JP2504089B2 - Steering angle ratio control mechanism - Google Patents

Description

The present invention relates to a steering angle ratio control mechanism for a four-wheel steering vehicle.

[Prior Art] In a four-wheel steering vehicle, the ratio of the rear wheel steering angle to the front wheel steering angle, that is, the steering angle ratio is changed according to the traveling conditions and road conditions. For example, in the steering angle ratio control mechanism disclosed in Japanese Patent Laid-Open No. 59-77968, a link interlocking with a front wheel steering member and a link interlocking with a rear wheel steering member are connected to a lever with a variable lever ratio, Is changed by the screw shaft. This rudder angle ratio control mechanism has a considerably long screw axis in the vehicle width direction, which limits the placement under the floor, and when the rudder angle ratio control motor that drives the screw shaft is electrically damaged, There is a problem that it is difficult to attach a mechanism for canceling the operation of the wheel steering mechanism.

[Problems to be Solved by the Invention] An object of the present invention is to provide a steering angle ratio control mechanism which has a compact overall shape, does not have the above-mentioned problems, and can be easily arranged under the floor of the vehicle body.

[Means for Solving the Problem] In order to achieve the above-mentioned object, the structure of the present invention has an arc-shaped groove provided in a control lever that rotates in association with front wheel steering,
A steering angle ratio control motor in which one end of the output link is connected by a sliding pin, the other end of the output link is connected by a connecting pin to the end of a relay lever that connects the rear wheel steering member, and is supported by the support shaft of the relay lever. An endless chain is spanned over a chain wheel driven by a chain wheel and a chain wheel which is connected to a connecting pin together with an output link.

[Operation] When the steering angle ratio control motor 18 is driven, the chain wheel 70 is driven together with the gear 64 that meshes with the worm shaft 63, and the endless chain.
The chain wheel 67 is rotated via 69. The output link 27 is rotated together with the chain wheel 67 connected to the connecting pin 68, and the sliding pin 28 is rotated.
Moves along the arcuate groove 29. As a result, the rotation about the support shaft 23 of the control lever 30 that rotates in association with the front wheel steering is converted to the rotation about the support shaft 62 of the relay lever 65 via the output link 27, and the rear The wheel steering member is driven back and forth.

The ratio of the forward / backward movement amount of the pin 27a of the relay lever 65 to the forward / backward movement amount of the pin 15 of the control lever 30 related to the front wheel steering is adjusted by the inclination of the output link 27.

[Embodiment of the Invention] FIG. 2 is a plan view showing a schematic configuration of a vehicle provided with a steering angle ratio control mechanism A 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 right arm of the knuckle arm 3 is connected to the front wheel steering mechanism 7 via the 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, and the drop arm 8 coupled to the output shaft 7a is moved to move the drag link 10 back and forth. A rod 12 is connected to a pin 9 connected to an intermediate portion of the drop arm 8, and a rear end of the rod 12 is connected to an input link 14 of the steering angle ratio control mechanism A by a 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 the vehicle body by a support shaft 23 is connected to one end of an output link 27 by a sliding pin 28 that engages with an arcuate groove 29. The other end of the output link 27 is connected to the end of the relay lever 65 by a connecting pin 68.
The relay lever 65, which is supported on the vehicle body side by the support shaft 62, is connected at its end portion to the rod 31 as a rear wheel steering member by a pin 27a.

The rod 31 is connected to one valve element of the servo control valve 32 of the rear wheel steering mechanism 34. The rear wheel steering mechanism 34 has a servo control valve 32.
And an actuator are integrated. The actuator consists of a piston 33 fitted in a cylinder 33.
The outer end of the rod 31 connected to the 35 is supported by the vehicle body. The other valve elements of the servo control valve 32 are integral with the cylinder 33 and connect the rod 36.

A rod is attached to one end of a lever 37 supported by a spindle 38 on the vehicle body.
36 is connected, 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. Left and right knuckle arms 41 are spindles 41
It is rotatably supported by the car body by a and
Are linked together.

The electronic control unit 51 including a microcomputer as a steering angle ratio setting means includes, for example, a vehicle speed sensor 55 arranged facing the output shaft of the transmission and a front wheel steering angle sensor 59 arranged facing the tie rod 4, for example. And a signal for driving the steering angle ratio control motor 18 is generated based on each signal from the steering angle ratio sensor 56 arranged so as to face the gear 64, for example.

As shown in FIG. 1, the steering angle ratio control mechanism A according to the present invention.
The control lever 30 is rotatably supported by the support shaft 23 on the board 61 fixed to the vehicle body side, and the relay lever 65 is rotatably supported on the board 61 by the support shaft 62. The control lever 30 is provided with an arcuate groove 29 centered on the connecting pin 68, and the base end side thereof can be connected to the groove 29a formed in the support shaft 23. One end of the output link 27 is connected to the control lever 30 by the sliding pin 28 that engages with the arcuate groove 28. The other end of the output link 27 is connected to the end of the relay lever 65 by a connecting pin 68.

The connecting pin 68 is rotatably supported by the relay lever 65, and fixedly supports the output link 27 and the chain wheel 67.
The support shaft 62 of the relay lever 65 supports the relay lever 65 in a freely rotatable manner, and also fixedly supports the chain wheel 70 and the gear 64. The worm shaft 63 of the steering angle ratio control motor 18 meshes with the gear 64. An endless chain 69 is bridged between the chain wheel 70 and the chain wheel 67.

A clutch that is operated electrically or manually is provided between the connecting pin 68 and the chain wheel 67, and when the coupling with the chain wheel 67 is released, the output link 27 is forced by a spring force (not shown),
It is preferable that the connecting pin 68 is biased counterclockwise about the connecting pin 68. However, this configuration is not directly related to the gist of the present invention and will not be described further.

Next, the operation of the steering angle ratio control mechanism according to the present invention will be described. In FIG. 2, when the handle 5 is turned to the right, for example, the drag link 10 of the front wheel steering mechanism 7 moves forward, the knuckle arm 3 rotates clockwise around the support shaft 3a, and the front wheel 2 moves to the right. Biased. At the same time, rod 12
Also move forward. When the input link 14 moves forward,
The control lever 30 rotates counterclockwise around the support shaft 23. The output link 27 also rotates the relay lever 65 in the counterclockwise direction about the support shaft 62, and the rod 31 moves forward.

By the action of the servo control valve 32, pressure oil is supplied to the chamber on the front side of the actuator. The cylinder 33 moves to the front, the rod 39 moves to the rear via the lever 37, and the knuckle arm moves.
41 rotates counterclockwise about the spindle 41a, and the rear wheel 40
Is deflected to the left (the opposite phase of the front wheels). At this time, since the turning radius of the vehicle becomes small, the small turning performance at low speed traveling is improved.

The pin 27a of the relay lever 65 connected to the rear wheel steering member with respect to the amount of movement of the pin 15 for rotating the control lever 30 in the longitudinal direction.
The ratio of the back-and-forth movement amount is adjusted depending on the inclination of the output link 27, that is, the engagement position of the sliding pin 28 with the arcuate groove 29.

The steering angle ratio control motor 18, which is driven in relation to the vehicle speed, has an endless chain 69 when the gear 64 is rotated clockwise, for example.
The output link 27 is also rotated in the clockwise direction together with the chain wheel 67 via, and the sliding pin 28 moves to the right along the arcuate groove 29,
The steering angle ratio becomes large. Chain wheel 70 and chain wheel 67 are relay lever 65
Since the support shaft 62 and the connecting pin 68 of the output link 27 are respectively supported, there is no problem with the rotation of the relay lever 65, and the output link 27 is continuously operated even when the control lever 30 is operating.
The tilt of is controlled.

When the output link 27 becomes uncontrollable due to an electrical failure of the steering angle ratio control motor 18, etc., if the output link 27 is separated from the chain wheel 67 by the clutch provided on the connecting pin 68, the output link 27 is separated by a spring. Is rotated clockwise, and the sliding pin 28 engages with the groove 29a of the support shaft 23. When the support shaft 23 is rotated, the groove 29a is cut off from the arc-shaped groove 29, and the output link 2
7 is locked in that position. In this state, control lever 3
Even if 0 is rotated, the relay lever 65 does not rotate, the rear wheel steering member is held at the neutral position, and the steering by the front wheel steering can be continued.

[Advantages of the Invention] As described above, the present invention connects one end of an output link to a rear wheel steering member by a sliding pin in an arcuate groove provided in a control lever that rotates in association with front wheel steering. The other end of the output link is connected to the end of the relay lever to be connected by a connecting pin, and the chain wheel driven by the steering angle ratio control motor supported on the support shaft of the relay lever and the connecting pin are connected together with the output link. Since the endless chain is chained to the chain wheel, the control lever, relay lever, output link, steering angle ratio control monitor are supported as a unit on the board, and the overall shape is compact, making it easy to place the vehicle under the floor. is there. Except for the sliding part between the sliding pin and the arcuate groove, there is no other sliding part, the operation is smooth, and there is no rattling, so highly accurate steering angle ratio control can be obtained.

It is possible to easily attach a mechanism for canceling the operation of the rear wheel steering mechanism when the steering angle ratio control motor is electrically broken down.

[Brief description of drawings]

FIG. 1 is a plan sectional view of a steering angle ratio control mechanism according to the present invention, and FIG. 2 is a plan view schematically showing a four-wheel steering vehicle including the steering angle ratio control mechanism. 18: Steering angle ratio control motor, 23: Support shaft, 27: Output link, 28: Sliding pin, 29: Arc groove, 30: Control lever, 61: Board, 62:
Support shaft, 64: Gear, 65: Relay lever, 67, 70: Chain wheel, 68: Connecting pin, 69: Endless chain

Claims (1)

(57) [Claims] 1. An end portion of a relay lever for connecting a rear wheel steering member, wherein one end of an output link is connected by a sliding pin to an arcuate groove provided in a control lever which rotates in relation to front wheel steering. The other end of the output link is connected by a connecting pin, and an endless chain is applied to the chain wheel that is driven by the steering angle ratio control motor supported by the support shaft of the relay lever and the chain wheel that is connected with the output link to the connecting pin. A steering angle ratio control mechanism characterized by being handed over.