JPH02182511A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To prevent excessive reduction in vehicle height by setting the bump limit position of a bump stopper for a ACS-provided vehicle relatively low, for users having a ACS-provided vehicle with variable suspension characteristics and a passive suspension-provided vehicle of the same model. CONSTITUTION:An ACS-provided vehicle with variable suspension characteristics is provided with a hydraulic cylinder 3 between a wheel and a body, and a gas spring 5 is connected to a hydraulic chamber 3c for the hydraulic cylinder through a connecting passage 4. The characteristics of a suspension is adjusted by controlling the supplying and delivering of fluid into and from the hydraulic cylinder 3. On the other hand, a passive suspension-provided vehicle is provided with a strut (a) comprising a shock absorber (b) and a coiled spring (c) positioned at its upper periphery. In this case, the lower surface of a bump stopper 54 for the ACS-provided vehicle approaches more closely to the upper end surface of a cylinder main body 3a than a bump stop (i) for the passive suspension-provided vehicle to set the bump limit position at lower level.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a suspension device for a vehicle, and more particularly to a suspension device that supports a vehicle body load using only fluid pressure in a fluid cylinder disposed between a vehicle body and wheels. It is related to.

(Prior Art) Conventionally, as a suspension device for a vehicle, a fluid cylinder is disposed between a vehicle body and a wheel, and a gas spring is attached to the fluid cylinder, as disclosed in Japanese Patent Publication No. 59-14365, for example. So-called hydropneumatic suspension systems (HPS systems) are known.

Also known is a so-called active control suspension system (ACS system) that independently controls the flow rate to a fluid cylinder for each wheel to vary the suspension characteristics of the vehicle depending on the driving condition.

In a vehicle equipped with such an ACS device, that is, a vehicle equipped with AC8, the load of the vehicle body is supported only by the fluid pressure within the fluid cylinder. On the other hand, in the case of a general suspension device such as a strut type, the vehicle body load is supported by the fluid pressure in a fluid cylinder and the spring reaction force of a coil spring, etc., and a vehicle equipped with this suspension device is In contrast to the AC8 equipped vehicle mentioned above, it is called a passive suspension equipped vehicle.

(Problem to be Solved by the Invention) By the way, in the case of the above-mentioned ACS-equipped vehicle, when the various sensors and other devices in the AC8 device malfunction,
Control is stopped at the current vehicle height, but if the flow control valve, etc. that controls the flow rate to the fluid cylinder breaks down,
There is a problem in that all the fluid in the fluid cylinder is discharged and the vehicle height is significantly lowered.

The present invention has been made in view of the above, and its purpose is to focus in particular on bump stoppers that are provided to restrict wheel bumps in ACS-equipped vehicles as well as in passive suspension-equipped vehicles. However, this bump stopper is intended to ensure the vehicle height in the event of a failure of the ACS device.

(Means for Solving the Problem) In order to achieve the above object, the solution of the present invention is to control the supply and discharge of fluid in fluid cylinders disposed between the vehicle body and each wheel of the same vehicle type. Bump stopper of AC8 equipped vehicle in AC8 equipped vehicle equipped with suspension device (AC8 device) that can change suspension characteristics and passive suspension equipped vehicle equipped with suspension device equipped with shock absorber and spring member. The bump regulation position is set lower than that of the bump stopper of a vehicle equipped with a passive suspension.

(Function) With the above configuration, in the present invention, the A
In the CS system, when a failure occurs in which all the fluid in the fluid cylinder is discharged, such as when a flow control valve fails, the bump stopper whose bump restriction position is set lower than that of a vehicle equipped with passive suspension Displacement that shortens the relative distance between the vehicle body and the wheels is regulated, and a significant decrease in vehicle height is prevented.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 3 shows the overall structure of a vehicle suspension system according to an embodiment of the present invention. This suspension device is
This is an ACS device that makes the suspension characteristics variable, and the vehicle is called an AC5 equipped vehicle.

