JPH08300924A - Four-wheel steerable rear-wheel suspension system - Google Patents

Abstract

PURPOSE: To provide a four-wheel steering device simple in structure and capable of being manufactured at a low cost by providing hydraulic bushing means connecting a sub frame to a body and controlling the supply and return of a hydraulic pressure according to a vehicle speed an steering wheel angle so as to perform the steering of rear wheels. CONSTITUTION: Projected parts 3 and 3' projecting upward from an intermediate part are provided at both ends of a body so as to install a sub frame 1 on the bottom surface of the body, and a steering knuckle rotatably supporting a wheel through a pair of front and rear control links is connected to the lower part of each of the projected parts 3 and 3'. Also, hydraulic bushings 7 and 7' receiving a hydraulic pressure to vary its shape are installed at the upper part of each of the projected parts 3 and 3'. The bushings 7 and 7' comprise inside tubes 71 and 71', outside tubes 73 and 73', and elastic members 75 and 75' provided between them, respectively. Then, the supply and drainage of fluid to front and rear variable fluid chambers 77, 79 and 77', 79' formed in the elastic members 75 and 75' are controlled by a solenoid valve 11 according to a vehicle speed and a steering wheel angle so as to perform the steering of rear wheels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel suspension system capable of steering a rear wheel, and more particularly to a rear wheel suspension system capable of controlling a steering direction of a rear wheel according to a steering direction and speed of a vehicle.

[0002]

2. Description of the Prior Art Generally, a steering device in a vehicle should provide ease of operation, good steering and safety as a means to allow the driver to control the position of the front wheels. This is closely related to the suspension system. However, since a steering device that controls only the position of the front wheels tends to turn while the rear wheels are pulled by the vehicle body when traveling on a curve,
When steering at high speeds, the center of the vehicle body suddenly shifts and becomes unstable, which is a major factor causing uneven wear of tires in the long term. Further, at low speeds, since steering is performed only by the front wheels, there is a problem that the turning radius cannot be sufficiently reduced.

Various four-wheel steering systems have been proposed in order to solve the problems of such steering systems. Normal,
In the conventional four-wheel steering device, the steering input applied when the driver operates the steering wheel is simultaneously transmitted to the front and rear wheels, so that the rear wheels have the same steering angle as the front wheels by the rear wheel steering device. The steering system is designed so that the front and rear wheels are equipped with actuators, and the control unit supplies hydraulic pressure to the front and rear wheel actuators according to the vehicle speed to control the rear wheels. It is classified into an electronic control method and a method of controlling.

[0004]

However, the above-described four-wheel steering device has a complicated connecting structure with the front wheels because the rear wheels are steered in association with the steering of the front wheels. Therefore, there are problems such as a decrease in the productivity of the steering device, an increase in manufacturing cost, and the complexity of maintenance.

The present invention has been devised in order to solve the problems of the above-described conventional steering device. After the rear wheels can be steered independently of the front wheels. Its purpose is to provide a wheel suspension. Another object of the present invention is to provide a four-wheel steering device having a simple structure and a low manufacturing cost.

[0006]

In order to achieve the above object, the present invention provides a steering knuckle for rotatably supporting a wheel in a vehicle having front, rear, left and right directions, and a steering knuckle attached to a lower portion of a vehicle body. A subframe, a plurality of links connecting the subframe and a steering knuckle, and the subframe for connecting the subframe to a vehicle body.
Hydraulic bushing means formed on the left and right of the engine, and connected to the hydraulic bushing to supply hydraulic pressure to the hydraulic bushing means according to the speed and steering direction of the vehicle to control the steering of the rear wheels. Provided is a rear wheel suspension device including a hydraulic pressure control means and capable of steering a rear wheel.

The fluid pressure control means includes a fluid storage tank for storing fluid, a fluid pressure pump, and a solenoid valve which receives fluid pressure from the fluid pressure pump and selectively supplies the fluid pressure to the fluid pressure bushing. And an electronic control unit that appropriately controls the solenoid valve according to the traveling speed and the steering angle of the vehicle to control the hydraulic pressure supply direction.

The hydraulic bushing means according to one aspect of the present invention includes first and second elastic bushings formed on left and right mounting portions of the subframe, and the first elastic bushing is formed by a first hydraulic line. A front variable fluid chamber connected to the solenoid valve and a rear variable fluid chamber connected to the solenoid valve by a second hydraulic pressure line, wherein the second elastic bushing is connected by the first hydraulic pressure line. It includes a rear variable fluid chamber connected to the solenoid valve and a front variable fluid chamber connected to the solenoid valve via the second hydraulic pressure line.

