JP3579983B2 - Tractor auto brake controller - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an automatic brake control device for a tractor, and can be used as an automatic brake control device that automatically brakes a steering brake by steering a steering handle.
[0002]
2. Description of the Related Art
The auto-brake control is such that when the driver turns the tractor on a ridge or the like, the driver operates the steering handle to reach a certain turning angle, and this automatically controls the rear wheel on the turning side. It is the one that applies the directional brake. In such auto-brake control, the steering brake is released immediately before the end of the turn, and the vehicle shifts from the turn to the straight running state.The steering brake works as a strong braking force that is full of the braking force, and this is completely applied at the end of the turn. If the braking force changes to a state in which the braking force does not work, the direction of the vehicle body from turning to straight running will not be stable, and steering correction such as excessive turning and returning will be required, and a smooth and accurate straight traveling state It is difficult to make the transition to.
[0003]
[Means for Solving the Problems]
According to the present invention, steering brakes 2, 2 for braking left and right rear wheels 10, 10 are provided separately for the left and right wheels, and these steering brakes 2, 2 are provided with hydraulic actuators 25, 25, respectively. In the tractor configured to operate the solenoids 25 and 25 by the electromagnetic proportional solenoid valves 28 and 28, the steering brakes 2 and 2 are turned by depressing a brake pedal, and the steering wheel 1 is turned. A brake mode switch 38 is provided for switching between an auto-brake mode for operating the inner steering brake 2 and an auto-lift brake mode for raising the steering brake 2 and the lift arm 17 inside the turn by rotating the steering handle 1. , Set the brake mode switch 38 When the steering wheel 1 is turned to a predetermined full steering angle α1 when the mode is switched to the auto brake mode or the auto lift brake mode, a strong braking force acts on the steering brake 2, and only a fixed angle from the angle is applied. A tractor auto-brake control device, further comprising control means for applying a constant braking force to the steering brake 2 which is weaker than the braking force when the steering handle 1 is returned .
[0004]
[Action]
When the brake mode changeover switch 38 is switched to the auto-brake mode or the auto-lift brake mode, the steering brake 2 is braked by the steering of the steering handle 1, so that the steering turning of the vehicle body is accurately performed. At this time, the steering angle α of the steering wheel 1 becomes a full steering angle α1 that cannot be steered any more, and the braking force F corresponding thereto also acts as the highest strong braking force F1, and is almost constant. The steering turn is performed based on the turning radius.
[0005]
【The invention's effect】
Near the end of the turn, the return operation of the steering handle 1 reaches a fixed angle range α2 smaller than the full steering angle α1 . Then, the hydraulic pressure of the hydraulic actuator 25 is adjusted by the electromagnetic proportional solenoid valve 28, and the braking force F of the steering brake 2 inside the turning is also switched from the strong braking force F1 to the weak and constant braking force F2. Steering to straight ahead is performed slowly. For this reason, the steering turning is smoothly and accurately performed, so that correction due to excessive turning of the steering handle 1 or the like can be reduced, and fine adjustment between the vehicle and traveling on an adjacent ground can be easily performed.
[0006]
【Example】
The tractor body 3 has an engine body 4 at a front part, a clutch housing 5 and a transmission case 6 are connected at a rear part to form a rigid body, and a front axle bracket 7 integrated with a front part of the engine body 4 has a left and right side. A front axle housing is provided in which a pair of front wheels 8 are steerably mounted on a shaft. A rear axle housing 9 is provided on both left and right sides of a rear transmission case 6, and rear wheels 10 are mounted on both side ends. The vehicle can travel by driving these front wheels 8 and rear wheels 10.
[0007]
The front wheel 8 is steerably linked by a steering handle 1 supported on a steering post 11, and a steering angle α of the steering handle 1 is detected by a steering sensor 12. 13 is a hood, 14 is a fender, and 15 is a cockpit. Reference numeral 16 denotes a hydraulic case on the transmission case 6, which is configured to rotate the lift arm 17 up and down by expansion and contraction of an internal hydraulic cylinder.
[0008]
A pair of left and right steering brakes 2 are provided on the left and right rear axle housings 9 and brake the rotation of the rear wheels 18 from the rear differential device 26 that transmits to the rear wheels 10 to the rear wheels 10. Disc brakes are provided on the left and right differential shafts 19. A pair of left and right brake petals 20 are on a floor step 21, and are configured to be able to brake the rear wheel 10 by rotating a brake arm 23 of the steering brake 2 via a link rod 22. Further, the brake arm 23 is interlocked to receive the operation of the hydraulic actuator 25 in the hydraulic pack 24, and the steering brake 2 is also braked by the hydraulic actuator 25.
[0009]
The steering brake 2 is input to a controller CPU having a microcomputer via a brake sensor 27 that detects the amount of operation of the brake petal 20 when the brake pedal 20 is depressed. An electromagnetic proportional solenoid valve 28 is output to control the hydraulic pressure of a hydraulic circuit 29 by a hydraulic pump P to operate the hydraulic actuator 25 for braking. Reference numeral 30 denotes a damper of the brake petal 20, and reference numeral 31 denotes an equalizer valve for equalizing hydraulic pressure to the left and right hydraulic actuators 25 of the hydraulic circuit 29. A in the hydraulic pack 24 is a pump port, which raises oil pressure from the hydraulic pump P into the actuator cylinder 32 to operate the actuator 25, which is a piston, against the spring 33. T is a tank port.
[0010]
Each of the steering brakes 2 is configured in a garring configuration. The link 34 is pulled by the hydraulic actuator 25, and a pair of cam disks 36 that sandwich the ball 35 in the axial direction are rotated in opposite directions. The brake disc 37 is pressed to brake the rotation of the differential shaft 19. The steering brake 2 is pressure-controlled by an electromagnetic proportional solenoid valve 28 according to the depression force of the brake petal 20 and the amount detected by the brake sensor 27.
[0011]
As inputs of the controller CPU, in addition to the steering sensor 12, a brake mode changeover switch 38 and a front wheel drive mode changeover switch 39 are provided. The brake mode changeover switch 38 includes a petal mode (1) for interlocking with the link rod 22 and braking the steering brake 2 on the left / right selection side detected by the brake sensor 27 when the steering brake petal 20 is depressed. An auto-brake mode (2) in which the steering sensor 2 detects a steering turning angle of the steering handle 1 equal to or greater than a predetermined value to brake the steering brake 2 on the turning side, and the same as the auto-brake mode (2). Can be switched to the auto-lift brake mode 3 in which the solenoid valve 40 for raising the lift arm 17 is output.
[0012]
The front-wheel drive mode changeover switch 39 is provided with a transmission that transmits power to the front wheels 8 and a switching clutch 41 in the transmission in the transmission case 6, and switches the switching clutch 41 to the neutral position. The front wheel 8 is almost the same as the rear wheel 10 by turning on the 2WD mode (4) in which the transmission is performed to the rear wheel 10 without transmitting to the front wheel 8 and the switching clutch on the 4WD side is engaged. A normal 4WD mode (5) for transmitting to the speed, and a double speed for engaging the double speed side switching clutch for transmitting the power to the front wheels 8 to approximately twice the speed of the rear wheels 10 for transmission. Switching to the 4WD mode (6) can be selected. The switching operation of the switching clutch 41 is operated via a hydraulic actuator by a solenoid valve 42 in each mode. 43 is a vehicle speed sensor for detecting the vehicle speed.
[0013]
In such a configuration, the brake mode changeover switch 38 is switched to the auto brake mode (2) or the auto lift brake mode (3), and the front wheel drive mode changeover switch 39 is set to one of the modes (4) to (6). When the traveling and the steering turn are performed by selecting the steering wheel, the steering brake 2 on the steering side is braked by the detection of the steering sensor 12 when the steering angle α of the steering handle 1 reaches the turning angle. At this time, at the time of turning, the steering angle α of the steering handle 1 has reached the full steering angle α1 and the braking force F of the steering brake 2 has also become a strong braking force F1. When the steering angle α is returned to a certain angle range α2, the hydraulic pressure of the hydraulic actuator 25 is adjusted by the electromagnetic proportional solenoid valve 28 with the return of the steering angle α, and gradually. The pressure is reduced to the weak braking force F2. Therefore, at the end of the turn, the transition to the straight traveling range is performed smoothly, and the automatic steering turn is facilitated.
[0014]
Note that such automatic adjustment of the braking force of the steering brake 2 can be similarly performed in the petal (1). The difference between the steering turning control in FIG. 5 and the above example is that when turning by the auto-brake control or the double speed 4WD control, the control is suppressed by the vehicle speed. In addition, the restraint is appropriately performed based on the shift position of the auxiliary transmission and a preset theoretical vehicle speed.
[0015]
When the vehicle is shifted to the high-speed position by the sub-transmission, such as when traveling on the road, or even when the sub-transmission is not at the high-speed position, the vehicle speed is set to the set value of the front wheel speed increase (medium speed, etc.) ), The speed increase of the front wheels 8 (double speed 4WD) is cut. Even if the vehicle speed is not equal to or higher than the front wheel acceleration setting, if the vehicle speed is equal to or higher than the automatic brake setting (eg, about 3 km / h) during the front wheel acceleration (double speed 4WD) control, the automatic brake control is performed. However, the automatic brake control is performed at a low speed below the setting.
[0016]
That is, when traveling on the road, the front wheel speed increase (double speed) 4WD and the auto brake control are both cut off, and in the medium speed work that requires only the front wheel speed increase such as during the scraping work, only the auto brake control is cut off. In low-speed work such as rotary work, front wheel acceleration and auto-brake control can be used together to perform proper operation check and improve safety.
[Brief description of the drawings]
FIG. 1 is a graph of a braking force of a steering brake.
FIG. 2 is a block diagram of steering rotation control of the tractor.
FIG. 3 is a side view of the tractor.
FIG. 4 is a cross-sectional view of the steering brake unit.
FIG. 5 is a flowchart of steering and turning control according to another embodiment.
[Explanation of symbols]
Reference Signs List 1 steering handle 2 steering brake α steering angle α1 full steering angle α2 constant angle range F braking force F1 strong braking force F2 weak braking force

Claims (1)

Steering brakes 2, 2 for braking the left and right rear wheels 10, 10 are provided separately for left and right, and these steering brakes 2, 2 are provided with hydraulic actuators 25, 25, and these hydraulic actuators 25, 25 are provided. In a tractor configured to be operated by electromagnetic proportional solenoid valves 28, 28, a steering mode in which the steering brakes 2, 2 are operated by depressing a brake pedal, and a steering operation inside a turning operation by turning a steering handle 1 are performed. A brake mode changeover switch 38 is provided for switching between an auto-brake mode for operating the brake 2 and an auto-lift brake mode for raising the steering brake 2 and the lift arm 17 inside the turn by rotating the steering handle 1. Set the changeover switch 38 When the steering wheel 1 is turned to a predetermined full steering angle α1 while the mode is switched to the key mode or the auto-lift brake mode, a strong braking force acts on the steering brake 2, and the steering wheel is turned by a certain angle from that angle. 1. A tractor auto-brake control device, further comprising control means for applying a constant braking force to the steering brake 2 when the returning operation of the steering wheel 1 is weaker than the braking force .

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