JPS6241894Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a four-wheel steering device that controls the steering of both the front wheels and the rear wheels through steering operation, and in particular changes the steering phase and steering ratio of the front and rear wheels. Concerning improvement of control mechanism.

In general, a four-wheel steering system installed on a vehicle controls the rear wheels according to the steering direction and steering angle of the front wheels. By steering the rear wheels in the same direction (same phase), the phase delay of the cornering force of the rear wheels with respect to the front wheels is shortened, making it easier to perform lane changes, etc., and also at low vehicle speeds. By setting the steering direction of the rear wheels in the opposite direction (opposite phase) to the steering direction of the front wheels,
The minimum turning radius of the vehicle is reduced to make it easier to park the vehicle in a garage.

By the way, in this type of four-wheel steering system, a control mechanism for changing the steering phase and steering ratio of the front and rear wheels according to vehicle speed, etc. has been conventionally developed, for example, in Japanese Patent Laid-Open No. 56
As disclosed in Publication No. 167562, etc., a steering device for steering the front wheels and a rear wheel steering device for steering backward rotation are connected via links parallel to each other in a direction perpendicular to the links ( The lever member is connected to a lever member having a rotation center (variable fulcrum) that is movable in the left-right direction of the vehicle, and the rotation center of the lever member is moved by a motor to determine the lever ratio, that is, from the rotation center of the lever member to each link. A system has been proposed in which the steering phase and steering ratio of the front and rear wheels are changed by changing the ratio of the distances to the connection point.

However, in the above proposal, since the steering phase and steering ratio of the front and rear wheels are changed by changing the lever ratio of the lever member, the overall length of the lever member naturally increases, and the linkage of the control mechanism becomes complicated. It was hot.

Therefore, in view of this point, the present invention moves the rotation center of the lever member connected to the steering device and the rear wheel steering device through the mutually parallel links in a direction perpendicular to the links as shown in the upper part. Rather, the direction and amount of movement of the lever member is controlled by moving it in a direction parallel to the link, thereby changing the steering phase and steering ratio of the front and rear wheels. The purpose is to simplify the linkage of

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

In FIG. 1, reference numeral 1 denotes a rack and pinion type steering device for steering left and right front wheels 2, 2, and the steering device 1 includes a steering wheel 3,
Rack and pinion mechanism 4, left and right tie rods 5,
5, and left and right knuckle arms 6, 6.

On the other hand, 7 is a rear wheel steering device that steers the left and right rear wheels 8, 8, and the rear wheel steering device 7 includes a rear wheel steering rod 9 that is slidable and extends in the left and right direction of the vehicle body; tie rods 10 and 10 at each end of
Left and right knuckle arms 11 connected via
It consists of 11.

A lever member 12 extending in the left-right direction of the vehicle body is disposed between the steering device 1 and the rear wheel steering device 7, and one end (left end) of the lever member 12 is connected to the rear end of a first I-shaped link 13 extending in the front-rear direction. are connected,
One end of a first L-shaped link 14 rotatably supported on the vehicle body is connected to the front end of the I-shaped link 13, and the other end of the L-shaped link 14 is connected to the steering device 1.
The rack 4a of the rack and pinion mechanism 4 is connected to the rack 4a of the rack and pinion mechanism 4. On the other hand, the other end (right end) of the lever member 12 is connected to the front end of a second I-shaped link 15 that extends in the longitudinal direction of the vehicle body in parallel with the first I-shaped link 13. One end of a second L-shaped link 16 rotatably supported on the vehicle body is connected, and the other end of the second L-shaped link 16 is connected to the rear wheel steering rod 9 of the rear wheel steering device 7, so that the lever member 12 are connected to the steering device 1 and the rear wheel steering device 7 via mutually parallel links 13 and 15 at different positions, respectively.

Further, the lever member 12 is rotatably supported by a slider 17 at a fulcrum O located at an intermediate portion thereof, and the slider 17 is screwed onto an output shaft 18a formed with a male thread extending in the front-rear direction of the motor 18. Both I-shaped links 13 and 15 are supported and rotated in the forward and reverse directions of the motor 18 to achieve a predetermined stroke range.
It is provided so that it can move in a direction parallel to (front-back direction).

Further, the motor 18 is connected to a battery power source 20 via a controller 19. The controller 19 also includes a vehicle speed sensor 21 that detects the vehicle speed, a steering direction sensor 22 that detects the steering direction applied to the steering wheel 3, a front wheel steering angle sensor 23 that detects the steering angle of the front wheels 2, and the rear wheels 8,
A total of four sensors, including a rear wheel steering angle sensor 24 that detects the steering angle of 8, are connected as inputs, and the controller 1
By changing the polarity of the voltage applied to the motor 18 and the amount of power supplied to the motor 18 by means 9, the direction and amount of movement of the mover 17 are controlled with respect to the steering direction and steering angle of the front wheels 2, 2. , 8 is configured to change the steering phase and steering ratio of the wheels.

