JPH1148809A - Work vehicle travel control device - Google Patents

Abstract

(57) [Summary] [Problem] When the front wheels are steered, when the vehicle is traveling at a low speed, a small turning control is performed in which the front wheels are driven at a higher speed than the rear wheels and a brake is applied to the rear wheels inside the turning. ,
When the vehicle is traveling at a high speed, the vehicle can be stably turned regardless of a speed change in a work vehicle whose small turning control is restrained. When a front wheel is steered beyond a set turning angle, a turning control means turns on a front wheel speed increasing device and body steering brakes. When the aircraft is traveling at a speed higher than the set speed, the restraining means 45 restrains the small turning control by the turning control means 44. When the front wheel 1 reaches the set turning angle, the maintenance control means 46 stores the state of the restraint means 45 at that time. While the front wheel 1 is at or above the set turning angle, the maintenance control means 46
6 in a stored state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a traveling steerable wheel located at one of the front and rear ends of an airframe and a non-steerable traveling wheel located at the other end. When the steering operation is performed beyond the set turning angle, the driving state of the steered wheels becomes the same or almost the same as that of the non-steered wheels, and the driving speed of the steered wheels becomes greater than that of the non-steered wheels. A turning control means for automatically switching the front wheel speed increasing device, which can be switched to an entering state at high speed, to the entering side to turn the aircraft in a small turn, or a steerable wheel is steered beyond a set turning angle. Then, the front wheel speed increasing device and the fuselage steering brake acting on the non-steering wheel inside the turning of the pair of left and right non-steering wheels are automatically switched to the entrance side to operate the aircraft. Turn control means to make a small turn, or steer the steerable wheels beyond the set turning angle A first turning control mode for automatically switching the front wheel speed increasing device and the body steering brake acting on the non-steered wheels inside the turning to the inward side to turn the body in a small turn; When the steering wheel is steered beyond the set turning angle, only the front wheel speed increasing device and the front wheel speed increasing device of the fuselage steering brake are automatically switched to the entrance side to make a small turn. The present invention relates to a traveling control device for a work vehicle including a turning control means that can be switched to a second turning control mode to be operated.

[0002]

2. Description of the Related Art The above-mentioned work vehicle can be easily operated simply by steering a steerable wheel by the operation of a turning control means when turning the body such as making a U-turn turn at an end of a field. The turning wheel can be turned with a smaller turning radius than turning while driving the die wheel and the non-steering wheel at the same or almost the same driving speed as in the case of going straight. Conventionally, in this type of working vehicle, for example, Japanese Unexamined Patent Publication No.
No. 62332 was disclosed. That is,
A standard drive state in which the drive speeds of the front and rear wheels are substantially equal,
The front cylinder is equipped with a front wheel transmission that can be switched by a hydraulic cylinder to a speed-up drive state in which the front wheel drive speed is higher than that of the rear wheel. The front wheel is steered to a set angle or more and the signal from the limit switch is controlled. When input to the device, an operation signal is transmitted from the control device to a control valve for the hydraulic cylinder, and the hydraulic cylinder switches the front wheel transmission to the front wheel speed-up state. A limit switch is provided at the fourth speed position and at the high speed position of the auxiliary transmission lever, and the main transmission lever is moved to the fourth speed position,
When driving at high speed with the sub shift lever at the high speed position,
In some cases, an operation signal is not issued to the control valve despite the steering operation exceeding the set angle of the front wheels.
That is, when the traveling transmission is switched to the low-speed side, when the front wheel as the steerable wheel is steered to a predetermined turning angle or more, the front wheel as the front wheel speed increasing device is controlled by the control device as the turning control means. When the transmission is automatically switched to the entry side and the traveling transmission is switched to the high-speed side, the front wheel speed increasing device is engaged even if the steering wheel is steered beyond the set turning angle. Was not switched to the side. That is, the small-turn turning control is executed when the vehicle runs at a low speed, and the small-turn turning control is suppressed when the vehicle runs at a high speed.

[0003]

Conventionally, depending on whether a detection switch is provided at each of a plurality of operating positions of the shift lever or a detection switch is provided at each of the main shift lever and the auxiliary shift lever, either low-speed or high-speed running is performed. However, there is a problem that the structure becomes complicated from the viewpoint of the sensor mechanism, because it is possible to detect whether the vehicle is in the vehicle or not, and to make a small turn, or to check. SUMMARY OF THE INVENTION An object of the present invention is to provide a traveling control device for a work vehicle in which a small turning operation can be easily performed and a small turning operation while traveling at a high speed is restrained. To get it.

[0004]

The constitution, operation and effect of the invention according to claim 1 are as follows.

[Structure] A cutting state in which the driving speed of a traveling steerable wheel located at one of the front and rear ends of the body is the same as or substantially the same as that of a non-steerable traveling wheel located at the other end. With a front wheel speed-up device that can be switched to an on state where the drive speed of the steered wheels is higher than that of the non-steered wheels, and when the steered wheels are steered beyond the set turning angle,
A traveling control device for a work vehicle including a turning control means for automatically switching a front wheel speed increasing device to an entrance side to make a small turn of the aircraft, comprising a speed sensor for detecting a traveling speed of the aircraft. If the speed detected by the speed sensor is less than the set speed, the turning control means enables the switching operation to the entrance side of the front wheel speed increasing device, and if the speed detected by the speed sensor is equal to or more than the set speed, the turning control means A check means for disabling the switching operation of the front wheel speed increasing device to the entrance side, and a state of the check means at the time of the steering operation is detected when the steerable wheel is steered beyond a set turning angle. From the time when the steered wheel is steered beyond the set turning angle to the time when the steering wheel is returned to the steering state with less than the set turning angle, the front wheel acceleration is given priority over the information from the speed sensor. It is provided with a maintenance control means for maintaining a location to remain at the wheel steering operation.

[Operation] When the steered wheels are driven at a higher speed than the non-steered wheels to make a small turn, the minimum speed among the running speeds at which a trouble such as the body swaying is likely to occur is set as the set speed. I do. A speed sensor, such as a rotating shaft that transmits the rotational output of the traveling transmission to the front and rear wheels, detects a body traveling speed based on the number of rotations of a rotating member linked to the wheels, and adopts a speed sensor for the traveling transmission. Compared to the related art, which detects based on the speed state, the number of sensors required is smaller than that of the related art. The sensor detects whether the vehicle is traveling at a low speed or a high speed, and operates while keeping the traveling speed below the set speed. When the directional wheel is steered beyond the set turning angle, the front wheel speed increasing device is automatically turned on because the restraint means enables the turning control device to switch the front wheel speed increasing device to the entry side. Side, the steered wheels are driven at a higher speed than the non-steered wheels, and the aircraft turns with a small turning radius. However, even if the steering wheel is steered beyond the set turning angle, if the vehicle traveling speed is equal to or higher than the set speed, the turning control means cannot switch the front wheel speed increasing device to the entrance side by the turning control means. The steering wheel and the non-steering wheel are driven at the same or almost the same speed, and the aircraft turns with a standard turning radius. Things.

After the steering wheel is steered beyond the set turning angle, the speed detected by the speed sensor is increased from below the set speed until the steering wheel is returned to the steering state smaller than the set turning angle. Even if it changes or changes from the above to less than the above, the front wheel speed increasing device keeps the steering wheel in the on or off state that was at the time of steering operation at the set turning angle by the maintenance control means. Will be maintained. That is, when the steering wheel is steered to a value equal to or greater than the set turning angle while keeping the traveling speed lower than the set speed, and the front wheel speed increasing device is switched to the inbound side, and the aircraft makes a small turn, the steering is performed. Even if the traveling speed rises above the set speed in the middle of the turning operation of the directional wheels to the steering state of less than the set turning angle, the front wheel speed increasing device is switched to the cutting side and the turning radius is reduced. The vehicle can turn while maintaining the front wheel speed increasing device in the on state so as not to change from the small radius to the standard radius. Then, when the steering wheel is steered to the set turning angle or more while the traveling speed is set to the set speed or more, and the front wheel speed increasing device is operated to the turning side, and the aircraft turns with the standard turning radius, The front wheel speed increasing device is switched to the entry side even if the traveling speed may drop below the set speed in the middle of the steering wheel being returned to the steering state with less than the set turning angle, and The turning can be performed while maintaining the front wheel speed increasing device in the off state so that the turning radius does not change from the standard radius to the small radius.

