JP2705137B2 - Actuator feedback mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a feedback mechanism for transmitting an operation amount of, for example, a rear wheel steering actuator in a four-wheel steering vehicle to a differential control valve.

[Prior Art] In a four-wheel steering vehicle disclosed in Japanese Utility Model Laid-Open Publication No. 62-38781, a front wheel steering actuator and a rear wheel steering actuator are each integrally provided with a hydraulic control valve. When the hydraulic control valve of the front wheel steering actuator is driven by the handle, the hydraulic control valve of the rear wheel steering actuator is interlocked via a cable. In the above-described four-wheel steering vehicle, the steering actuators incorporated in the front and rear wheel suspension mechanisms respectively perform complicated movements independently, so that the cables connecting the front and rear wheel hydraulic control valves are also required to perform complicated movements. If the cable becomes loose, smooth and accurate rear wheel steering corresponding to front wheel steering cannot be obtained.

In order to solve the above problem, the hydraulic control valve of the rear wheel steering actuator is disposed adjacent to the front wheel steering mechanism,
It is preferably operated directly by the handle. Even in this configuration, it is necessary to transmit a feedback signal corresponding to the operation amount of the rear wheel steering actuator to the hydraulic control valve.

[Problems to be Solved by the Invention] An object of the present invention is to provide a feedback mechanism of an actuator in which the cable always has no slack and the operation amount of the rear-wheel steering actuator is accurately and smoothly transmitted to a differential control valve. It is in.

[Means for Solving the Problems] To achieve the above object, the configuration of the present invention provides a valve element of a differential control valve for controlling a hydraulic circuit of an actuator via a clutch which is cut off at a neutral position of the actuator. The driven member is connected, and a slack removing spring is provided between an end portion of a cable connected to the driven member from the operating member of the actuator and a fixed portion.

[Operation] When the valve element 126 of the differential control valve B is driven by the drive shaft 24 as a drive member of the valve element that operates in association with the handlebar 27, a hydraulic circuit is generated to activate the rear wheel steering actuator F. The tie rod 65, which is an operation member, is driven together with the piston 56. The operation amount of the tie rod 65 is transmitted to the lever 9a as a driven member via the cable 50, and further transmitted to the driven shaft 6 via the electromagnetic clutch 11, and acts to return the valve element 126 to the neutral position. In this manner, the tie rod 65 is operated in accordance with the turning angle of the handle 27.

When the tie rod 65 of the rear wheel steering actuator F is in the neutral position, the electromagnetic clutch 11 is shut off, and the operation of the cable 50 is not transmitted to the driven shaft 6. The cable 50 is tensioned by the anti-loosening spring 5, and the slack of the cable 50 is removed. Therefore, when the rear wheel steering actuator F operates,
The amount of movement of the tie rod 65 passes through the electromagnetic clutch 11 and the driven shaft 6
Accurately transmitted to

[Embodiment of the Invention] The present invention will be described for the case of a rear wheel steering device in a four-wheel steering vehicle. As shown in FIG. 1, the four-wheel steering system includes a front wheel steering mechanism 30 operated by a steering wheel 27, a steering angle ratio control mechanism A driven in association with the operation of the steering wheel 27,
A differential control valve B driven by a steering angle ratio control mechanism A, a rear wheel steering actuator F whose hydraulic circuit is controlled by the differential control valve B, and a neutral locking mechanism H for holding the rear wheels at a neutral position; An actuator G for driving the locking member 59 of the neutral locking mechanism H, and a feedback mechanism C for transmitting the operation amount of the tie rod 65 driven by the rear wheel steering actuator F to the differential control valve B.

When the steering shaft 37 is rotated by the handle 27, the arm 32 of the output shaft 29 swings, and the drag link 33
, The front wheel nut 38 is rotated about the vertical support shaft 34, and the front wheel 40 is deflected rightward or leftward.
The front wheel knuckle supporting the left front wheel (not shown) is also linked by the tie rod 39. The arm 31 of the output shaft 29 and the arm 36 of the input shaft 19 supported by the bracket 16 (see FIG. 2) on the housing of the front wheel steering mechanism 30 are linked by a link 35.

The steering angle ratio control mechanism A includes a control member 20 spline-fitted to the input shaft 19 and a notch member 21 connected to a drive shaft 24 for driving the differential control valve B. The drive shaft 24 is arranged coaxially with the input shaft 19. A protrusion 2 extending in the radial direction from the control member 20 is formed in a wedge-shaped notch 21a formed on the peripheral surface of the
2 is configured to be engageable. Shaft 17 in annular groove of control member 20
The control lever 20 is engaged, and the control member 20 is slid in the axial direction by the rotation of the control lever 18. A lever 18a of the shaft 17 rotatably supported on the vehicle body side is connected to a piston rod 44 of the actuator D.