In each of the hydraulic bushing means according to another aspect of the present invention, first and second elastic bushings are formed on the right side mounting portion of the subframe in the front and rear, and on the right side mounting portion of the subframe. Third and fourth formed before and after
An elastic bushing, wherein the first elastic bushing is a front variable fluid chamber connected to the solenoid valve by a first hydraulic pressure line and a rear variable fluid chamber connected to the solenoid valve by a second hydraulic pressure line. The second elastic bushing is connected to the solenoid valve via the first hydraulic line and the rear variable fluid is connected to the solenoid valve via a second hydraulic line. The third elastic bushing is connected to the solenoid valve via the second hydraulic line and the rear variable fluid chamber is connected to the solenoid valve via the first hydraulic line. A fluid chamber and the fourth elastic bushing is connected to the solenoid valve by the second hydraulic line. By the the body chamber first fluid pressure line and a variable fluid chamber after being connected to the solenoid valve.

The solenoid valve is capable of forming a hydraulic line so that the steering direction of the rear wheels is in a phase opposite to that of the front wheels when the vehicle is traveling below a certain speed, and when the vehicle is traveling above a certain speed. Is controlled by the electronic control unit so that hydraulic pressure can be supplied by the elastic bushing so that the steering directions of the rear wheels are in phase.

[0011]

【Example】

(Embodiment 1) Hereinafter, a preferred embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing a structure of a rear frame on a rear wheel side according to an embodiment of the present invention, and is a perspective view showing a state of the subframe when a vehicle is straight ahead. As shown in Figure 1,
In order to mount the sub-frame 1 on the bottom surface of the vehicle body, both ends of the sub-frame 1 have projecting portions 3 and 3'projecting upward. The lower portion of each of the protrusions 3 and 3'is connected to a steering knuckle (not shown) that rotatably supports the wheel by a plurality of control links 5. Each of the protrusions 3 and 3'is provided with a hydraulic bushing 7 and 7'having a shape which is changed by receiving a hydraulic pressure to mount the sub-frame 1 on a vehicle body.

The hydraulic bushings 7, 7'of the sub-frame 1 and the hydraulic circuit diagram for supplying hydraulic pressure thereto according to the first embodiment of the present invention will be described in more detail with reference to FIG.

As described above, the bushings 7, 7'for connecting the subframe to the bottom surface of the vehicle body are interposed between the both side mounting protrusions 3, 3'of the subframe. Each of the bushings 7, 7'includes an inner tube 71, 71 'and an outer tube 73,
73 'and elastic members 75, 75' inserted between them. The elastic members 75, 75 ′ are provided with variable fluid chambers 77, 79, 7 in the longitudinal direction of the vehicle body, respectively.
7'and 79 'are formed. Each of the variable fluid chambers is connected to a solenoid valve 11 by hydraulic lines 9 and 9 ', and the solenoid valve 11 is connected to a hydraulic pump 13 for supplying a fluid and a storage tank 15 for storing the fluid. It is controlled by an electronic control unit ECU that senses and controls the speed of the vehicle and the steering angle of the steering wheel.

FIG. 2 is a view showing a state in which the hydraulic pressure when the vehicle is straight ahead is uniformly supplied to all variable fluid chambers and the rear wheels are not steered. Reference numeral X indicates when the vehicle is straight ahead. The axis line of the subframe is shown.

The front variable fluid chamber 77 formed in the elastic member 75 of the bushing 7 is connected to the solenoid valve 11 through the branch line 91 of the hydraulic pressure line 9, and the elastic member of the bushing 7 '. The rear variable fluid chamber 79 ′ formed in 75 ′ is connected to the solenoid valve 11 through a branch line 93 of the hydraulic line 9. Further, the rear variable fluid chamber 79 formed in the elastic member 75 of the bushing 7 is connected to the solenoid valve 11 through the branch line 91 ′ of the hydraulic line 9 ′, so that the elasticity of the bushing 7 ′ is increased. The front variable fluid chamber 77 'formed in the member 75' is connected to the solenoid valve 11 through a branch line 93 'of the hydraulic pressure 9'.

As described above, the four-wheel steerable rear wheel suspension system according to the first embodiment of the present invention will be described with reference to FIGS. 3 and 4.

FIG. 3 is a drawing showing the rear wheel side sub-frame when rotating to the right at a speed lower than the reference speed, and the front and rear wheels 2, 2 ', 4, 4', so as to increase the steering angle at low speed running. It is preferable that the wheels of (1) and (2) have opposite phases. Therefore, the solenoid valve controlled by the electronic control unit according to the signals input from the steering angle sensor S1 and the vehicle speed sensor S2 makes the line 9 communicate with the hydraulic pump 13 and the line 9 ′.
The hydraulic pressure is supplied to the line 9 by communicating with the storage tank 15, and the hydraulic pressure is formed on the elastic members 75 and 75 'of the bushings 7 and 7'through the branch lines 91 and 93, respectively. The rear and front variable fluid chambers 79, 77 'are supplied to expand the fluid chambers.

At the same time, the fluid supplied into the front and rear variable fluid chambers 77 and 79 'formed in the elastic members 75 and 75', respectively, flows through the branch lines 91 'and 93'. It is discharged to the storage tank 15 through 9 ', and each variable fluid chamber 77, 79' is contracted. as a result,
The left side mounting portion 3 of the subframe moves to the front side, the right side mounting portion 3'moves to the rear side, and the axis of the subframe moves in the X-direction when traveling straight.
To move to X ', the left and right front wheels 4, 4'connected to the subframe 1 by the respective links face left.

FIG. 4 is a diagram showing the rear wheel side subframe when the vehicle is rotating to the right at a reference speed or higher. When the vehicle is running at high speed, front and rear wheels 2, 2 ', 4, 4'are provided for steering safety. It is preferable that the wheels have the same phase. Therefore, the solenoid valve controlled by the electronic control unit according to the signals input from the steering angle sensor S1 and the vehicle speed sensor S2 allows the line 9'to communicate with the hydraulic pump 13 and the line 9 to the storage tank 15 so as to communicate with the line. Hydraulic pressure is supplied to 9 ', and this hydraulic pressure is applied to each branch line 91', 93 '.
Through which the fluid is supplied to front and rear variable fluid chambers 77 and 79 'formed in the elastic members 75 and 75' of the bushings 7 and 7 ', respectively, to expand the fluid chambers.

At the same time, the fluid supplied to the rear and front variable fluid chambers 79 and 77 'formed on the elastic members 75 and 75', respectively, flows to the line 9 via the respective branch lines 91 and 93. Along the storage tank 15, the variable fluid chambers 79 and 77 'are contracted. As a result, the left-side mounting portion 3 of the subframe moves to the rear side, the right-side mounting portion 3'moves to the front side, and the shaft of the subframe moves from X to X'when traveling straight, and each of the links causes The left and right front wheels 4, 4'connected to the subframe 1 face to the right.

(Embodiment 2) FIG. 5 is a diagram showing a rear wheel suspension system capable of steering four wheels according to a second embodiment of the present invention. The same numbering system is used for the same parts as those in the above figures. I took it.

A subframe of the rear wheel suspension system according to this embodiment.
The frame 1 is the same as the above-described embodiment except that two mounting bushings are provided on each of the left and right mounting protrusions 3 and 3'of the subframe.

That is, mounting hydraulic bushings 4 and 6 are provided on the left side protruding portion 3 of the subframe in front of and behind it. The structure of each hydraulic bushing 4, 6 is the same as that of the above-described embodiment, and the hydraulic bushing 6 has a front variable fluid chamber 6 connected to the solenoid valve 11 by a line 9.
2 and a rear variable fluid chamber 61 connected to the solenoid valve 11 by a line 9 '. Also,
Also in the hydraulic bushing 4, a front variable fluid chamber 42 connected to the solenoid valve 11 by a line 9 and a rear variable fluid chamber 41 connected to the solenoid valve 11 by a line 9 ′.
And are provided.

The solenoid valve 11 is connected to the hydraulic bushing 6'of the right mounting protrusion 3'by a line 9 '.
A front variable fluid chamber 62 ′ connected to the solenoid valve 11 and a rear variable fluid chamber 6 connected to the solenoid valve 11 by a line 9.
1'is provided. The hydraulic bushing 4'is also provided with a front variable fluid chamber 42 'connected to the solenoid valve 11 by a line 9', and a rear variable fluid chamber 41 'connected to the solenoid valve 11 by a line 9. .

Therefore, for example, when the vehicle rotates rightward at the reference speed or more, the electronic control unit ECU receives signals from the steering angle sensor S1 and the vehicle speed sensor S2 to control the solenoid valve 11 to control the line 9 to the hydraulic pump. Thirteen
The line 9 ′ is connected to the storage tank 15. As a result, the fluid pressurized by the pump passes through the branch lines 90 and 92 of the line 9 to the respective hydraulic bushings 6 and 4.
Is supplied to the variable fluid chambers 62 and 42 formed in the hydraulic fluid chambers 62 and 42 to expand the fluid chambers, and the variable fluid chambers 61 ′ formed in the hydraulic bushings 6 ′ and 4 ′ along the branch lines 94 and 96 of the line 9. , 41 'to inflate this fluid chamber.

On the other hand, the storage tank 15 is provided along the branch lines 90 'and 92' of the lines 9'supplied to the variable fluid chambers 61 and 41 formed in the hydraulic bushings 6 and 4, respectively.
The fluid discharged to the variable fluid chambers 62 ′ and 42 ′ formed in the hydraulic bushings 6 ′ and 4 ′ is discharged along the branch lines 94 ′ and 96 ′ along the line 9 ′.
Is discharged to the storage tank 15 via. Therefore, the left bushing expands all the variable fluid chambers on the front side, the hydraulic bushing on the right expands all the variable fluid chambers on the rear side, and the subframe 1 rotates clockwise in the plane of FIG. The rear wheel connected to this with a link faces right.

As described above, the rear wheel suspension system according to the second embodiment is complicated in its structure by the rear wheel suspension system according to the first embodiment, but two hydraulic pressures are provided on each of the left and right sides of the subframe. Since the bushing is provided, it has an advantage that it is more effective in operation reliability.

[0029]

As described above, according to the present invention, the rear wheels can be steered independently of the front wheels by using the rear wheel suspension device having a simple structure and low manufacturing cost.

[Brief description of drawings]

FIG. 1 is a rear wheel side subframe according to a first embodiment of the present invention.
FIG.

FIG. 2 is a diagram showing a state in which the hydraulic pressure during straight traveling is uniformly supplied to all variable fluid chambers and the rear wheels are not steered according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a rear wheel side sub-frame when rotating to the right at a speed equal to or lower than a reference speed according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a rear wheel side sub-frame when rotating to the right at a reference speed or more according to the first embodiment of the present invention.

FIG. 5 is a view showing a rear wheel suspension device capable of steering four wheels according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Subframe 3,3 'Mounting protrusion 4,4', 6,6 'Mounting hydraulic bushing 9,9' Hydraulic line 11 Solenoid valve 13 Hydraulic pump 15 Storage tank S1 Steering angle sensor S2 Vehicle speed sensor ECU Electronic control unit

[Procedure amendment]

[Submission date] August 4, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 5

[Correction method] Change

[Correction content]

Claims (5)

[Claims] 1. In a vehicle having front, rear, left and right directions, a steering knuckle that rotatably supports a wheel, a subframe attached to a lower portion of a vehicle body, the subframe and the steering knuckle. A plurality of links to be connected, a hydraulic bushing means formed on the left and right of the subframe for connecting the subframe to a vehicle body, and a vehicle speed and steering direction connected to the hydraulic bushing. And a hydraulic pressure control means for controlling the steering of the rear wheels by supplying hydraulic pressure to the hydraulic bushing means in accordance with the above. 2. The fluid pressure control means receives a fluid pressure from a fluid storage tank for storing a fluid, a fluid pressure pump, and the fluid pressure pump, and selectively supplies the fluid pressure to the fluid pressure bushing. The four-wheel steerable rear wheel according to claim 1, further comprising: a solenoid valve; and an electronic control unit that appropriately controls the solenoid valve according to a traveling speed and a steering angle of the vehicle to control a hydraulic pressure supply direction. Suspension system. 3. The hydraulic bushing means includes first and second elastic bushings formed on left and right mounting portions of the sub-frame, and the first elastic bushing is connected to the solenoid valve by a first hydraulic line. A front variable fluid chamber connected to the solenoid valve and a rear variable fluid chamber connected to the solenoid valve by a second hydraulic line;
The elastic bushing includes a rear variable fluid chamber connected to the solenoid valve by the first hydraulic line and a front variable fluid chamber connected to the solenoid valve by the second hydraulic line. The rear-wheel suspension device according to 2, which is capable of steering four wheels. 4. Each of the hydraulic bushing means has first and second elastic bushings formed on the right side mounting portion of the subframe in the front and rear direction, and a first and second elastic bushing formed on the right side mounting portion of the subframe in the front and rear direction. 3 and a fourth elastic bushing, wherein the first elastic bushing is connected to the solenoid valve by a first hydraulic pressure line and the front variable fluid chamber and a second hydraulic pressure line is connected to the solenoid valve. The second elastic bushing is connected to the solenoid valve by the first hydraulic line, and the second elastic bushing is connected to the solenoid valve by a second hydraulic line. A rear variable fluid chamber, wherein the third elastic bushing is connected to the solenoid valve by the second hydraulic line, and By 1 hydraulic line includes a variable fluid chamber after being connected to the solenoid valve,
The fourth elastic bushing includes a front variable fluid chamber that is connected to the solenoid valve by the second hydraulic line and a rear variable fluid chamber that is connected to the solenoid valve by the first hydraulic line. The rear wheel suspension device according to claim 2, which is capable of steering four wheels. 5. The solenoid valve is capable of forming a hydraulic line so that the steering direction of the rear wheels is in a phase opposite to that of the front wheels when the vehicle is traveling at a constant speed or lower, and the vehicle is at a constant speed or higher. A rear-wheel suspension device capable of steering four wheels controlled by the electronic control unit so that hydraulic pressure can be supplied by the elastic bushing so that the steering directions of the rear wheels are in phase during traveling.