KR960000338B1 - Hydroulic circuit of active suspention for vehicle - Google Patents

Abstract

The hydraulic circuit controls continuously the pressure of hydraulic actuators so that it may check the vibration generated from the irregular running state and improve drive conformability. It comprises the hydraulic actuator(30); a variable hydraulic pump(38) pumping fluid for the actuator(30); a pilot pressure control valve(36) closing the circuit between the actuator(30) and the pump(30); proportional solenoids(36S,20S); a controller(32) controlling the hydraulic pressure based on the signals from a vehicle posture detector(31) and an abnormal state detector(29).

Description

Hydraulic Circuit of Vehicle Active Suspension

1 is a structural diagram of an active suspension by a conventional hydraulic actuator.

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

3 is a graph showing the control pressure change of the cylinder chamber in the hydraulic actuator with respect to the input signal of the proportional pressure control valve.

4 is a graph for explaining the operation of the pilot pressure control valve and the set pressure maintaining valve.

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

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

* Explanation of symbols for main parts of the drawings

1: Pump 3,11,11F, 11R, 13,16,16F, 16R: Accumulator

4,9,34: check valve 6: relief valve

15: Actuator 20FR, 20FL, 20RR, 20RL: Proportional pressure control valve

21: oil cooler 23: oil tank

24: multi-function valve unit 25: control valve unit

26S, 26R, 26P, 26C: Pipe 29: Abnormal State Detector

20FR, 30FL, 30RR, 30RL: Hydraulic Actuator

30A: Sub accumulator 30C: Cylinder chamber

31: vehicle attitude change detector 32: controller

20S, 36S: Proportional solenoid 36: Pilot pressure control valve

37: set pressure maintaining valve

The present invention is to install a proportional pressure control valve in the active suspension system to continuously control the pressure of the hydraulic actuator attached to each wheel to suppress the vibration generated according to the driving state to reduce the change in vehicle attitude, and the ride structure and The present invention relates to a hydraulic circuit of an active suspension device for a vehicle that can simultaneously realize coordination stability.

In general, the suspension of the vehicle is an important mechanism for connecting the axle and the frame (car body) and absorbing the vibration or shock received from the road surface while driving to improve the comfort and safety of the vehicle.

As a part of such a suspension device, there is a shock absorber that controls the free vibration of the chassis spring generated by the road surface to improve ride comfort.

In hydraulic shock absorber operation, the hydraulic actuator is driven to vary the damping force of the vehicle.

Here, the damping force is a resistance force felt when the shock absorber is pulled out, and this damping action absorbs the vibration generated in the spring.

1 is a specific structural diagram of a conventional active suspension device for controlling the motion state of a vehicle by a hydraulic actuator, and is disclosed in Japanese Patent Laid-Open No. 3-42321.

As shown in the drawing, the conventional active suspension device includes a hydraulic pump 1 as a supply source, a control valve unit as a means for controlling the pressure of the actuator 15 and the actuator l5 disposed corresponding to each wheel. 25 and the multifunctional valve unit 24 are provided.

In order to absorb the pulsation of the hydraulic pump (1) as a supply source, a pump pulsation hop accumulator (3) is provided, and between the accumulator (3) and the relief valve (6) for setting the system input, the filter (5) and A check valve 4 for preventing damage to the filter is installed, and the return side configuration is returned to the oil tank 23 through the oil cooler 21 to cool the oil.

The actuator 15 arranged correspondingly to each wheel is composed of a sub-accumulator 13 and an attenuation orifice 14, and the control valve unit 25 connected to the actuator 15 is divided into two front and rear wheels so that the front The pressure of each actuator 15 of the rear wheel is controlled, and a main accumulator 11 is provided on the supply side of the control valve unit 25, and a return accumulator 16 is provided on the return side.

The operation of the conventional active suspension configured as described above will be described.

