JP7300713B2 - Transmission structure and work vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transmission structure including a hydrostatic continuously variable transmission (HST) and a hydrostatic mechanical continuously variable transmission structure (HMT structure) having a planetary gear mechanism, and a working vehicle provided with the transmission structure.

The HMT structure, which is a combination of an HST and a planetary gear mechanism, is suitably used, for example, in the traveling system transmission path of work vehicles such as combine harvesters and tractors. Various configurations have been proposed for this purpose.

For example, in Patent Document 1 below, an HMT structure and a multi-speed transmission structure having three speed stages, low speed, middle speed and high speed, are arranged in series in a driving system transmission path to expand the vehicle speed variable range. A combine is disclosed.
However, the configuration described in Patent Document 1 is intended to perform the gearshift operation of the multistage gearshift structure in advance before the vehicle starts running, and the gearshift operation of the multistage gearshift structure is performed while the vehicle is running. and the following inconvenience occurs.

Regarding this point, the HMT structure is operated to increase the running vehicle speed while the multi-stage transmission structure is engaged with the low speed stage. A case of shifting to the middle speed will be described as an example.

In this case, when the output of the HMT structure reaches the maximum speed or near the maximum speed while the multi-speed gear structure is engaged in the low-speed stage, the output of the HMT structure is maintained at the maximum speed or near the maximum speed. When the multi-speed transmission structure is shifted from the low speed stage to the middle speed stage, a large change in vehicle speed occurs at the time of shifting, and the ride comfort is deteriorated, and an excessive load is applied to the traveling system transmission path.

Regarding this point, Patent Document 2 below discloses 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 transmission of the multi-speed transmission structure is performed while the vehicle is running. There has been proposed a work vehicle transmission capable of suppressing changes in vehicle speed and preventing an excessive load from being applied to a traveling system transmission path.

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 that multi-speeds the output of the HMT structure, and a lockup mechanism.

The HST has a pump that inputs rotational power from a drive source, a motor that is fluidly driven by the pump, and an output adjustment member that changes the volume of at least one of the pump and the motor (for example, the pump). The output adjusting member operates according to the amount of operation of the speed change operation member that is manually operated, and the rotational speed of the motor is continuously changed accordingly.

The planetary gear mechanism combines the rotational power from the HST input to the sun gear and the rotational power from the drive source input to the carrier, and outputs the result from the internal gear to the multi-speed transmission structure. It is
The lockup mechanism is configured to synchronously rotate the carrier and the internal gear only during a shift period of the multi-speed shift structure.

The shift operation of the transmission described in Patent Document 2 will be described by taking as an example the case where the multi-stage shift structure is increased from the first gear to the second gear.

When the speed change operation member is operated in the speed increasing direction within the first gear operation range, the output adjustment member changes the HST output from the first HST speed (for example, maximum speed on the reverse rotation side) to the second HST speed (for example, forward rotation). side maximum speed).

Then, when the shift operation member is operated to the boundary position between the first gear operation range and the second gear operation range, the output adjustment member is moved to the second HST speed position (for example, the maximum tilt position on the forward rotation side). ), and 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 gear engagement state of the multi-speed transmission structure.

When the shift operation member is operated into the second speed operation range beyond the boundary position between the first speed operation range and the second speed operation range, the multi-speed shift structure shifts to the first speed. The gear is accelerated from the gear to the second gear.

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

On the other hand, during the shift period of the multi-speed shift structure, the output adjustment 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, which are operatively connected to each other, are bounded by the rotational speeds of the internal gear and the carrier, which are connected by the locking mechanism and synchronously rotated by the rotational power from the drive source. is rotated at a rotational speed (hereinafter referred to as a speed change period rotational speed).

As a result, the output adjusting member is moved from the second HST speed position (for example, maximum tilt position on the forward rotation side) to a position (hereinafter referred to as a shift period reference position) at which an HST output corresponding to the rotation speed during the shift period of the sun gear appears. ) in the direction of the first HST speed position.

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

As described above, in the transmission described in Patent Document 2, during the shift operation of the multi-speed shift structure, the rotational power input to the sun gear is changed from the second HST speed (for example, the maximum speed on the forward rotation side) to 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 it is possible to suppress the range of change in the running vehicle speed during shifting of the multi-speed transmission structure, compared to the configuration described in Patent Document 1. However, there still remains a large speed change to some extent in the running vehicle speed at the time of shifting in the multi-speed transmission structure.

Japanese Patent No. 5822761 Japanese Patent No. 4162328

The present invention has been made in view of the above-described prior art, and provides a transmission structure having an HST, a planetary gear mechanism, and a speed change output shaft operatively driven by an output portion of the planetary gear mechanism, wherein the speed change output SUMMARY OF THE INVENTION It is an object of the present invention to provide a transmission structure capable of increasing the speed change width of the speed change output shaft without causing a sudden change in 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-mentioned object, a first aspect of the present invention provides rotational power that is operationally input from a drive source to a pump shaft at least from a first HST speed to a second HST speed according to the operating position of an output adjusting member. a planetary gear mechanism having first to third elements, the third element acting as an input portion of the HST output; and a speed change output shaft. an input-side first transmission mechanism capable of transmitting the operation of the rotational power of the drive source to the first element at the input-side first speed ratio; a second input-side transmission mechanism capable of transmitting an operation to an element; and a first input-side clutch mechanism and a second input-side clutch mechanism for engaging and disengaging power transmission of the first input-side transmission mechanism and the second input-side transmission mechanism, respectively. an output-side first transmission mechanism capable of transmitting the rotational power of the second element to the speed change output shaft at the output-side first speed ratio; and the rotational power of the first element at the output-side second speed ratio. a second output-side transmission mechanism capable of transmitting operation to a shift output shaft; a first output-side clutch mechanism and a second output-side clutch mechanism for engaging and disengaging power transmission of the first output-side transmission mechanism and the second output-side transmission mechanism, respectively; a clutch mechanism, a shift operating 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, the output adjustment member, A control device that controls the operation of the input side first and second clutch mechanisms and the output side first and second clutch mechanisms, and the control device responds to detection signals of the HST sensor and the output sensor. Therefore, when the rotational speed of the speed change output shaft is less than the predetermined switching speed, the input side and output side first clutch mechanisms are engaged and the input side and output side second clutch mechanisms are disengaged. As a result, a first transmission state is produced in which the first element acts as an input portion of the reference power operatively transmitted from the drive source and the second element acts as an output portion of the combined rotational power. While the output adjustment member is actuated so that the HST output shifts from the first HST speed to the second HST speed in accordance with the speed increasing operation of the speed change operation member, the rotational speed of the speed change output shaft changes to the switching speed. In the above-described high-speed state, the first element on the input side and the first output side is brought into the disengaged state and the second clutch mechanism on the input side and the output side is brought into the engaged state, thereby causing the first element to act as an output section. Further, the HST output shifts from the second HST speed to the first HST speed in accordance with the speed increasing operation of the speed change operation member while the second transmission state in which the second element acts as the input portion of the reference power is produced. and the input side first and second gear ratios are determined by the rotation speed of the second element and the second transmission state when the HST output is set to the second HST speed in the first transmission state. When the rotational speed of the second element due to the rotational power transmitted through the input side second transmission mechanism becomes the same, and the HST output is set to the second HST speed in the second transmission state, the 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, and The first and second gear ratios on the output side are set so that when the HST output is set to the second HST speed, the rotation speed appearing on the speed change output shaft is the same in the first and second transmission states. to provide a transmission structure that

Further, in order to achieve the first object, the second aspect of the present invention provides a rotary power that is operatively input from a drive source to a pump shaft in accordance with the operating position of an output adjusting member. a planetary gear mechanism having an HST that outputs rotational power from a motor shaft by steplessly changing rotational power between two HST speeds, first to third elements, the third element acting as an input portion of the HST output; an output shaft; an input-side first transmission mechanism capable of transmitting operation of the rotational power of the drive source to the first element at an input-side first speed ratio; a second input-side transmission mechanism capable of transmitting operation to a second element; and a first input-side clutch mechanism and a second input-side clutch mechanism for engaging and disengaging power transmission of the first input-side transmission mechanism and the second input-side transmission mechanism, respectively. a clutch mechanism, output-side first and second clutch mechanisms for respectively engaging and disengaging power transmission from the second element and the first element to the shift output shaft, a shift operation member, and a shift state of the HST directly. Alternatively, an HST sensor that indirectly detects, an output sensor that directly or indirectly detects the rotation speed of the speed change output shaft, the output adjustment member, the input side first and second clutch mechanisms, and the output side and a control device for controlling the operation of the first and second clutch mechanisms, wherein the control device reduces the rotation speed of the shift output shaft below a predetermined switching speed based on detection signals from the HST sensor and the output sensor. In a low-speed state, the first element on the input side and the output side is engaged and the second clutch mechanism on the input side and output side is disengaged so that the first element is operatively driven from the drive source. While creating the first transmission state in which the second element acts as the input portion of the transmitted reference power and the second element acts as the output portion of the combined rotational power, the HST output is generated in response to the speed increasing operation of the speed change operation member. While operating the output adjusting member so as to shift from the first HST speed to the second HST speed, in a high speed state where the rotation speed of the shift output shaft is equal to or higher than the switching speed, the input side and output side first clutches By disengaging the mechanism and engaging the input-side and output-side second clutch mechanisms, the first element acts as an output part and the second element acts as an input part for the reference power. The output adjustment member is operated so that the HST output shifts from the second HST speed toward the first HST speed in accordance with the speed increasing operation of the speed change operation member while the transmission state is exhibited. The second gear ratio is transmitted via the input-side second transmission mechanism in the second transmission state and the rotational speed of the second element when the HST output is set to the second HST speed in the first transmission state. The rotational speed of the first element when the rotational speed of the second element due to rotational power becomes the same and the HST output is set to the second HST speed in the second transmission state and the input in the first transmission state. Provided is a transmission structure that is set so that the rotation speed of the first element due to the rotation power transmitted via the side first transmission mechanism is the same.

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

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

In one form that produces the dual transmission state, an input side clutch unit formed by the input side first and second clutch mechanisms and an 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 rotary shaft so as to be non-rotatable relative to each other and movable in the axial direction, and has a slider having first and second concave-convex engaging portions on one side and the other side in the axial direction, respectively. be done.

When the slider is positioned at the first position on one side in the axial direction, the second uneven engagement portion is disengaged from the corresponding uneven engagement portion, and the first uneven engagement portion corresponds to the corresponding uneven engagement portion. Only the first clutch mechanism is brought into the engaged state by being engaged with the concave-convex engaging portion, and when the first clutch mechanism is positioned at the second position on the other side in the axial direction, the first concave-convex engaging portion engages the corresponding concave-convex engaging portion. On the other hand, only the second clutch mechanism is engaged by engaging the first uneven engagement portion with the corresponding uneven engagement portion while being disengaged, and the slider moves 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, whereby the first and second It is configured to engage both of the clutch mechanisms.

The first input-side transmission mechanism is operatively connected to a first input-side drive gear supported relatively rotatably on a main drive shaft operatively connected to the drive source, and operatively connected to the first input-side drive gear. The input-side second transmission mechanism includes an input-side first driven gear that is relatively non-rotatable as one element, and the input-side second drive gear supported so as to be relatively rotatable on the main drive shaft; An input side first driven gear is operably connected to the input side second drive gear and is non-rotatable relative to the second element.

In this case, the input side clutch unit is of a dog clutch type having an input side slider as the slider.
The input-side slider is supported by the main drive shaft between the input-side first and second drive gears so as to be non-rotatable relative to and axially movable. While the engaging portion is disengaged from the uneven engagement portion of the second input side drive gear, the first uneven engagement portion is engaged with the uneven engagement portion of the first input side drive gear. Thus, only the input-side first clutch mechanism is engaged, and when the first clutch mechanism on the input side is positioned at the second position, the first concave-convex engaging portion is disengaged from the concave-convex portion engaging portion of the input-side first drive gear. While being engaged, the second uneven engagement portion is engaged with the uneven engagement portion of the second input side drive gear, so that only the second input side clutch mechanism is brought into the engaged state and is placed in the intermediate position. position, the first and second uneven engagement portions are respectively engaged with the uneven engagement portions of the input side first and second drive gears, thereby engaging both the first and second clutch mechanisms. It is configured to bring it into a matching state.

In the transmission structure according to the first aspect, a transmission intermediate shaft connected to the second element so as not to rotate relative to an axis may be provided, and the first element may be supported by the transmission 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 by the speed change intermediate shaft so as not to rotate relative to the speed change intermediate shaft, and to the output side first drive gear, and is relatively connected to the speed change output shaft. and an output-side first driven gear rotatably supported, the output-side second transmission mechanism comprising: an output-side second drive gear connected to the first element so as not to rotate relatively; and the output-side second drive gear. and an output-side second driven gear operatively connected to the two drive gears and relatively rotatably supported by the speed change output shaft. and a concave-convex engaging portion provided on the second driven gear, and supported by the speed change output shaft between the first and second driven gears on the output side so as to be relatively non-rotatable and axially movably supported; and an output-side slider provided with first and second concave-convex engaging 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 engagement of the uneven engagement portion with the uneven engagement portion of the output side first driven gear, only the output side first clutch mechanism is brought into the engaged state, 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 the concave-convex engagement portion of the output side second driven gear. Only the output side second clutch mechanism is engaged by engaging with the portion, and when it is positioned at an intermediate position between the first position and the second position with respect to the axial direction, the first and second clutch mechanisms are engaged. The concave-convex engaging portions are engaged with the concave-convex engaging portions of the output-side first and second drive gears, respectively, so that both the output-side first and second clutch mechanisms are engaged. be done.

In another form that produces the dual transmission state, an input-side clutch unit formed by the input-side first and second clutch mechanisms and an output-side clutch formed by the output-side first and second clutch mechanisms At least one of the units is of a hydraulically actuated friction plate type that is supplied with pressurized oil to create a clutch engagement state.

In this case, the transmission structure includes a pressurized oil supply line that receives pressurized oil from a hydraulic source, and supplies and discharges pressurized oil to and from the first and second clutch mechanisms in the hydraulically operated friction plate type clutch unit. First and second supply/discharge lines, and first and second electromagnetic valves respectively interposed in the first and second supply/discharge lines, wherein the discharge position for draining the corresponding supply/discharge lines and the corresponding supply/discharge lines are provided. First and second electromagnetic valves that can take a supply position for fluidly connecting a discharge line to the pressure oil supply line, and clutch engagement detection that detects engagement states of the first and second clutch mechanisms in the friction plate type clutch unit. means.

The control device positions the first solenoid valve at the supply position and positions the second solenoid valve at the discharge position when the rotation speed of the speed change output shaft is lower than the switching speed, thereby causing the speed change output shaft to rotate at a low speed. In a high-speed state where the rotation speed is equal to or 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. While maintaining the solenoid valve positioned at the supply position at the supply position, the solenoid valve positioned at the discharge position at the time before switching is moved from the discharge position to the supply position, and the position is moved from the discharge position to the supply position. After a predetermined time has elapsed from the time when it was recognized based on the signal from the clutch engagement detection means that the clutch mechanism supplied with pressure oil via the solenoid valve was engaged, the supply position was changed to the supply position at the time before switching. is configured to move a solenoid valve that has been positioned in 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 pilot pressure, so that the hydraulic pressure of the corresponding supply/discharge line is controlled in a state where the position signal to the supply position is input from the control device. is a proportional solenoid valve configured to maintain the hydraulic pressure at engagement.

In the first and second aspects of the present invention, the input-side first and second clutch mechanisms may be of a hydraulically operated friction plate type that receives pressurized oil supply to create a clutch engagement state.
In this case, the transmission structure includes a pressurized oil supply line for receiving pressurized oil from a hydraulic source, and input-side first and second clutch mechanisms for supplying and discharging pressurized oil to and from the input-side first and second clutch mechanisms, respectively. 2 supply/discharge lines, discharge positions inserted respectively in the first and second supply/discharge lines on the input side to drain the corresponding supply/discharge lines, and supply fluidly connecting the corresponding supply/discharge lines to the pressure oil supply line. Input-side first and second electromagnetic valves that can take a position, and clutch engagement detection means for detecting the engagement state of the input-side first and second clutch mechanisms are provided.

Preferably, the control device positions the first input-side electromagnetic valve at the supply position and positions the second input-side electromagnetic valve at the discharge position when the rotational speed of the speed change output shaft is less than the switching speed. In a high-speed state where the rotation speed of the speed change output shaft is equal to or higher than the switching speed, the first input-side electromagnetic valve is positioned at the discharge position and the second input-side electromagnetic valve is positioned at the supply position. and at the time of switching the second transmission state, the solenoid valve that was positioned at the discharge position before switching is moved from the discharge position while maintaining the solenoid valve that was positioned at the supply position at the time before switching at the supply position. Based on the signal from the clutch engagement detection means, it is recognized that the clutch mechanism to which pressure oil is supplied through the electromagnetic valve moved from the discharge position to the supply position is in the slipping engagement state. At the point in time, the solenoid valve, which was positioned 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 pressurized oil supply line for receiving pressurized oil from a hydraulic source, and output-side first and second output-side supply/discharge lines for supplying and discharging pressurized oil to and from the output-side first and second clutch mechanisms, respectively. and the first and second supply/discharge lines on the output side, respectively. output-side first and second solenoid valves, and clutch engagement detection means for detecting the engagement state of the output-side first and second clutch mechanisms.

In this case, preferably, the control device positions the first output side solenoid valve at the supply position and discharges the second output side solenoid valve when the rotation speed of the speed change output shaft is less than the switching speed. position, and in a high-speed state where the rotation speed of the speed change output shaft is equal to or higher than the switching speed, the first output-side solenoid valve is positioned at the discharge position and the second output-side 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 positioned at the supply position before switching is maintained at the supply position, and the solenoid valve that was positioned at the discharge position before switching is moved from the discharge position. Based on the signal from the clutch engagement detection means, it is recognized that the clutch mechanism to which pressure oil is supplied through the electromagnetic valve moved from the discharge position to the supply position is in the slipping engagement state. At the point in time, the solenoid valve, which was positioned 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 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 clutch mechanisms.

A transmission structure according to the present invention includes a pressure oil supply line whose upstream side is fluidly connected to a hydraulic source, a drain line, and a first supply/discharge line for supplying and discharging pressure oil to and from the input side and output side first clutch mechanisms. a line, a second supply/discharge line for supplying and discharging pressure oil to and from the input side and output side second clutch mechanisms, and a switching valve whose position is controlled by the control device.

The switching valve has a first position in which 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 a second position in which the fluid connection is made to a drain line and the pressure oil supply/discharge line is fluidly connected to the second supply/discharge line, wherein the first and second clutch mechanisms on the input side and the output side. The first and second clutch mechanisms are hydraulically actuated to receive pressure oil supply to engage the power transmission of the corresponding transmission mechanism.

Further, in order to achieve the first object, a third aspect of the present invention is a transmission structure interposed in a travel system transmission path of a work vehicle, wherein rotation is operatively input from a drive source to a pump shaft. an HST for outputting power from a motor shaft by steplessly shifting power to at least a first HST speed to a second HST speed according to the operating position of the output adjusting member; a planetary gear mechanism in which three elements act as an input part for HST output; a speed change output shaft; a second transmission mechanism; an input-side first clutch mechanism and an input-side second clutch mechanism for engaging and disengaging power transmission of the input-side first transmission mechanism and the input-side second transmission mechanism, respectively; an output-side first and second clutch mechanism for engaging and disengaging power transmission from a first element to the shift output shaft, a shift operating member, and an HST sensor for directly or indirectly detecting the shift state of the HST; Operation control of an output sensor that directly or indirectly detects the rotation speed of the shift output shaft, the output adjustment member, the input side first and second clutch mechanisms, and the output side first and second clutch mechanisms at least one of an input side clutch unit formed by the input side first and second clutch mechanisms and an output side clutch unit formed by the output side first and second clutch mechanisms, The transmission structure is of a hydraulically actuated friction plate type in which a clutch engagement state is realized by receiving pressure oil supply. first and second supply/discharge lines for supplying and discharging pressurized oil to and from the first and second clutch mechanisms in the friction plate type clutch unit; and a second solenoid valve, which can assume 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; clutch engagement detection means for detecting the engagement state of the first and second clutch mechanisms in the actuated friction plate type clutch unit, the control device, based on the detection signals of the HST sensor and the output sensor, When the rotational speed of the speed change output shaft is in a low speed state below a predetermined switching speed, the input side and output side first clutch mechanisms are engaged and the input side and output side second clutch mechanisms are disengaged. while creating a first transmission state in which the first element acts as an input portion of the reference power operatively transmitted from the drive source and the second element acts as an output portion of the combined rotational power, While the output adjustment member is actuated so that the HST output shifts from the first HST speed toward the second HST speed in accordance with the speed increasing operation of the speed change operation member, the rotation speed of the speed change output shaft is set to a high speed equal to or higher than the switching speed. In the state, the input side and output side first clutch mechanisms are disengaged and the input side and output side second clutch mechanisms are engaged, thereby causing the first element to act as an output portion and the While creating the second transmission state in which the two elements act as the input portion of the reference power, the HST output shifts from the second HST speed toward the first HST speed according to the speed increasing operation of the speed change operation member. The output adjusting member is actuated, and when switching between the first and second transmission states, one of the first and second electromagnetic valves, which was positioned at the supply position before switching, is maintained at the supply position. Then, the other of the first and second solenoid valves, which was positioned at the discharge position before switching, is moved from the discharge position to the supply position, and the clutch mechanism supplied with pressure oil via the other solenoid valve is operated. When it is recognized based on the signal from the clutch engagement detection means that the slipping engagement state has been established, the one electromagnetic valve is moved from the supply position to the discharge position, whereby the first and first clutches in the friction plate clutch unit are operated. To provide a transmission structure configured to switch between engagement and disengagement of a two-clutch mechanism.

