JPH0650287Y2 - Steering angle ratio control mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a steering angle ratio control mechanism for a four-wheel steering vehicle.

[Prior Art] In the four-wheel steering vehicle disclosed in Japanese Patent Laid-Open No. 55-91458,
By steering the rear wheels in the same phase when the front wheel steering angle is small, and by steering the rear wheels in the opposite phase when the front wheel steering angle is large, stable steering can be obtained when changing lanes at high speed. Improves maneuverability at low speeds. This 4
In a wheel steering vehicle, when a pin of an input rod moves back and forth in association with front wheel steering, the rear wheel is steered via a tie rod by the lateral movement of a sliding body having a planar S-shaped cam groove that engages with the pin. Further, in the one disclosed in JP-A-58-97565, a rear wheel is steered via a tie rod by a pin that operates in a trochoidal curved shape.

[Problems to be Solved by the Invention] In the four-wheel steering vehicle described above, the steering angle of the rear wheels is uniquely determined by the steering wheel operation amount. However, it is preferable to control the ratio of the rear wheel steering angle to the front wheel steering angle according to the driving conditions of the vehicle and the road conditions.

The purpose of the present invention is that the operating mechanism is simple and flat, it can be compactly installed under the floor, the rudder angle ratio can be changed arbitrarily, and when the rudder angle ratio control motor fails, the steering of the rear wheels is stopped. The present invention is to provide a steering angle ratio control mechanism that can continue driving safely.

[Means for Solving the Problem] In order to achieve the above-mentioned object, the structure of the present invention is provided with an arc-shaped groove in a control lever that rotates around a support shaft in association with front wheel steering, and the arc-shaped groove is provided. The rear end of the output link, which is connected to the groove via a sliding pin, is connected to a rear wheel steering member that can move back and forth, and a gear that is driven by a steering angle ratio control motor is engaged with a partial gear provided at the front end of the output link. A spring that biases the output link to a position where the sliding pin is arranged coaxially with the spindle of the control lever is provided on the connecting pin that removably meshes and connects the output link and the rear wheel steering member.

[Operation] When the front wheel is steered by the handle, the rod moves back and forth, and the control lever is rotated about the support shaft via the input link. An output link connected to the control lever via a sliding pin drives a rod as a rear wheel steering member back and forth to steer the rear wheel.

The rear wheel steering angle ratio is controlled by changing the connection point between the control lever and the output link, that is, by moving the sliding pin along the arcuate groove of the control lever.

When the steering angle ratio control motor is driven, the gear is driven, and the output link integrated with the partial gear that meshes with the gear rotates about the connecting pin with the rod, and the sliding pin moves.

When the steering angle ratio control motor fails, the gears driven by the steering angle ratio control motor are disengaged from the partial gears of the output link, and the sliding pin is coaxial with the spindle of the control lever. As a result, the output link is deactivated and the rear wheels are not steered even if the control lever is rotated.

[Embodiment of the Invention] FIG. 1 is a plan view showing a schematic configuration of a vehicle provided with a steering angle ratio control mechanism according to the present invention. The knuckle arms 3 that support the left and right front wheels 2 are rotatably supported on the vehicle body by a support shaft 3a, and are linked to each other by a tie rod 4. The arm of the right knuckle arm 3 is connected to the front wheel steering mechanism 7 via a drag link 10. In the front wheel steering mechanism 7, when the steering shaft 6 is rotated by the steering wheel 5, the output shaft 7a is rotated,
The drag link 10 is moved back and forth by swinging the drop arm 8 connected to the output shaft 7a. The front end of the rod 12 is connected to the pin 9 connected to the intermediate portion of the drop arm 8, and the rear end of the rod 12 is connected to the input link 14 of the steering angle ratio control mechanism A by the pin 13.

The input link 14 is connected to the end of the control lever 30 by a pin 15. A control lever 30 rotatably supported on a vehicle body by a support shaft 23 is connected to an output link 27 by a sliding pin 28. The output link 27 is connected to a rod 31 that moves back and forth by a connecting pin 27a. The rod 31 is connected to one valve element of the servo control valve 32 of the rear wheel steering mechanism 34. Rear wheel steering mechanism
34 includes a servo control valve 32 and an actuator integrally. The actuator has a piston 33 fitted in a cylinder 33, and an outer end or front end of a rod 31 connected to the piston 35 is supported by the vehicle body. The other valve element of the servo control valve 32 is integral with the cylinder 33 and connects the rod 36.

A rod 36 is attached to one end of a lever 37 supported by a spindle 38 on the vehicle body.
, And the rod 39 that moves back and forth is connected to the other end. The rear end of the rod 39 is a knuckle arm that supports the rear wheel 40.
Connected with 41 arms. The left and right knuckle arms 41 are interlockingly connected by a tie rod 42.

The control lever 30 of the steering angle ratio control mechanism A is provided with an arcuate groove 29 centered on the connecting pin 27a, and the sliding pin 28 is slidably engaged along the arcuate groove 29. In order to slide the sliding pin 28, a fan-shaped partial gear 22 is provided at the end of the output link 27.
Is integrally formed, and the gear 17 meshing with the partial gear 22 is driven by the steering angle ratio control motor 18. A worm shaft 21 of a steering angle ratio control motor 18 is meshed with a gear 16 coaxially connected to the gear 17. A frame that supports the steering angle ratio control motor 18 and the gear 17 is slid by an actuator 19 along a guide groove 20 of the vehicle body. The actuator 19 has a piston fitted into a cylinder, and the piston is a rod that controls the steering angle ratio control motor.
It is connected to the frame of 18 and is normally forward (gear 17
And a partial gear 22 are disengaged from each other).

The support shaft 23 of the control lever 30 has a groove continuous with the arc-shaped groove 29. When the lever 24 connected to the control lever 30 is rotated clockwise by the actuator 25, the groove of the support shaft 23 is cut off from the arcuate groove 29 of the control lever 30. Actuator
Reference numeral 25 is a cylinder in which a piston is fitted, and the piston and the lever 24 are connected by a rod. Normally, the lever 24 is pressed against the stopper 26 by the spring force of the actuator 25, and the groove of the support shaft 23 and the arcuate groove 29 of the control lever 30 are brought into a continuous state.

Now, when the steering wheel 5 is turned to the right, the drag link 10 of the front wheel steering mechanism 7 moves forward, and the knuckle arm 3 is pivoted.
The front wheel 2 is deflected rightward by rotating clockwise around 3a. At the same time, the rod 12 also moves forward and the control lever
30 rotates counterclockwise about the spindle 23. The output link 27 pulls the rod 31 forward and the servo control valve 32
By the action of, the pressure oil is supplied to the chamber on the front side of the actuator. The cylinder 33 moves forward, the rod 39 moves backward via the lever 37, the knuckle arm 41 rotates counterclockwise about the support shaft 41a, and the rear wheel 40 moves leftward (in the opposite phase to the front wheel). Biased. At this time, since the turning radius of the vehicle becomes small, the small turning ability at low speed traveling is improved.

When the gear 17 is rotated by the steering angle ratio control motor 18 in association with the vehicle speed and the output link 27 is rotated counterclockwise around the connecting pin 27a, the sliding pin 28 moves to the left side of the support shaft 23. At this time, the rear wheels 40 are deflected in the same phase as the front wheels 2 (see FIG. 2), and the steering stability when changing lanes at high speed is improved.

The electronic control unit 51 including a micro computer as a steering angle ratio setting means includes a vehicle speed sensor 55 arranged, for example, facing the output shaft of the transmission, and a front wheel steering angle sensor 59 arranged, for example, facing the tie rod 4. And a signal for driving the steering angle ratio control motor 18 is generated based on the respective signals from the steering angle ratio sensor 56 arranged to face the partial gear 22, for example.

3 and 4 are plan views showing a specific configuration of a mechanism for controlling the engagement of the output link 27 with the control lever 30 in the steering angle ratio control mechanism, and FIG. 5 is a side sectional view of the same. Fixed frame at the bottom of the car body
70 is provided with a pair of left and right guide grooves 20, and sliding plates are provided in the guide grooves 20.
63 is slidably engaged and driven by actuator 19. The rudder angle ratio control motor 18 is supported on the sliding plate 63, and the worm shaft 21 formed on the shaft of the rudder angle ratio control motor 18 meshes with the gear 16. The shaft 73 of the gear 16 penetrates to the lower side of the sliding plate 63, and another gear 17 (FIG. 5) is supported at the lower end thereof.
The fan-shaped output link 27 is disengageably engaged with the partial gear 22. That is, when the sliding plate 63 is moved backward in FIG. 3, the gear 17 meshes with the partial gear 22 (the state of FIG. 5), and the output link 27 is rotated about the support shaft 64.

However, instead of using the actuator 19, the output link
The support shaft 64 that supports the free-rotating 27 can be configured to rotate. In this case, the eccentric pin 64a of the support shaft 64 is engaged with the elongated hole 65 provided at the end portion of the sliding plate 63, and if the support shaft 64 is rotated 1/4 of the state shown in the figure, the radius of the support shaft 64 will be approximately the same. The sliding plate 63 moves rearward in the figure by the amount, and the gear 17 moves to the partial gear 22.
Mesh with.

When there is an electrical failure such as a break in the steering angle ratio control motor 18, the sliding plate
A spring mechanism for retracting 63 to disengage the gear 17 from the partial gear 22 is configured on the support shaft 64. The pin 66a is projected downward from the lever 66 connected to the eccentric pin 64a. On the other hand, as shown in FIG. 5, the pin 78 is projected upward from the support member 70b of the fixed frame 70a. Spring 67 wrapped around spindle 64
Both ends of the are locked to the pins 66a and 78.

As shown in FIG. 4, the spring 67 urges the pins 66a and 78 toward each other. At this time, the support shaft 64 is rotated together with the lever 66, and the eccentric pin 64a is biased forward (the uppermost position in the figure), so that the sliding plate 63 moves forward,
The mesh between the gear 17 and the partial gear 22 is released.

As shown in FIG. 5, the support shaft 64 is a rod as a steering member.
It is rotatably supported by a connecting pin 27a fixed to 31. The rod 31 is axially slidably supported by the guide member 71 in the groove of the fixed frame 70. The output link 27 is rotatably supported by the coupling pin 27a by the bearing 77. The sliding pin 28 connected to the lower surface of the end of the output link 27 causes the control lever 30 and the control lever 30 to
It is slidably engaged with an arcuate groove 29 of a support shaft 23 that rotatably supports. In the embodiment shown in FIG. 5, the sliding plate 63 and the sliding plate engaging with the support shaft 64 are separate bodies, but they may be integrated. The shaft 73 of the gear 16 is mounted on the sliding plate 63 by the thrust bearing 72.
Supported by.

When the steering angle ratio control motor 18 is out of order, the gear 17 and the partial gear 22 are disengaged from each other, and at the same time, the output link 27 is returned to the stationary position, that is, the position where the sliding pin 28 is aligned with the support shaft 23. A return mechanism is provided on the connecting pin 27a. Therefore, one end of a mainspring (not shown) is locked to a slit 79 provided at the upper end of the connecting pin 27a, and the other end is locked to a pin 76 connected to the output link 27. When the gear 17 driven by the steering angle ratio control motor 18 and the partial gear 22 of the output link 27 are disengaged by the mainspring, the output link 27 is automatically rotated around the connecting pin 27a and slides. The moving pin 28 is arranged coaxially with the support shaft 23. When the support shaft 23 is rotated while the sliding pin 28 is engaged with the groove of the support shaft 23, the output link 27 is fixed at that position, and the rear wheel is rotated even if the control lever 30 is rotated.
40 is not steered.

It should be noted that it is useful to dispose the steering angle ratio control motor 18 in the opening of the sliding plate 63 to reduce the height dimension, but the steering angle ratio control motor 18 is fixedly supported on the lower surface of the sliding plate 63. If the gear 17 is directly driven, the size can be further reduced, and the steering angle ratio control mechanism can be easily installed under the floor of the vehicle.

[Advantages of the Invention] As described above, the present invention is provided with an arc-shaped groove in the control lever that rotates about the support shaft in connection with the front wheel steering, and is connected to the arc-shaped groove through a sliding pin. The rear end of the output link is connected to the rear-wheel steering member that can move back and forth, and the gear driven by the steering angle ratio control motor is disengageably engaged with the partial gear provided at the front end of the output link. Since the connecting pin that connects the wheel steering member is provided with a spring that urges the output link to rotate to a position where the sliding pin is coaxial with the spindle of the control lever, a relatively small steering angle ratio control motor The output link of the angle ratio control mechanism can be driven to change the steering angle ratio arbitrarily. Since the drive mechanism is simple and flat, it can be easily installed even in a narrow space under the floor.

When the steering angle ratio control motor fails, the gear driven by the steering angle ratio control motor and the partial gear of the output link are separated, and the sliding pin is returned to the position aligned with the spindle of the control lever. The output link becomes inoperative, and the rear wheels are not steered even if the control lever rotates, so that the driving can be continued safely.

[Brief description of drawings]

FIG. 1 is a plan view showing a schematic configuration of a four-wheel steering vehicle equipped with a steering angle ratio control mechanism according to the present invention, FIG. 2 is an operation characteristic diagram of the steering angle ratio control mechanism, and FIG. FIG. 4 is a plan view showing a drive mechanism of an output link in the ratio control mechanism, FIG. 4 is a plan view of the relevant portion, and FIG. 5 is a side sectional view of the same. A: Steering angle ratio control mechanism, 17: Gear, 18: Steering angle ratio control motor, 2
2: Partial gear, 23: Support shaft, 27: Output link, 27a: Connecting pin,
28: Sliding pin, 29: Circular groove, 30: Control lever, 31: Rod, 63: Sliding plate

Claims (1)

[Scope of utility model registration request] 1. A control lever that rotates about a support shaft in association with front wheel steering is provided with an arcuate groove, and the rear end of an output link that is connected to the arcuate groove via a sliding pin is anteroposterior. A connection connecting a movable rear wheel steering member, a gear driven by a steering angle ratio control motor releasably engaged with a partial gear provided at the front end of the output link, and connecting the output link and the rear wheel steering member. A steering angle ratio control mechanism characterized in that a spring is provided on the pin to rotate and bias the output link to a position where the sliding pin is arranged coaxially with the spindle of the control lever.