JPH075017Y2 - Rear wheel steering device for automobiles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rear wheel steering device that can steer the rear wheels of a four-wheeled vehicle.

2. Description of the Related Art A technique is known in which the rear wheels can be steered according to the steering angle of the front wheels in order to improve the steering stability of the automobile at high speeds and the turning performance at low speeds. (See Japanese Laid-Open Patent Publication No. 62-88668).

This type of technology is configured such that hydraulic oil for power steering used to steer the front wheels is introduced into a cylinder for steering the rear wheels, and the rear wheels are steered in conjunction with the steering of the front wheels.

However, in such a conventional example, since the rear wheels are operated in conjunction with the front wheels, for example, when a parallel parked vehicle steers backwards from the vehicle body and escapes. In addition, there is a risk that the front part of the vehicle body may stick out and come into contact with another adjacent vehicle, making it difficult to escape.

Therefore, an object of the present invention is to provide a rear wheel steering device that can solve the above problems by independently steering only the rear wheels.

Means for Solving the Problems The present invention was devised in order to achieve the above-mentioned object, and the hydraulic oil supplied from the power steering pump to the power steering cylinder via the main pipe is used to steer the rear wheels. A main-rear wheel control valve that connects and disconnects this rear-wheel main conduit is installed in the middle of the rear-wheel main conduit that leads to the vehicle cylinder, and this main-rear wheel control valve is controlled by the controller according to the turning angle of the front wheels. Is a rear-wheel steering device for a vehicle in which the rear wheels are steered in conjunction with the turning of the front wheels by being controlled by the operation of the vehicle, and the rear-wheel steering device is selectively communicated with the main conduit via a first directional control valve. , A detour circuit that supplies hydraulic oil pumped from the power steering pump to the power steering cylinder via a relief valve, and between the main rear wheel control valve and the rear wheel steering cylinder by branching from this detour circuit. Rear wheel main Second in the pipeline
Attached to the controller and an independent rear wheel control circuit that supplies hydraulic oil that is selectively communicated through the direction switching valve and is pressure-fed through the bypass circuit to the rear wheel steering cylinder through the auxiliary rear wheel control valve. And a control switch unit for controlling the operation of the first directional control valve, the second directional control valve, and the auxiliary rear wheel control valve.

As a result of having the above-mentioned characteristic configuration, the present invention operates the first directional control valve, the second directional control valve, and the auxiliary rear wheel control valve by the control switch section, so that the hydraulic fluid pumped from the power steering pump is supplied. It is possible to pass through a bypass circuit provided with a relief valve. As a result, at least hydraulic oil having a pressure equivalent to the valve opening pressure of the relief valve is supplied to the power steering cylinder via the main pipe line and to the rear wheel steering cylinder via the independent rear wheel control circuit. . Therefore, the rear wheels are independently steered as necessary, although the rear wheels are normally steered in conjunction with the front steering.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a piping system diagram of a rear wheel steering system showing an embodiment of the present invention. According to this figure, the power steering pump 1 and the power steering cylinder 2 are connected to the main conduit 3.
The first directional control valve 4 is disposed in the middle of the main pipeline 3. In addition, a bypass circuit 6 that supplies the hydraulic oil that is selectively communicated with the main pipe line 3 by the first directional control valve 4 and is pressure-fed from the power steering pump 1 to the power steering cylinder 2 via the relief valve 5. Is attached. Reference numerals 7 and 8 denote rear wheel main pipelines connected to the main pipelines 3a and 3b. A main rear wheel control valve 9 and a second directional control valve 10 are sequentially arranged in the middle of the rear wheel main pipelines 7 and 8. The rear end is connected to the rear wheel steering cylinder 11. On the other hand, a single rear wheel control circuit 12 is arranged in parallel with the power steering cylinder 2 and the main rear wheel control valve 9. The independent rear wheel control circuit 12 is extended from the pipeline 14 branched from the pipeline 13 of the bypass circuit 6, the pipeline 16 extended from the reservoir tank 15, and the second directional control valve 10. A conduit 17,1
A secondary rear wheel control valve 19 that selectively connects and disconnects 8 and 8 is provided, and the second directional switching valve 10 connects and disconnects to the rear wheel steering cylinder 11. Reference numeral 20 denotes a controller. The controller 20 calculates detection signals from various sensors such as a steering angle sensor 21 and a vehicle speed sensor 22 and outputs a control signal to the main rear wheel control valve 9 in synchronization with the steering operation of the front wheels 23. Is output to control the operation of the main rear wheel control valve 9. As a result, the rear wheel main conduits 7a, 8
The a and the main conduits 8b, 7b for the rear wheels are connected / disconnected, and the rear wheels 24 are steered in conjunction with the steering of the front wheels. Further, the controller 20 includes a control switch unit 27 including a manual switch 25 for turning on the first directional switching valve 4 and the second directional switching valve 10 and a left / right operating switch 26 for operating the auxiliary rear wheel control valve 19.
Is attached.

