JPH03186482A - Rear wheel steering device for vehicle - Google Patents

Abstract

PURPOSE:To stabilize running by fixing a leaf spring on the failure side at the position when a failure occurs, and fixing a leaf spring on the normal side at the position to set rear wheels to the non-steering state when one of a pair of the right and left actuators fails in a rear wheel steering device with leaf springs. CONSTITUTION:When a hydraulic cylinder 38L or a hydraulic pump 46L driving a leaf spring 30L on the left side during running, for example, a control unit 50 presses the plate body 65 of a stopper 58 to the piston 41 of the hydraulic cylinder 38L via a stopper drive motor 66 fitted to the hydraulic cylinder 38L to fix the position of the piston 41. The position of the plate body 65 of the stopper 58 of a hydraulic cylinder 38R on the right side is moved until it becomes the same as the position of the stopper 58 on the left side, and the stopper 58 is fixed at this position. The control unit 50 then opens a normally- opened electromagnetic switch valve 61. Running stability can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rear wheel steering device for a vehicle having left and right rear wheels supporting a common axle member attached to both ends thereof and a leaf spring.

(Prior Art) A suspension system for a vehicle proposed by the present applicant and disclosed in Japanese Patent Application Laid-open No. 63-212109 has front and rear ends supported by shackle members rotatably attached to the vehicle body frame. Equipped with a pair of left and right double shackle leaf springs that are arranged to be movable in the front and rear directions, and these pair of left and right leaf springs are moved in the front and rear directions in opposite directions by a pair of left and right actuators as the front wheels are steered. As a result, the rear wheels are steered in the opposite phase or in the same phase as the front wheels, improving turning performance when the vehicle is running at low speeds and driving stability when driving at high speeds. ing.

By the way, in a vehicle equipped with such a rear wheel steering device, if any one of the pair of left and right actuators fails, running stability may be impaired and an unexpected situation may occur.

(Object of the Invention) Therefore, an object of the present invention is to provide a rear wheel steering device having a fail-safe function that ensures running stability of a vehicle in the event of an actuator failure.

(Structure of the Invention) In the vehicle rear wheel steering system according to the present invention, when one of the pair of left and right actuators fails, the leaf spring on the failed side is fixed at the position at the time of failure, and the leaf spring on the normal side is fixed. The present invention is characterized in that a control means is provided for driving an actuator to move the leaf spring on the normal side to a position where the rear wheels are not steered, and for fixing it at that position.

(Effects of the Invention) According to the present invention, the running stability of the vehicle can be ensured even when the actuator fails without using any special means.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram schematically showing an embodiment of a rear wheel steering device for a vehicle according to the present invention, together with a front wheel steering mechanism for an automobile in which the device is used. In Fig. 1, left and right front wheels 2L,
A front wheel steering mechanism 5 is provided that steers the front wheel 217.2R in response to steering by the steering wheel 3. The front wheel steering mechanism 5 includes a pair of knuckle members 6 that rotatably support the front wheel 217. A rank un1' pinion having a pair of tie rods 8 whose ends are connected to the knuckle arms 6a of the member 6, and a rack shaft 9 whose other ends are connected to both ends of the pair of tie rods 8. The steering gear mechanism 10 is comprised of a steering gear mechanism 10 of the type.

The left lj rear wheels 12L and 12R are each rotatably attached to both ends of an axle member 20 extending in the vehicle width direction to which the driving force of the propeller shaft 16 is transmitted via the differential gear device 14.

In addition, the vehicle body frame 22, whose front side is omitted and is shown in FIG.
A pair of shank members 2611.26R are rotatably attached at their upper ends by a shaft 27 fixed to the vehicle body frame 22, and the left and right portions of the vehicle body frame 22 are located in front of the positions where the shackle members 26L and 26R are attached. A pair of shackle members 28L are provided at predetermined positions.
, 28R are rotatably attached at their upper ends by a shaft 29. The rear ends of the leaf springs 30L, 30R are attached to the lower ends of the shackle members 26L, 26R, and the front ends of the leaf springs 3OL, 30R are attached to the middle part of the shackle members 28I1.28R.
The leaf springs 30L and 30R are the shackle member 2
A pair of brackets 24 fixed to the axle member 20 are disposed below the 6 leaf spring 3017.30R, which is supported movably in the longitudinal direction of the vehicle body by 7.26R28L and 28R. As is clear from FIG. 3, a through hole 32 is formed in the intermediate portion of the springs 30L and 3OR in the vertical direction. And bracket 24 and leaf spring 30L, 301'? are fastened to each other by bolts 34 and style 35 inserted into through holes 32. In addition, the axle member 20 and the leaf springs 30r, 3OR are located at positions sandwiching the napht 35 in the front and back direction on the upper surface of the leaf springs 30L, 3OR.
An elastic member 36 for preventing 0R from colliding with the vehicle body frame 22 due to vertical vibration of the rear wheels 12L and 12H.
is fixed.

