JPH05139136A - Suspension device - Google Patents

Abstract

PURPOSE:To enable predetermined vehicle floor-height control and riding comfort control to be made with a reduced number of parts in use by performing high or low control in level of the pressure of an actuator directly in accordance with the state of a road surface on which a vehicle runs, and by impacting a shock absorber function to the actuator in case of an operating oil supply means kept inoperative. CONSTITUTION:A bidirectional pump 8 is normally or reversely revolved in accordance with the state of a running road surface. Actuators 1 which are disposed at four wheel portions of a vehicle are extended or retracted through such normal or reverse revolution, by which the pressure of each actuator 1 is controlled to be high or low. By this, occurrence of a change in vehicle height at each four-wheel portion of the vehicle is prevented so as to make an attitude control of the vehicle. On the other hand, during a time period in which the pressure control for the actuator 1 is kept out of operation, damping valves 9b, 10b in first and second damping force generation mechanisms 9, 10 permit passing therethrough of the operating oil at the time when the actuators 1 are extended or retracted. In this case, predetermined damping forces are generated in the actuators 1 so that each actuator 1 may have a shock absorber function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a suspension device which is most suitable for use as an active suspension as a suspension system for vehicles.

[0002]

2. Description of the Related Art Various proposals have been made in the past for a suspension device used for an active suspension or the like as a suspension system of a vehicle. For example, in the suspension device shown in FIG. Supplying hydraulic fluid from a hydraulic source 2 via a control valve 3 to an actuator 1 which is a hydraulic cylinder arranged between an axle A (T is a tire) and a vehicle body B (only one wheel is shown in the drawing). By doing so, the pressure in the actuator 1 is increased, and the hydraulic pressure from the actuator 1 is discharged to the tank 4 via the control valve 3 to reduce the pressure in the actuator 1 to control the vehicle height in each part of the four wheels of the vehicle. I'm trying to do it.

A suspension spring (not shown) is interposed in the actuator 1, while a gas spring 1a and a damping valve 1b are attached (see FIG. 8).

The control valve 3 is so constructed as to be activated so-called by a command signal from the controller C. The controller C is mounted on the vehicle body B and has a sensor C1 for detecting longitudinal acceleration and lateral acceleration and a vertical movement. If signals from the sensor C2 that detects acceleration are input,
The detection values from the sensors C1 and C2 are processed by the controller C and output as command signals to the control valve 3.

On the other hand, as a specific hydraulic circuit for the above suspension device, for example, a hydraulic circuit having the structure shown in FIG. 8 is proposed.

That is, the hydraulic circuit includes a hydraulic pressure source 2 and a control valve 3.
And the control valve 3 and the tank 4
And the control valve 3 and the actuator 1 are communicated with each other via an oil passage L.

In the figure, only the front side of the vehicle is shown, and the rear side of the vehicle has the same structure, so its illustration is omitted.

In the supply passage 5, a flow control valve 5a,
The fail-safe valve 5b and the accumulator 5c are arranged in series, and the operation check valve 6 is provided in the discharge path 6.
a is provided, a relief valve 7a is provided in the communication passage 7 that connects the supply passage 5 and the discharge passage 6, and a fail-safe valve 3a is provided in parallel with the control valve 3. Is going to be done.

Therefore, according to the conventional suspension device controlled by the hydraulic circuit described above, the sensors C1 and C for detecting the condition of the vehicle appearing on the vehicle body B while traveling on the road surface.
The detection signals from 2 are input to the controller C, respectively, and the signals are output to the control valve 3 as signals processed based on the preset values in the controller C, and the actuator 1 is operated by the operation of the control valve 3. The pressure in the vehicle can be controlled to be high or low, and the vehicle height in each part of the four wheels of the vehicle can be actively controlled according to the situation of the road surface on which the vehicle travels.

[0010]

However, in the above-mentioned conventional suspension device, there is a fear that improvement in versatility cannot be expected.

That is, in the above-mentioned conventional suspension device, in addition to the control valve 3 for actively controlling the vehicle height of the vehicle according to the condition of the traveling road surface, the engine is turned off for a long time such as parking. A check valve for maintaining the vehicle height at the time of operation and an operating check valve 6a are required, and a fail-safe valve 5 for maintaining the vehicle height at the time of fail-safe is required.
b, fail-safe check valve 3a, etc. are required.

