JP2002316660A - Crawler type working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an unexpected move of a vehicle body for steering operation of a steering wheel when a longitudinal inclination or transverse angle of roll of the vehicle body is large and an attitude of the vehicle body is unstable in a crawler type working vehicle structured to turn the vehicle body by adjusting an output rotation to right and left crawler travel gears according to the steering operation amount of the steering wheel. SOLUTION: The longitudinal inclination (pitching angle) of the vehicle body is detected by a pitching sensor and when a change of the pitching angle exceeds a predetermined angle t1 , t2 , the starting of speed change of a reciprocal changeover device is postponed for a predetermined period of time for a steering operation of the steering wheel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crawler type work vehicle, and more particularly to steering control when a vehicle body is tilted.

[0002]

2. Description of the Related Art Conventionally, this type of working vehicle has been disclosed in
As described in Japanese Patent Publication No. 235171, a transmission case is known in which a transmission case is provided at a rear portion of a vehicle body and a crawler-type traveling device is supported on left and right sides of the transmission case. The work vehicle includes a steering handle, a sensor for detecting a rotation operation of the steering handle, and left and right transmission mechanisms for adjusting a rotation output to the crawler-type traveling device. Accordingly, the vehicle is turned by changing the output rotation of the left and right transmission mechanisms so as to have a preset rotation ratio.

[0003]

In a conventional crawler-type work vehicle, for example, when a vehicle body is loaded on a truck using a fin board, the posture of the body becomes unstable when the body rides on the fold board. If the steering wheel is rotated in such a state, the vehicle body turns in an unexpected direction by the operation of the left and right transmission mechanisms, which is dangerous. Similarly, when the vehicle climbs over a ridge in a field, the tip of the crawler floats up and the posture becomes unstable, and when the steering handle is rotated, unexpected movement may occur.

On the other hand, when the crawler type work vehicle is traveling on a slope, if the steering wheel is steered while the left and right rolling angles of the vehicle body are large, the vehicle body becomes unstable due to the action of the lateral G. In particular, when the steering wheel is steered significantly, the rotation of the crawler-type traveling device inside the turn stops, the vehicle body turns (lock-turn), and the left and right crawler-type traveling devices move in opposite directions. The vehicle body is rotated and driven by a super turning (spin turn), so that the vehicle body may fall down.

Therefore, in a crawler-type work vehicle configured to turn the vehicle body by adjusting the output rotation to the left and right crawler traveling devices according to the steering operation amount of the steering handle, the front-rear inclination angle of the vehicle body Or, when the posture of the car body is unstable due to the large left and right rolling angle,
A technical problem to be solved in order to prevent unexpected movement of the vehicle body in response to the steering operation of the steering wheel arises, and an object of the present invention is to solve this problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above object, and has a steering operation unit 1 for a vehicle body.
9 and a sensor 91 for detecting the operation amount of the steering operation unit 19
And a left and right crawler type traveling device C, and a left and right transmission mechanism 72 for adjusting output rotation to the crawler type traveling device C. In the crawler type work vehicle 10 configured to rotate the vehicle body by changing the output rotation of the mechanism 72 to a predetermined rotation ratio, a sensor 39 for detecting a front-rear inclination angle of the vehicle body is provided. When the change amount of the front-rear inclination angle of the vehicle body detected by the sensor 39 exceeds a predetermined angle, a control for restraining the start of shifting of the transmission mechanism 72 for a specified time in response to the steering operation of the steering operation unit 19. Crawler-type work vehicle provided with a section 90, a steering operation section 19 of a vehicle body, a sensor 91 for detecting an operation amount of the steering operation section, left and right crawler traveling apparatuses C, and a crawler traveling apparatus C Adjust the output rotation to the left and right A driving mechanism 72, wherein the output rotation of the left and right transmission mechanisms 72 is changed in speed according to the steering operation amount of the steering operation section 19 so as to have a preset rotation ratio, and the vehicle body is turned. Crawler type work vehicle 10 configured
A sensor 39 for detecting the front-rear inclination angle of the vehicle body is provided, and when the amount of change in the front-rear inclination angle of the vehicle body detected by the sensor 39 exceeds a predetermined angle, the output rotation ratio is changed to the right and left crawler rotation difference. Crawler-type work vehicle including a control unit 90 that corrects the vehicle so as to reduce the vehicle speed, and a vehicle body steering operation unit 19
A sensor 91 for detecting an operation amount of the steering operation unit, a left and right crawler traveling device C, and a left and right transmission mechanism 72 for adjusting output rotation to the crawler traveling device C; In the crawler-type work vehicle 10, the output rotation of the left and right transmission mechanisms 72 is shifted so as to have a preset rotation ratio in accordance with the steering operation amount of the operation unit 19, and the vehicle body is turned. A sensor 43 for detecting a left and right rolling angle of the vehicle body, and when the rolling angle of the vehicle body detected by the sensor 43 exceeds a predetermined angle, the steering operation unit 1
9, a crawler-type work vehicle including a control unit 90 that shifts the left and right transmission mechanisms 72 at a specified output rotation ratio or less, a vehicle body steering operation unit 19, A sensor 91 for detecting an operation amount of the steering operation unit, a left and right crawler traveling device C, and a left and right transmission mechanism 72 for adjusting output rotation to the crawler traveling device C; According to the steering operation amount, the output rotation of the left and right transmission mechanisms 72 is shifted so as to have a preset rotation ratio,
Crawler-type work vehicle 1 configured to turn a vehicle body
At 0, a sensor 43 for detecting the left and right rolling angle of the vehicle body is provided, and when the rolling angle of the vehicle body detected by the sensor 43 exceeds a predetermined angle, the output rotation ratio decreases the right and left crawler rotation difference. And a crawler-type work vehicle provided with a control unit 90 that corrects the above.

