JP2003207044A - Travelling control device of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a travelling control device of a working vehicle which favorably carries out car speed command operation while maintaining a straight forwarding state even when output rotating speed of an engine changes. <P>SOLUTION: Target speed-change positions of a pair of non-stage transmissions 11R, 11L to separately change respective travelling speed of a pair of left and right travelling devices in non-stage, a pair of hydraulic cylinders 33R, 33L to operate to change speed of them and a pair of operated bodies 29 corresponding to a command position of a main speed-change lever 24 are set, a pair of the hydraulic cylinders 33R, 33L is actuated so as to be at the target speed-change position, and a pair of the hydraulic cylinders 33R, 33L is actuated so that output speed of a pair of the non-stage transmissions 11R, 11L becomes target speed for synchronization when a speed-change position of either one of the operated bodies 29 becomes the target speed-change position. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pair of continuously variable transmissions for continuously changing the traveling speed of a pair of left and right traveling devices driven by the power of an engine, and a pair of continuously variable transmissions. A pair of actuators that shift gears separately, and a vehicle speed command that can move freely within a predetermined operating range that includes a stop command position that commands travel stop, and that commands a higher speed as the amount of operation from the stop command position increases. Means, a turning command means for commanding a turn, a straight ahead control for operating the pair of actuators to run the vehicle straight ahead at a speed corresponding to the vehicle speed command information instructed by the vehicle speed command means, and the turning command And a control means for executing a turning control for operating the pair of actuators to perform a turning commanded by the means. .

[0002]

2. Description of the Related Art A traveling control device for a work vehicle having the above-described structure is applied to a work vehicle such as a combine, and has been conventionally arranged to execute the following control as the straight ahead control. It was That is, when the vehicle speed command means is operated to the stop command position, the vehicle is in a stopped state, and when the vehicle speed command means is moved from the stop command position, the vehicle speed command means changes to a high speed side as the movement operation amount increases. Is configured to set a target travel speed of the vehicle body corresponding to the command position, and the output speeds of the pair of continuously variable transmissions detected by the pair of shift output detection means are both the target travel speed. As described above, the pair of actuators are operated. Thus, by detecting the output speed of each of the pair of continuously variable transmissions, and performing feedback control so that they both become the target traveling speed, By traveling at the speed corresponding to the command state of the vehicle speed command means and at the same speed with the left and right traveling devices having no speed difference, the vehicle body can travel straight ahead satisfactorily without skewing. It is had.

Then, the target traveling speed set when the vehicle speed command means issues an upper limit value of the predetermined operation range is
It was set to a traveling speed corresponding to the traveling speed when shifting the pair of continuously variable transmissions to the maximum shift position with the output rotation speed of the engine adjusted to a preset work setting value. . To add a description, in a work vehicle such as a combine, so that the work device mounted on the work vehicle and driven by the engine is driven at a desired rotation speed,
Before starting work, the output rotation speed of the engine is adjusted in advance to the set value as described above, and the work is performed while maintaining the set state. Was being maintained.

[0004]

In the above-mentioned conventional structure, there is no problem when the output rotation speed of the engine is maintained at the predetermined set value as described above, but the vehicle is run without driving the working device. In such a case, if the vehicle body is made to travel straight while the output rotation speed of the engine is decelerated from the set value to the low speed side, there are the following disadvantages and there is room for improvement. .

That is, when the vehicle body is caused to travel with the upper limit value of the predetermined operation range commanded by the vehicle speed command means, the target traveling speed commanded in accordance with the operation of the vehicle speed command means is as described above. Output speed is the set value and is the traveling speed (maximum speed) when the pair of continuously variable transmissions is shifted to the maximum shift position. The engine output speed is reduced from the set value to the low speed side. In this state, even if the vehicle speed commanding unit commands the upper limit value of the predetermined operation range, the traveling speed of the vehicle body is not the traveling speed (maximum speed) as described above and is lower than that. It becomes an intermediate speed. As a result, when the operator operates the vehicle speed command means to increase the speed, the vehicle speed command means is moved until the vehicle speed command means is operated to a position corresponding to the intermediate speed within the predetermined operation range. Correspondingly, the traveling speed will be increased, but even if it is operated beyond that position to a higher speed side, the speed is not increased any further. As a result, when the worker manually operates the vehicle speed commanding means, the vehicle speed commanding means increases the speed in a range higher than the position corresponding to the intermediate speed in the predetermined operation range. Therefore, even though the vehicle speed command means is moved to the high speed side, the traveling speed of the vehicle body does not increase, and the operator feels that it is difficult to operate, or mistakenly recognizes that the transmission system is faulty. There were disadvantages such as doing.

The present invention has been made by paying attention to such a point, and an object thereof is to avoid the above-mentioned disadvantages even if the output rotation speed of the engine is changed and set.
It is possible to perform the vehicle speed command operation satisfactorily, and moreover,
It is a point to provide a traveling control device for a working vehicle that enables a vehicle to travel straight ahead without being skewed.

[0007]

According to a first aspect of the present invention, there is provided a traveling control device for a working vehicle, wherein a pair of left and right traveling devices driven by the power of an engine continuously change the traveling speed of each of the pair. The step transmission and the pair of actuators for individually shifting the pair of continuously variable transmissions are freely movable within a predetermined operation range including a stop command position for instructing a travel stop, and are operated from the stop command position. As the amount of movement operation increases, a vehicle speed command means for commanding a higher speed, a turning command means for commanding a turn, and a pair of the pair of vehicles for causing the vehicle body to travel straight at a speed corresponding to the vehicle speed command information commanded by the vehicle speed command means. There are provided a straight-ahead control for operating the actuators, and a control means for executing a turn control for operating the pair of actuators to perform the turn commanded by the turn command means. And a pair of continuously variable transmissions, wherein the pair of continuously variable transmissions individually detect a gear shift position of an operated object for gear shifting in each of the pair of continuously variable transmissions. And a pair of shift output detecting means for individually detecting the output speeds of the vehicle speed control means, the control means, when the vehicle speed command means is operated to the stop command position as the straight ahead control, the shift speed is set to the stop speed change position. When the vehicle speed command means is operated to move from the stop command position, it changes to a higher speed side as the movement operation amount increases, and becomes the upper limit shift position when the upper limit value of the predetermined operation range is commanded. In the target shift position setting process for setting the target shift position of the pair of operated objects corresponding to the command position,
A shift position adjusting process for operating the pair of actuators so that each shift position of the pair of operated bodies detected by the pair of shift position detecting means approaches the target shift position, and the shift position adjustment By executing the process,
When the gear shift position of the operated body in at least one of the pair of continuously variable transmissions reaches the control state switching position defined in relation to the target gear shift position, the pair of continuously variable transmissions Is configured to execute each of the speed synchronization processes for operating the pair of actuators based on the detection information of the pair of shift output detection means so that the output speed of the pair becomes the synchronization target speed. To do.

That is, when the turning command means directs the vehicle to go straight and the control means executes straight ahead control, the control means first executes the target shift position setting process. That is, when the vehicle speed command means is operated to move from the stop command position, the vehicle speed command means changes to the higher speed side as the moving operation amount increases, and when the upper limit value of the predetermined operation range is commanded, Thus, the target gear shift positions of the pair of operated bodies corresponding to the command position are set. In other words, the moving operation over the entire predetermined operating range of the vehicle speed command means and the shift operation over the entire operating range of the pair of operated bodies are associated with each other from the command position of the vehicle speed command means to the pair of operated bodies. The target shift position of is set.

Next, the control means executes the shift position adjusting process. That is, the pair of actuators are operated so that the gear shift positions of the pair of operated bodies detected by the pair of gear shift position detecting means become the target gear shift positions. By executing this shift position adjusting process, the pair of continuously variable transmissions continuously changes the traveling speed of each of the pair of traveling devices in correspondence with the moving operation position of the vehicle speed command means. At this time, when the upper limit value of the predetermined operation range is commanded by the vehicle speed command means, both target shift positions of the pair of operated bodies are the upper limit shift position,
The shift output of the pair of continuously variable transmissions becomes the maximum value in the shiftable range. Incidentally, the speed at this time corresponds to the maximum value of the speed at which the shift can be adjusted according to the output rotation speed of the engine if the output rotation speed of the engine is changed.

Further, the control means executes speed synchronization processing. That is, by performing the shift position adjusting process, the shift position of the operated body in at least one of the pair of continuously variable transmissions is used for control state switching determined in relation to the target gear position. When the position is reached, the pair of actuators are operated based on the detection information of the pair of shift output detection means so that the output speed of the pair of continuously variable transmissions becomes the target speed for synchronization. As a result, even if a slight error due to individual difference occurs in the traveling speed of the pair of left and right traveling devices as a result of individually controlling the pair of continuously variable transmissions in the shift position adjustment process, this error is corrected. The traveling speeds of the left and right traveling devices can be corrected to have the same or almost the same value, and the straight traveling state can be maintained.

The control state switching position may be set to the same value as the target shift position, or may be set as a value on the set amount low speed side or the set amount high speed side with respect to the target shift position. Can be implemented in.

The speed synchronizing process is a process of operating each actuator so as to synchronize the speeds so that the output speeds of the pair of continuously variable transmissions become the same after executing the shift position adjusting process. As a specific configuration, the following various configurations can be implemented. That is, in the shift position adjusting process, when the shift position of the operated body in any of the continuously variable transmissions reaches the target shift position, one of the pair of continuously variable transmissions is set to the reference side. Is set as the continuously variable transmission, the reference side continuously variable transmission holds the gear shift position of the operated body at that position, and the output speed of the reference side continuously variable transmission is set to the target speed for synchronization. The speed may be adjusted so that the output speed of the other continuously variable transmission becomes the target speed for synchronization. Further, instead of such a configuration, in the shift position adjusting process, when the shift position of the operated body in any of the continuously variable transmissions reaches the target shift position, the output speed in the continuously variable transmission is changed to the shift speed. After the output detection means detects and sets the detection value as the target speed, the pair of actuators may be operated so that the detection values of the pair of shift output detection means both become the target speed.

