JPH0362584B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a four-wheel steering system for a vehicle that controls the steering of the rear wheels in accordance with the steering of the front wheels. This invention relates to an improvement in a linkage mechanism that links rudder operations.

(Prior Art) Conventionally, as a four-wheel steering system for this type of vehicle, a steering system for steering the front wheels and a drive for a hydraulic actuator have been disclosed, for example, in Japanese Unexamined Patent Publication No. 57-11173. and a rear wheel steering device that steers the rear wheels by the front wheel steering angle, and controls the operation of the hydraulic actuator according to the front wheel steering angle and the vehicle speed, so that the rear wheel steering angle characteristics relative to the front wheel steering angle are adjusted to the vehicle speed. There are known devices that change the amount depending on the situation.

However, in the conventional system described above, since the rear wheels are controlled by driving a hydraulic actuator, the hydraulic control system becomes complicated, and the probability of failure increases accordingly, making it insufficient in terms of operational reliability. It was hot.

On the other hand, conventionally, a rod that moves back and forth in the axial direction according to the operation of the steering device has been disclosed in Japanese Patent Laid-Open No. 56-163969, etc., which has excellent operational reliability. By connecting and fixing a cam plate and slidably fitting a pin of a rear wheel steering rod that steers the rear wheels into a cam groove of a predetermined shape on the cam plate, the rear wheels can be adjusted according to the turning angle of the front wheels. A system in which the steering angle is changed with constant characteristics has been proposed.

(Problem to be Solved by the Invention) However, in this proposal, since the cam plate that engages with the rear wheel steering rod is integrally fixed to the rod that interlocks with the steering device, the front wheel steering angle However, the rear wheel steering angle characteristic (steering ratio) remains the same regardless of the vehicle speed, which has led to poor usability.

Therefore, the present invention has been developed by attaching the cam plate in the above-mentioned proposed example to the rod so as to be rotatable, and by variably controlling the angle formed between the cam groove direction of the cam plate and the moving direction of the rod, thereby changing the rear wheel rotation relative to the front wheel steering angle. It is an object of the present invention to make it possible to vary the rolling ratio of the front and rear wheels in accordance with the vehicle speed with a simple and highly reliable structure by changing the steering angle characteristics.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a steering device for turning the front wheels, a rear wheel steering device for steering the rear wheels, and a control device for controlling the rear wheel steering device. Equipped with a controller.

The rear wheel steering device includes a case, two rod members on the front wheel side and the rear wheel side, which are substantially perpendicular to each other and are supported by the case so as to be slidable in the axial direction, and are connected to the front and rear wheels, respectively. A guide plate is rotatably supported by one of the two rod members and has a guide groove, and a guide plate is attached to the other rod member and slidably fitted into the guide groove of the guide plate, The interlocking pin member slides in the guide groove of the guide plate by the axial movement of the side rod member, and the deflection angle (cross and an actuator for changing the direction and amount of relative movement of the rear wheel rod member in the axial direction with respect to the axial movement of the front wheel rod member.

Further, the controller is configured to issue a control signal to the actuator of the rear wheel steering device to variably control the rotational position of the guide plate so as to change the rear wheel steering angle characteristic with respect to the front wheel steering angle.

(Function) With the above configuration, in this invention, by operating the actuator of the rear wheel steering device by the controller, the guide plate supported by one of the rod members is rotated, and the guide groove of the guide plate is rotated. The deflection angle with the front wheel side rod member is changed, and the relative movement direction and amount of movement of both rod members in the axial direction is changed. That is, when the front wheel rod member moves in the axial direction as the front wheel is steered, the linking pin member integrated with the other rod member slides within the guide groove in the guide plate on the one rod member side. As the guide plate rotates due to the operation of the actuator, the guide groove of the guide plate rotates by a predetermined angle from the neutral position parallel to the front wheel rod member, and when the guide groove is in the neutral position, the front wheel rod member is free from movement. First, the rear wheel rod member does not move in the axial direction, but when the guide groove is inclined at an angle with the front wheel rod member from its neutral position, the rear wheel rod member moves in the axial direction in conjunction with the axial movement of the front wheel rod member. The rod member also moves axially. At that time, by changing the direction and angle of inclination of the guide groove with respect to the front wheel rod member, even if the movement of the front wheel rod member is the same, the movement direction and amount of movement of the rear wheel rod member will change. The steering phase of the wheels can be changed.

