JPH02120501A - Safeguard for negative feedback cable - Google Patents

Abstract

PURPOSE:To set the fluid-pressure circuit of a control valve back into a safe condition when a tensile spring absorbing extension or a negative feedback cable is involved in breakage by having the fluid-pressure circuit of the control valve set in a safe condition in association with the movement of a detecting member. CONSTITUTION:When a negative feedback cable 50 or a tensile spring 5 is involved in breakage, a bell crank 10 as a detecting member is rotationally moved due to force of a spring 12 in a clockwise direction around a supporting shaft 4 to put a safeguard into operation. Specifically, a normally-closed type open-close valve 39 is set open, which causes oil pressure supplied via a servo control valve (B) into a steering actuator (D) to be released and the steering actuator (D) to be set back into a neutral position by a return spring 45. At the same time the oil pressure of an actuater 55 is released which causes a piston 57 to be pressed down by a spring 56, a rocking member 52 to be engaged with a receiving member 49 and a real wheel 60 to be rocked at a straight-going position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cable safety device that provides negative feedback to a wJ device to control the operation of an actuator driven by a fluid pressure m device.

(Prior Art) In a four-wheel steering vehicle disclosed in Japanese Utility Model Application Publication No. 62-38781, each control valve of a front wheel steering mechanism and a rear wheel steering mechanism in which an actuator and a control valve are integrated is connected to each other by a remote cable. In such an actuator control device, when the remote cable is stretched, play occurs between the front wheel steering mechanism and the rear wheel steering mechanism, and the control accuracy of the rear wheel steering mechanism decreases.

Therefore, the ilJ control valve of the rear wheel steering mechanism is arranged adjacent to the front wheel steering mechanism so that it is directly driven in relation to the steering wheel operation, and the rear wheel control valve is connected to the control valve by a pipe. Preferably, the operating amount of the steering actuator is negatively fed back to the driven part of the control valve via a remote cable. Again, the load acting on the negative feedback cable or remote cable is slight, but as the remote cable stretches, the I#I control accuracy of the actuator decreases. Additionally, if the remote cable breaks, the actuator may erode.

[Same problem to be solved by the invention] In view of the above-mentioned problem, the object of the present invention is to absorb the elongation of the negative feedback cable in a timely manner, and to solve the problem when the tension spring that absorbs the elongation or the negative feedback cable breaks.
An object of the present invention is to provide a safety device for a negative feedback cable that returns the hydraulic circuit of a valve to a safe state.

[Means for Solving the Problems] In order to achieve the above object, the configuration of the present invention is such that the end of the negative feedback cable stretched between the actuating part of the actuator and the driven part of the control valve and the stopper are connected to each other. A tension spring is disposed between the detection member and the fixed part, and a weak spring is disposed between the detection member and the fixed part to bias the detection member away from the stopper, thereby preventing the detection member from moving. In conjunction with this, the fluid pressure circuit of the IiJ control valve is brought into a safe state.

[Operation] When the tension spring 5 or the negative feedback cable 50 is cut, the lever 10 or 10a as a detection member is pushed by the springs 12, 12a, and the safety device is activated in conjunction with the detection member. That is, the normally closed on-off valve 39 opens, the hydraulic pump 25 is communicated with the oil tank 26, the servo 1i1110 valve B returns to the neutral position, and the steering actuator D is returned to the neutral position by the return spring.

[Embodiments of the invention]

The present invention will be explained in the case of a rear wheel steering mechanism of a four-wheel steering vehicle. However, the present invention is not limited thereto, and is applied to a mechanism in which the operation of a hydraulic actuator operated by hydraulic or pneumatic pressure remotely operated by a servo control valve is negatively fed back to the servo control valve by a negative feedback cable. be done.

As shown in FIG. 1, when the input shaft 19 rotated in conjunction with the operation of the front wheel steering mechanism 30 is transmitted to the drive shaft 24 of the servo control valve B via the steering angle ratio 1lIIO mechanism A, the steering Actuator D is driven and rear wheel 60 is steered.

The amount of steering of the rear wheels 60 is negatively fed back to the servo control valve B via the negative feedback cable 50.

