JPH0781607A - Wheel steering gear - Google Patents

Abstract

PURPOSE:To provide a steering gear in which an actuator having small drive force is usable. CONSTITUTION:A wheel steering gear is provided with a suspension S having a pair of front and rear support arms 21, 22 as suspension arms which are placed apart in such a manner as deviating in the front and rear direction respectively to a rotation central axis line L1 of a wheel 30, extended in the wheel width direction, and at their respective outer ends, pivoted on a carrier 25 for rotatably and pivotally mounting the wheel 30. It is also formed with a lever 26 which is extended in the front and rear direction of the vehicle, pivoted to respective inner ends of both support arms 21, 22 at both front and rear ends, and of which approximately central part is journaled to the vehicle body so as to rotate in a plane vision and an actuator 40 which is incorporated in the vehicle body and connected to a lever 26 so as to move the lever 26 rotationally.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension having a pair of front and rear support arms as suspension arms (for example, double wishbone suspension).
The present invention relates to a wheel steering device configured by effectively utilizing

[0002]

2. Description of the Related Art This type of wheel steering system can be used as a rear wheel steering system for a four-wheel steering vehicle, one of which is proposed in, for example, Japanese Patent Laid-Open No. 62-91377. The wheel steering device disclosed in this publication is configured to displace one of the inner ends of both suspension arms, which are displaced forward and rearward with respect to the center axis of rotation of the wheel, in the vehicle width direction by an actuator. Is configured to obtain.

[0003]

In the wheel steering system disclosed in the above publication, both suspension arms are displaced forward and rearward with respect to the center axis of rotation of the wheel. Although it is possible to increase the toe angle rigidity by increasing the longitudinal distance between the ends, part of the kingpin shaft will pass through the connecting part of the carrier and the outer end of the suspension arm that is not displaced by the actuator, and the kingpin shaft will Since the wheel greatly separates from the wheel grounding position in plan view, the wheel has to be largely laterally displaced in the course of steering, which requires an actuator having a large driving force. The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a wheel steering device that can use an actuator having a small driving force.

[0004]

In order to achieve the above-mentioned object, in the present invention, the wheel steering device is offset from the center axis of rotation of the wheel in the forward and rearward directions, respectively. A suspension that includes a pair of front and rear support arms that are pivotally attached to a carrier that extends in the width direction and rotatably supports wheels at each outer end, as suspension arms,
Attached to the vehicle body with a lever that extends in the vehicle front-rear direction and is pivotally attached to the inner ends of the support arms at both front and rear ends and has a substantially central portion pivotally supported by the vehicle body so as to be rotatable in a plan view. The actuator is connected to the lever and rotates the lever.

[0005]

In the wheel steering system according to the present invention, the kingpin shaft passes through the intermediate portion between the outer ends of the two support arms due to the above structure, and the grounding position of the kingpin shaft is close to the wheel grounding position. Can be made. Therefore, when the actuator is actuated and the lever is rotated, one of the support arms is displaced to the right and the other is displaced to the left, and the kingpin axis passing through the intermediate portion between the outer ends of the support arms is rotated. The carrier is steered to give the wheel a steering angle with almost no lateral displacement.
Therefore, the wheels can be steered with a small driving force, and the wheel steering device can be configured using an actuator with a small driving force, so that the wheel steering device can be reduced in size and weight.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. 1 to 3 show a wheel steering device according to the present invention.
It shows an example of use as a rear wheel steering device of a wheel steering vehicle, and this device is configured by effectively utilizing a suspension S having a pair of front and rear support arms 21 and 22 as suspension lower arms. Suspension S is
A double wishbone suspension comprising a pair of front and rear support arms 21, 22, a single upper arm 23, and a radius rod 24.
Reference numerals 22 denote lower arms 25a of a carrier 25, which are offset from the center axis L1 of rotation of the wheel 30 in the front and rear directions and extend in the vehicle width direction to rotatably support the wheel 30 at each outer end. , 25b ball joint BJ
1 and BJ2, and the upper arm 23 has rubber bushes B on the vehicle body 10 at both inner ends.
1, B2, and the outer end is pivotally attached to the upper arm 25c of the carrier 25 via a ball joint BJ3, and the radius rod 24 is connected to the vehicle body 10 at the front end.
To the arm (not shown) of the carrier 25 at the rear end.
It is connected through 4.

In this suspension S, a straight line L21 passing through the outer end connecting portion of the front support arm 21 at a neutral position (straight running position) and orthogonal to the arm 21 in plan view and a rear support arm 22 are shown. An intersection O1 with a straight line L22 that passes through the outer end connecting portion and is orthogonal to the arm 22 in a plan view
Is a substantially intermediate portion between both support arms 21 and 22,
The straight line connecting the intersection O1 and the outer end connecting portion of the upper arm 23 is the kingpin axis L2 as shown in FIG. As shown in FIG. 2, the grounding position of the kingpin shaft L2 is displaced rearward by a predetermined amount d from the center O2 of the wheel 30,
The wheel 30 is close to the ground contact position, and the rearward displacement amount d is substantially equal to that of the pneumatic trail.

By the way, in the present embodiment, as shown in FIG. 1, the inner ends of both supporting arms 21 and 22 are respectively located at the front and rear swinging ends of the lever 26 at a rubber bush (a ball joint is also possible) B5. , B6. The lever 26 extends in the front-rear direction of the vehicle, and its substantially central portion is shown in FIGS. 1 and 3 so as to be rotatable behind the rotation center axis L1 of the wheel 30 by a predetermined amount d in plan view. As described above, it is rotatably supported by the vehicle body 10 via a rubber bush (which can be a bearing) B7 which can be twisted and deformed. The lever 26 is connected to a tie rod 41 of an actuator 40 mounted on the vehicle body via a ball joint BJ4, and is rotated by the operation of the actuator 40. The positions of the rubber bushes B5 and B6 are optimum for alignment in consideration of compliance steer, roll steer, and the like, and the connecting position of the lever 26 and the tie rod 41 considers the output and stroke of the actuator 40. It is considered to be the optimum position.

The actuator 40 is used in the illustrated wheel 30.
And the wheels (not shown) are simultaneously steered in the same direction. The tie rod 41 and the tie rod 41
Rack shaft (not shown) connected at one end to the inner end of
A pinion shaft (not shown) for moving the rack shaft in the vehicle width direction, an electric motor (not shown) for rotationally driving the pinion shaft, and a left lever (not shown) connected to the other end of the rack shaft. The tie rods (not shown) are connected to each other, and the rotation of the electric motor is controlled by an electronic control unit (not shown) in response to steering of the front wheels, for example.

In the present embodiment constructed as described above, the kingpin shaft L2 passes through the intermediate portion between the outer ends of the support arms 21, 22 as described above, and the grounding position of the kingpin shaft L2 is set to the wheel. It can be brought close to the grounding position. Therefore, when the actuator 40 is operated to rotate the lever 26, both support arms 21, 22 are rotated.
One of them is displaced to the right and the other is displaced to the left, so that the carrier 25 is steered around the kingpin axis L2 passing through the intermediate portion between the outer ends of the two support arms 21 and 22, whereby the wheels 30 are rotated. The rudder angle is provided with almost no lateral displacement. Therefore, the wheels 30 can be steered with a small driving force, and the wheel steering device can be configured by using the actuator 40 with a small driving force, and the wheel steering device can be reduced in size and weight. it can. Further, in the present embodiment, the center of rotation of the lever 26 is aligned with the pneumatic trail, which also improves the toe rigidity.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a wheel steering system according to the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a sectional view taken along line 3-3 of FIG.

[Explanation of symbols]

10 ... Vehicle body 21, 22 ... A pair of front and rear support arms, 25
… Carrier, 26… Lever, S… Suspension, 30
... wheel, L1 ... wheel rotation center axis line, L2 ... kingpin shaft, 40 ... actuator.

Claims (1)

[Claims] 1. A front and a rear of a wheel, which are offset from each other with respect to a center axis of rotation of the wheel, are spaced apart from each other forward and rearward, extend in the vehicle width direction, and are pivotally attached to a carrier rotatably supporting the wheel at each outer end. A suspension including a pair of support arms as suspension arms, and a vehicle body extending in the front-rear direction of the vehicle and having a substantially central portion that is pivotally attached to the inner ends of the support arms at both front and rear ends and is rotatable in a plan view. A lever pivotally supported by
A wheel steering system comprising an actuator mounted on a vehicle body and connected to the lever to rotate the lever.