In this invention, the front and rear wheels are mechanically connected via both rod members and the guide plate, so the rear wheels can be steered to follow the front wheels with a simple structure, and the operation reliability is improved compared to the hydraulic type. You can improve.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 shows a schematic configuration of a first embodiment of a four-wheel steering system for a vehicle according to the present invention, in which 1 indicates left and right front wheels 2,
The steering device 1 comprises a steering wheel 3, a 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 for steering left and right rear wheels 8, 8, and the rear wheel steering device 7 is configured to steer both rear wheels 8, 8.
A case 9 is fixed to the vehicle body at an intermediate portion between the two cases, and a case 9 extends vertically and substantially perpendicularly to each other within the case 9 in the front-rear direction and left-right direction of the vehicle, and is slidable in the axial direction. A rack 12 is provided with two attached first and second rod members 10 and 11, and is formed at the front end of the first rod member 10 in the longitudinal direction.
The pinion 4a of the rack pinion mechanism 4 is engaged with the lower part of the pinion 4a, and the front wheels 2, 2 are engaged with the lower part of the rack pinion mechanism 4.
The first rod member 10 is moved back and forth in accordance with the steering of the vehicle. On the other hand, the second
The rod member 11 constitutes a rear wheel steering rod for steering the rear wheels 8, 8, and has left and right tie rods 1 at both ends thereof.
3, 13 to the left and right knuckle arms 14, 1.
4 are connected, and the rear wheels 8, 8 are steered by driving the second rod member 11 in the axial direction. Therefore, the first and second rod members 10, 11
are connected to the front and rear wheels 2 and 8, respectively.

First rod member 10 inside the case 9
As shown in FIG. 2, a horizontal base plate 15 is integrally attached to the first rod member 10, which is divided into front and rear parts, at approximately the center of the rod member 10 (the one in the front and back direction). Fixed.
Between the base plate 15 (first rod member 10) and the second rod member 11 below it, there is a guide plate 16 having a linear guide groove 16a on its lower surface (the surface facing the second rod member 11). The guide plate 16 is rotatably supported by the base plate 15 at its center via a support shaft 17 in a horizontal plane.

In addition, the second rod member 11 (the one in the left-right direction) inside the case 9 has a portion that intersects with the first rod member 10 when the steering angles of the front and rear wheels 2 and 8 are both zero, as shown in Fig. 3 (enlarged). As shown in detail, a linking pin member 18 that projects upward and slidably fits into the guide groove 16a of the guide plate 16 is connected to the bearing 1.
It is rotatably attached via 9. The linking pin member 18 has a rectangular base 20 rotatably supported by the second rod member 11, and a pair of rotatable and diagonally arranged rectangular bases 20 at each of the four corners of the base 20 in a horizontal plane. Four vertical shafts 21, 21, . Rollers 22, 22, . . . that roll due to contact with each other
and a spring 2 which moves and urges the pair of movable shafts 21, 21 to press the rollers 22, 22, . . . against the side walls of the guide groove 16a with a predetermined pressing force.
3, 23, and slides within the guide groove 16a by the rolling of the rollers 22, 22, .

Furthermore, a motor 24 as an actuator capable of forward and reverse rotation is fixed to the upper surface of the base plate 15, and a worm gear 25 attached to a rotating shaft 24a of the motor 24 is connected to the base plate 15.
It meshes with a sector gear 26 attached to the upper end of a support shaft 17 that protrudes upward from 5. and,
The guide plate 16 is rotated within a predetermined angle range by the operation of the motor 24, and the left and right deflection angle α (|α|<90°) of the guide plate 16 (guide groove 16a) with respect to the first rod member 10 is adjusted. By changing the direction and amount of movement of the second rod member 11 in the axial direction relative to the movement of the first rod member 10 in the axial direction, the guide plate 16 is moved upward with respect to the first rod member 10. When the second rod member 11 is in the opposite phase position A rotated clockwise when viewed from the front, the second rod member 11 is moved in the forward direction of the first rod member 10
to the left, and to the right for backward movement. On the other hand, the first rod member 10
When the first rod member 10 is in the same phase position B rotated counterclockwise when viewed from above, the first rod member 10
The second rod member 11 is moved to the right when the rod is moved forward, and to the left when the rod is moved backward. Furthermore, when the second rod member 10 is at the zero phase position C parallel to the first rod member 10, the second rod member 1
1 is configured to stop and hold.

Furthermore, 27 is a controller for controlling the operation of the rear wheel steering device 7, and the controller 27
A front wheel steering angle sensor 28 that detects the turning angle of the front wheels 2, 2 and a vehicle speed sensor 29 that detects the vehicle speed are connected as inputs. Then, the controller 27
Based on the output signals from both the sensors 28 and 29, the motor 24 (actuator) of the rear wheel steering device 7 calculates the rear wheel steering angle characteristics relative to the front wheel steering angle as shown in FIG. It has a function of issuing a control signal to variably control the rotational position of the guide plate 16 so as to vary it in accordance with the vehicle speed.

Next, the operation of the above embodiment will be explained.
When steering the rear wheels 8, 8 in a direction opposite to the steering direction of the front wheels 2, 2 accompanying the steering operation to make the steering positions of the front and rear wheels 2, 8 in opposite phases,
The rear wheel steering device 7 is operated by the operation of the controller 27.
By rotating the motor 24 (actuator), the guide plate 16 is moved to the first rod member 1.
0 in the clockwise direction when viewed from above by an angle α smaller than 90 degrees to obtain an opposite phase position A. In this state, for example, when the front wheels 2, 2 are steered to the right, the first rod member 10 moves forward, the second rod member 11 moves to the left, and the rear wheels 8, 8 move to the left. Be steered. On the other hand, when the front wheels 2, 2 are steered to the left, the first
The rod member 10 is moved rearward, and the second rod member 11 is moved rightward, so that the rear wheels 8, 8 are steered rightward, so that the steering phases of the front and rear wheels 2, 8 are in opposite phases. Become.

At that time, the guide plate 16 is connected to the first rod member 1.
By changing the angle α with respect to 0, the ratio of the moving distance of the second rod member 11 to the first rod member 10 changes, thereby causing the front wheels 2, 2
The ratio of the steering angle of the rear wheels 8, 8 to the steering angle of the rear wheels 8, 8, that is, the steering ratio changes.

On the other hand, when the steering direction of the rear wheels 8, 8 is steered in the same direction as the steering direction of the front wheels 2, 2 to make the steering phases of the front and rear wheels 2, 8 the same, the guide plate 16 to the first rod member 10 at an angle α smaller than 90° in the counterclockwise direction when viewed from above.
But hold it and rotate it to the same phase position B. In this state, the second rod member 11 is connected to the first rod member 10.
The front and rear wheels 2 and 8 move in the opposite direction to the movement of
are steered in the same direction and form the same phase.

At that time, if the angle α between the guide plate 16 and the first rod member 10 is changed, both rod members 10,
The steering ratio of the front and rear wheels 2 and 8 changes as the ratio of the moving distances of the wheels 11 changes, as in the case of the opposite phase described above.

Further, when the rear wheels 8, 8 are stopped regardless of the steering of the front wheels 2, 2 and the steering phase of the front and rear wheels 2, 8 is set to zero phase, the guide plate 16 is connected to the first rod member 10. When rotated to the parallel zero phase position C, in that state, even if the first rod member 10 moves back and forth, the second rod member 11 does not move, and this changes the steering phase of the front and rear wheels 2 and 8. becomes zero phase, and accordingly, the steering ratio also becomes zero.

Therefore, the rotational position of the guide plate 16 changes due to the operation of the motor 24, and the guide plate 16 moves to the first position.
As the angle α with the rod member 10 changes, the steering phase and steering ratio of the front and rear wheels 2, 8 change, so the controller 27 controls the operation of the motor 24, and the rotational position of the guide plate 16 is adjusted according to the vehicle speed. If controlled, the steering phase and steering ratio of the front and rear wheels 2 and 8 can be variably controlled according to the vehicle speed, and it is therefore possible to obtain the rear wheel steering angle characteristics relative to the front wheel steering angle as shown in FIG. can.

Further, since the front and rear wheels 2, 8 are mechanically connected via the first rod member 10, the guide plate 16, and the second rod member 11, the rear wheels 8, 8 can be connected to the front wheels 2, 2 with a simple structure. The steering system can be steered by following the current flow, resulting in improved operational reliability compared to conventional hydraulic systems.

In the above embodiment, the guide groove 1 of the guide plate 16
As the connecting pin member 18 that is slidably fitted to the connecting pin member 6a, a roller unit type as shown in FIG. 3 is used, but it may be changed to a tapered roller type as shown in FIG. .

That is, in FIG. 5, the guide groove 16'a of the guide plate 16 is formed to have a tapered cross section.
On the other hand, the linking pin member 18' attached to the second rod member 11 has a shaft portion 30 rotatably supported by the second rod member 11 via a bearing 19.
and a taper roller 31 which is slidably supported on the shaft portion 30 and slidably and rollably fitted into the guide groove 16'a, and the taper roller 31.
A spring 32 urges the guide groove 16'a to press against the wall surface of the guide groove 16'a. and,
As the first rod member 10 moves, the guide plate 16
When the rod moves, the tapered roller 31 of the linking pin member 18' slides while rolling in the guide groove 16'a, so that the driving force of the first rod member 10 is transmitted to the second rod member 11. ing.

Therefore, in this case, there is an advantage that the structure of the linking pin member 18' is simplified, but in terms of allowing the linking pin member to run stably within the guide groove, the roller unit type as in the above embodiment is preferable. It is more preferable to adopt it.

FIG. 6 shows a second embodiment (the same parts as in FIG. 2 are denoted by the same reference numerals and a detailed explanation thereof is omitted), in which the above-mentioned first embodiment is used as an actuator for rotating the guide plate 16. A hydraulic cylinder is used instead of the motor 24 as in the embodiment.

That is, in this embodiment, a lever member 33 is attached to the upper end of the support shaft 17 that supports the guide plate 16 on the base plate 15 (first rod member 10), and the lever member 33 is attached to the rotational end of the lever member 33 on the base plate 15. A piston rod 34a of a hydraulic cylinder 34 attached to the piston rod 34a is connected to the piston rod 34a. Although not shown, the two hydraulic chambers 34c, 34c defined by the piston 34b of the hydraulic cylinder 34 are connected to an electromagnetic control valve that switches and controls the supply of pressure oil from the oil pump, and the control valve is connected to a controller. The output of is connected and
By controlling the operation of the control valve, the hydraulic cylinder 34 is operated to expand and contract, and the guide plate 16 is
It is designed to be rotated. The hydraulic chambers 34c, 34c of the hydraulic cylinder 34 are equipped with springs 35, 35 having the same spring force, respectively, and urge the piston 34b to the neutral position of its stroke, thereby pushing the guide plate 16. is rotated and biased to a zero phase position (a position overlapping with the first rod member 10). The rest of the structure is the same as that of the first embodiment. Therefore, this embodiment can also achieve the same effects as the first embodiment.

It goes without saying that various actuators for rotating the guide plate 16 can be used other than the motor 24 and hydraulic cylinder 34 used in each of the above embodiments.

FIG. 7 shows a third embodiment (the same parts as in FIG. 2 are denoted by the same reference numerals and detailed explanation thereof is omitted), in which the guide plate 16 is connected remotely from the outside of the case 9 by a link mechanism. It is designed to be operated.

That is, in FIG. 7, 36 is a bracket attached to the inner lower surface of the case 9 so as to straddle the second rod member 11, and 37 is supported by the bracket 36 and the upper wall of the case 9, and is supported by the upper wall of the case 9.
A rotating shaft 38 that is rotatably driven by an actuator (not shown) provided on the outer surface is a rotating arm whose central portion is integrally fixed to the rotating shaft 37, and each rotation of the rotating arm 38 The movable ends are connected to each rotary end of the guide plate 16 via links 39, 39 which are parallel to each other and have the same length, and the rotary arm 38, the guide plate 16 and the link 39,
39 constitutes a parallel link mechanism 40. Further, a bearing hole 1 provided in the base plate 15 for supporting a support shaft 17 for supporting the guide plate 16 is provided.
5a is formed as a long hole extending in the left-right direction,
The locus of movement of the guide plate 16 in the longitudinal direction is corrected in accordance with the regulation by the parallel link mechanism 40.