The oil discharged from the hydraulic pump 1 is set to a system pressure by the relief valve 6, and the oil is supplied to and discharged from the cylinder chamber of the actuator 15 arranged correspondingly to each wheel and operated. The state is controlled.

That is, the vehicle attitude control is possible by adjusting the pressure in the actuator 15.

The multifunction valve unit 24 has a function of maintaining a constant garage control pressure when the engine is stopped and parked, and a soft pressure change function immediately after the engine is started and immediately after the engine is stopped. Function to maintain the control pressure of the garage.

The main pressure reducer 11 compensates for the shortage of supply oil from the hydraulic pump 1 when the actuator 15 needs a large amount of flow momentarily, absorbs the fluctuation of the supply pressure, and maintains the return pressure after the engine stops. During maintenance, 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.

The sub accumulator 13 and the attenuation orifice 14 of the actuator 15 disposed corresponding to each wheel absorb high frequency vibration.

This conventional approach uses hydraulic components that serve a variety of functions to supply and exhaust oil to the actuator.

However, there is a problem in that the vehicle must be designed to be compact because there is not enough free space for mounting a hydraulic component having a large function.

In addition, conventionally, a control valve unit is used by dividing the multifunctional valve unit from the front wheel / rear wheel for controlling the pressure of the actuator of each wheel.

However, the structure of the multifunctional valve unit is complicated, and the use of several valves increases the size and weight of the multifunctional valve unit, thereby limiting the application type, and the flow path is complicated, which limits the mounting space, and prevents vibration by hydraulic pulsation. There were various problems such as causing.

The present invention is to solve the conventional problems as described above, an object of the present invention is to provide a proportional pressure control valve to actively control the state of movement of the vehicle by continuously controlling the pressure of the hydraulic actuator attached to each wheel It is to provide a hydraulic circuit of an active suspension device for a vehicle that can realize ride comfort and steering stability at the same time.

It is another object of the present invention for a vehicle to perform a garage sudden change prevention function immediately after engine start / battery and a system failure and a constant garage maintenance function by parking by a simple structure combining an actual pressure retention valve and a pilot pressure control valve. It is to provide a hydraulic circuit of an active suspension.

Another object of the present invention is a hydraulic circuit of an active suspension for a vehicle to minimize the energy consumption by reducing the flow rate of the flow by the structure that completely closes the pilot pressure control valve during the control, and very small pressure in the return line. To provide.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 6 as follows.

2 is a hydraulic circuit diagram of an active suspension device for a vehicle as a first embodiment of the present invention.

As shown in the drawing, the present invention can be broadly divided into a front wheel valve unit 39F and a rear wheel valve unit 39R.

As the hydraulic source, a variable displacement hydraulic pump 38 and a pump pulsation absorbing accumulator 3 are configured, and an oil tank 23 having a filter and a check valve for preventing damage to the strainer is provided at the input side of the hydraulic pump 38. Is composed.

The hydraulic actuators 30FR, 30FL, 30RR, 30RL are composed of a cylinder chamber 30C, a damping subaccumulator 30A, a piston damping valve 30P, and a body damping valve 30D.

Variable position type hydraulic pump 38, which is the source of hydraulic pressure, and the vehicle attitude change detector 31 and the abnormal state tipping machine to control the pressures of the hydraulic solenoids 30FR, 30FL, 30RR, and 30RL disposed corresponding to each wheel. (29) is comprised.

In accordance with the detection signals (X, Y) of the vehicle attitude change detector 31 and the abnormal state detector 29, the instrument 32 includes a pilot pressure control valve 36 and a proportional pressure control valve 20FR (20FL) (30RR). 20RL controls the proportional actuators 36S and 20S to the optimum vehicle attitude by the control signals IBY (IFR) (IFL) (IRR) (IRL).

The front wheel valve unit 39F includes a strainer 5, a strain relief check valve 4, a relief relief valve 6 for setting the system pressure, and a main check valve 9.

In addition, the front wheel side main accumulator (1F) and front wheel side pressure control valve (20FR) (20FL) are located in front of the front wheel side filter (33F) as a dirt filter, and the return side pipe line (26R) has a front wheel side return shaft. An inlet 16F and an oil cooler 21 include a pilot pressure control valve 36, a set pressure holding valve 37, a check valve 34 for preventing return failure, a vent 34B, and the like.

The rear wheel valve unit 39R has a rear wheel main accumulator 11R for accumulating pressure, and a rear wheel filter 33R as a back surface filtration device in front of the rear wheel pressure control valves 20RR and 20RL. The rear wheel-side return accumulator 16R, a check valve 34 for preventing abnormal return pressure, and a vent 34B are formed at 26R.

Referring to the operation of the active suspension of the present invention configured as described above are as follows.

The oil discharged from the variable displacement hydraulic pump 38, which is the hydraulic source, is supplied to and discharged from the cylinder chamber 30C of the hydraulic actuators 30FR, 30FL, 30RR, and 30RL corresponding to each wheel. To control the state of movement.

The motion state of the vehicle is driven by the proportional solenoid 20S of the proportional pressure control valves 20FR, 20FL, 20RR, and 20RL by the detection signal X of the vehicle attitude change detector 31, In other words, optimal control of posture and stability.

Various functions, such as a constant height maintenance function at the time of system failure, and a sudden height change prevention function immediately after the engine is started and immediately after the engine is stopped, are proportional to the proportional solenoid of the pilot pressure control valve 36 by the detection signal (Y) of the abnormal state detector 29. 36S is driven and performed.

That is, the pilot pressure of the pilot conduit 26P is controlled by the proportional solenoid 36S, and is performed by the set pressure holding valve 37 which switches the opening degree by the pilot pressure.

In addition, when the system breaks down, the return pressure increase prevention function at the time of changing the riding load and the riding number is performed by the check valve 34 for preventing the return pressure abnormality integrally formed with the air vent 34B.

3 is a graph showing the control pressure change of the cylinder chamber in the hydraulic actuator relative to the input signal of the proportional pressure control valve used in FIG.

As shown therein, the hydraulic actuators 30FR and 30FL are applied to the inputs of the control current values IFR, IFL, IRR, and IRL of the proportional pressure control valves 20FR, 20FL, 20RR, and 20RL. It can be seen that the control pressure of the cylinder 30C in 30RR) 30RL changes linearly.

In the present invention, this linear characteristic is used to convert the pressure of the cylinder chamber 30C in the hydraulic actuators 30FR, 30FL, 30RR, 30RL to the proportional pressure control valves 20FR, 20FL, 20RR, 20RL, and 20RL. By changing the control current value IFR (IFL) (IRR) (IRL) and continuously controlling it, it is possible to suppress a change in attitude of the vehicle.

In other words, it is possible to improve the maneuverability by controlling the vehicle's posture during turning, braking and steering while suppressing vibration generated according to driving conditions and keeping the vehicle as horizontal as possible. Alternatively, the vehicle attitude change can be minimized at the time of deceleration, steering and turning, thereby optimizing the movement characteristics of the vehicle, i.e., riding comfort and adjustment stability can be simultaneously realized.

The pilot pressure control valve 36 used in FIG. 2 sets the pressure of the return side pipeline 26R according to the characteristics of the vehicle applied by the set pressure maintaining valve 37 controlled by the pressure of the pilot pipeline 26P. And maintain the garage holding pressure.

That is, according to the pressure of the pilot pipe line 26P controlled by the proportional solenoid 36S, the set pressure holding valve 37 performs opening switching.

However, in the event of a system failure, the pressure in the cylinder chamber 30C in the hydraulic actuators 30FR, 30FL, 30RR, 30RL due to the pressure fluctuations in the return line 26R caused by the switching of the set pressure holding valve 37 is changed. This will change quickly.

The garage sudden change prevention function at this time includes the front wheel side accumulator 11F and the front wheel return accumulator 16F in the front wheel valve unit 39F, and the rear wheel side main accumulator 11R and the rear wheel in the rear wheel valve unit 39F. 16 R of side return accumulators, and the check valve 34 for preventing an abnormal return pressure.

Here, when the pressure drops due to the small flow loss, the front wheel side accumulator 11F and the front wheel return condenser 16F, and the rear wheel main accumulator 11R and the rear wheel return accumulator 16R are accumulated. Oil is supplied to prevent pressure drop.

In the hydraulic circuit of the active suspension, in general, during the engine rotation, that is, during normal control, the supply pressure should be maintained and the pressure control function, and the return pressure should be zero to improve the efficiency.

The hydraulic circuit of the present invention maintains a smooth garage pressure when a system failure occurs during normal control, and the discharge flow rate supplied from the variable displacement hydraulic pump 38 is easily restored to improve energy efficiency. .

4 is a graph for explaining the operation of the pilot pressure control valve 36 and the set pressure maintaining valve 37 used in FIG.

As shown therein, the pilot pressure L2 of the pilot pipe line 26P is changed in accordance with the control signal IBY applied to the solenoid 36S, and the set pressure is maintained in accordance with the pressure change of the pilot path 26P. The valve 37 opens and closes.

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

When the engine is started at time T0, the pump discharge pressure L3 rises to the pressure P2 of the relief valve 6.

Immediately after the engine is started, the pressure of the supply-side pipe line 26S is increased by the operation of the hydraulic pimp 38, so that the height of the garage is changed by the pressure change of the cylinder chamber 30S in the hydraulic actuators 30FR, 30FL, 30RR, 30RL. In order to prevent this, the control signal IBY applied to the proportional solenoid 365 is gradually increased from T1 time to T2 time.

When the control signal IBY applied to the proportional solenoid 36S is I _c , that is, at time T2, the pressure L2 of the pilot pipe 26P gradually rises at P3, and the set pressure maintaining valve 37 starts to open. , At the time T3 when the control signal IBY of the proportional solenoid 36S is I _{p, that} is, when the pressure L2 of the pilot pipe 26P is P _{p, the} set pressure maintaining valve 37 is fully opened and the return pressure is maintained. Is kept at Pl.

At the same time, the proportional pressure control valves 20FR (20FL) and 20RR are controlled by the control signals IFR (IFL) (IRR) (IRL) of the controller 32 according to the detection signal X of the vehicle attitude change detector 31. The proportional solenoid 20S of 20RL is controlled, and the pressure of the cylinder chamber 30C in the hydraulic actuators 30FR, 30FL, 30RR, 30RL can be controlled to control the vehicle attitude.

That is, normal control is performed at time T4-T5, and during normal control, the pilot pressure control valve 36 is completely closed (i.e., the pilot pressure is set to Pmax) to reduce the return flow rate, that is, the consumption flow rate, and the return side. The pressure of the conduit 26R is set at around 0 pressure to minimize energy consumption.

On the contrary, if a system failure occurs in T5 time, the control signal IBY of the non-solenoid 36S is short-circuited and becomes 0, and the pressure of the pilot pipe 26P is reduced from T5 time.

The set pressure maintaining valve 37 starts to close at the time T6 when the pilot pressure L2 becomes P _{p and} is completely closed at the time T7 so that it is maintained at the garage holding pressure P3 and discharged supplied by the hydraulic pump 38. The flow rate is relief.

When the engine stops at the time T8, the pump discharge pressure L3 decreases to zero due to the stop of the hydraulic pump 38, but the pressure L2 of the pilot pipeline 26P is set by the set pressure maintaining valve 37. It is maintained at the garage holding pressure P3.

Therefore, the garage sudden change prevention function immediately after the engine start / stop and the constant garage maintenance function at the time of system failure and parking can be performed by the simple structures of the set pressure maintaining valve 37 and the pilot pressure control valve 36.

As another embodiment of the present invention, the hydraulic circuit of FIGS. 5 and 6 may be proposed.

5 is a hydraulic circuit diagram of an active suspension device for a vehicle according to a second embodiment of the present invention.

As shown in this figure, the present embodiment is configured in the same manner as in the first embodiment shown in FIG. 2, but only the pilot pressure control valve 36 is installed by branching the supply side flow path 26S to set the pressure maintaining valve. Opening and closing of (37) was controlled.

In addition, when a system failure occurs during normal control, the supply-side flow path 26S is prevented from increasing the pressure in the supply-side pipe line 26S due to the pimp discharge flow rate supplied from the variable-capacity hydraulic pimp 38. The main check valve 9, which uses a spring greater than the pressure of), is configured to operate by the check pilot conduit 26C.

6 is a hydraulic circuit diagram of an active suspension device for a vehicle according to a third embodiment of the present invention.

As shown in this figure, the present embodiment is configured in the same manner as in the first embodiment shown in FIG. 2, but only the pilot pressure control valve 36 is provided on the return side of the relief valve 6, and the relief The if valve 36 was operated by the pressure of the supply side pipeline 26S and the pressure of the pilot pipeline 26P controlled by the pilot pressure control valve 36.

Thus, the relief valve 6 and the pilot pressure control valve 36 are integrated to reduce the hydraulic circuit size and reduce the flow rate of the relief valve 6 for efficiency.

According to the hydraulic circuit of this embodiment, the supply pressure is maintained and the pressure control function is maintained during engine rotation, that is, during normal control, and the return pressure is zero for improving the efficiency.

In addition, when a failure occurs in the system, a smooth garage pressure is maintained, and the pump discharge flow rate supplied from the variable displacement hydraulic pump 38 is easily restored to improve energy efficiency.

As described above, the present invention can realize the riding comfort and the steering stability by controlling the pressure of the hydraulic actuator attached to each wheel to actively control the state of movement of the vehicle.

In particular, the simple structure that combines the set pressure maintaining valve and the pressure control valve can perform the sudden change prevention of the garage immediately after starting / stopping the engine, the system failure, and the constant garage maintenance during parking.

In addition, it is possible to reduce the flow rate by reducing the return flow rate by the structure that completely closes the pilot pressure control valve during normal control, and has the effect of minimizing the energy consumption by making the pressure in the return line close to zero.

Claims (1)

Hydraulic actuator (30FR) installed on each wheel and changing the state of the vehicle by the pressure change of the inner cylinder chamber, variable hydraulic pump (38), and the hydraulic actuator (30FR) variable to pull out the fluid with the hydraulic actuator A pilot pressure control valve 36 installed between the hydraulic pumps 38 to open and close the flow path, a proportional pressure control valve 20FR provided between the pilot pressure control valve 36 and the hydraulic actuator 30FR to open and close the flow path, Receives a signal from the proportional solenoid (36S, 20S), the vehicle attitude change detector 31 and the abnormal state detector 29 provided on one side of the pilot pressure control valve 36 and the proportional pressure control valve 20FR, respectively. A controller 32 for controlling the proportional solenoids 36S and 20S to control oil pressure so as to be appropriate to the situation, a pilot pipeline 26P bypassed from the pilot pressure control valve 36, and the variable hydraulic pump 38; Proportional pressure control valve (20FR) A return side pipeline 26R connected to the pilot pipeline 26P and connected to one side of the pilot pipeline 26P to close the pipeline 26R when an abnormal state of the vehicle occurs and when the vehicle starts and stops. A pressure accumulator 16F provided between the set pressure maintaining valve 37 and the pipe line 26R and the proportional pressure control valve 20FR to compensate for the hydraulic pressure returned from the proportional pressure control valve 20FR to prevent cavitation; A hydraulic circuit of an active suspension device for a vehicle, comprising: a check valve 34 for communicating the inlet side and the return side of the proportional pressure control valve 20FR to compensate for the oil pressure to the inlet side when the return side pressure increases. .