JP4909370B2 - Work vehicle transmission - Google Patents

Description

  The present invention includes a travel drive system that transmits engine power to a travel device, and a work device drive system that transmits engine power to an external power take-out shaft, and shifts and transmits power to the travel device to the travel drive system. The present invention also relates to a transmission device for a work vehicle that includes a hydrostatic continuously variable transmission that includes a hydraulically operated PTO clutch that intermittently transmits power to an external power take-off shaft in the work device drive system.

As a transmission device for this type of work vehicle, those having the structures described in [1] and [2] below are conventionally known.
[1] A structure in which when the both side brake pedals are depressed, the traveling transmission is stopped and the PTO clutch is disengaged (see, for example, Patent Document 1).
[2] Selectable operation can be switched between a state in which high-pressure hydraulic oil in a drive circuit from a hydraulic pump to a hydraulic motor of a hydrostatic continuously variable transmission is sent to the bypass circuit and a state in which the feed to the bypass circuit is released. Provided with a simple operation means (for example, see Patent Document 2).

JP 2008-137436 A (paragraph numbers 0028, 0029, 0035, 0037, FIGS. 3 and 4) Japanese Unexamined Patent Publication No. Sho 63-38030 (the upper right column on the second page and the lower right column on the same page, and FIGS. 1 and 2 of the publication drawings)

In the conventional structure shown in [1] above, for example, in a tilling operation in which a rotary tiller is connected to the rear portion of the tractor main unit and driven by the PTO shaft, when stopping traveling during the tilling operation, both side brake pedals are used. Since the PTO clutch is automatically disengaged by depressing and stopping the travel, it is possible to avoid an increase in the stopping distance due to the tractor unit being pushed by the rotary tiller driven by rotation. It is useful.
However, in this structure, both side brake pedals are operated, so that the operation force requires a relatively large pedaling force, and the aircraft is turned by stepping on one side brake pedal. There is an inconvenience that the stop operation cannot be performed when the user is in the car.

  Further, in the conventional structure shown in [2], a switch for detecting the neutral position of the speed change lever or the position of the cockpit is provided instead of the side brake pedal, and the hydraulic pump is based on the detection signal of the switch. The high-pressure hydraulic fluid in the drive circuit from the hydraulic motor to the hydraulic motor can be switched between a state in which the high-pressure hydraulic oil is fed into the bypass circuit and a state in which the feed into the bypass circuit is released. According to this structure, the driving state by the hydrostatic continuously variable transmission can be switched to a state in which power transmission is not performed, but the PTO clutch cannot be operated in conjunction with the operation, Further, the swash plate of the hydrostatic continuously variable transmission cannot be operated to return to the neutral position.

  The object of the present invention is to enable intermittent operation of the power transmission by the hydrostatic continuously variable transmission and the on / off operation of the PTO clutch in association with each other, with less generation of residual tillage and at any operation timing. An object is to obtain a transmission device for a work vehicle.