FIG. 2 is a sectional view showing an example of the relief valve 5.
In this figure, the valve casing 28 has two oil chambers 2
9, 30 are formed, one oil chamber 29 is connected to the pipeline 13 of the bypass circuit 6 via the port 31, and the other oil chamber 30 is connected to the main pipeline 3 via the port 32. The valve hole 33 that connects the oil chamber 29 and the oil chamber 30 is closed by the valve body 34. The valve body 34 is pressed by a spring 35 which is set so that the valve opening pressure is a pressure sufficient to operate the rear wheel steering cylinder 11. Therefore, the relief valve 5 opens when the pressure in the bypass circuit 6 and the pressure in the oil chamber 29 become sufficient to operate the rear wheel steering cylinder 11,
Hydraulic oil having a pressure corresponding to the valve opening pressure is supplied to the power steering cylinder 2 side through the main pipe line 3. Therefore, even when the rear-wheel steering cylinder 11 is operated, the steering performance of the front wheels is not impaired. The port 36 is connected to the reservoir tank 15 via a conduit 37.

According to the structure of the above embodiment, when the manual switch 25 and the left and right operation switch 26 are in the OFF state (the state shown in FIG. 1)
The hydraulic oil pumped from the power steering pump 1 is supplied to the power steering cylinder 2 via the main pipe 3. Here, when the driver turns the steering wheel, the detection signal from the steering angle sensor 21 is input to the controller 20, and the main rear wheel control valve 9 is moved to the left and right in the figure based on the control signal output from the controller 20. And the rear wheel main pipes 7, 8 are opened. Therefore, the hydraulic oil supplied to the power steering cylinder 2 is also supplied to the rear wheel steering cylinder 11, and the rear wheel 24 is interlocked with the steering of the front wheel 23 and steered in the direction opposite to the steering direction of the front wheel. .

When the manual switch 25 is turned on, the first directional control valve 4 operates (moves to the right in the figure) to connect the bypass circuit 6 to the main pipeline 3, and the second directional control valve 10 operates (left in the figure). (Moving in the direction) to block the communication of the rear wheel main pipes 7 and 8 and connect the pipes 17 and 18 of the independent rear wheel control circuit 12 to the rear wheel steering cylinder 11. Then, when the left / right operation switch 26 is turned on together with the manual switch 25 being turned on, the sub rear wheel control valve 19 moves leftward or rightward in the figure, and the pipeline 14
And the conduit 16 and the conduit 17 and the conduit 18 are selectively communicated with each other.
At this time, the power steering pump 1 is installed in the bypass circuit 6.
Although the hydraulic oil pumped from is introduced, the relief valve 5 does not open unless the internal pressure of the bypass circuit 6 and the internal pressure of the oil chamber 29 (see FIG. 2) exceed a predetermined pressure. Therefore, at least the relief valve 5 is provided in the rear wheel steering cylinder 11 and the power steering cylinder 2.
The hydraulic oil having a pressure equivalent to the valve opening pressure is supplied.
As a result, the rear wheels 24 can be steered even when the vehicle runs at low speed on a snowy road where the discharge pressure of the power steering pump 1 is low and the road surface friction resistance is small. Even when the front wheels 23 are not steered, only the rear wheels 24 can be steered by operating the left / right operation switch 26 to operate the sub rear wheel control valve 19. Incidentally, since the hydraulic pressure similar to the hydraulic pressure applied to the rear wheel steering cylinder 11 also acts on the power steering cylinder 2 when the rear wheels 24 are steered, the steering operation of the front wheels 23 can be surely performed. .

FIG. 3 is a piping system diagram of a rear wheel steering system showing another embodiment of the present invention. In this embodiment, a displacement meter 38 is installed in the rear wheel steering cylinder 11, and a potentiometer 39 is installed in place of the left / right operation switch 26 installed in the controller 20.

According to this embodiment, when the manual switch 25 is turned on to steer the rear wheels 24, the set value of the potentiometer 39 set by the driver and the input signal input from the displacement meter 38 are input to the controller 20. Is calculated and compared by the controller
A control signal is output from 20 to the sub-rear wheel control valve 19, and the operation of the sub-rear wheel control valve 19 is controlled. As a result, the rear wheel 24 is connected to the potentiometer 39 set by the driver.
It is steered according to the set value of.

In each of the above embodiments, when the first directional control valve 4 and the second directional control valve 10 are de-energized to return to the original state (states of FIG. 1 and FIG. 3), The wheel control valve 9 connects the rear wheel main pipe 7b and the rear wheel main pipe 8b, and the restoring force of the spring 40 in the rear wheel steering cylinder 11 causes the rear wheel steering cylinder 11 to return to a neutral state. The rear wheels 24 return to the straight running state.

Effect of the Invention As described above, the present invention is provided with the control switch unit.
By operating the directional control valve, the second directional control valve, and the sub-rear wheel control valve, the hydraulic fluid pressure-fed from the power steering pump passes through the bypass circuit in which the relief valve is arranged,
Since the hydraulic oil of a predetermined pressure is configured to be supplied to the rear-wheel steering cylinder via the power steering cylinder and the bypass circuit via the bypass circuit and the independent rear-wheel control circuit, the rear wheels are Although the rear wheel steering device is steered in conjunction with the steering, only the rear wheels can be steered independently as necessary. As a result, during parallel parking, the rear portion of the vehicle body can be steered while moving backward to escape and the mobility of the vehicle can be significantly improved.

[Brief description of drawings]

FIG. 1 is a piping system diagram of a rear wheel steering apparatus showing an embodiment of the present invention, FIG. 2 is a sectional view of the relief valve, and FIG. 3 is a piping system diagram showing another embodiment of the present invention. . DESCRIPTION OF SYMBOLS 1 ... Pump for power steering, 2 ... Cylinder for power steering, 3,3a, 3b ... Main pipe line, 4 ... 1st directional control valve, 5 ... Relief valve, 6 ... Detour circuit, 7,7a, 7b, 8,8
a, 8b ... rear wheel main conduit, 9 ... main rear wheel control valve, 10 ... second directional control valve, 11 ... rear wheel steering cylinder, 12 ... independent rear wheel control circuit, 19 ... sub-rear wheel control valve, 20 ... Controller, 23 ... Front wheel,
24 ... rear wheel, 27 ... control switch section.

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. In the middle of a rear wheel main pipe for guiding hydraulic oil supplied from a power steering pump to a power steering cylinder via a main pipe to a rear wheel steering cylinder,
A main rear wheel control valve that connects and disconnects this rear wheel main pipe is installed, and the main rear wheel control valve is operated and controlled by the controller according to the turning angle of the front wheel, so that the rear wheel In a rear wheel steering system for an automobile that is steered in conjunction with steering, a relief valve is provided for operating oil that is selectively communicated with the main conduit via a first directional control valve and is pressure-fed from a power steering pump. A bypass circuit that supplies power to the power steering cylinder via the bypass circuit, and a branch from this bypass circuit that selects the rear wheel main pipe between the main rear wheel control valve and the rear wheel steering cylinder via the second directional control valve. Independent rear wheel control circuit that supplies hydraulic oil that is communicated with each other and is pressure-fed through the bypass circuit to the rear wheel steering cylinder through the sub-rear wheel control valve, and the first directional switching valve that is attached to the controller. , Second directional control valve and auxiliary rear wheel control Wheel steering system of a vehicle, characterized in that a control switch unit which controls the operation of the valve.