JPH0285076A - Rear wheel steering controller - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rear wheel steering control tllll device for a four-wheel steering vehicle.

[Prior Art] In the four-wheel steering vehicle disclosed in Japanese Patent Application Laid-Open No. 59-6171, if the steering angle does not exceed a predetermined value (dead zone), even if the front wheels are steered, the rear wheels are not steered. When driving at low speeds, when you turn the steering wheel sharply, the rear wheels are also steered in the opposite phase to the front wheels, improving turning performance.At high speeds, even when you turn the steering wheel sharply, the rear wheel steering angle is limited. Excessive changes in vehicle body posture are suppressed and steering stability is ensured.

However, in the above-mentioned four-wheel steering vehicle, the steering angle (dead zone) until the rear wheels start to be steered is constant regardless of the vehicle speed, so if the width of the dead zone is wide, the steering stability at high speeds will be affected. Although this is improved, the ability to turn around at low speeds will be sacrificed.

In addition, in the case where the rear wheels are held in a neutral position @ (straight-ahead position) by spring force in the dead zone of the steering angle, the spring used to hold the rear wheels in the straight-ahead position against external forces is large, and the rear The wheel steering actuators will also be large.

In order to solve the above-mentioned problem, the present applicant has proposed that the steering angle until the rear wheels begin to be steered, that is, the width of the dead zone, is controlled in relation to the vehicle speed, and that in the dead zone, the rear wheels are brought to a straight-ahead position by a neutral lock mechanism. The application is for a four-wheel steering vehicle that can be maintained. According to this four-wheel steering vehicle, when driving at low speeds, the rear wheels are steered even if the steering wheel turning angle is small, improving maneuverability, and when driving at high speeds, the rear wheels are not steered unless the steering wheel turning angle is large. In the dead zone, the rear wheels are held in the straight-ahead position by the neutral lock mechanism, improving steering stability.

[Problem to be solved by the invention] However, when the width of the dead zone changes depending on the vehicle speed, the third
The neutral locking mechanism, which is a member of the system, must also operate by turning the steering wheel to a steering angle that corresponds to the vehicle speed. For example, if the steering angle exceeds the dead zone, the differential tiljI
If the neutral lock mechanism is not released before the O-valve operates, an unreasonable force will be applied to the rear wheel steering actuator. Conversely, if the steering angle returns to the dead zone, the differential 11JI
If the neutral locking mechanism does not operate after the rear wheel steering 7 actuator driven by the J valve returns to the neutral position, smooth locking operation of the neutral locking mechanism will be hindered.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to reverse the mutual operation order of a differential control valve and a third member driven by a steering angle ratio control mechanism having a dead zone due to the reciprocating operation of the steering angle ratio control mechanism. An object of the present invention is to provide a rear wheel steering wheel W device that operates.

[Means for Solving the Problem] In order to achieve the above object, the configuration of the present invention is such that one of the steering wheel, the rotating wheel that moves, and the drive shaft of the differential control valve that controls the rear wheel steering actuator is connected to the drive shaft according to the vehicle speed. a notch member that supports a radial protrusion that moves in the axial direction in association with the cutout member that extends horizontally in the axial direction and has a notch that can be engaged with the protrusion that extends in the axial direction; A switch that opens and closes by moving the axis against the spring of the member is provided opposite to the notch member.

[Operation] When the steering angle exceeds the dead zone, when the protruding piece 22 of the rotating shaft 19 comes into contact with the notch member 21 of the drive shaft 24, the notch member 21 moves in the axial direction against the force of the spring 137. Therefore, the switch 23 is activated (ON), and in conjunction with the switch 23, the neutral locking mechanism H serving as the third member is released.

When the notch member 21 hits the stopper 135, the differential control valve B
The drive shaft 24 of the rear wheel steering actuator F is rotated, and the rear wheel steering actuator F is operated.

On the other hand, when the steering wheel turning angle returns to the dead zone, the drive shaft 24 of the differential control valve B is returned to the neutral position by the force of the neutral position return spring 134, and at the same time, the notch member 21
Rotates to follow. After the rear wheel steering actuator F is returned to the neutral position, the notch member 2 is moved by the force of the spring 137.
1 moves axially, the switch 23 is activated (OFF), and the neutral locking mechanism H serving as the third member is locked.

Embodiment of the Invention FIG. 2 is a schematic diagram of a four-wheel steering vehicle equipped with a steering angle ratio 1j control mechanism according to the present invention. The four-wheel steering vehicle includes a steering angle ratio control mechanism A that transmits the rotation of a rotating shaft 19 interlocked with an output shaft 29 of a front wheel steering mechanism 30 to a differential control valve B in relation to vehicle speed, and a rear wheel steering actuator F. Hydraulic circuit to 1lJII
the differential I control valve B that drives the rear wheels 71, the rear wheel steering actuator F that drives the rear wheels 71, and the steering angle ratio control mechanism A 1lJi11.
It is equipped with an electric/hydraulic 1111 control scissor holder C for driving the member 20.

Steering angle ratio #JIl1 mechanism A includes a control member 20 spline-fitted to a rotating shaft 19 and a drive shaft 24 that drives a differential control valve B.
It consists of a cup-shaped cutout member 21 coupled to. The drive shaft 24 is aligned coaxially with the rotating wheel 19.

A protruding piece 22 extending in the radial direction from the control member 20 is configured to be able to engage with a horizontal notch 21 a formed on the circumferential surface of the notch member 21 .

In order to adjust the position of the cutout member 21 of the projection piece 22, the III control lever 18 of the shaft 17 is engaged with the annular groove of the control member 20, and the control member 20 is slid in the axial direction by rotation of the control lever 18. be done. The lever 19a of the shaft 17 rotatably supported on the li body side is connected to the piston rod of the actuator D and rotated.

Actuator D that drives I control member 20 is driven by electric/hydraulic control 0fIWIC, which will be described later.

The actuator D is partitioned into an end chamber into which hydraulic pressure is introduced and an atmospheric chamber by a piston fitted inside the cylinder. The spring 13 housed in the atmospheric chamber applies a rotational force to the lever 18a and the I control lever 18, moves the 6111111 member 20 in the axial direction, and acts to remove the protruding piece 22 to a position where it cannot engage with the notch 21a. .

The differential control valve B is a four-bottom neutral position open type or block type directional switching valve, and has a spool 126 fitted inside the valve housing 122 so as to be movable in the axial direction against the force of a neutral return spring. , are coupled to the screw shaft 130 by a coupling means 136a so as to move together in the axial direction. Screw shaft 1
The right end of the lead 30 is screwed into a screw hole 131 having a large lead thread groove 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 spool 126 undergoes axial movement as the drive shaft 24 rotates, the hydraulic pump 26
Pressure oil is supplied from the pipe 72.75 to one of the pipes 76.80, and the oil in the other pipe is supplied to the oil tank 2 via pipe 79.77.
Returned to 8. The tube 76.80 communicates with the end chamber 89.91 of the rear wheel steering actuator F.

In the rear wheel steering actuator F, a piston 56 is fitted into a cylinder 57, end chambers 89 and 91 are defined, and the piston 5
A tie rod 65 coupled to the cylinder 57 is projected outward from both end chambers of the cylinder 57. The tie rod 65 is at the end '189.9
The rear wheel 71 is returned to the neutral position by the force of the return spring 55 housed in the rear wheel 71, and the rear wheel 71 is held in the straight-ahead position. Both ends of the tie rod 65 are connected to rear wheel knuckles 69 via auxiliary rods 67, respectively.
connected to. A rear wheel knuckle 69 that supports the rear wheel 71 is rotatably supported by the vehicle body by a vertical support shaft 70.

In order to more reliably hold the neutral position of the tie rod 65, a neutral locking mechanism H is provided which includes a receiving member 58 having a conical hole or groove coupled to the tie rod 65, and a locking member 59 that can be engaged with the receiving member 58. Actuator G
When pressure oil is supplied to the end chamber 96 of the cylinder 63 , the locking member 59 is separated from the receiving member 58 by the piston 64 against the force of the spring 61 .

The movement of the tie rod 65 is transmitted as rotation to the driven shaft 6 via the cable 50 connected between the receiving member 58 and the lever 9a. The driven wheel 6 acts independently of the drive shaft 24 to rotate the threaded shaft 130 and return the spool 126 to the neutral position.

FIG. 3 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, for ease of explanation, an actuator D is connected to a control lever 18 of a shaft 17, and a spring 13 is disposed externally. Further, an electromagnetic clutch 11 is provided between the driven shaft 6 and the lever 9a.
is provided.

