first supply / discharge line. It is configured to have a second position where the fluid is connected to the drain line and the pressure oil supply / discharge line is fluidly connected to the second supply / discharge line.
The input-side first and second clutch mechanisms and the output-side first and second clutch mechanisms are hydraulically actuated in that they receive pressure oil supply and engage the power transmission of the corresponding transmission mechanism. The transmission structure according to claim 12 or 13. It is a transmission structure that is inserted in the transmission path of the traveling system of the work vehicle.
With HST, the rotational power that is operatively input from the drive source to the pump shaft is continuously changed to at least the rotational power between the 1st HST speed and the 2nd HST speed according to the operating position of the output adjusting member, and is output from the motor shaft. ,
A planetary gear mechanism having first to third elements and the third element acting as an input unit for HST output.
Shift output shaft and
An input-side first transmission mechanism and an input-side second transmission mechanism capable of transmitting the rotational power of the drive source to the first and second elements, respectively.
An input side first clutch mechanism and an input side second clutch mechanism that engage and disengage the power transmission of the input side first transmission mechanism and the input side second transmission mechanism, respectively.
The output side first and second clutch mechanisms that engage and disengage the power transmission from the second element and the first element to the speed change output shaft, respectively.
Shift control member and
An HST sensor that directly or indirectly detects the HST shift state,
An output sensor that directly or indirectly detects the rotational speed of the speed change output shaft,
It includes the output adjusting member, the input side first and second clutch mechanisms, and a control device for controlling the operation of the output side first and second clutch mechanisms.
At least one of the input side clutch unit formed by the input side first and second clutch mechanisms and the output side clutch unit formed by the output side first and second clutch mechanisms receives a hydraulic oil supply and engages in a clutch. It is a hydraulically actuated friction plate type that reveals the clutch state.
The transmission structure further includes a pressure oil supply line that receives pressure oil from a hydraulic source.
The first and second supply / discharge lines for supplying / discharging pressure oil to the first and second clutch mechanisms in the hydraulically operated friction plate type clutch unit, respectively.
The first and second solenoid valves inserted in the first and second supply / discharge lines, respectively, have a discharge position for draining the corresponding supply / discharge line and the corresponding supply / discharge line as a fluid in the pressure oil supply line. The first and second solenoid valves that can take the supply position to be connected,
It is provided with a clutch engagement detecting means for detecting the engaged state of the first and second clutch mechanisms in the hydraulically operated friction plate type clutch unit.
Based on the detection signals of the HST sensor and the output sensor, the control device engages the input side and the output side first clutch mechanisms in a low speed state in which the rotation speed of the speed change output shaft is less than a predetermined switching speed. By setting the second clutch mechanism on the input side and the second clutch mechanism on the output side to the disengaged state, the first element acts as an input unit for reference power operatively transmitted from the drive source, and the second element is combined and rotated. The output adjusting member is moved so that the HST output shifts from the first HST speed to the second HST speed in response to the speed increasing operation of the speed change operation member while displaying the first transmission state that acts as the power output unit. On the other hand, when the rotation speed of the speed change output shaft is higher than the switching speed, the input side and the output side first clutch mechanism are disconnected and the input side and the output side second clutch mechanism are engaged. By setting the state, the second transmission state in which the first element acts as an output unit and the second element acts as an input unit of the reference power is exhibited, and in response to the speed increasing operation of the speed change operation member. The output adjusting member is operated so that the HST output shifts from the second HST speed to the first HST speed, and when the first and second transmission states are switched, the HST output is positioned at the supply position before the switching. While maintaining one of the first and second electromagnetic valves in the supply position, the other of the first and second electromagnetic valves, which was located in the discharge position at the time before switching, is moved from the discharge position to the supply position. When it is recognized based on the signal from the clutch engagement detecting means that the clutch mechanism supplied with pressure oil via the other electromagnetic valve is in a sliding engagement state, the one electromagnetic valve is supplied. A transmission structure characterized in that the engagement / disengagement of the first and second clutch mechanisms in the friction plate type clutch unit is switched by moving from the position to the discharge position. With HST, the rotational power that is operatively input from the drive source to the pump shaft is continuously changed to at least the rotational power between the 1st HST speed and the 2nd HST speed according to the operating position of the output adjusting member, and is output from the motor shaft. ,
A planetary gear mechanism having first to third elements and the third element acting as an input unit for HST output.