[Effect] When the vehicle is traveling at a low speed less than the set speed, the steering wheel can be easily turned only by performing the steering operation of the steering wheel, and the working device can be quickly positioned in the next work line. When traveling at a speed higher than the set speed, the small-turn turning is restrained by the restraining means, and the body steering is advantageously controlled so that disturbance in the field or shaking of the body is unlikely to occur. it can. In addition, the structure can be simplified so that it is possible to detect whether the vehicle is traveling at a low speed or a high speed with a smaller number of sensors than in the past, which is advantageous in terms of economy and the like. In addition, in the middle of turning, even if the running speed changes due to an accelerator operation or the like, the turning-on or turning-off state of the front wheel speed increasing device when the front wheel speed increasing device starts turning for the maintenance operation by the maintenance control means. And the front wheel speed changer changes from on to off or off to on, making it difficult to drive in the direction different from the intended direction of the aircraft, or the ride quality is poor Such a situation is unlikely to occur and the vehicle can be operated advantageously.

The structure, operation and effect of the invention according to claim 2 are as follows.

[Structure] A cutting state in which the driving speed of a traveling steerable wheel located at one of the front and rear ends of the body is the same or substantially the same as that of a non-steerable traveling wheel located at the other end. A front wheel speed-up device that can be switched to an on state in which the driving speed of the steered wheels is higher than that of the non-steered wheels, and a pair of body steerings that respectively act on the pair of left and right non-steered wheels When the steered wheels are steered beyond the set turning angle, the front wheel speed increasing device and the airframe steering brake acting on the non-steered wheels inside the turn are automatically set on the entry side. In a traveling control device for a work vehicle having a turning control means for turning the aircraft in a small turn by switching operation, a speed sensor for detecting an actual aircraft traveling speed is provided, and the speed detected by the speed sensor is less than a set speed. If any, turn system Enabling the switching operation to the front wheel acceleration device and machine gymnastics countercurrent brake inlet side by means, if the detection rate by the speed sensor is set speed or more,
Check means for disabling the switching operation of the front wheel speed increasing device and the fuselage steering brake to the entrance side by the turning control means,
When the steerable wheel is steered to the set turning angle, the state of the check means at the time of this steering operation is detected, and after the steerable wheel is steered to the set turn angle or more, the set turning angle is obtained. And a maintenance control means for maintaining the front wheel speed increasing device and the body steering brake in a state at the time of the wheel steering operation prior to the operation of returning to the steering state of less than the speed sensor. It is.

[Operation] When the steered wheels are driven at a higher speed than the non-steered wheels, and the steering brake is applied to the non-steered wheels on the inner side of the turn, the vehicle body shakes when turning slightly. The minimum speed among the running speeds that are easy to perform is set as the set speed. A speed sensor is used to detect the running speed of the vehicle based on the rotational speed of a rotating member such as a rotating shaft that transmits the rotational output of the traveling transmission to the front and rear wheels. Compared with the related art, which detects based on the state, the number of sensors required is smaller, and it is detected whether the vehicle is traveling at a low speed or a high speed, and the steering is performed while keeping the traveling speed below the set speed. When the die wheel is steered beyond the set turning angle, the front wheel speed increasing device and the front wheel speed increasing device are used in order to enable the restraint means to switch the front wheel speed increasing device and the airframe steering brake to the entrance side by the turning control device. The aircraft steering brake is automatically switched to the entry side, the steered wheels are driven at a higher speed than the non-steered wheels, and the brakes are applied to the non-steered wheels inside the turn to make the aircraft smaller. Turning half In going to turn. However, even if the steering wheel is steered beyond the set turning angle, if the vehicle traveling speed is equal to or higher than the set speed, the restraining means is controlled by the turning control means to the front wheel speed increasing device and the entrance side of the body steering brake. In order to make it impossible to switch to, the front wheel speed increasing device and the airframe steering brake are operated with the steering wheel turned off, the steered wheels and the non-steered wheels are driven at the same or almost the same speed, and the The brakes are not applied to the steered wheels, and the aircraft turns with a standard turning radius.

After the steerable wheel is steered beyond the set turning angle, the speed detected by the speed sensor is changed from below the set speed to the steering speed smaller than the set turning angle until the steering wheel is operated again. The front wheel speed-increasing device and the aircraft steering brake are in the on or off state when the steering wheel was steered to the set turning angle, even if it changed or changed from the above to less than Is maintained by the maintenance control means. That is, the steering wheel is steered to a value equal to or greater than the set turning angle while keeping the traveling speed less than the set speed, and the front wheel speed increasing device and the body steering brake are switched to the inbound side to make a small turn. In this case, even if the traveling speed may increase to the set speed or more before the steering wheel is returned to the steering state of less than the set turning angle, the front wheel speed increasing device and the body steering brake Can be turned while maintaining the front wheel speed increasing device and the body steering brake in the on state so that the turning radius does not change from the small radius to the standard radius due to being switched to the turning side. Then, the steering wheel is steered beyond the set turning angle while keeping the running speed higher than the set speed, the front wheel speed increasing device and the body steering brake are operated to the cut side, and the body turns with the standard turning radius. When the steering wheel is returned to the steering state with less than the set turning angle, the front wheel speed increasing device and In order to prevent the body steering brake from being switched to the entry side and the turning radius from changing from the standard radius to the small radius, the vehicle can turn while maintaining the front wheel speed increasing device and the body steering brake in the off state.

[Effect] When the vehicle is traveling at a low speed lower than the set speed, the steering wheel can be easily turned only by performing the steering operation of the steering wheel, and the working device can be quickly positioned in the next work line. When traveling at a speed higher than the set speed, the small-turn turning is restrained by the restraining means, and the body steering is advantageously controlled so that disturbance in the field or shaking of the body is unlikely to occur. it can. In addition, the structure can be simplified so that it is possible to detect whether the vehicle is traveling at a low speed or a high speed with a smaller number of sensors than in the past, which is advantageous in terms of economy and the like. In addition, in the course of turning, even when the running speed changes due to an accelerator operation or the like, the front wheel speed increasing device and the body steering brake enter a turn for the maintenance operation by the maintenance control means. The vehicle remains in the on or off position, and the front wheel speed increasing device and the aircraft steering brake change from on to off or from off to on, and the vehicle travels in a direction different from the direction intended by the aircraft. It is difficult to cause such a situation that the ride becomes difficult or the ride comfort deteriorates, and the vehicle can be driven advantageously.

The structure, operation and effect of the invention according to claim 3 are as follows.

[Structure] A cut-off state in which the driving speed of a traveling steerable wheel located at one of the front and rear ends of the body is the same or substantially the same as that of a non-steerable traveling wheel located at the other end. A front wheel speed-up device that can be switched to an on state in which the driving speed of the steered wheels is higher than that of the non-steered wheels, and a pair of body steerings that respectively act on the pair of left and right non-steered wheels When the steered wheels are steered beyond the set turning angle, the front wheel speed increasing device and the airframe steering brake acting on the non-steered wheels inside the turn are automatically set on the entry side. A first turning control mode in which the body is turned in a small turn by switching operation to the first wheel, and when the steerable wheels are steered beyond a set turning angle, the front wheel speed increasing device and the front wheel speed increasing brake of the body steering brake are operated. Automatically switch only the device to the entry side and turn the aircraft In a traveling control device for a work vehicle provided with turning control means operable to switch between a second turning control mode and a second turning control mode, a speed sensor for detecting an actual body running speed; Second
In any of the turning control modes of the turning control mode, if the speed detected by the speed sensor is lower than the set speed, based on information from the speed sensor, the turning control means controls the front wheel speed increasing device and the body steering brake. Checking means for enabling a switching operation to the entrance side, and disabling the switching operation of the front wheel speed increasing device and the body steering brake to the entrance side by the turning control means if the speed detected by the speed sensor is equal to or higher than a set speed. When the steering wheel is steered to the set turning angle, the state of the check means at the time of this steering operation is detected, and the setting is performed after the steering wheel is steered to the set turning angle or more. Until the steering state is returned to the steering angle less than the turning angle, the front wheel speed increasing device and the aircraft steering brake are maintained in the state at the time of the wheel steering operation prior to the information from the speed sensor It is a maintenance control means that.