Further, in order to achieve the first object, a fourth aspect of the present invention provides a rotary power that is operatively input from a drive source to a pump shaft in accordance with the operating position of an output adjusting member. a planetary gear mechanism having an HST that outputs rotational power from a motor shaft by steplessly changing rotational power between two HST speeds, first to third elements, the third element acting as an input portion of the HST output; an output shaft; input-side first and second transmission mechanisms capable of transmitting the operation of the rotational power of the drive source to the first element and the second element, respectively; and power transmission of the input-side first and second transmission mechanisms. a first and second clutch mechanisms on the input side for engaging and disengaging each of the first and second clutch mechanisms, a first forward transmission mechanism capable of transmitting the rotational power of the second element and the first element respectively to the speed change output shaft in a forward rotation state, and a forward a second transmission mechanism; a reverse transmission mechanism capable of transmitting the rotational power of the second element to the speed change output shaft in a reversed state; power of the first forward transmission mechanism, the second forward transmission mechanism, and the reverse transmission mechanism; A first forward clutch mechanism, a second forward clutch mechanism, and a reverse clutch mechanism that respectively engage and disengage transmission; 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 a rotational speed; the output adjusting member; the first input-side clutch mechanism; the second input-side clutch mechanism; the first forward clutch mechanism; the second forward clutch mechanism; a control device for controlling the operation of the reverse clutch mechanism, wherein the control device adjusts the rotation speed of the shift output shaft from zero speed to less than switching speed in the forward direction based on detection signals from the HST sensor and the output sensor. In the low-speed state of (1), the first forward transmission state in which the first input side clutch mechanism and the first forward clutch mechanism are engaged is realized, and according to the forward speed increasing operation of the speed change operation member The output adjustment member is actuated so that the HST output shifts from the first HST speed to the second HST speed, and when the rotational speed of the speed change output shaft is higher than the switching speed in the forward direction, the input side second speed is operated. The HST output is changed from the first HST speed to the second HST speed in accordance with the forward speed increasing operation of the speed change operation member while the forward second transmission state in which the clutch mechanism and the forward second clutch mechanism are engaged is realized. In a reverse transmission state in which the rotational speed of the speed change output shaft changes from zero speed to the reverse side, the first input side clutch mechanism and the reverse clutch mechanism are engaged. The output adjusting member is actuated so that the HST output shifts from the first HST speed to the second HST speed in accordance with the speed increasing operation on the reverse side of the shift operating member while creating the reverse transmission state that is the engaged state. To provide a transmission structure configured to:

In the fourth aspect, the input-side first transmission mechanism 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. 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 rotation speed of the second element when the HST output is set to the second HST speed in the first forward transmission state and the second forward 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 as the rotational speed of the second element, and the HST output is set to the second HST speed in the forward 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 through the input side first transmission mechanism in the forward first transmission state.

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 a forward first gear ratio, and the forward second transmission mechanism operates the first element male. Rotational power is transmitted to the speed change output shaft at the second forward gear ratio.
In this case, preferably, the forward first and second gear ratios are such that the rotation speed appearing on the gear shift output shaft is the same in the first and second transmission states when the HST output is set to 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 first input side clutch mechanism, the rotation speed of the second element is set to zero speed. and the planetary gear mechanism is set.

Further, in order to achieve the first object, a fifth aspect of the present invention provides a rotary power input from a drive source to a pump shaft, which is shifted from at least the first HST speed to the first speed according to the operating position of an output adjusting member. a planetary gear mechanism having an HST that outputs rotational power from a motor shaft by steplessly changing rotational power between two HST speeds, first to third elements, the third element acting as an input portion of the HST output; an output shaft; an input-side first transmission mechanism capable of transmitting operation of the rotational power of the drive source to the first element at an input-side first speed ratio; a second input-side transmission mechanism capable of transmitting operation to a second element; and a first input-side clutch mechanism and a second input-side clutch mechanism for engaging and disengaging power transmission of the first input-side transmission mechanism and the second input-side transmission mechanism, respectively. a clutch mechanism, a first output-side transmission mechanism capable of transmitting the rotational power of the second element to the speed change output shaft at a first output-side gear ratio, and a second output-side gear ratio for transmitting the rotational power of the first element. an output side second transmission mechanism capable of transmitting operation to the speed change output shaft; a third output-side transmission mechanism capable of transmitting an operation to a shift output shaft; first to third output-side clutch mechanisms for engaging and disengaging power transmission of the first to third output-side transmission mechanisms; and 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, the output adjusting member, and the input side first and second clutches. and a control device that controls the operation of the output side first to third clutch mechanisms, and the control device controls the rotation speed of the shift output shaft based on detection signals from the HST sensor and the output sensor is less than the first switching speed, the first input-side clutch mechanism is engaged and the input-side second clutch mechanism is disengaged, while the first output-side first clutch mechanism is engaged. and by disengaging the other output side clutch mechanism, the first element acts as an input portion of the reference power operatively transmitted from the drive source, and the second element outputs the combined rotational power. operating the output adjusting member so that the HST output shifts from the first HST speed toward the second HST speed in accordance with the speed increasing operation of the speed change operating member while creating the first transmission state acting as a part; In an intermediate speed state in which the rotational 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 first input side clutch mechanism is disengaged and the second input side clutch mechanism is engaged. At the same time, by engaging the second output-side clutch mechanism and disengaging the other output-side clutch mechanism, the second element acts as an input portion for the reference power and the rotational power of the first element. to the speed change output shaft at the output side second gear ratio, the HST output is shifted from the second HST speed toward the first HST speed in accordance with the speed increasing operation of the speed change operation member. When the output adjusting member is actuated so as to shift the speed, and the rotation speed of the speed change output shaft is in a high speed state equal to or higher than the second switching speed, the input side first clutch mechanism is disengaged and the input side second clutch mechanism is disengaged. is engaged, the third output-side clutch mechanism is engaged, and the other output-side clutch mechanism is disengaged, so that the second element acts as an input portion for the reference power and the third clutch mechanism is engaged. While creating a third transmission state in which the rotational power of one element is transmitted to the speed change output shaft at the output side third gear ratio, the HST output is shifted to the second HST speed side according to the speed increasing operation of the speed change operation member. to the first HST speed side, while operating the output adjusting member so as to shift the speed from the second speed to the first HST speed side, and at the time of switching between the second and third transmission states, the rotation appearing on the speed change output shaft in the transmission state after switching The output adjusting member is actuated so that the speed matches or approaches the rotation speed appearing on the speed change output shaft in the transmission state before switching, and the input side first and second gear ratios are set to the first gear ratio. The rotation speed of the second element when the HST output is set to the second HST speed in the transmission state, and the rotation speed of the second element due to the rotational power transmitted via the input side second transmission mechanism in the second transmission state. The rotational speed of the first element when the rotational speed is the same and the HST output is set to the second HST speed in the second transmission state and the input side first transmission mechanism in the first transmission state. Provided is a transmission structure that is set so that the rotational speed of the first element due to transmitted rotational power is the same.

In the various configurations of the fifth aspect, the transmission structure includes: a speed change intermediate shaft connected to the second element so as not to rotate relative to the axis; and a transmission transmission shaft 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 relatively rotatably on the main drive shaft operatively connected to the drive source, and the input-side first drive gear. and a first input-side driven gear that is non-rotatable relative to the transmission transmission shaft, and the second input-side transmission mechanism is a second input-side driving gear that is relatively rotatably supported by the main drive shaft. and an input-side first driven gear that is operatively connected to the input-side second drive gear and that is non-rotatable relative to the second element, wherein the output-side first transmission mechanism is connected to the speed change intermediate shaft. an output-side first drive gear supported so as not to rotate relatively; and an output-side first driven gear operatively connected to the output-side first drive gear and supported relatively rotatably to the speed change output shaft; The output-side second transmission mechanism includes: an output-side second drive gear supported by the speed change transmission shaft so as not to rotate relative to the speed change transmission shaft; and a supported output side second driven gear, and the output side third transmission mechanism includes: an output side third drive gear supported by the speed change transmission shaft so as not to relatively rotate; and the output side third drive gear. and an output side third driven gear which is operatively connected to and supported by the speed change output shaft so as to be relatively rotatable.

The transmission structure according to the present invention further comprises a travel transmission shaft arranged downstream in the transmission direction from the speed change output shaft, and a driving force rotating direction forward and backward between the speed change output shaft and the travel transmission shaft. A forward/reverse switching mechanism capable of switching between directions may be provided.

Further, in order to achieve the first object, a sixth aspect of the present invention provides a rotary power that is operatively input from a drive source to a pump shaft in accordance with the operating position of an output adjusting member. a planetary gear mechanism having an HST that continuously changes rotational power between two HST speeds and outputs it from a motor shaft; first to third elements; the third element acting as an input portion for the HST output; An input-side first transmission mechanism capable of transmitting the rotational power of a drive source to the first element at an input-side first gear ratio; and a rotational power of the drive source to the second element at an input-side second gear ratio. a second input-side transmission mechanism capable of transmission; a first input-side clutch mechanism and a second input-side clutch mechanism for disengaging power transmission of the first input-side transmission mechanism and the second input-side transmission mechanism, respectively; an output shaft, a travel transmission shaft disposed downstream of the speed change output shaft in the transmission direction, and a transmission path inserted from the speed change output shaft to the travel transmission shaft to rotate the travel transmission shaft in the forward direction. a forward/reverse switching mechanism capable of switching between a forward transmission state and a reverse transmission state of rotating in a reverse direction; an output-side first transmission mechanism, an output-side second transmission mechanism capable of transmitting the rotational power of the first element to the speed change output shaft at the output-side second gear ratio, and transmitting the rotational power of the first element to the traveling gear. A third output-side transmission mechanism capable of operating and transmitting a driving force in a forward direction to a transmission shaft, wherein the rotational power of the first element is transmitted via the second output-side transmission mechanism and the forward/reverse switching mechanism in a forward transmission state. When the rotational power of the first element is transmitted to the traveling transmission shaft via the output side third transmission mechanism, the rotation speed of the traveling transmission shaft is higher than the rotational speed of the traveling transmission shaft when the operation is transmitted to the traveling transmission shaft. An output side third transmission mechanism having a gear ratio set so that the rotation speed of the traveling transmission shaft of the traveling transmission shaft becomes high, and an output side third transmission mechanism that engages and disengages the power transmission of the output side first to third transmission mechanisms. first to third clutch mechanisms, a shift operation member, an HST sensor that directly or indirectly detects the shift state of the HST, the output adjustment member, the input side first and second clutch mechanisms, and the output and a control device for controlling the operation of the first to third side clutch mechanisms.

In the sixth aspect, the control device
According to the operation of the shift 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 shift operating member moves forward from the zero speed position. When operated in the forward-side low-speed range up to the side first switching speed position, the first input-side clutch mechanism is engaged and the second input-side clutch mechanism is disengaged while the second clutch mechanism is disengaged. By engaging the first clutch mechanism on one output side and disengaging the clutch mechanism on the other output side, the first element acts as an input portion of the reference power that is operatively transmitted from the drive source. The forward/reverse switching mechanism is brought into the forward transmission state while the second element is acting as an output portion of the combined rotational power, and the forward/reverse switching mechanism is brought into the forward transmission state, and in accordance with the speed increasing operation of the speed change operation member. operating the output adjusting member so that the HST output shifts from the first HST speed side toward the second HST speed side;
when the speed change operation member is operated in a forward intermediate speed range between the first forward switching speed position and the second forward switching speed position, the first input clutch mechanism is disengaged; By engaging the second input-side clutch mechanism, engaging the second output-side clutch mechanism, and disengaging the other output-side clutch mechanisms, the second element is used to input the reference power. a second transmission state in which the rotational power of the first element is transmitted to the speed change output shaft at a second gear ratio on the output side, while bringing the forward/reverse switching mechanism into the forward transmission state; and operating the output adjustment member so that the HST output shifts from the second HST speed side toward the first HST speed side in accordance with the speed increasing operation of the shift operation member;
When the speed change operation member is operated in a forward high speed range exceeding the second forward switching speed position, the first input side clutch mechanism is disengaged and the second input side clutch mechanism is engaged. By engaging the output-side third clutch mechanism and disengaging the other output-side clutch mechanism, the second element acts as an input portion for the reference power and rotates the first element. The HST output is increased in accordance with the speed increasing operation of the speed change operation member while the third transmission state in which the power is transmitted to the traveling transmission shaft as the driving force in the forward direction through the output side third transmission mechanism is realized. actuating the output adjusting member so as to shift from the second HST speed side toward the first HST speed side;
When the speed change operating member passes through the forward second switching speed position between the forward intermediate speed range and the forward high speed range, the rotation of the traveling transmission shaft in the transmission state that appears immediately after passing through. actuating the output adjustment member so that the speed matches or approaches the rotational speed of the travel output shaft in the transmission state that appears immediately before passage;
When the speed change operation member is operated in the reverse side low speed range from the zero speed position to the reverse side first switching speed position, the forward/reverse switching mechanism is operated while the first transmission state is brought about. activating the output adjusting member so that a reverse transmission state is established, and the HST output shifts from the first HST speed side to the second HST speed side in accordance with the speed increasing operation of the shift operating member;
when the speed change operation member is operated in the reverse high speed range exceeding the first reverse speed switching position, causing the forward/reverse switching mechanism to enter the reverse transmission state while exhibiting the second transmission state; Further, the output adjustment member is actuated so that the HST output shifts from the second HST speed side toward the first HST speed side according to the speed increasing operation of the speed change operation member.

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

The transmission structure according to the sixth aspect may include a transmission 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 supported relatively rotatably by the input-side first drive gear supported by the main drive shaft operatively connected to the drive source, and by the speed change intermediate shaft. the input side first driving gear and the input side first driven gear operatively connected to the first element, the input side second transmission mechanism being rotatable relative to the main drive shaft; a supported input-side second driving gear; and an input-side second driven gear operatively connected to the input-side second driving gear while being supported by the transmission intermediate shaft so as not to rotate relative thereto; The first side transmission mechanism has an output side first driven gear operatively connected to the input side second driven gear while being relatively rotatably supported by the speed change output shaft, and the output side second transmission mechanism. has an output-side second driven gear operatively connected to the input-side first driven gear while being relatively rotatably supported by the speed change output shaft; and the output-side third transmission mechanism includes the traveling transmission It may have an output side third driven gear operatively connected to one of the output side first and second output side driven gears while being relatively rotatably supported on the shaft.

The input side first and second clutch mechanisms are respectively 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, and the output side first and second clutch mechanisms are respectively supported by the main drive shaft. Two clutch mechanisms are respectively supported by the speed change output shaft so as to engage and disengage the output side first and second driven gears with the speed change output shaft. A driven gear is supported by the travel transmission shaft so as to be engaged with and disengaged from the travel 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 second bearing plate removably coupled to the housing body at spaced apart locations.

In this case, the main drive shaft, the transmission intermediate shaft, the transmission output shaft, and the traveling transmission shaft are supported by the first and second bearing plates in parallel with each other. The drive gear and the input side first and second clutch mechanisms are arranged such that the input side first and second clutch mechanisms are positioned between the input side first and second drive gears with respect to the axial direction of the main drive shaft. In the state, the input-side first and second driven gears are supported by a portion of the main drive shaft positioned within the partitioned space between the first and second bearing plates, and the input side first and second driven gears are axially aligned with In a state of being positioned at the same position as the input side first and second driving gears, the output side first and second driven gears and the output side driven gears are supported by a portion of the speed change intermediate shaft located in the partitioned space. The output side first and second clutch mechanisms are arranged such that the output side first and second driven gears are positioned at the same axial positions as the input side second and first driven gears, respectively, and the output side first and second clutch mechanisms A second clutch mechanism is axially positioned between the input side first and second driven gears, is supported by a portion of the speed change output shaft positioned within the partition space, and is supported by the output side third clutch mechanism. The driven gear and the output side third clutch mechanism are configured such that 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 third clutch mechanism is axially aligned. With respect to the direction, it is located on the opposite side of the output side first and second clutch mechanisms with respect to one of the output side first and second driven gears, and in the traveling transmission shaft in the partitioned space. The forward/reverse switching mechanism may be supported by a portion of the speed change output shaft and the travel transmission shaft located outside the partitioned space.

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 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 provided on the inner surface of the rear housing main body in the vicinity of the front opening of the rear housing body.

In the fifth aspect and the sixth aspect, the output-side first and second gear ratios are such that when the HST output is set to the second HST speed, the rotational speeds appearing on the shift output shaft are the first and the second speeds. It can be set to be the same in the two transmission states.

Alternatively, at the time of switching between the first transmission state and the second transmission state, the control device is arranged such that the rotation speed appearing at the speed change output shaft in the transmission state after switching is the same as that in the transmission state before switching. It may be configured to actuate the output adjustment member so as to match or approximate the rotation speed appearing on the transmission output shaft.

In the various configurations according to the present invention, when the rotation direction of the rotational power input to the pump shaft is the forward rotation direction, the HST outputs rotational power in one of the forward and reverse directions as the HST output of the first HST speed. and outputs the rotational power in the forward and reverse direction on the other side 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 form the first, second and third elements, respectively.

In order to achieve the other object, the present invention is provided in any one of claims 1 to 7, wherein the present invention is interposed in a drive source, drive wheels, and a running system transmission path from the drive source to the drive wheels. and a transmission structure, wherein the switching speed of the speed change output shaft is set higher than the working speed range.

According to the transmission structures according to the first and second aspects of the present invention, the rotational speed of the shift output shaft is increased to the switching speed in response to the shift of the HST output from the first HST speed to the second HST speed. 1 transmission state and the second transmission state in which the rotation speed of the shift output shaft is increased from the switching speed in accordance with the shift of the HST output from the second HST speed to the first HST speed. It is possible to increase the speed change range of the speed change output shaft, and to effectively prevent or reduce the occurrence of a rotational speed difference in the speed change output shaft 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 ratio of the first and second transmission mechanisms on the input side is adjusted so that the rotation speed difference does not occur in the transmission output shaft when switching between the first and second transmission states. Since there is no need 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 design of the device can be improved. Furthermore, it is possible to suppress the shock at the time of engagement of the clutch mechanism, and it is possible to suppress unintended power cut-off and power deceleration at the time of engagement switching of the clutch mechanism under high-load running conditions.

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

According to the transmission structure according to the fifth aspect of the present invention, the rotational speed of the shift output shaft is increased to the first switching speed in accordance with the shift of the HST output from the first HST speed to the second HST speed. a transmission state, a second transmission state in which the rotation speed of the speed change output shaft is increased from the first switching speed in response to the HST output being shifted from the second HST speed to the first HST speed, and a second transmission state in which the HST output is shifted to the second HST speed. The speed change range of the speed change output shaft is increased by developing a third transmission state in which the rotational speed of the speed change output shaft is increased from the second switching speed in response to the shift from the side of the first HST to the side of the first HST. Furthermore, it is possible to effectively prevent or reduce the occurrence of a rotational speed difference in the transmission output shaft when switching between the first and second transmission states and switching 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 operating 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 is zero, and the shift operating member During operation in the forward low speed range from the zero speed position to the forward first switching speed position, the first element of the planetary gear mechanism receives the reference power from the drive source and the second element. A first transmission state in which the combined rotational power is output is generated, and the combined rotational power is transmitted to the traveling transmission shaft via the forward/rearward movement switching mechanism in the forward transmission state, while the speed-increasing operation of the speed change operation member is performed. Accordingly, the HST output is shifted from the first HST speed side to the second HST speed side, and the speed change operation member shifts to the forward intermediate speed between the forward side first switching speed position and the forward side second switching speed position. When operated within the range, a second transmission state is produced in which the reference power is input to the second element and the combined rotational power is output from the first element, and the combined rotational power is forward transmission state. The HST output is shifted from the second HST speed side to the first HST speed side in accordance with the speed increasing operation of the speed change operation member while transmitting the operation to the traveling transmission shaft via the forward/reverse switching mechanism. 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, causing the combined rotation. The HST output is shifted to the second HST speed according to the speed increasing operation of the speed change operation member while the third transmission state in which the power is transmitted as forward driving force to the travel transmission shaft via the output side third transmission mechanism is realized. side toward the first HST speed side, and when the gear shift operation member passes through the forward second switching speed position between the forward intermediate speed range and the forward high speed range, immediately after passing The HST output is changed so that the rotation speed of the travel transmission shaft in the emerging transmission state matches or approaches the rotation speed of the travel output shaft in the transmission state appearing immediately before passing, When the speed change operation member is operated in the reverse side low speed range from the zero speed position to the reverse side first switching speed position, the first transmission state is produced, and the combined rotational power is transferred to the reverse transmission. The HST output is shifted from the first HST speed side to the second HST speed side in accordance with the speed increasing operation of the speed change operation member while transmitting to the traveling transmission shaft via the forward/reverse switching mechanism in the state of When the speed change operation member is operated in the reverse high speed range exceeding the reverse first switching speed position, the second transmission state is brought about, and the combined rotational power is switched to the reverse transmission state. The HST output is shifted from the second HST speed side to the first HST speed side in accordance with the speed increasing operation of the shift operation member while transmitting to the travel transmission shaft via the mechanism. When switching between the first and second transmission states and switching between the second and third transmission states, it is possible to effectively prevent or reduce the occurrence of rotational speed differences in the traveling transmission shaft, and to move forward, which is frequently used. It is possible to expand the shift range on the running side.