Shift output shaft and
Input-side first and second transmission mechanisms capable of transmitting the rotational power of the drive source to the first element and the second element, respectively.
Input-side first and second clutch mechanisms that engage and disengage the power transmission of the input-side first and second transmission mechanisms, respectively.
A forward first transmission mechanism and a forward second transmission mechanism capable of transmitting the rotational power of the second element and the first element to the shift output shaft in a normal rotation state, respectively.
A reverse transmission mechanism capable of transmitting the rotational power of the second element to the shift output shaft in a reverse state,
The forward first clutch mechanism, the forward second clutch mechanism, and the reverse clutch mechanism that engage and disengage the power transmissions of the forward first transmission mechanism, the forward second transmission mechanism, and the reverse transmission mechanism, respectively.
Shift control member and
An HST sensor that directly or indirectly detects the HST shift state,
An output sensor that directly or indirectly detects the rotational speed of the speed change output shaft,
The output adjusting member, the input side first clutch mechanism, the input side second clutch mechanism, the forward first clutch mechanism, the forward second clutch mechanism, and a control device for controlling the operation of the reverse clutch mechanism are provided.
Based on the detection signals of the HST sensor and the output sensor, the control device has the input side first clutch mechanism and the input side first clutch mechanism in a low speed state in which the rotation speed of the shift output shaft is from zero speed to less than the switching speed in the forward direction. The HST output shifts from the first HST speed to the second HST speed in response to the forward speed increasing operation of the speed change operating member while displaying the forward first transmission state in which the forward first clutch mechanism is engaged. In a high-speed state in which the rotation speed of the speed change output shaft is equal to or higher than the switching speed in the forward direction, the input side second clutch mechanism and the forward second clutch mechanism are engaged with each other. The output adjusting member is operated so that the HST output shifts from the first HST speed to the second HST speed in response to the forward speed increasing operation of the speed change operating member while displaying the forward second transmission state. In the reverse transmission state in which the rotation speed of the speed change output shaft changes from zero speed to the reverse side, the reverse transmission state in which the first clutch mechanism on the input side and the reverse clutch mechanism are engaged is exhibited, and the said The transmission structure is characterized in that the output adjusting member is operated so that the HST output shifts from the first HST speed to the second HST speed in response to the reverse speed increasing operation of the speed change operating member. The input-side first transmission mechanism operates and transmits the rotational power of the drive source to the first element at the input-side first gear ratio, and the input-side second transmission mechanism transmits the rotational power of the drive source to the input-side second gear. The operation is transmitted to the second element at the gear ratio,
The input-side first and second gear ratios are the rotational speed of the second element when the HST output is set to the second HST speed in the forward first transmission state and the input-side second gear ratio in the forward second transmission state. The rotational speed of the second element due to the rotational power transmitted via the transmission mechanism is the same as the rotational speed of the first element when the HST output is set to the second HST speed in the forward second transmission state. 16. The claim 16 is characterized in that the rotational speed of the first element due to the rotational power transmitted via the input-side first transmission mechanism in the forward first transmission state is set to be the same. The transmission structure described in. The forward first transmission mechanism operates and transmits the rotational power of the second element to the shift output shaft at the forward first gear ratio, and the forward second transmission mechanism transmits the forward second element male rotational power to the forward second gear. The operation is transmitted to the shift output shaft at the gear ratio,
The forward first and second gear ratios are set so that the rotation speeds appearing on the shift output shaft are the same in the first and second transmission states when the HST output is set to the second HST speed. The transmission structure according to claim 16 or 17, wherein the transmission structure is provided. The HST and the planetary gear mechanism are set so that the rotation speed of the second element becomes zero when the HST output is set to the first HST speed in the engaged state of the first clutch mechanism on the input side. The transmission structure according to any one of claims 16 to 18, wherein the transmission structure is provided. With HST, the rotational power that is operatively input from the drive source to the pump shaft is continuously changed to at least the rotational power between the 1st HST speed and the 2nd HST speed according to the operating position of the output adjusting member, and is output from the motor shaft. ,
A planetary gear mechanism having first to third elements and the third element acting as an input unit for HST output.
Shift output shaft and
An input-side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at the input-side first gear ratio,
An input-side second transmission mechanism capable of transmitting the rotational power of the drive source to the second element at an input-side second gear ratio,
An input side first clutch mechanism and an input side second clutch mechanism that engage and disengage the power transmission of the input side first transmission mechanism and the input side second transmission mechanism, respectively.
An output-side first transmission mechanism capable of transmitting the rotational power of the second element to the shift output shaft at the output-side first gear ratio,
An output-side second transmission mechanism capable of transmitting the rotational power of the first element to the shift output shaft at the output-side second gear ratio,
An output-side third transmission mechanism capable of transmitting the rotational power of the first element to the shift output shaft at an output-side third gear ratio that rotates the shift output shaft at a higher speed than the output-side second gear ratio.
The output side first to third clutch mechanisms that engage and disengage the power transmission of the output side first to third transmission mechanisms, respectively.
Shift control member and
An HST sensor that directly or indirectly detects the HST shift state,
An output sensor that directly or indirectly detects the rotational speed of the speed change output shaft,
It includes the output adjusting member, the input side first and second clutch mechanisms, and a control device for controlling the operation of the output side first to third clutch mechanisms.
Based on the detection signals of the HST sensor and the output sensor, the control device engages the input side first clutch mechanism in a low speed state in which the rotation speed of the speed change output shaft is less than the first switching speed. By disengaging the second clutch mechanism on the input side, engaging the first clutch mechanism on the first output side, and disengaging the other clutch mechanism on the output side, the first element can be disengaged from the drive source. In response to the speed-increasing operation of the speed change operating member, while revealing the first transmission state in which the second element acts as an input unit of the reference power to be operatively transmitted and acts as an output unit of the combined rotational power. In an intermediate speed state in which the output adjusting member is operated so that the HST output shifts from the first HST speed to the second HST speed and the rotation speed of the shift output shaft is equal to or higher than the first switching speed and lower than the second switching speed. The input side first clutch mechanism is in the disengaged state and the input side second clutch mechanism is in the engaged state, the output side second clutch mechanism is in the engaged state, and the other output side clutch mechanism is in the disengaged state. By doing so, the second transmission state in which the second element acts as an input unit for the reference power and the rotational power of the first element is transmitted to the shift output shaft at the output side second gear ratio is displayed. The output adjusting member is operated so that the HST output shifts from the second HST speed to the first HST speed in response to the speed increasing operation of the shifting operation member, and the rotation speed of the shifting output shaft is equal to or higher than the second switching speed. In the high-speed state, the first clutch mechanism on the input side is engaged and the second clutch mechanism on the input side is engaged, while the third clutch mechanism on the output side is engaged and another clutch on the output side. By setting the mechanism in the cutoff state, the second element acts as an input unit for the reference power, and the rotational power of the first element is operated and transmitted to the shift output shaft at the output side third gear ratio. While operating the output adjusting member so that the HST output shifts from the side of the second HST speed to the side of the first HST speed in response to the speed increasing operation of the speed change operating member, the second And when switching between the third transmission states, the rotation speed appearing on the shift output shaft in the transmission state after switching matches or approaches the rotation speed appearing on the shift output shaft in the transmission state before switching. As described above, the output adjusting member is operated.
The input-side first and second gear ratios are the rotational speed of the second element when the HST output is set to the second HST speed in the first transmission state and the input-side second transmission mechanism in the second transmission state. The rotational speed of the first element and the first transmission when the rotational speed of the second element due to the rotational power transmitted via the above is the same and the HST output is the second HST speed in the second transmission state. The transmission structure is characterized in that the rotational speed of the first element due to the rotational power transmitted via the first transmission mechanism on the input side is set to be the same in the state. A transmission intermediate shaft connected to the second element so as not to rotate relative to the axis,
It is provided with a speed change transmission shaft that is extrapolated to the speed change intermediate shaft so as to be relatively rotatable and is connected to the first element so as to be relatively non-rotatable.
