JPH0331067A - Response delay absorbing device for hydraulic actuator - Google Patents

Abstract

PURPOSE:To absorb a response delay in a hydraulic actuator by connecting either a valve box or a valve unit, which constitutes a direction selector valve for controlling the rear wheel steering hydraulic actuator, to an input displacement transmitting member and the other to an action member of the hydraulic actuator through a spring. CONSTITUTION:A rear wheel steering mechanism has a direction selector valve A comprising a valve box 6 and a valve unit 12 slidably fitted to this valve box 6. An annular groove 8, formed in the center of the internal peripheral surface of this valve box 6, communicates with the delivery port of an oil hydraulic pump 4, and grooves 9, 7 in both sides communicate with an oil tank 3. A port, respectively provided between the grooves 8, 9 and between the grooves 8, 7, communicates with a pair of end chambers 32, 33 of a hydraulic actuator C. Here a response delay absorbing device B is provided in the end part of the valve unit 12 and connected to a tie rod of the hydraulic actuator C through a remote cable 18. The response delay absorbing device B is constituted by fitting a spring 16 between a rod 12a on the end part of the valve unit 12 and a cylinder 17, fitted to this rod 12a, and one end of the remote cable 18 is fixed to the cylinder 17.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is directed to a III control and device for controlling a hydraulic actuator for rear wheel steering in a four-wheel steering vehicle, particularly for absorbing a delay in the response of the rear wheels to a steering wheel operation. The present invention relates to a response delay absorbing device for a hydraulic actuator.

[Prior Art] The present applicant has disclosed in Japanese Patent Application No. 63-240361 that a hydraulic actuator for steering the rear wheels is used as a rear wheel steering mechanism in a four-wheel steering vehicle in conjunction with steering wheel operation, and a valve box and a valve body are connected to each other. When one is driven, a hydraulic circuit is formed, and the hydraulic actuator is actuated to steer the rear wheels. At the same time, the operation of the hydraulic actuator is transmitted to the other of the valve body and valve body of the directional valve via a remote cable, and the hydraulic circuit is activated. We are currently applying for a system that allows the robot to return to its neutral position.

According to the above-mentioned rear wheel steering mechanism, the directional control valve and the hydraulic actuator are simply connected by a conduit and a remote cable for feedback, so the directional control valve and the hydraulic unit can be disposed near the engine or the steering wheel. It is possible to do this by simply installing a hydraulic actuator in the rear wheel suspension.
The overall arrangement is reasonable.

However, in the above-mentioned rear wheel steering mechanism, if a delay in the response of the rear wheels to a steering wheel operation occurs, an unreasonable force acts on the transmission mechanism. If the response delay is within the allowable range, the only load acting on the input displacement transmitting member linked to the handle and the response displacement transmitting member linked to the hydraulic actuator is the deflection load of the neutral return spring, but if the response delay exceeds the allowable range. and,
The displacement is forced to be transmitted, and not only is an excessive load applied to both transmission members, but also an overload is applied to the signal source.

That is, when the handle is turned rapidly and greatly, the directional control valve exceeds the limit of relative movement between the valve body and the valve body, and the above-mentioned situation occurs when the valve body is forcibly driven by the valve body.

Therefore, in order to avoid such a situation, it is possible to increase the amount by which the valve body and the valve body can move relative to each other, but this is not preferable because the directional control valve becomes long. This situation is not limited to spool-type directional valves, but also applies to rotary-type directional valves. It becomes necessary to arrange a valve groove on the circumferential surface of the diameter, and the directional control valve has a large diameter.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, the object of the present invention is to provide a system that absorbs the response delay of the output operation section with respect to the input operation to the directional control valve that accompanies an operation such as turning the steering wheel rapidly and greatly. An object of the present invention is to provide a response delay absorbing device for a hydraulic actuator that can achieve smooth rear wheel steering.

[Means for Solving the Problems] In order to achieve the above object, the present invention has a structure in which a directional control valve for driving a hydraulic actuator υ1110 is composed of a valve body and a valve body fitted into the valve body, and the valve body and the valve body are connected to each other. One of the valve bodies is connected to an input displacement transmission member, and the other is connected to an operating member of a hydraulic actuator via a spring that expands and contracts within a predetermined range.

[Operation] When the handle is operated greatly and quickly, the valve body (valve body or valve body) moves relative to the valve body against the force of the neutral return spring, forming a hydraulic circuit to the hydraulic actuator. At this time, if the valve body exceeds the allowable relative movement amount, the valve body will be dragged by the valve body, but the spring interposed between the valve body and the remote feedback cable connected to the operating part of the hydraulic actuator will No bending or excessive force is applied to the remote cable.

The spring absorbs the response delay of the hydraulic actuator and helps the handle operate smoothly.

[Embodiments of the Invention] FIG. 1 is a plan view showing a rear wheel steering mechanism in a four-wheel steering vehicle equipped with a hydraulic actuator response delay absorbing device according to the present invention. The rear wheel steering mechanism includes a directional control valve A, a response delay absorbing device B, and a hydraulic actuator C. The directional control valve A consists of a valve body 6 and a valve body 12 slidably fitted into the valve body 6, both of which are biased to the illustrated neutral position by a neutral return spring 10. That is, a cylindrical portion 11 is provided on the valve body 6 and the valve body 12 so as to straddle the fitting circumferential surface of the valve body 6 and the valve body 12, and a cylindrical portion 11 is provided between the pair of spring seats engaged with both ends of the cylindrical portion 11. A return spring 10 is interposed.

Preferably, three cylindrical parts 11 are arranged at equal intervals in the circumferential direction of the valve body 12. An annular groove 8 is cut in the center of the inner circumferential surface of the valve box 6, and annular grooves 9.7 are cut on both sides, and the center groove 8 communicates with the discharge port of the hydraulic pump 4 through 1!27. . The grooves 9.7 on both sides communicate with the oil tank 3 via a pipe 28. The boat provided between the grooves 8 and 9 communicates with one end chamber 32 of the hydraulic actuator C via a pipe 20. Similarly, a boat provided between grooves 8 and 7 of the valve body 6 communicates with the other end chamber 33 of the hydraulic actuator C via a pipe 19.

On the other hand, a pair of annular grooves 13 and 14 are provided in the valve body 12, and in the neutral position, the groove 13 communicates with the grooves 8 and 9;
4 connects groove 8 and groove 7. The valve box 6 is connected to the steering shaft 2 via the connecting member 5, and is allowed to slide left and right as the steering shaft 2 rotates.

This connecting member 5 is actually provided with a dead zone that prevents the valve box 6 from sliding from the neutral position of the handle to a predetermined turning angle, but since this is not directly related to the present invention, a description thereof will be omitted.

The valve body 12 is connected to the tie rod 2 of the hydraulic actuator C via the response delay absorbing device B according to the present invention and a remote cable 18.
Connected with 6. Hydraulic actuator C is cylinder 25
A piston 21 is fitted in the piston 21, and a tie rod 26 connected to the piston 21 protrudes from both end chambers. The left end of the tie rod 26 is attached to the knuckle arm 24, which supports the left rear wheel 22 of the vehicle, by a pin 29. The knuckle arm 24 is rotatably supported by the vehicle body by a vertical support shaft 23. Although the right end side of the tie rod 26 is not shown, it is connected to a knuckle arm that supports the right rear wheel of the vehicle.

In the response delay absorbing device @B according to the present invention, a rod 12a of a valve body 12 protruding from a valve box 6 is fitted into a cylinder 17, and a spring 16 is interposed between the two to restrict relative movement between the two. That is, as in the case of the neutral return spring 10, a plurality of cylindrical parts 15 are formed extending in the axial direction across the fitting surfaces of the cylinder 17 and the rod 12a, and a pair of spring seats engaged with both ends of the cylindrical parts 15 are formed. A spring 16 is interposed between them. Preferably, three cylindrical portions 15 are arranged at equal intervals in the circumferential direction of the rod 12a.

Next, the operation of the response delay absorbing device for a hydraulic actuator according to the present invention will be explained. For example, when the handle is turned to the right, the valve box 6 is pulled by the connecting member 5 and returns to the neutral state by the spring 10.
Move to the right against the force of. Therefore, the central groove 8
is in communication with the groove 14, and the groove 9 is in communication with the groove 13. Pressure oil from the hydraulic pump 4 enters the end chamber 33 through the pipe 27, groove 8, groove 14, and pipe 19, and the piston 21 is pushed to the left. The tie rod 26 rotates the knuckle arm 24 counterclockwise about the support shaft 23, deflecting the rear wheel 22 to the left (in the opposite phase to the front wheel), thereby improving the turning ability of the vehicle when running at low speed. .

At this time, end'! The oil 132 is returned to the oil tank 3 through the pipe 20, the groove 13, the groove 9, and the pipe 28. Movement of tie rod 26 is transmitted to barrel 17 via remote cable 18. Roughly, the rod 12a is pulled to the right together with the cylindrical body 17 by the action of the strong spring 16. That is, when the valve body 12 moves to follow the valve body 6 and reaches the neutral state shown in FIG. 1, the operation of the hydraulic actuator C is stopped and the rear wheel 22 is maintained at that angle.

When the handle is turned to the left and returned to the straight-ahead position, first the valve box 6 moves to the left and a relative movement occurs between it and the valve body 12, and the pressure oil from the hydraulic pump 4 flows into the end chamber 32 of the hydraulic actuator C.
The oil in the end chamber 33 is returned to the oil tank 3. rear wheel 2
2 is returned to the straight forward position, the movement of the tie rod 26 is transmitted to the cylinder 17 via the remote cable 18, and the valve body 12 is pushed back to the left together with the cylinder 17, resulting in the state shown in FIG. .

By the way, when the handle is turned wide and fast, for example to the left, the valve body 6 is pushed to the left and hits the end flange 31 of the valve body 12, pushing the valve body 12 to the left. At this time,
Since the hydraulic pressure 7 actuator C does not work so that the piston 21 quickly moves to the right and pushes the valve body 12 to the left via the remote cable 18, the remote cable 18 does not work to push the valve body 12 to the left if there is no response delay absorber B. It may be pulled too hard by the body 12 and be damaged, or the handle may become difficult to operate. but,
According to the present invention, even if the valve body 12 is pushed to the left by the valve body 6, the spring 16 is bent and the cylinder body 17 is held in that position, and the remote cable 18 is not pulled too hard. In this way, smooth steering is ensured without any unnatural drag acting on the feedback remote cable 18 or even the steering wheel due to a delay in the response of the hydraulic actuator C.

[Effects of the Invention] As described above, the present invention includes a directional control valve for controlling a hydraulic actuator that includes a valve box and a valve body fitted into the valve box,
while connecting one of the valve body and the valve body to the input displacement transmission member;
Since the other side is connected to the operating member of the hydraulic actuator via a spring that expands and contracts within a predetermined range, the amount of relative movement between the valve body and the valve body of the directional control valve due to a delay in response of the operating part of the hydraulic actuator due to sudden operation of the handle. Even if the value exceeds the limit, the spring inserted between the valve body and the feedback remote cable flexes and absorbs the response delay, preventing damage to the remote cable or excessive drag being applied to the handle operation. Problem-free and smooth steering is ensured.

[Brief explanation of drawings]

FIG. 1 is a plan view of a rear wheel steering mechanism in a four-wheel steering vehicle equipped with a hydraulic actuator response delay absorbing device according to the present invention. A Two-way switching valve B: Response delay absorption device C: Hydraulic actuator 6: Valve box 12: Valve body 15: Cylindrical portion 16: Spring 18: Spacing cable 26: Tie rod

Claims (1)

[Claims] A directional switching valve for controlling a hydraulic actuator is composed of a valve box and a valve body fitted into the valve box, and one of the valve body and the valve body is connected to an input displacement transmission member, while the other is connected to an operating member of the hydraulic actuator. A response delay absorbing device for a hydraulic actuator, characterized in that the device is connected via a spring that expands and contracts within a predetermined range.