By executing the target shift position setting process and the shift position adjusting process in this way, the vehicle speed command means commands the upper limit value of the predetermined operation range regardless of changes in the output rotation speed of the engine. In this case, since it corresponds to the maximum value of the speed that can be adjusted in accordance with the output rotation speed, even if the vehicle speed command means is moved in a range higher than the set speed in the predetermined operation range. There is no disadvantage that the traveling speed does not change, and the vehicle speed command operation can be performed well by operating the vehicle speed command means by effectively utilizing the entire area of the predetermined operation range. Moreover, by executing the speed synchronization processing, the traveling speeds of the left and right traveling devices can be set to the same or substantially the same value and the straight traveling state can be maintained.

Therefore, even if the output rotation speed of the engine is changed and set, the traveling speed of the vehicle body does not increase even though the vehicle speed command means is moved to the high speed side as in the conventional case. It is possible to perform the vehicle speed command operation satisfactorily without the disadvantages that the operator feels that it is difficult to operate, or mistakenly recognizes that the transmission system is faulty. Thus, it has become possible to provide a traveling control device for a work vehicle that enables the vehicle to travel straight ahead without any trouble.

According to a second aspect of the present invention, there is provided the traveling control device for a work vehicle according to the first aspect, wherein the control state switching position is set to the target shift position.

That is, by performing the shift position adjusting process, the shift position of the operated body in at least one of the pair of continuously variable transmissions is the target gear shift position as the control state switching position. Once in position,
The configuration is such that the pair of actuators are actuated based on the detection information of the pair of shift output detecting means so that the output speed of the pair of continuously variable transmissions becomes the target speed for synchronization. Since the target shift position is the shift position corresponding to the command position by the vehicle speed command means, one of the continuously variable transmissions becomes the target shift position corresponding to the command position by the vehicle speed command means, and then the pair of gear shift positions is set. The speed synchronization processing is executed in a state where the output speed of the speed change device becomes the target speed for synchronization. Therefore, by executing this speed synchronization processing, it becomes possible to appropriately travel straight at a speed corresponding to the commanded position by the vehicle speed commanding means or a speed substantially the same as that speed, which is suitable for carrying out claim 1. Means are obtained.

A traveling control device for a work vehicle according to claim 3 is
In Claim 1 or 2, The said control means determines any one continuously variable transmission of the said pair of continuously variable transmission as a reference | standard side continuously variable transmission as the said speed synchronizing process,
In the continuously variable transmission on the reference side, the actuator corresponding to the continuously variable transmission is operated so as to maintain the gear shift position of the operated body in the continuously variable transmission on the reference side. The output speed is set as the synchronization target speed, and the other continuously variable transmission is set based on the detection information of the shift output detection means so that the output speed of the other continuously variable transmission becomes the synchronization target speed. It is characterized in that it is configured to actuate the actuator corresponding to the device.

That is, when the shift position of the operated body in at least one of the continuously variable transmissions of the pair of continuously variable transmissions becomes the control state switching position by the execution of the shift position adjustment processing, One of the continuously variable transmissions is defined as the reference continuously variable transmission. At this time, the condition as to which of the pair of continuously variable transmissions is selected as the reference continuously variable transmission can be appropriately set. For example, a continuously variable transmission in which the gear shift position of the operated body is far from the neutral position may be selected, or a continuously variable transmission in which the gear shift position of the operated body is near the neutral position may be selected. Good.

In the continuously variable transmission on the reference side determined in this way, when the shift position of the operated body in any one of the continuously variable transmissions becomes the control state switching position,
The actuator corresponding to the continuously variable transmission is operated so as to hold the gear shift position of the operated body in the reference side continuously variable transmission. Then, the output speed of the continuously variable transmission on the reference side is set as the target speed for synchronization, and the output information of the other continuously variable transmission is set to the detection information of the shift output detection means so that the output speed of the other continuously variable transmission becomes the target speed for synchronization. Based on this, the actuator corresponding to the other continuously variable transmission is operated.

Instead of such a configuration, for example, each of the pair of continuously variable transmissions may be configured such that each actuator is operated so that the output speed becomes the target speed for synchronization. When configured to
Since the two actuators operate at the same time, extra drive energy is required, which may result in energy loss. However, according to the above configuration, in the continuously variable transmission on the reference side, the gear shift of the operated body is performed. By keeping the position at that position, and in the other continuously variable transmission, by activating the actuator so that the output speed becomes the target speed for synchronization, unnecessary energy consumption is suppressed as much as possible. However, it becomes possible to drive straight ahead properly. Therefore, suitable means for carrying out claim 1 or 2 is obtained.

A traveling control device for a work vehicle according to a fourth aspect of the present invention is
The control unit according to claim 3, wherein the control unit executes the shift position adjustment process so that the shift position of the operated body in one of the continuously variable transmissions of the pair becomes the control state switching position. In that case, the continuously variable transmission is configured to be defined as the reference side continuously variable transmission.

That is, since the continuously variable transmission on the side where the gearshift position of the operated body becomes the control state switching position by the execution of the gearshift position adjustment processing is defined as the reference continuously variable transmission, for example, at that time, The process of determining which of the pair of continuously variable transmissions is far from the stop shift position or which is closer to the stop shift position is selected, and the one farther from the stop shift position is selected. Or
If the configuration is such that the one closer to the stop shift position is selected, there is a disadvantage that the processing takes time, but the above-mentioned configuration does not have such a disadvantage, and a continuously variable transmission on the reference side is provided. The predetermined process can be performed quickly, and a suitable means for carrying out claim 3 can be obtained.

A traveling control device for a work vehicle according to a fifth aspect of the present invention is
The control unit according to claim 3, wherein the control unit executes the shift position adjustment process so that the shift position of the operated body in one of the continuously variable transmissions of the pair becomes the control state switching position. In this case, the continuously variable transmission of the pair of continuously variable transmissions in which the gear shift position of the operated body is located farther from the stop gear shift position is defined as the reference side continuously variable transmission. Is characterized by.

That is, of the pair of continuously variable transmissions, the continuously variable transmission whose shift position of the operated body is located farther from the stop shifting position is defined as the reference continuously variable transmission. The gear shift position of the operated body in the continuously variable transmission is held at the position at that time, and the continuously variable transmission located closer to the stop gear shift position corresponds to the output speed of the tuning target speed. The actuator will be activated.

In a continuously variable transmission in which the gear shift position of the operated body is located far from the stop gear shift position, the gear shift position of the operated body is close to the upper limit gear shift position,
There is a risk that the movement operation from that position to the high speed side may be restricted, but in a continuously variable transmission where the gear shift position of the operated body is located closer to the stop gear shift position, such a movement operation is not possible. It is less likely to be restricted.

Therefore, in the continuously variable transmission that is likely to be restricted by the movement operation, the gear shift position of the operated body is maintained, and the output speed of the continuously variable transmission that is less likely to be restricted by the movement operation is for the tuning. By configuring so that the corresponding actuator is activated to reach the target speed,
A favorable vehicle speed synchronization process is possible without being restricted by the operation of the speed synchronization actuator.
Suitable means for carrying out are obtained.

A traveling control device for a work vehicle according to claim 6 is
The control unit according to claim 5, wherein when the shift position of the operated body in any one of the pair of continuously variable transmissions becomes the control state switching position,
When the gear shift position of the operated body in one of the pair of continuously variable transmissions is located on the lower speed side than the set position, the operated body of the pair of continuously variable transmissions is selected. Is set as the reference side continuously variable transmission, and the gearshift positions of the operated bodies of the pair of continuously variable transmissions are both set as described above. When it is located on the higher speed side than the position, the continuously variable transmission of the pair of continuously variable transmissions, which is located closer to the gear shift position of the operated body than the stop gear shift position, is set to the reference side. It is characterized in that it is configured as a continuously variable transmission.

That is, when the shift position of the operated body in one of the continuously variable transmissions becomes the control state switching position, the shift position of the operated body in one of the continuously variable transmissions, that is, , If the gear shift position of the operated body closer to the stop gear position is lower than the set position, the continuously variable transmission has a gear shift position of the operated body that is far from the upper limit gear shift position. It is less likely that the operation of moving the operating tool will be restricted. Therefore, the continuously variable transmission located on the far side from the stop gear position is defined as the reference side continuously variable transmission, and the continuously variable transmission located on the far side from the stop gear position, that is, as described above. Since the continuously variable transmission, which is less likely to be restricted by the movement operation, is configured so that the corresponding actuator is operated so that the output speed becomes the target speed for tuning, the operation of the actuator for speed synchronization is restricted. It is possible to perform favorable vehicle speed synchronization processing with little fear.

Further, when the gear shift position of the operated body in one of the continuously variable transmissions becomes the control state switching position, the gear shift positions of the operated bodies of the pair of continuously variable transmissions are both the above-mentioned. Even if the continuously variable transmission located on the side farther from the stop gear shift position is defined as the reference side continuously variable transmission even when it is located on the higher speed side than the set position, the following disadvantages are encountered. There is a point. In other words, since the operated bodies of the continuously variable transmissions are both located on the higher speed side than the set position and close to the upper limit shift position, for example, an error caused by individual differences in the shift position of the operated body. If it occurs, there is a risk that it may be erroneously determined that it is located on the far side even though it is actually located on the side closer to the stop shift position. The operated body located on the side far from the stop shift position may be operated by the corresponding actuator so as to reach the tuning target speed. Then, the vehicle speed synchronization process may not be performed well due to the limitation of the moving operation when the vehicle approaches the upper limit shift position.

Therefore, when the gear shift positions of the operated bodies of the pair of continuously variable transmissions are both located on the higher speed side than the set position, the continuously variable transmission located near the stop gear position is selected. By defining the continuously variable transmission on the reference side and activating the corresponding actuator so that the operated body of the continuously variable transmission on the opposite side reaches the target speed for tuning, the disadvantages as described above are obtained. Thus, the vehicle speed synchronization processing can be performed in a good condition without any problem, and a suitable means for carrying out the fifth aspect can be obtained.

A traveling control device for a working vehicle according to claim 7 is
A pair of continuously variable transmissions that continuously change the traveling speed of a pair of left and right traveling devices driven by the power of the engine, and a pair of actuators that individually shift the pair of continuously variable transmissions. A vehicle speed command means for freely moving within a predetermined operation range including a stop command position for commanding travel stop, and for commanding a higher speed as the amount of movement operation from the stop command position increases, and a turning command means for commanding a turn. A straight-ahead control for activating the pair of actuators to drive the vehicle body to travel straight at a speed corresponding to the vehicle speed command information commanded by the vehicle speed command means; and the turning commanded by the turning command means A traveling control device for a work vehicle, comprising: a control means for executing a turning control for operating a pair of actuators, the output rotation speed of the engine being detected. Provided in the transmission mechanism from the pair of continuously variable transmissions to the pair of traveling devices, and the engine output detection means for detecting the output speed of each of the pair of continuously variable transmissions. A shift state detecting means for detecting a shift state of the auxiliary transmission device, and the control means performs the straight-line control based on the detection information of the engine output detecting means and the shift state detecting means. Upper limit vehicle speed setting process for obtaining an upper limit vehicle speed that can be changed by the continuously variable transmission, when the vehicle speed command means is operated to the stop command position, the vehicle is stopped and the vehicle speed command means is moved from the stop command position. Corresponding to the command position so that it changes to a higher speed side as the movement operation amount increases and the upper limit vehicle speed becomes the upper limit vehicle speed when the upper limit value of the predetermined operation range is commanded. The target output setting process for setting the standard output speed and the pair of continuously variable transmissions detected by the pair of shift output detecting means are set so that the output speeds of the pair of continuously variable transmissions become the target output speed. It is characterized in that it is configured to execute each of the output adjustment processes for operating the actuators.

That is, when the turning command means directs the vehicle to go straight and the control means executes straight ahead control, the control means first executes the upper limit vehicle speed setting process. That is, the upper limit vehicle speed that can be changed by the pair of continuously variable transmissions is obtained based on the detection information of the output rotation speed of the engine detected by the engine output detection means. When the output rotation speed of the engine is changed and adjusted, the upper limit vehicle speed that can be changed by the pair of continuously variable transmissions changes. Therefore, the engine output rotation speed at that time is actually detected and the upper limit vehicle speed is calculated. It asks in.

Then, the control means executes the target vehicle speed setting process. In other words, when the vehicle speed command means is moved from the stop command position, the vehicle speed command means changes to the higher speed side as the amount of movement is increased, and when the upper limit value of the predetermined operation range is commanded, Therefore, the target traveling speed of the vehicle body corresponding to the command position is set. In addition, a pair of vehicle speed command means determines the target traveling speed of the vehicle body from zero speed according to the output rotation speed of the engine by the moving operation over the entire range from the stop command position of the predetermined operation range to the upper limit value. The target traveling speed is set from the commanded position of the vehicle speed commanding means in the associated state so that the continuously variable transmission can change and adjust the speed up to the upper limit vehicle speed.

The control means executes the output adjusting process after executing the target vehicle speed setting process. That is, the pair of actuators are operated so that the output speed of each of the pair of continuously variable transmissions detected by the pair of shift output detecting means becomes the target traveling speed. By executing this output adjustment process, the traveling speeds of the left and right traveling devices can be set to the same or substantially the same value, and the straight traveling state can be maintained.

By executing each of the upper limit vehicle speed setting process and the target vehicle speed setting process in this manner, when the upper limit value of the predetermined operation range is commanded by the vehicle speed command means, a pair of continuously variable transmissions is always provided. The upper limit vehicle speed at which gear shifting is possible is commanded as the target traveling speed by the device, and the traveling speed does not change even if the vehicle speed commanding means is moved in a range higher than the set speed in the predetermined operation range. There is no disadvantage and the vehicle speed commanding operation can be favorably performed by operating the vehicle speed commanding means by effectively utilizing the entire area of the predetermined operation range. Moreover, by executing the output adjusting process, the traveling speeds of the left and right traveling devices can be set to the same or substantially the same value and the straight traveling state can be maintained.

Therefore, even if the output rotation speed of the engine is changed and set, the traveling speed of the vehicle body does not increase even though the vehicle speed command means is moved to the high speed side as in the conventional case. It is possible to perform the vehicle speed command operation satisfactorily without the disadvantages that the operator feels that it is difficult to operate, or mistakenly recognizes that the transmission system is faulty. Thus, it has become possible to provide a traveling control device for a work vehicle that enables the vehicle to travel straight ahead without any trouble.

A traveling control device for a work vehicle according to claim 8 is
A pair of continuously variable transmissions that continuously change the traveling speeds of a pair of left and right traveling devices that are driven by the power of the engine, and a pair of actuators that individually shift the pair of continuously variable transmissions. A vehicle speed command means for freely moving within a predetermined operation range including a stop command position for commanding travel stop, and for commanding a higher speed as the amount of movement operation from the stop command position increases, and a turning command means for commanding a turn. A straight-ahead control for operating the pair of actuators to drive the vehicle body straight ahead at a speed corresponding to the vehicle-speed command information commanded by the vehicle-speed command means, and the turning commanded by the turning command means. A traveling control device for a working vehicle, comprising: a control means for executing a turning control for operating a pair of actuators, wherein each of the pair of continuously variable transmissions is a vehicle control device. A pair of gear shift position detecting means for individually detecting the gear shift position of the operated object for gear shifting, and a pair of gear shift output detecting means for individually detecting the output speeds of the pair of continuously variable transmissions. When the vehicle speed command means is operated to the stop command position as the straight-ahead control, the control means is set to the stop shift position, and when the vehicle speed command means is operated to move from the stop command position, the movement operation amount is large. A target shift for setting the target shift position of the operated body corresponding to the commanded position so that the speed shifts to the high speed side and the shift position becomes the upper limit shift position when the upper limit value of the predetermined operation range is commanded. The position setting process and one of the pair of continuously variable transmissions is set as the main transmission side, and the other continuously variable transmission is set as the follow-up side. The gear shift position of the operated body is The actuator corresponding to the continuously variable transmission is operated so as to approach the target shift position, and the output speed of the continuously variable transmission on the main gear shift side is set as the target speed for tracking, and the continuously variable transmission on the tracking side. So that the output speed of the following becomes the follow-up target speed, based on the detection information of the change-speed output detecting means, each of the shift operation processing for operating the actuator corresponding to the continuously variable transmission on the follow-up side is always executed. It is configured to do.

That is, when the turning command means directs straight ahead and the controller executes straight ahead control, the controller always executes the target shift position setting processing and the shift operation processing. Explaining the target shift position setting processing, when the vehicle speed command means is moved from the stop command position, it changes to a high speed side as the movement operation amount increases, and the upper limit value of the predetermined operation range is commanded. The target shift position of the pair of operated bodies corresponding to the command position is set so that the upper limit shift position is reached when the shift position is set. In other words, the moving operation over the entire predetermined operating range of the vehicle speed command means and the shift operation over the entire operating range of the pair of operated bodies are associated with each other from the command position of the vehicle speed command means to the pair of operated bodies. The target shift position of is set.

Next, the shift operation process will be described. That is, one of the pair of continuously variable transmissions is set as the main transmission side, and the other continuously variable transmission is set as the following side. At this time, after setting once, the set state may be maintained until the end of work, or may be changed appropriately according to the work situation. Is set as
It is sufficient if the other side is set as the follower side. Then, the actuator corresponding to the continuously variable transmission is operated so that the gear shift position of the operated body of the continuously variable transmission on the main gear shift side approaches the target gear shift position, while the continuously variable transmission on the main gear shift side is operated. With the output speed of 1 as the target speed for tracking, the actuator corresponding to the continuously variable transmission on the tracking side is operated so that the output speed of the continuously variable transmission on the tracking side becomes the target speed for tracking. As a result, the traveling speeds of the left and right traveling devices can be set to the same or substantially the same value, and the straight traveling state can be maintained.

In this way, the control means constantly executes each of the target shift position setting processing and the shift operation processing, so that the vehicle speed command means can control the predetermined operation range regardless of the change in the output rotation speed of the engine. When the upper limit value is commanded, it corresponds to the maximum value of the vehicle speed at which the shift can be adjusted according to the output rotation speed, so the vehicle speed command means is set in the range higher than the set speed in the predetermined operation range. There is no disadvantage that the traveling speed does not change even if the moving operation is performed, and the vehicle speed command operation can be performed well by operating the vehicle speed command means by effectively utilizing the entire area of the predetermined operation range. The traveling speed of the traveling device can be set to the same or substantially the same value to maintain the straight traveling state.

Therefore, even if the output rotation speed of the engine is changed and set, the traveling speed of the vehicle body does not increase even though the vehicle speed command means is moved to the high speed side as in the conventional case. It is possible to perform the vehicle speed command operation satisfactorily without the disadvantages that the operator feels that it is difficult to operate, and erroneously recognizes that the transmission system is faulty. Thus, it has become possible to provide a traveling control device for a work vehicle that enables the vehicle to travel straight ahead without any trouble.

A traveling control device for a work vehicle according to claim 9 is
In any one of claims 1 to 8, each of the pair of continuously variable transmissions is constituted by a hydrostatic continuously variable transmission.

When a belt type continuously variable transmission or the like is used as the continuously variable transmission, it is necessary to separately provide a forward / reverse switching mechanism for switching the traveling direction between forward and reverse. When switching the continuously variable transmission on one side from the forward traveling state to the backward traveling state during turning, it is necessary to perform the switching operation of the forward / reverse switching mechanism at the same time as the shifting operation of the continuously variable transmission. , There may be a shift shock when switching between forward and reverse,
If it is composed of a pair of hydrostatic stepless transmissions, the pair of left and right traveling devices can independently change the traveling speed in the forward direction and the reverse direction, respectively, and turn. It is possible to perform the forward / reverse switching operation and the like as smoothly as possible at the time, and it is possible to obtain a suitable means for implementing any one of claims 1 to 8.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] Hereinafter, a case where a first embodiment of a traveling control device for a work vehicle according to the present invention is applied to a combine as an example of the work vehicle will be described with reference to the drawings. .

FIG. 1 shows the entire side surface of a combine, which is an example of a work vehicle. This combine has a traveling body 2 which is driven by a pair of left and right crawler type traveling devices 1R and 1L which is an example of a traveling device. A harvesting and conveying device 3 that cuts the planted culm and conveys it rearward is connected to the front part of the vehicle so that it can be moved up and down, and the traveling machine body 2 receives the harvested culm from the harvesting and conveying device 3 to perform threshing / sorting processing. The threshing device 4 for carrying out the above and the grain tank 5 for storing the grain from the threshing device 4 are mounted, and the boarding operation unit 6 is formed in the front part of the grain tank 5.

As shown in FIGS. 2 to 4, the combine transmits the power from the engine 7 to the input shaft 10 of the transmission case 9 via the belt tension type main clutch 8 and travels from the input shaft 10. Power is transmitted to the pair of continuously variable transmissions 11R and 11L for transmission, and the power after shifting by one of the continuously variable transmissions 11L for traveling is transmitted through the left gear type auxiliary transmission device 13L to the left crawler type traveling device. 1L, and the power after shifting by the other continuously variable transmission 11R for traveling is transmitted to the right crawler type traveling apparatus 1R via the right gear type auxiliary transmission apparatus 13R for traveling drive. Constitutes the transmission mechanism of. On the other hand, engine 7
Power is also supplied to the continuously variable transmission 12 for work,
The power after shifting by the continuously variable transmission 12 for the work,
A transmission mechanism for the reaping work is configured so as to be transmitted to the reaper carrying device 3 via the belt tension type reaping clutch 14. Left and right gear type auxiliary transmissions 13R, 13
L is configured to be able to switch the power of each of the continuously variable transmissions 11R and 11L after shifting to two high and low stages. or,
The boarding operation unit 6 is provided with a single sub-transmission lever 25 that can be rocked in the front-rear direction.
A gear type sub-transmission mechanism 13R, via an unillustrated linkage mechanism,
It is linked to 13L, and the power after shifting by each of the continuously variable transmissions 11R and 11L for traveling can be shifted to two high and low stages by operating the auxiliary transmission lever 25.

As shown in FIG. 4, the mission case 9
Is a two-divided structure that can be separated into left and right, and is equipped with left and right gear type auxiliary transmissions 13R, 13L, etc., and a side wall 17 on the left side thereof bulges outward to allow traveling. Each of the continuously variable transmissions 11R and 11L for operation and the continuously variable transmission 12 for work is formed to have a recessed portion 18. Each continuously variable transmission 11R for traveling, 1
1L is configured as a hydrostatic continuously variable transmission that includes an axial plunger type variable displacement piston pump 19 and a piston motor 20, respectively. The continuously variable transmission 12 for work is also similarly provided as an axial plunger type. It is configured as a hydrostatic stepless transmission including a variable displacement type piston pump 21 and a piston motor 22, and switches the traveling direction of each of the left and right crawler type traveling devices 1R, 1L to a forward direction and a backward direction, and a traveling speed. Is configured to be capable of continuously shifting gears. In addition, a port block 23 in which an oil passage connecting the piston pump 19 and the corresponding piston motor 20 and an oil passage connecting the piston pump 21 and the piston motor 22 are formed is provided on the left side wall. It is connected to 17 to close the recess 18.

That is, since the side wall 17 of the mission case 9 is effectively used for the casing of each continuously variable transmission 11R, 11L, 12, the number of parts and the manufacturing cost can be reduced, and the concave portion of the side wall 17 can be reduced. By configuring each continuously variable transmission 11R, 11L, 12 by using 18,
Since the continuously variable transmissions 11R, 11L, and 12 largely enter the inside of the mission case 9 and the space required for disposing them is reduced, the combine as a whole can be downsized. There is. 2 is a system diagram showing the transmission structure of the entire combine in the unfolded state, and FIG. 3 is a vertical cross-sectional side view showing the arrangement of a plurality of transmission shafts arranged inside the mission case 9, and FIG.
FIG. 4 is a vertical cross-sectional rear view showing a transmission mechanism arranged inside a mission case 9.

As shown in FIG. 5, the hydraulic traveling operation mechanism 30 for individually shifting the traveling continuously variable transmissions 11R and 11L, and the work continuously variable transmission 12 are operated for shifting. And a hydraulic operation mechanism 36 for operating each. The traveling operation mechanism 30 includes a pair of double-acting hydraulic cylinders 33R and 33L (actuators) which are interlockingly connected to the trunnion shaft 29 (an example of an operated body) of each of the traveling continuously variable transmissions 11R and 11L. Of the hydraulic cylinders 33R and 33L, and a pair of two-position switches that can be switched between a state in which hydraulic oil is supplied to a pair of oil chambers and a state in which the supply is stopped, which correspond to forward and reverse operations on these hydraulic cylinders 33R and 33L, respectively. Type oil supply solenoid valve 34A, and a pair of two-position switching type oil discharge solenoid valve 34B that can be switched between a state in which hydraulic oil is discharged from the pair of oil chambers and a state in which discharge is stopped. Has been done. Each of the hydraulic cylinders 33R and 33L is configured to be urged to return to the neutral position by the urging force of a spring incorporated therein.

Similarly, the work operating mechanism 36 is also interlocked with the trunnion shaft 37 of the continuously variable transmission 12 for work, and is urged to return to the neutral position by the urging force of the internal spring. Double-acting hydraulic cylinder 40
And a pair of two-position switching type refueling solenoid valves 41A that can be switched between a state in which hydraulic oil is supplied to a pair of oil chambers corresponding to forward and reverse operations on the hydraulic cylinder 40 and a state in which the supply is stopped. And a pair of two-position switching type oil discharge solenoid valves 41B that can be switched between a state in which the hydraulic oil is discharged from the pair of oil chambers and a state in which the discharge is stopped.

Each of the refueling solenoid valves 34A, 41A is constructed so as to urge the spool to move to the refueling stop state by the urging force of the spring, and the solenoid urges the spool against the urging force of the spring. It is configured to switch to a state in which hydraulic oil is supplied by moving operation, and each of the oil discharge solenoid valves 34B and 41B is configured to move and bias the spool to the discharging state by the biasing force of the spring. In this configuration, the solenoid is moved by the electromagnetic force of the solenoid against the biasing force of the spring to stop the discharge of the hydraulic fluid.

Continuously variable transmissions 11R, 11 as described above
If the shift operation of L is added, for example, as shown in FIG. 6, if the shift position of the trunnion shaft 29 is in the neutral position as the stop shift position, the shift output (running speed) becomes zero, and the trunnion shaft 29 moves. When the shift position is rotated from the neutral position in a predetermined direction, the traveling speed in the forward direction is continuously increased, and when the trunnion shaft 29 is rotated in the opposite direction from the neutral position. It is configured so that the traveling speed in the reverse direction is continuously increased.

The boarding operation unit 6 has a single main gearshift lever 24 as a vehicle speed command means capable of swinging over a predetermined front-rear operation range along the front-rear direction, and a predetermined left-right operation along the left-right direction. A single turning lever 26 as a turning command means capable of swinging over a range is provided. Then, as shown in FIG. 5, a speed change lever sensor 27 for detecting the operation position of the main speed change lever 24 and a turning lever sensor 28 as an operation position detecting means for detecting the operation position of the turning lever 26 are respectively provided. Both of them are composed of rotary potentiometers.

When the turning lever 26 is operated to the straight-ahead command position located approximately in the middle of the left-right operation range, the left and right crawler traveling devices 1R and 1L are driven at the same speed, and the straight-ahead traveling condition is reached. When a swing operation is performed in a turning command range located in either the left or right direction from the position, the turning travel is instructed so that the turning radius becomes smaller as it is operated toward the side farther from the straight-ahead command position in the turning command range. It is composed.

A pair of continuously variable transmissions 11R for traveling,
11L includes rotation speed sensors 44 and 45 as shift output detecting means for individually detecting the output rotation speeds thereof,
Gearshift position sensors 46R and 11L are provided with gearshift position sensors 46 and 47 as gearshift position detection means for detecting the gearshift positions of the continuously variable transmissions 11R and 11L, that is, the operating angles of the trunnion shafts 29 by the pair of hydraulic cylinders 33R and 33L. Has been.