When the electromagnetic coil 8 is excited, the friction plate 9 integrated with the lever 9a is frictionally engaged with the friction plate 7 coupled to the driven shaft 6.
Rotation of the lever 9a is transmitted to the driven shaft 6. When the electromagnetic clutch 11 is disconnected, the lever 9a is freely rotated by the spring 5 hooked between the lever 9a and the bell crank 10, and the slack in the cable 50 is removed. As is well known, in reality, the cable 50 is slidably inserted into an outer tube that has one end fixed to the vehicle body side and the other end fixed to the housing side of the rear wheel steering actuator F.

As shown in FIG. 2, the electric/hydraulic control device C moves the control member 20 of the steering angle ratio control mechanism A in the axial direction, and adjusts the circumferential gap between the protrusion 22 and the notch 21a in relation to the vehicle speed. Control. For this reason, the electric/hydraulic all device C has the control member 20
The actuator D that drives the 1110 lever 18 that engages with the actuator D, the oil amount adjustment valve E that adjusts the stroke of the actuator D, that is, the amount of oil to the actuator D, and the current to the electromagnetic coil 47 that drives the oil amount adjustment valve E. and a current subtraction converter 45 that converts the current into a single section in relation to the vehicle speed.

Oil 1! II valve regulator ε has a housing 4 with three boats
A spool 48 having two annular grooves is fitted into the inside of the actuator D, and an end chamber 49 housing a spring 49a and a central boat communicate with the end chamber of the actuator D. In the neutral position, the boat on the right that communicates with the annular groove of the spool 48 is the pipe 7.
8. The boat on the left goes to the hydraulic pump 26 via 72 and the pipe 7
3.77 to the oil tank 28, respectively. An O-rad 48a coupled to the spool 48 protrudes to the outside of the housing 46 to form an armature, and is biased to the left by the electromagnetic coil 47 against a spring 49a in response to the current. The electromagnetic coil 47 is connected to the power source battery 51 in series with a current subtraction converter 45, which has a large current when the vehicle speed is low, and a current decreases as the vehicle speed increases. A gear mechanism 4 is attached to a flexible shaft 43 that transmits the rotation of the output shaft of the transmission to the speedometer 15.
2 to a vehicle speed proportional current generator 144. Both terminals of the vehicle speed proportional current generator 44 are connected to a current subtraction converter 45 .

As shown in FIG. 1, according to the present invention, the spline hole 21b provided in the end wall of the notch member 21 is fitted into the small diameter shaft portion 24a of the drive shaft 24 so as to be movable in the axial direction, and is engaged with the small diameter shaft portion 24a. It is supported by a retaining ring 138 so that it does not come off. Stopper 13 consisting of a flange formed on drive shaft 24
5 and the end of the notch member 21! A spring 137 is interposed between it and 21c. A switch 23 is arranged on a bracket 122a that protrudes from the valve housing 122 of the differential control valve B, and this movable contact piece 23a is located at the end! 21c, and the notch member 2
It is opened and closed by one axial movement.

A pin 139 parallel to the drive shaft 24 is coupled to the seventh flange 133 of the drive shaft 24, while a pin 140 parallel to the drive shaft 24 is fixed to the bracket 122a. Drive shaft 2
Both ends of the neutral return spring 134 wound around the pin 139
The pin 140 is engaged with the pin 140 between the pins 140 and 140. The neutral return spring 134 applies a restoring force to the drive shaft 24 to the neutral position in the rotational direction, and the differential control valve B is restored to the neutral position.

As shown in FIG. 2, the electromagnetic switching valve 52 that connects the end chamber 96 of the actuator D to one of the hydraulic pump 26 and the oil tank 28 is switched by opening and closing the switch 23.