[Solution 1]
The technical means of the present invention devised to solve the above-mentioned problems includes a travel drive system that transmits engine power to a travel device, and a work device drive system that transmits engine power to an external power take-out shaft, and the travel drive A hydrostatic continuously variable transmission that shifts and transmits power to the traveling device in the system, and a hydraulically operated PTO clutch that intermittently transmits power to the external power take-off shaft in the work device drive system,
One of a power cut-off state in which high-pressure hydraulic oil in the drive circuit from the hydraulic pump to the hydraulic motor of the hydrostatic continuously variable transmission is guided to the oil tank and a state in which the hydraulic motor is driven by releasing the power cut-off state are selected. Provided is a stop operation pedal that can be switched, and provided with a swash plate angle control means for returning the swash plate of the hydrostatic continuously variable transmission to a neutral position in accordance with the stop operation by the stop operation pedal,
The hydrostatic continuously variable transmission and the PTO clutch with respect to the stop operation pedal operate the hydrostatic continuously variable transmission to a neutral position and disengage the PTO clutch as the stop operation pedal is depressed. The PTO clutch engagement operation is performed in accordance with the operation of the stop operation pedal to the release release side, and the operation of the stop operation pedal to the operation side of the stop operation pedal is not performed. The PTO clutch is disengaged after the step transmission is returned to the neutral position, and when the stop operation pedal is depressed, the PTO clutch is engaged before the hydrostatic continuously variable transmission is started. Set the operation timing so that the operation is performed ,
The stop operation pedal is composed of a pedal provided separately from the pair of left and right side brake pedals,
A target speed setting means for setting a target speed by changing a swash plate angle of the hydrostatic continuously variable transmission;
The target speed setting means includes a shift lever that can be held at an arbitrary operation position,
The swash plate angle control means is configured to switch the swash plate angle of the hydrostatic continuously variable transmission corresponding to the operation position of the shift lever when the power cut-off state is canceled by the stop operation pedal and the hydraulic motor is driven. Is set as the swash plate angle corresponding to the target speed of the hydrostatic continuously variable transmission, and the hydrostatic non-static speed is set so as to reach the swash plate angle corresponding to the target speed from the neutral position of the hydrostatic continuously variable transmission. The swash plate angle of the step transmission is changed, and the speed of changing the swash plate angle of the hydrostatic continuously variable transmission at this time is gradually changed at a preset acceleration rate. It is characterized by.

[Action and effect]
As described above, in the transmission device for a working vehicle of the present invention according to the solution 1, the stop operation pedal is only operated by linking the hydrostatic continuously variable transmission and the PTO clutch to the stop operation pedal. Thus, it is possible to automatically perform power interruption by supplying / discharging high-pressure hydraulic oil in the hydrostatic continuously variable transmission and on / off operation of the PTO clutch.
In the operation to the depression side of the stop operation pedal, the PTO clutch is disengaged after the hydrostatic continuously variable transmission returns to the neutral position, and in the operation to the depression release side of the stop operation pedal, the hydrostatic pressure is The operation timing is set so that the operation of engaging the PTO clutch is performed before the traveling by the continuously variable transmission is started. Therefore, when the PTO clutch is disengaged before the hydrostatic continuously variable transmission returns to the neutral position, or when traveling by the hydrostatic continuously variable transmission is started before the PTO clutch is engaged. Compared to this, the possibility that the remaining plowed part remains in the field can be reduced.

Therefore, simply by operating the stop operation pedal, it is possible to perform an operation with good operability by linking the power transmission intermittent operation and the PTO clutch on / off operation with the hydrostatic continuously variable transmission.
In addition, in the operation to the depression side of the stop operation pedal, the PTO clutch is disengaged after the hydrostatic continuously variable transmission returns to the neutral position, and the operation to the depression release side of the stop operation pedal is performed. There is an advantage that the operation timing is set so that the operation of engaging the PTO clutch is performed before the traveling by the hydrostatic continuously variable transmission is started, and the operation can be performed with less possibility that the remaining tillage portion remains in the field. is there.

As described above, in the transmission device for a working vehicle according to the present invention according to the solving means 1, the swash plate angle control means until the swash plate angle corresponding to the target speed is reached from the neutral position of the hydrostatic continuously variable transmission. Since the swash plate angle change speed is gradually changed at a preset acceleration rate, when the hydrostatic continuously variable transmission is stopped by the stop operation pedal, the aircraft is started again. The aircraft can be started slowly by changing the swash plate angle slowly at a preset acceleration rate.

Accordingly, there is an advantage that it is possible to perform traveling control that avoids sudden start of the airframe by merely performing intermittent transmission of power by the hydrostatic continuously variable transmission and on / off operation of the PTO clutch with a simple stop operation pedal. is there.

As described above, in the work vehicle transmission according to the solution 1 of the present invention, the stop operation pedal is constituted by a pedal provided separately from the pair of left and right side brake pedals. It is easy to adopt a structure that can be operated with a light operation that does not require pedal effort.
Further, even during a turning operation in which one of the side brake pedals is operated, the stop operation pedal can be operated immediately without having to temporarily return the side brake pedal.