Next, to explain the operation of the above embodiment,
For example, when the steering wheel 3 is turned and the front wheels 2, 2 are steered to the right, the first connection point _P1 between the first I-shaped link 13 and the lever member 12 is adjusted to the steering angle of the front wheels 2, 2, as shown in FIG. When the front and rear wheels 2, 8 are moved forward by a distance l ₁ corresponding to
_The fulcrum (O) _of When moved by the reference distance L (when the fulcrum O is at the center position of the lever member 12, L=1/2l ₁ ), the second connection point _P2 stops, and the rear wheels 8, 8 move to the front wheel 2. , 2 are not steered even though they are being steered, and as a result, the steering phase of the front and rear wheels 2, 8 becomes zero phase, and the steering ratio also becomes zero.

In addition, when the front and rear wheels 2 and 8 are set to have the same steering phase at medium or high vehicle speeds, if the mover 17 is moved forward by more than the reference distance L, the second connection point
By moving P ₂ forward, the rear wheels 8, 8 are steered in the same right direction as the front wheels 2, 2, and as a result, the steering phases of the front and rear wheels 2, 8 become the same.

On the other hand, when the steering phases of the front and rear wheels 2 and 8 are reversed at low vehicle speeds, if the mover 17 is moved forward or backward by less than the reference distance L, the second connection point P ₂ By moving rearward, the rear wheels 8, 8 are steered to the left, which is opposite to the front wheels 2, 2, and as a result, the steering phases of the front and rear wheels 2, 8 become opposite phases.

When the phase is the same and the phase is opposite, the moving distance l 2 of the second connection point P ₂ is increased or decreased by controlling the difference between the moving distance l of the moving element 17 and _the reference distance L.
The steering angle of the rear wheels 6, 6 is determined by the change in the steering angle, and thus the steering ratio of the front and rear wheels 2, 8 can be changed.

In addition, when the front wheels 2, 2 are steered to the left, contrary to the above, the first connection point _P1 moves rearward, and the mover 17 is moved in the same manner as in the above case according to the moving distance. By controlling the movement, the steering phase and steering ratio of the front and rear wheels 2 and 8 can be changed.

Therefore, in this way, the steering device 1
The center of rotation (fulcrum O) of the lever member 12 linked to the rear wheel steering device 7 is connected to the link 13,1.
To simplify the linkage of the control mechanism in order to change and control the steering phase and steering ratio of the front and rear wheels 2 and 8 while correcting the linkage of the lever member 12 by moving the lever member 12 in a direction parallel to the lever member 5. Can be done.

In the above embodiment, the links 13 and 15 are connected to both ends of the lever member 12, and the intermediate portion is supported by the slider 17, but one end of the lever member is supported by the slider and the setting It may be changed so that the links are connected to two positions spaced apart from each other, and this can be selected as appropriate depending on the space in the vehicle and the like.

Further, in the above embodiment, an electromagnetic motor was used as the motor, but other types of motors such as a vacuum motor may also be used, and a rack and pinion type steering device 1 was used as the steering device. Of course, other types of steering devices may also be used.

As explained above, according to the four-wheel steering system for a vehicle according to the present invention, two lever members are spaced apart by a set distance.
A steering device and a rear wheel steering device are connected to each other through links that are parallel to each other, and the fulcrum of the lever member is supported by a mover that is driven by a motor and moves in a direction parallel to the links. The direction and amount of movement of the movable element is controlled in relation to the steering direction and the steering angle, and the steering phase and steering ratio of the front and rear wheels are changed. The linkage of the control mechanism that changes and controls the steering ratio can be simplified.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being an overall schematic diagram and FIG. 2 being an explanatory diagram showing the operation of the lever member. 1...Steering device, 2...Front wheel, 7...
Rear wheel steering device, 8... Rear wheel, 12... Lever member, 13... First I type link, 15... Second I type link, 17... Mover, 18... Motor, 19...
Controller, O... fulcrum.

Claims (1)

[Scope of utility model registration request] A steering device that steers the front wheels, a rear wheel steering device that steers the rear wheels, and two points separated by a set distance are connected to the steering device and the rear wheel steering device via links parallel to each other, and a fulcrum. is a lever member rotatably supported by a slider that is driven by a motor and moves in a direction parallel to the link within a predetermined stroke range, and a lever member that is rotatably supported by a slider that is driven by a motor and moves in a direction parallel to the link, and a lever member that is rotatably supported by a slider that is driven by a motor and moves within a predetermined stroke range in a direction parallel to the link. A four-wheel steering system for a vehicle, comprising: a controller that issues a motor control signal that controls the amount of movement and changes the steering phase and steering ratio of the front and rear wheels.