Next, the operation of the four-wheel steered vehicle equipped with the steering angle ratio control mechanism according to the present invention will be explained. In FIG. 2, for example, when the steering wheel 41 is turned to the right, the output shaft 29 of the front wheel steering mechanism 30
is rotated, the drag link 33 is pulled forward by the arm 32, the front wheel knuckle 38 is rotated clockwise about the support shaft 34, and the front wheel 4o is deflected to the right. At the same time, the rotation of the output shaft 29 is transmitted to the rotation shaft 19, and when the vehicle speed is below a predetermined value and the steering angle exceeds the dead zone,
The protruding piece 22 of the rotation shaft 19 abuts against the notch 21a of the notch member 21. At this time, the neutral position return spring 1 is attached to the notch member 21.
Since the load torque of 34 is acting and the notch 21a is horizontal, the notch member 21 moves to the left against the force of the weak spring 137 regardless of whether the handle is turned to the right or left. . The movable contact piece 23a is pressed and the switch 23 is turned on. The electromagnetic switching valve 52 (Fig. 2) is activated, pressure oil is supplied from the hydraulic pump 26 to the end chamber 96 of the actuator G, the locking member 59 is separated from the receiving member 58 by the piston 64, and the neutral locking mechanism H is released. be done.

When the end 121c of the cutout member 21 hits the stopper 135,
The rotation of the protruding piece 22 is transmitted to the drive shaft 24 via the notch member 21. The driven shaft 6 does not rotate with respect to the rotation of the drive shaft 24 and prevents the rotation of the screw shaft 130. Therefore, a axial thrust commensurate with the lead angle of the screw hole 131 is generated on the screw shaft 130, and the driven shaft 6 is rotated along with the screw shaft 130. Spool 126 moves to the right. With the axial movement of the spool 126, pressure oil is supplied from the hydraulic pump 26 to the end v89 of the actuator F via the pipes 72, 75 and the differential I control valves 811!76. The tie rod 65 is pushed to the right together with the piston 56, and the rear wheel knuckle 6
9 is rotated counterclockwise about the support shaft 70, and the rear wheel 71 is deflected to the left (in the opposite phase to the front wheel 40). In this way, the vehicle's ability to turn in a tight corner while traveling at low speeds is exhibited. End room 9
The oil of No. 1 is returned to the oil tank 28 through the pipe 80, the differential l1lJIll#B, and the pipe 77.

When the vehicle speed is low, as described above, a large current flows from the power supply battery 51 to the electromagnetic coil 47 via the current subtraction converter 45, so that the spool 48 of the oil amount adjustment valve E is moved to the left until it balances the force of the spring 49. pushed to. Pressure oil from the hydraulic pump 26 passes through pipes 72, 78 and is supplied from the annular groove on the right side of the spool 48 to the end chamber of the actuator D via the pipe 49b. The oil pressure in the end chamber 49 increases, and the spool 48 is returned to the right. In this way, the amount of oil sent to the actuator D is controlled in proportion to the current of the electromagnetic coil 47.

When the rond of the actuator D moves to the right, the control member 20 moves to the left with respect to the rotary wheel 19, so the gap in the circumferential direction between the protrusion 22 of the control member 20 and the notch 21a of the notch member 21 becomes narrower. Become. Therefore, when the handle 41 is slightly rotated from the neutral position, the protruding piece 22 moves into the notch 21.
a, the rotation of the rotation shaft 19 is transmitted to the drive shaft 24, the differential control valve B is operated, and the rear wheel steering actuator F steers the rear wheels 71.

When the vehicle speed is high (when the current in the electromagnetic coil 47 decreases, the spool 48 of the oil amount control valve E is temporarily returned to the right by the force of the spring 49a, and the oil in the pipe 49b flows into the annular groove on the left side of the spool 48). , and is returned to the oil tank 28 via pipes 73 and 77.As the vehicle speed increases, the current flowing to the electromagnetic coil 47 decreases, and the spool 48 of the oil amount adjustment valve E temporarily returns to the right, causing the actuator to The amount of oil flowing into D decreases, and the force of the spring 13 moves the rond back to the left.As a result, the control member 20 moves to the right with respect to the rotation shaft 19.It has been in contact with the notch 21a until now. The protruding piece 22 separates from the notch 21a, and the notch member 21 is rotated to return to the neutral position by the action of the neutral return spring 134 provided in the notch member 21.

In reality, the drive shaft 2 is rotated by the amount by which the notch member 21 is returned to the neutral position while remaining in contact with the protruding piece 22 in the notch 21a.
A screw movement occurs between the screw hole 131 of No. 4 and the screw shaft 130, the spool 126 is returned to the left, and the tube 75 is connected to the tube 80, and the tube 7
9 are connected to the tubes 76, respectively. 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. Cable 5 moves tie rod 65 to the left.
Since the driven shaft 6 is rotated through 0, when the screw shaft 130 returns to the rightward neutral position, the tie rod 65 is held at that position.

