KR0172638B1 - Hydraulic circuit of active suspension system for a vehicle - Google Patents

Abstract

The present invention is to provide an active suspension device that controls the pressure of the hydraulic actuator attached to each wheel to actively control the state of movement of the vehicle to improve the riding comfort and control and stability that can not be obtained in the conventional shock absorber. will be.

In the present invention, the combination of the pressure setting holding valve and the main line pressure control valve makes it possible to carry out a sudden change of the vehicle immediately after starting / stopping the engine and to maintain a constant high level when the system is broken and parked by a simple structure. By controlling the opening degree of the pressure setting holding valve using, it is possible to reduce energy consumption and noise.

Description

Hydraulic Circuit of Vehicle Active Suspension

1 is a conventional active suspension hydraulic circuit diagram.

2 is a hydraulic circuit diagram of the present invention.

3 is a pressure signal band control pressure diagram of the main pipeline pressure control valve of the present invention.

4 is a pressure signal band control pressure diagram of the proportional pressure control valve of the present invention.

5 is a pressure versus flow chart of the relief valve of the present invention.

6 is a pressure versus flow chart of the set pressure maintaining valve of the present invention.

7 is a pressure change diagram between the main line pressure control valve and the set pressure maintaining valve of the present invention.

8 is a diagram showing the pressure change according to the operation of the main pipeline pressure control valve and the set control holding valve of the present invention.

9 is a cross-sectional view illustrating main parts of the multifunctional valve unit according to the present invention.

10 is a cross-sectional view of the main portion of the pressure control valve unit according to the present invention.

* Explanation of symbols for main parts of the drawings

1: Hydraulic pump 2: 2FR-2RL. Hydraulic Actuator

3: 3F, 3R front / rear valve unit 4: controller

5: oil tank 10: accumulator for pump pulsation absorption

21 damping sub accumulator 22 piston damping valve

23: body attenuation valve 31: main pipe pressure control valve

32FR to 32RL: Proportional pressure control valve 33, 37F, 37R: Filter

34: Fail relief valve 35: Main check valve

36F, 36R: main accumulator 38F, 38R: return accumulator

39a: damping orifice 39b: oil cooler

39c: Set pressure holding valve 40: Check valve for preventing abnormal return pressure

41: vehicle position change detector 42: abnormal state detector

According to the present invention, in the conventional passive suspension vehicle, the pressure of each hydraulic actuator is continuously controlled by installing a proportional pressure control valve in the vehicle suspension system against the limitation caused by the design specification in which the riding comfort and safety improvement are in conflict with each other. By suppressing the vibration generated according to the driving condition, the vehicle can be kept as horizontal as possible to improve the riding comfort, and the vehicle posture control and maneuverability can be controlled by continuously controlling the pressure of each hydraulic actuator during turning, braking, and steering. It provides a hydraulic circuit of active suspension system that can reduce the flow rate and realize energy efficiency and noise by improving the stability at the same time, but the structure is simplified by forming the multifunctional valve unit and the pressure control valve unit in one block body. This facilitates installation work and realizes both ride comfort and control stability at the same time. Not only will they have to in order to minimize energy consumption and noise.

In general, an active suspension device that minimizes vehicle posture change during acceleration, deceleration, steering, and turning, and achieves optimum movement characteristics of the vehicle should be able to realize both ride comfort and steering stability with a simple structure. do.

To this end, the essential performance required by the active suspension hydraulic circuit, that is, the engine maintains a constant high pressure when the engine is stopped and parked, and prevents the vehicle from rapidly changing by smooth pressure changes immediately after the engine is started and immediately after the engine is stopped. In the event of a failure, it is necessary to maintain a high pressure change and maintain a constant high pressure by smooth pressure fluctuations, and to restore energy to a low pressure as much as possible.

While driving the vehicle (in normal control), the supply pressure can be maintained and the pressure can be controlled, and the return pressure must be zero to improve the efficiency.The structure is simple, so the volume and weight are small, and the energy consumption is low. At the very least, there is a need for a system that is not restricted by the application model.

As described above, the vehicle's active suspension system (Acvtive Suspension System) for controlling the state of movement of the vehicle by the hydraulic actuator is a hydraulic pump 100 as the main supply source, the actuator 200 corresponding to each wheel, the actuator 200, the actuator The control valve unit 300 and the multifunctional valve unit 400 for controlling the pressure of 200 are provided.

In order to absorb the pulsation of the hydraulic pump 100, a filter 103 and a check valve 104 for preventing damage to the filter are installed between the pump pulsation absorbing accumulator 101 and the relief valve 102 for setting the system pressure. On the return side, there is an oil tank 500 that returns through the oil cooler 105 to cool the oil.

Actuator 200 corresponding to each wheel is composed of a sub-accumulator 201 and a damping orifice 202, the control valve unit 300 is the pressure of each of the hydraulic actuator 200 is installed in the front and rear wheels The control valve unit 300 is provided with a main accumulator 301 on the supply side and a return accumulator 302 on the return side.

In addition, the multifunction valve 400 has a structure in which various types of valves, such as a valve for system failure, are incorporated.

In the active suspension device, the oil discharged from the hydraulic pump 100 is supplied to a cylinder of each hydraulic actuator 200 in which a system pressure is set by a relief valve 102 and correspondingly disposed on each wheel. By evacuating, the pressure is controlled to control the posture and the motion of the vehicle.

The multi-function valve unit 400 maintains the control pressure of the constant garage maintenance when the engine stops and parks, and the soft pressure fluctuation function when the system breaks down with a smooth pressure fluctuation function immediately after the engine starts and immediately after the engine stops. Control pressure holding function.

When the main accumulator 301 requires a large amount of flow rate in the actuator 200, the main accumulator 301 compensates for the shortage of the supply oil from the hydraulic pump 100, absorbs the fluctuation of the supply pressure, and maintains the return pressure after stopping the engine. In this case, the lowering of the return pressure due to leakage is softened to prevent the high profile change.

At this time, the return accumulator 302 absorbs the pulsation of the return hydraulic pressure, and the sub accumulator 201 and the damping orifice 202 of the actuator 200 disposed corresponding to each wheel absorb high frequency vibration.

However, in the related art, hydraulic components having various functions are used for controlling the state of movement of the vehicle by the actuators 200 corresponding to the wheels. However, since there is not enough space in the vehicle to mount various hydraulic parts, a compact design is required to use them more efficiently.

Furthermore, in order to control the pressure of the multifunction valve unit 400 and the actuator 200 of each wheel. By using various types of valves such as ON / OFF solenoid valves in the respective control valve units 300 and 300 and the multifunction valve unit 400 in the rear wheel, the flow path of the multifunction valve unit 400 is complicated, and the workability and assembly are as follows. Because of poor quality, the defect rate is high.

In addition, the weight is heavy and bulky is limited to the application model, the flow path is complex, not only limited to the mounting space, but also caused vibration by hydraulic pulsation.

And by using the fixed displacement hydraulic pump 100, the oil is returned to the oil tank 500 by the relief valve 102 at high pressure during system failure driving, so the energy loss is large, the system pressure is high pressure noise There were problems such as increasing.

In order to solve the conventional drawbacks as described above, the applicant of the present invention has filed a prior application invention (Patent Application No. 95-44211).

The prior application is to control the pressure of the hydraulic actuator attached to each wheel to actively control the state of movement of the vehicle to ride comfort and control that can not be obtained in the conventional shock absorber. It is to provide an active suspension that improves the stability at the same time.

In the present invention, the combination of the set pressure maintaining valve and the main line pressure control valve makes it possible to prevent the sudden change of the vehicle immediately after starting / stopping the engine and to maintain the constant vehicle high level when the vehicle is parked by a simple structure. It aims to reduce energy consumption and noise by controlling the opening degree of the pressure setting holding valve using a valve.