Therefore, in this embodiment, the parallel link mechanism 40 is linked by an actuator provided outside the case 9 to remotely control the guide plate 16, so the space inside the case 9 is reduced compared to the above two embodiments. It has excellent advantages such as being small and making maintenance and inspection of the actuator easy.

In each of the embodiments described above, the guide grooves 16a and 16'a of the guide plate 16 are linear, and the front wheel steering angle is adjusted by rotating the guide plate 16 according to the front wheel steering angle and the vehicle speed. However, the guide groove is set in advance in a shape that corresponds to the basic characteristics of the rear wheel steering angle relative to the front wheel steering angle, and the guide plate is rotated only according to the vehicle speed. The above basic characteristics may be changed to be corrected by operation.

Furthermore, in each of the above embodiments, the first rod member 10
The guide plate 16 is supported on the C base plate 15), and the linking pin member 18, which is fitted into the guide grooves 16a, 16'a of the guide plate 16, is attached to the second rod member 11.
18', but conversely, the first rod member 10
Connecting pin members 18, 18' may be attached to the second rod member 11, and the guide plate 16 may be supported by the second rod member 11.
The same effects as those of each embodiment can be achieved.

(Effects of the Invention) As explained above, according to the four-wheel steering device for a vehicle of the present invention, two rod members are connected to the front and rear wheels and are slidable in the axial direction substantially perpendicular to each other. A guide plate is rotatably supported on one side, and a linking pin member that is fitted and guided in the guide groove of the guide plate is attached to the other side, and the guide plate is rotated by an actuator to connect both rod members. By changing the relative moving direction and moving distance ratio, and changing the steering phase and steering ratio of the front and rear wheels, the structure is simple and highly reliable due to the mechanical connection of the front and rear wheels. But then,
It is possible to change and control the rear wheel turning angle characteristics with respect to the front wheel turning angle according to the vehicle speed.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIGS. 1 to 5 show the first embodiment, FIG. 1 is an overall schematic configuration diagram, and FIG. 2 is an enlarged sectional view of the main parts of the rear wheel steering device. , FIG. 3 is an enlarged sectional view of the linking pin member, FIG. 4 is an explanatory diagram showing an example of rear wheel steering angle characteristics with respect to the front wheel steering angle, and FIG. 5 is equivalent to FIG. 3 showing a modification of the linking pin member. 6 is a diagram equivalent to FIG. 2 showing the second embodiment, and FIG. 7 is a diagram equivalent to FIG. 2 showing the third embodiment. 1...Steering device, 2...Front wheel, 7,
7', 7''... Rear wheel steering device, 8... Rear wheel, 9...
Case, 10... First rod member (front wheel side rod member), 11... Second rod member (rear wheel side rod member), 16... Guide plate, 16a, 16'a...
Guide groove, 18, 18'... Linking pin member, 24...
...Motor, 27...Controller, 34...Hydraulic cylinder, 40...Parallel link mechanism.

Claims (1)

[Claims] 1. A steering device for steering front wheels, a rear wheel steering device for steering rear wheels, and a controller for controlling the rear wheel steering device, the rear wheel steering device including a case, Two rod members on the front wheel side and the rear wheel side that are substantially perpendicular to each other and supported by the case so as to be slidable in the axial direction and connected to the front and rear wheels, respectively, and one of the two rod members. A guide plate is rotatably supported by a member and has a guide groove, and the rod member is attached to the other rod member and is slidably fitted into the guide groove of the guide plate, and when the front wheel side rod member moves in the axial direction. The linking pin member that slides in the guide groove of the guide plate and the guide plate are rotated within a predetermined angle range to change the deflection angle of the guide groove with the front wheel rod member, thereby changing the axial direction of the front wheel rod member. and an actuator that changes the relative movement direction and amount of movement in the axial direction of the rear wheel side rod member with respect to the movement, and the controller also controls the actuator of the rear wheel steering device to control the rear wheel rotation with respect to the front wheel steering angle. A four-wheel steering system for a vehicle, characterized in that it emits a control signal that variably controls the rotational position of the guide plate so as to change steering angle characteristics.