JPH0815A - Turning control unit in four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To provide a turning control unit designed to improve turning performance, reduce the unevennesses of turning position and facilitate butt finishing, improved in workability, equipped with such a control section as to elevate a working machine when steering angle comes to a set value or larger and then to actuate another means. CONSTITUTION:This control unit is so designed as to be equipped with a means to detect steering angle, a means to raise front wheel rotational speed in turning, a means to brake the rear wheel inside the turning in turning, and a means to elevate a working machine in turning. When the steering angle comes to a set value or larger, it is determined that the machine body runs to a turning state. Then, the means to elevate the working machine is first actuated to automatically elevate it. On elevating the working machine to the uppermost position, the other two means are actuated to shorten machine body turning time and reduce machine body turning radius.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning control device for a four-wheel drive vehicle, and more particularly to detecting the steering angle of a steering wheel to accelerate the front wheels, brake the rear wheels on the inside of turning, and work machines. The present invention relates to a turning control device in a four-wheel drive vehicle configured to raise the vehicle.

[0002]

2. Description of the Related Art Conventionally, a pair of brake devices, which can be operated independently left and right, are provided on the rear wheels of a four-wheel drive vehicle such as a tractor.
Only one brake pedal is pressed to control the rear wheels on the inside of the turn, reducing the turning radius of the machine.

Further, when a device for increasing the rotation speed of the front wheels to approximately twice that of the rear wheels is provided and the machine body is turned during the plowing work, the rotation speed of the front wheels is increased to shorten the turning time. There is. Further, an elevating switch for raising the working machine such as a rotary to the highest position is provided, and is raised to the highest position so that the working machine is not dragged when the machine body is turned during the plowing work.

[0004]

In a conventional four-wheel drive vehicle, when the machine body is turned during plowing work, the work machine is raised, one brake pedal is depressed, the front wheels are accelerated, and the steering is performed. The operations must be performed at the same time, and the operations are complicated. There is also known a four-wheel drive vehicle in which the steering angle of the steering wheel is detected to determine that the aircraft is in a turning state, and the speed-increasing operation of the front wheels and the rear wheel braking on the inside of the turning are automatically performed. When the lifting operation of the working machine is delayed, the rounded-up portion of the working machine remains largely inclined, which makes it difficult to finish the headland.

Therefore, there are technical problems to be solved in order to improve the turning performance of the four-wheel drive vehicle during the plowing work, simplify the turning operation, and prevent the field from becoming rough. The invention aims to solve this problem.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been proposed in order to achieve the above-mentioned object, and means for detecting the steering angle of the steering wheel, means for increasing the rotational speed of the front wheels during turning, and turning means. Sometimes means to brake the rear wheels inside the turn,
In a four-wheel drive vehicle equipped with a means for raising the work implement when turning, when the steering angle of the steering exceeds a set value, first, the means for raising the work implement is activated, and then another The present invention provides a turning control device in a four-wheel drive vehicle, which is provided with a control unit for activating the means.

[0007]

In the present invention, the steering angle of the steering wheel is always detected, and when the steering angle exceeds the set value, it is determined that the machine body is in the turning state. In that case, first, the means for raising the working machine is activated to automatically raise the working machine. After the working machine is raised to the highest position, the means for accelerating the rotation of the front wheels and the means for braking the rear wheels on the inside of the turn are activated to shorten the turning time of the machine body and reduce the turning radius.

[0008]

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of a control system in a tractor as an example of a four-wheel drive vehicle. The tilling depth adjustment dial provided on the input side of the control unit sets the tilling depth of the rotary, and the raising position adjustment dial is used. Set the highest position of the implement.
Then, the lift arm sensor detects the height of the working machine, and the rear cover sensor detects the depth of cultivation of the rotary.

Further, a steering angle sensor is provided as means for detecting the steering angle of the steering wheel, and an automatic brake switch for turning on / off the means for braking the rear wheel on the inside of the turn at the time of turning. Further, a check switch for shifting from the normal control mode to the check mode is provided, and the work machine is raised to the highest position or lowered to the position set by the position lever. Provide a lift switch.

On the other hand, a solenoid for raising the working machine and a solenoid for lowering the working machine are provided on the output side of the control unit. Further, a solenoid for the right brake and a solenoid for the left brake are provided as means for independently braking the rear wheel on the inside of the turn when the automatic brake switch is on, and the rotational speed of the front wheel is increased during the turn. A double speed device is provided as a means, and a double speed solenoid for turning on / off the double speed device is provided.