In FIG. 3, 1 is the vehicle body, 2F is the front wheel, and 2R is the rear wheel, and there is a space between the vehicle body 1 and the front wheel 2F, and a space between the vehicle body 1 and the rear wheel 2.
A fluid cylinder 3 is arranged between each R and R.

Each hydraulic cylinder 3 has a hydraulic chamber 3C defined by a piston 3b fitted into a cylinder body 3a. The upper end of the piston rod 3d connected to the piston 3b is connected to the vehicle body 1, and each cylinder body 3a is connected to a wheel 2F.

Connected to 2R.

A gas spring 5 is connected to the hydraulic pressure chamber 3C of each of the fluid cylinders 3 through a communication passage 4. Each gas spring 5 is divided into a gas chamber 5r and a hydraulic chamber 5g by a diaphragm 5C, and the hydraulic chamber 5g communicates with the hydraulic chamber 3C of the fluid cylinder 3.

Further, reference numeral 8 denotes a hydraulic pump, and reference numerals 9 and 9 denote flow control valves interposed in a hydraulic pressure passage 10 that communicates the hydraulic pump 8 with each fluid cylinder 3.
It has the function of supplying and discharging fluid (oil) to and adjusting the flow rate.

Further, 12 is a main pressure sensor that detects the oil discharge pressure of the hydraulic pump 8 (more specifically, the pressure of oil stored in accumulators 22a and 22b, which will be described later), and 13 is a main pressure sensor for each fluid cylinder 3.
a cylinder pressure sensor 14 for detecting the hydraulic pressure in the hydraulic pressure chamber 3c;
is the corresponding wheel 2F.

A vehicle height sensor 15 detects the vehicle height (cylinder stroke amount) of 2R, and 15 is the vertical acceleration of the vehicle (wheel 2F).

2R (spring boat speed)), and the detection signals from these sensors 12 to 15 are each input to a controller 19 having an internal CPU, etc., and are used for variable control of suspension characteristics.

Next, a hydraulic circuit for controlling supply and discharge of fluid to the fluid cylinder 3 is shown in FIG. In the figure, the hydraulic pump 8 is a variable displacement swash plate piston pump, and the hydraulic pump 21 for a power steering device is driven by a drive source 20.
are connected in two series. The hydraulic passage 10 connected to the hydraulic pump 8 includes three accumulators 22a, 22.
a and 22a are connected to each other at the same location, and
At the connection point, the hydraulic pressure passage 10 is branched into a front wheel side passage 10F and a rear wheel side passage 10R. Furthermore, the front wheel side passage 10F has a left front wheel side passage 10PL and a right front wheel side passage 10FI.
? Each passage is branched into 10 PL and 10 PI? The corresponding wheel fluid cylinder 3PL, 3PI? The hydraulic pressure chambers 3c are communicated with each other. On the other hand, one accumulator 22b is connected to the rear wheel passage 10R, and on the downstream side thereof, it is branched into a left rear wheel passage 10RL and a right rear wheel passage 10RR.
The corresponding wheel fluid cylinder 3RL, 3J? R
The hydraulic pressure chambers 3c are communicated with each other.

Each of the above fluid cylinders 3PL, 3FR, 3RL,
3I? Gas springs 5FL, 5FR, 5R connected to R
Specifically, each of L and 5RR is a plurality of numbers (in the figure, there are 4
gas springs 5a, 5b, 5c.
, 5d are connected in parallel to the hydraulic chambers 3c of the corresponding fluid cylinders 3 via the communication passages 4. Further, each of the gas springs 5a to 5d is provided with an orifice 25 interposed in a branch part of the communication path 4, and each of the orifices 25
The gas chamber 5 has a damping effect and a buffering effect of the gas sealed in the gas chamber 5. The communication path between the first gas spring 5a and the second gas spring 5b 4 is a damping force switching valve 26 that adjusts the passage area of the communication passage 4.
The switching valve 26 has two positions: an open position where the communication passage 4 is opened and a throttle position where the passage area is significantly narrowed.

Furthermore, an unload valve 27 and a flow control valve 28 are connected to the hydraulic passage 10 on the upstream side of the accumulator 22a. The unload valve 27 transfers the pressure oil discharged from the hydraulic pump 8 to the swash plate operating cylinder 8a of the hydraulic pump 8.
It has an introduction position where the oil is introduced to reduce the oil discharge amount of the hydraulic pump 8, and a discharge position where the pressure oil in the cylinder 8a is discharged, and the oil discharge pressure of the hydraulic pump 8 is set to a predetermined upper limit oil discharge pressure ( When the discharge pressure exceeds 160±10 kgf/cj), it switches from the discharge position to the introduction position, and this state is maintained until it falls below a predetermined lower limit discharge pressure (120±10kgf/cj). , the oil discharge pressure of the hydraulic pump 8 is within a predetermined range (120 to 160 kgf/
c) It has a function of holding and controlling.

The flow rate control valve 28 has an introduction position where pressure oil from the hydraulic pump 8 is introduced into the swash plate operating cylinder 8a of the hydraulic pump 8 via the unload valve 27, and an introduction position where the pressure oil in the cylinder 8a is unloaded. and a discharge position for discharging from the valve 27 to the reserve tank 29, and when the oil discharge pressure of the hydraulic pump 8 is maintained within a predetermined range by the unload valve 27, the throttle 30 arrangement part of the hydraulic pressure passage 10 It has a function of keeping the differential pressure between the upstream and downstream sides constant and controlling the oil discharge amount of the hydraulic pump 8 to keep it constant. Therefore, each fluid cylinder 3
Oil is supplied to the accumulator 22a.

This is done by storing oil at 22b (this oil pressure is called main pressure).

On the other hand, on the downstream side of the accumulator 22a of the hydraulic passage 10, there are four flow control valves 9, 9, corresponding to the four wheels of the vehicle. ...
is provided. Hereinafter, since the configuration of the parts corresponding to each wheel is the same, only the left front wheel side will be explained, and the explanation of the others will be omitted. That is, the flow rate control valve 9 is connected to a first switching valve 35 provided in the left front wheel side passage 10FL of the hydraulic pressure passage 10 and a low pressure line 36 that discharges oil from the left front wheel side passage 10FL to the reserve tank 29. and a second switching valve 37 provided therein. Each of the switching valves 35 and 37 has two positions, an open position and a closed position, and incorporates a differential pressure valve that maintains the hydraulic pressure at a predetermined value in the open position.

Further, a pilot pressure responsive check valve 38 is interposed in the left front wheel side passage 10FL between the first switching valve 35 and the fluid cylinder 3. The check valve 38 is supplied with the hydraulic pressure (main pressure) in the hydraulic pressure passage 10 upstream of the proportional flow control valve 9 (first switching valve 35) as a pilot pressure through a pilot line 39, and this pilot pressure is 40 kgf. It is provided to close when the temperature is below /c. In other words, the main pressure is 40 kg f
/ d or more, it becomes possible to supply pressure oil to the fluid cylinder 3 and to discharge the oil in the fluid cylinder 3.

In addition, in FIG. 4, 41 is the accumulator 2 of the hydraulic pressure passage 10.
This fail-safe valve is installed in a communication path 42 that communicates the downstream side of the accumulator 2a and the low-pressure line 36, and is switched to the open position in the event of a control failure, returning the stored oil in the accumulators 22a and 22b to the reserve tank 29, and reducing the high pressure. It has a function to release the state.

Reference numeral 43 denotes a throttle provided in the three pilot lines, which has the function of delaying the closing of the check valve 38 when the fail-safe valve 41 is opened. 44 is each fluid cylinder 3 r'L on the front wheel side.

This is a relief valve that opens when the oil pressure in the hydraulic pressure chamber 3C of the 3FR increases abnormally and returns the oil to the low pressure line 36.

A return accumulator 45 is connected to the low pressure line 36 and performs a pressure accumulating action when oil is discharged from the fluid cylinder 3.

Next, the assembly structure of the fluid cylinder 3 and the gas spring 5 will be explained using the fluid cylinder 3FR and gas spring 5PR for the right front wheel 2PR shown in FIGS. 1 and 2 as an example.

That is, in FIG. 1, the lower part of the cylinder body 3a of the fluid cylinder 3PR is connected to the wheel (front wheel) 2PR via the wheel support 51, while the upper end of the piston rod 3d is connected to the strut mount rubber unit 52.
It is connected to the vehicle body 1 via. piston rod 3
Gas springs 5P are arranged between the strut mount rubber unit 52 mounting portion d and the cylinder body 3a in order from the top.
a support member 53 that supports R at its upper end;
A bump stopper 54 is provided to restrict bumps on the wheel 2PR. The bump stopper 54 is the wheel 2P.
When the cylinder body 3a of the fluid cylinder 3PR rises with the bump of R, it comes into contact with the upper end surface of the cylinder body 3a to restrict the bump of the wheel 2PR. A cover 55 covering the top is integrally formed.

Further, a communication passage 4 communicating with a hydraulic pressure chamber 3c (see FIG. 3) in the fluid cylinder is formed in the piston rod 3d, and the communication passage 4 is connected to a branch communication passage formed in the support member 53. It communicates with the hydraulic pressure chamber 5g of the gas spring 5FR through 4a, and the above-mentioned throttle 43 is connected to the branch communication path 4a.
is provided.

Multiple gas springs 5a to 5d as gas springs 5PR
(see FIG. 4) are each disposed on the outer periphery of the fluid cylinder 3PR on the vehicle body side and supported by a support member 53.

FIG. 5 shows the upper part of a strut of a strut type suspension device as an example of a suspension device installed in a passive suspension equipped vehicle of the same type as the ACS equipped vehicle according to the embodiment of the present invention.

This strut a consists of a shock absorber b made of a fluid cylinder and a coil spring C as a spring member disposed around the upper outer periphery of the shock absorber b. The lower part of the cylinder body d of the shock absorber b is connected to the wheel via a wheel support (not shown), and the upper end of the piston rod e of the shock absorber b is connected to the vehicle body via a strut mount rubber unit f. Concatenated. The upper end of the coil spring C is supported by an upper spring seat g attached to the piston rod e, and the lower end is supported by a lower spring seat h attached to the cylinder body d. In the case of this strut type suspension device, the vehicle body load is caused by the hydraulic pressure (hydraulic pressure) in the cylinder body d of the shock absorber b.
and the spring reaction force of the coil spring C. In FIG. 5, i is a bump stopper that comes into contact with the upper end surface of the cylinder body d to restrict the wheel bump when the wheel bumps, and j is a bellows-shaped cover that covers the upper part of the shock absorber b.

A comparison is made between the suspension device of an ACS-equipped vehicle and the suspension device of a passive suspension-equipped vehicle according to an embodiment of the present invention (see comparison between FIG. 2 and FIG. 5).
, the bump stopper 54 of the ACS equipped vehicle has a lower surface that is closer to the cylinder body 3a than the bump stopper i of the passive suspension equipped vehicle.
The bump regulation position is set downward close to the upper end surface. For example, bump stopper i for vehicles equipped with passive suspension.
If the clearance Q1 between the lower surface and the upper end surface of the cylinder body d is approximately 60 mm, the clearance 92 between the lower surface of the bump stopper 54 and the upper end surface of the cylinder body 3a in an ACS equipped vehicle is half that amount. Approximately 3011 of these are set. In addition, all parts of the bump stopper i of a vehicle equipped with a passive suspension are made of a material with the same hardness (such as rubber), whereas the bump stopper 5 of a vehicle equipped with an ACS
4 is a lower part 5 on the side that comes into contact with the upper end surface of the cylinder body 3a.
4a and the upper part 54b are made of materials with different hardness, and the upper part 54b is used as a bump stopper 5 for vehicles equipped with passive suspension.
4, and the lower part 54a is made of a softer material (for example, urethane resin, etc.).

In addition, in FIG. 2, 60 is a resin bushing having a bearing function, and this bushing 60 is attached to the bump stopper 5.
4 is covered from the outside by a seal member 61 formed to abut against the support member 53 from the upper end.

Therefore, in the ACS-equipped vehicle of the above embodiment, by setting the bump restriction position of the bump stopper 54 lower than that of the passive suspension-equipped vehicle, the control system of the ACS device can prevent the flow rate control valve 9 from leaking and sticking. When a failure occurs in which all the fluid (pressure oil) in the hydraulic chamber 3c of the fluid cylinder 3 is discharged, the upper end surface of the cylinder body 3a hits the bump stopper at an early stage of the contraction movement of the fluid cylinder 3. 54 and restricts further contraction of the fluid cylinder 3, thereby preventing a significant drop in vehicle height.

Moreover, even when the bump regulating position of the bump stopper 54 is located downward as described above, the ACS device can control the supply and discharge of fluid to the fluid cylinder 3 so as to reduce the bump displacement of the wheel. Collision between the upper end surface of the cylinder body 3a and the lower surface of the bump stopper 54 can be prevented at times other than when there is a bump or when the AC5 device is out of order. Particularly, when the lower part 54a of the bump stopper 54 on the side that comes into contact with the cylinder body 3a is made of a relatively soft material as in the embodiment, the cylinder body 3a, the bump stopper 54 and the door (which can absorb the impact when they collide) - Also, from this, the lower surface of the bump stopper 54 can be lowered to the upper end surface position of the cylinder body 3a, ensuring a higher vehicle height in the event of a failure of the AC8 device. be able to.

Furthermore, the structure for securing the vehicle height in the event of a failure of the ACS device as described above is a simple structure in which the bump regulation position of the existing bump stopper 54, which regulates wheel bumps, is set downward. It can be easily implemented without changing the structure of the suspension device, and is highly practical.

Incidentally, in the above embodiment, the present invention is applied to a suspension device including both a fluid cylinder 3 and a gas spring 5 (that is, an HP
S device), but it is not limited to this HPS device; it is not limited to this HPS device.
Of course, it is also applicable to other ACS devices (other than PS devices).

(Effects of the Invention) As described above, according to the vehicle suspension device of the present invention, even when the ACS device fails, the bump stopper whose bump restriction position is set lower than that of a vehicle equipped with passive suspension significantly reduces the vehicle height. It is possible to prevent the decrease and ensure safety. Moreover, it has a simple structure and has excellent practical effects.

[Brief explanation of the drawing]

1 to 4 show embodiments of the present invention, FIG. 1 is a partially cutaway rear view showing the specific assembly of the fluid cylinder and gas spring, and FIG. Main parts of Figure 1 (
FIG. 3 is an enlarged view of the upper portion of the fluid cylinder, FIG. 3 is a schematic diagram of the overall configuration of the suspension device, and FIG. 4 is a hydraulic circuit diagram. FIG. 5 is a partially cutaway side view showing the structure of the upper part of the strut of the strut type suspension device. 1...Vehicle body, 2F...Front wheel, 2R...Rear wheel, 3(
3PL. 3PR, 3RL, 3RR)...Fluid cylinder, 5
4...Bump stopper for cars equipped with AC8, i...Bump stopper for cars equipped with passive suspension. Figure Figure

Claims (1)

[Claims] (1) The same vehicle model is equipped with an ACS-equipped vehicle whose suspension characteristics can be changed by controlling the supply and discharge of fluid in a fluid cylinder disposed between the vehicle body and each wheel, a shock absorber, and a spring member. In vehicles with passive suspension equipped with a suspension device, ACS
A vehicle suspension device characterized in that the bump stopper of the vehicle equipped with the passive suspension has a bump regulation position set lower than that of the bump stopper of the vehicle equipped with the passive suspension.