The input-side first transmission mechanism is operably connected to the input-side first drive gear supported by a main drive shaft operably connected to the drive source and is rotatably supported by the input-side first drive gear, and is said to shift gears. The transmission shaft has a first driven gear on the input side that cannot rotate relative to each other.
The input-side second transmission mechanism is operably connected to the input-side second drive gear that is rotatably supported by the main drive shaft and the input-side second drive gear, and is unable to rotate relative to the second element. Has a second driven gear on the input side
The output-side first transmission mechanism is operably connected to the output-side first drive gear supported on the shift intermediate shaft so as not to rotate relative to the shift output shaft, and is rotatable relative to the shift output shaft. It has a supported output side first driven gear and
The output-side second transmission mechanism is operably connected to the output-side second drive gear supported on the shift transmission shaft so as to be non-rotatable, and is operably connected to the output-side second drive gear and is rotatable relative to the shift output shaft. It has a supported output side second driven gear and
The output-side third transmission mechanism is operably connected to the output-side third drive gear supported on the shift transmission shaft so as not to rotate relative to the shift transmission shaft, and is operably connected to the output-side third drive gear and is rotatable relative to the shift output shaft. The transmission structure according to claim 20, further comprising a supported output-side third driven gear. Forward / backward switching that allows the rotation direction of the driving force to be switched between the shift output shaft and the travel transmission shaft, which is arranged on the downstream side of the transmission direction from the shift output shaft, in the forward direction and the reverse direction. The transmission structure according to any one of claims 1 to 21, further comprising a mechanism. With HST, the rotational power that is operatively input from the drive source to the pump shaft is continuously changed to at least the rotational power between the 1st HST speed and the 2nd HST speed according to the operating position of the output adjusting member, and is output from the motor shaft. ,
A planetary gear mechanism having first to third elements and the third element acting as an input unit for HST output.
An input-side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at the input-side first gear ratio,
An input-side second transmission mechanism capable of transmitting the rotational power of the drive source to the second element at an input-side second gear ratio,
An input side first clutch mechanism and an input side second clutch mechanism that engage and disengage the power transmission of the input side first transmission mechanism and the input side second transmission mechanism, respectively.
Shift output shaft and
A traveling transmission shaft arranged on the downstream side in the transmission direction from the shift output shaft,
Forward and backward movement that is inserted in the transmission path from the shift output shaft to the traveling transmission shaft and can be switched between a forward transmission state that rotates the traveling transmission shaft in the forward direction and a reverse transmission state that rotates the traveling transmission shaft in the reverse direction. Switching mechanism and
An output-side first transmission mechanism capable of transmitting the rotational power of the second element to the shift output shaft at the output-side first gear ratio,
An output-side second transmission mechanism capable of transmitting the rotational power of the first element to the shift output shaft at the output-side second gear ratio,
An output-side third transmission mechanism capable of transmitting the rotational power of the first element to the traveling transmission shaft as a driving force in the forward direction, the output-side second transmission mechanism and the forward / backward switching mechanism in the forward transmission state. The rotational power of the first element is higher than the rotational speed of the traveling transmission shaft when the rotational power of the first element is operating and transmitted to the traveling transmission shaft via the output side third transmission mechanism. An output-side third transmission mechanism whose gear ratio is set so that the rotation speed of the traveling transmission shaft when the operation is transmitted to the traveling transmission shaft becomes high.
The output side first to third clutch mechanisms that engage and disengage the power transmission of the output side first to third transmission mechanisms, respectively.
Shift control member and
An HST sensor that directly or indirectly detects the HST shift state,
It includes the output adjusting member, the input side first and second clutch mechanisms, and a control device for controlling the operation of the output side first to third clutch mechanisms.
The control device is
In response to the operation of the speed change operating member to the zero speed position, the output adjusting member is operated so that the HST output becomes the first HST speed that makes the combined rotational power zero.
When the speed change operating member is operated in the forward side low speed range from the zero speed position to the forward side first switching speed position, the input side first clutch mechanism is engaged and the input side first clutch mechanism is engaged. By disengaging the two clutch mechanisms, engaging the first output-side first clutch mechanism, and disengaging the other output-side clutch mechanisms, the first element is operatively transmitted from the drive source. While revealing the first transmission state in which the second element acts as an input unit of the reference power to be operated and the second element acts as an output unit of the combined rotational power, the forward / backward switching mechanism is set to the forward transmission state, and the above-mentioned The output adjusting member is operated so that the HST output shifts from the side of the first HST speed to the side of the second HST speed according to the speed increasing operation of the speed change operating member.
When the speed change operating member is operated in the forward side intermediate speed range between the forward side first switching speed position and the forward side second switching speed position, the input side first clutch mechanism is shut off. By engaging the second clutch mechanism on the input side, engaging the second clutch mechanism on the output side, and disengaging the other clutch mechanism on the output side, the second element is input to the reference power. While exhibiting a second transmission state in which the rotational power of the first element is transmitted to the shift output shaft at the output side second gear ratio, the forward / backward switching mechanism is brought into the forward transmission state. In addition, the output adjusting member is operated so that the HST output shifts from the side of the second HST speed to the side of the first HST speed in response to the speed increasing operation of the speed change operating member.
When the speed change operating member is operated in the forward side high speed range exceeding the forward side second switching speed position, the input side first clutch mechanism is in the cutoff state and the input side second clutch mechanism is in the engaged state. By engaging the output-side third clutch mechanism and disengaging the other output-side clutch mechanisms, the second element acts as an input unit for reference power and the first element rotates. The HST output is generated in response to the speed-increasing operation of the speed change operating member while displaying the third transmission state in which the power is transmitted to the traveling transmission shaft as the driving force in the forward direction via the output side third transmission mechanism. The output adjusting member is operated so as to shift from the side of the second HST speed to the side of the first HST speed.
When the speed change operating member passes through the forward side second switching speed position between the forward side medium speed range and the forward side high speed range, the rotation of the traveling transmission shaft in the transmission state that appears immediately after the passage. The output adjusting member is operated so that the speed matches or approaches the rotational speed of the traveling output shaft in the transmission state that appears immediately before passing.
When the speed change operating member is operated in the reverse low speed range from the zero speed position to the reverse first switching speed position, the forward / backward switching mechanism is displayed while displaying the first transmission state. The output adjusting member is operated so as to be in the reverse transmission state and the HST output is changed from the side of the first HST speed to the side of the second HST speed in response to the speed increasing operation of the speed change operating member.
When the speed change operation member is operated in the reverse speed range exceeding the reverse reverse first switching speed position, the forward / backward switching mechanism is brought into the reverse transmission state while displaying the second transmission state. Further, the output adjusting member is operated so that the HST output shifts from the side of the second HST speed to the side of the first HST speed in response to the speed increasing operation of the speed change operating member.
The input-side first and second gear ratios are the rotational speed of the second element when the HST output is set to the second HST speed in the first transmission state and the input-side second transmission mechanism in the second transmission state. The rotational speed of the first element and the first transmission when the rotational speed of the second element due to the rotational power transmitted via the above is the same and the HST output is the second HST speed in the second transmission state. The transmission structure is characterized in that the rotational speed of the first element due to the rotational power transmitted via the first transmission mechanism on the input side is set to be the same in the state. The second element is provided with a speed change intermediate shaft connected to the second element so as not to rotate relative to the axis.
The input-side first transmission mechanism is supported by the input-side first drive gear that is rotatably supported by the main drive shaft that is operatively connected to the drive source, and by the transmission intermediate shaft that is rotatably supported. , The input side first drive gear and the input side first driven gear operatively connected to the first element.
The input-side second transmission mechanism includes an input-side second drive gear that is supported by the main drive shaft so as to be relatively rotatable, and the input-side second drive gear that is supported by the speed change intermediate shaft so that it cannot rotate relative to the main drive shaft. Has an input side second driven gear that is actuated and connected to
The output-side first transmission mechanism has an output-side first driven gear that is operably connected to the input-side second driven gear in a state of being supported by the speed change output shaft so as to be relatively rotatable.
The output-side second transmission mechanism has an output-side second driven gear that is operably connected to the input-side first driven gear in a state of being relatively rotatable and supported by the speed change output shaft.
The output-side third transmission mechanism has an output-side third driven gear that is operably connected to one of the output-side first and second driven gears while being supported by the traveling transmission shaft so as to be relatively rotatable.
The input-side first and second clutch mechanisms are supported by the main drive shaft so as to engage and disengage the input-side first and second drive gears with the main drive shaft, respectively.
The output-side first and second clutch mechanisms are supported by the shift output shaft so as to engage and disengage the output-side first and second driven gears with the shift output shaft, respectively.
23. The transmission structure according to claim 23, wherein the output-side third clutch mechanism is supported by the traveling transmission shaft so as to engage and disengage the output-side third driven gear with the traveling transmission shaft. Hollow housing body and
A first bearing plate detachably connected to the housing body and
A second bearing plate detachably connected to the housing body at a position separated from the first bearing plate in the longitudinal direction of the housing body is provided.
The main drive shaft, the shift intermediate shaft, the shift output shaft, and the traveling transmission shaft are supported by the first and second bearing plates in a state parallel to each other.
The input side first and second drive gears and the input side first and second clutch mechanisms are placed between the input side first and second drive gears in the axial direction of the main drive shaft. With the second clutch mechanism positioned, it is supported by a portion of the main drive shaft located in the compartmentalized space sandwiched between the first and second bearing plates.
The input-side first and second driven gears are located in the compartment space of the shift intermediate shaft in a state where they are positioned at the same positions as the input-side first and second drive gears in the axial direction, respectively. Supported by the part,
In the output side first and second driven gears and the output side first and second clutch mechanisms, the output side first and second driven gears have the input side second and first driven gears in the axial direction, respectively. In the section space of the speed change output shaft, with the output side first and second clutch mechanisms positioned between the input side first and second driven gears in the axial direction. Supported by the part located in
In the output-side third driven gear and the output-side third clutch mechanism, the output-side third driven gear is positioned at the same axial position as one of the output-side first and second driven gears, and the output-side first. 3 Of the traveling transmission shafts, with the clutch mechanism positioned on the side opposite to the output side 1st and 2nd clutch mechanisms with respect to one of the output side 1st and 2nd driven gears in the axial direction. Supported by a portion located in the compartment,
The transmission structure according to claim 24, wherein the forward / backward switching mechanism is supported by a portion of the shift output shaft and the traveling transmission shaft located outside the compartmentalized space. The housing body has a front housing body and a rear housing body that are detachably connected in series.
The first bearing plate is detachably connected to a boss portion provided on the inner surface of the front housing body in the vicinity of the rear opening of the front housing body.
The transmission structure according to claim 25, wherein the second bearing plate is detachably connected to a boss portion provided on the inner surface of the rear housing body in the vicinity of the front opening of the rear housing body. .. The output-side first and second gear ratios are set so that the rotation speeds appearing on the shift output shaft are the same in the first and second transmission states when the HST output is set to the second HST speed. The transmission structure according to any one of claims 20 to 26. When switching between the first transmission state and the second transmission state, the control device displays the rotational speed displayed on the shift output shaft in the transmission state after switching on the shift output shaft in the transmission state before switching. The transmission structure according to any one of claims 20 to 26, wherein the output adjusting member is operated so as to match or approach the output rotation speed. When the rotation direction of the rotational power input to the pump shaft is the forward rotation direction, the HST outputs the rotational power on one side in the forward and reverse directions as the HST output of the first HST speed and the HST output of the second HST speed. The transmission structure according to any one of claims 1 to 28, wherein the rotational power on the other side in the forward and reverse directions is output. The transmission structure according to any one of claims 1 to 29, wherein the internal gear, the carrier, and the sun gear of the planetary gear mechanism form the first, second, and third elements, respectively. With the drive source
With the drive wheels
The transmission structure according to any one of claims 1 to 30, which is inserted in a traveling system transmission path from the drive source to the drive wheels.
A work vehicle characterized in that the switching speed of the shift output shaft is set to be higher than the work speed range.

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