FIG. 1 is a schematic diagram of transmission of a work vehicle to which a transmission structure according to Embodiment 1 of the present invention is applied. FIG. 2 is a hydraulic circuit diagram of the transmission structure according to the first embodiment. FIGS. 3(a) and 3(b) are graphs showing the relationship between the traveling vehicle speed and the HST output in a work vehicle to which the transmission structure according to the first embodiment is applied. 2 is a graph of a low speed stage engaged state and a high speed stage engaged state of the auxiliary transmission mechanism. FIG. 4 is a hydraulic circuit diagram of a transmission structure according to Embodiment 2 of the present invention. FIGS. 5(a) and 5(b) are graphs showing the relationship between the traveling vehicle speed and the HST output in a working vehicle to which the transmission structure according to the second embodiment is applied. 2 is a graph of a low speed stage engaged state and a high speed stage engaged 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 a work vehicle to which the transmission structure according to the modified example of the second embodiment is applied. 2 is a graph of a low-speed stage engagement state and a high-speed stage engagement state of an auxiliary transmission mechanism provided in the . FIG. 7 is a hydraulic circuit diagram of a transmission structure according to Embodiment 3 of the present invention. FIG. 8 is a hydraulic waveform diagram when 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 a transmission structure according to Embodiment 4 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 addition, it shows a state in which the input side second clutch mechanism is in the disengaged state. 11 is a partial cross-sectional view of the vicinity of the input side clutch unit shown in FIG. 10, in which both the input side first and second clutch mechanisms are engaged when the input side slider is positioned at an intermediate position. This indicates that the FIG. 12 is a hydraulic waveform diagram when 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 modifications 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 modified example. FIG. 15 is a hydraulic waveform diagram when switching from the first transmission state to the second transmission state in the transmission structure according to Embodiment 5 of the present invention. FIG. 16 is a hydraulic circuit diagram of a transmission structure according to Embodiment 6 of the present invention. FIG. 17 is a hydraulic waveform diagram when switching from the first transmission state to the second transmission state in the transmission structure according to Embodiment 6 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 modifications of the fifth and sixth embodiments. FIG. 19 is a transmission schematic diagram of a work vehicle to which a transmission structure according to Embodiment 7 of the present invention is applied. FIG. 20 is a hydraulic circuit diagram of the transmission structure according to the seventh embodiment. FIGS. 21(a) and 21(b) are graphs showing the relationship between the traveling vehicle speed and the HST output in a work vehicle to which the transmission structure according to the seventh embodiment is applied. 2 is a graph of a low speed stage engaged state and a high speed stage engaged state of the auxiliary transmission mechanism. FIG. 22 is a hydraulic circuit diagram of a transmission structure according to a modification of the seventh embodiment. FIG. 23 is a transmission schematic diagram of a work vehicle to which the transmission structure according to Embodiment 8 of the present invention is applied. 24 is a partial longitudinal side view of the working 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. FIG. 26 is a transmission schematic 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 transmission schematic diagram of a work vehicle to which the transmission structure according to Embodiment 9 of the present invention is applied. 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. FIG.

Embodiment 1
An embodiment of a transmission structure according to the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows a transmission schematic diagram of a work vehicle 200 to which a transmission structure 1 according to the present embodiment is applied.
2 shows a hydraulic circuit diagram of the transmission structure 1. As shown in FIG.

As shown in FIGS. 1 and 2, the work vehicle 200 includes a drive source 210, drive wheels 220, and the transmission structure 1 interposed in a traveling system transmission path from the drive source 210 to the drive wheels 220. and 1 and 2 denotes a flywheel included in the driving source 210. As shown in FIG.

As shown in FIGS. 1 and 2, the transmission structure 1 includes a hydrostatic continuously variable transmission mechanism (HST) 10, which cooperates with the HST 10 to form an HMT structure (hydrostatic/mechanical continuously variable transmission structure). A planetary gear mechanism 30, a shift output shaft 45, a shift operation member 90 such as a shift lever whose operation position can be detected by an operation position sensor 92, and an HST sensor that directly or indirectly detects the shift state of the HST 10. 95 a , an output sensor 95 b 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 rotationally driven by the drive source 210, a hydraulic pump 14 supported by the pump shaft 12 so as not to rotate relatively, and the hydraulic pump 14. a hydraulic motor 18 fluidly connected to the pump 14 via a pair of hydraulic oil lines 15 and hydraulically rotationally driven by the hydraulic pump 14; a motor shaft 16 supporting the hydraulic motor 18 so as not to relatively rotate; 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 adjusts the 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 adjustment member 20 (that is, gear ratio) can be changed steplessly.

That is, when the rotational speed of the rotational power that is operationally input to the pump shaft 12 from the drive source 210 is taken as a reference input speed, the HST 10 adjusts the reference input speed according to the operating position of the output adjustment member 20. The rotational power of the first HST speed is steplessly changed to the rotational power of at least the first HST speed to the second HST speed, and is output from the motor shaft 16 .

In this embodiment, as shown in FIG. 1, the pump shaft 12 is connected through a gear train 214 to a main drive shaft 212 that is operably connected to the drive source 210 .

In this embodiment, the HST 10 can switch the direction of rotation of the HST output between normal and reverse.
That is, when the HST 10 rotates in the forward direction at the reference input speed, when the output adjusting member 20 is positioned at the first operating position, the direction of rotation of the HST 10 changes from the motor shaft 16 to one of the forward and reverse directions ( When the rotational power of the first HST speed is output and the output adjustment member 20 is positioned at the second operating position, the rotation direction of the motor shaft 16 is set to the other side (for example, the forward direction) of the motor shaft 16. (rotating direction) to output the rotational power of the second HST speed.

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

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

When the movable swash plate is positioned at the neutral position, the pressure oil is no longer discharged from the hydraulic pump 14, and the HST 10 is in a neutral state in which the output of the hydraulic motor 18 is zero.
When the movable swash plate is swung from the neutral position to the forward rotation side on one side of the swing shaft, pressure oil is supplied from the hydraulic pump 14 to one of the pair of hydraulic oil lines 15, The hydraulic line 15 is on the high pressure side and the other working line 15 is on the low pressure side.
As a result, the hydraulic motor 18 is rotationally driven in the forward rotation direction, and the HST 10 is brought into the forward rotation output state.

Conversely, when the movable swash plate is swung from the neutral position to the reverse rotation side on the other side of the swing shaft, pressure oil is supplied from the hydraulic pump 14 to the other of the pair of hydraulic oil lines 15, One 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 in the reverse direction, and the HST 10 is in a reverse rotation 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 controlled by the control device 100 based on the operation of the shift operating member 90 .
That is, the control device 100 operates the output adjustment member 20 via the actuator 110 based on the operation of the shift operation member 90 .
As long as the actuator 110 is operated and controlled by the control device 100, the actuator 110 can have various configurations such as an electric motor and a hydraulic servomechanism.

The planetary gear mechanism 30, as shown in FIGS. and a carrier 38 which supports the planetary gear 34 so as to be rotatable about its axis and rotates about the axis of the sun gear 32 in conjunction with the revolution of the planetary gear 34 about the sun gear 32. The sun gear 32, the carrier 38 and the An internal gear 36 forms a planetary triad.

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 section for inputting the HST output.
As shown in FIGS. 1 and 2, in this embodiment, the sun gear 32 is the third element.
In this embodiment, the sun gear 32 is operatively connected to the motor shaft 16 via a gear train 216. As shown in FIG.

In the transmission structure 1 according to the present embodiment, the first element acts as a reference power input section for inputting the reference rotational power from the drive source 210, and the second element acts as an output section for outputting the combined rotational power. and a second transmission state in which the first element acts as the output section and the second element acts as the reference power input section.

Specifically, as shown in FIGS. 1 and 2, the transmission structure 1 further includes 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. 50(1) and the input side second transmission mechanism 50(2), and the input side for disengaging power transmission between the input side first transmission mechanism 50(1) and the input side second transmission mechanism 50(2), respectively. a first clutch mechanism 60(1), a second clutch mechanism 60(2) on the input side, and a first transmission mechanism on the output side capable of transmitting the rotational power of the second element and the first element to the shift output shaft, respectively; 70(1) and the output side second transmission mechanism 70(2), and the output side that engages and disengages the power transmission of 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 an output side second clutch mechanism 80(2).

In this 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 (the internal gear 36 in the present embodiment) at the input-side first gear ratio. ing.

More specifically, as shown in FIGS. 1 and 2, the input side first transmission mechanism 50(1) includes an input side first drive gear 52(1) coupled to the main drive shaft 212 so as to be relatively rotatable. , and an input-side first driven gear 54(1) meshed with the input-side first driving 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. .

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

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

More specifically, the input side first clutch mechanism 60(1) includes an input side clutch housing 62 that is non-rotatably supported by the main drive shaft 212, and an input side clutch housing 62 that is non-rotatably supported by the input side clutch housing 62. Input-side friction plates including first drive-side friction plates and first driven-side friction plates supported by the input-side first drive gear 52(1) so as to face the first drive-side friction plates so as not to rotate relative to each other. 1 friction plate group 64(1) and an input side first piston (not shown) that frictionally engages the input side first friction plate group 64(1).

The input-side second clutch mechanism 60 (2) includes the input-side clutch housing 62, second drive-side friction plates supported by the input-side clutch housing 62 so as not to rotate relative to each other, and the second drive-side friction plates. An input-side second friction plate group 64(2) including a second driven-side friction plate supported so as not to rotate relative to the input-side second drive gear 52(2) in a facing state; It has an input-side second piston (not shown) that frictionally engages 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 variable speed intermediate shaft 43 that is arranged coaxially with the planetary gear mechanism 30 and is connected to one of the first and second elements so as not to rotate relative to the axis.

In this embodiment, the transmission intermediate shaft 43 is connected to the second element so as not to rotate relative to it.
In addition, the first output-side transmission mechanism 70(1) includes a first output-side drive gear 72(1) supported by the transmission intermediate shaft 43 so as not to rotate relatively, and the first output-side drive gear 72(1). (1) and supported by the transmission output shaft 45 so as to be relatively rotatable.

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). and an output-side second driven gear 74 (2) supported by the speed change output shaft 45 so as to be relatively rotatable.
In this embodiment, the output-side second drive gear 72(2) is supported by the transmission intermediate shaft 43 so as to be relatively rotatable.

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

Specifically, the output side first clutch mechanism 80(1) is relatively rotatable between an 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). An output-side friction plate including a first drive-side friction plate supported so as not to rotate and a first driven-side friction plate supported by the output-side clutch housing 82 so as to face the first drive-side friction plate so as not to rotate relative to the first drive-side friction plate. 1 friction plate group 84(1) and an output side first piston (not shown) that frictionally engages 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 so as not to rotate relative to the output side second driven gear 74(2), and the second drive side friction plate. A second output-side friction plate group 84(2) including second driven-side friction plates supported by the output-side clutch housing 82 so as to face the drive-side friction plates so as not to rotate relative to each other; and an output-side second piston (not shown) that frictionally engages the friction plate group.

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

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

The switching valve 165 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 . and a second position fluidly connecting the first supply/discharge line 160(1) to the drain line 157 and fluidly connecting the pressure oil supply/discharge line 155 to the second supply/discharge line 160(2). configured to obtain.

As shown in FIG. 1, the transmission structure 1 according to the present embodiment further includes a travel transmission shaft 235 arranged downstream in the transmission direction from the speed change output shaft 45, a speed change output shaft 45 and the travel transmission shaft 235. A forward/reverse switching mechanism 230 is provided that can switch the rotational direction of the drive force between the shafts 235 between the forward direction and the reverse direction.

The forward/reverse switching mechanism 230 is configured, for example, so that switching between the forward direction and the reverse direction is performed by the control device 100 according to the operation of the speed change operation member 90 toward the forward direction and the reverse direction.
That is, when the control device 100 recognizes that the speed change operation member 90 has been operated to the forward side, the control device 100 puts the forward/reverse switching mechanism 230 into the forward transmission state, and the speed change operation member 90 is operated to the reverse side. When it recognizes that it has been moved, the forward/reverse switching mechanism 230 is brought into the reverse transmission state.

As shown in FIG. 1, the transmission structure 1 according to the present embodiment further includes a second travel transmission shaft 235 arranged downstream of the travel transmission shaft 235 in the transmission direction, the travel transmission shaft 235 and the second A sub-transmission mechanism 240 is provided between the two traveling transmission shafts 245 and is capable of multi-stage shifting the rotational speed of the driving force in two stages of high speed and low speed.
The sub-transmission mechanism 240 switches between a high-speed transmission state and a low-speed transmission state via a mechanical link mechanism or by the control device, for example, in response to manual operation of a sub-transmission operating member (not shown). is configured to take place.

The work vehicle 200 has a pair of left and right main driving wheels as the driving wheels 220 .
Therefore, as shown in FIG. 1, the working vehicle 200 further includes a pair of main driving axles 250 for driving the pair of main driving wheels, respectively, and a pair of main driving axles 250 for transmitting the rotational power of the second travel transmission shaft 245 to the pair of main driving axles. and a differential mechanism 260 for differential transmission to the driving axle 250 .

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

The work vehicle 200 also includes a PTO shaft 280 that outputs rotational power to the outside, and a PTO clutch mechanism 285 and a PTO multi-speed transmission mechanism 290 that are interposed in a PTO transmission path from the drive source 210 to the PTO shaft 280. have.

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

FIG. 3 shows a graph representing the relationship between the running vehicle speed and the rotation speed of the HST output in the work vehicle 200. As shown in FIG.
3(a) and 3(b) are graphs showing a state in which the auxiliary transmission mechanism 240 is engaged in the low speed stage and the high speed stage, respectively.

The control device 100 controls the rotational speed of the speed change output shaft 45 to a predetermined value based on the detection signal of the output sensor 95b when the speed change operation member 90 is operated up to the switching speed position. In a low speed state (less than high speed), the input side and output side first clutch mechanisms 60(1), 80(1) are engaged and the input side and output side second clutch mechanisms 60(2), 80 are engaged. By disabling (2), the first element (the internal gear 36 in the present embodiment) acts as an input portion for the reference power operatively transmitted from the drive source 210, and the A first transmission state is produced in which the second element (the carrier 38 in this embodiment) acts as an output portion of the combined rotational power.

As long as the output sensor 95b can directly or indirectly recognize the rotation speed of the transmission output shaft 45, the output sensor 95b is a sensor that detects the rotation speed of the transmission output shaft 45, the rotation speed of the drive wheels 20 or the drive axle 250. It can take various forms, such as a sensor that detects .

The low-speed state in which the rotation speed of the transmission output shaft 45 is less than the predetermined switching speed is when the auxiliary transmission mechanism 240 is engaged in the low-speed stage (see FIG. 3(a)). means that it is within the range of -a(L) to +a(L), and -a( H) to +a(H).
"+" and "-" of the traveling vehicle speed mean that the traveling direction of the work vehicle 200 is the forward direction and the backward direction, respectively.

In the first transmission state, the control device 100 adjusts the HST output from the first HST speed (predetermined speed on the reverse rotation side in the present embodiment) 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 actuated so as to shift the gear toward the 2HST speed (in this embodiment, the forward rotation side predetermined speed).

As long as the HST sensor can detect the output state of the HST 10, it can take various forms such as a sensor that detects the rotation speed of the motor shaft 16, a sensor that detects the operating position of the output adjustment member 20, and the like.

That is, the control device 100 causes the first transmission state to appear when the speed change operation member 90 is positioned up to the switching speed position, and then,
(1) When the shift operating member 90 is positioned at the zero speed position (vehicle stop position), the HST output is set to the first HST speed position (in this embodiment, the reverse side predetermined position). position the output adjusting member 20 at the high 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), the traveling vehicle speed of the work vehicle 200 of the present embodiment is As a reference, when the auxiliary transmission mechanism 240 is engaged in the low-speed stage (FIG. 3(a)), the speed changes from zero speed to vehicle speed −a (L) (during reverse), and from zero speed to vehicle speed When the auxiliary transmission mechanism 240 is in the high-speed stage engagement state (Fig. 3(b)), the vehicle speed -a(H) ( (during reverse) and until vehicle speed +a(H) (during forward) is reached from zero speed. (In the present embodiment, the output adjusting member 20 is moved from the reverse rotation side predetermined speed position to the forward rotation side predetermined speed position.) side),
(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), the traveling vehicle speed of the work vehicle 200 of the present embodiment is changed to As a reference, when the auxiliary transmission mechanism 240 is engaged in the low-speed stage (FIG. 3(a)), when the vehicle speed reaches -a(L) (during reverse) and when the vehicle speed +a(L) ( Also, when the auxiliary transmission mechanism 240 is in the high-speed stage engagement state (Fig. 3(b)), the time point reaches -a(H) (reverse), (corresponding to the time when the vehicle speed +a(H) (when moving forward) is reached), and the second HST speed position (in this embodiment, the forward rotation side predetermined speed position) 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 operation member 90 has passed the switching speed position and is operated to the high speed side (that is, based on the detection signal of the output sensor 95b, the speed change output shaft 45 is rotated). When it recognizes 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 brought into the disengaged state and the input side and output side first clutch mechanisms 60(1) and 80(1) are disengaged. By engaging the two clutch mechanisms 60(2) and 80(2), a second transmission state is present in which the first element acts as an output section and the second element acts as an input section for the reference power. let out

A high-speed state in which the rotation speed of the transmission output shaft 45 is equal to or higher than a predetermined switching speed is a state in which the auxiliary transmission mechanism 240 is engaged in a low-speed stage (see FIG. 3(a)). means a state of -a (L) or more (during reverse) or +a (L) (during forward) or more, and when the auxiliary transmission mechanism 240 is engaged with the high speed stage (Fig. 3 ( b)) means that the vehicle speed is -a(H) or higher (reverse) or +a(H) or higher (forward).

In the second transmission state, the control device 100 adjusts the HST output from the second HST speed (predetermined speed on the forward rotation side in the present embodiment) 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 actuated so as to change gears toward the first HST speed (predetermined speed on the reverse rotation side in this embodiment).

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,
(1) When the gear shift operation member 90 is positioned at the switching speed position, it is positioned at the second HST speed position (in the present embodiment, at the forward rotation side predetermined speed position) to set the HST output to the second HST speed. Positioning the output adjustment member 20,
(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 rotational speed of the speed change output shaft 45 reaches the maximum speed from the switching speed ( Based on the traveling vehicle speed of the working vehicle 200 of the present embodiment, when the auxiliary transmission mechanism 240 is engaged in the low speed stage (FIG. 3(a)), the vehicle speed −a(L) changes to the vehicle speed −b( L) (during reverse) and until vehicle speed +a (L) reaches +b (L) (forward). (Fig. 3(b)) shows the vehicle speed from -a(H) to -b(H) (reverse) and from +a(H) to +b(H) (forward). )), and operates the output adjusting member 20 so that the HST output shifts from the second HST speed side to the first HST speed side in accordance with the speed increasing operation of the speed change operating member 90 (this embodiment moves the output adjusting member 20 from the forward rotation side predetermined speed position to the reverse rotation side predetermined speed position),
(3) When the speed change operation 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 (the traveling vehicle speed of the work vehicle 200 of the present embodiment) , when the auxiliary transmission mechanism 240 is engaged in the low-speed stage (FIG. 3(a)), when the vehicle speed reaches -b(L) (reverse), and when the vehicle speed +b(L) In addition, when the auxiliary transmission mechanism 240 is in the high-speed stage engagement state (Fig. 3(b)), the time point reaches -b(H) (reverse). , and when the vehicle speed reaches +b(H) (when moving forward))), the first HST speed position at which the HST output is set to the first HST speed (in the present embodiment, the reverse rotation side predetermined speed position). , the output adjusting member 20 is positioned.

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

That is, in the present embodiment, a first transmission state in which the first element acts as the reference power input section and the second element acts as the output section, and a first transmission state in which the first element acts as the output section and the second The input-side first and second shift gears are arranged so that a rotational speed difference does not occur 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 section. A ratio is set.

