KR960000336B1 - Active-suspension for vehicle - Google Patents

Abstract

The apparatus for reducing running vibration and keeping horizontal state stable to increase comfort, includes proportional pressure control valves(20FR-20RL) controlling pressure of actuators(30FR-30RL) with detection signal(X) of a detector(31) detecting state variation, a pilot pressure control valve(36) preventing rapid variation of vehicle height caused at engine start and keeping vehicle height constant in case of system failure, a preset pressure maintaining valve(37) keeping pressure of oil return line constant, and a relief valve(6) setting system pressure.

Description

Vehicle Active Suspension

1 is a hydraulic circuit diagram of a conventional vehicle active suspension.

2 is a hydraulic circuit diagram of an active suspension device according to the present invention.

3 is a schematic cross-sectional view of a proportional pressure control valve applied to the present invention.

4 is a schematic cross-sectional view of a pilot pressure control valve applied to the present invention.

5 is a schematic cross-sectional view of a relief valve applied to the present invention.

6 is a schematic cross-sectional view of a set pressure maintaining valve applied to the present invention.

7 is an input signal band control pressure diagram of a proportional pressure control valve according to the present invention.

8 is an operation diagram of the pilot input control valve and the set pressure maintaining valve according to the present invention.

* Explanation of symbols for main parts of the drawings

265: supply side pipeline 26R: return side pipeline

26P: Pilot Pipe 29: Abnormal State Detector

30FR, 30FL, 30RR, 30RL: Hydraulic Actuator 32: Controller

31: Vehicle position change detector 34: Return pressure check valve

34B: Vent 36: Pilot pressure control valve

365: proportional solenoid for pilot pressure control valve 38: variable displacement hydraulic pump

37: Set pressure maintaining valve 39F: Front wheel valve unit

39R: rear wheel side valve unit 40: valve body

41: spool 42: spool sleeve

44: return spring adjustment screw 47: pilot orifice

48: return orifice 49: plunger

50: poppet 51: supply orifice housing

52: supply orifice 53: control orifice

54: poppet sleeve 55F: return room

55P: Pilot room 55C: Pressure chamber

56: poppet pot 60C: poppet chamber

61: spring regulator 62: pilot valve

65: pilot valve seat 71: pilot spool sleeve

72: fixed disk 73: cracking pressure adjusting screw

74: sleeve adjustment screw 76: pilot spool

77: pylon poppet Ll: return pressure line

L2: Pilot Pressure Diagram

The present invention relates to an active suspension device for a vehicle, and more particularly, a proportional pressure control valve is mounted on a vehicle suspension device so that the pressure of each hydraulic actuator can be continuously controlled to be suitable for various conditions of starting, stopping, and driving a vehicle. Accordingly, the present invention relates to an active suspension device for a vehicle which suppresses vibration generated according to a driving state and maintains a horizontal level of a vehicle to simultaneously improve ride comfort and maneuverability.

The conventional active suspension device (Japanese Patent Application Laid-Open No. 3-42321) has an actuator 15 and an actuator (15) arranged correspondingly to a hydraulic pump (1) and each wheel as a fluid supply source, as shown in FIG. It consists of a control valve unit 25 for controlling the pressure of 15) and a pressure holding unit 24 for regulating and maintaining the pressure. The hydraulic pump (1) includes a filter (5) and a filter damage prevention check valve (4) between a pimp pulsation absorption accumulator (3) and a relief valve (6) for setting a system pressure to absorb hydraulic pulsation. Is installed, the oil tank 23 for returning oil through the oil cooler 21 for cooling the oil is configured on the return side. The actuator 15 corresponding to each wheel is comprised by the sub accumulator 13 and the damping orifice 14, and the said control valve unit 25 is divided into two front and rear wheels. The front wheel side is composed of two left and right control valves 20 to control the pressure of the actuator 15, the main accumulator 11 on the supply side of the control valve 20, the return accumulator 16 and the damping orifice (on the return side) 19) 17 are constructed. The pressure holding unit 24 is provided between the orifice 7 and the integral flow control valve 8 for preventing the high sudden change immediately after the engine is started, and for preventing the high sudden change and maintaining a constant height when a failure occurs in the electrical system. The safety valve 10, the pressure holding check valve 18 and the relief valve 6 are installed.