Therefore, there is an advantage obtained with a stop operation pedal with good operability, where a pedal that can be operated lightly can be operated at an arbitrary timing.

It is a whole side view which shows the tractor comprised by the tiller specification. It is a diagram which shows a transmission system. It is a block diagram which shows a control system. It is operation | movement explanatory drawing of a side brake pedal. It is a top view which shows the arrangement | positioning state of a side brake pedal and a stop operation pedal. 1 is a hydraulic circuit diagram of a hydrostatic continuously variable transmission.

[Overall configuration of work vehicle]
FIG. 1 shows a tractor configured as a rotary tiller specification, which is an example of a work vehicle including a transmission device according to the present invention.
This tractor is configured by connecting a rotary tiller 4 to a rear portion of a four-wheel drive tractor main machine 1 having a front wheel 2 and a rear wheel 3 so as to be movable up and down. The vehicle body of the tractor main unit 1 is configured as a monobody type in which an engine 5, a main clutch housing 6, a main transmission case 7, a mid case 8, and a transmission case 9 are directly connected in series. A front axle case 11 is supported by a front frame 10 connected to the engine 5 so as to be capable of rolling, and a front wheel 2 is supported by the left and right sides of the front axle case 11 so as to be steerable. 3 is pivotally supported. A link mechanism 13 that is driven up and down by a lift arm 12 is provided at the rear of the mission case 9, and the rotary tiller 4 is connected to the link mechanism 13.

[Configuration of transmission system]
FIG. 2 shows a transmission system in the tractor main unit 1. The output of the engine 5 is transmitted to the input shaft 16 provided in the main transmission case 7 through the main clutch 15, and the transmission power taken out from the output shaft 17 provided in the main transmission case 7 is converted into a gear-type auxiliary transmission. After being shifted in three stages by the device 18, it is transmitted to the left and right rear wheels 3 via the rear differential device 19 and the side brake 22. A part of the traveling system power changed by the auxiliary transmission 18 is taken out from the lower part of the transmission case 9, transmitted to the front axle case 11 via the transmission shaft 20, and left and right front wheels via the front differential device 21. 2 is transmitted.

  The main transmission case 7 is internally provided with a hydrostatic continuously variable transmission (HST) 23. The continuously variable transmission 23 includes a variable displacement hydraulic pump 23P configured in an axial plunger type and a hydraulic motor 23M, and changes the swash plate angle in the hydraulic pump 23P that is driven to rotate at a constant speed by the input shaft 16. Then, the output shaft 17 of the hydraulic motor 23M that receives the pressure oil is continuously rotated by forward rotation or reverse rotation by changing the discharge direction and discharge amount of the discharged pressure oil. Yes.

  The input shaft 16 extends rearward through the hydraulic pump 23P, and a part of the constant speed rotational power transmitted to the input shaft 16 is further rearward through a PTO clutch 24 built in the midcase 8. Then, the rotary tiller 4 is driven by a constant speed PTO power regardless of the traveling speed change.

The continuously variable transmission 23 (HST) is shift-controlled by hydraulic servo means, and the configuration thereof is shown in FIGS.
The swash plate angle of the hydraulic pump 23P in the continuously variable transmission 23 is configured to be able to be changed in the forward and reverse directions by a return servo cylinder 30, and the swash plate angle is detected by a swash plate angle sensor 31 using a potentiometer. And input to the control device 32. The servo cylinder 30 is urged and returned by a pair of return springs 33 to a neutral position where the swash plate angle becomes zero, and a forward proportional control valve 34 and a reverse proportional control valve 35 connected to the control device 32. The servo cylinder 30 is expanded and contracted by hydraulic control via the.

  The proportional control valves 34 and 35 are biased to a return position where the servo cylinder 30 communicates with the tank when the energization control is not performed. When both the proportional control valves 34 and 35 are in the return position, the servo cylinder 30 is In a free state, the continuously variable transmission 23 returns to neutral. The pressure oil supply path from the pump 36 to the proportional control valves 34 and 35 is provided with a relief valve 37, which limits the maximum system pressure in the hydraulic servo means.