[0007]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIGS. 1 and 2 show an agricultural tractor 10 as an example of a crawler type work vehicle, in which a drive sprocket 12 is mounted on a rear axle 11 and a track frame 13 for rotatably supporting the drive sprocket 12.
, A driven sprocket 14 and a driven wheel 15 are pivotally connected to each other.
A crawler 16 is wound therebetween, and the front end of the track frame 13 is fixed to the vehicle body frame 17 to form a crawler type traveling device C.

In the figure, reference numeral 23 denotes a transmission case, and the crawler type traveling device C is supported on the left and right sides of the transmission case 23 and the transmission case 2
3, the crawler traveling device C
Is located behind the rear end of the vehicle body. As will be described later, the rotational power of the engine 46 is input to the transmission case 23, transmitted to the rear axle 11 after being shifted by a transmission in the transmission case 23, and the driving sprocket 12 rotates to drive the crawler 16. You.

In the vicinity of the driver's seat 18, a position lever 40 for setting the elevation position of the ground work machine 26, a cultivation depth adjustment dial 41 for setting the cultivation depth of the ground work machine 26, and a left and right direction of the ground work machine 26 are provided. A horizontal adjustment dial 42 and the like for setting the inclination are provided. A pitching angle sensor 39 for detecting an inclination angle of the vehicle body in the front-rear direction and a slope sensor 43 for detecting a horizontal rolling angle of the vehicle body are provided below the driver's seat 18.
Is installed.

[0010] On the other hand, a rotary operation type steering handle 19, which is a steering operation section of the vehicle body, is provided in front of the driver's seat 18. A steering handle shaft 20 is inserted into a steering handle column 21. Is equipped with a steering operation device 22. Further, as means for detecting the operation amount of the steering operation section of the vehicle body, a steering angle sensor 91 is provided on the steering handle shaft 20, and the rotation angle of the steering handle 19 is detected by the steering angle sensor 91. Furthermore,
A brake pedal 44 is provided on the right side of the steering handle column 21, and a clutch pedal 45 is provided on the left side of the steering handle column 21. Note that a controller 90 as a control unit is provided below the driver's seat 18.

A ground working machine 26 such as a rotary is connected to a rear portion of the vehicle body via a link mechanism 25. The link mechanism 25 includes a top link 27 and left and right lower links 28, 28. Lift arm 29,2
9 and the lower link 28, 28 with the lift rod 30,
By connecting the lift arm 29 by driving the lift cylinder 32, the lift rod 30,
The lower links 28, 28 move up and down via 30. In this way, the ground working machine 26 moves up and down around the tip ends of the lower links 28, 28 as the center of rotation.