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

That is, in the present embodiment, at the timing of switching between the first and second transmission states, the output side first and second gear shifts are controlled so that the speed change output shaft 45, that is, the running vehicle speed does not change. A ratio is set.

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

Furthermore, when switching between the low-speed shift range (first transmission state) and the high-speed shift range (second transmission state), it is not necessary to change the operating position of the output adjustment member 20 of the HST 10, and , and does not cause a change in running vehicle speed.
Therefore, the switching can be performed smoothly without applying a load to the components of the traveling system transmission path in which the transmission structure 1 is inserted.

In addition, the transmission structure 1 generates a speed difference between the low-speed shift range (first transmission state) and the high-speed shift range (second transmission state) without providing a plurality of the planetary gear mechanisms 30. It is possible to switch without causing a shift, thereby realizing good transmission efficiency.

That is, if two or more planetary gear mechanisms are provided, it is not necessary to change the operating position of the output adjusting member of the HST, and the traveling vehicle speed is not changed. It is possible to switch the transmission state in 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, the transmission structure 1 can obtain the above effects by simply including the single planetary gear mechanism 30 as described above.

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 shift range (first transmission state) and the high-speed shift range (second transmission state) can be performed more smoothly.

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

That is, in many cases, work vehicles such as tractors and combine harvesters perform heavy-load work such as plowing work, plowing work, and harvesting work while traveling at low speed.
Generally, in the working vehicle, the traveling vehicle speed when performing such heavy-load work is set as the working speed range, which is usually 0 to 8 Km/h, and 0 to 10 Km/h depending on the specifications. 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 can be performed in a state of heavy load work. It can effectively prevent switching between states from occurring.

Embodiment 2
Hereinafter, another embodiment of a 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 this embodiment.
In the drawings, the same members as in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

The transmission structure 2 according to the present embodiment differs from the transmission structure 1 according to the first embodiment in that the output side first and second transmission mechanisms 70(1) and 70(2) are omitted. do.

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

FIG. 5 shows a graph representing 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 showing a state in which the auxiliary transmission mechanism 240 is engaged in the low speed stage and the high speed stage, respectively.

As shown in FIGS. 5(a) and 5(b), in the present embodiment, the control device 100
When the shift operating member 90 is operated from the zero speed position to the first switching speed position (that is, based on the detection signal of the output sensor 95b, the shift output shaft 45 moves to the predetermined first switching speed in the first transmission state ( Based on the running vehicle speed, -a (L) (1) (reverse) or +a (L) (1) (forward) when low speed gear is engaged, -a (H) when high speed gear is engaged )(1) (during reverse) or +a(H)(1) (during forward)), 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 rotational speed of the first switching speed appears on the shift output shaft 45 .

That is, the reference power from the drive source 210 is operationally input to the first element (in this embodiment, the internal gear 36), and the third element (in this embodiment, the sun gear 32) receives the reference power. Composite rotational power operatively transmitted from the second element (the carrier 38 in this embodiment) when the HST output of the second HST speed is operatively input and the composite rotative power is output from the second element (the carrier 38 in this embodiment) , the speed change output shaft 45 rotates at the first switching speed.

At this time, the running vehicle speed is -a(L)(1) (during reverse) or +a(L)(1) (during forward) when the auxiliary transmission mechanism 240 is engaged in the low speed stage (Fig. 5(a) ), and when the auxiliary transmission mechanism 240 is engaged with the high speed stage, it becomes -a(H)(1) (reverse) or +a(H)(1) (forward) (FIG. 5(b)).

When the speed change operation member 90 is operated to the first switching speed position (that is, when the HST output is set to the second HST speed in the first transmission state and the rotational 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 by, the reference power from the drive source 210 is operatively input to the second element (the carrier 38 in this embodiment), The HST output of the second HST speed is operationally 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). and the speed change output shaft 45 is rotated by the combined rotational power operatively transmitted from the first element.

At this time, as described above, 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). changes from the first switching speed to the second switching speed.

The traveling vehicle speed when the rotation speed of the shift output shaft 45 is the second switching speed is -a(L)(2) (during reverse) or +a(L) when the sub-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 the high speed stage, -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, a rotational speed difference occurs in the speed change output shaft 45 when switching between the first and second transmission states, and the running vehicle speed changes.

However, since the rotational speed difference is not so large, it can be absorbed by the members forming the traveling system transmission path.
In particular, in this embodiment, the input side first and second clutch mechanisms 60(1), 60(2) and the output side first and second clutch mechanisms 80(1), 80(2) are frictionally controlled. A plate-type clutch mechanism is used, and the rotational speed difference can be effectively absorbed by the friction plate-type clutch mechanism.

Instead of this, of the input side first and second clutch mechanisms 60(1) and 60(2), the input side second clutch mechanism 60(2) which 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), which is engaged in the second transmission state, is frictionally controlled. It is also possible to adopt a plate-type clutch mechanism and the remaining clutch mechanisms 60(1) and 80(1) to be of another type such as a dog clutch mechanism.

According to the transmission structure 2 having such a configuration, although a slight difference in running speed occurs when switching between the first and second transmission states, the output side first and second transmission The structure can be simplified by eliminating the mechanisms 70(1) and 70(2).

FIG. 6 shows a graph representing the relationship between the running 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 showing the states in which the auxiliary transmission mechanism 240 is engaged in the low speed stage and the high speed stage, respectively.

In the modified example, when switching between the first transmission state and the second transmission state, the control device 100 causes the switching speed in the transmission state after switching to match or approach the switching speed in the transmission state before switching. , 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 sets the switching speed (second switching speed) in the second transmission state, which is the transmission state after switching, to The output adjusting member 20 is operated 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 this modified example, it is possible to effectively prevent or reduce the occurrence of a rotational speed difference in the speed change output shaft 45 when switching between the first and second transmission states, that is, the occurrence of a running speed difference. .

Embodiment 3
Hereinafter, still another embodiment 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 this embodiment.
In the drawings, the same members as in Embodiments 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

In the transmission structure 3 according to the present embodiment, both the input-side first and second clutch mechanisms 60(1) and 60(2) are in the engaged state during the transitional period of switching between the first and second transmission states. and both of the output side first and second clutch mechanisms 80(1) and 80(2) are in the engaged state. It differs from Structure 1.

Specifically, the transmission structure 3 includes the input side first and second clutch mechanisms 60(1), 60(2) and the output side first and second clutch mechanisms 80(1), 80(2). 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), the output side An input side first supply/discharge line 360(1) and an input side second supply/discharge line 360 for supplying and discharging pressurized oil to the first clutch mechanism 80(1) and the output side second clutch mechanism 80(2), respectively. (2), output side first supply/discharge line 362(1) and output side second supply/discharge line 362(2), pressure oil supply line 155 and input side first supply/discharge line 360(1), input The input side first solenoid valve interposed between each of the 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). 365(1), a second input side solenoid valve 365(2), a first output side solenoid valve 367(1) and a second output side solenoid valve 367(2), and the first input side supply/discharge line 360(1). ), input-side second supply/discharge line 360(2), output-side first supply/discharge line 362(1), and 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).

Said solenoid valves 365(1), 365(2), 367(1), 367(2) drain corresponding supply and exhaust lines 360(1), 360(2), 362(1), 362(2). and a supply position in which the corresponding supply/discharge lines 360(1), 360(2), 362(1), 362(2) are fluidly connected to the pressure oil supply line 155. .
In this embodiment, the solenoid valves 365(1), 365(2), 367(1), 367(2) are biased toward the eject position by biasing members, and the control device 100 When a control signal from is inputted, it is positioned at the supply position against the biasing force of the biasing member.

In this embodiment, as shown in FIG. 7, the solenoid valves 365(1), 365(2), 367(1), 367(2) are connected to corresponding supply/discharge lines 360(1), 360( 2), 362(1), 362(2) as pilot pressure, the corresponding supply/discharge lines 360(1), 360( 2), 362(1), and 362(2) are proportional solenoid valves configured to maintain the hydraulic pressure at the engagement 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 taking as an example a case of switching from the first transmission state 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) at the time of switching from the first transmission state to the second transmission state.

When the shift operating member 90 is positioned between the zero speed position and the switching speed position (that is, when the rotational speed of the shift output shaft 45 is less than the switching speed), the control device 100 ), the input-side first solenoid valve 365(1) and the output-side first solenoid valve 367(1) are positioned at the supply position, and the input-side second solenoid valve 365(2) and the output-side second solenoid Place valve 367(2) in the exhaust position.

In this state, 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 60(2) and the output side clutch mechanism 60(2) are released. While the side second clutch mechanism 80(2) is in the disengaged state, the input side first supply/discharge line 360(1) and the output side first supply/discharge line 362(1) are connected to the corresponding electromagnetic valves 365 ( 1), the engagement oil pressure set by the pilot pressure of 367(1) is maintained, and the first input side clutch mechanism 60(1) and the first output side clutch mechanism 80(1) are engaged. be.
This brings the transmission structure 3 into the first transmission state.

On the other hand, 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), the control device 100 The first input-side solenoid valve 365(1) and the first output-side solenoid valve 367(1) are positioned at the discharge position, and the second input-side solenoid valve 365(2) and the second output-side solenoid valve 367( 2) to the feed position.

In this state, 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 60(1) and the output side first clutch mechanism 60(1) are released. While the side first clutch mechanism 80(1) is in the disengaged state, the input side second supply/discharge line 360(2) and the output side second supply/discharge line 362(2) are connected to the corresponding electromagnetic valves 365. (2) The engagement oil pressure set by the pilot pressure of 367(2) is maintained, and the input side second clutch mechanism 60(2) and the output side second clutch mechanism 80(2) are in the engaged state. be done.
Thereby, the transmission structure 3 is brought into 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 rotational speed of the speed change output shaft 45 is switched based on the signal from the output sensor 95b). When the control device 100 recognizes that the switching speed has been reached from the state below the speed), the control device 100 switches the input position that was located in the supply position at the time before the transmission state switching (in this example, the time of the first transmission state). While maintaining the first side solenoid valve 365 (1) and the first output side solenoid valve 367 (1) at the supply position, the second input side solenoid valve 365, which was positioned at the discharge position before switching, (2) and the output side second solenoid valve 367(2) is moved from the discharge position to the supply position.

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

After that, the control device 100 controls the input side second solenoid valve 365(2) moved to the supply position and the input side second solenoid valve 367(2) supplied with pressure oil via the output side second solenoid valve 367(2). Based on the signals from the corresponding pressure sensors 370(2) and 372(2), the hydraulic pressures of the second supply/discharge line 360(2) and the output side second supply/discharge line 362(2) have reached the engagement hydraulic pressure. At a point in time (time Tc) after a predetermined period of time has elapsed from the point of time (time Tb) when it was recognized, the input side first solenoid valve 365(1) and the output side first solenoid valve 365(1) which were positioned at the supply position at the time before switching 367(1) is moved from the feed position to the eject position.

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

According to the transmission structure 3 according to the present embodiment having such a configuration, it is possible to effectively prevent the occurrence of a state in which the 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 this embodiment, the pressure sensors 370(1), 370(2), 372(1), and 372(2) are configured to detect the engagement state of the corresponding friction plate clutch mechanism. However, instead of this, other clutch engagement detection for detecting the supply current value and supply current time to the proportional solenoid valves 365(1), 365(2), 367(1), 367(2). It is also possible to configure so as to detect the engagement state of the corresponding friction plate type clutch mechanism by means.

Embodiment 4
Hereinafter, still another embodiment of the transmission structure according to the present invention will be described with reference to the attached drawings.
FIG. 9 shows a hydraulic circuit diagram of the transmission structure 4 according to this embodiment.
In the drawings, the same members as in Embodiments 1 to 3 are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

Compared to the transmission structure 1 according to the first embodiment, the transmission structure 4 according to the present embodiment has the friction plate type first and second input-side clutch mechanisms 60(1), 60(2) and the A dog clutch type input side clutch unit 410 and an output side clutch unit 430 are provided instead of the output side first and second clutch mechanisms 80(1) and 80(2).

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

The input-side slider 412 is disposed between the input-side first and second drive gears 52(1) and 52(2), and is positioned on the one axial side adjacent to the input-side first drive gear 52 (19). and a second concave-convex engaging portion 412(2) on the other side in the axial direction close to the input-side second driving gear 52(2). ing.

The input-side clutch unit 410 further includes 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. While being disengaged with the uneven engagement portion 414(2), the first uneven engagement portion 412(1) engages the uneven engagement portion 414(1) of the input side first drive gear 52(1). When engaged, the input side first driving gear 52(1) is coupled to the main drive shaft 212, and the input gear formed by the first uneven portion 412(1) and the uneven portion 414(1) is engaged. Only the side first clutch mechanism is brought into the engaged state.

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 the concave-convex portion of the first input-side driving 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 driving gear 52(2) while being disengaged with the portion 414(1). By doing so, the input side second drive gear 52(2) is connected to the main drive shaft 212, and the input side second drive gear 52(2) formed by the second uneven portion 412(2) and the uneven portion 414(2) is connected. Engage only the clutch mechanism.

Further, when the input-side slider 412 is positioned at an intermediate position between the first and second positions in the axial direction, as shown in FIG. 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 Both first and second drive gears 52(1), 52(2) are coupled to the main drive shaft 212 to engage both the input first and second clutch mechanisms.

That is, when the input-side slider 412 moves between the first position where the first transmission state appears and the second position where the second transmission state appears, the input-side first and An intermediate position is passed which causes both of the second clutch mechanisms to be engaged.

In the transmission structure 4 according to the present embodiment having such a configuration as well, it is possible to effectively prevent the occurrence of a state in which the 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 includes concave-convex engaging portions (not shown) formed in the output-side first and second driven gears 74(1) and 74(2), respectively, and the output clutch unit 430 in the axial direction. and an output-side slider 432 supported by the corresponding speed change output shaft 45 between the side first and second driven gears 74(1) and 74(2) so as to be non-rotatable and axially movable.

The output-side slider 432 has a first concave-convex engaging portion (not shown) on one side in the axial direction adjacent to the output-side first driven gear 74(1), and has a first output-side second driven gear 74(1). It has a second concave-convex engaging portion (not shown) 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 disengages from the concave-convex engaging portion of the output-side second driven gear 74(2). The first output-side driven gear 74(1) is connected to the speed change output shaft 45 by engaging the first uneven engagement portion with the uneven engagement portion of the first output-side driven gear. Then, only the output-side first clutch mechanism formed by the first uneven engagement portion and the uneven engagement portion of the output-side first driven gear 74(1) is engaged.

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 the concave-convex portion engaging portion of the output-side first driven gear 74(1). While being disengaged, the second uneven engagement portion is engaged with the uneven engagement portion of the output side second driven gear 74(2), thereby disengaging the output side second driven gear 74(2). By connecting to the shift output shaft 45, only the output side second clutch mechanism formed by the second uneven engaging portion and the uneven portion of the output side second driven gear 74(2) is engaged.

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 concave-convex engaging portions engage the output-side first and second driven gears 74 . Both the output side first and second driven gears 74(1) and 74(2) are connected to the speed change output shaft 45 by being engaged with the uneven engagement portions (1) and 74(2), respectively. Then, both the output side first and second clutch mechanisms are brought into the engaged state.

The transmission structure 4 according to this 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 includes the pressure oil supply line 155, the drain line 157, and an input side first oil chamber 450 (1) for pushing the input side slider 412 toward the first position by the supplied pressure oil. ), the input-side second oil chamber 450(2) for pushing the input-side slider 412 toward the second position by the supplied pressure oil, and the output-side slider 432 for pushing the output-side slider 432 to the first position by the supplied pressure oil. A first output-side oil chamber 452(1) that pushes toward the position, and a second output-side oil chamber 452(2) that pushes the output-side slider 432 toward the second position by the supplied pressure oil. , a first supply/discharge line 460(1) for supplying and discharging pressure oil to and from the input side first oil chamber 450(1) and the output side first oil chamber 452(1), and the input side second oil chamber 452(1). A second supply/discharge line 460(2) for supplying and discharging pressurized oil to and from 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

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

The solenoid valve 465 fluidly connects the pressure oil supply/discharge line 155 to the first supply/discharge line 460 ( 1 ) and fluidly connects the second supply/discharge line 460 ( 2 ) to the drain line 157 . and a second position that fluidly connects the first supply/discharge line 460(1) to the drain line 157 and fluidly connects the pressure oil supply/discharge line 155 to the second supply/discharge line 460(2). configured to obtain.

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.

When the shift operating member 90 is positioned between the zero speed position and the switching speed position (that is, when the rotational speed of the shift output shaft 45 is less than the switching speed), the control device 100 ), the solenoid valve 465 is positioned at the first position.

In this state, the hydraulic pressure in 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 are moved. Located in the first position.

As a result, the input-side second clutch mechanism and the output-side second clutch mechanism are disengaged, while the input-side first clutch mechanism and the output-side first clutch mechanism are engaged. Structure 4 is in the first transmission state.

The control device 100 moves the solenoid valve 465 to the second position 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). position.

In this state, the hydraulic pressure in 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 are moved. Located in the second position.

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

Here, at time Ta (see FIG. 12), when it is recognized that the shift operation member 90 has been operated from the zero speed position side to the switching speed position (i.e., the shift output is detected based on the signal from the output sensor 95b). Upon recognizing that the rotation speed of the shaft 45 has reached the switching speed from the state below the switching speed, the control device 100 moves the electromagnetic 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 at time Ta toward the second position, and reach the second position at 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, one of the input side clutch unit and the output side clutch unit may be of the friction plate type and the other may be of the dog clutch type.

FIG. 13 shows a hydraulic circuit diagram of a 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 in the transmission structure 5 at the time of switching from the first transmission state to the second transmission state.

Moreover, it is of course possible to apply the configuration relating to the double transmission structure in the third and fourth embodiments to the second embodiment.

Embodiment 5
Hereinafter, still another embodiment 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 electromagnetic valves 365(1), 365(2), 367(1), and 367(2) by the control device 100 when switching between the first and second transmission states are controlled. 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) at the time of switching from the first transmission state to the second transmission state.

When the shift operating member 90 is positioned up to the switching speed position (that is, when the rotational speed of the shift output shaft 45 is lower than the switching speed), the control device 100 controls the electromagnetic Position control similar to that in the third embodiment is performed for the valves 365(1), 365(2), 367(1), and 367(2).

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

In this state, as shown in FIG. 15, the hydraulic pressure in 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 is released. 60(2) and the output side second clutch mechanism 80(2) are in the disengaged state, the input side first supply/discharge line 360(1) and the output side first supply/discharge line 362(1) are The engagement oil pressure set by the corresponding pilot pressures of the electromagnetic valves 365(1) and 367(1) is maintained, and the first input side clutch mechanism 60(1) and the first output side clutch mechanism 80(1) are engaged. ) are engaged.
This places the transmission structure in 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 operates the electromagnetic valve 365 ( 1), 365(2), 367(1), and 367(2) are subjected to the same position control as in the third embodiment.

That is, the control device 100 positions the first input-side solenoid valve 365(1) and the first output-side solenoid valve 367(1) at the discharge position, and the second input-side solenoid valve 365(2) and 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 is released. 60(1) and the output-side first clutch mechanism 80(1) are in the disengaged state, the input-side second supply/discharge line 360(2) and the output-side second supply/discharge line 362(2) are , is maintained at the engagement oil pressure set by the corresponding pilot pressures of the electromagnetic valves 365(2) and 367(2), and the input side second clutch mechanism 60(2) and the output side second clutch mechanism 80 ( 2) is engaged.
Thereby, the transmission structure 3 is brought into the second transmission state.

On the other hand, when switching between the first and second transmission states, the control device 100 controls the solenoid valves 365(1), 365(2), 367(1), and 367(2) to perform the Position control different from that in mode 3 is performed.

That is, at time Ta in FIG. 15, when it is recognized that the shift operation member 90 has been operated from the zero speed position side to the switching speed position (that is, based on the signal from the output sensor 95b, the speed change output shaft 45 is shifted). When it recognizes that the rotation speed has reached the switching speed from the state below the switching speed, the control device 100 is positioned at the supply position at the time before the transmission state switching (in this example, at the time of the first transmission state). The input side first solenoid valve 365(1) and the output side first solenoid valve 367(1), which had been at the discharge position before switching, are maintained at the supply position. The second 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 engagement oil pressure, and the input side second supply/discharge line 360(2) is maintained. And the hydraulic pressure of the output side second supply/discharge line 362(2) gradually rises and reaches the engagement hydraulic pressure at time Tb.

Here, the control device 100 is supplied with pressure oil via the second input side solenoid valve 365(2) and the second output side solenoid valve 367(2) that have been moved from the discharge position to the supply position. a pressure sensor 370(2) corresponding to the fact that the hydraulic pressures of the input side second supply/discharge line 360(2) and the output side second supply/discharge line 362(2) have reached a switching hydraulic pressure P lower than the engagement hydraulic pressure; 372(2), the first input-side solenoid valve 365(1) and the first output-side solenoid valve 367(1), which were in the supply position before switching, are now in the supply position. to the ejection position.
The switching oil pressure P is set to a sliding engagement state in which the friction plates of the corresponding clutch mechanism slide to transmit power.