The conventional active suspension device configured as described above controls the state of movement of the vehicle by supplying and evacuating the cylinder chamber of the actuator 15 in which oil discharged from the hydraulic pump 1 is disposed corresponding to each wheel. In the flow path 265 leading to the actuator 15, a pressure control valve 20, which is a proportional solenoid valve, is disposed, and the pressure control valve 20 supplies and discharges hydraulic pressure to the actuator 15 for example. On the basis of the detection output X of the posture change detector 28, the control outputs IFR and IFR of the control device 27 are supplied to the proportional solenoid 20S of the pressure control valve 20 to supply the actuator 15 It is possible to control the vehicle posture by adjusting the pressure inside. The relief valve 6 of the pressure holding unit 24 for adjusting and maintaining the pressure maintains the system pressure at a constant pressure, and immediately after the engine is started, the high-speed change prevention is driven by the orifice 7 and the control signal IFS. The flow control valve 8 composed of the on / off solenoid 8S performs its function, and is driven by the on / off solenoid 10S for preventing the sudden change of the vehicle and maintaining a constant height when a failure occurs in the electrical system. By adjusting the pilot pressure of the fail-safe valve 10 to be opened and closed the pressure holding check valve 18 performs its function. The high level change prevention by the return pressure change after engine stop is performed by the attenuation orifice 17, the return accumulator 16, and the main accumulator 11 by opening-change of the pressure holding check valve 18. As shown in FIG. The main accumulator (11) to compensate for the shortage of the supply oil from the hydraulic pump (1) and to absorb the fluctuations in the supply pressure when a large amount of flow in the actuator (15) is required instantaneously, the pressure maintenance check valve ( By the operation of 18), the return pressure is kept constant so that the drop in the return pressure due to leakage is softened to prevent sudden changes in the garage.

The return accumulator 16 absorbs the pulsation of the return hydraulic pressure, and the sub accumulator 13 and the attenuation orifice 14 of the actuator 15 disposed corresponding to each wheel absorb the high frequency vibration. The conventional active suspension device operating in this way is to control the state of movement of the vehicle by supplying and evacuating the oil discharged from the hydraulic pump 1 to the cylinder chamber of the actuator 15 corresponding to each wheel. Hydraulic components are used, but there is not enough space in the vehicle to install various hydraulic components. Due to this, the parts have to be compactly designed. In the conventional apparatus, the front wheel / rear wheel is divided into a pressure control unit 25 in order to control the pressure between the pressure holding part 24 and the actuator 15 of each wheel. Designed. In particular, in order to prevent the rapid change immediately after the engine starts, the two-port 2-switch valve using the on / off solenoid 8S and the orifice 7 was used. ), And gradually increases the system pressure through the orifice (7) to prevent the high profile change. When an abnormality occurs in the electric system, the main flow path is switched by the four-port two-switching valve 10 using the on / off solenoid 10S, and the constant pressure holding valve 18 on the return side performs constant maintenance. It is composed of a system.

However, the flow rate control valve 8 using the on / off solenoid 8S and the failure stabilization valve 10 using the on / off solenoid 105S have a complicated structure of the valve itself, which increases the number of parts and makes machining difficult.

In addition, since two valves using on / off solenoids are direct-acting spool valves, a large force solenoid must be used to control them. Due to this, the size of the pressure holding part 24 becomes large and the weight becomes heavy due to the increase of the solenoid, thereby limiting the application type, and the flow path is complicated, thereby limiting the mounting space, and causing vibration by hydraulic pulsation. have.

In addition, the attenuation orifice 19 in the return side pipe 26R has a problem in that energy loss is largely generated due to the increase in the return pressure during normal control.

The present invention has been made to solve the above problems, the object of the present invention is to equip the suspension device which is installed to improve the ride comfort and stability of the vehicle by continuously controlling the pressure of each hydraulic actuator by In order to suppress the vibration generated according to the driving state and to maintain the level of the vehicle to improve the riding comfort, another purpose is to control the vehicle posture by continuously controlling the pressure of each hydraulic actuator during turning, braking and steering of the vehicle. And to improve the controllability and stability.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a hydraulic circuit diagram of an active suspension device for a vehicle according to the present invention, wherein a hydraulic pump 38 for supplying fluid is provided with a variable displacement hydraulic pump 38 and a pump pulsation absorption accumulator 3, and the hydraulic pump 38 ) Is composed of a filter (5) and an oil tank (23) having a check valve (5a) for preventing damage of the filter (5).

The hydraulic actuator (30FR-3ORL) corresponding to each wheel is composed of a cylinder (30C), a coil spring (30S), a damping sub-accumulator (30A), a piston damping valve (30P), and a body damping valve (30D). . In order to control the pressure of the variable displacement hydraulic pump 38 and the hydraulic actuator 30FR-30RL corresponding to each wheel, the detection detected by the vehicle position change detector 31 and the abnormal state detector 29 is performed. The controller 32 receives and analyzes the signals X and Y to control the proportional solenoids 36S and 20S of the pilot pressure control valve 36 and the proportional pressure control valve 20FR-20RL.

The filter 5, the check valve 4 for preventing damage to the filter and the relief valve 6 for setting the system pressure are provided with a front wheel valve unit 39F and a rear wheel valve unit 39R. 39F is a contaminant filtering device in front of the main check valve 9, the front wheel main accumulator l1F and the front wheel pressure control valve 20FR, 20FL for accumulating the front wheel filter 33F and the return pipe. A front wheel return accumulator (16F) and an oil cooler (21) are formed in the 26R, and the pilot pressure control valve 36, the set pressure holding valve 37, the return pressure abnormality prevention valve 34, and the vent 34B are provided. It consists of.

The rear wheel valve unit 39R has a rear wheel filter 33R and a return pipe 26R as contaminant filtration devices in front of the rear wheel main pressure accumulator 11R and the rear wheel pressure control valve 20RR and 20RL for accumulating pressure. ) Is composed of a rear wheel return accumulator 16R, a return pressure abnormality check valve 34 and a vent 34B.

3 is a schematic cross-sectional view of a proportional pressure control valve applied to the present invention, in order to control the pressure of the hydraulic actuator 30FR-30RL disposed corresponding to each wheel, the proportional pressure control valve 20FR-20RL is a valve body ( A main valve and a proportional solenoid composed of a spool 41 and a spool housing sleeve 42 and a feedback orifice 46, a feedback spring 45, a feedback spring adjustment screw 44, and a control orifice 53. 20S and the poppet 50, the poppet housing, the poppet sleeve 54, the supply orifice 52 and the supply orifice housing 51, the pilot orifice 47 and the return orifice 48, It has various functions such as maintaining a constant garage, preventing a sudden change of the vehicle immediately after starting the engine and immediately after stopping the engine.

5 is a schematic cross-sectional view of a relief valve according to the present invention, wherein the relief valve 6 is a direct acting valve body 60, a pilot valve 62 for adjusting the opening degree, and a direct acting relief valve. Pilot valve seat 65 having poppet chamber 60C to alleviate the chattering phenomenon which is likely to occur in the < RTI ID = 0.0 >, < / RTI > adjustment spring 66 for setting pressure and spring regulator 61 for adjusting relief pressure for adjusting relief pressure. The pressure in the system is maintained at the set pressure.

6 is a schematic cross-sectional view of the set pressure retaining valve applied to the present invention, wherein the set pressure holding valve 37 opens and closes the pilot spool 76 and hydraulic pressure to open and close the pilot poppet 77 according to the pressure of the pilot pipe 26P. Oil tank side pipe line 26t from the fixed disk 72, the pilot splice sleeve 71 bearing the housing of the pilot spool 76, and the return side pipe line 26R Pilot poppet (77), coil spring (75), cracking pressure adjusting screw (73) for adjusting cracking pressure, and sleeve fixing screw (74) for fixing pilot spool sleeve (71). do.

Referring to the effects of the present invention configured as described above are as follows. The oil discharged from the variable displacement hydraulic pump 38 as the hydraulic source is supplied to and discharged from the cylinder 30C of the hydraulic actuator 30FR-3ORL correspondingly disposed on each wheel to control the movement state of the vehicle. When the vehicle attitude change detector 31 sends the detection signal X to the controller 32, the controller controls the proportional solenoid 20S of the proportional pressure control valve 20FR-2ORL, that is, the vehicle's movement state. Optimal control of posture and stability.

Various functions, such as maintaining a constant height due to a system failure and preventing a sudden change of the vehicle immediately after the engine starts and immediately after the engine stops, receive the detection signal (Y) of the abnormal state detector 29 from the controller and proportionately proportionate to the pilot pressure control valve 36. The solenoid 36S is controlled to control the pilot pressure of the pilot pipe 26P. That is, the function is performed by the set pressure holding valve 37 which switches the opening degree by the pilot pressure, and the prevention of the return pressure rise when the system breaks down and when the riding load and the number of passengers is changed is integrated with the air vent 34B for air discharge. It is performed by the return pressure abnormality prevention check valve 34 composed of.

In detail, the vehicle should be able to move stably even if the system breaks down. The proportional pressure control valve 20 is controlled because the load change of the road while carrying the vehicle to the workshop due to a failure of the system acts as a load on the hydraulic actuator.

At this time, if there is no means for communicating the system line and the return line, the pressure in the system line is lowered, and the pressure in the return line continues to rise. Therefore, if the check valve 34, which is a non-return valve, is connected by connecting the system line and the return line, the pressure on the return line flows into the system line over the force of the check valve, so that the instability of the vehicle due to unbalance of the line is eliminated and This is to be improved. Since the difference between the ride load and the ride number also acts as a load on the hydraulic actuator 30, the proportional pressure control valve 20 is controlled to cause the above-described action.

In the steady state, the proportional pressure control valve 20FR-2ORL which optimally controls the movement state of the vehicle, that is, the posture and the stability, as shown in FIG. 3, is supplied with oil by the variable hydraulic pump 38. The silver is introduced into the pylon chamber 55P through the supply orifice 52 and the pilot orifice 47, and the introduced oil is returned to the tank through the poppet port 56 formed by the poppet 50. At this time, when the left and right chambers of the spool 41, that is, the pressures of the pilot chamber 55P and the return chamber 55F are equal, the spool 41 is maintained in the neutral position by the return spring 45. If the current I, which is a control signal of the proportional solenoid 20S, is increased, a force proportional to the amount of current I is generated by the plunger 49, thereby pushing the poppet 50 to increase the pressure of the pilot chamber 55P and poppet. Reference numeral 50 stops where the force acting by the proportional solenoid 20S and the force acting by the pilot chamber 55P pressure are balanced. Therefore, the pressure of the pilot chamber 55P is changed in proportion to the amount of current I supplied to the proportional solenoid 20S. When the pressure rises, the flow rate flows through the pilot orifice 47, and the pressure of the compression chamber 55C is increased. That is, the control pressure rises.

On the other hand, when the pressure in the compression chamber 55C rises, the flow rate flows into the return chamber 55F through the feedback orifice 46, thereby increasing the pressure in the room, and the pressure is higher than the pressure in the pilot chamber 55P. When the spool 41 is pushed to the left side, the spool 41 is pushed out to the flow basin oil tank 23 through the return side pipe 26R to reduce the pressure in the compression chamber 55C. Through this process, the pressure in the compression chamber 55C becomes equal to the pressure in the pilot chamber 55P.

Therefore, the pressure of the compression chamber 55C is adjusted in proportion to the current amount I of the proportional solenoid 20S, and this pressure controls the pressure of the hydraulic actuator 30FR-3ORL of the active suspension. The feedback function of the proportional pressure control valve 20FR-2ORL, which senses and maintains the pressure in the compression chamber 55C, is controlled even when the current I of the proportional solenoid 20S is fixed to a certain value. Even when the signal I is constant, the pressure of the compression chamber 55C is controlled.