In the present invention, in the wiring of each of the main valves and cocks, etc. in the above-described configuration of the invention, it is an object to install more simply and to minimize energy consumption and noise.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the active suspension device for a vehicle according to the present invention will be described in more detail the configuration and effect.

As shown in FIG. 2, the present invention is divided into a hydraulic pump (1), which is a large hydraulic supply source, a hydraulic actuator (2: 2FR to 2RL) disposed corresponding to each wheel, and a front wheel for controlling the pressure of the actuator (2). The rear wheel valve unit 32 is divided into 3F and 3R, and a controller 4 for controlling the control valve unit 3 according to the detection signal of the detectors 41 and 42 detected by detecting a change in attitude and an abnormal state of the vehicle. do.

The hydraulic pump (1) is composed of a variable displacement hydraulic pump, an oil tank having a pump pulsation absorption accumulator (10) on the output side of the hydraulic pump (1), a check valve for preventing damage to the filter and strainer on the input side (5) is installed.

In the hydraulic actuators 2: 2FR to 2RL disposed corresponding to each wheel, a damping subaccumulator 21 is provided on one side of the cylinder 20, and a piston damping valve 22 and a body attenuation valve 23 are provided inside the cylinder 20. ) To be built in.

The control valve unit 3 is composed of a front wheel valve unit 3F and a rear wheel valve unit 3R, and the front wheel valve unit 3F and the rear wheel valve unit 3R have a main passage pressure control valve for controlling a vehicle posture ( 31 and proportional pressure control valves 32FR to 32RL controlled by the solenoid 32S are provided.

The front wheel valve unit 3F includes a filter 33 provided with a check valve for preventing damage to the filter, and a fail relief valve 34 for preventing a system pressure surge due to the light of the swash plate control mechanism of the hydraulic pump 1. ) And a main check valve 35 are provided, and a filter 37F is installed as a contaminant filtration device in front of the front wheel side main accumulator 36F and the front wheel side proportional pressure control valves 32FR and 32FL for accumulating pressure. do.

The return line Lr is provided with a front wheel return accumulator 38F and a damping orifice 39a, which is necessary for maintaining the neutral pressure when the system is abnormal or the engine is stopped, and the oil cooler 39b and the set pressure are maintained in the tank line Lt. A valve 39c and a check valve 40 for preventing an abnormal return pressure are provided.

The air vent 391 connected in parallel with the set pressure maintaining valve 39c is a main pressure setting valve so that oil can be forcibly drained when replacing a component on a circuit that maintains a neutral pressure in the event of a system failure or engine stop. It is connected with 39c.

The rear wheel valve unit 3R is provided with a rear wheel filter 37R as a contaminant filtration device in front of the rear wheel main pressure accumulator 36R and the rear wheel pressure control valves 32RR, 32RL for accumulating pressure, and a return line Lr. Is composed of a rear wheel return accumulator 38R and a check valve 40 for preventing an abnormal return pressure.

The controller 4 for controlling the pressure of the hydraulic actuators 2FR to 2RL disposed corresponding to each wheel includes a vehicle attitude change detector 41 for detecting a change in attitude of the vehicle, and an abnormal state detector for detecting abnormal conditions of the vehicle ( The control valve units 3F and 3R are controlled in accordance with the detection signals X and Y of the signal 42.

In particular, in the present invention, as shown in FIG. 9, the multifunction valve unit 400 includes a set pressure maintaining valve 39c, a pressure discharge cock 391, a main pipeline pressure control valve 31, and a fail relief valve 34. And the vane check valve 35 in one block body 404, and the pressure control valve unit 300 as shown in FIG. 10 shows the proportional pressure control valve 32 and the fail check valve. There is a feature in that the 40 is formed in one block body 303.

Referring to the operation relationship of the vehicle active suspension configured as described above is as follows. The oil discharged from the variable displacement hydraulic pump 1 as a hydraulic source is supplied to and discharged from the cylinder 20 of the hydraulic actuators 2FR to 2RL disposed corresponding to each wheel to control the state of movement of the vehicle and The motion state of the vehicle can be optimally controlled by the proportional solenoid 32S of the proportional pressure control valves 32FR to 32RL by the detection signal X of the vehicle attitude change detector 41. do.

Therefore, various functions such as maintaining a constant height due to a system failure and preventing a sudden change of the vehicle immediately after starting the engine and immediately after stopping the engine are performed by the proportional solenoid 31S of the main line pressure control valve 31 by the detection signal Y of the abnormal state detector 41. Is performed by a combination of the set pressure holding valves 39c which control the pilot pressure of the pilot pipe line Lp and switch the opening degree by the pilot pressure, and the damping orifice 39a of the return pipe Lr is a system failure. It is possible to maintain the set neutral pressure by preventing the return of oil to the tank suddenly at the time of engine or engine stop.

In addition, the prevention of the increase in the return pressure abnormality at the time of system failure driving and the conversion of the riding load and the number of passengers is performed by the return pressure abnormality preventing check valve 40 integrally formed with the vent 401 to discharge the air.

The main pipeline pressure control valve 31 adjusts the pressure of the pilot pipeline Lp, and the return pipeline Lr according to the spring force of the set pressure maintaining valve 39c controlled by the pilot pipeline Lp and the characteristics of the applied vehicle. ), The opening pressure of the set pressure holding valve 39c is changed by the pressure of the pilot pipeline Lp controlled by the proportional solenoid 31S by setting the pressure of the main pipeline Lm and the control pipeline Lc. To maintain the holding pressure.

Then, when the system breaks down, due to the pressure fluctuation of the return line Lr according to the opening degree switching of the set pressure holding valve 39c, it is possible to prevent the sudden change of pressure due to the pressure change of the cylinder 20 in the hydraulic actuators 2FR to 2RL. , Front wheel main accumulator 36F in front wheel valve unit 3F, front wheel return accumulator 38F and rear wheel main accumulator 36F in rear wheel valve unit 38R, rear wheel return accumulator 38R and It is made by a check valve 40 for preventing an abnormal return pressure.

At this time, the pressure drop caused by the small flow loss is accumulated by the front wheel main accumulator 36F, the front wheel return accumulator 38F, the rear wheel main accumulator 36R, and the rear wheel return accumulator 38R. The supply of prevents the pressure drop caused by the micro flow loss.

The vent 391 connected in parallel with the set pressure maintaining valve 39c is a device for forcibly discharging oil when replacing a component on a circuit that maintains a neutral pressure in the event of a system failure or engine stop.

On the other hand, in the hydraulic circuit of an active suspension device for a vehicle, the supply pressure must be maintained and the pressure control function is performed during engine rotation (normal control), and the return pressure must be zero to improve efficiency.

To this end, in the hydraulic circuit of the present invention, when a system failure occurs during normal control, a smooth garage pressure is maintained, and when there is no consumption flow rate of the hydraulic actuator, the main pipe and the system pipe (Ls) become the maximum relief pressure and the system pipe (Ls). When the swash plate angle of the variable displacement hydraulic pump 1 operated by the pressure of N0 is zero, and the discharge flow rate is zero, the horsepower of the pump is also zero, thereby improving energy efficiency and reducing noise.

3 is a diagram showing the pressure change of the main line Lm against the pressure of the control current value IBY of the main line pressure control valve 31, and is the main line of the main line to the pressure of the control current value IBY. The pressure change of (Lm) has a dead zone (Dz), and it can be seen that it changes linearly.

By continuously controlling the pressure in the main pipe line Lm according to this characteristic, it is possible to prevent the high level change immediately after starting the engine, and to control the opening and closing of the set pressure holding valve 39c to maintain the high level pressure during system breakdown and parking. do.

At the same time as the system line Ls and the main line Lm are switched, the main circuit line Lm is connected to the return line Lr, so that the oil in the circuit does not change even if a pressure change occurs in the cylinder 20 in the hydraulic actuators 2FR to 2RL. Because of the circulating structure, it is possible to maintain optimum ride comfort and steering stability even during operation in case of system failure.

4 is a diagram showing the relationship of control pressure change of the cylinder 20 in the hydraulic actuators 2FR to 2RL with respect to the pressure of the control current values IFR to IRL of the proportional pressure control valves 32FR to 32RL. It can be seen that the control pressure change of the hydraulic actuators 2FR to 2RL cylinder 20 changes linearly with respect to the pressure of the current values IRR to IRL.

By this characteristic, the pressure of the hydraulic actuators (2FR to 2RL) cylinder 20 is continuously controlled by the pressure of the control current values IFR to IRL of the proportional pressure control valves 32FR to 32RL, thereby changing the attitude of the vehicle. In addition, the riding comfort is improved by keeping the vehicle as horizontal as possible by suppressing the vibration generated according to the driving state.

In addition, vehicle attitude control and steering during turning, braking and steering. Stability can be improved at the same time, By reducing the vehicle attitude change during deceleration, steering and turning, the movement characteristics of the vehicle can be optimized, that is, the riding comfort and the steering stability can be improved at the same time.

5 is a diagram of an override characteristic with respect to the pressure of the fail relief valve 34 as in the present invention.

The pressure override characteristic is the pressure change characteristic from cracking pressure Pck1 to the total flow pressure Pmax. The better the pressure override characteristic, the higher the flow rate at the same pressure. The valve 34 can prevent the pressure surge of the system pipe Ls caused by the failure of the swash plate control mechanism of the hydraulic pump 1.

Therefore, during normal control without failure of the swash plate control mechanism, the relief pressure of the hydraulic pump 1 is set to the cracking pressure Pck1 of the fail relief valve 34 to be lower than the flow rate leaking through the fail relief valve 34. Since this is Zero, it can improve energy efficiency and reduce noise.

When the system breaks down, the swash plate angle of the variable displacement hydraulic pump (1) operated by the pressure of the system pipeline (Ls) is controlled to zero, so there is no discharge flow rate. Noise can be reduced.

6 is a diagram of an override characteristic with respect to the pressure of the set pressure holding valve 39c as in the present invention.

A pilot pressure sensitive check valve that is opened and closed by the pressure of the pilot pipe line Lp controlled by the main pipe pressure control valve 31 at the time of engine stop and system failure, and the cracking pressure according to the pressure rise of the pilot pipe line Lp. It opens at (Pck2) and opens completely at (Pck3).

It can be seen that the good pressure override characteristics result in a smooth garage holding pressure when the engine is held at the engine stop and the system breakdown.

7 is a diagram showing the pressure change caused by the operation of the main pipeline pressure control valve and the set pressure maintaining valve in the hydraulic circuit of the active suspension system, such as during normal control immediately after starting the engine, immediately after stopping the engine, and during parking. The main line pressure (= pilot pressure) diagram L2 of) changes the pressure of the pilot line Lp according to the control signal IBY applied to the proportional solenoid 31, and sets the pressure according to the pressure change of the pilot line Lp. The holding valve 39c opens and closes.

Since the pump is stopped when the engine is stopped, i.e. when parking (0 to TO), the pump discharge pressure (system pipeline pressure) diagram L3 is zero, and the main pipeline pressure control valve 31 and the set pressure holding valve 39c. ), The pressure in the main pipe line Lm and the return pipe Lr is maintained at the vehicle holding pressure Pn.

When the engine is started at the TO time, the system pipeline pressure is instantaneously increased to the system pressure Ps, which is the pressure set by the swash plate control mechanism of the hydraulic pump 1 by the rotation of the pump.

Main pipeline pressure control for preventing the rapid change of the vehicle due to the pressure rise of the system pipeline Ls by the operation of the hydraulic pump 1 immediately after the engine starts, that is, the pressure change of the cylinder 20 in the hydraulic actuators 2FR to 2RL. The control signal IBY is gradually increased to In by the proportional solenoid 31S from time T1 to time T2 by the valve 31.