A lift arm angle sensor 33 is provided at the rotation base of the lift arm 29 as a sensor for detecting the elevation position of the ground work machine 26. The lift arm angle sensor 33 detects the rotation angle of the lift arm 29. The height of the ground work machine 26 is detected and calculated. A rear cover 35 is rotatably attached to the rear end of the main cover 34 of the ground work machine 26.
5 to detect the turning angle of the ground work machine 26 and control the plowing depth.

On the other hand, as an actuator for changing the inclination of the ground work machine 26 in the left-right direction with respect to the vehicle body, a rolling cylinder 3
7, the rolling angle of the ground work machine 26 can be changed by extending and contracting the rolling cylinder 37 to change the lift amount of the lower link 28 between left and right.
A stroke sensor 38 is provided adjacent to the rolling cylinder 37. The stroke sensor 38 detects the length of expansion and contraction of the rolling cylinder 37, measures the rolling angle of the ground work machine 26 with respect to the vehicle body, and adjusts the horizontal adjustment dial. The rolling cylinder 37 is driven to expand and contract in accordance with the set value of 42, so that the rolling control of the ground work machine 26 can be performed.

Next, the tractor 10 shown in FIGS.
The configuration of the power transmission control device will be described. The transmission case 23 is a front transmission case 23a.
, A mid-mission case 23b and a rear transmission case 23c.
Rear axle cases 47, 47 are connected to the left and right sides of the vehicle to support the crawler type traveling device C. A power input shaft 48 projects from the front of the front transmission case 23a, and an engine rotation output shaft 49 and a power input shaft 48 surrounded by the body frame 17 are coaxially connected.

The rotational power of the engine 46 is input from the engine rotational output shaft 49 and the power input shaft 48 into the front transmission case 23a, first transmitted to the lower part of the case by the reduction gear 50, and then transmitted to the rear main clutch 51. And transmitted to a hydraulic pump 52 provided at the front of the front transmission case 23a. The power that is turned on and off by the main clutch 51 is transmitted to the main transmission 53 and the subtransmission 5 in the mid-transmission case 23b.
4, a pinion shaft 5 which is appropriately decelerated and becomes an auxiliary transmission output shaft
5 is transmitted to the rear transmission case 23c.

The main transmission 53 includes a main transmission drive shaft 56.
Between the first speed to the third speed and the main speed
A so-called key shift in which power is transmitted through any one of the gear sets 58 by providing a gear set 58 having a reverse speed and operating a slide key 59 provided in the main speed driven shaft 57 back and forth. It is a type transmission mechanism.

The auxiliary transmission 54 is provided with an auxiliary transmission drive shaft 60 on the extension of the main transmission drive shaft 56, and the auxiliary transmission drive shaft 60 is provided with two-stage gears 61 for "high speed" and "low speed". 6
2 is provided, while a sub-transmission driven shaft, that is, the pinion shaft 55 is provided on an extension of the main transmission driven shaft 57, and the pinion shaft 55 is engaged with the two-stage gears 61 and 62 by a sliding two-stage gear 63. The transmission is provided by a constant mesh type gear provided with.

Reference numeral 64 denotes a PTO transmission shaft, which transmits power to a rear PTO shaft 66 projecting from a rear portion of the rear transmission case 23c via a PTO transmission 65 provided in the rear transmission case 23c.

A support shaft 68 is provided between the left and right side walls of the rear transmission case 23c, and a bevel gear 69 that meshes with the pinion shaft 55 is spline-fitted at a position slightly deviated from the center of the support shaft 68. A brake disk 70 is provided at a position substantially opposite to the left and right.
Then, the brake pedal 44 and the brake disc 70 are connected by a link mechanism (not shown). Since the power transmission control device shown in the present embodiment does not have a rear differential gear, it is sufficient to dispose the brake disc 70 only at one position on the left and right, and a brake pedal 44 is provided on the right side of the steering handle column 21. Therefore, by arranging the brake disk 70 on the right side, the link mechanism can be simplified.

The brake disk 70 is pressed by the depression operation of the brake pedal 44, and the rotation of the support shaft 68, that is, the rotation of the right and left crawlers 16, 16 is braked. A reduction gear set 71 is provided at both left and right ends of the support shaft 68 to transmit the rotation of the bevel gear 69 to a forward / reverse switching device 72 in the rear axle case 47.

The rear axle case 47 is a substantially cylindrical casting case, and has a wet multi-plate reverse clutch 74 (inside the vehicle body) and a drive shaft 73 driven through the reduction gear set 71. Forward rotation clutch 75 (outside the vehicle)
And a so-called two-stage planetary gear mechanism 76 having a counter gear is provided outside the forward rotation clutch 75 to constitute a transmission mechanism for shifting the output rotation.
The forward rotation clutch 75 includes an internal spring 77.
, So that it is always crimped. In this state,
A drive-side sun gear 78 integral with the drive-side disk of the forward rotation clutch 75 and a carrier 79 integral with the planetary gears and the driven-side disk meshing therewith rotate integrally with the drive-side sun gear 78 as a center, The rotation of the bevel gear 46 is transmitted from the driving sun gear 78 to the driven sun gear 80 at a one-to-one rotation ratio.

When pressure oil is supplied to the piston portion 81 of the reverse rotation clutch 74, the pressure of the disk of the normal rotation clutch 75 is gradually released in a reciprocal manner, so that the drive side disk and the driven side disk are disengaged from each other. A rotation difference is generated between them, and accordingly, the rotation transmitted to the driven-side sun gear 80 is reduced. When the pressure oil is continuously fed to the piston portion 81 and the amount of movement of the piston is increased toward the inside of the vehicle body in the figure, the press-fit of the disk of the forward rotation clutch 75 is completely released, and the rotation of the driven side sun gear 80 becomes zero. , The rotation of the crawler 16 stops, and the clutch enters the disengaged state. If the pressurized oil is further sent to the piston portion 81 after the disengagement state, the drive-side disk and the driven-side disk of the reverse rotation clutch 74 are gradually pressed, and the carrier 7
9 is transmitted to the driven-side sun gear 80 via the two-stage planetary gear 76. Therefore, the rotation of the bevel gear 69 is transmitted to the driven-side sun gear 80 by reverse rotation, and the rotation of the crawler 16 is driven in reverse rotation. The reverse rotation clutch 7
4. An adjusting means capable of arbitrarily adjusting the output rotation is constituted by the forward rotation clutch 75 and the like.

The rotation ratio at the time of the reverse rotation is set to approximately 30% of the rotation at the time of the forward rotation. The means for operating the reverse rotation clutch 74 is interlocked with the turning operation of the tractor 10. The configuration may be such that only the crawler 16 inside the turning is reversed, or the left and right reversing clutches 74, 74 may be simultaneously pressed to move the vehicle backward. In such a case, the clutch can be connected at full pressure at low speed, and the clutch can be used while sliding slightly at high speed, so that the traveling speed can be controlled so as not to become too high during reverse travel. Further, as will be described later, the depression amount of the clutch pedal 45 is detected, and the forward rotation clutch 75, the reverse rotation clutch 74, the two-stage planetary gear mechanism 7 are detected.
If the disengaged state is maintained by using the transmission mechanism composed of 6, the main clutch 51 described above can be eliminated.

The driven-side sun gear 80 is provided with a cover 8 that shields an outer opening of the rear axle case 47.
2 and the lid 8
2 is made of the same casting as the rear axle case 47, and has a bolt hole 8 for connection with the rear axle case 47.
An outer lid portion 82a having 3, 83...
Inner cover 82 that is attached to the inner surface of the
b and a ring gear 84 interposed between the outer lid portion 82a and the inner lid portion 82b. A pack-shaped space 85 is formed between the outer lid 82a and the inner lid 82b,
A planetary gear mechanism 87 for reducing the rotation of the input shaft 86 and transmitting the rotation to the output shaft, that is, the rear axle 11, is provided in the space 85.

Reference numeral 88 denotes a rotation detecting gear.
A non-contact type rotation detection sensor 89 is arranged close to the rotation detection gear 88 so that output rotations to the right and left crawlers 16 and 16 can be detected. Also,
The planetary gear mechanism 87 in the lid 82 can arbitrarily change the reduction ratio according to the specification change of the tractor 10, such as when changing between the wheel specification and the crawler specification or when changing the wheel diameter of the wheel specification. A mechanism that can be changed may be used.

FIG. 6 is a block diagram of a control system. Inside the controller 90, which is a control unit, a CPU for processing various information, a RAM for storing various sensor values and set values, a control program, and the like. The input section of the controller 90 has setting signals for the position lever 40, the tillage depth adjustment dial 41, the horizontal adjustment dial 42, etc., and the lift arm angle sensor 33, the pitching angle sensor 39, and the like. Detection signals from the slope sensor 43, the steering angle sensor 91, and the like are input.

Also, based on these input signals, an up solenoid or a down solenoid of the control valve for the lift cylinder 32 is output from the output of the controller 90.
Control valve for the rolling cylinder 37, an extension solenoid or a contraction solenoid, a brake disc 7
0 control valve brake solenoid, left forward / reverse switching device 72 control valve clutch solenoid, right forward / reverse switching device 72 control valve clutch solenoid, engine speed display section 99
Output an operation signal to the like.

FIG. 7 shows the engine speed display section 99. When the shift position is in the low speed range or the first high speed or the second high speed based on the detection signals of the main shift position sensor 96 and the auxiliary shift position sensor 97, the engine speed is displayed. The controller 90 calculates the engine speed based on the detection signal of the speed sensor 98, and displays the engine speed on the engine speed display unit 99. On the other hand, when the shift position is shifted to the third or higher speed, the controller 90 calculates the running speed of the vehicle body based on the detection signal of the vehicle speed sensor 95, and displays the vehicle speed on the engine speed display section 99. Thus, in the work area, the engine speed is displayed to notify the operator of the engine state at the time of work, and in the general travel area, the vehicle speed is displayed to promote the safety of traveling. An apparatus can be provided.

FIG. 8 shows the magnitude of the clutch current (clutch cylinder pressure) output from the controller 90 and the crawler 1.
6 shows the relationship with the rotation state, for example, when the clutch current is 0 A in the forward running state, the clutch cylinder pressure is 0 kg / c.
m ² , the forward rotation clutch 75 is connected at full pressure, and the crawler 16 is driven to rotate in the forward direction. Controller 90
When the clutch current is gradually increased to increase the clutch cylinder pressure output to the clutch solenoid of the forward / reverse switching device 72, the forward rotation clutch 75 slips when the clutch current is around 0.2 A, and the crawler 16 moves forward. The rotation in the direction decreases. When the clutch current increases to around 0.4 A, the clutch cylinder pressure becomes about 10 kg / cm ^2, and both the forward rotation clutch 75 and the reverse rotation clutch 74 maintain the disengaged state. For this reason, the rotational power transmitted from the pinion shaft 55 to the support shaft 68 is not transmitted to the rear axle 11, and the crawler 16 is not driven.

In this state, when the clutch current is further increased to about 0.6 A, the reverse rotation clutch 74 is engaged while slipping, and the crawler 16 starts rotating in the reverse direction in the half-clutch state. When the clutch current is increased to around 0.8 A, the clutch cylinder pressure becomes 20 kg / cm ² and the reverse rotation clutch 74 is connected at full pressure. Therefore, the support shaft 6 is
8 is transmitted to the rear axle 11 in reverse, and the crawler 16 is driven to rotate in the reverse direction.

As described above, by changing the clutch current output from the controller 90, the clutch cylinder pressure of the forward / reverse switching device 72 is increased or decreased, and the connection state of the forward clutch 75 and the reverse clutch 74 is continuously changed. Change. That is, the clutch of the forward / reverse switching device 72 does not have a general neutral position (neutral), and has a continuous driving torque between forward rotation and reverse rotation while continuously changing the rotation direction and rotation speed of the crawler 16. It can be adjusted appropriately and arbitrarily.

The steering operation (rotation operation) of the steering handle 19 is detected by the steering angle sensor 91, and the forward / reverse switching device 72 of one of the forward / reverse switching devices 72 is operated in accordance with the steering operation amount (change of the steering angle). By controlling the clutch and decelerating the rotation of the crawler 16 inside the turning, the vehicle body can be turned by giving a rotation difference to the right and left crawlers 16, 16. On relatively hard ground, the crawler 16 inside the turn may be stopped or reversed, causing the vehicle to turn sharply.However, if the rotation of the crawler 16 is locked during the turn, the ground is likely to be rough, so usually the forward and reverse rotation inside the turn The vehicle body is slowly turned by sliding the clutch of the switching device 72 to reduce the rotation of the crawler 16 inside the turn.

For example, in the forward running state, when the clutch current is 0 A, that is, when the clutch cylinder pressure is 0 kg / cm ² , the left and right forward rotation clutches 75 and 75 are connected at full pressure, and both the left and right crawlers 16 and 16 are both connected. It is driven to rotate forward.
Then, when the steering operation of the steering handle 19 is performed, the clutch current to the clutch solenoid of the forward / reverse switching device 72 on one side (the inside of the rotation) is gradually increased, and the clutch cylinder pressure is increased, and the clutch current is increased. At about 0.2A, slippage occurs in the forward rotation clutch 75,
Since the rotation of one of the crawlers 16 in the forward direction decreases, a rotation difference occurs between the left and right crawlers 16, 16 and the vehicle body turns. By maintaining this clutch slip state, the vehicle body turns slowly without breaking the ground (brake turn)
Can be done.

When the clutch current for the clutch solenoid of one of the forward / reverse switching devices 72 (inside the turning) is increased to about 0.4 A, the clutch cylinder pressure becomes about 10 kg / cm ² , and the one forward clutch 75 Both the reverse clutch 74 and the reverse rotation clutch 74 maintain the disengaged state. For this reason, the rotational power transmitted from the pinion shaft 55 to the support shaft 68 is not transmitted to the one rear axle 11, the rotation of the crawler 16 inside the turn is locked, the turning radius is reduced, and the vehicle body is pivotally turned ( Lock turn).

Further, when the clutch current for the clutch solenoid of one of the forward / reverse switching devices 72 (inside of turning) is increased to about 0.8 A, the clutch cylinder pressure becomes 20 kg / cm ^2, and The clutch 74 is connected at full pressure. For this reason, the rotational power transmitted from the pinion shaft 55 to the support shaft 68 is reversed and transmitted to one of the rear axles 11, and the crawler 16 inside the turning is driven to rotate backward. Therefore, the left and right crawlers 16 and 16 rotate in opposite directions to each other to minimize the turning radius, and the vehicle body can be turned in a spin turn.

Here, as shown in FIG. 9, for example, when the tractor 10 is loaded on the truck 102 using the oyster plate 101, the vehicle body rises at the moment when the tip of the crawler 16 rides on the oyster plate 101. At this time, if the steering handle 19 is steered rapidly, the crawler traveling device C may rotate left and right differently due to the operation of the left and right transmission mechanisms, and the crawler 16 may come off from the breathing board 101. Also, the crawler 16
When the tip of the truck rides on the bed of the truck 102,
The posture of the vehicle body becomes unstable because the front half of the crawler traveling device C is lowered from the raised state to the front side and lands on the loading platform. Turning in the wrong direction is dangerous.

Therefore, as shown in FIG. 10, when the pitching angle of the vehicle body in the front-rear direction (pitching angle) detected by the pitching angle sensor 39 exceeds a predetermined angle (eg, about 15 degrees) (t ₁ ), Even if the steering operation of the steering handle 19 is performed, the controller 90 does not output a signal current to the clutch solenoid for the forward / reverse switching device 72 for a specified time (about 10 seconds). Accordingly, the shift start of the transmission mechanism is restrained for a specified time, and
Limit the steering angle at the moment of getting on 01. Then, when the pitching angle of the vehicle body returns to 0 degrees (t ₂ ), the signal current from the controller 90 to the clutch solenoid for the forward / reverse switching device 72 is stopped for the specified time (about 10 seconds). Therefore, the shift start of the transmission mechanism is restrained for a specified time, and the crawler traveling device C limits the steering angle at the moment when the crawler traveling device C gets on the bed of the truck 102 from the fold plate 101.

As described above, when the amount of change in the pitching angle of the vehicle body greatly changes, it is possible to avoid danger by judging that the vehicle body is in an unstable posture and restraining the turning operation. Although not shown, the pitching angle sensor 39 is also used when the vehicle crosses the ridge in the field.
From the sudden change in the detection value, it is determined that the tip of the crawler 16 is raised and the posture of the vehicle body is unstable, and even if the steering operation of the steering handle 19 is performed, the controller 90 controls the forward / reverse switching device 72 The signal current to the clutch solenoid is stopped to prevent the danger of the vehicle body turning in an unexpected direction of the operator.

When the steering operation of the steering handle 19 is performed when the pitching angle of the vehicle body exceeds a predetermined angle, the controller is operated to correct the rotation difference between the left and right crawlers 16 and 16 so as to decrease. It is also possible to control the signal current from 90 to the clutch solenoid for the forward / reverse switching device 72. In such a case, when the pitching angle of the vehicle body changes greatly and the posture is unstable, even if the vehicle body tries to perform a turning operation by steering operation of the steering handle 19, the left and right crawlers 16, 16 are moved. And the vehicle body returns to the straight running state, and safety can be ensured.

On the other hand, as shown in FIG. 11, for example, when the tractor 10 runs on a sloped ground in a downward right position, when the steering wheel 19 is steered while the left and right rolling angles of the vehicle body are large, the lateral G action causes The body becomes unstable. Therefore, when the left and right rolling angle of the vehicle body detected by the slope sensor 43 exceeds a predetermined angle, the signal current from the controller 90 to the clutch solenoid for the forward / reverse switching device 72 is reduced as shown in FIG. Reduce to current.

Normally, the clutch current is increased with an increase in the steering angle, and the vehicle body makes a gentle turn (brake turn) at around 0.2 A. As shown by the two-dot chain line in FIG.
At around 0.4A, the vehicle makes a pivot turn.
Furthermore, when the steering angle increases and the clutch current rises to around 0.8 A, the reverse rotation clutch 74 inside the turn is connected at full pressure, and the vehicle body makes a spin turn. However, when the left and right rolling angles of the vehicle body are large, the clutch current can be suppressed to about 0.3 A as shown by the solid line in FIG.
5 is maintained in a state in which slippage has occurred, and a sudden turn of the vehicle body can be restrained to prevent a fall or the like.

When the steering angle of the steering wheel 19 is increased when the rolling angle of the vehicle body exceeds a predetermined angle, the controller is operated to correct the rotation difference between the left and right crawlers 16 and 16 so as to decrease. It is also possible to control the signal current from 90 to the clutch solenoid for the forward / reverse switching device 72. In such a case, when the rolling angle of the vehicle body is large and the posture is unstable, the rotational difference between the left and right crawlers 16 and 16 can be increased even when the vehicle body attempts to perform a turning operation by the steering operation of the steering handle 19. And the vehicle body returns to the straight traveling state, and safety can be ensured.

The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified ones.

[0044]

As described in detail in the above-described embodiment, the invention according to claim 1 is characterized in that when the amount of change in the front-rear inclination angle of the vehicle body exceeds a predetermined angle, the steering operation unit is moved. The start of shifting of the transmission mechanism is suppressed for a specified time in response to the steering operation.
The danger that the vehicle body turns in an unexpected direction of the operator can be prevented.

According to the second aspect of the present invention, when the amount of change in the front-rear inclination angle of the vehicle body exceeds a predetermined angle, the output rotation ratio of the left and right transmission mechanisms is changed with respect to the steering operation of the steering operation section. Is corrected so as to reduce the crawler rotation difference, so that the turning operation of the vehicle body becomes small and stability can be secured.

According to the third aspect of the present invention, when the left and right rolling angles of the vehicle body exceed a predetermined angle, the left and right transmission mechanisms are operated at a specified output rotation ratio or less with respect to the steering operation of the steering wheel. Since the speed is changed, the turning of the vehicle body on a slope (rock turn) or the turning of a super-powered ground (spin turn) is suppressed, and the vehicle body can be prevented from tipping over.

According to a third aspect of the present invention, when the left and right rolling angle of the vehicle body exceeds a predetermined angle, the output rotation ratio of the left and right transmission mechanisms is changed by the left and right crawler rotation difference with respect to the steering operation of the steering wheel. Since the correction is made so as to decrease, the turning operation of the vehicle body becomes small and the stability can be secured.

Thus, a stable steering operation can be ensured even by an unskilled operator, which can contribute to an improvement in safety.

[Brief description of the drawings]

 The figure shows an embodiment of the present invention.

FIG. 1 is a side view of a crawler type tractor.

FIG. 2 is a rear view of the crawler type tractor.

FIG. 3 is a diagram showing a configuration of a power transmission control device in a transmission case.

FIG. 4 is a diagram showing a configuration of a power transmission control device in a rear axle case.

FIG. 5 is a diagram showing a power transmission path.

FIG. 6 is a block diagram of a control system.

FIG. 7 is a front view of an engine speed display unit.

FIG. 8 is a graph showing the relationship between clutch cylinder pressure and vehicle speed.

FIG. 9 is an explanatory view of a state in which a tractor is loaded on a truck by using an ayumi board.

FIG. 10 is a graph showing a relationship between a change in pitching angle and a steering operation.

FIG. 11 is an explanatory view showing a state in which a tractor travels on a slope.

FIG. 12 is a graph showing a relationship between a steering angle and a clutch current on a slope.

[Explanation of symbols]

 Reference Signs List 10 tractor 16 crawler 19 steering handle 39 pitching sensor 43 slope sensor 72 forward / reverse switching device 74 reverse rotation clutch 75 forward rotation clutch 76 two-stage planetary gear mechanism 90 controller 91 steering angle sensor C crawler type traveling device

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor: Masayuki Takahashi 1-Yakura, Tobe-cho, Iyo-gun, Ehime Pref.

Claims (4)

[Claims] 1. A steering operation unit 19 of a vehicle body, a sensor 91 for detecting an operation amount of the steering operation unit 19, a left and right crawler traveling device C, and an output rotation to the crawler traveling device C are adjusted. And a right and left power transmission mechanism 72 that changes the output rotation of the left and right power transmission mechanism 72 to a preset rotation ratio in accordance with the amount of steering operation of the steering operation section 19 to turn the vehicle body. In the crawler-type work vehicle 10 configured to cause the vehicle, a sensor 39 for detecting a front-rear inclination angle of the vehicle body is provided, and when a change amount of the vehicle front-rear inclination angle detected by the sensor 39 exceeds a predetermined angle, A crawler-type work vehicle, comprising: a control unit (90) for checking the start of shifting by the transmission mechanism (72) for a specified time in response to a steering operation of the steering operation unit (19). 2. A steering operation unit 19 for a vehicle body, a sensor 91 for detecting an operation amount of the steering operation unit, a left and right crawler traveling device C, and an output rotation to the crawler traveling device C are adjusted. A left and right transmission mechanism 72;
In the crawler-type work vehicle 10 configured to rotate the vehicle body by changing the output rotation of the left and right transmission mechanisms 72 to a predetermined rotation ratio in accordance with the steering operation amount of the vehicle body, A sensor 39 for detecting the front-rear inclination angle is provided, and when the amount of change of the front-rear inclination angle of the vehicle body detected by the sensor 39 exceeds a predetermined angle, the output rotation ratio is corrected so that the difference between the left and right crawler rotations is reduced. A crawler-type work vehicle, comprising: 3. A steering operation unit 19 for a vehicle body, a sensor 91 for detecting an operation amount of the steering operation unit, a left and right crawler traveling device C, and an output rotation to the crawler traveling device C are adjusted. A left and right transmission mechanism 72;
In the crawler-type work vehicle 10 configured to rotate the vehicle body by changing the output rotation of the left and right transmission mechanisms 72 to a predetermined rotation ratio in accordance with the steering operation amount of the vehicle body, A sensor 43 for detecting a right and left rolling angle is provided. When the rolling angle of the vehicle body detected by the sensor 43 exceeds a predetermined angle, the left and right transmission mechanisms 72 are actuated in response to a steering operation of the steering operation unit 19. A crawler-type work vehicle comprising: a control unit 90 that shifts the speed at or below a specified output rotation ratio. 4. A steering operation unit 19 for a vehicle body, a sensor 91 for detecting an operation amount of the steering operation unit, a left and right crawler traveling device C, and an output rotation to the crawler traveling device C are adjusted. A left and right transmission mechanism 72;
In the crawler-type work vehicle 10 configured to rotate the vehicle body by changing the output rotation of the left and right transmission mechanisms 72 to a predetermined rotation ratio in accordance with the steering operation amount of the vehicle body, A control unit that corrects the output rotation ratio so that the difference between the left and right crawler rotations is reduced when the sensor detects a left and right rolling angle and the rolling angle of the vehicle detected by the sensor 43 exceeds a predetermined angle; A crawler-type work vehicle comprising: