JPH0463715A - Suspension for vehicle - Google Patents

Abstract

PURPOSE:To keep capacity enough for accumulators and prevent the racing of drive wheels by arranging the accumulators for the drive wheels, among those connected to respective cylinders on an individually independent basis, outside of the wheel houses thereof. CONSTITUTION:Suspensions, which are mounted between a body 1 and respective wheels 2 in wheel houses 3 (3FR-3RL) formed in the body 1 to house respective wheels 2, have cylinders 4 (4FR-4RL) arranged to adjust a body level corresponding to the supply and exhaust of operating liquid. To the respective cylinders 4, gas springs 5 (5FR-5RL) as accumulators are connected on an individually independent basis. A few number of both right and left gas springs 5F for front wheels are arranged in the wheel house 3FR or 3FL, while the gas springs 5R, 5L for rear wheels are arranged in a trunk room 6. These gas springs 5R, 5L for the rear wheels are formed in large capacity, and only one of them is provided for each one of cylinders 4RR, 4RL and connected to each of the cylinders 4RR, 4RL for the rear wheels via a communication pipe 7.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a suspension device for a vehicle.

(Prior art) Vehicle suspensions, generally called passive suspensions, have a damper unit consisting of a hydraulic shock absorber and a spring (generally a coil spring), and the suspension characteristics are determined by the preset characteristics of the damper unit. Set uniformly. Of course, it is also possible to make the damping force of the hydraulic shock absorber variable, but this does not significantly change the suspension characteristics.

On the other hand, recently, a system called active suspension has been proposed in which the suspension characteristics can be changed arbitrarily.In this active suspension, basically, there is a A cylinder device is installed, and the suspension characteristics are changed by controlling the supply and discharge of hydraulic fluid to the cylinder device (see Japanese Patent Application Laid-Open No. 130418/1983). By supplying and discharging fluid, suspension characteristics can be significantly changed for various posture controls such as vehicle height control, roll control, and pitch control. There are also systems in which an accumulator, such as a gas spring, is individually connected to each cylinder device in order to absorb high-frequency vibrations from the road surface.

(Problems to be Solved by the Invention) As a result of various studies aimed at putting the active suspension into practical use as described above, it has been found that racing of the drive wheels, that is, a state in which the drive wheels spin with respect to the road surface, is likely to occur. It has been found. To explain this point in detail, when roll is suppressed by attitude control, hydraulic fluid is discharged from the cylinder device so that the vehicle height on the inner wheel side of the turn is lowered, and as a result, the internal pressure of the cylinder device is reduced. When such roll suppression control is being performed, there may be a situation where attitude control such as discharging the hydraulic fluid from the cylinder device is required, such as when the drive wheel falls into a depression in the road surface. (If the hydraulic fluid is further discharged, the internal pressure of the cylinder device will drop drastically and racing will occur. In other words, the internal pressure of the cylinder device ultimately affects the contact of the wheels with the ground.) This indicates the load, but if the internal pressure of the cylinder device for the driving wheels becomes extremely small, this ground contact load will become extremely small, causing racing on the driving wheels.

It has been found that the above-mentioned racing is caused by insufficient capacity of an accumulator such as a gas spring connected to the cylinder device. In other words, gas springs are normally installed in the wheel house to correspond to the cylinder device, but their capacity is limited due to space considerations, and their preset pressure is limited in order to maintain the minimum vehicle height. As such, a fairly large pressure (minimum internal pressure of the cylinder device) is required. In this way, the fact that the minimum required pressure is large means that control in the direction of pressure reduction is subject to considerable restrictions, which makes the above-mentioned lacing more likely to occur.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a suspension system for a vehicle that controls the attitude of a vehicle body by controlling the supply and discharge of hydraulic fluid to a cylinder device provided for each wheel, and that is capable of preventing racing of the driving wheels. The purpose is to provide

(Structure, operation, and effect of the invention) In order to achieve the above object, the present invention basically has the following structure. That is, the cylinder device includes a cylinder device that is installed between the vehicle body and each wheel and adjusts the vehicle height according to the supply and discharge of hydraulic fluid, and an accumulator that is individually and independently connected to each cylinder device. In a vehicle suspension system that controls the attitude of the vehicle body by controlling the supply and discharge of hydraulic fluid to and from the vehicle, an accumulator for driving wheels among the accumulators is disposed outside the wheel house, and the accumulator and the accumulator are disposed outside the wheel house. The structure is such that the cylinder device is communicated with through a communication pipe.

In this way, in the present invention, since the accumulator for the driving wheels is placed outside the wheel house, it is possible to arrange the accumulator while ensuring sufficient capacity, and the posture of the vehicle body can be improved while preventing racing. can be controlled.

The drive wheel accumulator can be attached to a cross member of a vehicle body, or placed in an engine room or a trunk room, for example.

(Example) Examples of the present invention will be described below based on the attached drawings. In addition, the code 17"J used with numbers in the following explanation is for the front wheel, rR" is for the rear wheel, IFRJ is for the right front wheel, rFLJ is for the left front width, rRRJ is for the right rear wheel, and rRL is for the right front wheel.
J means for the left rear wheel, and therefore, when there is no need to particularly distinguish between them, the description will be made without using these identification symbols.

In FIG. 1, 1 is a vehicle body, and 2 (2FR to 2RL) are wheels. In the embodiment, a front wheel 2FR12FL is a driven wheel, and a rear wheel 2RR12RL is a drive shaft.

Cylinder devices 4 (4FR to 4RL) are disposed in wheel houses 3 (3FR to 3RL) formed on the vehicle body 1 that house the wheels 2, respectively. Each cylinder device 4 is installed between the vehicle body 1 and the wheels 2, and adjusts the vehicle height according to the supply and discharge of hydraulic fluid.

A gas spring 5 as an accumulator is individually connected to each cylinder device 4, and the one for the front wheels is shown as 5F, and the one for the rear wheels is shown as 5R.

The front wheel gas springs 5F are arranged in the wheel houses 3FR and 3FL, respectively, on both the left and right sides. That is, as the gas springs 5F for the left and right m1 wheels, a plurality of elongated and small capacity gas springs (three in the embodiment) are used, and the corresponding cylinder devices 4FR or 4 are used.
It is arranged around the outer periphery of FL. Note that the plurality of gas valves 5F are connected to one cylinder device 4FR or 4FL so as to be parallel to each other.

In this way, i′i1 wheel 2FR12FI as the driven wheel
- gas spring 5F for wheel house 3FR13F L
This arrangement was made because it was taken into consideration that the interlocking wheel house 3FR13FL for steering width has a fairly large capacity, and that there would be no racing problem with the driven wheels.

On the other hand, the gas springs 5R15L for the rear wheels are
It is arranged in a trunk room 6 formed at the rear of the vehicle. Each of the rear wheel gas springs 5R15L has a large capacity, and only one is provided for each cylinder device 4RR, 4RL. The left and right rear wheel cylinder devices 4RR14RL are connected via communication pipes 7, respectively.

The details of the cylinder device for the 111th wheel will be explained with reference to FIG. 2, which shows the left front wheel. First, a wheel support member 1j is held by the vehicle body 1 (cross member 13 thereof) via a lower arm I2 so as to be swingable in the upward F direction, and a front wheel 2FL is attached to this wheel support member 1j.
is held rotatably. A cylinder device 4F is installed between the wheel support member 11 and the m-plane of the wheel house 3FL.
L is installed. More specifically, the cylinder device 4
The cylinder 4a of the FL is fixed to the wheel support member via the bracket 14, and the piston rod 4b of the cylinder device 4FL is fixed to the wheel house 3F via the bearing mechanism 15.
It is attached to the top of L.

A passage 4d formed in the piston rod 4b is opened to the liquid chamber 4c formed in the cylinder 4a, and the liquid chamber 4c is operated through a connection socket 16 attached to the piston rod 4b. Liquid is supplied and discharged.

A bracket 17 is fixed to the piston rod 4b outside the cylinder 4a. The upper part of a gas valve 5F, which is arranged close to and substantially parallel to the cylinder device 4FL, is fixed to this bracket 17. The interior of the gas spring 5F is defined by the free piston 5a into a gas chamber 5b and a liquid chamber 5C. The inner passage 4d is therefore always in communication with the liquid chamber 4c of the cylinder device 4FL.

An orifice 18 for generating a damping force is formed in the passage 17a within the bracket 7.

Note that 19 in FIG. 2 is a vehicle height sensor.

FIG. 3 shows details of the cylinder device for the rear wheel, and FIG. 3 shows the cylinder device for the left rear wheel. The one in FIG. 3 is basically the same as the one in FIG. 2, but the arrangement of the gas springs 5R is different. That is, the gas spring 5R is attached to the cross member 21 arranged at the rear of the vehicle body, and the gas spring 5R is attached to the communication pipe 22.
It is communicated with a passage 17a in the bracket 17 via a pipe (corresponding to the communication pipe 7 in FIG. 2). In addition, 23 in FIG. 3 is a drive shaft.

Here, the supply and discharge of hydraulic fluid to and from each cylinder device 1 is performed by a vehicle height sensor 19 that detects the vehicle height at least at each wheel position.
Based on the output from the controller, the actual posture of the vehicle body 1 is controlled to be a predetermined posture. At this time, since the capacity of the gas spring 5R for the rear wheel serving as the driving wheel is ensured to be sufficiently large, racing is reliably prevented from occurring in the rear wheel 4RR14RL serving as the driving wheel. That is, the pressure in the liquid chamber 4c in the cylinder device 4RR14RL is prevented from dropping significantly even when the hydraulic fluid is discharged therefrom (pressure fluctuations caused by supplying and discharging the hydraulic fluid are small).

Although the embodiment has been described above, the gas spring for the driving wheels may be arranged in the engine room 30 (especially in the case of a front wheel drive vehicle). Further, the gas spring for the driven wheel cylinder device may also be provided outside the wheel house similarly to the gas spring for the driving wheel cylinder device.

[Brief explanation of drawings]

FIG. 1 shows one embodiment of the present invention, and is a simplified plan view showing a case where a rear wheel accumulator as a driving wheel is arranged in a trunk room. FIG. 2 is a front partial sectional view showing the arrangement of a cylinder device for a front wheel as a driven wheel and its accumulator. FIG. 3 is a front partial sectional view showing the arrangement of a cylinder device for a rear wheel serving as a driving wheel and its accumulator. 1: Vehicle body 2FR, 2FL: Front wheels (driven wheels) 2RR, 2RL: Rear wheels (driving wheels) 3FR to 3RL: Wheel houses 4FR to 4FL Niji cylinder device 5F = Gas spring (for front wheels) 5R: Gas spring (for rear wheels) 6: Trunk room 7: Communication pipe 21: Cross member 22: Communication pipe 30: Engine room diagram

Claims (3)

[Claims] (1) A cylinder device installed between the vehicle body and each wheel to adjust the vehicle height according to supply and discharge of hydraulic fluid, and an accumulator connected to each cylinder device individually,
In a vehicle suspension device that controls the attitude of a vehicle body by controlling the supply and discharge of hydraulic fluid to the cylinder device, an accumulator for a drive wheel among the accumulators is disposed outside the wheel house, A suspension device for a vehicle, characterized in that the accumulator and the cylinder device are communicated with each other via a communication pipe. (2) Claim 1, wherein the drive wheel accumulator is attached to a cross member of a vehicle body. (3) Claim 1, wherein the drive wheel accumulator is disposed in an engine room or a trunk room.