[Operation] The minimum speed among the running speeds in which a trouble such as the body swaying during a small turn is likely to occur is set as the set speed. A speed sensor is used to detect the running speed of the vehicle based on the rotational speed of a rotating member such as a rotating shaft that transmits the rotational output of the traveling transmission to the front and rear wheels. The number of sensors required is smaller than in the related art, which detects based on the state, and detects whether the vehicle is traveling at a low speed or a high speed. When the turning control means is switched to the first turning control mode, when the steering wheel is steered to be equal to or more than the set turning angle while keeping the traveling speed less than the set speed, the check means is turned on. In order to enable the turning control means to switch the front wheel speed increasing device and the body steering brake to the entrance side, the front wheel speed increasing device and the body steering brake are automatically switched to the entrance side, and the steered wheels are operated. The non-steered wheels are driven at a higher speed than the unsteered wheels, and the brakes are applied to the non-steered wheels inside the turning, so that the aircraft turns with a small turning radius. However, even if the steering wheel is steered beyond the set turning angle, if the vehicle traveling speed is equal to or higher than the set speed, the restraining means is controlled by the turning control means to the front wheel speed increasing device and the entrance side of the body steering brake. In order to make it impossible to switch to the steering wheel, the front wheel speed increasing device and the body steering brake are operated in the off state, and the steered wheels and the non-steered wheels are driven at the same or almost the same speed. The brakes are not applied to the non-steering wheels, and the aircraft turns with a standard turning radius.
When the turning control means is switched to the second turning control mode, when the steering wheel is steered to be equal to or more than the set turning angle while keeping the traveling speed less than the set speed, the drag control means is turned on. In order to enable the turning control means to switch the front wheel speed increasing device to the entry side, the front wheel speed increasing device is automatically switched to the entry side and the steered wheels are driven at a higher speed than the non-steered wheels. Then, the aircraft turns with a small turning radius. However, even if the steering wheel is steered beyond the set turning angle, if the vehicle traveling speed is equal to or higher than the set speed, the turning control means cannot switch the front wheel speed increasing device to the entrance side by the turning control means. The steering wheel and the non-steering wheel are driven at the same or almost the same speed, and the aircraft turns with a standard turning radius. Things.

The turning control means includes a first turning control mode and a second turning control mode.
In any of the turning control modes, after the steering wheel is steered beyond the set turning angle, the speed sensor is used until the steering wheel is returned to the steering state with less than the set turning angle. Even if the detected speed changes from less than the set speed to more than or less than the set speed, the front wheel speed increasing device and the aircraft steering brake steer the steerable wheels to the set turning angle. It is maintained by the maintenance control means in the on or off state at the time of operation. That is, the steering wheel is steered to a value equal to or greater than the set turning angle while the traveling speed is lower than the set speed, and the front wheel speed increasing device and the body steering brake are switched to the entry side to make a small turn. In some cases, even if the traveling speed rises above the set speed before the steering wheel is returned to the steering state with less than the set turning angle, the front wheel speed increasing device and the aircraft steering brake Can be turned while maintaining the front wheel speed increasing device and the aircraft steering brake in the on state so that the turning radius does not change from the small radius to the standard radius due to being switched to the turning side. Then, the steering wheel is steered beyond the set turning angle while keeping the running speed higher than the set speed, the front wheel speed increasing device and the body steering brake are operated to the cut side, and the body turns with a standard turning radius. When driving, even if the traveling speed may drop below the set speed before the steering wheel is returned to the steering state with less than the set turning angle, the front wheel speed increasing device or In order to prevent the body steering brake from being switched to the entry side and the turning radius from changing from the standard radius to the small radius, the vehicle can turn while maintaining the front wheel speed increasing device and the body steering brake in the off state.

[Effect] Regardless of whether the turning control means is switched between the first turning control mode and the second turning control mode, if the vehicle is running at a low speed less than the set speed, the steering type wheel is controlled. By simply performing the steering operation, it is possible to easily make a small turn and the work equipment can be quickly aligned with the next work line, and when traveling at a speed higher than the set speed, a small turn The body can be steered advantageously so that the turning is restrained and the disturbance of the field and the shaking of the body hardly occur. In addition, the structure can be simplified so that it is possible to detect whether the vehicle is traveling at a low speed or a high speed with a smaller number of sensors than in the past, which is advantageous in terms of economy and the like. In addition, in the course of turning, even if the running speed changes due to accelerator operation or the like, the front wheel speed increasing device or the body steering brake was turned for maintenance operation by the maintenance control means. The vehicle will remain in the on or off state, and the front wheel speed-up device or aircraft steering brake will change from on to off, or from off to on, and drive in a direction different from the intended direction of the aircraft. It is difficult to cause such a situation that the ride becomes difficult or the ride comfort deteriorates, so that the vehicle can be driven advantageously.

The structure, operation and effect of the invention according to claim 4 are as follows.

[Structure] In the structure of the present invention according to claim 3, when the turning control means is in the first turning control mode, the minimum speed detected by the speed sensor for executing the towing production by the restraining means. The value is set to be smaller than the minimum value of the speed detected by the speed sensor for executing the towing by the restraining means when the turning control means is in the second turning control mode.

[Operation] In the case of turning in a small turn, the higher the traveling speed of the body, the more likely the disturbance in the field during turning is in the first turning control mode than in the second turning control mode. The swinging motion of the aircraft is likely to occur. Accordingly, the first field control mode and the second page control mode can be used to make the field disturbance less likely to cause the body sway even when making a small turn in the second turn control mode.
The traveling speed at which the vehicle can make a small turn when switched to the turning control mode is set to be lower than the traveling speed at which the vehicle can make a small turn when switched to the second turning control mode.

[Effect] Even when the vehicle turns while switching to either the first turning control mode or the second turning control mode,
The turbulence in the field and the swaying motion of the airframe hardly occur as much as possible, so that the vehicle can turn advantageously.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a pair of left and right front wheels 1, 1 which are steerable and drivable and a pair of left and right rear wheels 2, 2 which are not steerable and drivable. A steering wheel 3 for steering the front wheel 1;
An agricultural tractor having a lift arm 5 for connecting various working devices such as a rotary tilling device so as to be able to move up and down freely and a power take-off shaft 6 for transmitting power to the connected working devices, at the rear of a traveling body having a driver's seat 4 and the like. Is configured.

An engine E is provided at a driving portion located at a front portion of the traveling body, and a rear wheel differential mechanism 11 is provided at a rear portion inside a case of a transmission case 8 forming a rear portion of the traveling body.
A front wheel differential mechanism 13 is provided in a left and right intermediate portion of a front wheel transmission case 38 that supports the front wheel 1 at both ends so as to be swingably steerable. The transmission mechanism shown in FIG. Power is transmitted to the front wheel differential mechanism 13. That is, the rotational power taken out of the engine E via the main clutch 7 is input to the transmission case 8 and transmitted to the traveling transmission 9, and the rotational power of the output shaft 10 of the traveling transmission 9 is used for the rear wheels. The transmission is branched and transmitted to the differential mechanism 11 and the front wheel speed increasing device 20.
The rotation power of the output shaft 21 of zero is transmitted to the front wheel differential mechanism 13 via the rotation shaft 12. The traveling transmission 9 includes a main transmission (not shown) that shifts the rotational power from the engine E to a plurality of stages by changing the shift gear, and forwards the rotational power from the main transmission by changing the shift gear. A forward / reverse switching device (not shown) for switching between a driving force and a reverse driving force, switching the forward driving force or the reverse driving force from the forward / reverse switching device between a high speed side and a low speed side by changing a shift gear and outputting the output. Axis 10
A sub-transmission (not shown) for transmitting the power to the vehicle is provided.

As shown in FIG. 3, an input gear 22 of the front wheel speed increasing device 20 and an output gear of which the output shaft 10 of the traveling transmission 9 is integrally rotatable are provided at the inner bottom of the transmission case 8. 14, the input gear 22 is integrally rotatably provided at the other end of an input shaft 23 to which the input gear 22 is rotatably connected at one end. The speed-up transmission gear 25 meshes with one end of the output shaft 21 and the standard transmission gear 26 that meshes with the input gear 22 is supported at the other end of the output shaft 21 so as to be rotatable relative to each other. A friction clutch mechanism 27 is provided between the output shaft 21 and the standard transmission gear 26 and the output shaft 21.
Is provided with a meshing clutch mechanism 29 between a switching body 28 which is integrally rotatable and slidably provided by spline engagement to constitute the front wheel speed increasing device 20. The friction clutch mechanism 27 includes a clutch body 27a provided with the speed increasing transmission gear 25 so as to be rotatable integrally, a passive body 27b provided with the output shaft 21 so as to be able to rotate integrally by spline engagement,
A piston 31a is provided at the other end of the shifter 30 having one end engaged with the switching body 28 for relative rotation only, the multi-plate friction clutch mechanism body 27c being located between the passive body 27b and the clutch body 27a. With the hydraulic cylinder 31 connected, it can be turned on and off,
By this on / off operation, the speed increasing transmission gear 25 is connected to the output shaft 2.
1 is connected so as to rotate integrally, and this connection is released. The meshing clutch mechanism 29 is composed of an internal gear provided with a standard transmission gear 26 rotatably integrally on one side and a gear provided with a switching body 28 rotatable integrally on one side. An on / off operation can be performed by the on / off operation 31, and the standard transmission gear 26 is connected to the output shaft 21 so as to rotate integrally with the output shaft 21 by this on / off operation, and this connection is released. That is, when the hydraulic cylinder 31 is operated to the extension side, and the hydraulic cylinder 31 slides the switching body 28 through the shifter 30 toward the clutch body 27a and presses against the multi-plate friction clutch mechanism main body 27b, the multi-plate type Since the friction plates of the friction clutch mechanism main body 27b are in pressure contact with each other, the friction clutch mechanism 27 is turned on,
The speed-up transmission gear 25 and the output shaft 21 are connected by friction so that the two 25 and 21 rotate integrally. At this time, since the gear of the switching body 28 is disengaged from the internal gear of the standard transmission gear 26, the meshing clutch mechanism 29 is disengaged, so that the standard transmission gear 26 and the output shaft 21 rotate relative to each other. The connection between 26 and 21 is released. In contrast,
By operating the hydraulic cylinder 31 to the shortening side, the hydraulic cylinder 31
Switches the switching body 28 via the shifter 30 to the standard transmission gear 2.
When the gear of the switching body 28 is meshed with the internal gear of the standard transmission gear 26 by sliding to the direction 6, the meshing clutch mechanism 29 is engaged due to the gear meshing, and the standard transmission gear 26 is engaged. The two 26 and 21 are connected via a switching body 28 so that the output shaft 21 and the output shaft 21 rotate integrally.
At this time, since the pressure contact between the friction plates of the multi-plate friction clutch mechanism main body 27c is released, the friction clutch mechanism 27
Is disconnected, and the connection between the speed increasing transmission gear 25 and the output shaft 21 is released so that the output shaft 21 and the output shaft 21 rotate relative to each other.

Thus, when the hydraulic cylinder 31 is operated to expand and contract to operate the friction clutch mechanism 27 and the meshing clutch mechanism 29 of the meshing clutch mechanism 29, the front wheel speed increasing device 20 is turned off. The rotational power input from the output shaft 10 of the traveling transmission 9 to the input gear 22 is transmitted to the output shaft 21 via the standard transmission gear 26, the meshing clutch mechanism 29, and the switching body 28, and the rotational power of the output shaft 21 is transmitted. Is output to the rotating shaft 12 as the front wheel driving force, and the driving speed of the front wheel 1 is made equal to or almost the same as the driving speed of the rear wheel 2 because of the transmission ratio between the input gear 22 and the standard transmission gear 26. That is, forward driving force or reverse driving force is transmitted to the left and right front wheels 1 and 1 such that the average peripheral speed of the left and right front wheels 1 and 1 is equal to or approximately equal to the average peripheral speed of the left and right rear wheels 2 and 2. On the other hand, when the friction clutch mechanism 27 of the friction clutch mechanism 27 and the meshing clutch mechanism 29 is turned on, the front wheel speed increasing device 20 is turned on, and the output shaft 10 of the traveling transmission 9 is turned on. Input gear 22
To the output shaft 21 via the input shaft 23, the transmission gear 24, the speed increasing transmission gear 25, and the friction clutch mechanism 27.
And the rotational power of the output shaft 21 is output to the rotary shaft 12 as front wheel driving force, and the driving speed of the front wheels 1 is changed to the driving speed of the rear wheels 2 due to the transmission ratio of the transmission gear 22 and the speed increasing transmission gear 25. Be faster than speed. That is, the left and right front wheels 1,
1. The average peripheral speed of the left and right rear wheels 2, 2 is about 1.
A forward driving force or a reverse driving force is transmitted to the left and right front wheels 1 and 1 so as to be nine times as large.

As shown in FIG. 2, the rear wheel differential mechanism 1
A body steering brake 32 is provided on each of a pair of left and right output shafts.
a, 32b, and each of the body steering brakes 32a, 32b is provided with a hydraulic brake cylinder 33a,
33b, the on / off operation is performed, and when the on / off operation is performed, a friction braking force is applied to the output shaft of the rear wheel differential mechanism 11, whereby the output shaft is transmitted to the left or right rear. To apply a friction braking force to the wheel 2,
Thereafter, the steering operation is performed so that the wheels 2 are turned inside and the aircraft is turned.

As shown in FIG. 4, a change-over switch is linked to a turning angle sensor 34 for detecting the steering direction and turning angle of the left and right front wheels 1, 1 and a speed sensor 35 for detecting the actual running speed of the body. The front wheel speed increasing device 20 is provided with a turning control mechanism 37 provided with a front wheel speed increasing device 20 by operating a hydraulic cylinder 31 by outputting an operation signal to an electromagnetic valve mechanism (not shown) of the hydraulic cylinder 31. In order to perform the switching operation, the brake cylinders 33a and 33b are operated by outputting an operation signal to an electromagnetic valve (not shown) of each of the pair of brake cylinders 33a and 33b. The pair of fuselage steering brakes 32a,
32b is linked to perform these switching operations.

The turning angle sensor 34 rotatably and steerably supports the front wheel 1 at both ends, and is supported at an intermediate portion of a front wheel transmission case 38 in which the front wheel differential mechanism 13 is mounted. It consists of a detection switch.
(1) A set turning angle set as a target for detection of a switch operation member 42 provided in a pitman arm 41 that swings each knuckle arm 39 via a rod 40, and for causing the front wheel 1 to execute small turning control. A
In addition to detecting whether or not the steering has been performed, it detects whether the steering direction when the steering operation is performed beyond the set turning angle A is rightward or leftward, and turns each detection result as an electric signal. Output to the control mechanism 37. That is, when the steering handle 3 is rotated to operate the pitman arm 41 to steer the left and right front wheels 1, 1,
In both the case where the steering wheel 1 is steered from the straight running direction to the left and the case where the steering wheel is steered rightward, if the steering angle of the front wheel 1 located inside the turning from the straight running direction is less than 35 degrees, the switch operation is performed. The member 42 does not come into contact with the operation arm 34a of the detection switch, and the operation arm 34a is not pressed to the left or right. Then, the cutting angle sensor 34
Detects that the turning angle of the front wheel 1 has not reached the set turning angle A. When the left and right front wheels 1 and 1 are steered to the left, the switch operation member 42 comes into contact with the operation arm 34a as the steering angle of the left front wheel 1 positioned inside the turning from the straight traveling direction becomes 35 degrees. The switch arm 42a continues to press the operation arm 34a to the left while the operation arm 34a starts to be pressed to the left and the steering angle of the left front wheel 1 is between 35 degrees and the steering limit. Then, the turning angle sensor 34 detects that the front wheel 1 is being steered to the left by more than the set turning angle A. When the right and left front wheels 1 and 1 are steered rightward, the switch operation member 42 comes into contact with the operation arm 34a as the steering angle of the right front wheel 1 located inside the turning from the straight traveling direction becomes 35 degrees. The switch arm 42a continues to press the operation arm 34a rightward while the operation arm 34a starts to be pressed rightward and the steering angle of the right front wheel 1 is between 35 degrees and the steering limit. Then, the turning angle sensor 34 detects that the front wheel 1 is steered rightward beyond the set turning angle A or more.

As shown in FIG. 4, the speed sensor 35
Comprises a gear pulse sensor, detects the traveling speed of the aircraft body with the output gear 14 provided so that the output shaft 10 is rotatable integrally, and outputs the detection result to the turning control mechanism 37. That is, each time the tooth portion of the output gear 14 passes through the detection range of the speed sensor, a pulse is transmitted to the turning control mechanism 37, and the rotation speed of the output shaft 10 is detected based on the number of pulse transmissions within the set time. The actual traveling speed of the aircraft is detected based on the detected rotation speed.

As shown in FIG. 4, the changeover switch 3
Reference numeral 6 denotes a push-button switch provided on an operation panel 43 located in a driving unit of the traveling body.
The command to output one command to the turning control mechanism 37 from the three types of commands of the cutting mode, the first turning control mode, and the second turning control mode, and each time the push operation is performed, outputs the command. It is configured to sequentially switch between the three types of commands. As shown in FIG. 4, a display lamp 36a located near the changeover switch 36 is provided on the operation panel 34. The display lamp 36a is provided by the changeover switch 3
Numeral 6 is lit and displayed when a command for the first turning control mode is output.

The turning control mechanism 37 is constituted by a microcomputer, and when the changeover switch 36 outputs a command for a cut-off mode, the control operation is not performed and the front wheel speed increasing device 20 and the body steering brake 32a are turned off. , 32a
When the changeover switch 36 outputs the command of the first turning control mode or the second turning control mode without performing the operation of the turning angle sensor 3 and the turning angle sensor 3
4, the speed sensor 35, the changeover switch 36, and the front wheel speed increasing device 20 and the pair of body steering brakes 32 a, 32 a based on the control flow shown in FIGS. 5 and 6.
And are automatically operated.

That is, when the changeover switch 36 outputs a command for the first turning control mode or the second turning control mode, the flag is set to 0 (step # 1), and the front wheel speed increasing device 20 is turned off (step # 1). In step # 2), the body steering brake 32a of the left rear wheel 1 and the body steering brake 32b of the right rear wheel 1 are turned off (step # 3, step # 4). It is determined whether S is equal to or greater than the set turning angle A (step # 5). When it is determined that the detected turning angle S is not equal to or larger than the set turning angle A, the process returns to step # 2. When it is determined that the detected turning angle S is equal to or larger than the set turning angle A, the process proceeds to step # 6. It is determined whether or not the command from the changeover switch 36 is the first turning control mode. If it is determined that the command from the changeover switch 36 is in the first turning control mode, the process proceeds to step # 7, and it is determined whether the speed V detected by the speed sensor 35 is lower than the first set speed N1. When the detected speed V is equal to the first set speed N1
If it is determined that the speed is lower, the process proceeds to step # 8, and it is determined whether the flag is 1. If it is determined that the flag is not 1, the front wheel speed increasing device 20 is switched to the entry side (step # 9), and the process proceeds to step # 10, where the steering direction detected by the turning angle sensor 34 is left. Determine whether or not. If it is determined that the vehicle is facing left, the body steering brake 32a of the left rear wheel 1 is turned on (step # 11) and whether the detected angle S detected by the angle sensor 34 is smaller than the set angle A. It is determined whether or not it is (step # 12). If it is determined that the detected turning angle S is not smaller than the set turning angle A, the process returns to step # 9. If it is determined that the detected turning angle S is smaller than the set turning angle A, the process returns to step # 1. Return. In step # 6, the command from the changeover switch 36 is
If it is determined that the mode is not the turning control mode (this corresponds to the case where the command from the changeover switch 36 is the second turning control mode), the process proceeds to step # 13, and the speed V detected by the speed sensor 35 is set to the above-mentioned value. First set speed N1
It is determined whether the speed is lower than the second set speed N2, which is higher than the second set speed N2. If it is determined that the detected speed V is lower than the second set speed N2, the process proceeds to step # 14, and it is determined whether the flag is 1. When it is determined that the flag is not 1, the front wheel speed increasing device 20 is operated to the inbound side (step # 15), and it is determined whether the detected turning angle S detected by the turning angle sensor 34 is smaller than the set turning angle A. A determination is made (step # 16). If it is determined that the detected turning angle S is not smaller than the set turning angle A, the process returns to step # 15. If it is determined that the detected turning angle S is smaller than the set turning angle A, the process returns to step # 1. When it is determined in step # 7 that the speed V detected by the speed sensor 35 is not lower than the first set speed N1, and in step # 13
When it is determined that the detected speed V is not lower than the second set speed N2, the flag is set to 1 (step # 17).
At the same time, it is determined whether or not the turning angle S detected by the turning angle sensor 34 is smaller than the set turning angle A (step # 1).
8). If it is determined that the detected turning angle S is not smaller than the set turning angle A, the process returns to step # 2. If it is determined that the detected turning angle S is smaller than the set turning angle A, step # is performed.
Return to 1. When it is determined in step # 8 that the flag is 1, and when it is determined in step # 14 that the flag is 1, the process proceeds to step # 18. Step # 10
If it is determined that the steering direction detected by the turning angle sensor 34 is not leftward, the body steering brake 32b of the right rear wheel 1 is turned on (step # 19) and the process proceeds to step # 12. Note that, in this embodiment, the first
The set speed N1 is set to about 3.6 km / h, and the second set speed N2 is set to about 5 km / h.

Thus, the turning control mechanism 37 constitutes the turning control means 44, the traction control means 45, and the maintenance control means 46, and the respective means 44, 45, 46 operate as follows. That is, the turning control means 44 is provided with the changeover switch 3
6 switches to a state of turning control off, a state of the first turning control mode, and a state of the second turning control mode. In any of the first turning control mode and the second turning control mode, if the front wheel 1 is in a steering state in a straight ahead direction or in a steering state with a turning angle smaller than the set turning angle A, the turning angle is set. Based on the information from the sensor 34, the front wheel speed increasing device 20 is also provided with a pair of the body steering brakes 32.
a and 32b are also operated in the cut state. In the first turning control mode, when the front wheel 1 is steered to the predetermined turning angle A or more, the front wheel speed increasing device 20 and the front wheel speed increasing device 20 are paired based on the information from the turning angle sensor 34. Of the airframe steering brakes 32a and 32b of the vehicle, the one of the airframe steering brakes 32a or 32 that acts on the rear wheel 2 located inside the turn.
b to the entry side, and the driving speed of the front wheels 1
And the brake is applied to the rear wheel 2 on the inside of the turn to make the aircraft turn slightly. In the state of the second turning control mode, when the front wheel 1 is steered beyond the set turning angle A, the turning angle sensor 34 is turned on.
, Only the front wheel speed increasing device 20 and the front wheel speed increasing device 20 of the body steering brakes 32a and 32b are switched to the entrance side, and the driving speed of the front wheel 1 is changed to the rear wheel 2 speed.
And make the aircraft turn slightly.

When the turning control means 44 is in the first turning control mode, if the traveling speed of the vehicle is lower than the first set speed N1, the turning control means 44 sets the second turning control mode to the second turning control mode.
When the vehicle is in the turning control mode, the second traveling speed N2 is higher than the first traveling speed N1.
If the speed is lower than the speed, the restraining means 45 cancels the towing production for the turning control means 44 based on the information from the speed sensor 35, and the turning control means 44 increases the front wheel speed based on the information from the turning angle sensor 34, respectively. The device 20 and the body steering brakes 32a and 32b can be switched to the entrance side. However, when the turning control means 44 is in the first turning control mode, if the vehicle traveling speed is equal to or higher than the first set speed N1, the turning control means 44 is not used.
Is in the state of the second turning control mode, if the vehicle traveling speed is equal to or higher than the second set speed N2,
The restraint means 45 executes the towing operation for the turning control means 44 based on the information from the speed sensor 35, and the turning control means 44 executes the front wheel speed increasing device 20 and the body steering brake 32 a based on the information from the turning angle sensor 34. , 32b to the entry side.

When the turning angle of the front wheel 1 becomes the set turning angle A as the steering operation is performed, if the restraining means 45 is in the restraining state, the maintenance control means 46 is operated by the information from the restraining means 45. Detecting that the traction means 45 is in the traction state and storing the detection result, from the time when the front wheel 1 is steered to the set turning angle A to the time when the front wheel 1 is returned to the steering state smaller than the set turning angle next time. During this period, regardless of the change in the speed detected by the speed sensor 35, the check means 45 is maintained in the check state regardless of the change. If the braking means 45 is in the braking release state at the time when the steering angle of the front wheel 1 is changed to the set braking angle A as the steering operation is performed, the maintenance control means 46 receives information from the braking means 45 according to the information from the braking means 45. The restraint means 45 detects that the restraint is in the released state and stores the detection result. After the front wheel 1 is steered to the set turning angle A, the steering operation is returned to the steering state smaller than the set turning angle. In the meantime, no matter what value the speed detected by the speed sensor 35 changes, the check means 45 is maintained in the check release state regardless of the change. That is, the maintenance control unit 46 determines whether the turning angle of the front wheel 1 has reached the set turning angle A, regardless of whether the turning control unit 44 is in the first turning control mode or the second turning control mode. The state of the restraint means 45 at the time is detected and stored,
Until the front wheel 1 is returned to the steering state smaller than the set turning angle, the braking means 45 is maintained in the state stored first in preference to the information from the speed sensor 35,
The front wheel speed increasing device 2 in preference to the information from the speed sensor 35
0 and the body steering brakes 32a and 32b are maintained in the off or on state at the time when the front wheel 1 was steered to the set turning angle A. That is, while the vehicle is traveling with the steering operation of the front wheel 1 at or above the set turning angle A, the vehicle traveling speed is equal to or lower than the first set speed N1 or the second set speed N2, and the first set speed. Even if the speed changes from one of N1 and the speed higher than the second set speed N2 to the other, the check means 45 is switched from the check state to the check release state due to the change in the speed, and the front wheel speed increasing device 20 and the body steering are changed. Brake 32a, 32b
Is switched from off to on or the check means 4
5 prevents the front wheel speed-increasing device 20 and the body steering brakes 32a and 32b from being switched from the on state to the off state.

In other words, when the airframe that has reached the end of the work train is turned around to the next work train, if the center distance between the work trains is relatively wide, the turning control means 44 is switched by the changeover switch 36 to the first position. While switching to the two-turn control mode and keeping the traveling speed lower than the second set speed N2,
When the center interval between the work rows is relatively small, the turning control means 44 is switched to the first turning control mode by the changeover switch 36 and the traveling speed is set to the first set speed N.
The steering operation of the front wheels 1 is made to be equal to or more than the set turning angle A while keeping the steering angle to less than 1. Then, in the case of the second turning control mode, the turning control means 44 operates the front wheel speed increasing device 20 to switch from the off state to the on state, and the front wheel 1 is driven at a higher speed than the rear wheel 2. The aircraft can be turned with a small turning radius to quickly align with the next work row. First
In the case of the turning control mode, the turning control means 44 switches the front wheel speed increasing device 20 from the off state to the on state, and turns off the body steering brake 32a or 32b acting on the rear wheel 2 located inside the turning. The front wheel 1 is driven at a higher speed than the rear wheel 2 by switching to the entry, and the brake is applied to the rear wheel 2 inside the turning, so that the aircraft turns with a smaller turning radius and quickly moves to the next work line. Can be aligned.

For example, during operation, the vehicle is driven while the turning control means 44 is kept in the first turning control mode or the second turning control mode, and the front wheel 1 is steered to a predetermined turning angle A or more to steer the fuselage. Even if there is, when the turning control means 44 is in the first turning control mode and the aircraft is running at the first set speed N1 or more, the turning control means 44
In the turning control mode, when the aircraft is running at or above the second set speed N2, the front wheel speed increasing device 20 and the aircraft steering brakes 32a and 32b are turned on for the towing by the restraining means 45. The steering operation can be performed stably so as not to turn around the aircraft without being switched to the side. In the first turning control mode, the traveling speed increases or changes to a first speed N1 or more, for example, by performing an accelerator-up operation during a turning operation at a field edge or the like.
Even if it returns to less than the first set speed N1, in the case of the second turning control mode, even if the running speed rises to or exceeds the second set speed N2 or returns to less than the second set speed N2, Regardless of the speed change, the maintenance control means 46 maintains the traction means 45 in the traction released state, and switches the front wheel speed increasing device 20 and the body steering brakes 32a, 32ba from the on state to the off state, or to the on state. The vehicle can turn stably with no control to return to the normal state.

[Alternative Embodiment] FIG. 7 shows a travel control device having an alternative embodiment. That is, the turning control mechanism 3 which is linked to the turning angle sensor 34 for detecting the steering direction and the turning angle of the left and right front wheels 1 and 1 and the speed sensor 35 for detecting the traveling speed of the body and includes an on / off switch 36.
7 to operate the hydraulic cylinder 31 by outputting an operation signal to an electromagnetic valve mechanism (not shown) of a hydraulic cylinder 31 of the front wheel speed increasing device 20 configured similarly to the front wheel speed increasing device 20 shown in FIG. With this configuration, the front wheel speed increasing device 20 is linked to perform the switching operation. The turning angle sensor 34 has the same configuration as the turning angle sensor 34 shown in FIG. 4, and the speed sensor 35 has the same configuration as the speed sensor 35 shown in FIG.

The turning control mechanism 37 is composed of a microcomputer, and when the on / off switch 36 outputs a control-off command, the control is not turned on and the front wheel speed increasing device 20 is not operated. When the on / off switch 36 outputs a command to enter control, the control enters an on state in which the control operation is performed and the turning angle sensor 34 and the speed sensor 35 are turned on.
The front wheel speed increasing device 20 is automatically operated based on the information from the above and the control flow shown in FIG.

That is, when the ON / OFF switch 36 outputs a command to enter control, the flag is set to 0 (step # 1).
01), the front wheel speed increasing device 20 is turned off (step # 102), and it is determined whether or not the turning angle S detected by the turning angle sensor 34 is equal to or larger than the set turning angle A (step # 103). . If it is determined that the detected turning angle S is not equal to or greater than the set turning angle A, step # 102
When it is determined that the detected turning angle S is equal to or larger than the set turning angle A, the process proceeds to step # 104, and it is determined whether the speed V detected by the speed sensor 35 is lower than the set speed N. When it is determined that the detected speed V is lower than the set speed N, the process proceeds to step # 105, and it is determined whether the flag is 1. If it is determined that the flag is not 1, the front wheel speed increasing device 20 is switched to the entrance side (step # 106) and step # 10 is performed.
7, it is determined whether or not the turning angle S detected by the turning angle sensor 34 is smaller than the set turning angle A (step #).
107). When it is determined that the detected turning angle S is not smaller than the set turning angle A, the process returns to step # 106. When it is determined that the detected turning angle S is smaller than the set turning angle A, the process returns to step # 101. Return. If it is determined in step # 104 that the detected speed V is not lower than the set speed N, the flag is set to 1 (step # 10).
The process proceeds to step # 109 together with 8) to determine whether or not the detected turning angle S detected by the turning angle sensor 34 is smaller than the set turning angle A. When it is determined that the detected turning angle S is smaller than the set turning angle A, the process returns to step # 101. When it is determined that the detected turning angle S is not smaller than the set turning angle A, the process returns to step # 102. Return. Step # 1
If the flag is determined to be 1 at 05,
Move to step # 109. In this embodiment, the set speed N is set to about 5 km / h.

Thus, the turning control mechanism 37 constitutes the turning control means 44, the traction control means 45, and the maintenance control means 46, and the respective means 44, 45, 46 operate as follows. In other words, the turning control means 44 controls the on / off switch 3
The state is switched between a control-off state and a control-on state based on the command output from the control unit 6. If you are in a controlled state,
If the front wheel 1 is in a steering state in which the vehicle is traveling straight ahead, or in a steering state with a turning angle smaller than the set turning angle A, the front wheel speed increasing device 20 is operated to be turned off based on information from the turning angle sensor 34. When the front wheel 1 is steered beyond the set turning angle A, the front wheel speed increasing device 20 is switched to the entrance side based on information from the turning angle sensor 34, and the front wheel 1 is turned.
Is driven at a speed higher than the driving speed of the rear wheels 2 to make a small turn.

If the vehicle traveling speed is lower than the set speed N, the restraining means 45 cancels the towing control for the turning control means 44 based on the information from the speed sensor 35,
The turning control means 44 enables the front wheel speed increasing device 20 to be switched to the entrance side based on the information from the turning angle sensor 34. However, if the vehicle traveling speed is equal to or higher than the set speed N, the restraining means 45 executes the towing production for the turning control means 44 based on the information from the speed sensor 35, and the turning control means 44 The switching operation of the front wheel speed increasing device 20 to the entrance side based on the information is disabled.

When the turning angle of the front wheel 1 becomes the set turning angle A as the steering operation is performed, if the restraining means 45 is in the restraining state, the maintenance control means 46 is controlled by the information from the restraining means 45. Detecting that the traction means 45 is in the traction state and storing the detection result, from the time when the front wheel 1 is steered to the set turning angle A to the time when the front wheel 1 is returned to the steering state smaller than the set turning angle next time. During this period, regardless of the change in the speed detected by the speed sensor 35, the check means 45 is maintained in the check state regardless of the change. If the braking means 45 is in the braking release state at the time when the steering angle of the front wheel 1 is changed to the set braking angle A as the steering operation is performed, the maintenance control means 46 receives information from the braking means 45 according to the information from the braking means 45. The restraint means 45 detects that the restraint is in the released state and stores the detection result. After the front wheel 1 is steered to the set turning angle A, the steering operation is returned to the steering state smaller than the set turning angle. In the meantime, no matter what value the speed detected by the speed sensor 35 changes, the check means 45 is maintained in the check release state regardless of the change. In other words, the maintenance control means 46 detects and stores the state of the restraint means 45 when the turning angle of the front wheel 1 has reached the set turning angle A, and then stores the state of the front wheel 1 below the set turning angle. Until the state is returned to the heading state, the front wheel speed increasing device 20 is given priority over the information from the speed sensor 35 by maintaining the check means 45 in the state stored first in preference to the information from the speed sensor 35. The front wheel 1 is maintained in the on or off state when the steering operation was performed to the set turning angle A. That is, while the front wheel 1 is traveling with the steering operation at or above the set turning angle A, the vehicle running speed changes from one of the speed lower than the set speed N and the set speed N to the other. Also, due to the speed change, the restraint means 45 is switched from the restraint state to the restraint release state, and the front wheel speed increasing device 20 is switched from off to on, or the restraint means 45 is switched from the restraint release state to the restraint state. In other words, the front wheel speed increasing device 20 is prevented from being switched from entering to turning off.

That is, when the aircraft that has reached the end of the work line is turned around to the next work line, the on / off switch 36 is turned on.
The front wheel 1 is steered to a value equal to or greater than the set turning angle A while the turning control means 44 is turned on and the traveling speed is set below the set speed N. Then, the turning control means 44 operates the front wheel speed increasing device 20 to switch from turning to turning on, and the front wheel 1
Is driven at a speed higher than that of the rear wheels 2 so that the aircraft can be turned with a small turning radius and quickly positioned on the next work line.

Even if the vehicle is steered by turning the front wheels 1 to the set turning angle A or more during traveling while the turning control means 44 is in the on state, such as during work, the aircraft is still If the vehicle is traveling at the set speed N or more,
5, the front wheel speed increasing device 20 is not switched to the entrance side, and the steering operation can be performed stably so as not to make a small turn of the aircraft. The travel speed may be increased or changed to a speed higher than or equal to the set speed N by performing an accelerator-up operation in the middle of a turn at a field end or the like.
Even if the speed returns to below, regardless of the speed change, the maintenance control means 46 maintains the traction means 45 in the traction release state up to that time, and switches the front wheel speed increasing device 20 from the entry side to the cut side, or enters the entry side. The vehicle can turn stably with no control to return to the normal state.

[Another Embodiment] FIG. 9 shows a travel control device provided with still another embodiment. That is, the left and right front wheels 1,
A turning angle sensor 34 for detecting a steering direction and a turning angle
And a turning control mechanism 37 including an on / off switch 36 in association with a speed sensor 35 for detecting the traveling speed of the aircraft, and a hydraulic pressure of the front wheel speed increasing device 20 configured similarly to the front wheel speed increasing device 20 shown in FIG. An operation signal is output to an electromagnetic valve mechanism (not shown) of the cylinder 31 to output the hydraulic cylinder 3
1 to operate the front wheel speed-increasing device 20 so as to perform a switching operation thereof, and a pair of body steering brakes 32a, 32b shown in FIG.
A pair of body steering brakes 32 configured similarly to 32b
a and 32b of the respective brake cylinders 33a and 33b
By outputting an operation signal to an electromagnetic valve (not shown) to operate both brake cylinders 33a and 33b, the pair of body steering brakes 32a and 32b can be operated.
b is linked to perform these switching operations. The turning angle sensor 34 has the same configuration as the turning angle sensor 34 shown in FIG. 4, and the speed sensor 35 has the same configuration as the speed sensor 35 shown in FIG.

The turning control mechanism 37 is composed of a microcomputer, and when the on / off switch 36 outputs a control off command, the control operation is not performed and the front wheel speed increasing device 20 and the body steering brake are turned off. When the on / off switch 36 outputs a command to enter control without performing the operation with the switches 32a and 32b, the control is turned on and the information from the turning angle sensor 34 and the speed sensor 35 is output.
Based on the control flow shown in FIG.
And the body steering brakes 32a and 32b are automatically operated.

That is, when the ON / OFF switch 36 outputs a command to enter control, the flag is set to 0 (step # 20).
1) Further, the front wheel speed increasing device 20 is operated to the disengagement side (step # 202), and the airframe steering brake 32a of the left rear wheel 1 and the airframe steering brake 32b of the right rear wheel 1 are also operated to be turned off (step # 202). # 203, step # 204), and it is determined whether or not the turning angle S detected by the turning angle sensor 34 is equal to or larger than the set turning angle A (step # 2).
05). If it is determined that the detected turning angle S is not equal to or greater than the set turning angle A, the process returns to step # 202. If it is determined that the detected turning angle S is equal to or more than the set turning angle A, the process proceeds to step # 206. It is determined whether the speed V detected by the speed sensor 35 is less than the set speed N. If it is determined that the detected speed V is lower than the set speed N, the process proceeds to step # 207, and it is determined whether the flag is 1. If it is determined that the flag is not 1, the front wheel speed increasing device 20 is switched to the on state (step # 20).
At step # 209 together with 8), it is determined whether or not the steering direction detected by the turning angle sensor 34 is leftward. If it is determined that the vehicle is facing leftward, the fuselage steering brake 32a of the left rear wheel 1 is turned on (step # 21).
The process proceeds to step # 211 together with 0), and it is determined whether the turning angle S detected by the turning angle sensor 34 is smaller than the set turning angle A. If it is determined that the detected turning angle S is not smaller than the set turning angle A, the process returns to step # 208, and
If it is determined that the detected turning angle S is smaller than the set turning angle A, the process returns to step # 201. If it is determined in step # 206 that the speed V detected by the speed sensor 35 is not lower than the set speed N, the flag is set to 1 (step # 212), and the process proceeds to step # 213. It is determined whether or not the turning angle S is smaller than the set angle A. If it is determined that the detected turning angle S is not smaller than the set turning angle A, step # 20
Returning to step 2, if it is determined that the detected turning angle S is smaller than the set turning angle A, the process returns to step # 201. If it is determined in step # 207 that the flag is 1, the process proceeds to step # 213. If it is determined in step # 209 that the steering direction detected by the turning angle sensor 34 is not leftward (corresponding to the case where the steering direction of the front wheel 1 is rightward), the body steering brake 3 of the right rear wheel 1 is used.
2b is operated (step # 214), and thereafter, the process proceeds to step # 211. In this embodiment, the set speed N is set to about 3.6 km / h.

Thus, the turning control mechanism 37 constitutes the turning control means 44, the traction control means 45, and the maintenance control means 46, and the respective means 44, 45, 46 operate as follows. That is, the turning control means 44 is provided with the changeover switch 3
The state is switched between a control-off state and a control-on state based on the command output from the control unit 6. If you are in a controlled state,
If the front wheel 1 is in the steering state in which the vehicle is traveling straight ahead or the steering angle is smaller than the set steering angle A, the front wheel speed increasing device 20 also uses the pair of body steering brakes 32a based on the information from the steering angle sensor 34. , 32b are also operated in the cut state. When the front wheel 1 is steered beyond the set turning angle A, the front wheel speed increasing device 20 and the inside of the pair of body steering brakes 32a and 32b are turned on the basis of information from the turning angle sensor 34. , The body steering brake 32a or 32b acting on the rear wheel 2 located on the rear side is switched to the inbound side so that the drive speed of the front wheel 1 is higher than the drive speed of the rear wheel 2 and The brake is applied to the wheels 2 to make the aircraft turn slightly.

If the vehicle traveling speed is lower than the set speed N, the restraining means 45 cancels the towing production for the turning control means 44 based on the information from the speed sensor 35, and the turning control means 44 detects the turning angle from the turning angle sensor 34. The front wheel speed increasing device 20 and the body steering brakes 32a, 32b
Can be switched to the entrance side. However, if the vehicle traveling speed is equal to or higher than the set speed N, the restraining means 45 executes the towing production for the turning control means 44 based on the information from the speed sensor 35, and the turning control means 44 It is impossible to switch the front wheel speed increasing device 20 and the body steering brakes 32a and 32b to the entrance side based on the information.

When the turning angle of the front wheel 1 becomes the set turning angle A as the front wheel 1 is steered, if the restraining means 45 is in a restraining state, the maintenance control means 46 receives information from the restraining means 45 according to the information from the restraining means 45. Detecting that the traction means 45 is in the traction state and storing the detection result, from the time when the front wheel 1 is steered to the set turning angle A to the time when the front wheel 1 is returned to the steering state smaller than the set turning angle next time. During this period, regardless of the change in the speed detected by the speed sensor 35, the check means 45 is maintained in the check state regardless of the change. If the braking means 45 is in the braking release state at the time when the steering angle of the front wheel 1 is changed to the set braking angle A as the steering operation is performed, the maintenance control means 46 receives information from the braking means 45 according to the information from the braking means 45. The restraint means 45 detects that the restraint is in the released state and stores the detection result. After the front wheel 1 is steered to the set turning angle A, the steering operation is returned to the steering state smaller than the set turning angle. In the meantime, no matter what value the speed detected by the speed sensor 35 changes, the check means 45 is maintained in the check release state regardless of the change. In other words, the maintenance control means 46 detects and stores the state of the restraint means 45 when the turning angle of the front wheel 1 has reached the set turning angle A, and then stores the state of the front wheel 1 below the set turning angle. Until the state is returned to the heading state, the check means 45 is maintained in a state stored first in preference to the information from the speed sensor 35, so that the front wheel speed increasing device 20 and the information from the speed sensor 35 take precedence over the information from the speed sensor 35. The vehicle body steering brakes 32a and 32b are maintained in the on or off state which was at the time when the front wheels 1 were steered to the set turning angle A. That is, while the front wheel 1 is traveling with the steering operation at or above the set turning angle A, the vehicle running speed changes from one of the speed lower than the set speed N and the set speed N to the other. Also, due to the speed change, the restraint means 45 is switched from the restraint state to the restraint release state, and the front wheel speed increasing device 20 and the body steering brakes 32a and 32b are switched from the off state to the on state.
Is prevented from being switched from the restraint release state to the restraint state, and the front wheel speed-up device 20 and the body steering brakes 32a and 32b are not switched from the on state to the off state.

That is, when the aircraft that has reached the end of the work line is turned around to the next work line, the on / off switch 36 is turned on.
With the turning control means 44 turned on, the front wheel 1 is turned at the set turning angle A while keeping the traveling speed below the set speed N.
The steering operation is performed as described above. Then, the turning control means 44 switches the front wheel speed increasing device 20 from the off state to the on state, and also switches the body steering brake 32a or 32b acting on the rear wheel 2 positioned inside the turning from the off state to the on state. By driving the front wheel 1 at a higher speed than the rear wheel 2 and applying a brake to the rear wheel 2 on the inside of the turn, the aircraft can be turned with a small turning radius and quickly positioned in the next work line.

Even when the vehicle is driven with the turning control means 44 turned on during work or the like, and the front wheel 1 is steered to a value greater than or equal to the set turning angle A to steer the vehicle, even if the vehicle is steered at the set speed. When the vehicle is running at N or more, the front wheel speed increasing device 20 and the body steering brakes 32a and 32b are not switched to the entrance side for the towing production by the restraining means 45, and the vehicle is stably maintained so as not to make a small turn. Steering operation is possible. For that reason, even if the traveling speed increases or changes to a speed equal to or higher than the set speed N, or returns to less than the set speed N, for example, by performing an accelerator-up operation in the middle of a turning run at a field end or the like,
Regardless of the speed change, the maintenance control means 46 maintains the traction means 45 in the traction-released state, and switches the front wheel speed increasing device 20 and the body steering brakes 32a, 32ba from on to off or back on. The vehicle can turn stably with no control to perform.

The present invention can be applied not only to agricultural tractors but also to rice transplanters and lawnmowers, and these vehicles are collectively referred to as work vehicles.

[Brief description of the drawings]

Fig. 1 Side view of the whole agricultural tractor

FIG. 2 is a drive transmission system diagram for traveling.

FIG. 3 is a sectional view of a front wheel speed increasing device.

FIG. 4 is a block diagram of a control system.

FIG. 5 is a flowchart of turning control.

FIG. 6 is a flowchart of turning control.

FIG. 7 is a block diagram of a control system according to another embodiment.

FIG. 8 is a flowchart of turning control according to another embodiment.

FIG. 9 is a block diagram of a control system according to another embodiment.

FIG. 10 is a flowchart of turning control according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Non-steering wheel 20 Front wheel speed-up device 32a, 32b Aircraft steering brake 35 Speed sensor 44 Turning control means 45 Checking means 46 Maintenance control means N, N1, N2 Set speed V Detection speed A Setting cut Corner

Claims (4)

[Claims] A cutting state in which the driving speed of a traveling steerable wheel located at one of the front and rear ends of the fuselage is the same or substantially the same as that of a non-steerable traveling wheel located at the other end. A front wheel speed-up device that can be switched to an on state in which the driving speed of the directional wheels is higher than that of the non-steered wheels is provided, and when the steered wheels are steered beyond a preset turning angle, the front wheels A traveling control device for a work vehicle including a turning control unit that automatically switches a speed increasing device to an entrance side to make a small turn of the aircraft, and includes a speed sensor that detects an actual aircraft traveling speed, If the speed detected by the speed sensor is lower than the set speed, the turning control means can perform a switching operation to the entrance side of the front wheel speed increasing device. Control hand A check means for disabling the switching operation of the front wheel speed increasing device to the entry side by the control means, and detecting the state of the check means at the time of the steering operation when the steerable wheel is steered to the set turning angle. During the period from when the steerable wheel is steered beyond the set turning angle to when the steering wheel is returned to a steering state smaller than the set turning angle, the front wheel speed increasing device is given priority over the information from the speed sensor. A traveling control device for a working vehicle, comprising a maintenance control means for maintaining a state at the time of a heading operation. 2. A steering state in which the driving speed of a traveling steerable wheel located at one of the front and rear ends of the fuselage is the same or substantially the same as that of a non-steerable traveling wheel located at the other end. A front wheel speed-up device that can be switched to an engaged state in which the driving speed of the directional wheels is higher than that of the non-steered wheels, and a pair of body steering brakes that respectively act on the pair of left and right non-steered wheels When the steered wheels are steered beyond the set turning angle, the front wheel speed increasing device and the body steering brake acting on the non-steered wheels inside the turn are automatically turned to the entry side. What is claimed is: 1. A traveling control device for a working vehicle, comprising: a turning control unit for performing a switching operation to make a small turn of an aircraft, comprising a speed sensor for detecting an aircraft traveling speed, and a speed detected by the speed sensor being lower than a set speed. If the turning control means Enabling the switching operation to the wheel acceleration device and machine gymnastics countercurrent brake inlet side, if the detected speed by the speed sensor is set speed or more,
Check means for disabling the switching operation of the front wheel speed increasing device and the fuselage steering brake to the entrance side by the turning control means,
When the steerable wheel is steered to the set turning angle, the state of the check means at the time of this steering operation is detected, and after the steerable wheel is steered to the set turn angle or more, the set turning angle is obtained. And a maintenance control means for maintaining the front wheel speed increasing device and the body steering brake in a state at the time of the wheel steering operation prior to the operation of returning to the steering state of less than the speed sensor. Traveling control device for a working vehicle. 3. A steering state in which the driving speed of a traveling steerable wheel located at one of the front and rear ends of the fuselage is the same or substantially the same as that of a non-steerable traveling wheel located at the other end. A front wheel speed-up device that can be switched to an engaged state in which the driving speed of the directional wheels is higher than that of the non-steered wheels, and a pair of body steering brakes that respectively act on the pair of left and right non-steered wheels When the steered wheels are steered beyond the set turning angle, the front wheel speed increasing device and the body steering brake acting on the non-steered wheels inside the turn are automatically turned to the entry side. A first turning control mode in which the body is turned in a small turn by switching operation, and a front wheel speed increasing device of the front wheel speed increasing device and the body steering brake when the steerable wheels are steered more than the set turning angle. The second is to automatically switch only the entry side to the entry side and make the aircraft make a small turn What is claimed is: 1. A traveling control device for a work vehicle, comprising: a turning control unit operable to switch between a turning control mode and a turning sensor. In any of the turning control modes of the control mode, if the speed detected by the speed sensor is lower than the set speed, the turning control means can switch the front wheel speed increasing device and the body steering brake to the entrance side. If the speed detected by the speed sensor is equal to or higher than the set speed, the check means for disabling the turning control means to switch the front wheel speed increasing device and the fuselage steering brake to the entry side is disabled, and the steered wheels are cut off. When the steering operation is performed to the corner, the state of the restraint means at the time of the steering operation is detected, and the steering wheel is steered to a setting angle or more, and then the setting is stopped. A maintenance control means for maintaining the front wheel speed increasing device and the body steering brake in the state at the time of the wheel steering operation by prioritizing the information from the speed sensor until the operation is returned to the steering state smaller than the angle; A traveling control device for a working vehicle, comprising: 4. When the turning control means is in the first turning control mode, the turning control means determines the minimum value of the speed detected by the speed sensor for executing the towing production by the checking means. 4. The travel control device for a work vehicle according to claim 3, wherein when the vehicle is in a turning control mode, the traveling speed is set to be smaller than a minimum value of a speed detected by the speed sensor for executing the towing work by the restraining means.