Shackle members 28L, 28 in the vehicle body frame 22
A pair of hydraulic cylinders 38■1.3B+? (Brackeno)
The piston rods 40L and 40R are attached via the hydraulic cylinders 39L and 39R, and extend from the hydraulic cylinders 38L and 38R, respectively.
They are attached to the lower ends of 28T7 and 28R, respectively.

Therefore, when the piston rod 40■7.40R protrudes from the hydraulic cylinders 38L, 38R, the knot members 28L, 28R and the shackle member 26■2
．． 26R rotates about shafts 29 and 27, respectively, and thereby the leaf springs 30L and 3OR move toward the rear of the vehicle body.

In addition, the piston rods 40L and 40R are connected to the hydraulic cylinder 3.
When the leaf spring 30I4.30R is pulled into 8L and 38R, the leaf spring 30I4.30R moves toward the front side of the vehicle body.

Hydraulic nolinders 38L and 38R are piston rods 40
Hydraulic chambers 38a and 38b are respectively partitioned by pistons 41 fixed to L and 40R, and these hydraulic chambers 38a and 38b communicate with each other via an oil passage 45. The oil passage 45 includes a control unit 5.
Oil pumps 46L and 46R controlled by 0 are installed.
I'm getting fucked.

As is clear from FIG. 4 showing the configuration of one of the hydraulic cylinders 38r, the hydraulic cylinders 38L and 38R are equipped with a movable stopper 58 in one hydraulic chamber 38a, and a piston in the other hydraulic chamber 38b. The piston rod 40L is provided with a spring 6° that biases the piston rod 40L in a direction in which the piston rod 40L draws the piston rod 41 into the hydraulic cylinder 38L. In addition, the hydraulic chambers 38a, 3
8b is connected to the reservoir 6 through an oil passage 62 having a normally closed solenoid valve 61 which is controlled to open and close by the control unit 50.
It is connected to 3.

The stopper 58 includes a cylindrical body 64 that is attached to an end wall of the hydraulic cylinder 38L on the side of the hydraulic chamber 38a so as to be slidable in the moving direction of the piston 41, and is fixed to an end of the cylindrical body 64 inside the hydraulic chamber 38a. It consists of a plate body 65. 66 is a motor that drives the stopper 5, and a worm gear 67 is formed at the tip of an output shaft 66a that can rotate in both directions.

This worm gear 67 includes a worm wheel 6 provided at one end of a rotating wheel 68 inserted into the cylindrical body 64.
9 is engaged. A worm gear 70 is formed in a portion of the rotating wheel 68 that is inside the cylindrical body 64 , and
A threaded groove is formed on the inner peripheral surface of the worm gear 70 to be screwed into the worm gear 70 through a large number of steel balls 71, thereby forming a ball Nand type (recirculating ball type) gear mechanism. Therefore, when the motor 66 is driven, the stopper 58 slides depending on the rotational direction of the output shaft 66a. The stopper 58 is normally in the retracted position shown by the solid line in FIG. 4, but when the motor 66 is driven, it moves to the position shown by the dashed line in FIG. It will stop at the position where it touches.

At this time, W[the on-off valve 61 is opened and the hydraulic chambers 38a, 38
When the oil pressure in b decreases, the piston 41 is pressed against the plate 65 by the biasing force of the spring 60 and is fixed at that position. Therefore, as the piston 41 is fixed, the leaf spring 3OL connected to the piston 41 via the piston rod 40L and L7 is also fixed.