Then, the hydraulic cylinders 33R, 33R
A control device 31 utilizing a microcomputer is provided as a control means for controlling the operations of L and 40, and this control device 31 causes the vehicle body to travel straight at a speed corresponding to the vehicle speed command information commanded by the vehicle speed command means. Therefore, a straight-ahead control for activating the pair of hydraulic cylinders 33R, 33L and a swing control for activating the pair of hydraulic cylinders 33R, 33L to perform the swing commanded by the swing command means are executed. .

More specifically, in the state where the turning lever 26 is operated to the straight-ahead command position and the straight-ahead command is issued, when the main speed change lever 24 is operated to the neutral position which is located in the middle of the operable range, the traveling is stopped. When the vehicle is swung from the neutral position to the forward side, the traveling speed to the forward side is continuously increased accordingly. The operation of the pair of hydraulic cylinders 33R and 33L is controlled so that the speed is increased steplessly. When the main transmission lever 24 is fixed at a predetermined position, a command is issued at that position. A pair of hydraulic cylinders 3 are used so that the vehicle body travels straight at the target traveling speed.
The straight ahead control for controlling the operations of the 3R and 33L is executed.

Further, when the main control lever 31 is operated to travel at a predetermined speed, the control device 31 swings the turning lever 26 from the straight-ahead command position to either the left or right turning command range. The turning control for controlling the operation of the traveling hydraulic cylinders 33R, 33L is executed so that the turning radius becomes smaller as the position is operated farther from the straight-ahead command position.

Next, a specific control operation of the turning control by the control device 31 will be described. In this turning control, the turning lever 26 is controlled so that the turning radius becomes smaller as the turning lever 26 is operated to the side farther from the straight-ahead command position within the turning command range. Basically, the relationship between the operating position of the turning lever 26 in the turning command range and the target turning state at the time of performing can be switched to three different turning modes.

More specifically, a three-contact mode changeover switch 42 for switching the above-described turning mode into three turning modes of a gentle turning mode, a land turning mode, and a super land turning mode is provided. Therefore, a switching command from the mode changeover switch 42 is given to the control device, and the control device 31 is configured to switch the turning mode as follows based on the switching command. In other words, in the gentle turning mode, the traveling speed of the crawler traveling device on the turning side is reduced to a speed lower than the traveling speed of the crawler traveling device on the opposite side to turn the vehicle body into a turning state. The deceleration amount when decelerating the traveling speed of the device from the traveling speed of the other traveling device is set to increase as the turning lever 26 moves away from the straight-ahead command position. Then, when the turning lever 26 is operated to the maximum operation position on the turning side, the traveling speed of the crawler traveling device on the turning side is reduced to about 1/3 of the traveling speed of the crawler traveling device on the opposite side. It turns into a turning state.

More specifically, as shown by a line L1 in FIG. 8, the traveling speed of the crawler traveling device on the side opposite to the turning side is kept constant at the target traveling speed commanded by the main shift lever 24. On the other hand, as indicated by the line L2, as the operation position of the turning lever 26 moves away from the straight-ahead command position toward the turning side, the running speed of the turning side crawler traveling device is gradually reduced, and the turning lever 26 reaches the maximum. When operated to the operating position, the left and right crawler traveling devices 1 with respect to the operating position of the turning lever 26 are decelerated to about 1/3 of the traveling speed V of the crawler traveling device on the opposite side.
The change characteristics of the speed ratio of R and 1L are preset.
The speed ratio corresponding to the operating position of the turning lever 26 is determined from the characteristic of the speed ratio and the detected value of the shift position of the trunnion shaft of the continuously variable transmission with respect to the crawler traveling device on the side opposite to the turning side at that time. So that the target shift position of the trunnion shaft of the continuously variable transmission with respect to the crawler traveling device on the turning side is determined, and the shift position of the trunnion shaft detected by the shift position sensor becomes the target shift position, The corresponding hydraulic cylinder 33 is controlled.

Next, in the solid turning mode, the traveling speed of the crawler traveling device on the turning side is made slower than the traveling speed of the crawler traveling device on the opposite side to turn the vehicle body, and further, the crawler traveling on the turning side is performed. This is the same as the gentle turning mode in that the deceleration amount when decelerating the traveling speed of the device from the traveling speed of the other crawler traveling device is set to increase as the turning lever 26 moves away from the straight-ahead command position. However, in this trusted turning mode, when the turning lever 26 is operated to the maximum operation position, the running speed of the crawler running device on the turning side becomes zero and the running is stopped. Moreover, at this time, the crawler traveling device on the turning side is configured to be braked by a braking mechanism (not shown).

More specifically, as indicated by a line L3 in FIG. 8, the traveling speed of the crawler traveling device on the slewing side is gradually reduced as the operating position of the slewing lever 26 moves away from the straight ahead command position to the slewing side. When the turning lever 26 is operated to the maximum operating position, the left and right crawler running devices 1 with respect to the operating position of the turning lever 26 are decelerated until the running speed of the turning side crawler running device becomes zero.
R and 1L speed ratios are preset. The speed ratio corresponding to the operating position of the turning lever 26 is determined from the characteristic of the speed ratio and the detected value of the shift position of the trunnion shaft of the continuously variable transmission with respect to the crawler traveling device on the side opposite to the turning side at that time. So that the target shift position of the trunnion shaft of the continuously variable transmission with respect to the crawler traveling device on the turning side is determined, and the shift position of the trunnion shaft detected by the shift position sensor becomes the target shift position, The corresponding hydraulic cylinder 33 is controlled.

In the super-trust turning mode, the amount of deceleration when the running speed of the crawler running device on the turning side is reduced from the running speed of the other crawler running device is as the turning lever 26 moves away from the straight-ahead command position. In the turning state in which the vehicle body is turned by reducing the traveling speed of the crawler traveling device on the turning side from the traveling speed of the crawler traveling device on the opposite side by setting it to a larger form, and the traveling speed of the crawler traveling device on the turning side. The point is the same as in the pivot turning mode, in which the vehicle is decelerated to zero and stops traveling, but in this super-tip turning mode, the turning device on the turning side moves on the other traveling device. It is configured to switch to a turning state in which the vehicle travels in a direction opposite to the direction, and it is possible to turn with a smaller turning radius.

More specifically, as indicated by a line L4 in FIG. 8, in the first turning state, the crawler traveling device on the turning side becomes farther as the operation position of the turning lever 26 deviates from the straight-ahead command position to the turning side. When the turning speed is gradually reduced and the turning lever 26 is operated to a predetermined operation position on the way, the second turning state is set and the running speed of the crawler running device on the turning side becomes zero. When it is operated further to the turning side than the predetermined operation position, it switches to the third turning state, and the running speed when the turning side crawler running device is run in a direction opposite to the running direction of the other crawler running device, The speed ratio of the left and right crawler traveling devices to the operating position of the turning lever 26 is set in advance so that the turning lever 26 becomes larger as it moves away from the straight-ahead command position. It is constant.

Then, from the characteristic of this speed ratio and the detected value of the shift position of the trunnion shaft of the continuously variable transmission with respect to the crawler traveling device on the side opposite to the turning side at that time, the operation position of the turning lever 26 is corresponded. The speed change ratio of the trunnion shaft of the continuously variable transmission with respect to the crawler traveling device on the turning side is determined, and the shift position of the trunnion shaft detected by the shift position sensor becomes the target shift position. Thus, the corresponding hydraulic cylinder 33 is controlled.

That is, by the control operation of the control device 31 based on the switching operation of the mode changeover switch 42, the turning mode can be switched to the turning mode in which a desired turning state can be expressed. Further, in any turning state, the drive speed of the crawler type traveling device 1 on the side opposite to the turning side is kept constant while maintaining the target traveling speed commanded by the main speed change lever 24, and the crawler type on the turning side is maintained. By changing the drive speed of the traveling device 1 as described above, the machine body can be smoothly turned.

Next, the straight ahead control will be described. The control device 31 is configured to execute the following processes as the straight ahead control. That is, when the main speed change lever 24 is operated to the neutral position (stop command position), it becomes the neutral position as the stop speed change position, and when the main speed change lever 24 is operated to move from the neutral position, the movement operation amount is large. Accordingly, the target shift positions of the pair of left and right trunnion shafts 29 corresponding to the commanded positions are set so that the speed changes to the high speed side and the shift position becomes the upper limit shift position when the upper limit value of the predetermined operation range is commanded. Target shift position setting process, pair of trunnion shafts 2 detected by pair of shift position sensors 46, 47
So that each of the shift positions 9 and 29 becomes the target shift position,
The trunnion shaft 2 in the continuously variable transmission of at least one of the pair of continuously variable transmissions 11R and 11L is executed by executing the gearshift position adjustment processing for operating the pair of hydraulic cylinders 33R, 33L and the gearshift position adjustment processing.
When the shift position of 9 reaches the control state switching position defined in relation to the target shift position, the pair of continuously variable transmissions 11
So that the output speed of R and 11L becomes the target speed for synchronization,
Each of the speed synchronization processes for operating the pair of hydraulic cylinders 33R, 33L is configured to be executed based on the detection information of the pair of rotation speed sensors 44, 45.
In this embodiment, the control state switching position is set to the target shift position.

As the speed synchronizing process, one of the pair of continuously variable transmissions 11R and 11L is defined as a reference continuously variable transmission, and the reference continuously variable transmission is provided. The hydraulic cylinder (33R or 33L) corresponding to the continuously variable transmission is operated so as to maintain the gearshift position of the trunnion shaft 29 at the position, and the output speed of the reference continuously variable transmission is rotated. The rotation speed sensor (4) detects the speed sensor (44 or 45) and sets it as the synchronization target speed so that the output speed of the other continuously variable transmission becomes the synchronization target speed.
4 or 45), the hydraulic cylinder (33R or 33L) corresponding to the other continuously variable transmission is operated based on the detected information.

Further, in the speed synchronizing process, the shift position adjusting process is executed so that the shift position of the trunnion shaft 29 in one of the pair of continuously variable transmissions 11R and 11L is in the control state. At the switching position, the trunnion shaft 29 of the pair of continuously variable transmissions is selected.
The continuously variable transmission whose shift position is located farther from the neutral position as the stop shift position is defined as the reference continuously variable transmission.

More specifically, as shown in FIG.
Each of the left and right continuously variable transmissions 11R and 11L for traveling with respect to the operation position of the main transmission lever 24 in the straight traveling state.
The target gear shift positions of the trunnion shafts 29, 29 are preset and stored. Then, as shown in FIG. 9, the control device 31 sets the target shift position at that time based on the detection result of the operation position of the main shift lever 24 detected by the shift lever sensor 27 (step 1, 2). This corresponds to the target shift position setting process. Here, as is apparent from FIGS. 6 and 7, when the main shift lever 24 is operated to the neutral position, the shift output becomes zero, and when the main shift lever 24 is moved from the neutral position, the movement operation amount increases as the shift operation amount increases. The trunnion shaft 29 so that the upper limit shift position is reached when the upper limit value of the predetermined operation range is commanded.
The target shift positions of 29 are set.

Next, the operation of the solenoid valves 34A, 34B is controlled so that the gear shift positions of the trunnion shafts 29, 29 detected by the gear shift position sensors 46, 47 become the target gear shift positions. For each hydraulic cylinder 33R, 33L
The shift operation for activating is executed (step 3). That is, the position feedback control based on the shift position detection information is executed. The shift operation at this time corresponds to the shift position adjusting process. Therefore, when the main gear shift lever 24 is operated from the neutral position to the forward drive side, the vehicle travels straight forward in the forward direction in a state where the speed increases as the operation amount from the neutral position increases, and the main gear shift lever 24 moves to the reverse drive side. When the vehicle is operated in the forward direction, the vehicle travels straight in the backward direction in a state where the speed increases as the operation amount from the neutral position increases, and the forward / backward movement is performed by the control operation of the control device 31 based on the operation of the main transmission lever 24. It is possible to perform the switching and the stepless speed change operation, so that the forward straight traveling state and the backward straight traveling state at a desired speed can be easily revealed.

By executing the shift position adjusting process as described above, the shift position of the trunnion shaft 29 of one of the left and right continuously variable transmissions 11R and 11L is set as the target for the control state switching position. When the shift position is reached, in other words, when the shift position of the trunnion shaft 29 of the left and right continuously variable transmissions is far from the neutral position, the shift position of the left and right continuously variable transmissions is far from the neutral position. The continuously variable transmission located on the side is defined as the reference continuously variable transmission, and the output speed of the reference continuously variable transmission is detected by the rotation speed sensor (44 or 45) to obtain the synchronization target speed. To the target rotation speed (steps 5 and 6)

Then, the hydraulic cylinder corresponding to the continuously variable transmission is operated so that the gear shift position of the trunnion shaft 29 in the reference continuously variable transmission is maintained at that position, and the other continuously variable transmission is operated. Based on the detection information of the rotation speed sensor (44 or 45), a gear shift operation for operating the hydraulic cylinder corresponding to the other continuously variable transmission is executed so that the output speed of the device becomes the target rotation speed (step). 7, 8). That is, the speed feedback control is executed based on the detection result of the output speed of the continuously variable transmission. Such processing corresponds to speed synchronization processing.

The speed synchronizing process is performed until the command position of the main speed change lever 24 is changed, and when the command position of the main speed change lever 24 is changed, the process returns to step 1, and the target speed change position setting process and the speed change process are performed again. After the position adjustment processing is executed, the speed synchronization processing is executed.

[Second Embodiment] Next, a second embodiment of the turning control apparatus for a work vehicle according to the present invention will be described. In this embodiment, in the straight ahead control by the control device,
Since the configuration other than the configuration for executing the speed synchronization processing is the same as that of the first embodiment, only the configuration different from that of the first embodiment will be described, and the description of the same configuration will be omitted.

In the first embodiment, in the speed synchronization process, the pair of continuously variable transmissions 11R and 11R are always used.
An example is shown in which the continuously variable transmission in which the shift position of the trunnion shaft 29 is located farther from the stop shift position (neutral position) is defined as the reference continuously variable transmission in L. Instead of the configuration, the configuration is as follows. That is, the control device as the control means controls the pair of continuously variable transmissions when the gear shift position of the operated body in one of the continuously variable transmissions reaches the control state switching position. When the gear shift position of the operated body in one of the continuously variable transmissions is located on the lower speed side than the set position, the gear shift position of the operated body of the pair of continuously variable transmissions is selected. Defines the continuously variable transmission located on the side far from the stop gear position as the reference continuously variable transmission, and the gear shift positions of the operated bodies of the pair of continuously variable transmissions are both greater than the set position. When located on the high speed side, the continuously variable transmission of the pair of continuously variable transmissions, which is closer to the stop shifting position of the operated body, is used as the continuously variable transmission on the reference side. It is a configuration defined as a device.

More specifically, the control device 31
However, when the shift position of the trunnion shaft 29 in either one of the pair of continuously variable transmissions 11R and 11L becomes the control state switching position, the pair of continuously variable transmissions 11R and 11R, When the gearshift position of the trunnion shaft 29 in one of the 11L continuously variable transmissions is located on the lower speed side than the set position, the gearshift position of the trunnion shaft 29 of the pair of continuously variable transmissions is the stop gearshift. The continuously variable transmission located farther from the position (neutral position) is defined as the reference continuously variable transmission. When the gear shift positions of the trunnion shafts 29 of the pair of continuously variable transmissions 11R and 11L are both on the higher speed side than the set position, the gear shift of the trunnion shaft 29 of the pair of continuously variable transmissions is performed. The continuously variable transmission whose position is close to the stop shifting position (neutral position) is defined as the reference continuously variable transmission.

[Third Embodiment] Next, a third embodiment of the turning control apparatus for a work vehicle according to the present invention will be described. In this embodiment, in the straight ahead control by the control device,
Since the configuration other than the configuration for executing the speed synchronization processing is the same as that of the first embodiment, only the configuration different from that of the first embodiment will be described, and the description of the same configuration will be omitted.

In the first embodiment, in the speed synchronizing process, the pair of continuously variable transmissions 11R and 11R are always used.
An example is shown in which the continuously variable transmission in which the shift position of the trunnion shaft 29 is located farther from the stop shift position (neutral position) is defined as the reference continuously variable transmission in L. Instead of the configuration, the configuration is as follows. That is, the control device as the control means executes the shift position adjustment process so that the shift position of the operated body in one of the continuously variable transmissions of the pair of continuously variable transmissions is the control state switching position. In this case, the continuously variable transmission is defined as the reference continuously variable transmission.

More specifically, the control device 31
However, when the gear shift position of the trunnion shaft 29 in any one of the pair of continuously variable transmissions becomes the control state switching position by the execution of the gear shift position adjustment processing, the trunnion shaft is changed. The continuously variable transmission whose number 29 is the control state switching position is defined as the reference side continuously variable transmission.

[Fourth Embodiment] Next, a fourth embodiment of the turning control apparatus for a working vehicle according to the present invention will be described. This embodiment is the same as the first embodiment except for the configuration for executing the speed synchronization processing in the straight ahead control by the control device, and therefore only the configuration different from the first embodiment will be described. However, description of the same configuration is omitted.

In the first embodiment, as the speed synchronizing process, the hydraulic cylinder corresponding to the continuously variable transmission is operated so as to hold the gear shift position of the trunnion shaft in the reference continuously variable transmission at that position. Further, the output speed of the continuously variable transmission on the reference side is set as the synchronization target speed, and the rotation speed sensor detects so that the output speed of the other continuously variable transmission becomes the synchronization target speed. Although the hydraulic cylinder corresponding to the other continuously variable transmission is operated based on the information, in the fourth embodiment,
Instead of maintaining the speed of one continuously variable transmission and performing speed feedback control only on the other side, the pair of left and right continuously variable transmissions are both subjected to speed feedback control.

That is, in the speed synchronization processing, specifically, step 7 of the control flowchart of FIG. 9 in the first embodiment, control is executed as follows. The output speed of the continuously variable transmission set as the reference side continuously variable transmission is detected by the rotation speed sensor, and the detected value is set as the target rotation speed.
The configuration is such that the pair of hydraulic cylinders 33R and 33L are controlled to operate so that the detected values of 4 and 45 both reach the target speed. Then, such speed synchronization processing is performed until the command position of the main transmission lever 24 is changed. In this way, the left and right continuously variable transmissions are both subjected to speed feedback control until the command position of the main transmission lever 24 changes.

[Fifth Embodiment] Next, a fifth embodiment of the turning control apparatus for a work vehicle according to the present invention will be described. This embodiment is the same as the first embodiment except for the configuration for executing the straight ahead control by the control device, so only the configuration different from the first embodiment will be described and the same configuration will be described. The description is omitted.

That is, in this embodiment, the control device performs, as the straight ahead control, the same target shift position setting process as the target shift position setting process in the first embodiment and the following shift operation process. Is configured to always run. Explaining the shift operation process, one of the pair of continuously variable transmissions is set as the main transmission side, and the other continuously variable transmission is set as the follow-up side. The actuator (hydraulic cylinder) corresponding to the continuously variable transmission is operated so that the gear shift position of the operated body of the apparatus approaches the target gear shift position, and the output speed of the continuously variable transmission on the main gear shift side is adjusted. Based on the detection information of the shift output detection means (rotational speed sensor), the tracking side continuously variable speed is set so that the output speed of the continuously variable transmission on the tracking side becomes the tracking target speed. Actuate the actuator (hydraulic cylinder) corresponding to the transmission.

In addition, the continuously variable shift set on the main shift side is not used, as in the first embodiment, the shift positions of the pair of operated bodies are not controlled so as to approach the target shift position. The device always performs control (position feedback control) so that the gear shift position of the operated body approaches the target gear shift position, and the output speed of the continuously variable transmission on the tracking side is always the tracking target speed. Is controlled (speed feedback control). Specifically, FIG.
0, the same target shift position setting process (step 1) as the target shift position setting process in the first embodiment described above.
1) and 12) are executed, and only the continuously variable transmission set as the main shift side is controlled (position feedback control) so that the shift position of the operated body approaches the target shift position (step 13). The output speed of the continuously variable transmission set as the shift side is detected, and that speed is set as the following target speed for tracking (steps 14 and 15), and only the continuously variable transmission on the following side has the output speed for the above tracking. A gear shift operation (speed feedback control) is performed so as to reach the target speed (step 16).

In this embodiment, the continuously variable transmission set as the main transmission side of the left and right continuously variable transmissions may be configured so as to be kept constant from the start of the mowing operation to the end of the operation. You may make it change suitably according to a work situation.

[Sixth Embodiment] Next, a sixth embodiment of the turning control apparatus for a work vehicle according to the present invention will be described with reference to the drawings.

As shown in FIG. 11, in this embodiment,
The shift position sensors 46 and 47 in the first embodiment are not provided, and instead, an engine rotation sensor 50 as an engine output detection unit that detects the output rotation speed of the engine, and the pair of continuously variable transmissions. An auxiliary shift sensor 51 is provided as a shift state detecting means for detecting a shift state of sub transmissions 13R and 13L provided in a transmission mechanism from the device to the pair of traveling devices. The subtransmission sensor 51 is configured to detect whether it is a high speed or a low speed based on the operation state of the subtransmission lever 25.

Then, the control device 31 performs the straight-ahead control based on the detection information of the engine rotation sensor 50 and the auxiliary transmission sensor 51, and the pair of continuously variable transmissions 11R and 11R.
An upper limit vehicle speed setting process for obtaining an upper limit vehicle speed that can be changed by L
When the main speed change lever 24 serving as the vehicle speed command means is operated to the stop command position, the main speed change lever 24 is brought into a stopped state. And a target vehicle speed setting process for setting the target traveling speed of the vehicle body corresponding to the command position so that the upper limit vehicle speed becomes the upper limit vehicle speed when the upper limit value of the predetermined operation range is commanded, and a pair of rotation speeds. Sensor 44,
A pair of continuously variable transmissions 11R and 11L detected at 45
Each of the output adjustment processing for operating the pair of hydraulic cylinders 33R, 33L is executed so that the output speed in each of the above becomes the target traveling speed.

Although not described in detail, the rotation speed sensors 44 and 45 can detect the absolute value of the output rotation speed of the pair of continuously variable transmissions 11R and 11L by counting the generated pulse signals. In addition to that, for example, the direction of rotation of the continuously variable transmission by the phase difference of the pulse waveform,
That is, it is also configured to be able to detect whether it is the forward direction or the backward direction.

A specific control operation of the control device 31 will be described with reference to FIG. The control device 31 first detects the output rotation speed of the engine 7 based on the detection information of the engine rotation sensor 50 (step 21). Then, with reference to the detection result of the auxiliary shift sensor 51, the pair of continuously variable transmissions 11R and 1R at the output rotation speed are output.
The upper limit vehicle speed at which gear shifting is possible in 1 L is calculated (step 22). That is, the upper limit vehicle speed that can be changed by the continuously variable transmissions 11R and 11L from the output rotational speed of the engine 7 at that time is obtained from preset mechanical characteristics. This process corresponds to the upper limit vehicle speed setting process.

When the upper limit vehicle speed is obtained in this way,
As shown in FIG. 12, when the main shift lever 24 is moved from the neutral position based on the upper limit vehicle speed, the main shift lever 24 changes to the higher speed side as the moving operation amount increases, and within the predetermined operation range. The change characteristic of the target traveling speed of the vehicle body is determined so as to change linearly with respect to the change of the command position so that the upper limit vehicle speed becomes the upper limit vehicle speed when the upper limit value is commanded. At this time, the higher the engine output is, the larger the rate of change of the target traveling speed with respect to the change of the command position (the inclination angle in FIG. 12) is. Become.

Explaining based on a concrete example with reference to FIG. 12, when the output rotation speed of the engine 7 is the highest, the change characteristic of the target traveling speed is set as shown by the line L5 in FIG. The upper limit vehicle speed V11 is set when the upper limit value on the forward side of the predetermined operation range is instructed, and the upper limit vehicle speed V1 is set when the upper limit value on the reverse side is instructed.
2 is set. If the output rotation speed of the engine 7 is the lowest, the change characteristic of the target traveling speed is set as shown by the line L6 in FIG. 12, and the upper limit value on the forward side of the predetermined operation range is commanded. Sometimes upper limit vehicle speed V21
Is set and the upper limit value on the reverse side is commanded, the upper limit vehicle speed V22 is set. If the output rotation speed of the engine 7 is an intermediate value, an intermediate characteristic between the line L5 and the line L6 is set.

Next, the operation position of the main speed change lever 24 is detected, and based on the change characteristic set as described above and the detection result of the operation position of the main speed change lever 24, the target travel at that time is performed. Set the speed (steps 23, 2)
4). This process corresponds to the target vehicle speed setting process.

Then, a pair of left and right continuously variable transmissions 11R,
A gear shift operation is performed to operate the pair of hydraulic cylinders 33R and 33L so that the detection values of the rotation speed sensors 44 and 45 in 11L respectively become the target rotation speed (step 25). That is, the feedback control based on the detection result of the output rotation speed is executed. This shift operation corresponds to the output adjustment processing.

[Other Embodiments] Other embodiments of the present invention will be listed below.

(1) In the first embodiment, in the speed synchronizing process, the pair of continuously variable transmissions 11 are always provided.
Of the R and 11L, the continuously variable transmission whose shift position of the trunnion shaft 29 is located farther from the stop shift position (neutral position) is defined as the reference continuously variable transmission. Instead of such a configuration, the configuration described in the following (a) and (b) may be adopted.

(A) In the speed synchronization processing,
Of the pair of continuously variable transmissions 11R and 11L, the continuously variable transmission whose gear shift position of the trunnion shaft 29 is closer to the stop gear shift position (neutral position) is defined as the reference continuously variable transmission. .

(B) When the gear shift position of the trunnion shaft 29 in any one of the pair of continuously variable transmissions becomes the control state switching position by the execution of the gear shift position adjustment processing. The continuously variable transmission whose shift position of the trunnion shaft 29 is the control state switching position is determined as the reference continuously variable transmission.

(2) In the first embodiment, in the speed synchronizing process, the pair of continuously variable transmissions 11R and 11R are used.
Although it is determined that the shift position of the trunnion shaft 29 in one of the continuously variable transmissions of L has reached the target shift position, instead of such a configuration, the shift position is set with respect to the target shift position. It may be determined that the position is on the front side of the operator in the moving direction by the amount, and the pair of continuously variable transmissions 11
It may be determined that both R and 11L have reached the target shift position.

In the first embodiment, the output speed of the continuously variable transmission on the reference side is set as the target speed for synchronization. The output speed of the device may be used, or the average value of the output speeds of a pair of continuously variable transmissions may be used. It can be implemented in various forms such as using the obtained target speed.

(3) In each of the above-mentioned embodiments, a plurality of two-position switching type solenoid valves are provided as the structure for hydraulically controlling the hydraulic cylinder as the actuator, but the present invention is not limited to such a structure. The following configuration may be adopted. For example, as shown in FIG. 14, a three-position switching type electromagnetic switching valve 52 that switches the supply state of the hydraulic oil to the hydraulic cylinder 33R and a two-stage switching oil discharge state.
The present invention can be implemented in various forms, such as being composed of two 2-position switching type electromagnetic switching valves 53. Although only the hydraulic cylinder 33R is shown in FIG. 14, the other hydraulic cylinder 3R is shown.
The same applies to 3L.

(4) In each of the above embodiments, the hydraulic cylinder is illustrated as an actuator for operating the trunnion shaft of the continuously variable transmission, but other actuators such as a hydraulic motor or an electric motor may be used as the actuator.

(5) In each of the above embodiments, the hydrostatic continuously variable transmission is used as the pair of continuously variable transmissions. However, instead of such a configuration, for example, a belt type continuously variable transmission or a taper cone is used. A continuously variable transmission of the type may be combined with a forward / reverse switching mechanism for switching the traveling direction back and forth. Further, in combination with such a configuration, the vehicle speed command means is configured such that one end side of the predetermined operation range is a stop command position for instructing a travel stop and the other end side of the predetermined operation range is an upper limit value on the high speed side. You can do it.

(6) In each of the above-mentioned embodiments, the combine vehicle is exemplified as the work vehicle, but the present invention is not limited to the combine harvester, and other agricultural work vehicles such as a carrot harvester and a radish harvester may be used. Alternatively, a work vehicle such as a construction machine may be used.

[Brief description of drawings]

1] Overall side view of combine

FIG. 2 is a schematic vertical sectional rear view showing a transmission structure.

FIG. 3 is a schematic vertical sectional side view showing a transmission structure.

FIG. 4 is a longitudinal rear view showing the transmission structure.

FIG. 5 is a schematic diagram showing a configuration of an operation structure.

FIG. 6 is a diagram showing a relationship between a shift position and traveling speed.

FIG. 7 is a diagram showing a relationship between a main shift lever position and a target shift position.

FIG. 8 is a diagram showing the relationship between the turning lever position and the speed ratio of the left and right traveling devices.

FIG. 9 is a flowchart of control operation

FIG. 10 is a flowchart of the control operation of the fifth embodiment.

FIG. 11 is a schematic diagram showing a configuration of an operation structure according to a sixth embodiment.

FIG. 12 is a diagram showing a relationship between a main shift lever position and a target speed according to the sixth embodiment.

FIG. 13 is a flowchart of the control operation of the sixth embodiment.

FIG. 14 is a hydraulic circuit diagram of another embodiment.

[Explanation of symbols]

1R, 1L traveling device 7 engine 11R, 11L continuously variable transmission 24 vehicle speed command means 26 Turning command means 29 Operated body 31 Control means 33R, 33L actuator 44, 45 Shift output detection means 46, 47 Shift position detecting means 50 Engine output detection means 51 Gear shift state detecting means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) A01D 69/03 A01D 69/03 B62D 11/04 B62D 11/04 G (72) Inventor Shigeki Hayashi Sakai, Osaka 64, Ishizukitamachi, Ichizu, Japan (72) Inventor, Yuji Kato 64, Ishizukitamachi, Sakai, Osaka EC17 EC18 ED01 ED27 3D052 AA01 AA02 BB08 BB11 DD01 DD04 EE01 FF02 GG04 HH03 JJ21 3J053 AA03 AB03 AB12 AB23 AB33 AB34 DA01 DA06 DA22 DA23 EA02 EA04 FA02 FA03 FB06 FC02 FC03

Claims (9)

[Claims] 1. A pair of continuously variable transmissions for continuously changing the traveling speed of a pair of left and right traveling devices driven by the power of an engine, and a pair of continuously variable transmissions for individually shifting gears. A pair of actuators, a vehicle speed command means for freely moving within a predetermined operation range including a stop command position for commanding travel stop, and commanding a higher speed as the movement operation amount from the stop command position increases, and a command for turning. Turning command means, a straight-ahead control for operating the pair of actuators to move the vehicle body straight at a speed corresponding to the vehicle speed command information commanded by the vehicle speed command means, and a command issued by the turning command means. A traveling control device for a work vehicle, comprising: a control unit that executes a turning control for operating the pair of actuators to perform a turning, wherein the pair of stepless variable A pair of gear shift position detecting means for individually detecting the gear shift position of the gear-shifted operated body in each device, and a pair of gear shift output detecting means for separately detecting the output speed of the pair of continuously variable transmissions are provided. When the vehicle speed command means is operated to a stop command position as the straight ahead control, the control means is brought to a stop shift position, and when the vehicle speed command means is operated to move from the stop command position, the moving operation is performed. The target shift position of the pair of operated objects corresponding to the command position is changed so as to increase toward the high speed side and becomes the upper limit shift position when the upper limit value of the predetermined operation range is commanded. Target shift position setting process for setting the target shift position, and operating the pair of actuators so that the shift positions of the pair of operated bodies detected by the pair of shift position detecting means approach the target shift position. And a shift position adjusting process that causes the shift position of the operated body in at least one of the pair of continuously variable transmissions to be related to the target shift position. When the determined control state switching position is reached, the pair of actuators are operated based on the detection information of the pair of shift output detection means so that the output speed of the pair of continuously variable transmissions becomes the target speed for synchronization. A travel control device for a work vehicle configured to execute each of the speed synchronization processes. 2. The traveling control device for a work vehicle according to claim 1, wherein the control state switching position is set to the target shift position. 3. The control means determines one of the pair of continuously variable transmissions as a reference side continuously variable transmission as the speed synchronization processing, and sets the reference side continuously variable transmission as the continuously variable transmission. The actuator corresponding to the continuously variable transmission is operated so as to maintain the gear shift position of the operated body in the transmission, and the output speed of the continuously variable transmission on the reference side is used for the synchronization. The actuator corresponding to the other continuously variable transmission based on the detection information of the shift output detection means, so that the output speed of the other continuously variable transmission becomes the target speed for synchronization, which is set as the target speed. The traveling control device for a work vehicle according to claim 1 or 2, which is configured to operate. 4. The shift position of the operated body in one of the continuously variable transmissions of the pair of continuously variable transmissions is set to the control state switching position by the control means executing the shift position adjustment processing. In this case, the travel control device for a work vehicle according to claim 3, wherein the continuously variable transmission is configured as the reference side continuously variable transmission. 5. The shift position of the operated body in one of the continuously variable transmissions of the pair of continuously variable transmissions is set to the control state switching position by the control means executing the shift position adjustment process. In this case, the continuously variable transmission of the pair of continuously variable transmissions, in which the gear shift position of the operated body is located farther from the stop gear shift position, is defined as the reference side continuously variable transmission. Item 3. A traveling control device for a work vehicle according to item 3. 6. The pair of continuously variable transmissions when the control unit shifts the gear shift position of the operated body in one of the continuously variable transmissions to the control state switching position. When the gear shift position of the operated body in one of the continuously variable transmissions is located on the lower speed side than the set position, the gear shift position of the operated body of the pair of continuously variable transmissions is The continuously variable transmission located on the side far from the stop gear position is defined as the reference continuously variable transmission, and the gear shift positions of the operated bodies of the pair of continuously variable transmissions are both higher than the set position. Of the pair of continuously variable transmissions, the continuously variable transmission that is located closer to the stop gear shift position of the operated body is the continuously variable transmission of the reference side. It is configured to be defined as The traveling control device for the work vehicle described. 7. A pair of continuously variable transmissions for continuously shifting the traveling speeds of a pair of left and right traveling devices driven by the power of an engine, and a pair of continuously variable transmissions for individually shifting gears. A pair of actuators, a vehicle speed command means for freely moving within a predetermined operation range including a stop command position for commanding travel stop, and commanding a higher speed as the operation amount from the stop command position increases, and a command for turning. Turning command means, a straight ahead control for operating the pair of actuators to drive the vehicle body straight ahead at a speed corresponding to the vehicle speed command information instructed by the vehicle speed command means, and a command issued by the turning command means. A traveling control device for a work vehicle, comprising: a control unit that executes a turning control for operating the pair of actuators to perform a turning operation. An engine output detecting means for detecting a rotation speed; a pair of shift output detecting means for detecting an output speed of each of the pair of continuously variable transmissions; and a transmission from the pair of continuously variable transmissions to the pair of traveling devices. A shift state detecting means for detecting a shift state of an auxiliary transmission provided in the mechanism, and the control means performs the straight-ahead control based on detection information of the engine output detecting means and the shift state detecting means. An upper limit vehicle speed setting process for obtaining an upper limit vehicle speed that can be shifted by the pair of continuously variable transmissions, and when the vehicle speed command means is operated to a stop command position, the vehicle is in a stopped state, When a moving operation is performed, the moving operation amount changes to a higher speed side with an increase in the moving operation amount, and when the upper limit value of the predetermined operation range is commanded, the vehicle speed becomes the upper limit vehicle speed. A target output setting process of setting a target output speed corresponding to the command position, and an output speed of each of the pair of continuously variable transmissions detected by the pair of shift output detecting means become the target output speed. And a traveling control device for a work vehicle configured to execute each of the output adjustment processes for operating the pair of actuators. 8. A pair of continuously variable transmissions for continuously changing the traveling speeds of a pair of left and right traveling devices driven by the power of an engine, and a pair of continuously variable transmissions for individually shifting gears. A pair of actuators, a vehicle speed command means for freely moving within a predetermined operation range including a stop command position for commanding travel stop, and commanding a higher speed as the movement operation amount from the stop command position increases, and a command for turning. Turning command means, a straight ahead control for operating the pair of actuators to drive the vehicle body straight ahead at a speed corresponding to the vehicle speed command information instructed by the vehicle speed command means, and the turning command means A traveling control device for a work vehicle, comprising: a control unit that executes a turning control for operating the pair of actuators to perform a turning, wherein the pair of stepless variable A pair of gear shift position detecting means for individually detecting the gear shift position of the gear-shifted operated body in each device, and a pair of gear shift output detecting means for separately detecting the output speed of the pair of continuously variable transmissions are provided. When the vehicle speed command means is operated to a stop command position as the straight ahead control, the control means is brought to a stop shift position, and when the vehicle speed command means is operated to move from the stop command position, the moving operation is performed. The target shift position of the operated body corresponding to the command position is set so that it changes to the higher speed side as the amount increases and becomes the upper limit shift position when the upper limit value of the predetermined operation range is commanded. Target shift position setting process, and one of the pair of continuously variable transmissions is set as the main transmission side, and the other continuously variable transmission is set as the following side, and the continuously variable transmission of the main transmission side is set. The transmission cover The actuator corresponding to the continuously variable transmission is operated so that the gear shift position of the work approaches the target gear shift position, and the output speed of the continuously variable transmission on the main gear shift side is set as the following target speed for tracking. Shift operation for operating the actuator corresponding to the tracking side continuously variable transmission based on the detection information of the shift output detection means so that the output speed of the side continuously variable transmission becomes the tracking target speed. A travel control device for a work vehicle configured to constantly perform each of the processes. 9. The traveling control device for a work vehicle according to claim 1, wherein each of the pair of continuously variable transmissions is formed of a hydrostatic continuously variable transmission.