KR0166183B1 - Hydraulic circuit for vehicle active suspension system - 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.

According to the present invention, the combination of the pressure setting holding valve and the main line pressure control valve makes it possible to experiment with a simple structure to prevent the sudden change of the vehicle immediately after starting / stopping the engine and to maintain a certain level of parking during the parking and the main line pressure control valve. 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.

2 is a hydraulic circuit for the present invention.

3 is a pressure signal band control pressure diagram of the main line 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 control line pressure control valve and the set control holding valve of 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: attenuation sub accumulator 22: piston attenuation valve

23: body reducing 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: attenuation orifice 39b: oil cooler

39c: Set pressure maintaining 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 device against the limitation caused by the design specification in which the riding comfort and stability 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, improving the riding comfort, and continuously controlling the pressure of each hydraulic actuator during turning, braking, and steering, thereby controlling vehicle posture control and maneuverability and stability. It is to provide a hydraulic circuit of an active suspension device that can simultaneously improve the energy consumption and reduce the consumption flow rate and reduce 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, when the engine is stopped and the parking is maintained, maintains a constant high pressure. 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 it is possible to save energy when it is possible to return the return pressure as low 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. It is required to have a system that is not restricted by the type of vehicle.

In this way, the vehicle's active suspension system (Acvtive Suspension System) for controlling the movement state of the vehicle by the hydraulic actuator as shown in Fig. 1 is the hydraulic pump 100, the actuator 200 arranged in correspondence with 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 filter damage prevention check valve 104 are installed between the pump pulsation absorption 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.

The actuator 200 corresponding to each wheel is composed of a sub-accumulator 201 and an attenuation orifice 202, and the control valve unit 300 controls the pressure of each hydraulic actuator 200 which is divided into 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 several types of valves, such as a valve for system failure, are incorporated.

In this active suspension device, the oil discharged from the hydraulic pump 100 is supplied with pressure by supplying and exhausting the cylinder pressure of each hydraulic actuator 200 arranged in correspondence with each wheel by setting the system pressure by the relief valve 102. By controlling the position and the movement state of the vehicle.

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

When the main accumulator 301 requires a large amount of flow rate in the actuator 200 at once, it 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 the engine stops. In case of maintenance, the fall of return pressure caused by 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 attenuation 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 actuators 200 of each wheel, the control valve units 300 and 300 on the front and rear wheels and the on / off solenoid valves on the multifunction valve unit 400, respectively. By using a kind of valve, the flow path of the multifunctional valve unit 400 is complicated, and the workability and assemblability are not good, so that the defect rate is increased.

In addition, the weight is heavy and bulky to limit the application model, the flow path is complicated, 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 above-mentioned conventional problems, a patent application No. 17624 (hereinafter referred to as a first invention), filed by the applicant of the present invention, is known, and the present invention is a new invention that improves its shortcomings.

The invention of the present invention installs a proportional pressure control valve in a vehicle suspension system to continuously control the pressure of each hydraulic actuator, thereby suppressing vibrations generated according to driving conditions, thereby optimizing the vehicle's movement characteristics such as ride comfort, vehicle attitude, adjustability and stability. It was intended to provide a system that is lightweight and simple in structure, without being restricted by the applied vehicle.

In order to solve the conventional defects 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 to ride comfort and control that can not be obtained in the conventional shock absorber It is to provide an active suspension device that improves stability at the same time.

According to the present invention, the combination of the set pressure maintaining valve and the main line pressure control valve makes it possible to prevent a sudden change of the garage immediately after starting / stopping the engine, to maintain a constant garage at the time of system failure and engine stop, and at the time of parking by a simple structure. In addition, the purpose of the present invention is to reduce the energy consumption and noise by controlling the opening degree of the pressure setting holding valve using the main line pressure control valve.

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

As shown in FIG. 2, the present invention is largely divided into a hydraulic pump 1 serving as a 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 3: 3F, 3R, and the controller 4 which controls the control valve unit 3 according to the detection signal of the detector 41,42 which detected by detecting a change in the attitude | position of a vehicle, and an abnormal state, are divided. .

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 sub-accumulator 21 is provided on one side of the cylinder 20, and a piston damping valve 22 and a body damping valve 23 are disposed 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 sudden increase in system pressure due to a failure 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 pollutant 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 an attenuation orifice 39a for maintaining the neutral pressure when the system is abnormal or the engine stops, 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 vent 391 connected in parallel with the set pressure maintaining valve 39c is a main pressure set pressure maintaining valve so that oil can be forcibly drained when replacing a component on the circuit that maintains the neutral pressure in case of 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 and 32RL for accumulating pressure, and the return pipe Lr. The rear wheel side return accumulator 38R and the return pressure abnormality prevention check valve 40 are comprised.

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.

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 the 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 movement state of the vehicle and The movement state of the vehicle can be optimally controlled by the proportional solenoid 32S of the proportional pressure control valves 32FR to 32RL by means of 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 carried out by the combination of the set pressure holding valve 39c which controls the pilot pressure of the pilot pipe line Lp and switches the opening degree by the pilot pressure, and the attenuation 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 check valve 40 for preventing the abnormality of the return pressure configured integrally 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 controlled by the pressure of the pilot pipe Lp controlled by the proportional solenoid 31S by setting the pressures of the main pipe Lm and the control pipe Lc. To maintain the holding pressure.

Then, in the event of a system failure, by preventing a change in the pressure of the cylinder 20 in the hydraulic actuators 2FR to 2RL by the pressure fluctuation of the return line Lr according to the opening switching of the set pressure holding valve 39c, , 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 3R, rear wheel return accumulator 38R And a check valve 40 for preventing an abnormal return pressure.

At this time, the pressure drop due to 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 so that the system pipe (Ls) When the swash plate angle of the variable displacement hydraulic pump 1 operated by the pressure 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 pipe line Lm with respect to the pressure of the control current value IBY of the main pipe pressure control valve 31, and the main pipe line Lm with respect to the pressure of the control current value IBY. The pressure change of) has 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.

When the system line Ls and the main line Lm are switched at the same time, the main line Lm and the return line Lr are connected to each other so that the oil in the circuit may be reduced 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.

FIG. 4 is a diagram showing a control pressure change relationship 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 IRR 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, it is possible to improve the vehicle attitude control and steering and stability at the time of turning, braking and steering, and to minimize the change of vehicle attitude during acceleration, deceleration, steering and turning, thus optimizing the movement characteristics of the vehicle. Riding comfort and steering stability can be improved at the same time.

5 is an over-ride characteristic diagram for the pressure of the fail relief valve 34 as in the present invention.

The pressure override characteristic is a 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 pipe (Ls) is controlled to zero, so there is no discharge flow rate, so the pump horsepower is zero, improving energy efficiency and 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 which is opened and closed by the pressure of the pilot pipe line Lp controlled by the main line pressure control valve 31 at the time of engine stop and system failure, and the cracking pressure in response to the pressure rise of the pilot pipe line Lp. It opens at (Pck2) and opens completely at (Pck3).

It can be seen that when the engine holding pressure is at the engine stop and the system breakdown due to the good pressure override characteristic, it becomes a soft garage holding pressure.

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 normal control immediately after starting the engine, immediately after stopping the engine, and 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 T0), the pump discharge pressure (system pipeline pressure) line 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 time T0, 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 starting the engine, 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 solenoids 32S of the pressure control valves 32FR to 32R for the time period T1 to T2 so that the control target value, that is, the control pressure of the control pipe line Lc, becomes the high holding pressure Pn. (T0 to T4) immediately after the engine is started, 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 to the cracking pressure Pck2 of the set pressure holding valve 39c, thereby opening the set pressure holding valve 39c.

When the control signal of the main pipeline pressure control valve 31 reaches Ick3, the set pressure holding valve 39c is completely opened at a time T3 at which the pressure of the main pipeline increases further and rises to the pressure Pck3 of the set pressure holding valve 39c. .

At this time, the pressure of 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.

This is because the control signals IFR to IRL of the controller 4 become the proportional solenoids 32S of the proportional pressure control valves 32FR to 32RL and the hydraulic actuators 2FR to 2RL according to the detection signal X of the vehicle position change detector 41. 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 fully 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 stopped at time T5, the hydraulic pump stops, and the pressure in the system pipe is momentarily zero, and the main pipeline pressure control valve 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 at Ick3 and the set pressure holding valve is completely closed at Ick2, the pressure in the main and return lines is cold. It becomes Pn which is a holding pressure.

During the time periods 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 garage holding pressure Pn to maintain the garage holding pressure Pn. do.

When the high maintenance pressure is reached at time T7, the control signal IBY is interrupted from being supplied to the proportional solenoid 31S of the main pipeline pressure control valve 31, and the control signal IBY is interrupted 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 line pressure control valve 31 as shown in FIG. The energization of the signals IFR to IRL is stopped.

When the energization of the main line pressure control valve 31 is stopped at time T0, the main line and the return line are vented, 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 of the main pipe by using the main pipe pressure control valve 31, thereby controlling opening / closing of the set pressure holding valve 39c to prevent vehicle sudden change immediately after engine start / stop and system failure. And the vehicle maintains a constant height during parking, and is performed by a simple structure by the set pressure maintaining valve 39c and the main pipeline pressure control valve 31, and the discharge flow rate of the hydraulic pump 1 becomes zero when the system breaks down. Reduction and noise reduction effect can be achieved.

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, thereby realizing the riding comfort and steering and stability that are not obtained in the conventional shock absorber.

Furthermore, the present invention can be implemented by a simple structure by preventing a sudden change of the vehicle immediately after starting / stopping the engine and maintaining a constant vehicle at the time of parking by a combination of the pressure setting holding valve and the main line pressure control valve.

In addition, by controlling the opening degree of the pressure setting holding valve using the main line pressure control valve, it is possible to realize the riding comfort and control and stability at the same time by a simple structure, and to minimize the energy consumption and noise.

Claims (3)

A hydraulic circuit of an active suspension device for a vehicle is formed, and the hydraulic actuator on the front and rear wheels is controlled to control the movement state of the vehicle while the oil discharged from the variable displacement hydraulic pump 1 is supplied to the cylinder 20 and exhausted. 2: 2FR-2RL); The detection signal X of the vehicle position change detector 41 and the detection signal Y of the abnormal state detector 42 are connected to the hydraulic actuators 2: 2FR to 2RL to control signals IBY of the controller 4. Main line Lm pressure control valve 31 and front / rear side pressure control valves 32FR to 32RL provided with proportional solenoids 32S to control the vehicle position optimally by IFR to IRL; Front wheel side main accumulator (36F), rear wheel side main accumulator (36R) and front and rear wheel pressure control valves (32FR to 32RL) connected to the main line to prevent the sudden change of the garage due to the cylinder chamber pressure change in the actuator. A front wheel return accumulator 38F and a rear wheel return accumulator 38R connected to each other; System failure In order to prevent return pressure abnormality during driving and during riding load and riding number conversion, integrally with the air vent 401 between the main line Lm and the return line Lr of the front wheel valve unit 3F and the rear wheel valve unit 3R. Return pressure abnormality prevention check valve 40 is configured to be connected; The pressure of the pilot pipe line Lp is controlled by the main pipe pressure control valve 31, and the return line Lr, the main pipe line Lm, and the control panel according to the characteristics of the vehicle to which the spring force is adjusted by the pressure is applied. A set pressure holding valve 39c for setting the pressure in the furnace Lc; The pump pulsation absorbing accumulator 10 and the oil tank 5 including a filter are connected to both sides of the variable displacement hydraulic pump 1 which is connected to the system pipeline and the tank pipeline by the hydraulic source, and checks to prevent damage to the filter. In the case where the filter 33 including the valve and the oil cooler 39b are connected, the main line pressure control valve which controls the pressure in the main line to maintain the garage in the event of a system failure and zero the pump discharge flow rate. (31), and the hydraulic pressure circuit of the active suspension device for a vehicle, characterized in that the set pressure holding valve (39c) and the damping orifice (39a) to be opened and closed by pilot pressure control. 2. The flow rate according to claim 1, wherein the flow rate leaking through the fail relief valve is set to zero during normal driving without failure of the swash plate control mechanism, and the pressure in the main pipe and the system pipe becomes the maximum pressure when there is no consumption flow rate of the hydraulic actuator. A hydraulic circuit of an active suspension device for a vehicle, characterized in that the swash plate angle of the variable displacement pump operated by the pressure of the pipe line is zero, so as to reduce the discharge flow rate, thereby improving energy efficiency and reducing noise. The hydraulic circuit of an active suspension device for a vehicle according to claim 1, wherein the main line pressure control valve is used to control the opening degree of the set pressure maintaining valve and to adjust the pilot pressure change rate according to the applied vehicle.