Therefore, although the pressure of the hydraulic actuator 30FR-3ORL is not controlled by the control device by the proportional solenoid 20S, the feedback orifice 46 in the proportional pressure control valve 20FR-2ORL is mechanically used for the compression chamber 55C. It is possible to control the pressure continuously.

The control range of the compression chamber 55C is increased by the feedback function of the proportional pressure control valve 20FR-2ORL, so that a ride comfort control can be performed up to a high frequency region. On the other hand, in order to maintain a constant height due to a system failure, and to prevent a sudden change of the vehicle immediately after the engine starts and immediately after the engine stops, the detection signal (Y) of the abnormal state detector 29 is transmitted from the controller to the proportional solenoid valve of the pilot pressure control valve 36 ( 36S) to control the pilot pressure of the pilot pipe 26P. That is, the function is performed by the set pressure holding valve 37 which switches the opening degree by the pilot pressure, and the prevention of the rise of the return pressure at the time of system breakdown during traveling, riding load, and riding personnel conversion is provided for the air vent 3B. It is to be performed by the return pressure abnormality prevention check valve 34 integrally formed with.

As shown in FIG. 4, the pilot pressure control valve 36 has a return side pipe line 26R in accordance with the characteristics of the vehicle applied by the set pressure holding valve 37 which is adjusted by the pressure of the pilot chamber 55P. The vehicle holding pressure is maintained by setting the pressure of) to a constant pressure. That is, the opening degree switching of the set pressure holding valve 37 is performed by the pressure of the pilot chamber 55P controlled by the proportional solenoid 36S.

In the event of a system failure, it is possible to prevent the rapid change of vehicle height due to the pressure change in the cylinder chamber 30C in the hydraulic actuator 30FR-3ORL due to the pressure change in the return side pipe 26R caused by the opening switching of the set pressure holding valve 37. Front wheel main accumulator (11F) in the unit (39F), front wheel return accumulator (16F) and rear wheel main accumulator (11R) in the rear wheel valve unit (39R), rear wheel return accumulator (16R), and return pressure. It is made by the abnormality check valve 34. At this time, the pressure drop due to the small flow loss is reduced by the front wheel main accumulator (11F), the front wheel return accumulator (16F), the rear wheel main accumulator (11R), and the rear wheel return accumulator (16R). The supply prevents the pressure increase caused by the micro flow loss. As shown in FIG. 5, the relief valve 6 which maintains the pressure of the system at the set pressure has a pressure less than the desired relief pressure by using the spring regulator 61 as the pressure of the oil coming from the supply side pipe 26S. To keep. At this time, when the pressure of the oil exceeds the set relief pressure, the pilot valve bead 65 is pushed by the hydraulic pressure, so the oil passes through the poppet chamber 60C to the oil tank side pipe line 26t. Therefore, the poppet chamber 60c prevents chattering due to the flow rate and uses the flow force of the oil to maximize the response of the relief valve.

The pilot pressure in the pilot pipe line 26P is controlled by the proportional solenoid 36S of the pilot pressure control valve 36, and the set pressure holding valve 37 for switching the opening degree by the pilot pressure is the return side pipe line 26R. The return amount to the oil tank side pipe line 26t is determined. When the pressure of the pilot pipe line 26p is greater than the force of the coil spring 75, the toll is opened, and the oil tank side pipe (from the return side pipe line 26R) The oil returns to 26t), and when the pressure of the return side pipeline 26p and the pilot pipeline 26p exceeds the cracking pressure which is the set pressure of the coil spring 75, the oil can be easily returned, and the return side pipeline 26p and If the pressure in the pilot pipe 26p is lower than the cracking pressure which is the set pressure of the loule spring 75, the return flow path is closed and maintained at the set pressure. That is, when the system malfunctions and the engine stops, the return flow path is closed and maintained at the set high hydraulic pressure. During normal operation, the flow path is always opened by the pilot pipe line 26p, so that the flow path is easily returned to save energy. Therefore, during the normal operation, the set pressure holding valve 37 is completely opened so that oil can be easily returned to the oil tank 23, so that the flow rate supplied from the pump is relief at low pressure, thereby avoiding energy reduction and noise reduction effect.

7 is a diagram showing a change in the control pressure with respect to the input signal of the proportional pressure control valve applied to the present invention, that is, a hydraulic actuator for the input of the control current value IFR-IRL of the proportional pressure control valve 20FR-20RL. It can be seen that the control pressure change of the cylinder chamber 30C in 30FR-30RL changes linearly.

Accordingly, the vehicle attitude is controlled by continuously controlling the pressure of the cylinder chamber 30C in the hydraulic actuator 30FR-30RL by the pressure of the front wheel control value IFR-IRL of the proportional pressure control valve 20FR-20RL. Riding and adjustment stability that optimizes the vehicle's movement characteristics by minimizing the change in posture during turning, braking and steering by keeping the vehicle as horizontal as possible by suppressing the vibration generated according to the change in driving conditions. It can be realized at the same time.

8 is a diagram explaining the operation of the pilot pressure control valve and the set pressure holding valve applied to the present invention, wherein the pilot pressure diagram L2 of the pilot pipe 26P is applied to the control signal I applied to the proportional solenoid 36S. Accordingly, the pressure of the pilot pipe line 26P changes, and the set pressure holding valve 37 opens and closes according to the pressure change of the pilot pipe line 26P.

When the engine is stopped (0-T0), the pump discharge pressure L3 is zero, and the pilot pressure L2 and the return pressure () are operated by the operation of the pilot pressure control valve 36 and the set pressure holding valve 37. Ll) is maintained at the garage holding pressure P3.

When the engine is started at time T0, the pump discharge pressure 13 is released to the low pressure Pl because the flow path of the pilot pressure control valve 36 is completely open. Immediately after the engine is started, up to T ₄ hours due to an increase in the pressure of the supply side pipe 26S caused by the operation of the hydraulic pump 38, i.e., to prevent the rapid change due to the pressure change of the cylinder chamber 30S in the hydraulic actuator 30FR-30RL. The control signal IBY is gradually increased to the proportional solenoid 36S from the time T1.

As the control signal IBY increases, the pressure of the supply side pipe 26S gradually rises to the set pressure of the relief valve 6, and when the control signal IBY is Ic to the proportional solenoid 36S, i.e., time pressure wave alreot pipe (26P) in the T ₂ is a garage gradually raised in keeping the pressure (P3), and the set pressure holding valve 37 is started by, a control signal (IBY) to the proportional solenoid (36S) I _p when open At the time T ₃ , that is, at the pressure P _p of the pilot pipe 26P, the set pressure holding valve 37 is completely opened and the return pressure is maintained at the pressure of Pl, and the vehicle attitude change detector 31 is The cylinder chamber in the hydraulic actuator 30FR-30RL is controlled by controlling the proportional solenoid 20S of the proportional pressure control valve 20FR-20RL by the control signal IFR-lRL of the controller 32 by the detection signal X. The vehicle attitude is controlled by controlling the pressure of 30C). That is, at time T ₄ -T ₅ , normal control is performed, and during normal control, the pilot pressure control valve 36 is completely closed (that is, the pilot pressure Pmax north air flow rate of the pilot side pipe 26P is reduced to reduce the holding flow rate. The energy consumption is minimized by reducing the pressure in the return side pipe 26R near zero pressure.

On the contrary, if a system failure occurs at time T ₅ and the control signal IBY is shorted to zero by proportional solenoid 36S, the pilot pressure control valve 36 is completely opened, so the pressure in the supply side pipe 26S is low. Since it is relief at low pressure, it can reduce energy and reduce noise. From time T ₅ , the pressure of pilot side pipe 26P decreases gradually, and pilot pressure L2 is set pressure maintaining valve at pressure P _p, that is, time T ₆ . 37 starts to close and is completely closed at time T7 to maintain the garage holding pressure P3, and the discharge flow rate supplied by the hydraulic jump 38 is reliefd to low pressure.

When the engine stops at time T8, the pump discharge pressure L3 decreases to zero by the stop of the hydraulic pump 38, but the pressure in the pilot pipe 26P is reduced by the set pressure holding valve 37 to the garage holding pressure P3. ) Will be maintained.

As described above, the present invention controls the pressure of the hydraulic actuator attached to each wheel by the set pressure holding valve and the pilot pressure control valve, thereby preventing the vehicle from suddenly shifting immediately after starting / stopping the engine and system failure. It is possible to maintain a constant height when parking and parking, and to get a comfortable ride and adjustment stability. Also, by closing the pilot pressure control valve completely during normal control, the return flow is reduced, the consumption flow is reduced, and the pressure in the return pipe is near zero pressure. The energy consumption can be minimized, and the set pressure holding valve is fully opened during normal operation, so that oil can easily return to the oil tank, and when the system breaks down or the engine stops, it is set to the garage holding pressure smoothly. Since the pressure control valve is fully open, the flow rate from the pump Because standing relief will be provided to the effect that could seek energy reduction and noise reduction.

Claims (7)

Proportional pressure control valve (20FR-20RL) for controlling the movement state of the vehicle by controlling the pressure by the detection signal (X) output from the vehicle position change detector (31) to the hydraulic actuator (30FR-30RL) disposed corresponding to each wheel. And the pressure of the proportional pressure control valve (20FR-20RL) by the detection signal (Y) output from the vehicle abnormal state detector (29) to maintain a constant height due to a system failure and to prevent a sudden change of the vehicle immediately after the engine starts. The pilot pressure control valve 36, the set pressure holding valve 37 for maintaining the pressure at the set pressure in the return side pipeline by the pilot pressure control valve 36, and the relief valve 6 for setting the system pressure. Active suspension device for a vehicle, characterized in that consisting of). 2. The system of claim 1, wherein the pilot pressure control valve (36) is closed to maintain a constant height at the time of preventing a sudden change of the vehicle immediately after starting / stopping the engine and maintaining a constant height, thereby maintaining the pressure in the return side pipe at zero pressure, and causing a system failure. An active suspension device for a vehicle, characterized in that the pilot pressure control valve is fully opened even during driving so that the flow rate supplied from the pump is released at low pressure, thereby reducing energy and reducing noise. The pressure regulating valve (37) opened and closed by the pilot pressure control valve (36) when the system breaks down, and a check valve (34) for preventing the return pressure rise due to the difference between the riding load and the number of passengers. Active suspension device for a vehicle, characterized in that. The proportional pressure control valve (20FR-20RL) according to claim 1, wherein the proportional pressure control valve (20FR-20RL) has a spool (41) and a return orifice (46), a return spring (45) and a spool housing (41) and a spool housing in the valve body (40). Main spring and proportional solenoid 205, poppet 50, poppet housing 54, supply orifice piece 52, and supply orifice consisting of a return spring adjustment screw 44, a control orifice 53 An active suspension device for a vehicle, comprising a housing (51), a pilot orifice (47) and a return orifice (48). The proportional solenoid 20S, the poppet 50, and the poppet housing 54 of the pilot pressure control valve 36 excluding the main valve from the proportional pressure control valve 20FR-20RL. And a supply orifice (52) and a supply orifice housing (51), a pilot orifice (47) and a return orifice (48). The method according to claim 1, wherein the relief valve (6) is a direct acting valve body 60, the pilot valve 62 for adjusting the opening degree, the chattering phenomenon that is likely to occur in the actuated relief valve (6) And a pilot valve seat 65 having a poppet chamber 60C to relieve pressure, an adjustment spring 66 for setting pressure, and a spring regulator 61 for adjusting the relief pressure for adjusting the relief pressure. Active suspension device for the vehicle. According to claim 1, wherein the set pressure holding valve 37 is a movement range of the pilot spool 76 for opening and closing the pilot poppet 77 and the hydraulic pressure of the pilot spool 76 in accordance with the pressure of the pilot pipe (26P) Pilot disks 77 for opening / closing the oil tank side conduits 26t from the return side conduits 26r and the pilot spool sleeves 71 serving as the housings of the fixed disk 72, the pilot spool 76 to be confined. And a coil spring (75), a cracking pressure adjusting screw (73) for adjusting the cracking pressure, and a slide fixing screw (74) for fixing the pilot spool sleeve (71).