According to the transmission structure according to the present embodiment having such a configuration, it is possible to prevent, as much as possible, the occurrence of a state in which the driving force is not transmitted to the drive wheels 220 when switching between the first and second transmission states. is reduced, and 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 first element when the rotation speed of the second element due to the rotational power transmitted via the transmission mechanism 50(2) becomes the same, and the HST output is set to the second HST speed in the second transmission state. The rotation speed is set to be the same as the rotation speed of the first element due to the rotational power transmitted through the input side first transmission mechanism 50(1) in the first transmission state.

Theoretically, therefore, no rotational speed difference occurs in the first element and/or the second element when switching between the first and second transmission states.
However, due to manufacturing errors or the like, a rotational speed difference may occur in 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 a rotational speed difference occurs in the first element and/or the second element at the time of switching between the first and second transmission states, the first and second transmission states The clutch mechanism (in the example of FIG. 15, , the friction plates of the input-side second clutch mechanism 60 (2)) slip and gradually frictionally engage, the oil pressure of the clutch mechanism reaches the engagement oil pressure, and the clutch mechanism enters the fully engaged state. immediately before the first and second transmission states are switched, the clutch mechanism (in the example of FIG. 15, the input-side first clutch mechanism 60(1)) is released from the engagement hydraulic pressure. be done.

Therefore, it is possible to prevent or reduce as much as possible the occurrence of a state in which the driving force is not transmitted to the drive wheels 220 when switching between the first and second transmission states, and furthermore, the switching between the first and second transmission states is performed. It is possible to effectively prevent or reduce damage to the transmission system due to switching shocks and double transmission conditions that may sometimes occur.

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

Therefore, theoretically, no rotational speed difference occurs in the transmission output shaft 45 when switching between the first and second transmission states.
However, due to a manufacturing error or the like, a rotational speed difference may occur in the transmission 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 mechanism (in the example of FIG. 15, the second output side solenoid valve 367(2) in the example of FIG. 15) supplied with pressure oil via the solenoid valve (in the example of FIG. 15, the second output side solenoid valve 367(2)) moved to the supply position. The friction plates of the clutch mechanism 80 (2)) are gradually frictionally engaged while slipping, and immediately before the hydraulic pressure of the clutch mechanism reaches the engagement hydraulic pressure and the clutch mechanism becomes fully engaged, the first and The hydraulic pressure of the clutch mechanism (the output-side first clutch mechanism 80(1) in the example of FIG. 15) that was in the engaged state before switching to the second transmission state is released from the applied hydraulic pressure.

Therefore, it is possible to prevent or reduce as much as possible the occurrence of a state in which the driving force is not transmitted to the drive wheels 220 when switching between the first and second transmission states, and furthermore, the switching between the first and second transmission states is performed. It is possible to effectively prevent or reduce damage to the transmission system due to switching shocks and double transmission conditions that may sometimes occur.

At the time of switching between the first and second transmission states, the electromagnetic valves (in the example of FIG. 1 solenoid valve 367 (1)) is maintained at the supply position, and the solenoid valves (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 supply/discharge line (example in FIG. immediately before the hydraulic pressures of the input side second supply/discharge line 360(2) and the output side second supply/discharge line 362(2) reach the engaging hydraulic pressure and the clutch mechanism becomes fully engaged. , the solenoid valves (the first input-side solenoid valve 365(1) and the first output-side solenoid valve 367(1) in the example of FIG. 15), which were positioned at the supply position before switching, are moved from the supply position. The configuration for moving to the ejection position is the input side clutch mechanism formed by the input side first and second clutch mechanisms 60(1) and 60(2), which may cause rotational speed differences due to manufacturing errors and the like. Applies 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), 80(2), and the other has no or little possibility It is also possible to employ the dog clutch type shown in FIG. 10 to reduce the cost.

Embodiment 6
Hereinafter, still another embodiment 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 this embodiment.
In the drawings, the same members as in the above-described embodiment are denoted by the same reference numerals, and descriptions thereof are omitted as appropriate.

In the transmission structure 1 according to Embodiment 1, 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 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 and the rotational speed of the second element becomes the same, and the rotational 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 element in the first transmission state 1 transmission mechanism 50(1) and the rotation speed of the first element due to the rotational power transmitted via the transmission mechanism 50(1) are set to be the same. The side first gear ratio and the second gear ratio of the output side second transmission mechanism 70(2) are such that the rotation speed appearing on the speed change output shaft 45 when the HST output is set to the second HST speed is the first speed. and are set to be the same in the second transmission state.

According to the transmission structure 1 according to the first embodiment, theoretically, when switching between the first and second transmission states, the rotational speed of the first element and/or the second element and the shift output shaft 45 is increased. no difference occurs.

However, due to factors such as the number of teeth of the gears forming the input side first and second transmission mechanisms 50(1) and 50(2), the input side first and second gear ratios may be set to the ideal set values. may not be set.
In such a case, when switching between the first and second transmission states, a difference in rotational speed occurs in the first element and/or a difference in rotational speed occurs in the second element.

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

In view of this point, in the transmission structure 6 according to the present embodiment, when switching between the first and second transmission states, the first element and/or the second element, and the speed change output shaft 45 have a rotational speed difference. When this occurs, the switching shock caused by the rotational speed difference and damage to the transmission system due to the double transmission state 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 ( 1) and 50(2) are replaced with input side first and second transmission mechanisms 650(1) and 650(2), and the output side first and second transmission mechanisms 70(1) and 70 It has output side first and second transmission mechanisms 670(1) and 670(2) in place of (2).

As shown in FIG. 16, the input-side first transmission mechanism 650(1) includes 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). and an input-side first driven gear 654(1) meshed with the driving gear 652(1) and connected to the first element.

The second input-side transmission mechanism 650(2) includes a second input-side drive gear 652(2) supported relatively rotatably on the main drive shaft 212, and a second input-side drive gear 652(2). and an input side second driven gear 654(2) meshed and connected to the second element.

The first output-side transmission mechanism 670(1) is connected to a first output-side driving gear 672(1) supported by the transmission intermediate shaft 43 so as not to rotate relative to the first output-side driving gear 672(1). and an output-side first driven gear 674(1) which is meshed with 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 driving gear 672(2) connected to the first element and the output-side second driving gear 672(2), and an output-side second driven gear 674(2) supported by 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) at the time of switching from the first transmission state to the second transmission state.

In this embodiment, when switching between the first and second transmission states, the control device 100 controls the solenoid valves 365(1), 365(2), 367(1), and 367(2). , the same position control as in the fifth embodiment is performed.

17, based on the signal from the output sensor 95b, the controller 100 recognizes that the rotation speed of the speed change output shaft 45 has reached the switching speed from the state below the switching speed. The first input-side solenoid valve 365(1) and the first output-side solenoid valve 367(1), which were positioned at the supply position at the time before switching (at the time of the first transmission state in this example), are moved to the supply position. , the input-side second solenoid valve 365 (2) and the output-side second solenoid valve 367 (2), which were positioned at the discharge position before switching, are moved from the discharge position to the supply position. .

As a result, as shown in FIG. 17, the first input side supply/discharge line 360(1) and the first output side supply/discharge line 362(1) are maintained at the engagement oil pressure, and the second input side supply/discharge line 360(1) is maintained at the engagement hydraulic pressure. 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 is supplied with pressure oil via the second input side solenoid valve 365(2) and the second output side solenoid valve 367(2) that have been moved from the discharge position to the supply position. a pressure sensor 370(2) corresponding to the fact that the hydraulic pressures of the input side second supply/discharge line 360(2) and the output side second supply/discharge line 362(2) have reached a switching hydraulic pressure P lower than the engagement hydraulic pressure; 372(2), the first input-side solenoid valve 365(1) and the first output-side solenoid valve 367(1), which were in the supply position before switching, are now in the supply position. to the ejection position.

According to the transmission structure 6 having such a configuration, if a rotational speed difference 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, the solenoid valves (in the example of FIG. 17, the input side second solenoid valve 365 (2) and the output side second solenoid valve 367(2)) to which pressure oil is supplied (in the example of FIG. 17, the input-side second clutch mechanism 60(2) and the output-side second clutch mechanism 80(2)). The groups are gradually frictionally engaged while slipping, and are engaged immediately before the hydraulic pressure of the clutch mechanism reaches the engagement hydraulic pressure and the clutch mechanism becomes fully engaged, and before switching between the first and second transmission states. The clutch mechanisms (in the example of FIG. 17, the input-side first clutch mechanism 60(1) and the output-side first clutch mechanism 80(1)) are released from the applied hydraulic pressure.

Therefore, it is possible to prevent or reduce as much as possible the occurrence of a state in which the driving force is not transmitted to the drive wheels 220 when switching between the first and second transmission states, and furthermore, the switching between the first and second transmission states is performed. It is possible to effectively prevent or reduce switching shocks and damage to the transmission system that may sometimes occur.

In the present embodiment, when switching between the first and second transmission states, one of the solenoid valves, which was positioned at the supply position at the time before switching, is maintained at the supply position at the time before switching. The other solenoid valve, which has been positioned at the discharge position in , is moved from the discharge position to the supply position, and the hydraulic pressure of the supply/discharge line supplied with pressurized oil via the other solenoid valve changes to the switching hydraulic pressure P, which is lower than the engagement hydraulic pressure. The input-side first and second clutch mechanisms 60(1), 60(1), 60(2) and the output side clutch unit formed by the output side first and second clutch mechanisms 80(1), 80(2). Of course, the present invention is not limited to such a form, and the above configuration may be the input side clutch unit on the side where the rotation speed difference occurs due to the setting of the number of teeth of the gears constituting the transmission mechanism. And it is also possible to apply it to only one of the output side clutch units and to reduce the cost by adopting the dog clutch type shown in FIG.

Moreover, it is also possible to apply the present embodiment to the transmission structure 2 according to the second embodiment.

In Embodiments 5 and 6, when switching between the first and second transmission states, the hydraulic pressure of the clutch mechanism that was in the engaged state before switching (hereinafter referred to as the pre-switching engagement clutch mechanism) is applied. Although the combined oil pressure is lowered at a substantially constant rate and released, instead of this, as shown in FIG. ) reaches the switching hydraulic pressure P, the hydraulic pressure of the pre-switching engagement clutch mechanism is lowered at a substantially constant rate, and when the hydraulic pressure of the pre-switching disconnect clutch mechanism reaches the engagement hydraulic pressure, switching It is also possible to reduce the time of unnecessary slip transmission state by lowering the oil pressure of the front engagement clutch mechanism to the release oil pressure at once, thereby improving the durability of the friction plates.

In the fifth and sixth embodiments, the pressure sensors 370(1), 370(2), 372(1), and 372(2) are configured to detect the engagement state of the corresponding friction plate clutch mechanism. Instead, the corresponding friction is detected 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), 367(2). It is also possible to employ a configuration that detects the engagement state of the plate-type clutch mechanism.

Embodiment 7
Hereinafter, still another embodiment of the transmission structure according to the present invention will be described with reference to the accompanying drawings.
FIG. 19 shows a transmission schematic diagram of a 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 this embodiment.
In the drawings, the same members as in the above-described embodiment are denoted by the same reference numerals, and descriptions thereof are omitted as appropriate.

The transmission structure 1 according to the first embodiment is configured such that normal/reverse switching of driving force is performed by the forward/rearward switching mechanism 230 arranged downstream of the transmission output shaft 45 in the transmission direction.

That is, as shown in FIG. 1 , the transmission structure 1 according to the first embodiment includes the speed change output shaft 45 and the travel transmission shaft 235 that is operatively rotationally driven by the rotational power of the speed change output shaft 45 . Between them, there is the forward/reverse switching mechanism 230 that switches the direction of rotation of the driving force between the forward direction and the reverse direction.

On the other hand, in the transmission structure 7 according to the present embodiment, the rotational direction of the driving force transmitted to the speed change output shaft 45 can be switched between normal and reverse.

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

The reverse transmission mechanism 70 (R) includes a reverse drive gear 72 (R) supported non-rotatably on the transmission intermediate shaft 43 and a reverse driven gear 74 (R) supported relatively rotatably on the transmission output shaft 45 ( R), and a reverse idle gear 73(R) meshed with the reverse driving gear 72(R) and the reverse driven gear 74(R).

The reverse clutch mechanism 80(R) includes a reverse clutch housing 82(R) supported by the transmission output shaft 45 so as not to relatively rotate, and a reverse drive mechanism supported by the reverse driven gear 74(R) so as not to relatively rotate. 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 face the reverse drive side friction plates and the reverse drive side friction plates so as not to relatively rotate; and a reverse piston (not shown) that frictionally engages the reverse friction plate group 84(R).

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

The control device 100 is
When the shift operating member 90 is positioned between the zero speed position and the switching speed position (that is, the rotation speed of the shift output shaft 45 is determined based on the detection signals of the HST sensor 95a and the output sensor 95b) is in a low speed state from zero speed to less than switching speed in the forward direction), the forward first clutch mechanism 60(1) and the first output clutch mechanism 80(1) are engaged. 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, and
In a state in which the speed change operation member 90 is operated from the zero speed position to the reverse side (that is, in a reverse transmission state in which the rotational speed of the speed change output shaft 45 changes from zero speed to the reverse side), the input A reverse transmission state is produced in which the side first clutch mechanism 60(1) and the reverse clutch mechanism 80(R) are engaged.

FIG. 21 shows a graph representing the relationship between the traveling vehicle speed and the HST output in work vehicle 202 to which transmission structure 7 according to the present embodiment is applied.
21(a) and 21(b) are graphs showing a 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 first forward transmission state, the control device 100 shifts the HST output from the first HST speed to the second HST speed according to the forward speed increasing operation of the shift operating member 90. The output adjusting member 20 is operated as follows.

That is, when the gear shift operation member 90 is operated between the zero speed position and the forward side switching speed position, the control device 100 causes the forward first transmission state to appear, and then performs the gear shift operation. The output adjusting member 20 is actuated 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 second forward transmission state, the control device 100 controls the output adjusting member 20 so that the HST output shifts from the second HST speed to the first HST speed in accordance with the forward speed increasing operation of the speed change operation member 90 . to activate.

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

That is, when the gear shift operating member 90 is operated from the zero speed position to the reverse side, the control device 100 causes the reverse transmission state to appear, and then the gear shift operating member 90 is operated to accelerate backward. The output adjusting member 20 is operated so that the HST output shifts from the side of the first HST to the side of the second HST as the speed increases.

As shown in FIG. 21, also in the present embodiment, as in the first embodiment, when switching between the forward-side first and second transmission states, the traveling speed (that is, the shift output shaft 45) has a speed difference. It is configured so that it does not occur.

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) are the rotation speed of the second element when the HST output is set to the second HST speed in the forward first transmission state and the transmission through the input side second transmission mechanism 50 (2) in the forward second transmission state. When the rotational speed of the second element is the same as that of the second element due to the rotational power applied, and the HST output is set to the second HST speed in the second forward transmission state, the rotational speed of the first element and the first forward transmission state are different. The rotational speed of the first element is set to be the same as the rotational speed of the first element due to the rotational power transmitted via the input side first transmission mechanism 50(1).

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 rotation speed appearing on the speed change output shaft 45 is the same in the first and second transmission states when the HST output is set to the second HST speed. ing.

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

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 rotation speed of the second element is set to zero speed. A gear mechanism 30 is set.
According to such a configuration, switching between forward and backward travel of the vehicle can be performed without difficulty. In particular, this configuration is effective in the case of a working vehicle that performs work that requires frequent forward/reverse switching.

Next, a pressurized 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), the Output side first supply/discharge line 362(1) (advance side first supply/discharge line), output side second supply/discharge line 362(2) (advance side second supply/discharge line), and reverse clutch mechanism 80 (R), a forward supply line 310 (F), a reverse supply line 310 (R), and the input side first solenoid valve 365 (1). , the second input side solenoid valve 365(2), the first output side solenoid valve 367(1) and the second output side solenoid valve 367(2), the first input side pressure sensor 370(1), 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 is provided with an interposed check valve 320 , a pilot valve 330 interposed in the reverse supply line 310 (R), the drain line 157 , and a forward/reverse switching electromagnetic valve 300 .

In this embodiment, the first input side solenoid valve 365(1), the second input side solenoid valve 365(2), the first output side solenoid valve 367(1) and the second output side solenoid valve 367(2) is 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. 362(1) (advance-side first supply/discharge line) and the output-side second supply/discharge line 362(2) (advance-side second supply/discharge line). When positioned, it drains the corresponding supply/drain line 360(1), 360(2), 362(1), 362(2), while when positioned in the supply position, the corresponding supply/drain line 360(1) is drained. , 360(2), 362(1), 362(2) are fluidly connected to the forward supply line 310(F).

The forward/reverse switching solenoid valve 300 is position-controlled by the control device 100, fluidly connects the forward supply line 310(F) to the pressure oil supply line 155, and connects the reverse supply line 310(R) to the pressure oil supply line 155. a forward position F fluidly connected to the drain line 157; and a neutral position N in which the pressure oil supply line 155, the forward feed line 310(F) and the reverse feed line 310(R) are fluidly connected to the drain line 157. ing.

The check valve 320 directs pressure oil supplied from the forward drive supply line 310(F) through the input side first electromagnetic valve 365(1) to the input side first clutch mechanism 60(1). It is interposed in the first input-side supply/discharge line 360(1) so as to allow flow in the pressure oil supply direction and prevent flow in the pressure oil discharge direction in the opposite direction.

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

The pilot valve 330 has a communicating position that communicates the supply line 310(R) for reverse movement, and a reverse position while allowing pressure oil in the supply line 310(R) for reverse movement to flow in the pressure oil supply direction. and a non-return position that prevents flow.

The pilot valve 330 is urged toward the communication position by an urging member 332, and the hydraulic pressure of the forward supply line 310(F) is used as the pilot pressure. is supplied, the urging force of the urging member 332 is resisted and positioned at the non-return position.

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

The pressurized oil supply and discharge arrangement 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/reverse switching electromagnetic 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), the output side second supply/discharge line The exhaust line 362(2) and the backward supply/exhaust line 364 are all opened, and all the clutch mechanisms 60(1), 60(2), 80(1), 80(2), 80(R) are in the disconnected state. As a result, power is not transmitted to the speed change output shaft 45 .

When the shift operating member 90 is operated forward, the control device 100 positions the forward/reverse switching solenoid valve 300 at the forward position F before the HST 10 outputs 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 non-return position by the hydraulic pressure of the forward supply line 310(F). Therefore, the input-side first supply/discharge line 360(1) is in a state where the hydraulic pressure is maintained.

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

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

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 electromagnetic valves 365(2) and 367(2), The reverse supply/discharge line 364 is drained through the reverse supply supply line 310 (R) and the forward/rearward switching solenoid valve 300 .

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

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

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

When the shift operating member 90 is operated to the reverse side, the control device 100 positions the forward/reverse switching solenoid valve 300 to the reverse position R before the HST 10 outputs the first HST speed.

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

At this time, the first input side solenoid valve 365(1), the second input side solenoid valve 365(2), the first output side solenoid valve 367(1) and the second output side solenoid valve 367(2) are all positioned in the ejection 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 connected to the corresponding electromagnetic valves 365(2). , 367(1), 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 of the check valve 320 in the pressure oil supply direction.
Therefore, although the first input-side solenoid valve 365(1) is positioned at the discharge position, the first input-side supply/discharge line 360(1) is pressurized through the reverse supply line 310(R). Oil is supplied and the first input clutch mechanism 60(1) is engaged.

At this time, since the forward supply line 310(F) is open, the pilot valve 330, which uses the hydraulic pressure of the forward supply line 310(F) as a pilot pressure, does not move the biasing member 332. It is positioned at the communicating position by the biasing force.
Therefore, pressure oil is effectively supplied to the input-side first supply/discharge line 360(1) through 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 of the pilot valve 300 in the pressure oil supply direction. ) is supplied with pressurized oil.
As a result, a reverse transmission state appears in which the first input side clutch mechanism 60(1) is engaged and the reverse clutch mechanism 80(R) is engaged.

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 between the forward drive side first and second transmission states, and the output side first solenoid valve 365(1) and the output side first solenoid valve 365(2). Regarding the switching control timing of the solenoid valve 367(1) and the output side second solenoid valve 367(2), the switching control timings of the various embodiments such as the third embodiment, the fifth embodiment, and the sixth embodiment are described. 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), 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 operated friction plate types.

Alternatively, at least one of an input-side clutch unit formed by the input-side first and second clutch mechanisms and an output-side clutch unit formed by the output-side first and second clutch mechanisms may be It is also possible to use a dog clutch type in form 4.

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

In the transmission structure 7B, in place of the friction plate type first and second input side clutch mechanisms 60(1) and 60(2), the dog clutch type It has an input side clutch unit 410 .