The control unit 50 includes a steering angle sensor g5 that is arranged in relation to the front wheel steering mechanism 5 and detects the steering angle θ of the front wheels 2L and 2R.
2 and a detection signal Sv from a vehicle speed sensor 54 that detects the vehicle speed based on the rotation speed of the front wheels 2L (or 2R). And the control unit 50
The oil pump 4 is operated in order to operate the hydraulic cylinders 38L and 38R based on the detection signals Sθ and SV.
6L.

Control signals Sf and Sr for 46R are output.

The oil pumps 46L and 46R are operated by, for example, the control m signal S1.
When Sr reaches a predetermined height, the hydraulic cylinder 38L
, 38R to introduce oil from the respective hydraulic chambers 38a to the hydraulic chambers 38b, and the control signal S7! , S
takes a predetermined low level, the hydraulic cylinders 38L, 3
It operates to introduce oil from each hydraulic chamber 38b of 8R to the hydraulic chamber 38a.

When the vehicle equipped with the rear wheel steering device configured in this manner is traveling, the control unit 50 controls the steering angle sensor 52 when the detected vehicle speed from the vehicle speed sensor 54 is less than a predetermined value. If the detection signal Sθ from the oil pump 46 indicates that the vehicle is turning left, the oil pump 46
A control signal SR that takes a predetermined high level is supplied to the oil pump 46R to operate it, and a control signal 3r that takes a predetermined low level is supplied to the oil pump 46R to operate it.

Therefore, hydraulic cylinder 381. Hydraulic chamber 38 in
The pressure in the hydraulic chamber 38a of the hydraulic cylinder 38R increases, and the piston rod 40L is drawn toward the hydraulic chamber 3Ba from the position shown by the broken line in FIG. , the piston rod 40R projects toward the hydraulic chamber 38b from the position indicated by the broken line in FIG. 1 against the biasing force of the spring 6. In such a state, the shackle members 28L and 26L are
The leaf spring 30L moves to the front side of the vehicle by being rotated toward the front side of the vehicle with the shaft 29.27 as the pivot, and the shackle member 28R26R is rotated around the shaft 29.27.
The leaf spring 3OR moves toward the rear of the vehicle by being rotated toward the rear of the vehicle about the support shaft. As a result, the leaf springs 3OL, 3
The axle member 20 supported by 0R rotates clockwise in FIG. 1, and the rear wheels 12L and 12R are steered in the opposite phase to the front wheels 2L and 2R, improving CJ turning performance when driving at low speeds. will improve.

Further, when the control unit receives a detection signal from the steering angle sensor 52 indicating that the steering angles of the front wheels 2L and 2R are set to zero and the vehicle has transitioned from a turning state to a straight-ahead state, , supplies a control signal SR having a low level to the oil pump 46L.

As a result, the piston rod 40L is connected to the spring 60.
At the same time, the piston rod 40R is pulled into the hydraulic cylinder 38R and returned to the position shown by the broken line in FIG. 1, so that the rear wheels 121. The steering angle of 12R is zero.

On the other hand, when the vehicle is running and the detection signal 3v from the vehicle speed sensor 54 is not high and the vehicle speed is above a predetermined value, the control unit 50 controls, for example, when the detection signal Sθ from the steering angle sensor 52 indicates that the vehicle is moving to the left. When changing lanes, a control signal Sl that takes a low level is supplied to the oil pump 46L to activate it, and a control signal Sr that takes a high level to the oil pump 46R is supplied to activate it. Activate.

Therefore, the hydraulic chamber 38 in the hydraulic cylinder 38I3
As the pressure inside a increases, the piston rod 40I7
The piston rod 40R protrudes toward the hydraulic chamber 38b from the position indicated by the broken line in FIG. It is drawn into the hydraulic chamber 38a from the position indicated by the broken line in FIG. In this state, as shown by the dashed line in FIG.
．． The leaf spring 30L moves toward the rear of the vehicle by being rotated toward the rear of the vehicle about the spindle 27. Furthermore, the leaf spring 30R moves toward the front of the vehicle by rotating the soyasokuru member 28R26R about the shaft 29.27 toward the front of the vehicle. As a result, the axle member 20 rotates counterclockwise in FIG. 1, and the rear wheels 12L12R are steered in the same phase as the front wheels 2L to 2R, improving running stability during high-speed driving. do.