Therefore, due to the large number of devices, the number of assembling steps in the device is increased, the size of the entire device is increased, or the total weight is increased, and the production cost is increased. In order to connect the above-mentioned devices by piping, a large number of assembling steps are required when mounting the device on a vehicle, and improvement in versatility cannot be expected.

The present invention was devised in view of the above-mentioned circumstances, and the purpose thereof is, of course, that so-called active vehicle height control is possible, and valves only for that purpose are required. It is possible to maintain the vehicle height during parking or fail-safe without having to do so, yet to provide a suspension device that has the simple structure, excellent mountability, and low cost, and is expected to improve its versatility. ..

[0014]

In order to achieve the above-mentioned object, the basic structure of the present invention is arranged in each part of the four wheels of a vehicle so that the upper end is connected to the vehicle body and the lower end is connected to the axle. In a suspension device formed so as to control the pressure in the actuator by supplying / discharging hydraulic oil to / from the actuator to control the vehicle height in each part of the vehicle, the suspension device appears and disappears in the cylinder that constitutes the actuator. A bypass passage that communicates outside the cylinder with a rod-side oil chamber and a piston-side oil chamber, which are partitioned and formed in the cylinder by a piston that is continuously provided at the tip of a piston rod that is freely inserted and that slides in the cylinder; A hydraulic oil supply means arranged in the bypass passage and allowing bidirectional flow of hydraulic oil in the bypass passage. A first damping force generation mechanism that enables generation of a damping force when the discharged working oil passes, and a second damping force generation that enables generation of a damping force when the working oil discharged from the piston side oil chamber passes The damping force generation mechanism has a check valve for preventing the hydraulic oil from flowing out from the oil chamber in the cylinder communicating with the mechanism, and the passage of the hydraulic oil from the oil chamber in the cylinder. A damping valve that sometimes generates a damping force is provided.

The first damping force generating mechanism is arranged in an oil passage outside the cylinder which connects the rod side oil chamber and the tank side, while the second damping force generating mechanism is arranged in the piston side oil chamber. It is arranged either in the oil passage outside the cylinder that communicates with the tank side or in the piston.

Further, it is assumed that the damping valve in each damping force generating mechanism is set so that the generated damping force can be changed if necessary, and the hydraulic fluid supply means has a forward and reverse pump. Or a directional control valve is provided to allow bidirectional flow of hydraulic oil in the bypass passage.

[0017]

Therefore, when the vehicle height in each part of the four wheels of the vehicle changes depending on the condition of the road on which the vehicle travels, the change in vehicle height is detected by the sensors that detect the longitudinal acceleration, lateral acceleration and vertical acceleration of the vehicle body. While being detected, the detection signal from each sensor is input to the controller.

The controller arithmetically processes each of the above signals based on the preset location, and outputs this as a command signal to the hydraulic oil supply means.

The hydraulic oil supply means has, for example, a bidirectional pump capable of normal and reverse rotation, and when the bidirectional pump is normally rotated, supplies the hydraulic oil to the piston side oil chamber in the cylinder via the bypass passage. To make the actuator extend,
Increase the pressure at the actuator.

When the bidirectional pump is rotated in the reverse direction, hydraulic oil is supplied to the rod-side oil chamber in the cylinder via the bypass passage so that the actuator tends to contract and the pressure in the actuator is lowered.

As a result, the pressure in the actuators arranged in each part of the vehicle is controlled to be high or low in accordance with the condition of the road on which the vehicle is traveling, and the change in the vehicle height in each part of the vehicle is prevented to control the posture of the vehicle. Will be possible.

On the other hand, while the pressure control in the actuator is stopped, the first expansion / contraction of the actuator is performed.
The hydraulic oil passes through the damping valve in each of the second damping force generating mechanisms, and at this time, a predetermined damping force is generated, so that the actuator can have a shock absorber function.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

As shown in FIG. 1, a suspension device according to an embodiment of the present invention includes an actuator 1, a hydraulic oil supply means 8, a first damping force generating mechanism 9 and a second damping force generating mechanism 10. And have.

The actuator 1 is arranged in each part of the four wheels of the vehicle under the distribution of the suspension spring 1c, the upper end of which is connected to the vehicle body B and the lower end of which is connected to the axle A. A rod side oil chamber R1 and a piston side oil chamber R2 are defined in the cylinder 11 by a piston 13 that is continuously provided at the tip of the piston rod 12 that is the lower end in the figure.

The rod side oil chamber R1 and the piston side oil chamber R
2 is connected to the outside of the cylinder 11 by a bypass L1 provided therein, and a hydraulic oil supply means 8 is arranged in the bypass L1.

In this embodiment, a load cell C3 is provided between the upper end of the piston rod 12 and the vehicle body B.
Is provided and is set so that the pressure in the actuator 1 can be detected.

The hydraulic oil supply means 8 is constructed so as to enable bidirectional flow of hydraulic oil in the bypass L1. In this embodiment, the bidirectional motor 8a serving as a drive source and the bidirectional motor 8a are provided. A bidirectional pump 8b which is a hydraulic pressure source driven by a bidirectional motor 8a.

The bidirectional motor 8a is set so as to enable forward and reverse rotation, that is, to be selectively driven in either forward or reverse rotation by a command signal from the controller C. The pump 8b is normally rotated, and the bidirectional pump 8b is reversely rotated when the pump 8b is reversely rotated.

The controller C is mounted on the vehicle body B in the same manner as in the above-mentioned conventional example, and includes a sensor C1 for detecting longitudinal acceleration and lateral acceleration and a sensor C for detecting vertical acceleration.
It is assumed that the signals from the load cell C3 are also input in addition to the signals from the input signal No. 2 being input.

In this embodiment, the bidirectional pump 8b has a piston-side oil chamber R in the cylinder 11 at the time of normal rotation.
2 is supplied with hydraulic oil, and when it is reversed, the hydraulic oil is supplied to the rod side oil chamber R1 in the cylinder 11.

On the other hand, the first damping force generating mechanism 9 and the second damping force generating mechanism 10 respectively include check valves 9a and 10a for preventing the hydraulic oil from flowing out from the oil chamber in the cylinder, and the oil chamber in the cylinder. Damping valves 9b and 10b that enable generation of a damping force when the discharged hydraulic oil passes through.

In this embodiment, the first damping force generating mechanism 9 has an oil passage L2 provided outside the cylinder 11 so as to connect the rod side oil chamber R1 and the tank 4 to each other.
The second damping force generating mechanism 10 is disposed in an oil passage L3 provided outside the cylinder 11 so as to connect the piston side oil chamber R2 and the tank 4.

In the damping force generating mechanisms 9 and 10, check valves 9a and 10a and damping valves 9b and 10b are also provided.
Are set in parallel.

Therefore, in the above-described embodiment, for example, when the bidirectional pump 8b is normally rotated, the hydraulic oil from the tank 4 is stored in the check valve 9a and the cylinder 11 in the first damping force generating mechanism 9. The hydraulic oil is circulated in the bypass passage L1 via the rod-side oil chamber R1, and the hydraulic oil is supplied to the cylinder 11
It is supplied to the piston side oil chamber R2 inside.

At this time, since the piston side oil chamber R2 is communicated with the tank 4 via the damping valve 10b in the second damping force generating mechanism 10, the piston side oil chamber R2 and the rod side oil chamber R1 are connected to each other. Creates a differential pressure between.

Therefore, the oil pressure in the piston side oil chamber R2 becomes higher than that in the rod side oil chamber R1, and the piston 13 tends to move up in the cylinder 11, that is, the actuator 1 extends so that the actuator 1 The pressure at will be increased.

On the contrary, when the bidirectional pump 8b is rotated in the reverse direction, the working oil from the tank 4 passes through the check valve 10a in the second damping force generating mechanism 10 and the piston side oil chamber R2 in the cylinder 11. Is circulated in the bypass passage L1 and the hydraulic oil is supplied to the rod-side oil chamber R1 in the cylinder 11.

At this time, the rod-side oil chamber R1 is stored in the tank 4 through the damping valve 9b in the first damping force generating mechanism 9.
Since they are communicated with each other, a differential pressure is generated between the rod side oil chamber R1 and the piston side oil chamber R2.

As a result, the oil pressure in the rod-side oil chamber R1 becomes higher than that in the piston-side oil chamber R2, and the piston 13 tends to descend in the cylinder 11, that is, the actuator 1 contracts, and the actuator 1 is compressed. The pressure is reduced.

The change in pressure in the actuator 1 is detected by the load cell C3, and the position detected by the load cell C3 is input to the controller C as a so-called feedback signal.

On the other hand, when the hydraulic oil supply means 8 is stopped, the hydraulic oil does not flow through the bypass L1.
When the actuator 1 expands and contracts, the cylinder 1
1 from the rod-side oil chamber R1 via the damping valve 9b in the first damping force generating mechanism 9, and hydraulic oil from the piston-side oil chamber R2 from the second damping force generating mechanism 1.
It is discharged to the tank 4 side via the damping valve 10b at 0.

As a result, when the actuator 1 expands and contracts, a predetermined damping action is exerted in each of the damping generating mechanisms 9 and 10, so that the actuator 1 can be provided with a shock absorber function.

FIG. 2 shows that the damping valves 9c and 10c in the damping force generating mechanisms 9 and 10 are variable. In this embodiment, the damping valves 9c and 10c are controlled when the pressure of the actuator 1 is controlled. By making the damping force of the valves 9c and 10c high, it is possible to obtain a large control force for the actuator 1 with a small flow rate of hydraulic oil, and at the time of fail-safe, a suspension force that is low enough to generate a low damping force is not too hard. It becomes possible to

FIG. 3 shows an embodiment in which the configuration of the hydraulic oil supply means 8 is changed. A one-way motor 8c serving as a drive source is shown in FIG.
And a one-way pump 8d, which is a hydraulic pressure source driven by the one-way motor 8c, and a direction switching valve 8e.

In the case of this embodiment, the respective constitutions of the drive source and the hydraulic pressure source are simplified, and even if it is necessary to dispose the direction switching valve 8e, the durability of the entire hydraulic oil supply means 8 is improved. It becomes possible to make it cheap.

The suspension device shown in FIG. 4 shows another embodiment of the present invention, in which the first damping force generating mechanism 9 is used.
Is arranged in an oil passage L2 outside the cylinder 11 that communicates the rod-side oil chamber R1 and the tank 4 side with the second
The check valve 10a in the damping force generating mechanism 10 of the cylinder 11 that connects the piston side oil chamber R2 and the tank 4 side
Is arranged in the oil passage L3 outside of the cylinder 1, and the damping valve 10b in the second damping force generating mechanism 10 is
It is arranged on the piston 13 which slides in the inside 1.

Incidentally, in the piston 13, a check valve 10d is provided separately downstream of the damping valve 10b, and the check valve 10d is provided in the rod side oil chamber R1.
It prevents the hydraulic oil from flowing into the piston side oil chamber R2.

It goes without saying that the suspension apparatus according to this embodiment operates similarly to the suspension apparatus of the embodiment shown in FIG. 1, but according to this embodiment,
Since the damping valve 10b is arranged on the piston 13 in the cylinder 11, there is an advantage that the structure on the tank 4 side outside the cylinder 11 is particularly simple.

FIG. 5 shows that the damping valves in the damping force generating mechanisms 9 and 10 are variable damping valves 9c and 10c. The suspension device according to this embodiment has the same structure as that shown in FIG. As in the case of the embodiment shown in (1), the pressure control in the actuator 1 becomes easy, and it becomes possible to achieve a suspension under a low damping force at the time of fail safe.

In FIG. 6, the directional switching valve 8 is provided in the hydraulic oil supply means 8 as in the embodiment of FIG.

Of course, the hydraulic oil supply means 8 has a one-way motor 8c which is a drive source and a one-way pump 8d which is a hydraulic pressure source.

[0053]

As described above, according to the present invention, in order to control the pressure of the actuator according to the condition of the road surface on which the vehicle is traveling, the condition of the vehicle body is detected by each sensor provided on the vehicle body. By inputting this to the controller and operating the hydraulic oil supply means by the command signal from the controller to directly control the pressure of the actuator in high or low, the pressure control in the actuator is surely executed. When the hydraulic oil supply means is not actuated, the rod-side oil chamber and the piston-side oil chamber in the cylinder that make up the actuator are circulated through the damping valve in either damping force generating mechanism to provide the actuator with a shock absorber function. It becomes possible to have a certain vehicle height control and ride comfort control with a small number of parts. Score in the can because the structure easily allows reduction and weight reduction and cost cost reduction of assembly process,
It has a number of effects such as being cheap and excellent in mountability, and being optimal for expecting improvement in its versatility.

[Brief description of drawings]

FIG. 1 is a diagram showing a suspension device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an embodiment in which the configuration of a damping valve in a damping force generating mechanism is changed from the embodiment shown in FIG.

FIG. 3 is a diagram showing an embodiment in which the configuration of hydraulic oil supply means is changed from the embodiment shown in FIG.

FIG. 4 is a diagram showing a suspension device according to another embodiment of the present invention.

5 is a diagram showing an example in which the configuration of the damping valve in the damping force generating mechanism is changed from the example shown in FIG.

FIG. 6 is a diagram showing an embodiment in which the configuration of hydraulic oil supply means is changed from the embodiment shown in FIG.

[Explanation of symbols]

 1 Actuator 4 Tank 8 Hydraulic Oil Supply Means 9 First Damping Force Generating Mechanism 9a Check Valve 9b, 9c Damping Valve 10 Second Damping Force Generating Mechanism 10a Check Valve 10b, 10c Damping Valve 11 Cylinder 12 Piston Rod 13 Piston A Axle B vehicle body L1 bypass passage L2, L3 oil passage R1 rod side oil chamber R2 piston side oil chamber

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[Procedure amendment]

[Submission date] November 6, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a diagram showing a suspension device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an embodiment in which the configuration of a damping valve in a damping force generating mechanism is changed from the embodiment shown in FIG.

FIG. 3 is a diagram showing an embodiment in which the configuration of hydraulic oil supply means is changed from the embodiment shown in FIG.

FIG. 4 is a diagram showing a suspension device according to another embodiment of the present invention.

5 is a diagram showing an example in which the configuration of the damping valve in the damping force generating mechanism is changed from the example shown in FIG.

FIG. 6 is a diagram showing an embodiment in which the configuration of hydraulic oil supply means is changed from the embodiment shown in FIG.

FIG. 7 is a diagram showing how a suspension device is mounted on a vehicle.

FIG. 8 is a circuit diagram of a suspension device.

[Explanation of reference numerals] 1 actuator 4 tank 8 hydraulic oil supply means 9 first damping force generating mechanism 9a check valve 9b, 9c damping valve 10 second damping force generating mechanism 10a check valve 10b, 10c damping valve 11 cylinder 12 piston Rod 13 Piston A Axle B Body L1 Bypass path L2, L3 Oil path R1 Rod side oil chamber R2 Piston side chamber

Claims (2)

[Claims] Claim: What is claimed is: 1. A hydraulic fluid is supplied to and discharged from an actuator which is provided at each part of a vehicle and whose upper end is connected to a vehicle body and whose lower end is connected to an axle, thereby controlling the pressure in the actuator to control the pressure in the vehicle. In a suspension device formed so as to control the vehicle height in each part of the four wheels, a suspension device formed by a piston slidable in the cylinder is provided continuously with a tip of a piston rod that is inserted into and retractable from a cylinder that constitutes an actuator. A bypass passage that connects the rod-side oil chamber and the piston-side oil chamber, which are partitioned and formed in the cylinder, to each other outside the cylinder; And a first damping force generation mechanism that enables generation of a damping force when the hydraulic oil discharged from the rod-side oil chamber passes. And a second damping force generation mechanism that enables generation of a damping force when the hydraulic oil discharged from the piston side oil chamber passes, and each damping force generation mechanism communicates with the second damping force generation mechanism. A suspension device comprising a check valve for preventing the hydraulic fluid from flowing out of the cylinder and a damping valve for generating a damping force when the hydraulic oil passes from the oil chamber in the cylinder. 2. The first damping force generating mechanism is arranged in an oil passage outside the cylinder which communicates the rod side oil chamber and the tank side, while the second damping force generating mechanism is arranged in the piston. The suspension device according to claim 1, wherein