[Configuration of gear shifting operation system]
The tractor main unit 1 is equipped with a shift pedal 38 and a shift lever 39 as shift operating tools. As shown in FIG. 5, the shift pedal 38 is disposed on the right side of the foot of the driver seat 14, and the shift lever 39 is disposed on the left side of the driver seat 14.
The speed change pedal 38 can be stepped forward and backward, and is mechanically urged to return to the neutral position by a cam mechanism (not shown).
The depression position of the shift pedal 38 is detected by the potentiometer 40 and input to the control device 32. Information on the depression position of the shift pedal 38 detected by the potentiometer 40, feedback information from the swash plate angle sensor 31, and Based on detection information of a stop operation detection switch 61 that detects an operation of a stop operation pedal 60 described later, the proportional control valves 34 and 35 are controlled by servo control means 100 provided in the control device 32.
That is, the servo control means 100 controls the operation of the proportional control valves 34 and 35 so that the servo cylinder 30 is expanded and contracted according to the depression direction and the depression amount of the shift pedal 38 detected by the potentiometer 40. By making the swash plate angle corresponding to the depression of 38, stepless forward shift and reverse shift are performed.
When the potentiometer 40 detects the release of the shift pedal 38, the operation of the proportional control valves 34 and 35 is controlled to automatically return the shift pedal 38 to the neutral position, cut off the output of the driving thrust and stop the driving. To control.

Although not shown, the shift lever 39 is mechanically linked in a one-sided state so that the shift pedal 38 can be operated only in the forward shift direction, and is supported so as to be able to hold friction at an arbitrary operation position. The operating position of the shift lever 39 is detected by a potentiometer 40 that detects the operating position of the shift pedal 38. In a state where the shift lever 39 is held at the linkage release position n, the linkage between the shift lever 39 and the shift pedal 38 is released, and the shift pedal 38 can be depressed in the entire region from the forward range to the reverse range.
As the speed change lever 39 is operated forward from the linkage release position n shown in FIG. 3, the speed change pedal 38 is operated in the forward depression direction (forward speed increasing direction), and the speed change lever 39 is operated arbitrarily in the forward speed change range. By holding the friction at the position, the neutral return of the speed change pedal 38 that is urged to return to the neutral position is prevented and held in an arbitrary forward shift range, and the speed is constant at an arbitrary speed corresponding to the operating position of the shift lever 39. Fast forward travel is performed. That is, the speed change lever 39 constitutes target speed setting means for setting the target speed of the hydrostatic continuously variable transmission.
In the state where the shift pedal 38 is held at the intermediate position of the forward shift range by the shift lever 39, it is permitted to depress the shift pedal 38 in the further forward speed increasing direction. It returns to the speed set by the lever 39.

[Linked configuration for side brake pedal]
As shown in FIG. 6, in the vicinity of the shift pedal 38, a pair of side brake pedals 41, which are linked to the left and right side brakes 22 and linked to the left and right side brakes 22, are arranged in parallel on the left and right sides. The side brake pedal 41 is linked to the operating arm 43 through a link mechanism 42.
The link mechanism 42 does not rotate the operating arm 43 only by operating one of the side brake pedals 41 in the depressing direction that is the travel stop direction, and only when the both side brake pedals 41 are simultaneously depressed. The operation arm 43 is configured to be rotated at an angle corresponding to the amount of depression, and the rotation angle of the operation arm 43 is detected by the potentiometer 44 and input to the control device 32.

The PTO clutch 24 is configured as a multi-plate friction clutch that is engaged when a hydraulic pressure is applied, and is turned off by a spring biasing force when the hydraulic pressure is released. Control is performed via an electromagnetic proportional control valve 45 connected to the control device 32.
A PTO clutch lever 46 is provided on the right side of the driver seat 14, the operation position of the PTO clutch lever 46 is detected by the PTO on / off switch 47, and the detection information is input to the control device 32. . In addition, for the control device 32, the state in which the PTO clutch 24 and the left and right side brakes 22 are linked and the linkage operation is released, and the PTO clutch 24 and the left and right side brakes 22 are independent of each other. A linkage state changeover switch 48 for switching the operation state is also connected.
The control device 32 controls the electromagnetic proportional control valve 45 based on the detection information of the potentiometer 44 for detecting the rotation angle of the operating arm 43, the PTO on / off switch 47, and the linkage state changeover switch 48. First PTO pressure control means 101 for outputting a signal is provided.

Therefore, when the PTO clutch lever 46 is operated to the “disengaged” position, the proportional control valve 45 is controlled so that the application of the hydraulic pressure is released, the PTO clutch 24 is in the clutch disengaged state, and the PTO clutch lever 46 is moved to “ When operated to the “ON” position, a control signal is output from the control device 32 to the proportional control valve 45 so that a predetermined high hydraulic pressure is applied, and the PTO clutch 24 enters the clutch engaged state.
When the linkage state changeover switch 48 is in the “off” state, the control device 32 determines whether or not the PTO clutch is operated regardless of the operation of the left and right side brake pedals 41 according to the operation position of the PTO clutch lever 46. 24 is maintained in the “OFF” or “ON” state.
Only when the linkage state changeover switch 48 is operated to “ON” and the operation position of the PTO clutch lever 46 is “ON”, it is linked to the operation of the left and right side brake pedals 41 to The clutch 24 is controlled as follows.

  When the left and right side brake pedals 41 are operated in the simultaneous depression state, the braking force of each side brake 22 increases as the depression amount of the side brake pedal 41 increases, and the hydraulic servo means for speed change operation is used. A servo cylinder 30 and a proportional control valve 45 for turning on / off the PTO clutch 24 are controlled as follows.

  As shown by the solid line in FIG. 4, the left and right side brake pedals are set in a state where the speed change lever 39 is held at an arbitrary forward position to set the forward speed and the PTO clutch lever 46 is operated to the “ON” position. When 41 is depressed and returned to the return position (a), both side brakes 22 are in the brake release state, the forward proportional control valve 34 is energized and the servo cylinder 30 is actuated to a predetermined position. The step transmission 23 is held in a forward shift state corresponding to the operation position of the shift lever 39. In addition, the first PTO pressure control means 101 outputs a control signal to the proportional control valve 45 to the PTO clutch 24 so that a high hydraulic pressure is supplied to the PTO clutch 24 to bring the clutch into an engaged state.

  If the both side brake pedals 41 are simultaneously depressed from this state, the left and right side brakes 22 exert a braking action as the amount of depression increases, and the servo cylinder 30 is activated based on the rotation angle of the operating arm 43. The operation is controlled in the deceleration direction, and the traveling speed gradually decreases from the forward speed set by the speed change lever 39.

  When the both side brake pedals 41 are simultaneously depressed to the preset first depression position (b), the servo control means 100 controls the proportional control valve 34 regardless of whether the shift lever 39 is held in the forward shift range. , 35 is cut off, the servo cylinder 30 is returned to the neutral position, the continuously variable transmission 23 is in the neutral state, and the traveling drive by the continuously variable transmission 23 is stopped.

  As the both side brake pedals 41 are further depressed beyond the first depression position (b), the amount of depression of both side brake pedals 41 increases and the braking force gradually increases. As shown in FIG. 5, the pressure is maintained at a constant pressure while maintaining almost no change from the state at the return position (a). However, when the both side brake pedals 41 are depressed to the second depression position (c) set in advance as an operation position at which the maximum braking force of each side brake 22 can be obtained, from the potentiometer 44 that detects this. Along with the detection signal, the first PTO pressure control means 101 outputs a control signal so as to operate the proportional control valve 45 to the oil passage opening side, and the clutch pressure of the PTO clutch 24 is rapidly reduced. The frictional force disappears and the clutch is completely disengaged.

  Note that when the front wheel 2 is steered and only one side brake pedal 41 on the inner side of the turn is depressed to make a small turn, the operating arm 43 does not turn, so the above-described deceleration control and PTO clutch 24 disengagement control. Is never done.

  When the both side brake pedals 41 are depressed to the third depression position (d) which is the depression limit position beyond the second depression position (c), the relief valve 37 of the hydraulic servo means is based on the rotation of the operating arm 43. Is mechanically forcibly released, the system pressure of the hydraulic servo means is reduced to zero, and pressure oil is supplied to the servo cylinder 30 regardless of the control operation state of the proportional control valves 34 and 35 for traveling speed change. Is released, and the continuously variable transmission 23 is neutrally restored.

  As described above, when the both side brake pedals 41 are stepped down to the third depression position (d), the pressure oil supply to the servo cylinder 30 is forcibly released and the continuously variable transmission 23 is returned to the neutral state. Even if a situation occurs in which the proportional control valves 34 and 35 do not return to the return position due to a malfunction in the electric system, the stepless transmission 23 is returned to the neutral state as long as both the side brake pedals 41 are depressed to the limit. It is possible to stop running.

  The interlocking relationship between the two side brake pedals 41, the PTO clutch 24, and the servo cylinder 30 works in the same way in both the depression direction and the depression release direction of the both side brake pedals 41.

[Linkage configuration for stop operation pedal]
As shown in FIG. 6, the hydrostatic continuously variable transmission 23 having a first oil passage A or the like that becomes a high pressure side when moving forward and a second oil passage B that becomes a low pressure side when moving forward includes a continuously variable transmission. A stop operation pedal 60 is provided to release the hydraulic pressure of the first oil passage A, which is a drive circuit of the device 23, and to block power transmission to the traveling device.
That is, the return oil path 63 is provided across the first oil path A and the oil tank T, which are high pressure during forward travel in the continuously variable transmission 23, the unload valve 64 is provided in the return oil path 63, and the return oil path 63. A throttle valve 65 is provided between the unload valve 64 and the oil tank T in FIG. The stop operation pedal 60 is configured to release the hydraulic pressure of the first oil passage A of the continuously variable transmission 23 by the unload valve 64 to cut off power transmission to the traveling device.

A stop operation detection switch 61 that detects a power transmission cut-off state due to depression of the stop operation pedal 60 is provided, and a detection signal of the stop operation detection switch 61 is transmitted to the control device 32.
The control device 32 is provided with second PTO pressure control means 102 for operating the proportional control valve 45 based on whether or not the stop operation pedal 60 is depressed, which is detected by the stop operation detection switch 61, and the servo cylinder The servo control means 100 that operates the proportional control valves 34 and 35 that supply pressure oil to 30 is also controlled based on whether or not the stop operation pedal 60 is depressed, which is detected by the stop operation detection switch 61.

The second PTO pressure control means 102 determines that the stop operation pedal 60 has been depressed when the stop operation detection switch 61 that detects one of the on and off states is in the on state, and the stop operation detection switch 61 When is in the cut-off state, it is determined that the stop operation pedal 60 has been released.
In the second PTO pressure control means 102, when the stop operation detection switch 61 is switched from the off state to the on state, a control command is output to the proportional control valve 45 so that the PTO clutch 24 is turned off.
Conversely, when the stop operation detection switch 61 is switched from the on state to the off state, a control command is output so that the PTO clutch 24 is engaged and operated with respect to the proportional control valve 45.