When the steering shaft 37 is driven by the handle 41, the output shaft 29 of the hydraulic front wheel steering mechanism 30 is rotated.
A drag link 33 is moved back and forth by a steering arm 32 projecting downward from the front wheel, and the front wheels are steered. At the same time, l! of the output shaft 29! i! 31 and the arm 36 of the input shaft 19 supported on the bracket 16 of the housing of the front wheel steering mechanism 30 are connected by a link 35, and the rotation of the output shaft 29 is caused by the rotation of the input shaft 19.
transmitted to. A protruding piece 22 extending radially from a control member 20 spline-fitted to the input shaft 19 can be engaged with a v-shaped notch 21a formed on the circumferential surface of a cup-shaped notch member 21 coupled to the drive shaft 24. Ru.

The gap between the notch 21 and the protruding piece 22 is adjusted by moving the control member 20 in the axial direction. For this reason, the fork-shaped lower end of the lever 18 supported on the vehicle body side by the support shaft 17 is engaged with the annular groove of the l control member 20, while the upper end is connected to the piston rod of the seven cutuator 15. The stroke of the actuator 15 is 611111 against the force of the spring 13 in relation to the vehicle speed. Therefore, when the handle 41 is used beyond a certain angle from the neutral position, the rotation of the input shaft 19 is transmitted to the drive shaft 24.

The servo control valve 8 is, for example, a rotary four-bottom neutral position open directional switching valve. When the drive shaft 24 is rotated, pressure oil from the hydraulic pump 25 flows through the pipe 27 and the servo 11m valves 8, 11.
42. End chamber 4 of steering actuator D via one of 43
6.48 and the oil in the other end chamber is supplied to one of the pipes 42.48.
The other side of 43, servo tIII! It is returned to the oil tank 26 via Il valve B and pipe 28. Therefore, the piston 47 fitted in the cylinder 44 of the steering actuator D is pushed to the right or left against the force of the return spring 45, and the rear wheel 60 is moved to the support shaft 58 via the tie rod 51 and the knuckle arm 59. deflected around the center.

At the same time as servo Ill III #B is activated,
The switching valve 38 is activated, pressure oil is supplied from the hydraulic pump 25 to the end chamber 53 of the cylinder 54 of the actuator 55 through the switching valve 38, the piston 57 is pushed up against the force of the spring 56, and the locking member 52 is opened. The tie rod 51 is disengaged from the receiving member 49.

According to the present invention, in order to provide negative feedback of the operating amount of the steering actuator D to the servo control valve B, one end of the negative feedback cable 50 is connected to the tie 51, and the other end is connected to the lever 9a of the driven shaft 6.
connected to the end of the In practice, the negative feedback cable 50 is inserted and guided through an outer tissue having one end fixed to the cylinder 44 of the steering actuator D and the other end fixed to the housing of the servo control valve B, for example.

An electromagnetic clutch C is constituted by a friction plate 9 that connects the lever 9a, a friction plate 7 that connects to the driven shaft 6, and an electromagnetic coil 8. When the electromagnetic coil 8 is excited, the friction plates 9 and 7 are frictionally engaged. , the rotation of the lever 9a is transmitted to the driven shaft 6.

A rotation amount in the same direction corresponding to the rotation amount of the drive shaft 24 is applied to the driven shaft 6, and the piston 47 of the steering actuator D stops at that position.

According to the present invention, the tension spring 5 is stretched between the lever 9a and the bell crank 10 as a detection member that abuts against the stopper 11, and the tension spring 5 is stretched between the bell crank 10 and the fixed part 14. A spring 12, which is weaker than the bell crank 10, is applied, and the spring 12 applies a rotational force to the bell crank 10 in a direction away from the stopper 11. The bell crank 10 and a normally closed on-off valve 39 connected between the hydraulic pump 25 and the oil tank 26 are interlocked and connected by the link 3.

Next, the operation of the safety device for the negative feedback cable according to the present invention will be explained. When servo t) J control valve B is in the neutral position, electromagnetic clutch C is disconnected. The tension spring 5 tensions the negative feedback cable 50 and removes the slack. When the servo control valve B operates from the neutral position, the electromagnetic clutch C is connected at the same time, and the operation of the steering actuator D is transmitted to the driven shaft 6 via the negative feedback cable 50 and the lever 9a.

When the negative feedback cable 50 breaks or the tension spring 5 breaks, the bell crank 10 as a detection member
It is rotated clockwise around the support shaft 4 by the force of 2,
Safety device is activated. Specifically, a normally closed on-off valve 39
is opened, thereby releasing the hydraulic pressure supplied to the steering actuator D via the servo IIIwA valve B, and the steering actuator D is returned to the neutral position by the return spring 45. At the same time, the hydraulic pressure of the actuator 55 is released, so the piston 57 is pushed down by the spring 56, the locking member 52 is engaged with the receiving member 49, and the rear wheel 60 is locked in the straight-ahead position.

In the embodiment shown in FIG. 2.3, the tension spring 5 is wound around the driven shaft 6. In the embodiment shown in FIG. One end 5b of the tension spring 5 is engaged with a lever 9a that locks the negative feedback cable 50, while the other end 5b is engaged with a lever 9a that locks the negative feedback cable 50.
A is latched to a lever 10a, which serves as a detection member, supported on the driven shaft 6 for free rotation independently of the lever 9a. Lever 1
0a is abutted against the rod 68 of the switch device 70.

The switch device 70 has a stepped rod 68 slidably supported on both end walls of a stepped housing 67, and a spring 1 is inserted between a spring seat 65 coupled to the stepped rod 68 and the end wall of the housing 67.
2a is inserted. A pair of fixed contact pieces 61, 62 on the end wall
is supported. A spring 64 is interposed between a movable contact piece 66 that is slidably supported within a predetermined range on a stepped rod 68 and a spring seat 65.

Normally, the lever 10 in FIG.
a is pressed against the O-rad 68, and the spring seat 65 is pressed against the stepped portion of the housing 67. At the same time, the lever 9a is urged to rotate clockwise about the driven shaft 6 by the force of the tension spring 5, and the negative feedback cable 50 is tensioned.

When the negative feedback cable 50 or the tension spring 5 breaks, the force that urges the lever 10a'2 to rotate in the counterclockwise direction is released, and the force of the spring 12a of the switch device 70 causes the
The stepped rod 68 is returned to the right together with the spring seat 65.

Therefore, the movable contact piece 66 separates from the fixed contact piece 61, 62, the circuit of the switch is opened, and a safety device (not shown) is activated electrically.

Although the above-mentioned embodiment describes the case of a hydraulic actuator, the present invention is also applicable to a pneumatic actuator.

[Effects of the Invention] As described above, the present invention provides a structure in which a negative feedback cable is connected between the end of the negative feedback cable that is stretched between the actuating part of the actuator and the driven part of the control valve, and the detection member that comes into contact with the stopper. , a tension spring is disposed between the detection member and the fixed part, and a weak spring is disposed between the detection member and the fixed part to urge the detection member away from the stopper, and the fluid pressure circuit of the control valve is activated in conjunction with the movement of the detection member. Because it is in a safe state, if the negative feedback cable breaks or the tension spring that tensions the negative feedback cable breaks, the detection member that was pressed against the stopper by the tension spring will be pushed by the spring and will move accordingly. Since the safety device is activated and the fluid pressure circuit of the tillll valve that controls the actuator is opened, abnormal operation of the actuator is prevented.

In this way, the actuator that is remotely controlled from the servo l1IIO valve adjacent to the fluid pressure source is controlled with high precision by the simple and inexpensive negative feedback cable, and the fluid pressure circuit is safe even if the negative feedback cable breaks. It works in the direction, so
As a remote control device using fluid pressure, inexpensive and highly accurate control can be obtained.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a safety device for a negative feedback cable applied to a four-wheel steering vehicle, and Fig. 2 is a side view of a safety device for a negative feedback cable according to a second embodiment of the present invention. Figure 3 is a front view of the same. h Feedback cable 51: Tie Od Patent applicant Isuzu Motors Co., Ltd.

Claims (1)

[Claims] A tension spring is disposed between the end of the negative feedback cable that is stretched between the operating part of the actuator and the driven part of the control valve, and the detection member that comes into contact with the stopper, and the tension spring is arranged between the detection member and the fixed part. A safety device for a negative feedback cable, in which a weak spring is disposed between the detection member and the stopper to urge the detection member away from the stopper, and the fluid pressure circuit of the control valve is brought into a safe state in conjunction with the movement of the detection member.