The left and right brake solenoids and the double speed solenoid are connected to switches which are opened and closed according to the detection value of a high speed sensor. When the machine is traveling at a high speed, the rear wheels on the inside of the turn are braked. The means for doing so and the means for increasing the rotational speed of the front wheels during turning do not operate. FIG. 2 is a flowchart of the entire control,
First, the detection value of each sensor is read (step 10
1) When both the check switch and the elevating switch are on, and immediately after the power is turned on (steps 102 → 103), the current sensor values are recorded in the EEPROM as respective reference values (steps). 10
4). In the check mode, the steering wheel is left in the neutral position (straight ahead) and recorded as the reference value of the steering angle sensor.

On the other hand, if either or both switches are off in step 102,
If it is not immediately after the power is turned on in step 3, sensor processing (step 105), position control or depth control (step 106), front wheel speed increase control (step 107), automatic brake control (step 108), automatic lift control (step). 109) and then step 10
Return to 1.

FIGS. 3 to 6 are flowcharts of the respective subroutines. First, in the position control or depth control routine, the lift arm target value is compared with the detection value of the lift arm sensor, and work is performed according to the deviation. Control is performed so that a rising signal is output to the machine lifting solenoid, a down signal is output to the working machine lowering solenoid, or a signal is not output when the deviation is in the dead zone. When the UP mode is set in the automatic lift control routine described later, the set value of the raising position adjustment dial is set to the lift arm target value,
Outputs a lift signal to the work equipment lift solenoid to raise the work implement to the highest position.

Next, the front wheel speed increasing control and the automatic brake control will be described. Both routines are executed only when the working machine lift flag is set to 1 in the automatic lift control routine described later. In the front wheel speed-up control, when the working machine lift flag is set to 1 and the detected value of the steering angle sensor is equal to or more than the set value, the double speed solenoid is turned on to operate the double speed device. Then, the rotational speed of the front wheels is increased to approximately twice that of the rear wheels.

On the other hand, in the automatic brake control, the working machine rising flag is set to 1 and the detected value of the steering angle sensor is equal to or more than the set value within a fixed time during counting of the working machine rising timer. When either of the two is reached, either the left or right brake solenoid is turned on and the rear wheel inside the turn is braked. When the work implement raising timer has finished counting, the solenoids for the left and right brakes are turned off, and the one-side braking of the rear wheels is not performed.

The automatic lift control will be described. First, when the automatic brake switch is on (step 201) and a signal is input from the rear cover sensor (step 202), the process proceeds to the next step. This is so that this control operates only during rotary work, and during other work such as fertilizer spraying, the swivel control including the automatic lift control does not operate.

Next, not immediately after the work implement raising operation (step 203) and after the work implement lowering timer has finished counting (step 204), the detected value of the steering angle sensor is changed from the straight traveling state. When it comes off (Step 2
05), the UP mode is set (step 206).
This is because the UP mode is not set immediately after the work machine is lifted and the set value of the raising position adjustment dial is not set to the lift arm target value in the position control described above, and the work machine is not raised to the maximum. To do.

Further, the work implement lowering timer is started immediately after the work implement lowering operation, which will be described later, is started (step 208).
209), when the working machine lowering timer does not finish counting, that is, the UP mode is not set within a certain time after the working machine is lowered and grounded, and an unfamiliar operator causes the machine body to meander after turning. Even if it does, the work implement should not rise again.

Then, in step 207, the work implement raising timer is started and the work implement raising flag is set to 1
Set to. Next, immediately after the work implement lowering operation is performed, the routine proceeds from step 208 to step 209, the work implement lowering timer is started, the work implement raising timer is cleared, and the work implement raising flag is reset to zero.
Even if it is not immediately after the work implement lowering operation, if the detection value of the steering angle sensor returns to the straight traveling state, the process returns from step 210 to step 209.

This is because when the working machine is descending or when the steering angle of the steering wheel is once returned to the straight traveling state, the working machine raising flag is reset to 0 and the front wheel speed increasing control and the automatic brake control are not operated. It was done like this. That is, when the turning is completed, the steering operation is performed while lowering the working machine, but the automatic brake control does not operate even if an unfamiliar operator operates the steering too much.

Thus, when the tractor during the rotary work controls the turning, the automatic raising of the working machine or the raising operation by the operator is given the highest priority, and then the front wheel speed increasing control and the automatic brake control are performed. It will be. Here, a steering angle sensor that detects the steering angle of the steering will be described. FIG. 7 shows the inside of the steering column 11. A screw portion 13 having a coarse pitch is provided at an intermediate portion of the steering shaft 12, and a boss 14 is screwed to the screw portion 13. A pin 15 is provided on the outer surface of the boss 14.
And a pin 15 is engaged with a slide groove 16 formed on the rear surface side (driver's seat side) of the steering column 11. Further, a steering angle sensor 17 is connected to the tip of the pin 15.

When the steering wheel 18 is steered to rotate the steering shaft 12, the boss 14 engaged with the screw portion 13 moves up and down, and the boss 1
The pin 15 projecting from 4 moves up and down in the slide groove 16. 8 and 9 show the steering angle sensor 17, in which a bracket 19 is fixedly provided near the slide groove 16 of the steering column 11, and the steering angle sensor 17 is fixed to the bracket 19 with a screw. The steering angle sensor 17 uses a rotary potentiometer, and is mounted so that the sensor shaft 20 projects toward the driver's seat. The detection arm 21 is attached to the sensor shaft 20.
One end is fixed, the locking groove 21a is opened at the other end of the detection arm 21, and the pin 15 protruding from the slide groove 16 is engaged with the locking groove 21a. Also,
The steering angle sensor 17 is arranged so that the steering column 11 and the detection arm 21 are orthogonal to each other when the steering wheel 18 is in the neutral position and the vehicle body is in a straight traveling state.
Set.

When the steering wheel 18 is steered to the left or right, the pin 15 moves up and down along the slide groove 16, the detection arm 21 rotates, and the detection value of the steering angle sensor 17 changes. . Based on the detection value of the steering angle sensor 17, the control unit calculates the steering angle of the steering wheel. At this time, the pin 15 moves up and down at an equal rate in proportion to the steering amount of the steering wheel 18, but even if the steering amount is the same, when the steering wheel 18 is close to the neutral position, the rotation angle of the detection arm 21. Is big.
That is, the resolution of the steering angle sensor 17 increases when the steering angle of the steering is in the vicinity of the neutral position, and minute changes in the steering angle can be detected finely.

In the present embodiment, a rotary potentiometer is used as the steering angle sensor 17, but the present invention is not limited to this. Although not shown, for example, a linear motion type potentiometer may be attached in the axial direction of the steering column 11. When that happens,
Since the sensor arm linearly moves in parallel with the steering column 11, the detector can be made compact.

Therefore, the present invention can be variously modified without departing from the spirit of the present invention, and it is obvious that the present invention covers the modifications.

[0026]

As described in detail in the above one embodiment, the present invention, in turning control of a four-wheel drive vehicle, first accelerates the working machine, then accelerates the front wheels and brakes the rear wheels inside the turning. Therefore, the work machine is dragged at the start of turning, or
The problem that the rounded-up part of the working machine remains largely inclined is solved.

As a result, the unevenness at the turning point is reduced,
The headland part can be finished easily, contributing to improved workability.

[Brief description of drawings]

FIG. 1 is a block diagram of a control system showing an embodiment of the present invention.

FIG. 2 is a flowchart of the entire control.

FIG. 3 is a flowchart of position control or depth control.

FIG. 4 is a flowchart of front wheel acceleration control.

FIG. 5 is a flowchart of automatic brake control.

FIG. 6 is a flowchart of automatic lift control.

FIG. 7 is a partially cutaway side view showing the inside of a steering column.

FIG. 8 is a rear view of a main portion of the steering column showing a mounting state of a steering angle sensor.

FIG. 9 is a side view of a main portion of a steering column showing a mounting state of a steering angle sensor.

[Explanation of symbols]

 11 Steering Column 12 Steering Shaft 14 Boss 15 Pin 17 Steering Angle Sensor

Claims (1)

[Claims] 1. A means for detecting a steering angle of a steering wheel, a means for increasing a rotational speed of a front wheel at the time of turning, a means for braking a rear wheel on the inside of the turning at the time of turning, and a means for raising a working machine at the time of turning. In a four-wheel drive vehicle equipped with a control unit, when the steering angle of the steering exceeds a set value, first, the means for raising the working machine is activated, and then the other means. A turning control device for a four-wheel drive vehicle, which is provided with: