JP3613878B2 - 4-wheel steering tractor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a four-wheel steering tractor in which front and rear wheels can be steered, and more particularly to a steering control device in the same phase steering mode in which both front and rear wheels turn in the same direction.
[0002]
[Prior art]
FIG. 3 shows a hydraulic circuit of a steering device in a conventional four-wheel steering tractor. Reference numeral 1 is a steering cylinder for turning the front wheel 2, and reference numeral 3 is a steering cylinder for turning the rear wheel 4. The total hydraulic controller 6 is controlled by the rotation of the steering wheel 5, and the pressure oil of the hydraulic pump 7 driven by the engine (not shown) passes from the P port of the total hydraulic controller 6 through the A port or B port to the oil passage. To 8 or 9.
[0003]
In the four-wheel steering mode, the direction control valve 10 is switched to the position (B), pressure oil is supplied to the steering cylinder 1 and the front wheel 2 turns left or right, and the direction control valve 11 (B). Or it switches to the position (c), pressure oil is supplied to the steering cylinder 3, and the rear wheel 4 turns left or right. The pressure oil discharged from the steering cylinder 1 or 3 is returned to the tank 12 from the T port of the total hydraulic controller 6.
[0004]
Here, when the direction control valve 11 is switched to the position (B), the front and rear wheels 2 and 4 are in the same phase steering mode in which they are turned in the same direction, and the direction control valve 11 is set to the position (C). When switched, the front-wheel 2 and the rear-wheel 4 are in the reverse phase steering mode in which they are turned in opposite directions. Further, when switching from the four-wheel steering mode to the front wheel steering mode or the rear wheel steering mode, it is necessary to turn the front wheel 2 or the rear wheel 4 to the neutral state or a predetermined angle. One of the angle correcting solenoid valves 14 and 15 connected to the discharge oil passage 13 is switched, and the discharge oil of the hydraulic pump 7 is supplied to the steering cylinder 3 or the steering via the oil passages 16, 17 or 18, 19. Is supplied to the cylinder 1 and the turning angle of the front wheel 2 or the rear wheel 4 is forcibly corrected.
[0005]
[Problems to be solved by the invention]
When the four-wheel steering tractor travels along a contour line on a sloping ground, the airframe easily slides to the valley side. Therefore, as shown in FIG. 3, the directional control valves 10 and 11 are set to the same phase steering mode as shown in FIG. ), And the vehicle travels with the front wheels 2 and the rear wheels 4 slightly turned to the mountain side as indicated by the two-dot chain line. Since the working machine is connected to the rear part of the machine body, the rear wheel 4 may float up. At this time, the rear wheel 4 slides down to the valley side and the machine body does not return to the original posture.
[0006]
However, the conventional solenoid valves 14 and 15 for angle correction automatically operate when the steering mode is switched to correct the angles of the front and rear wheels 2 and 4, but the operator arbitrarily adjusts the turning angle. It is not possible.
[0007]
Therefore, the technical problem to be solved in order to allow the operator to arbitrarily adjust only the turning angle of the rear wheel and to prevent the skid when the four-wheel steering tractor travels on an inclined ground arises. It aims at solving this subject.
[0008]
[Means for Solving the Problems]
The present invention has been proposed to achieve the above-mentioned object, and controls the total hydraulic controller by rotating the steering wheel, and operates by arbitrarily selecting the front and rear wheel steering cylinders by switching the direction control valve. thereby enabling formation, a four-wheel steering tractor equipped with a solenoid valve for angle correction of the front wheels and the rear wheels communicating ports of the steering cylinder of the front and rear wheels to the tank, the same direction in the wheel both before and after In a four-wheel steering tractor provided with a manual switch capable of switching a solenoid valve for correcting the angle of the rear wheel during the same-phase steering mode turning to the rear wheel, the four-wheel steering tractor moves the manual switch to the rear wheel. An angle correction solenoid valve, a direction control valve, and a four-wheel steering controller for controlling the angle correction solenoid valve are provided in the middle of the wiring, and the manual switch is provided for the rear wheel angle correction solenoid. And an angle sensor that detects the turning angle of the front wheel is provided, and when the turning angle of the front wheel is less than a predetermined value by the detection of the angle sensor, the direction control valve is in phase. Even in the steering mode, the directional control valve is changed to the neutral position so that only the front wheels are steered, and when the turning angle of the front wheels exceeds the predetermined value, the directional control valve is turned on again. The present invention provides a four-wheel steering tractor configured to switch to the same phase steering mode and return to a state in which both front and rear wheels are steered .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a hydraulic circuit of a steering device for a four-wheel steering tractor. The same components as those of a conventional hydraulic circuit are denoted by the same reference numerals, and description thereof is omitted.
[0010]
The directional control valves 10 and 11 for the front and rear steering cylinders and the electromagnetic valves 14 and 15 for angle correction are controlled by command signals from the four-wheel steering controller 20. A manual switch 23 is provided in the middle of the wiring connecting the solenoids 21 and 22 and the four-wheel steering controller 20.
[0011]
The manual switch 23 is a normally open type, and when the operator manually operates the left side, the solenoid 21 is turned on, and when operated by the right side, the solenoid 22 is turned on. When the operator releases the hand, the manual switch 23 is returned to the neutral position, and both the solenoids 21 and 22 are turned off.
[0012]
Now, when the four-wheel steering tractor travels along a contour line on an inclined ground, the airframe easily slides to the valley side, so that the direction control valves 10 and 11 are set to the same phase steering mode as shown in FIG. The vehicle is switched to the position (b) and travels with the front wheels 2 and the rear wheels 4 slightly turned to the mountain side as indicated by the two-dot chain line. However, since the work machine is connected to the rear part of the machine body, the rear wheel 4 may be lifted, and the slip of the rear wheel 4 toward the valley side is increased.
[0013]
At that time, if the operator operates the manual switch 23 to the mountain side (left side in the figure), the solenoid 21 is turned on and the solenoid valve 14 is switched to the position (B). Accordingly, the oil discharged from the hydraulic pump 7 is supplied to the steering cylinder 3 via the oil passage 16, and the rear wheel 4 is further turned to the mountain side to prevent the rear wheel 4 from slipping to the valley side.
[0014]
When the correction of the turning angle of the rear wheel 4 is completed, if the operator releases the hand from the manual switch 23, the manual switch 23 returns to the neutral position, the solenoid 21 is turned off, and the solenoid valve 14 is turned off. The vehicle returns to the position (a) and travels in the original in-phase steering mode.
[0015]
Here, when traveling on an inclined ground in the same phase steering mode, when the field has a gentle inclination angle and the turning angles of the front and rear wheels 2 and 4 are small, the rear wheel 4 is moved as it is in the same phase steering mode. There is a problem that the mountain starts to climb up.
[0016]
In order to prevent this, an angle sensor (not shown) for detecting the turning angle of the front wheel 2 is provided, and when the turning angle of the front wheel 2 is less than a predetermined value (for example, 5 degrees) by the detection of the angle sensor. Even in the in-phase steering mode, the direction control valve 11 is forcibly switched to the neutral position (A) and changed so that only the front wheels 2 are steered. Then, when the turning angle of the front wheel 2 becomes a predetermined value or more, the direction control valve 11 is switched again to the position (B), and both the front wheel 2 and the rear wheel 4 are automatically steered. Return.
[0017]
Further, instead of the manual switch 23, a sensor for detecting inclination may be provided. FIG. 2 shows an interstitial work machine 30. Arms 32 and 33 are attached to the left and right positions of a rotary cover 31 so as to be swingable up and down, and rollers 34 and 35 are pivotally attached to the arms 32 and 33, respectively. In addition, the heel sensors 36 and 37 are mounted inside the arms 32 and 33 so that the upward rotation of the arms 32 and 33 can be detected.
[0018]
Now, when the inclination angle of a farm field changes on the way while the furrow working machine 30 is traveling, the furrow working machine 30 is inclined toward a lower gradient. At this time, the roller located on the valley side of the left and right rollers 34 and 35 abuts against the flange 38 or 39, the roller is pressed, the arm 32 or 33 is rotated upward, and the flange sensor 36 or 37 is Turned on and the inclination of the furrow working machine 30 is detected.
[0019]
For example, in the figure, when the furrow working machine 30 is tilted to the left side, the saddle sensor 36 is turned on, and the electromagnetic valve 14 is moved to the position (C) in order to correct the turning angle of the rear wheel 4 to the right side. Switch. Further, when the furrow working machine 30 is tilted to the right side, the saddle sensor 37 is turned on, and the electromagnetic valve 14 is switched to the position (B) in order to correct the turning angle of the rear wheel 4 to the left side.
[0020]
In this way, even when the left and right inclination angles change every moment in a wavy field, the turning angle of the rear wheel 4 is automatically corrected by the detection of the heel sensors 36 and 37, and the skidding of the rear wheel 4 Can be prevented.
[0021]
It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.
[0022]
【The invention's effect】
As described above, according to the present invention, the operator can operate the manual switch to adjust the turning angle of the rear wheel. Therefore, for example, when a four-wheel steering tractor travels along a contour line on an inclined surface, by adjusting only the turning angle of the rear wheel as needed, a side slip on an inclined land can be prevented and the traveling stability can be improved. .
Furthermore, the present invention provides an angle sensor for detecting the turning angle of the front wheel, and when the turning angle of the front wheel is less than a predetermined value by the detection of the angle sensor, the direction control valve is in the in-phase steering mode. However, when the directional control valve is changed to the neutral position and only the front wheels are steered, and the turning angle of the front wheels exceeds the predetermined value, the directional control valve is again set to the same phase steering mode. Since it is configured so that both the front and rear wheels are switched to return to a state where the front and rear wheels are steered, when traveling on an inclined land in the same phase steering mode, the field inclination angle is gentle and the front and rear wheel turning angles are small. Thus, it is possible to avoid the problem that the rear wheel starts to climb to the mountain side when traveling in the same phase steering mode as it is, and the stability of traveling can be further secured.
[Brief description of the drawings]
FIG. 1 is a hydraulic circuit diagram of a steering device according to an embodiment of the present invention.
FIG. 2 is a rear view of a furrow working machine according to another embodiment.
FIG. 3 is a hydraulic circuit diagram showing a conventional technique.
[Explanation of symbols]
1, 3 Steering cylinder 2 Front wheel 4 Rear wheel 5 Steering wheel 6 Full hydraulic controller 10, 11 Direction control valve 12 Tank 14, 15 Solenoid valve 20 (for angle correction) Four-wheel steering controller 23 Manual switch

Claims (1)

Controls all hydraulic controller by the rotation of the steering wheel, and forming operably arbitrarily selecting a steering cylinder of the front wheel and the rear wheel by switching the directional control valve, each of the steering cylinders of the front wheels and rear wheels a four-wheel steering tractor equipped with a solenoid valve for angle correction of the front wheels and the rear wheels communicating the port to the tank, in the same phase steering mode to EKO in the same direction wheels both front and rear, for angle correction of the rear wheel In a four-wheel steering tractor with a manual switch that can switch the solenoid valve of
In the four-wheel steering tractor, the manual switch is provided in the middle of the wiring connecting the electromagnetic valve for correcting the angle of the rear wheel and the four-wheel steering controller for controlling the direction control valve and the electromagnetic valve for angle correction. When only the rear-wheel angle correction solenoid valve is configured to be switchable, and an angle sensor for detecting the turning angle of the front wheel is provided, and the turning angle of the front wheel is less than a predetermined value by the detection of the angle sensor. Is changed so that only the front wheel is steered by switching the directional control valve to the neutral position even when the directional control valve is in the in-phase steering mode, and the turning angle of the front wheel becomes equal to or greater than the predetermined value. In this case, the four-wheel steering tractor is configured so that the direction control valve is again switched to the in-phase steering mode to return to a state where both the front and rear wheels are steered.

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