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

Embodiment 8
Hereinafter, still another embodiment of the transmission structure according to the present invention will be described with reference to the attached drawings.
FIG. 23 shows a transmission schematic diagram of a working vehicle 203 to which the transmission structure 8 according to the present embodiment is applied.
24 shows a partial longitudinal side view of the working vehicle 203. As shown in FIG.
In the drawings, the same members as in the above-described embodiment are denoted by the same reference numerals, and descriptions thereof are omitted as appropriate.

As shown in FIG. 23, the transmission structure 8 according to the present embodiment further includes an output side third transmission mechanism 70 (3) and an output side and 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) and 50(2), and the input side First and second clutch mechanisms 60(1), 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 shift operation member 90, the HST sensor 95a, the output sensor 95b, and the control device 100.
In this 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) transmits the rotational power of the first element (in this embodiment, the internal gear 36) to the output-side second transmission mechanism 70(2). Operation can be transmitted to the speed change output shaft 45 at an output side third speed ratio that rotates the speed change output shaft 45 at a higher speed than the speed 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 representing the relationship between the traveling vehicle speed and the HST output in work vehicle 203 to which transmission structure 8 according to the present embodiment is applied.

As shown in FIG. 25, in the present embodiment, the control device 100
When the shift operating member 90 is positioned between the zero speed position and the first switching speed position (that is, when the shift output shaft 45 is shifted 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 in the engaged state and the input side second clutch mechanism 60(2) is in the disengaged state. a 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 disengaged to appear,
When the shift operating member 90 is positioned between the first switching speed position and the second switching speed position (that is, when the shift output shaft is detected based on the detection signals of the HST sensor 95a and the output sensor 95b) 45 is in an intermediate speed state from the first switching speed to the second switching speed), the input side first clutch mechanism 60(1) is in the disengaged state and the input side second clutch mechanism 60(2) is switched. is engaged, the output-side second clutch mechanism 80(2) is engaged, and the remaining output-side first and third clutch mechanisms 80(1), 80(3) are disengaged. manifest a second dynamic state,
In a state where 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 set to the second speed 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 third output-side clutch is engaged while disengaging the first input-side clutch mechanism 60(1) and engaging the second input-side clutch mechanism 60(2). A third transmission state appears in which the mechanism 80(3) is in the engaged state and the remaining output side first and second clutch mechanisms 80(1) and 80(2) are in the disengaged state.

As shown in FIG. 23, the transmission structure 8 has the forward/reverse switching mechanism 230 interposed between the transmission output shaft 45 and the traveling transmission shaft 235. The output of 230 is transmitted to a travel transmission shaft 235 .

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

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 is performed. When the member 90 is positioned at the forward-side first switching speed position, the traveling transmission shaft 235 rotates at a rotation speed that makes the traveling vehicle speed +a.

When the gear shift operating 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 gear shift operating member 90 is shifted to 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 rotation speed that causes the traveling vehicle speed to be +b.

When the shift operating member 90 is operated beyond the forward second switching speed position, the forward third transmission state appears, and the shift operating member 90 is positioned at the forward maximum speed position. At this point, the traveling transmission shaft 235 rotates at a rotation speed that makes the traveling vehicle speed +c.

Similarly, when the gear shift operating member 90 is operated between the zero speed position and the reverse first switching speed position, the reverse first transmission state appears, and the gear shift operating member 90 is shifted to the reverse first switching speed position. When it is positioned at the first switching speed position, the traveling transmission shaft 235 rotates at a rotation speed that makes the traveling vehicle speed -a.

When the gear shift operating member 90 is operated between the reverse first switching speed position and the second reverse gear switching position, the second reverse transmission state appears, and the gear shift operating member 90 is shifted to the reverse travel side. When the traveling transmission shaft 235 is positioned at the second switching speed position, the traveling transmission shaft 235 rotates at a rotation speed that makes the traveling vehicle speed -b.

When the gear shift operating member 90 is operated beyond the reverse second switching speed position, the third reverse transmission state appears, and the gear shift operating member 90 is positioned at the maximum reverse speed position. At this point, the traveling transmission shaft 235 rotates at a rotation 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 this 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 embodiment In the form of , the rotational speed of the internal gear 36) and the rotational speed of the first element due to the rotational power transmitted through the input side first transmission mechanism 50 (2) in the first transmission state are are 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 speed appearing on the shift output shaft 45 is set to be the same in the first and second transmission states.

Furthermore, as shown in FIG. 25, in the transmission structure 8 according to the present embodiment, when switching between the second and third transmission states, the control device 100 controls the shift output shaft 45 in the transmission state after switching. The output adjustment member 20 is actuated so that the rotation speed appearing at 1 is equal to or close to the rotation speed appearing at the transmission 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 under the second transmission state and reaches the second switching speed position (when the rotational 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 rotates the speed change output shaft 45 at the second switching speed under the second transmission state (first HST speed) to rotate the speed change output shaft 45 at the second switching speed or speed under the third transmission state. The output adjusting member 20 is actuated so as to shift to a rotational speed (third HST speed in FIG. 25) that rotates at a speed close to that speed.

Further, when the speed change operation member 90 is operated in the deceleration direction under the third transmission state and reaches the second switching speed position (when the rotational speed of the speed change output shaft 45 reaches the second switching speed), the control device 100 shifts the output side third clutch mechanism 80(3) from the engaged state to the disengaged state and the output side second clutch mechanism 80(2) from the disengaged state to the engaged state, while the HST 10 changes from the rotation speed (third HST speed) at which the speed change output shaft 45 rotates at the second switching speed under the third transmission state to the speed change output shaft 45 at the second switching speed or the same under the second transmission state. The output adjustment member 20 is actuated so as to shift to a rotation speed (first HST speed) that rotates in the vicinity.

According to the transmission structure 8 having such a configuration, it is possible to expand the shiftable range (shift range) while obtaining the same effects 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 rotation speed appearing on the shift output shaft 45 is set to be the same in the first and second transmission states. Although the first and second gear ratios on the output side are set, instead of this, when switching between the first and second transmission states, the transmission output shaft 45 appears in the transmission state after switching. The control device 100 may operate the output adjusting member 20 so that the rotational speed of the output shaft 45 coincides with or approaches the rotational speed appearing on the transmission 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 includes the transmission intermediate member connected to the second element (the carrier 38 in the present embodiment) so as not to rotate relative to the axis. A transmission transmission shaft 44 is fitted around the shaft 43 so as to be relatively rotatable.

The transmission transmission shaft 44 is connected to the first element (in this embodiment, the internal gear 36) so as not to rotate relative to the axis. The rotational power of the main drive shaft 212 is transmitted to the first element through the speed change transmission shaft 44, and the output side first and second transmission mechanisms 70(1) and 70(2) are connected to the speed change transmission shaft. 44 to transmit the rotational power of the first element to the speed change output shaft 45 .

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 connected to the main drive shaft 212. is supported so as not to rotate relative to the speed change transmission shaft 44 while being operatively connected to the input side first driving gear 52(1) supported so as to rotate relative to the transmission shaft 44.

In addition, the output-side second drive gear 72(2) of the output-side second transmission mechanism 70(2) is connected to the output-side second driven gear 74(2) while the speed change transmission shaft 44 is driven. supported so as not to rotate relative to

The third output-side transmission mechanism 70(3) includes a third output-side drive gear 72(3) supported by the speed change transmission shaft 44 so as not to rotate relatively, and a third output-side drive gear 72(3). and an output side third driven gear 74(3) which is operatively connected and supported by the speed change output shaft 45 so as to be relatively rotatable.

The input side second transmission mechanism 50(2) is connected to the input side second driving gear 52(2) supported relatively rotatably on the main drive shaft 212, as in the first embodiment. , and the input-side first driven gear 54(2) which is operatively connected to the input-side second drive gear 52(2) and which is rendered non-rotatable 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 this embodiment) acting as the variable input portion so as not to rotate 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 supports a driven gear 216b of the gear train 216 for operatively connecting the rotational power of the motor shaft 16 to the third element (the sun gear 32) so as not to rotate relative to the driven gear 216b.

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 relatively rotate, and the output side third driven gear 74(3). ), a third drive-side friction plate supported non-relatively rotatably by ) and a third driven-side friction plate supported non-relatively-rotatably supported by the output-side clutch housing 83 in a state facing the third drive-side friction plate and a third output-side piston (not shown) that frictionally engages the third output-side friction plate group 84(3).

As shown in FIG. 24, the transmission structure 8 according to this embodiment is accommodated in the housing structure 500 of the working vehicle 203. As shown in FIG.

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 body 512, a front support wall 514 and a second support wall 518 extending radially inwardly from the inner surface of the front housing body 512 at an intermediate position in the front-rear direction, and A front bearing plate 516 is detachably connected to a boss projecting radially inward from the inner surface of the front housing body 512 near the rear opening.

The rear housing 550 includes a hollow rear housing main body 552 detachably connected to the front housing main body 512, and a boss portion protruding radially inward from the inner surface of the rear housing main body 552 in the vicinity of the front opening of the rear housing main body 552. and a rear support wall 556 extending radially inward from the inner surface of the rear housing body 552 at an intermediate position in the longitudinal direction.

In such a configuration, the main drive shaft 212 is supported by the front support wall 514, the front bearing plate 516 and the rear bearing plate 554 so as to be rotatable about the axis, and the input side first and second clutch mechanisms are supported. 60 ( 1 ), 60 ( 2 ) are supported on the main drive shaft 212 within the front housing body 512 . A receiving cylindrical portion 516a for supplying and discharging pressurized oil to and from the input side first and second clutch mechanisms 60(1) and 60(2) is formed integrally with the front bearing plate 516 externally fitted on the main drive shaft 212. ing. The input-side first and second supply/discharge lines 360(1) and 360(2) shown in FIG. 16 are connected to the receiving cylinder portion 516a using means such as pipes.

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

The transmission 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 speed change intermediate shaft 43 is supported by the front bearing plate 516 via the sun gear shaft 32a and the speed change input shaft 31 so as to be rotatable around the axis. is supported by the rear bearing plate 554 so as to be rotatable about its axis.

The hollow speed change transmission shaft 44 is fitted around the speed change intermediate shaft 43 so as to be relatively rotatable. It is supported by the front support wall 514 and the rear end side is supported by the front bearing plate 516 . The output side third drive gear 72(3) and the input side first driven gear 54(1) are disposed on the outer periphery of the intermediate portion of the transmission transmission shaft 44 from the internal gear 36 to the front bearing plate 516. ), and the output-side second drive gear 72(2) is spline-fitted.

The transmission output shaft 45 is supported by the second support wall 518, the rear bearing plate 554 and the rear support wall 556 so as to be rotatable about the axis. The first travel transmission shaft 235 is supported by the rear bearing plate 554 and the rear support wall 556 so as to be rotatable about the axis.

The speed change output shaft 45 has the output side third clutch mechanism 80(3) at the front end side, the output side first and second clutch mechanisms 80(1) and 80(2) at the intermediate portion, and the output side first and second clutch mechanisms 80(1) and 80(2) at the rear end side. support the clutch mechanism of the forward/reverse switching mechanism 230 respectively. The clutch mechanism of the forward/reverse switching mechanism 230 also uses a hydraulically operated friction plate clutch unit. A receiving cylindrical portion 556a for supplying and discharging pressurized oil to and from these five clutch mechanisms arranged on the speed change output shaft 45 is mounted on the rear support wall 556 and covered by the rear end portion of the speed change output shaft 45. is fitted.

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

In the present embodiment, the input side first and second clutch mechanisms 60(1), 60(2) and the output side first to third clutch mechanisms 80(1) to 80(3) are of the friction plate type, some or all of them may be of the dog clutch type.

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

Embodiment 9
Hereinafter, still another embodiment of the transmission structure according to the present invention will be described with reference to the accompanying drawings.
FIG. 27 shows a schematic diagram of transmission of a work vehicle 205 to which the transmission structure 9 according to this embodiment is applied.
28 shows a partial longitudinal side view of the working vehicle 205. As shown in FIG.
In the drawings, the same members as in the above-described embodiment are denoted by the same reference numerals, and descriptions thereof are 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 it includes the output side first to third clutch mechanisms 80(1) to 80(3). are doing.

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

That is, in the transmission structure 8 according to the eighth embodiment, the first to third transmissions appearing according to the respective engagement states of the output side first to third clutch mechanisms 80(1) to 80(3). Rotational power is transmitted to the travel transmission shaft 235 through the forward/reverse switching mechanism 230 in all states.

On the other hand, in the transmission structure 9 according to the present embodiment, the first and second clutch mechanisms appearing by the engagement states of the output side first and second clutch mechanisms 80(1) and 80(2), respectively. In the transmission state, while the rotational power is transmitted to the traveling transmission shaft via the forward/reverse switching mechanism 230, the third transmission appears when the output side third clutch mechanism 80(3) is engaged. In the state, the rotational power in the forward direction is transmitted to the travel transmission shaft 235 without going through the forward/reverse switching mechanism 230 .

Specifically, as shown in FIG. 27, the transmission structure 9 transfers the rotational power of the HST 10, the planetary gear mechanism 30, and the drive source 210 to the first element (this embodiment) at the input side first gear ratio. In the form of , the input-side first transmission mechanism 750 (1) capable of transmitting operation to the internal gear 36) and the input-side second gear ratio operate to the second element (the carrier 38 in this embodiment) The input-side second transmission mechanism 750(2), the input-side first and second clutch mechanisms 60(1), 60(2), the shift output shaft 45 and the travel transmission shaft 235, the a forward/reverse switching mechanism 230; an 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 rotation of the first element. A second transmission mechanism 770 (2) on the output side capable of transmitting power to the speed change output shaft 45 at the second gear ratio on the output side, and the rotational power of the first element to the driving power transmission shaft 235 in the forward direction. the output side third transmission mechanism 770 (3), the output side first to third clutch mechanisms 80 (1) to 80 (3), the shift operating member 90, and the HST sensor 95a. , and the control device 100 .

As shown in FIGS. 27 and 28, the transmission structure 9 further includes the transmission intermediate shaft 43 non-rotatably connected to the second element (in this embodiment, the carrier 38). ing.
Further, the transmission structure 9 has an output sensor 95b that directly or indirectly detects the rotation speed of the travel transmission shaft 235. As shown in FIG.

The input-side first transmission mechanism 750(1) includes an input-side first drive gear 752(1) supported relatively rotatably on a main drive shaft 212 operatively connected to the drive source 210, and the transmission intermediate shaft. 43, the input side first drive gear 752 (1) and the input side first drive gear 752 (1) and the input side first drive gear 752 (1) operatively connected to the first element (in this embodiment, the internal gear 36). driven gear 754(1).

The input-side second transmission mechanism 750(2) is supported relatively non-rotatably by the input-side second drive gear 752(2) supported relatively rotatably on the main drive shaft 212 and the transmission intermediate shaft 43. 754(2) is operatively connected to the input-side second drive gear 752(2) in the state of being held, and the rotational power of the main drive shaft 212 is transferred to the transmission intermediate shaft 43. to the second element (the carrier 38 in this embodiment).

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

That is, in the present embodiment, the input side first clutch mechanism 60(1) includes the input side clutch housing 62 supported by the main drive shaft 212 so as not to rotate relative to the input side clutch housing 62, and the input side clutch housing 62. A first driving-side friction plate supported so as not to rotate relatively, and a first driven-side friction plate supported so as not to rotate relatively to the input-side first driving gear 752(1) while facing the first driving-side friction plate. A first input-side friction plate group 64(1) including friction plates and a first input-side piston (not shown) frictionally engaging the first input-side friction plate group 64(1). be done.

The input-side second clutch mechanism 60 (2) includes the input-side clutch housing 62, second drive-side friction plates supported by the input-side clutch housing 62 so as not to rotate relative to each other, and the second drive-side friction plates. A second input-side friction plate group 64(2) including a second driven-side friction plate supported by the second input-side drive gear 752(2) so as to face each other so as not to rotate relative to the input-side second drive gear 752(2); It is configured to have an input-side second piston (not shown) that frictionally engages 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 It is configured to be able to transmit the rotational power of two elements 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 ( 2) has an output side first driven gear 774(1) operatively connected to it.

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 transfer the rotational power of the first element to the It is constructed so as to be able to transmit operation 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 ( 1) has an output side second driven gear 774(2) operatively connected to it.

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

That is, in the present embodiment, the output side first clutch mechanism 80 ( 1 ) includes an output side clutch housing 82 supported by the speed change output shaft 45 so as not to rotate relatively, and the output side first driven gear 774 . (1) a first drive-side friction plate supported so as not to rotate relative to each other; It is configured to have an output side first friction plate group 84(1) including plates, and an output side first piston (not shown) that frictionally engages the output side first friction plate group 84(1).

The output side second clutch mechanism 80(2) includes the output side clutch housing 82, a second drive side friction plate supported so as not to rotate relative to the output side second driven gear 774(2), and the second drive side friction plate. A second output-side friction plate group 84(2) including second driven-side friction plates supported by the output-side clutch housing 82 so as to face the drive-side friction plates so as not to rotate relative to each other; and an output-side second piston (not shown) that frictionally engages the friction plate group.

The third output-side transmission mechanism 770(3) transmits the rotational power of the first element to the traveling transmission shaft via the second output-side transmission mechanism 770(2) and the forward/reverse switching mechanism 230 in the forward transmission state. The rotational power of the first element is transmitted to the traveling transmission shaft 235 through 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 traveling transmission shaft 235. The gear ratio is set so that the rotational speed of the travel transmission shaft 235 is high when the vehicle is moving.

In the present embodiment, the output-side third transmission mechanism 770(3) uses the output-side second driven gear 774(2) in the output-side second transmission mechanism 770(2) to It is configured to be able to transmit the rotational power of one element to the traveling transmission shaft 235 .

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

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

That is, in the present embodiment, the output side third clutch mechanism 80 (3) includes the output side clutch housing 83 supported by the travel transmission shaft 235 so as not to rotate relatively, and the output side third driven gear. A third drive-side friction plate supported by 774(3) so as not to rotate relatively, and a third driven-side friction plate supported by the output-side clutch housing 83 so as not to rotate relatively while facing the third drive-side friction plate. A third output-side friction plate group 84(3) including friction plates and a third output-side piston (not shown) frictionally engaging the third output-side friction plate group 84(3). It is

The output side third driven gear 774(3) can be operatively connected to the output side first driven gear 774(1) instead of the output side second driven gear 774(2).

That is, the first output side driven gear 774(1) in the first output side transmission mechanism 770(1) is used to transmit the rotational power of the first element to the travel transmission shaft 235. It is also possible to modify the output side third transmission mechanism 770(3).

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

As shown in FIG. 29, in the present embodiment, the control device 100
operating the output adjustment member 20 so that the HST output becomes the first HST speed that makes the combined rotational power of the planetary gear mechanism 30 zero in response to the operation of the shift operation member 90 to the zero speed position;
When the shift operating member 90 is operated in the forward low speed range from the zero speed position to the forward first switching speed position, the first input clutch mechanism 60(1) is engaged. and while disengaging the input side second clutch mechanism 60(2), engaging the first output side first clutch mechanism 80(1) and other output side clutch mechanisms 80(2), 80( 3) is cut off to cause the first element to act as an input portion for the reference power operatively transmitted from the drive source 210 and the second element to act as an output portion for the combined rotational power, The forward/reverse switching mechanism 230 is placed in the forward transmission state while the first transmission state in which the combined rotational power output from the second element is transmitted to the speed change output shaft 45 is realized, and the speed change operation member operating the output adjusting member 20 so that the HST output shifts from the first HST speed side to the second HST speed side in response to the speed increasing operation of 90;
When the speed change operation member 90 is operated in the forward intermediate speed range from the first forward switching speed position to the second forward switching speed position, the first input clutch mechanism 60 (1 ) is disengaged and the second input clutch mechanism 60(2) is engaged, the second output clutch mechanism 80(2) is engaged and the other output clutch mechanism 80(1) is engaged. ) and 80(3) are cut off to cause the second element to act as an input section for the reference power and the first element to act as an output section for the combined rotational power, and the output from the first element is The forward/reverse switching mechanism 230 is brought into the forward transmission state while the second transmission state in which the combined rotational power generated by the combined torque is transmitted to the speed change output shaft 45 is realized, and according to the speed increasing operation of the speed change operation member 90 operating the output adjusting member 20 so that the HST output shifts from the second HST speed side toward the first HST speed side,
When the shift operation member 90 is operated in the forward high speed range beyond the second forward switching speed position, the first input clutch mechanism 60(1) is disengaged and the second input clutch mechanism 60(1) is disengaged. While engaging the clutch mechanism 60(2), the third output side clutch mechanism 80(3) is engaged and the other output side clutch mechanisms 80(1) and 80(2) are disengaged. Thus, the second element acts as an input portion for the reference power and the first element acts as an output portion for the combined rotational power, and the combined rotational power output from the first element is applied to the output side third The HST output is increased in accordance with the speed increasing operation of the speed change operation member 90 while the third transmission state in which the driving force in the forward direction is transmitted to the traveling transmission shaft 235 via the transmission mechanism 770(3) is realized. operating the output adjusting member 20 so as to shift from the 2nd HST speed side to the 1st HST speed side;
When the speed change operation member 90 passes through the forward second switching speed position between the forward intermediate speed range and the forward high speed range, the traveling transmission shaft in the transmission state appearing immediately after passing operating the output adjustment member 20 so that the rotation speed of the travel output shaft 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 low speed range from the zero speed position to the first reverse speed switching position, the forward/reverse switching is performed while the first transmission state is produced. The mechanism 230 is set in a reverse transmission state, and the output adjustment member 20 is adjusted so that the HST output shifts from the first HST speed side to the second HST speed side in accordance with the speed increasing operation of the speed change operation member 90. operate,
When the speed change operation member 90 is operated in the reverse high speed range beyond the first reverse speed switching position, the forward/reverse switching mechanism 230 is brought into the reverse transmission state while the second transmission state is brought about. and 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 according to the speed increasing operation of the shift operating member 90 .

As in the first embodiment, the input-side first gear ratio of the input-side first transmission mechanism 750(1) and the input-side second gear ratio of the input-side second transmission mechanism 750(2) The rotation speed of the second element (the carrier 38 in this 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 ) becomes the same as the rotational speed of the second element due to the rotational power transmitted through the first element (in the present embodiment, , the rotational speed of the internal gear 36) and the rotational speed of the first element due to the rotational power transmitted through 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 output is set to the second HST speed, the rotation speed appearing on the speed change output shaft 45 is set to be the same in the first and second transmission states.

As described above, when the shift operation member 90 passes through the forward second switching speed position between the forward intermediate speed range and the forward high speed range, the control device 100 controls the current shift position immediately after passing. The output adjusting member 20 is adjusted so that the rotation speed of the travel transmission shaft 235 in the transmitted state is equal to or close to the rotation speed of the travel output shaft 235 in the transmitted state immediately before passing. activate.

That is, when the speed change operating member 90 is operated in the speed increasing direction in the forward intermediate speed range (second transmission state) to pass through the forward second switching speed position and enter the forward 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 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 rotation speed (first HST speed) at which the traveling vehicle speed is +b under the second transmission state to the third transmission state. , the output adjusting member 20 is operated so as to shift the speed to a rotation speed (third HST speed) that makes the running vehicle speed +b or its vicinity.

Further, when the speed change operating member 90 is operated in the deceleration direction in the forward high speed range (third transmission state) to pass through the forward second switching speed position and enter the forward intermediate speed range, the above-mentioned The control device 100 shifts the third output-side clutch mechanism 80(3) from the engaged state to the disengaged state, and shifts the second output-side 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 rotation speed (third HST speed) at which the traveling vehicle speed is +b under the third transmission state to the second transmission state. The output adjusting member 20 is actuated so as to shift the speed to a rotation speed (first HST speed) that makes the running vehicle speed +b or its vicinity.

According to the transmission structure 9 having such a configuration, it is possible to obtain the same effect as that of the transmission structure 1 according to the first embodiment, and to further expand the shiftable range (shift range) on the forward side.

In the present embodiment, as described above, the first and second gear ratios on the output side are adjusted so that the running vehicle speed is the same in the first and second transmission states when the HST output is set to the second HST speed. However, instead of this, at the time of switching between the first and second transmission states, the traveling vehicle speed in the transmission state after switching is made to match or approach the traveling vehicle speed in the transmission state before switching. In addition, it is also possible to configure the control device 100 to operate the output adjusting member 20 .

The transmission structure 9 according to this embodiment is housed in the housing structure 500B of the working vehicle 205. As shown in FIG.

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 a housing body 505B extending from the first bearing plate 516B. A second bearing plate 554B is detachably connected to the housing body 505B at a longitudinally spaced position and forms a partitioned space S between itself and the first bearing plate 516B.

In this 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 body 510B in the vicinity of the rear opening of the front housing body 510B. is detachably connected to a boss portion 551 provided on the inner surface of the rear housing body 550B in the vicinity of the front opening of the rear housing body 550B.

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

The input side first and second drive gears 752 ( 1 ), 752 ( 2 ) and the input side first and second clutch mechanisms 60 ( 1 ), 60 ( 2 ) are arranged with respect 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 within the partitioned space S. As shown in FIG.

The input-side first and second driven gears 754(1), 754(2) are located at the same axial positions as the input-side first and second drive gears 752(1), 752(2), respectively. In this state, the transmission intermediate shaft 43 is supported by a portion of the transmission intermediate shaft 43 that is positioned within the partitioned space S. As shown in FIG.

The output side first and second driven gears 774(1), 774(2) and the output side first and second clutch mechanisms 80(1), 80(2) are connected to the output side first and second driven gears 774(1), 774(2). Gears 774(1) and 774(2) are positioned axially at the same positions as the second and first driven gears 754(2) and 754(1) on the output side, respectively. With the 2-clutch mechanisms 80(1), 80(2) axially positioned between the input-side first and second driven gears 774(1), 774(2), the shift output shaft 45 is It is supported by the part located in the said division space S among them.

The output-side third driven gear 774(3) and the output-side third clutch mechanism 80(3) are configured such that the output-side third driven gear 774(3) is axially 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 axial direction, and the output side first and second clutch mechanisms 80(1) are positioned relative to the output side second driven gear 774(2). ) and 80(2), and is supported by a portion of the traveling transmission shaft 235 located in the partitioned space S. As shown in FIG.

The forward/reverse switching mechanism 230 is supported by a portion of the speed change output shaft 45 and the travel transmission shaft 235 positioned outside the partitioned space S. As shown in FIG.

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

As shown in FIG. 28, in the present embodiment, the forward drive gear 711F is mounted on the rear portion of the speed change output shaft 45 that extends rearward from the second bearing plate 554B so as not to rotate relative thereto. The reverse drive gear 711R is axially separated from the forward drive gear 711F and is supported by the rear portion of the shift output shaft 45 so as not to rotate relative to the forward drive gear 711F.

In this embodiment, the speed change output shaft 45 is positioned on the rear side of the first speed change output shaft 45a positioned on the front side, and is coaxial with the first speed change output shaft 45a so as not to rotate relative to the axis. A second transmission output shaft 45 b is connected thereto, said second transmission output shaft 45 b forming a rear portion of said transmission output shaft 45 .

The forward driven gear 712F is rotatably attached to a rear portion of the travel transmission shaft 235 extending rearward from the second bearing plate 554B at the same axial position as the forward drive gear 711F. supported by
The reverse driven gear 712R is rotatably supported on the rear portion of the travel transmission shaft 235 at the same axial position as the reverse drive gear 711R.

The forward and reverse clutch mechanisms 720F and 720R are supported on the rear portion of the traveling transmission shaft 235 while being positioned between the forward driven gear 712F and the reverse driven gear 712R in the axial direction. It is

In the present embodiment, the travel transmission shaft 235 is positioned on the rear side of the first travel transmission shaft 235a positioned on the front side, and is coaxial with the first travel transmission shaft 235a so as not to rotate relative to the axis. A second travel transmission shaft 235b is connected thereto, said second travel transmission shaft 235b forming a rear portion of said travel transmission shaft.

By providing such a housing structure, the transmission structure 9 according to the present embodiment can effectively reduce the number of used gears 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. 2 driven gear 774(2).

Alternatively, the output side third driven gear 774(3) is positioned at the same position as the output side first driven gear 774(1) with respect to the axial direction. ). In this case, the output side third clutch mechanism 80(3) is axially aligned with the output side first driven gear 774(1) as a reference. and the second clutch mechanisms 80(1), 80(2), and is supported by a portion of the traveling transmission shaft 235 located in the partitioned space S. As shown in FIG.

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

Hydraulic oil is supplied to the output side first and second clutch mechanisms 80(1) and 80(2) through the shift output shaft and the bearing portion of the shift output shaft in the first bearing plate 516B. A rotary joint 88 is provided for evacuation.

Further, the transfer cylinder portion 555 attached to the traveling transmission shaft and the second bearing plate has a clutch mechanism for 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 is provided for supplying and discharging hydraulic oil.

1 to 9 transmission structure 10 HST
12 pump shaft 16 motor shaft 20 output adjusting member 30 planetary gear mechanism 32 sun gear 36 internal gear 38 carrier 43 speed change intermediate shaft 44 speed change transmission shaft 45 speed change 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 gears 74(2), 774(2) Output side second driven gears 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 Shift 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) Second supply/discharge line 165 Switching valve 200 Work vehicle 210 Drive source 212 Main drive shaft 220 Drive wheel 230 Forward/reverse switching mechanism 240 Subtransmission mechanism 360(1) Input side first supply/discharge line 360(2) Input side second supply/discharge line 362 (1) output side first supply/discharge line 362 (2) output side second supply/discharge line 365 (1) input side first solenoid valve 365 (2) input side second 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 uneven engagement portion 412 (2) Second uneven engagement portion 432 Output-side slider 505B Housing main body 510, 510B Front housing main body 511 Boss portion 550, 550B Rear housing main body 551 Boss portions 516, 516B First bearing plates 554, 554B Second bearing plates

Claims (31)

an HST that continuously shifts the rotary power operatively input from the drive source to the pump shaft into the rotary power from at least the first HST speed to the second HST speed according to the operating position of the output adjusting member, and outputs the rotary power from the motor shaft; ,
a planetary gear mechanism having first to third elements, wherein the third element acts as an input for HST output;
a speed change output shaft;
an input-side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at an 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 for engaging and disengaging 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 speed change output shaft at an output-side first gear ratio;
an output-side second transmission mechanism capable of transmitting the rotational power of the first element to the speed change output shaft at an output-side second gear ratio;
an output-side first clutch mechanism and an output-side second clutch mechanism for engaging and disengaging power transmission of the output-side first transmission mechanism and the output-side second transmission mechanism, respectively;
a speed change 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 transmission output shaft;
a control device that controls the operation of the output adjusting member, the input-side first and second clutch mechanisms, and the output-side first and second clutch mechanisms;
The control device engages the input side and output side first clutch mechanisms based on the detection signals of the HST sensor and the output sensor when the rotation speed of the speed change output shaft is in a low speed state below a predetermined switching speed. state and disengaging the input side and output side second clutch mechanisms, the first element acts as an input portion of the reference power operatively transmitted from the drive source, and the second element is synthesized. The output adjusting member is adapted to shift the HST output from the first HST speed to the second HST speed in accordance with the speed-increasing operation of the speed-change operating member while developing the first transmission state acting as an output portion of 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 disengaged and the input side and output side second clutch mechanisms are engaged. By setting the engaged state, a second transmission state is created in which the first element acts as an output part and the second element acts as an input part of the reference power, and according to the speed increasing operation of the speed change operation member. operating the output adjusting member 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 rotational speed of the first element and the first transmission when the rotational speed of the second element due to the rotational power transmitted through is the same and the HST output is set to the second HST speed in the second transmission state is set to be the same as the rotational speed of the first element due to the rotational power transmitted via the input side first transmission mechanism in the state of
The first and second gear ratios on the output side are set so that when the HST output is set to the second HST speed, the rotation speed appearing on the gear shift output shaft is the same in the first and second transmission states. A transmission structure characterized by: an HST that continuously shifts the rotary power operatively input from the drive source to the pump shaft into the rotary power from at least the first HST speed to the second HST speed according to the operating position of the output adjusting member, and outputs the rotary power from the motor shaft; ,
a planetary gear mechanism having first to third elements, wherein the third element acts as an input for HST output;
a speed change output shaft;
an input-side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at an 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 for engaging and disengaging power transmission of the input-side first transmission mechanism and the input-side second transmission mechanism, respectively;
output-side first and second clutch mechanisms for engaging and disengaging power transmission from the second element and the first element to the transmission output shaft, respectively;
a speed change 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 transmission output shaft;
a control device that controls the operation of the output adjusting member, the input-side first and second clutch mechanisms, and the output-side first and second clutch mechanisms;
The control device engages the input side and output side first clutch mechanisms based on the detection signals of the HST sensor and the output sensor when the rotation speed of the speed change output shaft is in a low speed state below a predetermined switching speed. state and disengaging the input side and output side second clutch mechanisms, the first element acts as an input portion of the reference power operatively transmitted from the drive source, and the second element is synthesized. The output adjusting member is adapted to shift the HST output from the first HST speed to the second HST speed in accordance with the speed-increasing operation of the speed-change operating member while developing the first transmission state acting as an output portion of 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 disengaged and the input side and output side second clutch mechanisms are engaged. By setting the engaged state, a second transmission state is created in which the first element acts as an output part and the second element acts as an input part of the reference power, and according to the speed increasing operation of the speed change operation member. operating the output adjusting member 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 rotational speed of the first element and the first transmission when the rotational speed of the second element due to the rotational power transmitted through is the same and the HST output is set to the second HST speed in the second transmission state The transmission structure is set so as to be the same as the rotational speed of the first element due to the rotational power transmitted through the input side first transmission mechanism in the event of a state. At the time of switching between the first transmission state and the second transmission state, the control device is arranged such that the rotation speed appearing on the transmission output shaft in the transmission state after switching is the same as the rotation speed appearing on the transmission output shaft in the transmission state before switching. 3. A transmission structure according to claim 2, wherein said power adjusting member is actuated to match or approximate the rotational speed being produced. 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 engaged, and both the first and second clutch mechanisms on the output side are engaged. 4. A transmission structure according to any one of claims 1 to 3, characterized in that a double transmission state is exhibited. At least one of an input side clutch unit formed by the input side first and second clutch mechanisms and an output side clutch unit formed by the output side first and second clutch mechanisms is of a dog clutch type,
A dog clutch type clutch unit is supported by a corresponding rotary shaft so as to be non-rotatable and axially movable, and has a slider 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 second uneven engagement portion is disengaged from the corresponding uneven engagement portion, and the first uneven engagement portion corresponds to the corresponding uneven engagement portion. Only the first clutch mechanism is engaged by being engaged with the concave-convex engaging portion, and when the first clutch mechanism is positioned at the second position on the other side in the axial direction, the first concave-convex engaging portion engages the corresponding concave-convex engaging portion. On the other hand, only the second clutch mechanism is engaged by engaging the first uneven engagement portion with the corresponding uneven engagement portion while being disengaged, and the slider moves 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, whereby the first and second 5. The transmission structure according to claim 4, wherein both of the clutch mechanisms are in the engaged state. The first input-side transmission mechanism is operatively connected to a first input-side drive gear supported relatively rotatably on a main drive shaft operatively connected to the drive source, and operatively connected to the first input-side drive gear. An input-side first driven gear that is relatively non-rotatable as one element,
The second input-side transmission mechanism is operably connected to a second input-side drive gear supported by the main drive shaft so as to be relatively rotatable, and to the second input-side drive gear, and is non-rotatable relative to the second element. and an input side first driven gear,
The input side clutch unit is of a dog clutch type, and has an input side slider as the slider,
The input-side slider is supported by the main drive shaft between the input-side first and second drive gears so as to be non-rotatable relative to and axially movable. While the engaging portion is disengaged from the uneven engagement portion of the second input side drive gear, the first uneven engagement portion is engaged with the uneven engagement portion of the first input side drive gear. Thus, only the input-side first clutch mechanism is engaged, and when the first clutch mechanism on the input side is positioned at the second position, the first concave-convex engaging portion is disengaged from the concave-convex portion engaging portion of the input-side first drive gear. While being engaged, the second uneven engagement portion is engaged with the uneven engagement portion of the second input side drive gear, so that only the second input side clutch mechanism is brought into the engaged state and is placed in the intermediate position. position, the first and second uneven engagement portions are respectively engaged with the uneven engagement portions of the input side first and second drive gears, thereby engaging both the first and second clutch mechanisms. 6. A transmission structure according to claim 5, characterized in that it is engaged. comprising 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 transmission 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 by the speed change intermediate shaft so as not to rotate relative to the speed change intermediate shaft, and to the output side first drive gear, and is rotatable relative to the speed change output shaft. a supported output side first driven gear;
The output-side second transmission mechanism is operably connected to the output-side second drive gear that is non-rotatably connected to the first element, and to the output-side second drive gear, and is rotatable relative to the speed change output shaft. a supported output side second driven gear;
The output-side first and second clutch mechanisms are provided on the output-side first and second driven gears and between the output-side first and second driven gears. an output-side slider supported so as to be relatively non-rotatable and axially movable, and provided with first and second concave-convex engaging 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 engagement of the uneven engagement portion with the uneven engagement portion of the output side first driven gear, only the output side first clutch mechanism is brought into the engaged state, 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 the concave-convex engagement portion of the output side second driven gear. Only the output side second clutch mechanism is engaged by engaging with the portion, and when it is positioned at an intermediate position between the first position and the second position with respect to the axial direction, the first and second clutch mechanisms are engaged. The uneven engagement portions are engaged with the uneven engagement portions of the output side first and second drive gears, respectively, so that both the output side first and second clutch mechanisms are engaged. The transmission structure according to claim 1, wherein: 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 supplied with pressure oil to engage the clutch. It is a hydraulically operated friction plate type that creates a mated state,
The transmission structure includes a pressurized oil supply line for receiving pressurized oil from a hydraulic source, and first and second clutch mechanisms for supplying and discharging pressurized oil to and from the first and second clutch mechanisms in the hydraulically operated friction plate type clutch unit. A second supply/discharge line, and first and second electromagnetic valves inserted in the first and second supply/discharge lines, respectively, for determining a discharge position for draining the corresponding supply/discharge line and the corresponding supply/discharge line. First and second electromagnetic valves that can take a supply position for fluidly connecting to the pressure oil supply line, and clutch engagement detection means for detecting the engagement state of the first and second clutch mechanisms in the friction plate type clutch unit. prepared,
The control device positions the first solenoid valve at the supply position and positions the second solenoid valve at the discharge position when the rotational speed of the speed change output shaft is less than the switching speed in a low speed state, thereby causing the first transmission state. , and in a high-speed state where the rotation speed of the speed change output shaft is equal to or 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 achieve the second transmission state , and when switching between the first and second transmission states, the solenoid valve, which was positioned at the supply position before switching, remains at the supply position and is positioned at the discharge position at the time before switching. The electromagnetic valve that has been engaged is moved from the discharge position to the supply position, and the clutch engagement is performed by detecting that the clutch mechanism supplied with pressure oil via the electromagnetic valve moved from the discharge position to the supply position is in the engaged state. 5. The electromagnetic valve according to claim 4, wherein after a predetermined time has passed from the time of recognition based on the signal from the detection means, the solenoid valve, which was positioned at the supply position at the time before switching, is moved from the supply position to the discharge position. transmission structure. The first and second solenoid valves receive the hydraulic pressure of the corresponding supply/discharge line as pilot pressure, and engage the hydraulic pressure of the corresponding supply/discharge line in the state where the position signal to the supply position is input from the control device. 9. The transmission structure of claim 8, wherein the transmission structure is a proportional solenoid valve configured to maintain oil pressure. The input-side first and second clutch mechanisms are of a hydraulically operated friction plate type that receives pressure oil supply to create a clutch engagement state,
The transmission structure includes a pressurized oil supply line for receiving pressurized oil from a hydraulic source, and input-side first and second input-side supply/discharge lines for supplying and discharging pressurized oil to and from the input-side first and second clutch mechanisms, respectively. and the first and second supply/discharge lines on the input side, respectively, and has 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. input-side first and second solenoid valves, and clutch engagement detection means for detecting the engagement state of the input-side first and second clutch mechanisms,
The control device positions the first input-side electromagnetic valve at a supply position and positions the second input-side electromagnetic valve at a discharge position in a low speed state in which the rotation speed of the speed change output shaft is less than the switching speed. In a high-speed state where the rotation speed of the speed change output shaft is equal to or higher than the switching speed, the first input-side electromagnetic valve is positioned at the discharge position and the second input-side electromagnetic valve is positioned at the supply position. When switching the transmission state, the solenoid valve that was positioned at the discharge position before switching is moved from the discharge position to the supply position while maintaining the solenoid valve that was positioned at the supply position at the time before switching at the supply position. When it is recognized based on the signal from the clutch engagement detection means that the clutch mechanism supplied with pressure oil through the electromagnetic valve moved from the discharge position to the supply position is in the slipping engagement state. 4. The transmission structure according to any one of claims 1 to 3, wherein the solenoid valve, which was positioned at the supply position at the time before switching, is moved from the supply position to the discharge position. The output-side first and second clutch mechanisms are of a hydraulically operated friction plate type that receives pressurized oil supply to create a clutch engagement state,
The transmission structure includes a pressurized oil supply line for receiving pressurized oil from a hydraulic source, and output-side first and second output-side supply/discharge lines for supplying and discharging pressurized oil to and from the output-side first and second clutch mechanisms, respectively. and the first and second supply/discharge lines on the output side, respectively. output-side first and second solenoid valves, and clutch engagement detection means for detecting the engagement state of the output-side first and second clutch mechanisms,
The control device positions the first output-side solenoid valve at a supply position and positions the second output-side solenoid valve at a discharge position in a low speed state in which the rotation speed of the speed change output shaft is less than the switching speed. In a high-speed state where the rotation speed of the speed change output shaft is equal to or higher than the switching speed, the first output-side solenoid valve is positioned at the discharge position and the second output-side solenoid valve is positioned at the supply position. At the time of switching, moving the solenoid valve, which was positioned at the discharge position before switching, from the discharge position to the supply position, while maintaining the solenoid valve positioned at the supply position at the time before switching at the supply position, When it is recognized based on the signal from the clutch engagement detection means that the clutch mechanism supplied with pressurized oil through the electromagnetic valve moved from the discharge position to the supply position is in the slipping engagement state, before switching. 4. The transmission structure according to any one of claims 1 to 3, wherein the electromagnetic valve that has been in the supply position at the time of is moved from the supply position to the discharge position. 4. A transmission structure according to claim 1, wherein said second input side clutch mechanism and said second output side clutch mechanism are friction plate type clutch mechanisms. 13. A transmission structure according to claim 12, wherein said first input side clutch mechanism and said first output side clutch mechanism are friction plate type clutch mechanisms. a pressurized oil supply line whose upstream side is fluidly connected to a hydraulic source;
a drain line;
a first supply/discharge line for supplying/discharging pressure oil to/from the input-side and output-side first clutch mechanisms;
a second supply/discharge line for supplying/discharging pressure oil to/from the input side and output side second clutch mechanisms;
A switching valve whose position is controlled by the control device,
The switching valve has a first position in which 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 a second position fluidly connecting to a drain line and fluidly connecting said pressure oil supply/discharge line to said second supply/discharge line,
The input-side first and second clutch mechanisms and the output-side first and second clutch mechanisms are hydraulically actuated to engage the power transmission of the corresponding transmission mechanism by receiving pressurized oil supply. 14. The transmission structure according to claim 12 or 13, wherein A transmission structure inserted in a traveling system transmission path of a work vehicle,
an HST that continuously shifts the rotary power operatively input from the drive source to the pump shaft into the rotary power from at least the first HST speed to the second HST speed according to the operating position of the output adjusting member, and outputs the rotary power from the motor shaft; ,
a planetary gear mechanism having first to third elements, wherein the third element acts as an input for HST output;
a speed change output shaft;
a first input-side transmission mechanism and a second input-side 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 for engaging and disengaging power transmission of the input-side first transmission mechanism and the input-side second transmission mechanism, respectively;
output-side first and second clutch mechanisms for engaging and disengaging power transmission from the second element and the first element to the transmission output shaft, respectively;
a speed change 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 transmission output shaft;
a control device that controls the operation of 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 supplied with pressure oil to engage the clutch. It is a hydraulically operated friction plate type that creates a mated state,
The transmission structure further includes a pressurized oil supply line that receives pressurized oil from a hydraulic source;
first and second supply and discharge lines for supplying and discharging pressurized oil to and from the first and second clutch mechanisms in the hydraulically operated friction plate type clutch unit;
First and second solenoid valves interposed in the first and second supply/discharge lines, respectively, are located in discharge positions for draining the corresponding supply/discharge lines and for connecting the corresponding supply/discharge lines to the pressure oil supply line. first and second solenoid valves that can take supply positions for connection;
clutch engagement detection means for detecting engagement states of the first and second clutch mechanisms in a 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 output side first clutch mechanisms when the rotational speed of the speed change output shaft is less than a predetermined switching speed. and by disengaging the input-side and output-side second clutch mechanisms, the first element acts as an input portion for the reference power that is operatively transmitted from the drive source, and the second element rotates in synthetic rotation. The output adjustment member is operated so that the HST output shifts from the first HST speed to the second HST speed in accordance with the speed increasing operation of the speed change operation member while the first transmission state acting as a power output portion is produced. 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 disengaged and the input side and output side second clutch mechanisms are engaged. state, the first element acts as an output part and the second element acts as an input part of the reference power to create a second transmission state, and according to the speed increasing operation of the speed change operation member, The output adjusting member is actuated so that the HST output shifts from the second HST speed to the first HST speed, and furthermore, when switching between the first and second transmission states, it is positioned at the supply position before the switching. While one of the first and second solenoid valves is maintained at the supply position, the other of the first and second solenoid valves, which was positioned at the discharge position before switching, is moved from the discharge position to the supply position. and when it is recognized based on the signal from the clutch engagement detection means that the clutch mechanism supplied with pressure oil via the other solenoid valve is in the slipping engagement state, the one solenoid valve is supplied. A transmission structure characterized by switching between engagement and disengagement of first and second clutch mechanisms in a friction plate clutch unit by moving from a position to a discharge position. an HST that continuously shifts the rotary power operatively input from the drive source to the pump shaft into the rotary power from at least the first HST speed to the second HST speed according to the operating position of the output adjusting member, and outputs the rotary power from the motor shaft; ,
a planetary gear mechanism having first to third elements, the third element acting as an input portion for an HST output;
a speed change output shaft;
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 for engaging and disengaging power transmission of the input-side first and second transmission mechanisms, respectively;
a first forward transmission mechanism and a second forward transmission mechanism capable of transmitting the rotational power of the second element and the first element to the speed change output shaft in a forward rotation state, respectively;
a reverse transmission mechanism capable of transmitting the rotational power of the second element to the speed change output shaft in a reversed state;
a forward first clutch mechanism, a forward second clutch mechanism, and a reverse clutch mechanism for engaging and disengaging power transmission of the forward first transmission mechanism, the forward second transmission mechanism, and the reverse transmission mechanism, respectively;
a speed change 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 transmission output shaft;
a control device that controls the operation of 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 reverse clutch mechanism;
Based on the detection signals of the HST sensor and the output sensor, the control device controls the input side first clutch mechanism and The HST output shifts from the first HST speed to the second HST speed in accordance with the forward speed increasing operation of the speed change operation member while the first forward transmission state in which the first forward clutch mechanism is engaged is realized. and the input-side second clutch mechanism and the forward second clutch mechanism are engaged when the rotational speed of the transmission output shaft is higher than the switching speed in the forward direction. operating the output adjusting member so that the HST output shifts from the first HST speed toward the second HST speed in accordance with the forward side speed increasing operation of the speed change operation member, In a 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 input side clutch mechanism and the reverse clutch mechanism are engaged is realized, and the A transmission structure, wherein 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 a reverse speed increasing operation of a shift operating member. The first input-side transmission mechanism transmits the rotational power of a drive source to the first element at an input-side first gear ratio, and the second input-side transmission mechanism transmits the rotational power of the drive source to a second input-side gear ratio. transmitting the operation to the second element at a gear ratio;
The input-side first and second gear ratios are determined by the rotation 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 first element when the rotational speed of the second element due to the rotational power transmitted through the transmission mechanism is the same, and the HST output is set to the second HST speed in the forward second transmission state. 16 , wherein the rotational speed of the first element is set to be the same as the rotational speed of the first element due to the rotational power transmitted through the input side first transmission mechanism in the first forward transmission state. transmission structure described in . The first forward transmission mechanism transmits the rotational power of the second element to the transmission output shaft at a first forward gear ratio, and the second forward transmission mechanism transmits the rotational power of the first element to the second forward gear ratio. transmitting an operation to the speed change output shaft at a speed ratio;
The forward first and second gear ratios are set so that when the HST output is set to the second HST speed, the rotational speeds appearing on the shift output shaft are the same in the first and second transmission states. 18. Transmission structure according to claim 16 or 17, characterized in that The HST and the planetary gear mechanism are set so that the rotation speed of the second element becomes zero speed when the HST output is set to the first HST speed in the engaged state of the first input side clutch mechanism. 19. A transmission structure as claimed in any one of claims 16 to 18, characterized in that a an HST that continuously shifts the rotary power operatively input from the drive source to the pump shaft into the rotary power from at least the first HST speed to the second HST speed according to the operating position of the output adjusting member, and outputs the rotary power from the motor shaft; ,
a planetary gear mechanism having first to third elements, wherein the third element acts as an input for HST output;
a speed change output shaft;
an input-side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at an 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 for engaging and disengaging 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 speed change output shaft at an output-side first gear ratio;
an output-side second transmission mechanism capable of transmitting the rotational power of the first element to the speed change output shaft at an output-side second gear ratio;
a third output-side transmission mechanism capable of transmitting the rotational power of the first element to the speed-change output shaft at a third output-side gear ratio that rotates the speed-change output shaft at a higher speed than a second speed ratio on the output side;
output-side first to third clutch mechanisms for engaging and disengaging power transmission of the output-side first to third transmission mechanisms;
a speed change 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 transmission output shaft;
a control device that controls the operation of the output adjusting member, the input side first and second clutch mechanisms, and 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 when the rotation speed of the speed change output shaft is lower than a first switching speed, and By disengaging the second input side clutch mechanism, disengaging the first output side first clutch mechanism and disengaging the other output side clutch mechanism, the first element is separated from the drive source. While creating a first transmission state in which the second element acts as an input portion for the reference power to be operatively transmitted and the second element acts as an output portion for the combined rotational power, the gear shift operation member is operated to increase speed. The output adjusting member is operated so that the HST output shifts from the first HST speed to the second HST speed, and in an intermediate speed state in which the rotational speed of the shift output shaft is equal to or higher than the first switching speed and lower than the second switching speed. setting the input side first clutch mechanism to the disengaged state and the input side second clutch mechanism to the engaged state, while setting the output side second clutch mechanism to the engaged state and the other output side clutch mechanism to the disengaged state; By doing so, a second transmission state is realized in which the second element acts as an input portion of the reference power and the rotational power of the first element is transmitted to the speed change output shaft at the output side second gear ratio. and operating the output adjusting member so that the HST output shifts from the second HST speed toward the first HST speed in accordance with the speed increasing operation of the shift operating member, and the rotational speed of the shift output shaft increases to the second switching speed or higher. In a high-speed state, the first input-side clutch mechanism is disengaged and the second input-side clutch mechanism is engaged, while the third output-side clutch mechanism is engaged and the other output-side clutch is engaged. A third transmission state in which the second element acts as an input portion of the reference power and the rotational power of the first element is transmitted to the speed change output shaft at the output side third gear ratio by putting the mechanism in the cutoff state. while operating the output adjustment member so that the HST output shifts from the second HST speed side toward the first HST speed side according to the speed increasing operation of the speed change operation member. and at the time of switching between the third transmission states, the rotation speed appearing on the speed change output shaft in the transmission state after switching matches or approaches the rotation speed appearing on the speed change output shaft in the transmission state before switching. to operate the output adjustment member,
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 rotational speed of the first element and the first transmission when the rotational speed of the second element due to the rotational power transmitted through is the same and the HST output is set to the second HST speed in the second transmission state The transmission structure is set so as to be the same as the rotational speed of the first element due to the rotational power transmitted through the input side first transmission mechanism in the event of a state. a transmission intermediate shaft that is axially non-rotatably connected to the second element;
a speed change transmission shaft that is rotatably fitted around the speed change intermediate shaft and connected to the first element so as not to rotate relative to the speed change transmission shaft;
The first input-side transmission mechanism includes a first input-side driving gear supported so as to be relatively rotatable on a main drive shaft operatively connected to the drive source; an input-side first driven gear that is non-rotatable relative to the transmission shaft;
The input-side second transmission mechanism includes: an input-side second drive gear supported by the main drive shaft so as to be relatively rotatable; and a second driven gear on the input side,
The output-side first transmission mechanism includes: an output-side first drive gear supported by the speed change intermediate shaft so as not to rotate relative thereto; a supported output side first driven gear;
The output-side second transmission mechanism includes: an output-side second drive gear supported by the speed change transmission shaft so as not to rotate relative to the speed change transmission shaft; a supported output side second driven gear;
The third output-side transmission mechanism includes a third output-side drive gear supported by the speed change transmission shaft so as not to rotate relatively, and a third output-side drive gear that is operably connected to the third output-side drive gear and rotatable relative to the speed change output shaft. 21. The transmission structure of claim 20, further comprising a supported output side third driven gear. A travel transmission shaft disposed downstream of the speed change output shaft in the direction of transmission, and forward/rearward switching capable of switching the direction of rotation of the drive force between the speed change output shaft and the travel transmission shaft between the forward direction and the reverse direction. 22. A transmission structure as claimed in any preceding claim, comprising a mechanism. an HST that continuously shifts the rotary power operatively input from the drive source to the pump shaft into the rotary power from at least the first HST speed to the second HST speed according to the operating position of the output adjusting member, and outputs the rotary power from the motor shaft; ,
a planetary gear mechanism having first to third elements, wherein the third element acts as an input for HST output;
an input-side first transmission mechanism capable of transmitting the rotational power of the drive source to the first element at an 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 for engaging and disengaging power transmission of the input-side first transmission mechanism and the input-side second transmission mechanism, respectively;
a speed change output shaft;
a travel transmission shaft arranged downstream in the transmission direction from the speed change output shaft;
A forward/rearward movement that is inserted in a transmission path from the speed change output shaft to the traveling transmission shaft and is switchable between a forward transmission state in which the traveling transmission shaft is rotated in a forward direction and a reverse transmission state in which the traveling transmission shaft is rotated in a reverse direction. a switching mechanism;
an output-side first transmission mechanism capable of transmitting the rotational power of the second element to the speed change output shaft at an output-side first gear ratio;
an output-side second transmission mechanism capable of transmitting the rotational power of the first element to the speed change output shaft at an output-side second gear ratio;
A third output-side 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/reverse switching mechanism in a forward transmission state. The rotational power of the first element through the output side third transmission mechanism is higher than the rotational speed of the travel transmission shaft when the rotational power of the first element is transmitted to the travel transmission shaft via an output-side third transmission mechanism having a transmission gear ratio set so that the rotational speed of the traveling transmission shaft when operation is transmitted to the traveling transmission shaft becomes high;
output-side first to third clutch mechanisms for engaging and disengaging power transmission of the output-side first to third transmission mechanisms;
a speed change operation member;
an HST sensor that directly or indirectly detects the shift state of the HST;
a control device that controls the operation of the output adjusting member, the input side first and second clutch mechanisms, and the output side first to third clutch mechanisms,
The control device is
actuating the output adjustment member so that the HST output becomes the first HST speed that makes the combined rotational power zero in response to the operation of the shift operation member to the zero speed position;
When the speed change operation member is operated in the forward speed range from the zero speed position to the forward speed first switching speed position, the input side first clutch mechanism is engaged and the input side first clutch mechanism is engaged. The first element is operatively transmitted from the drive source by disengaging the second clutch mechanism, engaging the first clutch mechanism on the first output side, and disengaging the other clutch mechanism on the output side. The forward/reverse switching mechanism is placed in the forward transmission state while the first transmission state in which the second element acts as the input portion of the reference power applied and the second element acts as the output portion of the combined rotational power, and actuating the output adjusting member so that the HST output shifts from the first HST speed side toward the second HST speed side in accordance with the speed increasing operation of the shift operating member;
when the speed change operation member is operated in a forward intermediate speed range between the first forward switching speed position and the second forward switching speed position, the first input clutch mechanism is disengaged; By engaging the second input-side clutch mechanism, engaging the second output-side clutch mechanism, and disengaging the other output-side clutch mechanisms, the second element is used to input the reference power. a second transmission state in which the rotational power of the first element is transmitted to the speed change output shaft at a second gear ratio on the output side, while bringing the forward/reverse switching mechanism into the forward transmission state; and operating the output adjustment member so that the HST output shifts from the second HST speed side toward the first HST speed side in accordance with the speed increasing operation of the shift operation member;
When the speed change operation member is operated in a forward high speed range exceeding the second forward switching speed position, the first input side clutch mechanism is disengaged and the second input side clutch mechanism is engaged. By engaging the output-side third clutch mechanism and disengaging the other output-side clutch mechanism, the second element acts as an input portion for the reference power and rotates the first element. The HST output is increased in accordance with the speed increasing operation of the speed change operation member while the third transmission state in which the power is transmitted to the traveling transmission shaft as the driving force in the forward direction through the output side third transmission mechanism is realized. actuating the output adjusting member so as to shift from the second HST speed side toward the first HST speed side;
When the speed change operating member passes through the forward second switching speed position between the forward intermediate speed range and the forward high speed range, the rotation of the traveling transmission shaft in the transmission state that appears immediately after passing through. actuating the output adjustment member so that the speed matches or approaches the rotational speed of the travel output shaft in the transmission state that appears immediately before passage;
When the speed change operation member is operated in the reverse side low speed range from the zero speed position to the reverse side first switching speed position, the forward/reverse switching mechanism is operated while the first transmission state is brought about. activating the output adjusting member so that a reverse transmission state is established, and the HST output shifts from the first HST speed side to the second HST speed side in accordance with the speed increasing operation of the shift operating member;
when the speed change operation member is operated in the reverse high speed range exceeding the first reverse speed switching position, causing the forward/reverse switching mechanism to enter the reverse transmission state while exhibiting the second transmission state; and operating the output adjustment member so that the HST output shifts from the second HST speed side toward the first HST speed side in accordance with the speed increasing operation of the shift operation member;
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. and 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 through is the same and the HST output is set to the second HST speed in the second transmission state The transmission structure is set so as to be the same as the rotational speed of the first element due to the rotational power transmitted through the input side first transmission mechanism in the event of a state. comprising a speed change intermediate shaft connected to the second element so as not to rotate relative to the axis;
The first input-side transmission mechanism includes a first input-side driving gear supported in a relatively rotatable manner on a main drive shaft operably connected to the drive source, and a state in which the first input-side driving gear is supported in a relatively rotatable manner on the transmission intermediate shaft. , an input-side first drive gear and an input-side first driven gear operatively connected to the first element,
The input-side second transmission mechanism includes an input-side second drive gear supported relatively rotatably on the main drive shaft and the input-side second drive gear supported relatively non-rotatably on the transmission intermediate shaft. and an input-side second driven gear operatively connected to
The output-side first transmission mechanism has an output-side first driven gear operatively connected to the input-side second driven gear in a state of being relatively rotatably supported by the speed change output shaft,
The second output-side transmission mechanism has a second output-side driven gear operably connected to the first input-side driven gear while being relatively rotatably supported by the speed change output shaft,
The output-side third transmission mechanism has an output-side third driven gear operably connected to one of the output-side first and second output-side driven gears while being relatively rotatably supported by the traveling transmission shaft,
the input-side first and second clutch mechanisms are respectively 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;
the output side first and second clutch mechanisms are respectively 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;
24. The transmission structure according to claim 23, wherein the output side third clutch mechanism is supported by the travel transmission shaft so as to engage and disengage the output side third driven gear with the travel transmission shaft. a hollow housing body;
a first bearing plate detachably connected to the housing body;
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;
the main drive shaft, the transmission intermediate shaft, the transmission output shaft, and the traveling transmission shaft are supported by the first and second bearing plates in parallel with each other;
The input-side first and second drive gears and the input-side first and second clutch mechanisms are arranged between the input-side first and second drive gears with respect to 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 within the compartment sandwiched between the first and second bearing plates,
The input-side first and second driven gears are located in the partitioned space of the speed change intermediate shaft while being positioned at the same positions as the input-side first and second drive gears in the axial direction, respectively. supported by part
The output-side first and second driven gears and the output-side first and second clutch mechanisms are configured such that the output-side first and second driven gears are axially aligned with the input-side second and first driven gears, respectively. and the output-side first and second clutch mechanisms are positioned between the input-side first and second driven gears in the axial direction, the speed change output shaft within the partitioned space supported by the part located at
The output-side third driven gear and the output-side third clutch mechanism are configured such that 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 third With respect to the axial direction, the clutch mechanism is located on the opposite side of the output side first and second clutch mechanisms with respect to one of the output side first and second driven gears, and supported by a portion located within the partitioned space;
25. The transmission structure according to claim 24, wherein the forward/reverse switching mechanism is supported by a portion of the speed change output shaft and the travel transmission shaft located outside the partitioned 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 provided on the inner surface of the front housing body near the rear opening of the front housing body,
26. The transmission structure according to claim 25, wherein the second bearing plate is detachably connected to a boss provided on the inner surface of the rear housing body in the vicinity of the front opening of the rear housing body. . The first and second gear ratios on the output side are set so that when the HST output is set to the second HST speed, the rotation speed appearing on the gear shift output shaft is the same in the first and second transmission states. 27. A transmission structure as claimed in any one of claims 20 to 26, characterized in that At the time of switching between the first transmission state and the second transmission state, the control device is arranged such that the rotation speed appearing on the transmission output shaft in the transmission state after switching is the same as the rotation speed appearing on the transmission output shaft in the transmission state before switching. 27. A transmission structure as claimed in any one of claims 20 to 26, wherein the power adjusting member is actuated to match or approximate the rotational speed being delivered. When the rotation direction of the rotational power input to the pump shaft is the forward rotation direction, the HST outputs the rotational power in one of the forward and reverse directions as the HST output of the first HST speed and the HST output of the second HST speed. 29. The transmission structure according to any one of claims 1 to 28, wherein the rotational power in the other forward and reverse direction is output as . 30. A transmission structure as claimed in any preceding claim, wherein the planetary gear mechanism internal gear, carrier and sun gear respectively form the first, second and third elements. a driving source;
drive wheels;
and a transmission structure according to any one of claims 1 to 30 inserted in a traveling system transmission path from the drive source to the drive wheels,
A working vehicle, wherein a switching speed of the speed change output shaft is set higher than a working speed range.

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