Actuator D separates a working chamber into which hydraulic pressure is introduced and an atmosphere chamber by piston 41 fitted inside cylinder 42. The lever 18a and the control lever 18 are rotationally urged by a spring 43 housed in the atmosphere chamber, and separate the projection 22 of the control member 20 from the notch 21a of the notch member 21 in the axial direction.

In the steering angle ratio control mechanism A, the control member 20 moves in the axial direction, and controls the circumferential gap between the protruding piece 22 and the notch 21a in relation to the vehicle speed. Therefore, the amount of oil to the actuator D that drives the control lever 18 that is engaged with the control member 20 is controlled by an oil amount adjustment valve (not shown), and the current to the electromagnetic coil that drives the oil amount adjustment valve changes the vehicle speed. Is controlled in relation to

The differential control valve B is a four-port neutral position open type or block type directional control valve, and is fitted inside the housing 122 so as to be axially movable against the force of a neutral return spring (not shown). An element (spool) 126 is coupled for axial movement with the screw shaft 130 by coupling means 136a. The right end of the screw shaft 130 is screwed into a screw hole 131 having a large screw groove of a lead formed at the end of the drive shaft 24.
The driven shaft 6 is spline-fitted into a spline hole 132 formed at the left end of the screw shaft 130.

When the drive shaft 24 is rotated, the driven shaft 6 and the screw shaft 130 rotationally connected thereto do not rotate unless the rear wheel 71 responds to the steering angle. This causes an axial thrust corresponding to the lead angle of the thread groove on the screw shaft 130, and the valve element 126 moves in the axial direction together with the screw shaft 130.

When the valve element 126 moves axially with the rotation of the drive shaft 24, hydraulic oil is supplied from the hydraulic pump 26 to one of the pipes 76 and 80 via the pipe 72, and the oil of the other pipe is supplied to the oil via the pipe 77. It is returned to the tank 28. Tubes 76 and 80 are end chambers 89 of rear wheel steering actuator F,
Communicated with 91.

The rear wheel steering actuator F has a cylinder 57 and a piston 56
Are fitted to define end chambers 89 and 91, and tie rods 56 connected to the piston 56 project outward from both end chambers of the cylinder 57. The tie rod 65 is a return spring 55 housed in the end chambers 89 and 91.
This force is urged to the neutral position to hold the rear wheel 71 in the straight traveling position. Both ends of the tie rod 65 are connected to a rear wheel knuckle 69 via auxiliary rods 67, respectively. A rear wheel nut 69 supporting the rear wheel 71 is rotatably supported by the vehicle body by a vertical support shaft 70.

In order to more reliably maintain the neutral position of the tie rod 65, a neutral locking mechanism H including a receiving member 58 having a conical hole or a groove connected to the tie rod 65 and a lock member 59 engageable with the receiving member 58 is provided. When pressure oil is supplied to the end chamber 96 of the cylinder 63 of the actuator G, the locking member 59 is separated from the receiving member 58 by the piston 64 against the force of the spring 61.

FIG. 2 is a perspective view showing the relationship between the front wheel steering mechanism 30, the steering angle ratio control mechanism A, and the differential control valve B. In FIG. 2, the actuator D is connected to the control lever 18 of the shaft 17 and the spring 43 is disposed outside for the sake of simplicity.

According to the feedback mechanism C of the present invention, the cable 50 is connected between the tie rod 65 of the rear wheel steering actuator F and the lever 9a supported on the driven shaft 6 so as to freely rotate. As is known, in practice, the cable 50 has one end on the vehicle body side and the other end on the housing 57 of the rear wheel steering actuator F.
Are slidably inserted through the outer tubes respectively fixed to the outer tubes. To remove slack in cable 50,
A slack removing spring 5 is stretched between the end of the lever 50 or the lever 9a and the fixed portion.

In the embodiment shown in FIG. 2, the slack removing spring 5 is locked to an end of a bell crank 10 rotatably supported by a shaft 49 on the vehicle body side, and the bell crank 10 is abutted against a stopper 48.
In the event that the cable 50 is cut, the bell crank 10 is rotated by the force of the spring 46 spanned between the bell crank 10 and the fixing part 47, and the solenoid valve (not shown) is activated via the link rod 45. When activated, the solenoid valve shuts off the hydraulic pressure source from the differential control valve B.

An electromagnetic clutch 11 is provided between the driven shaft 6 and the lever 9a. When the electromagnetic coil 8 is excited, the friction plate 9 integrated with the lever 9a is frictionally engaged with the friction plate 7 connected to the driven shaft 6, and the rotation of the lever 9a is transmitted to the driven shaft 6.

Next, the operation of the four-wheel steering system according to the present invention will be described. As shown in FIG. 1, when the handle 27 is in the straight traveling position, the notch member 21 is in the neutral position, the control valve B is also in the neutral position, the tie rod 65 of the rear wheel steering actuator F is in the neutral position, and the rear wheel 71 is in the neutral position. It is in a straight position. When the notch member 21 is at the neutral position, the switch 23 is opened, the electromagnetic coil 8 is demagnetized, and the electromagnetic clutch 11 is shut off. At this time, since the cable 50 is tensioned by the force of the slack removing spring 5 and slack is removed, when the electromagnetic clutch 11 is connected, the operation amount of the tie rod 65 is smoothly and reliably transmitted to the lever 9a.

For example, when the steering wheel 27 is turned to the right, the output shaft 29 of the front wheel steering mechanism 30 is rotated, the drag 33 is pulled forward by the arm 32, and the front wheel nut 38 is rotated clockwise about the support shaft 34. , The front wheel 40 is deflected to the right. At the same time, the rotation of the output shaft 29 is transmitted to the input shaft 19, and when the vehicle speed is below a predetermined value and the steering angle or the front wheel steering angle exceeds the predetermined value, the projecting piece 22 of the control member 20 , And the drive shaft 24 is rotated. At this time, the notch member 21 moves very slightly in the axial direction, the switch 23 closes, the electromagnetic coil 8 is excited and the electromagnetic clutch 11 is connected, and at the same time, the electromagnetic valve (not shown) is driven by the switch 23. The actuator G of the neutral locking mechanism H is driven, and the locking member is
59 is separated from receiving member 58.

With the rotation of the drive shaft 24 together with the screw shaft 130 the valve element 126
Moves to the right. The driven shaft 6 does not rotate, and prevents the screw shaft 130 from rotating. With the axial movement of the valve element 126, hydraulic oil is supplied from the hydraulic pump 26 to the end chamber 89 of the rear wheel steering actuator F via the pipe 72, the differential control valve B, and the pipe 76. Piston 56
The tie rod 65 is pushed to the right with the rear wheel nut 69
Is rotated counterclockwise about the support shaft 70, and the rear wheel 71 is deflected to the left (opposite phase with the front wheel 40). Thus, the small turning performance of the vehicle at low speed traveling is exhibited. End chamber 91 oil pipe
80, the oil is returned to the oil tank 28 via the differential control valve B and the pipe 77.

The operation of the tie rod 65 is transmitted to the lever 9a via the cable 50. At this time, the electromagnetic clutch 11 is in the connected state, the rotation of the lever 9a is transmitted to the screw shaft 130 via the driven shaft 6, and the valve element 126 is neutralized together with the screw shaft 130 with respect to the screw hole 131 of the drive shaft 24. Returned to position. As described above, when the operation amount of the tie rod 65 corresponding to the turning angle of the handlebar 27 is obtained, the valve element 126 returns to the neutral position, and the rear wheel steering actuator F is held at that position.

When the vehicle speed is low, the amount of oil supplied to the working chamber of the actuator D is large, and when the piston rod 44 of the actuator D moves to the right, the control member 20 moves to the left with respect to the input shaft 19; The circumferential gap between the 20 projections 22 and the notch 21a of the notch member 21 is reduced. Therefore, just by slightly rotating the handle 27 from the neutral position, the protruding piece 22 abuts the notch 21a, the rotation of the input shaft 19 is transmitted to the drive shaft 24, and the differential control valve B is operated. Wheel steering actuator F
As a result, the rear wheel 71 is steered.

As the vehicle speed increases, the amount of oil to the actuator D decreases, and the piston rod 44 is returned to the left by the force of the spring 43. The control member 20 moves rightward with respect to the input shaft 19. The protruding piece 22 that has been in contact with the notch 21a
The notch member 21 is rotated to return to the neutral position by the action of a neutral return spring (not shown) provided on the notch member 21.

Actually, with the notch 21a kept in contact with the protruding piece 22, the notch member 21 is screwed between the screw hole 131 of the drive shaft 24 and the screw shaft 130 by the amount of rotation returned toward the neutral position, The valve element 126 is returned to the left, and tube 72 is connected to tube 80, and tube 77 is connected to tube 76. The piston 56 of the rear wheel steering actuator F is returned to the left, and the steering angle of the rear wheel 71 is reduced. Since the leftward movement of the tie rod 65 rotates the driven shaft 6 via the cable 50, when the screw shaft 130 returns to the neutral position to the right, the tie rod 65 is held at that position.

The above operation will be described with reference to FIG. 3. When the vehicle is at the vehicle speed indicated by the line a1, the dead zone is defined until the steering wheel 27 is turned from the neutral position to an angle corresponding to the front wheel steering angle θ1, and the rear wheels are not steered. When the steering wheel 27 is further turned with the vehicle speed kept constant, the rear wheel steering angle gradually increases along the line a1. If the vehicle speed increases when the front wheel steering angle is θ3 and the rear wheel steering angle is α1, the dead zone increases from the front wheel steering angle θ1 equivalent to the front wheel steering angle θ2 equivalent to the vehicle speed, and the front wheel steering angle is constant. However, as the vehicle speed increases, the rear wheel steering angle becomes α
It becomes smaller from 1 to α2. The ratio of the rear wheel steering angle to the front wheel steering angle moves on a line a2 corresponding to the vehicle speed at that time, and changes along the line a2 according to the turning angle of the steering wheel 27.

In the above-described embodiment, the rotational motion related to the steering wheel 27 is added as an input to the differential control valve B, and the operation amount of the rear wheel steering actuator F is used as the rotational motion as the driven shaft 6.
Is transmitted to

As shown in FIG. 4, the input signal related to the steering wheel 27 and the feedback signal related to the operation of the rear wheel steering actuator F can be applied to the differential control valve B as a linear motion. At the end of rod 144 coupled to valve element 126,
A pinion 143 is rotatably supported, and a pair of racks 142 and 145 are engaged with the pinion 143. To move the rack 142 axially relative to the handle 27, the drive shaft 24
Is engaged with the rack 142. Further, a pinion 146 connected to the driven shaft 6 is engaged with the rack 145.

In this embodiment, when the handle 27 is turned to the right, the pinion
141 rotates counterclockwise, rack 142 moves to the right, and pinion 143 rotates clockwise at the same time, rod 144
With this, the valve element 126 moves rightward, and pressure oil is supplied to the end chamber 89 of the rear wheel steering actuator F. At this time,
145 remains stopped.

When the tie rod 65 of the rear wheel steering actuator F is driven, the pinion 146 of the driven shaft 6 rotates counterclockwise via the cable 50, and the rack 145 moves to the left. The rack 145 causes the pinion 143 to rotate clockwise, and the rod 14
With 4, the valve element 126 moves to the left and returns to the neutral position.

In the above embodiment, the case where the differential control valve is of the sliding valve element type has been described. However, the present invention can be applied to a rotary valve element type differential control valve.

[Effect of the Invention] As described above, the present invention couples a driven member to a valve element of a differential control valve that controls a hydraulic circuit of an actuator via a clutch that is shut off at a neutral position of the actuator,
A slack-releasing spring is provided between an end of a cable connected from an operating member of the actuator to a driven member and a fixed portion. When the driving member of the valve element is in the neutral position, the electromagnetic clutch is shut off, and the actuator is closed. Since the slack of the cable connecting the operating member of the valve element and the driven member of the valve element is removed by the slack removal spring, the operation amount of the operating member of the actuator is always transmitted to the driven member reliably, and the differential control valve Can be obtained smoothly.

According to the present invention, even if the differential control valve and the hydraulic unit are arranged at a distance from the actuator, the differential control valve and the actuator are merely connected to the hydraulic conduit and the cable, and are not limited to the rear wheel steering mechanism. Smooth remote control of the actuator is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of a four-wheel steering device provided with a feedback mechanism for an actuator according to the present invention, FIG. 2 is a perspective view of a main part of the four-wheel steering device, and FIG. 3 shows a steering angle characteristic of the four-wheel steering device. FIG. 4 is a plan sectional view showing a partially modified example of the apparatus. A: steering angle ratio control mechanism, B: differential control valve, C: feedback mechanism, D: actuator, F: rear wheel steering actuator, G:
Actuator, H: neutral locking mechanism, 5: loosening spring,
6: driven shaft, 8: electromagnetic coil, 9a: lever, 11: electromagnetic clutch, 50: cable, 65: tie rod, 126: valve element (spool)

Claims (1)

(57) [Claims] A cable connected to a valve element of a differential control valve for controlling a hydraulic circuit of an actuator via a clutch that is shut off at a neutral position of the actuator, and connected from an operating member of the actuator to the driven member. A feed-back mechanism for the actuator, wherein a slack removing spring is bridged between the end of the actuator and the fixed part.