The servo control unit 100 also determines that the stop operation pedal 60 is depressed when the stop operation detection switch 61 is in the on state, and the stop operation pedal 60 when the stop operation detection switch 61 is in the off state. It is determined that the stepping-in state is canceled.
Then, when the stop operation detection switch 61 is in the on state, the energization to the proportional control valves 34 and 35 for supplying pressure oil to the servo cylinder 30 is cut off, and as shown in FIG. 35 is switched to the pressure oil discharge side, the pressure chamber of the servo cylinder 30 is communicated with the oil tank, and the servo cylinder 30 is returned to the neutral position by the action of the return springs 33, 33, thereby bringing the hydraulic pump 23P to the neutral position. Perform return operation.
On the other hand, when the stop operation detection switch 61 is operated in the OFF state, the proportional control valves 34 and 35 that supply pressure oil to the servo cylinder 30 are energized, and the forward proportional control from the state shown in FIG. The valve 34 is switched to the pressure oil supply side, pressure oil is supplied to the advance pressure chamber of the servo cylinder 30, and the hydraulic pump 23P is operated to the advance side.

The amount of swash plate operation by which the swash plate of the hydraulic pump 23P is operated forward is set based on the detection signal of the potentiometer 40 that detects the operation positions of the shift pedal 38 and the shift lever 39.
That is, the servo control means 100 sets the swash plate angle of the hydrostatic continuously variable transmission 23 corresponding to the operation position of the shift lever 39 detected based on the detection signal of the potentiometer 40 to The swash plate angle corresponding to the target speed of the step transmission 23 is set, and the swash plate angle of the hydraulic pump 23P is changed so as to reach this target speed.
At this time, the speed at which the servo cylinder 30 changes the swash plate angle of the hydraulic pump 23P is relatively moderate according to the acceleration rate stored and set in advance by the servo control means 100, and suddenly starts the aircraft. It is set not to occur. Thus, the potentiometer 40 for detecting the operation position of the speed change lever 39 functions as target speed setting means for setting the target speed of the hydrostatic continuously variable transmission 23, and the servo control means 100, the proportional control valve 34, 35 and the servo cylinder 30 constitute swash plate angle control means.

Then, the second PTO pressure control means 102 and the servo control means 100 to which the detection signal of the stop operation detection switch 61 is inputted are operated to depress the stop operation pedal 60, that is, the stop operation detection switch 61 is turned on. Is detected, the PTO clutch 24 is disengaged after the continuously variable transmission 23 returns to the neutral position. On the other hand, when an operation toward the release release side of the stop operation pedal 60, that is, when the stop operation detection switch 61 is turned off, an operation of turning on the PTO clutch 24 is started before the continuously variable transmission 23 starts running. The mutual operation timing is set so that
This operation timing is based on a time lag that is expected to take until the servo cylinder 30 returns to the neutral position after the proportional control valves 34 and 35 are switched to the pressure oil discharge side, and to the PTO clutch 24. After the proportional control valve 45 that supplies the pressure oil is switched to the pressure oil supply side, the time is set with a time lag that is predicted to cause the clutch pressure of the PTO clutch 24 to reach a predetermined pressure.

One of the second PTO pressure control means 102 and the first PTO pressure control means 101 is selected to control the proportional control valve 45, and the both side brakes In a state where the pedal 41 is operated and the potentiometer 44 detects the rotation angle of the operating arm 43, the proportional control valve 45 is controlled by the first PTO pressure control means 101.
Therefore, in the state where the proportional control valve 45 is controlled by the first PTO pressure control means 101 in this way, even if the stop operation detection switch 61 detects that the stop operation pedal 60 has been depressed, this takes precedence. Then, the PTO clutch pressure is controlled by the first PTO pressure control means 101. Further, even if the stop operation detection switch 61 detects that the stop operation pedal 60 has been depressed first and the PTO clutch pressure is controlled by the second PTO pressure control means 102, the both side brake pedals 41, when the detection signal from the potentiometer 44 is sent to the first PTO pressure control means 101, the control by the second PTO pressure control means 102 is stopped, and the control by the first PTO pressure control means 101 has priority. Done.

[Other Embodiment 1]
In the above embodiment, the return oil passage 63 and the unload valve 64 to the oil tank T are connected in communication with only the first oil passage A that is the drive circuit on the forward travel side of the hydrostatic continuously variable transmission 23. However, the present invention is not limited to this, and the return oil path 63 and the unload valve 64 to the oil tank T are provided on the second traveling side on the reverse travel side. The oil passage B is also connected to the oil passage B, and both the unload valves 64 and 64 are simultaneously operated by the stop operation pedal 60 so that the stop operation can be performed on both the forward side and the reverse side. May be.
In this case, the servo control means determines whether the traveling vehicle has traveled forward or backward before the stop operation pedal 60 is depressed by a detection signal from the potentiometer 40 that detects the operation position of the shift lever 39. 100 is stored in the memory, and the aircraft start direction when the stop operation pedal 60 is operated to the depressing release side is called from the memory and controlled so as to advance in the same direction as the traveling direction before the stop. .

[Second embodiment]
In the above embodiment, the operation timing of the hydrostatic continuously variable transmission 23 and the PTO clutch 24 with respect to the operation of the stop operation pedal 60 is set by providing the above-described time lag. A vehicle speed sensor is installed in the travel transmission system, and a sensor that detects the rotation of the PTO shaft is installed in the PTO transmission system to detect that the vehicle has actually started running or that the PTO shaft has actually started rotating. The operation timing may be set.

[3 of another embodiment]
The stop operation mechanism operated by the stop operation pedal 60 is not limited to the hydrostatic continuously variable transmission 23 but may be a gear transmission or a traveling clutch.

  As a transmission device for a work vehicle to which the present invention is applied, a transmission device for a rice transplanter or a combiner, or a transmission device for a mower or a snowplow may be used.

23 Hydrostatic continuously variable transmission 23P Hydraulic pump 23M Hydraulic motor 24 PTO clutch 25 External power take-off shaft 32 Control means 41 Side brake pedal 60 Stop operation pedal

Claims (1)

A hydrostatic system that includes a travel drive system that transmits engine power to a travel device and a work device drive system that transmits engine power to an external power take-out shaft, and that transmits power to the travel device while shifting the power to the travel drive system. A continuously variable transmission, and a hydraulically operated PTO clutch for intermittently transmitting power to the external power take-off shaft in the working device drive system;
One of a power cut-off state in which high-pressure hydraulic oil in the drive circuit from the hydraulic pump to the hydraulic motor of the hydrostatic continuously variable transmission is guided to the oil tank and a state in which the hydraulic motor is driven by releasing the power cut-off state are selected. Provided is a stop operation pedal that can be switched, and provided with a swash plate angle control means for returning the swash plate of the hydrostatic continuously variable transmission to a neutral position in accordance with the stop operation by the stop operation pedal,
The hydrostatic continuously variable transmission and the PTO clutch with respect to the stop operation pedal operate the hydrostatic continuously variable transmission to a neutral position and disengage the PTO clutch as the stop operation pedal is depressed. The PTO clutch engagement operation is performed in accordance with the operation of the stop operation pedal to the release release side, and the operation of the stop operation pedal to the operation side of the stop operation pedal is not performed. The PTO clutch is disengaged after the step transmission is returned to the neutral position, and when the stop operation pedal is depressed, the PTO clutch is engaged before the hydrostatic continuously variable transmission is started. Set the operation timing so that the operation is performed ,
The stop operation pedal is composed of a pedal provided separately from the pair of left and right side brake pedals,
A target speed setting means for setting a target speed by changing a swash plate angle of the hydrostatic continuously variable transmission;
The target speed setting means includes a shift lever that can be held at an arbitrary operation position,
The swash plate angle control means is configured to switch the swash plate angle of the hydrostatic continuously variable transmission corresponding to the operation position of the shift lever when the power cut-off state is canceled by the stop operation pedal and the hydraulic motor is driven. Is set as the swash plate angle corresponding to the target speed of the hydrostatic continuously variable transmission, and the hydrostatic non-static speed is set so as to reach the swash plate angle corresponding to the target speed from the neutral position of the hydrostatic continuously variable transmission. The swash plate angle of the step transmission is changed, and the speed of changing the swash plate angle of the hydrostatic continuously variable transmission at this time is gradually changed at a preset acceleration rate. A working vehicle transmission device.

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