The pressure control valve raises the control signals IFR to IRL of the proportional solenoid 32S of the pressure control valves 32FR to 32R for the time period T1 to T2 so that the control target value, i.e., the control pressure of the control line Lc becomes the high holding pressure Pn. ), And immediately after the engine is started, the modes (TO to T4) are terminated, and in the engine operation mode (T4 to T5), the pressure control valves (32FR to 32R) are normally operated in accordance with the command signals IFR to IRL of the controller 4. Will be controlled.

Therefore, when the control signal In is raised to Ick2 at the time T2, the pressure in the main pipe rises and the set pressure holding valve 39c opens.

When the control signal of the main pipe pressure control valve 31 becomes ICk3, the pressure in the main pipe further rises and the set pressure holding valve 39c is completely opened at a time T3 at which the pressure of the set pressure holding valve 39c rises to the pressure Pck3. ,

At this time, the pressure in the return line becomes the state of low pressure (Pmin), that is, zero pressure.The pressure control valve of the main line is completely opened until the T4 time, and the system line and the main line are opened to enter the engine operation mode (T4 to T5). The control valves 32FR to 32RL can perform normal control in accordance with the command signals IFR to IRL of the controller 4.

The control signal IFR to IRL of the controller 4 becomes the proportional solenoid 32S of the proportional pressure control valves 32FR to 32RL by the detection signal X of the vehicle position change detector 41, and the hydraulic actuators 2FR to 2RL. The vehicle attitude is controlled by controlling the pressure of the cylinder 20.

In addition, normal control is performed at times T4 to T5, and during normal control, the main control line pressure control valve 31 is completely opened (that is, the pilot pressure Pmax of the pile line Lp) to reduce the return flow rate, thereby reducing the consumption flow rate and returning line By setting the pressure of (Lr) near the zero pressure (Pmin), the energy consumption is minimized.

When the engine is selected at time T5, the hydraulic pump stops, and the pressure in the system pipe is momentarily zero, and the pressure control valve of the main pipe line is prevented from the sudden change caused by the pressure change of the hydraulic actuator (2FR to 2RL) cylinder 20. (31) When the proportional solenoid 31S gradually decreases the control signal IBY to T6 time and the set pressure holding valve starts to close in Ick3, and the set pressure holding valve closes completely in Ick2, the pressure in the main and return lines becomes cold. It becomes Pn which is a holding pressure.

During the time T5 to T7, the pressure control valves 32FR to 32RL control the control signals IFR to IRL of the proportional solenoid 32S so that the pressure in the control pipe is controlled to the high holding pressure Pn to maintain the high holding pressure Pn. do.

When the high maintenance pressure is reached at time T7, the energization of the control signal IBY is stopped from the proportional solenoid 31S of the main pressure control valve 31, the energization of the control signal IBY is stopped and at the same time the pressure control valves 32FR to 32RL. The control signals IFR to IRL of the proportional solenoid 32S are also interrupted to enter the parking mode.

If a failure occurs in the system while driving, the control signal IBY and the pressure control valves 32FR to 32RL are controlled by the proportional solenoid 32S to the proportional solenoid 31S of the main pipeline pressure control valve 31 as shown in FIG. The energization of the signals IFR to IRL is stopped.

When energization of the main line pressure control valve 31 is stopped at time TO, the main line and the return line are ventilated, so that the main line pressure decreases and the return line pressure increases.

When the main pipe pressure becomes lower than the set pilot pressure of the set pressure holding valve 39c, the set pressure holding valve 39c is closed. From this time, the main pipe pressure and the return pressure become the garage holding pressure Pn.

On the other hand, since the pressure of the system pipeline Ls becomes the maximum pressure Ps set by the swash plate control mechanism of the hydraulic pump 1, the hydraulic pump 1 of the variable displacement type hydraulic pump 1 operated by the pressure of the system pipeline Ls is operated. Since the swash plate angle is zero, there is no discharge flow rate, so the horsepower of the pump becomes zero, improving energy efficiency and reducing noise.

As described above, the present invention controls the pressure in the main pipe by using the main pipe pressure control valve 31 to open the set pressure holding valve 39c. By controlling the closing, preventing the sudden change of the vehicle immediately after starting / stopping the engine and maintaining a constant height at the time of system failure and parking, it is performed by a simple structure by the set pressure maintaining valve 39c and the main line pressure control valve 31, When the system malfunctions, the discharge flow rate of the hydraulic pump 1 becomes zero, which can reduce energy and reduce noise.

As described above, the present invention controls the pressure of the hydraulic actuator attached to each wheel to actively control the state of movement of the vehicle, so that the comfort and steering which cannot be obtained in the conventional shock absorber. Stability can be simultaneously realized, and in particular, the present invention provides the multifunction valve unit 400 with a set pressure maintaining valve 39c, a pressure discharge cock 391, a main pipeline pressure control valve 31, and a fail relief valve ( 34 and the main check valve 35 in one block body 404, the proportional pressure control valve 32 and the fail check valve 40 described above the pressure control valve unit 300 Since it is comprised in the block body 303, it can be easily installed and repaired by a simple structure, and the ride comfort and control. Stability can be realized simultaneously, and there is an advantage of minimizing energy consumption and noise.

Claims (1)

The front wheel which controls the pressure of the hydraulic pump (1) used as a hydraulic supply source, the hydraulic actuator (2; 2RF-2RL) arrange | positioned corresponding to each wheel, and the said actuator (2). A rear wheel valve unit 3 (3F, 3R) and a controller 4 for controlling the control valve unit 3 in accordance with the detection time of the detectors 41 and 42 detected by detecting a change in attitude and an abnormal state of the vehicle are provided. In addition, the hydraulic pump 1 is a variable displacement hydraulic pump, the pump pulsation absorption accumulator 10 on the output side of the hydraulic pump 1, the oil on the input side has a filter and a check valve for preventing damage to the strainer The tank 5 is installed, and the hydraulic actuators 2: 2FR to 2RL have a damping sub accumulator 21 on one side of the cylinder 20, and a piston damping valve 22 and a body attenuation valve inside the cylinder 20. 23 is incorporated, and the front wheel valve unit 3F and the rear wheel valve unit 3R are controlled by the main passage pressure control valve 31 and the solenoid 32S for controlling the vehicle posture. 32RL is provided, the front wheel valve unit (3F) is provided with a strainer check valve for preventing damage to the strainer ( 33), a fail relief valve 34 and a main check valve 35 are installed to prevent the system pressure surge due to the failure of the swash plate control mechanism of the hydraulic pump 1; In the front of the main accumulator 36F, the front wheel proportional pressure control valves 32FR and 32FL, the filter 37F as a contaminant filtration device, and the return line Lr, the front wheel return accumulator 38F and a system abnormality. A damping orifice 39a, which is necessary for maintaining the neutral pressure when the engine is stopped, is installed, and an oil cooler 39c, a set pressure holding valve 39c, and a check valve for preventing an abnormal return pressure are installed in the tank line Lt. The rear wheel valve unit 3R is provided with a rear wheel filter 37R as a contaminant filtration device in front of the rear wheel main pressure accumulator 36 and the rear wheel pressure control valves 32RR and 32RL for accumulating pressure, and the return line Lr. Of the active suspension device for a vehicle provided with a rear wheel return accumulator (38R) and a check valve (40) for preventing an abnormal return pressure. In the pressure circuit, the set pressure maintaining valve 39c, the pressure discharge cock 391, the main pipeline pressure control valve 31, the fail relief valve 34, and the main check valve 35 are provided. The pressure control valve unit formed of the multi-function valve unit 400 formed in the block body 404 of the block body 404, and the above-described proportional pressure control valve 32 and the fail check valve 40 in one block body 303 ( Hydraulic circuit of an active suspension for a vehicle, characterized in that formed by 300).