JP3577762B2 - Four-wheel steering system for mobile agricultural machines - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a steering start safety device for a four-wheel steering vehicle. The present invention relates to a vehicle in which independent steering mechanisms are provided on the front and rear sides of an airframe, and the steering mechanisms are independently or interlocked, and the combination of the steering mechanisms is changed to improve small-turnability and steer.
[0002]
2. Related Art and Problems to be Solved by the Invention
Vehicles that steer while changing the combination of conventional four-wheel steering in various ways have a special body that pursues small turning performance when starting the engine and starting steering after storing in a parking place for a long time. It was easy for the driver to steer in a direction that the driver did not even think that he did not know that he was moving or misunderstood because he was in a hurry.
[0003]
Therefore, there is a type in which the current steering mode is notified by lighting or blinking of a lamp or a buzzer sound. However, even in such a solution, there is a drawback that the function cannot be exhibited if the driver does not know the meaning of the switching mode too much or ignores it, because there are too many switching modes.
[0004]
[Means for Solving the Problems]
The present invention is to solve such a problem of the conventional device, and has taken the following technical measures. That is, it has a front wheel steering mode, a rear wheel steering mode, and a front and rear wheel steering mode, and selects a steering mode by switching a steering mode switch. In the mobile agricultural machine configured to be in the front wheel steering mode, the mode holding means for restraining the shift to the front wheel steering mode when the engine is restarted for a short time immediately after the engine is stopped is provided. The feature is a four-wheel steering device for a mobile agricultural machine .
[0005]
【Example】
The illustrated example is an agricultural tractor 6 in which the present invention is folded into a steering device. Front and rear wheels 8, 7 are provided on the front and rear of the agricultural tractor 6 as shown in the side view of FIG. 3, and a double-acting type is shown in the hydraulic circuit diagram of FIG. Front and rear hydraulic cylinders 9 and 10 are attached.
[0006]
An engine 4 is disposed above the front wheels 7 and 7, and an upper portion and sideways are covered with a hood 11. A seat 12 is provided above the rear wheels 8, 8, and a handle 13 is located at a rear portion of the hood 11 in front of the driver when the driver sits down. Reference numeral 14 denotes a floor on which a driver places his / her feet. An instrument panel 14 is provided below the handle 13 at the rear of the bonnet 11, and a steering mode switch 3, which will be described later, is arranged.
[0007]
The handle 13 is interlocked with the all-hydraulic steering device 15 via a handle shaft 16. By turning the metering pump 17 at the lower end in the left or right direction, the left turning oil passage 18 or the right turning This determines which of the recirculation passages 19 the oil flows first. At this time, when the hydraulic pump 20 driven by the engine 4 operates and the pressure oil reaches the high-pressure oil circuit 21, the metering pump 17 acts as a directional switching valve and uses the high-pressure oil to lighten. When the engine 4 is turning quickly and the engine 4 is stopped, the metering pump 17 functions as a manual hydraulic pump to operate the front wheels 7, 7 and the rear wheels 8, 8, and the operation will be described later. Steer independently or in conjunction with each other.
[0008]
Next, the operation of the steering will be described. In the case of a left turn, the pressure oil flowing to the left turn oil passage 18 by the metering pump 17 by moving the handle 13 to the left passes through the neutral chamber 22a of the rear wheel oil passage switching valve 22 as shown in FIG. It reaches the road switching valve 23. Then, pressure oil flows into the left turning chamber 9a of the front hydraulic cylinder 9 through the working chamber 23b of the front wheel oil passage switching valve 23, and moves the front bell crank 24 in the direction of arrow "a" to move the front wheels 7, 7 to the left. Steer toward and drive. In the case of right turning, in the opposite direction, the pressure oil that has flowed to the right turning oil passage 19 by the metering pump 17 passes through the working chamber 23 b of the front wheel oil passage switching valve 23 and the right turning chamber of the front hydraulic cylinder 9. The pressure oil flows into 9b and the front wheels 7, 7 are steered to the right. The oil in the left turning chamber 9a reaches the metering pump 17 from the working chamber 23b of the front wheel oil passage switching valve 23 through the neutral room 22a of the rear wheel oil passage switching valve 22, and is discharged from the low pressure circuit 25 to the oil tank 26. . A front potentiometer 27 is provided at the center of the swing of the front bell crank 24. The front potentiometer 27 detects the expansion / contraction movement of the front hydraulic cylinder 9 or the steering angle of the front wheels 7, 7, and transmits the result to a CPU 28 which is a microcomputer described later. Used for various controls. This steering action is an explanation of the movement when the steering mode switch 3 provided in the vicinity of the instrument panel 14 is set to the front wheel steering mode 5, and the front part of the body is steered in the same manner as a normal road running automobile or the like. It turns while moving laterally in the direction, so that ordinary people can steer without discomfort.
[0009]
The rear wheel oil passage switching valve 22 and the front wheel oil passage switching valve 23 are electromagnetic solenoid valves, and are automatically switched to the neutral chambers 22a, 23a or the working chambers 22b, 23b by the CPU 28 as shown in the electric circuit diagram of FIG. Is done. That is, when the steering mode switch 3 is set to the rear wheel steering mode 29, the rear wheel oil passage switching valve 22 in FIG. 2 is switched to the working chamber 22b, and the front wheel oil passage switching valve 23 is switched to the neutral room 23a.
[0010]
In the case of the rear wheel steering mode 29, the pressure oil in the high pressure oil circuit 21 shown in FIG. Only the vehicle 10 is operated by telescopic steering. This steering operation is a special steering operation. When the steering wheel 13 is operated in the left-right direction, the rear part of the body turns while moving in the left-right direction, and is usually used for steering of a forklift or the like. Although it is convenient to accurately position the front of the aircraft, when looking only at the front during driving, the rear of the aircraft may be in danger of hitting other objects on the side and requires skill to control.
[0011]
Further, when the steering mode switch 3 is set to the four-wheel steering mode 30, the rear wheel oil passage switching valve 22 and the front wheel oil passage switching valve 23 are both operated chambers 22b and 23b, and the front hydraulic cylinder 9 and the rear hydraulic cylinder 10 are simultaneously operated. Is done. The traveling by this movement is to steer along a certain circumference, and when turning on soft soil, the front and rear wheels 7, 8 coincide with the traveling direction, so that the soil surface is not damaged. You can steer lightly.
[0012]
When the driver switches the steering mode to the front wheel steering mode 5, the rear wheel steering mode 29, or the four-wheel steering mode 30, the steering mode is displayed on the steering mode display 33 near the instrument panel 14 in accordance with the switching. It is displayed and distinguished by a lamp or the like. As described above, the agricultural tractor 6 can adjust the steering and turning of the wheels in various ways according to the purpose of the work. Then, it can be understood by looking at the steering mode display 33.
[0013]
Next, the main part of the present invention will be described. When the hydraulic pump 20 is driven after the start of the engine 4, the internal pressure of the high-pressure oil circuit 21 increases. The internal pressure is detected by a hydraulic gauge 32 or the engine tachometer 31 detects that the engine 4 is being driven. . When the detection that the engine 4 is being driven is transmitted to the CPU 28, the present invention can be applied to any state of the steering mode switch 3 among the front wheel steering mode 5, the rear wheel steering mode 29, and the four-wheel steering mode 30. In the front wheel steering mode 5, the rear wheel oil passage switching valve 22 and the front wheel oil passage switching valve 23, which are electromagnetic solenoids, are switched, and the steering mode display 33 displays the front wheel steering mode 5 and the forcible change. As a result, even if the rear hydraulic cylinder 10 moves the handle 13, the rear hydraulic cylinder 10 does not extend and retract, and if the previous operation is in a steering state where the vehicle is not traveling straight, there is a possibility that the rear part of the body may move obliquely. Therefore, control by the rear wheel straight-running control valve 34 provided in the middle of the high-pressure oil circuit 21 will be described.
[0014]
The rear wheel straight-running control valve 34 is an electromagnetic solenoid type three-chamber switching valve, and is operated via the CPU 28 by detecting a steering angle of a rear bell crank 35 for steering the rear wheels 8 and a rear potentiometer 36. That is, the left or right steering angle of the rear wheels 8, 8 is detected by the rear potentiometer 36. For example, pressure oil enters the left turning chamber 10a of the rear hydraulic cylinder 10, and the rear wheels 8, 8 are turned right. If so, pressurized oil that has passed through the right chamber 34b of the rear wheel straight-ahead control valve 34 is supplied to the right turning chamber 10b on the opposite side, and is automatically controlled by the CPU 28 until the rear potentiometer 36 detects the straight-ahead state. The pressure oil via the left chamber 34a is connected to the left turning chamber 10a of the rear hydraulic cylinder 10, and corrects when the rear wheels 8, 8 are turned to the left.
[0015]
In this manner, the rear wheels 8, 8 are automatically corrected in the straight traveling direction at the time of starting, and the steering is performed by steering the front wheels. When the steering of only the rear main wheels 8 and 8 and the simultaneous steering of the front and rear wheels 7 and 8 are required according to the type of work, the driver may manually change the steering mode switch 3. Further, the operation of the engine 4 is detected by the engine tachometer 31 and the oil pressure gauge 32. For a short period of time, for example, about 1 minute to 2 minutes after the engine 4 is stopped, the mode holding for automatically changing the steering mode is maintained. Ru worked the mechanism 37.
[0016]
This is to restart the engine when the engine is stopped due to an overload unintended by the driver during the operation. At that time, the operation can be continued without changing the steering mode. As a modified example of the gist configuration, when the stop operation of the engine 4 is detected by the stop operation detector 38, the engine 4 is not immediately stopped, but the steering direction of the rear wheels 8, 8 is detected by the rear potentiometer 36, and the rear wheels go straight. If the rear hydraulic cylinder 10 is controlled to the straight running state by the control valve 34 and then stopped, since the rear wheels 8, 8 are already in the straight running state at the next start of the engine 4, the operation can be similarly safely started. The effect that can be produced.
[0017]
Operation and Effect of the Invention
The present invention has the following technical effects by the above configuration. That is, even if the steering mode at the end of the work is a mode other than the front wheel steering mode, when the engine is started, the rear wheels are in a straight-ahead state and the front wheel steering mode in which only the front wheels can be steered. It can be operated as if it were a car, and there is no embarrassment or panic.
In addition, when the engine was overloaded during the operation and the engine stopped, the transition to the front wheel steering mode was stopped for a short time immediately after the engine was stopped even if the engine was restarted. The steering mode selected at that time can be used as it is, and it is possible to eliminate a problem that the efficiency of the work is reduced by shifting to the front wheel steering mode when the engine is started .
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of control.
FIG. 2 is an explanatory diagram of a hydraulic circuit.
FIG. 3 is an overall side view of the mobile vehicle.
[Explanation of symbols]
Reference Signs List 1 front wheel steering mechanism 2 rear wheel steering mechanism 3 steering mode switch 4 engine 5 front wheel steering mode

Claims (1)

It has a front wheel steering mode, a rear wheel steering mode, and a front and rear wheel steering mode, and selects one of the steering modes by switching a steering mode switch. When the engine is started, regardless of the mode setting by the steering mode switch, the front wheel In the mobile agricultural machine configured to be in the steering mode, a mode holding unit that restrains the transition to the front wheel steering mode when the engine is restarted for a short time immediately after the engine is stopped is provided. Four-wheel steering system for mobile agricultural machinery .

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