When the steering angle returns to the dead zone, neutral return 134
The cutout member 21 and the drive shaft 24 are exposed to the force of the projecting piece 2.
Rotate to follow 2. When the drive shaft 24 returns to the neutral position, the engagement force between the notch 21a and the protruding piece 22 becomes smaller, and the notch member 21 is returned to the right by the force of the spring 137 and hits the retaining ring 138. The movable contact piece 23a is restored, the switch 23 is turned off, the electromagnetic switching valve 52 is returned to the illustrated position, and the end chamber 96 of the actuator G is communicated with the oil tank 28. Therefore, the locking member 59 is secured to the receiving member 58 by the piston 64 receiving the force of the spring 61, and the neutral locking mechanism H is locked.

To explain the above operation with reference to FIG.
There is a dead zone until the angle corresponding to 1 is reached, and the rear wheels are not steered. When the steering wheel is further turned while the vehicle speed remains constant, the rear wheel steering angle gradually increases along line a1. If the front wheel steering angle becomes 63 and the rear wheel steering angle becomes α1 and the vehicle speed increases, the dead zone increases from the equivalent of the front wheel steering angle θ1 to the equivalent of the front wheel steering angle θ2 corresponding to the vehicle speed, and the front wheel steering angle remains constant. (
θ3), the rear wheel steering angle changes to α1 as the vehicle speed increases.
It decreases from α2 to α2. The steering angle ratio (the ratio of the rear wheel steering angle to the front wheel steering angle) moves onto the line a2 corresponding to the vehicle speed at that time, and changes along the line a2 according to the steering wheel turning angle. Therefore, as shown in FIG. 5, the steering angle ratio gradually decreases as the vehicle speed increases.

In addition, although the above-mentioned example explained the cooperative operation of the steering angle ratio control mechanism and the neutral lock mechanism as the third member, the present invention is not limited to this, and can also be applied.

[Effects of the Invention] As described above, the present invention provides a rotating wheel and a rear wheel steering actuator that are linked to a steering wheel! A radial protrusion that moves in the axial direction in relation to the vehicle speed is supported on one side of the drive shaft of the differential control valve controlled by II, and a radial protrusion that can be engaged with the protrusion that spreads laterally in the axial direction is supported on the other side. A notch member having a notch is supported so as to be movable in the axial direction, and a switch that opens and closes by the axial movement of the notch member against the spring is provided opposite to the notch member, so that if the handle turning angle exceeds the dead zone, the protruding piece When it comes into contact with the horizontal notch in the member, the notch member moves axially against the spring force, and until it hits the stopper, the switch is only activated and the notch member is not rotated, so there is no rotation before the rear wheel steering actuator is activated. When the third member is actuated and the steering angle returns to the dead zone, the axial movement of the notch member due to the spring force occurs only when the rear wheel steering actuator returns to the neutral position.
As the switch is actuated, the third member is reversely actuated. Therefore, even if the width of the dead zone of the steering wheel changes in relation to the vehicle speed, the switch that is linked to the axial movement of the notch member will
A smooth cooperative operation between the rear wheel steering actuator and the third member is achieved.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a rear wheel steering 11JIa device according to the present invention, FIG. 2 is a schematic configuration diagram of a four-wheel steering vehicle equipped with the same rear wheel steering control device, and FIG. 3 is a diagram of a steering angle ratio control mechanism. FIG. 4.5, which is a perspective view showing the main parts, is a diagram showing the steering angle characteristics of the steering angle ratio control mechanism. Neutral lock mechanism 19: Rotation shaft 21: Notch member 21a
: Notch 21b spline hole 22: Projection piece 23: Switch 24: Drive shaft 41: Handle 134: Neutral return spring 135: Stop collar 137: Spring patent applicant Isui Jidosha Co., Ltd.

Claims (1)

[Claims] A radial protrusion that moves in the axial direction in relation to vehicle speed is supported on one side of the rotating shaft that interlocks with the steering wheel and a drive shaft of the differential control valve that controls the rear wheel steering actuator, and a radial protrusion that moves in the axial direction in relation to the vehicle speed is supported on the other side. A notch member having a notch that can be engaged with the protruding piece that expands into a wedge shape is supported so as to be movable in the axial direction, and a switch that opens and closes by axial movement of the notch member against a spring is provided opposite to the notch member. Rear wheel steering control device.