JPH03217375A - Steering device for four-wheel steering vehicle - Google Patents

Abstract

PURPOSE:To detect an abnormal steering interlocked state in an early stage by installing an annunciator which informs an operator of it when a difference in the absolute value of a steering angle by each steering angle sensor for both front and rear wheels is more than the specified value, in a four-wheel steering vehicle equipped with both front and rear wheels being steered by a steering hydraulic device. CONSTITUTION:A steering device for a tractor steers both front and rear wheels 3, 4 by means of steering rotation of a steering wheel 1 when each of steering arms 18, 19 is turned round steering arm pins 20, 21 by a steering hydraulic device 2 through a hydraulic type power steering 17. This steering hydraulic device 2 is provided with each of steering control valves 27, 28 and steering cylinders 29, 30 for rotating these steering arms 18, 19, and the steering control valves 27, 28 are controlled by a controller according to the operating state. In this case, there are provided with respective front-rear-wheel steering angle sensors 5, 6 detecting each steering angle of both front and rear wheels 3, 4. When a difference in the absolute value of a steering angle by both sensors 5, 6 is more than the specified value, an annunciator is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a steering device for a four-wheel steering vehicle such as a passenger tractor.

(Prior Art and Problems to be Solved by the Invention) In a four-wheel-throttle vehicle that steers both the front wheels and the rear wheels, leakage or malfunction of the valve in the steering hydraulic system may cause the front wheels to A large difference in steering angle with the rear wheels may occur, and in such cases it is necessary to quickly detect and deal with the situation.

(Means for Solving the Problems) This invention provides a steering angle θ between a front wheel 3 and a rear wheel 4 that are steered by a steering wheel 1 via a steering hydraulic system 2.
,, θ2 are provided, and a front wheel steering angle sensor 5 and a rear wheel steering angle sensor 6 are provided, and a notification is provided when the difference θ between the absolute values of the steering angles θ1 and θ2 detected by both the steering angle sensors 5 and 6 is equal to or greater than a predetermined value. This is the configuration of a steering device for a four-wheeled vehicle, which is provided with a steering wheel 7.

(Function) By steering the steering wheel 1, the front wheels 3 and the rear wheels 4 are steered by the steering hydraulic system 2, and the running direction is changed. At this time, the steering angle θ1 of the front wheels 3 is detected by the front wheel steering angle sensor 5, and the steering angle θ2 of the rear wheels 4 is detected by the rear wheel steering angle sensor 6.
When the difference θ between the absolute values of these steering angles Ol and θ2 exceeds a predetermined value, the annunciator 7 notifies this.

(Effect of the invention) In this way, the steering angle θ of the front wheels 3 and the steering angle θ2 of the rear wheels 4 of the four-wheel steering vehicle are detected by the front wheel steering angle sensor 5 and the rear wheel steering angle sensor 6, Based on the difference θ between these steering angles, the alarm 7 notifies whether the interlocking state of the steering hydraulic system 2 is normal or abnormal, so that an abnormal steering interlocking state can be accurately and quickly known. .

(Example) The illustrated example shows a case where it is used as a steering device for a tractor, and the front part of the vehicle body 8 includes a steering wheel 1,
An engine 9 is provided, and a hydraulic lift cylinder 12 and the like for raising and lowering a lift arm 11 connecting a cockpit 10 and a working device are provided at the rear. The front wheels 3 and the rear wheels 4 are driven in a four-wheel drive mode in which the engine 9 transmits power through a transmission in a transmission case 13.
The fuel is then sent to the steering hydraulic circuit 15 of the steering hydraulic system 2 and the lifting hydraulic circuit 16 of the lift cylinder 12.

The front wheels 3 and the rear wheels 4 are operated by hydraulic power steering (power steering) by steering rotation of the steering wheel 1.
The steering arms 18 and 19 are rotated around the steering arm bins 20 and 21 by the steering hydraulic device 2 by the bit roll) 17, and the rods 23 and 24 are rotated from the steering arms 18 and 19 to the steering arm bins 20 and 21.
The knuckle arm 25 of the front wheel 3 and the rear wheel 4 via
The knuckle arm 26 is configured to be steered and rotated. The steering hydraulic circuit 15 of the steering hydraulic system 2 includes steering control valves 27 and 28 for rotating the respective steering arms 18 and 19.
, and steering cylinders 29, 30 are provided, and the steering cylinders 29, 30 are controlled by switching control of the steering control valves 27, 28.
The structure is such that the front wheels 3 and rear wheels 4 are steered by telescopically operating the front wheels 3 and rear wheels 4.

Further, the steering control valve 28 for the rear wheels 4 is set to the forward and reverse steering positions A.
．． C, there is a switching boat with a neutral position B, and the steering control valve 27 of the front wheel 3 has a switching port with a steering position D and a neutral position E, and both steering control valves 27 and 28 are operated by a circuit 31. The steering cylinder 29 of the front wheels 3 is operated by the hydraulic pressure discharged from the steering cylinder 30 of the rear wheels 4.

In addition, these steering control valves 27 and 28 are used to select the mode of steering mode using the mote changeover switch 33 of the steering device, and as shown in FIGS. 2 to 5, the front wheel steering mode is ( (Fig. 2), by selecting and switching the steering control valve 27 to the steering position D and the steering control valve 28 to the neutral position B, only the front vehicle 3 is steered, and the rear wheels 4 are driven straight. Fixed in state. In the rear wheel steering mode (FIG. 3), the steering control valve 27 is set to the neutral position E, the steering control valve 28 is set to the steering position C, and only the rear wheels are steered. In the in-phase mode (FIG. 4), the steering control valves 27 and 28 are moved to the steering position D. As A, the front vehicle 3 and the rear vehicle 4 are steered in the same direction. or,
In the reverse phase mode (Fig. 5), the steering control valves 27 and 28
are set as steering positions D and C, and the front wheels 3 and rear wheels 4 are steered in opposite directions.

The lift hydraulic circuit 16 is provided with a lift control valve 32 to control expansion and contraction of the lift cylinder 12.

The steering angle θ1 of the front wheels 3 is determined by detecting the rotation angle of the steering arm 18 around the steering arm bin 20, and a front wheel steering angle sensor 5 is provided. Similarly, the steering angle θ2 of the rear wheels 4 is detected by a rear wheel steering angle sensor 6 provided in the steering arm bin 21 section.

These steering angle sensors 5 and 6 and the mote switching switch 3
3, the alarm 7 such as an abnormality alarm lamp or a buzzer, and the steering control valves 27 and 28 are configured to be operated in conjunction with solenoids by a controller having a microcomputer CPU. The selection control by mode switching of the steering control valves 27 and 28 is as described above (shown in FIGS. 2 to 5), but the alarm 7 is controlled as shown in FIG.
The difference θ between the absolute values of the front wheel steering angle θ1 and the rear wheel steering angle θ2 is
An output notification is issued when the angle is calculated as being larger than an angle set as a tolerance (for example, 2 degrees).

[Brief explanation of drawings]

The figures show one embodiment of the present invention, in which Fig. 1 is a hydraulic circuit diagram, Figs. 2 to 5 are plan view mechanical diagrams of the tractor showing operation modes, Fig. 6 is a control block diagram, and Fig. 7 is a control block diagram. Flowchart, FIG. 8 is a partial plan view of the tractor, and FIG. 9 is a side view thereof. (Explanation of symbols) 1 Steering wheel 2 Steering hydraulic system 3 Front wheels 4 Rear wheels 5 Front steering angle sensor 6 Rear wheel steering angle sensor 7 Alarm

Claims (1)

[Claims] Steering angles θ_1, θ_2 between the front wheels 3 and rear wheels 4 that are steered by the steering wheel 1 via the steering hydraulic system 2
A front wheel steering angle sensor 5 and a rear wheel steering angle sensor 6 are provided to detect the steering angle θ_
1. A steering device for a four-wheeled vehicle, which is provided with an alarm 7 that notifies when the difference θ between the absolute values of θ_2 is greater than or equal to a predetermined value.