The control unit 50 also controls the steering angle of the front wheels 2L and 2R when the detection signal Sθ from the steering angle sensor 52 indicates that the steering angle of the front wheels 2L and 2R has become zero and the vehicle has transitioned from a lane change state to a straight-ahead driving state. supplies the oil pump 46L with a control signal SX that increases the health of the oil pump 46L, and
A control signal Sr that takes a low level is supplied to R. As a result, the piston rod 40L is retracted into the hydraulic cylinder 38L, the piston rod 4OR is pulled out, and the pressure nozzle cylinder 38R protrudes, returning to the position shown by the broken line in FIG. The steering angle becomes zero.

Next, while driving, for example, the left leaf spring 30L
Hydraulic cylinder 38L or hydraulic pump 46L that drives
If a failure occurs, the control unit 50 senses this and supplies a drive signal to the stopper drive motor 66 attached to the hydraulic cylinder 381. As a result, the stopper 58 has a plate body 65 that is connected to the hydraulic cylinder 3.
It slides to a position where it contacts the 8L piston 41 and stops at that position. At the same time, the control unit 50 is installed on the right hydraulic cylinder 38R.

The stopper 58 is moved until the position of the plate 65 of the stopper 58 in the hydraulic cylinder 38R is equal to the position of the plate 65 of the stopper 58 in the left hydraulic cylinder 381. let me,
and stop at that position. After these operations are completed, the control unit 50 supplies a control signal Sf to the normally closed electromagnetic on-off valve 61 to open the oil passage 62. Therefore, the hydraulic chambers 38a, 38 in both hydraulic cylinders 38L, 38R
b communicates with the reservoir 63 through the oil passage 62, and the oil level drops rapidly, so the pistons 41 in the hydraulic cylinders 38L and 38R are at positions where they are pressed against the crosspiece 65 of the l-flange 58 by the springs 60, respectively. is latched to
Therefore, the left and right leaf springs 30L, 30R
are fixed in the state shown on the right side of Fig. 5, and the rear wheels 12L,
The steering angle of 12R is maintained at zero, and running stability is maintained.

In the embodiment described above, each hydraulic cylinder 38I7.381?
A stopper 58 provided at 4 is held in a position where it is in contact with the end wall on the side of the hydraulic chamber 38a in a normal state. By controlling the motor 66 such that the motor 66 is in the state shown in FIG.

Although illustrations and detailed explanations are omitted, the propeller shaft 1G is provided with a spline joint 4J that allows the length of the propeller shaft 16 to be changed. The movement of the axle member 20 in the longitudinal direction of the vehicle body due to this movement is absorbed by the spline joint.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram schematically showing an embodiment of a rear wheel steering device for a vehicle according to the present invention, together with a front wheel steering device for a vehicle to which it is applied, and FIGS. 2 and 3 show the main parts thereof. A perspective view and a side view, FIG. 4 is a sectional view showing a hydraulic cylinder equipped with a stopper and a stopper drive mechanism, and FIG. 5 is an explanatory diagram of the operation of the apparatus according to the present invention. 2L, 2R - Front wheel 12L, 12R - Rear wheel 20 Axle member 22 Body frame 26L, 26R, 2
811, 28R Shackle member 30 L, 30R Leaf spring 38I 1.38R Hydraulic cylinder 46L, 46R Oil pump 50 - Control, unit 52 - Rudder angle sensor 54 Vehicle speed sensor 58 Stopper 60 Spring 61 Normally closed electromagnetic on-off valve 63 Reservoir 6 motor

Claims (1)

[Scope of Claims] A pair of left and right double shackle leaf springs whose front and rear ends are supported by shackle members rotatably attached to the vehicle body frame and are disposed so as to be movable in the front and back direction of the vehicle, and a pair of these left and right double shackle leaf springs. In a rear wheel steering system for a vehicle, which is equipped with a pair of left and right actuators that move leaf springs in the front and rear directions in opposite phases to each other, if one of the pair of left and right actuators fails, the leaf on the failed side A control means that fixes the spring at the position at the time of failure, drives the actuator on the normal side to move the leaf spring on the normal side to a position where the rear wheels are in a non-steering state, and fixes it at that position. What is claimed is: 1. A rear wheel steering device for a vehicle, comprising: