JP2907290B2 - Active suspension - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention has a fluid pressure actuator interposed between a vehicle body and each wheel, and controls a pressure in a pressure chamber of the fluid actuator by a control valve such as a pressure control valve. By controlling the vehicle height,
The present invention relates to an improvement of an active suspension device that controls a change in attitude of a vehicle such as a roll and a pitch.

[Conventional technology]

As a conventional active suspension, JP-A-63-21
There is one described in 9408.

In this conventional example, in an active suspension, a fluid check means is provided in a line pressure pipe between a pressure control valve and a hydraulic supply device, and a return pipe is provided only when the output of the hydraulic supply device falls below a predetermined pressure. It has a configuration in which fluid closing means for preventing passage of fluid and pressure adjusting means for maintaining the pressure on the upstream side of the fluid closing means at a predetermined value are interposed in parallel. When the vehicle speed decreases, a sudden change in vehicle height can be prevented.

[Problems to be solved by the invention]

However, in the above-mentioned conventional active suspension, when the hydraulic pressure supply device is stopped and its output drops below a predetermined pressure, the fluid closing means prevents the passage of the fluid, so that the pressure control valve and The hydraulic control system including the hydraulic cylinder can be sealed at the set pressure of the fluid closing means.For example, the set pressure of the fluid closing means is set to the pressure required for the vehicle to maintain the reference vehicle height by the hydraulic cylinder at the standard loading weight. When set, when the weight of the vehicle occupant and the load exceeds the standard load weight, the pressure of the hydraulic cylinder exceeds the set pressure of the fluid closing means. If the pressure of the vehicle drops to the set pressure of the fluid closing means, the vehicle height decreases, and the weight of the vehicle occupant and the load is less than the standard load weight. In other words, the pressure of the hydraulic cylinder is lower than the set pressure of the fluid closing means, and when the hydraulic supply device stops, the pressure of the hydraulic cylinder rises to the set pressure of the fluid closing means. There is an unsolved problem that the vehicle height changes, which causes the occupants to feel uncomfortable.

In view of the above, the present invention has been made in view of the unsolved problem of the conventional example, and provides an active suspension capable of preventing a vehicle height variation due to a loaded weight when a fluid pressure supply device stops. It is intended to be.

[Means for solving the problem]

In order to achieve the above object, an active suspension according to the present invention includes a fluid pressure cylinder interposed between each wheel and a vehicle body, and a working fluid supplied from the fluid pressure supply device to the fluid pressure cylinder. A control valve that controls the pressure, a posture change suppression control unit that individually controls the control valve based on a detection value of the posture change detection unit, and a control valve interposed between the control valve and the fluid pressure supply device. An active suspension including a pressure holding unit that closes the control valve when the supply pressure becomes equal to or lower than a predetermined pressure, wherein the pressure holding unit includes:
A pilot having a check valve inserted in a supply-side pipe connecting the fluid pressure supply device and the control valve, and a variable receipt pressure mechanism inserted in a return-side pipe connecting the fluid pressure supply device and the control valve; When the operation type check valve and the ignition switch are turned off and the average vehicle height exceeds the reference vehicle height after setting the receipt pressure according to the average command value of the attitude change suppression control means when the ignition switch is turned off. And a receipt pressure adjusting means for adjusting the receipt pressure so as to maintain the reference vehicle height.

[Action]

In the present invention, when the supply pressure of the fluid pressure supply device is equal to or higher than the predetermined pressure, the pressure holding unit is in a non-operating state,
The supply pressure of the fluid pressure supply device is directly supplied to the control valve. When the supply pressure of the fluid pressure supply device falls below a predetermined pressure due to an engine stop or the like by turning off the ignition switch from this state, the pressure holding unit is activated and includes the pressure control valve and the fluid pressure cylinder. The fluid pressure control system is closed. At this time, a variable receipt pressure mechanism is provided in the pilot operated check valve inserted in the return pipe of the pressure holding unit, and the receipt pressure variable mechanism is temporarily controlled by the receipt pressure adjusting means. After the receipt pressure is set according to the average command value, the receipt pressure is adjusted to maintain the reference vehicle height when the vehicle height average value exceeds the reference vehicle height, so that the ignition switch is turned off. Immediately after that, the holding pressure in the pressure holding unit and the pressure of the fluid pressure cylinder are made substantially equal to prevent vehicle height fluctuation, and thereafter, when the vehicle height average value is higher than the reference vehicle height, it is reduced to the reference vehicle height. Thus, smooth vehicle height control can be performed to prevent the passenger from feeling uncomfortable.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention.

In the figure, FS is a fluid pressure supply device, which is connected to the output shaft 2a of the engine 2 as a rotation drive source and is rotationally driven;
A hydraulic pump 1 having a suction side connected to an oil tank 3,
Supply side piping 5 connected to the discharge side via a check valve 4
And a return pipe 7 connected to the oil tank 3 via an oil cooler 6. An accumulator 8 for absorbing pulsation is connected to the supply pipe 5, and a filter 9 is provided downstream of the accumulator 8. Is inserted. In the filter 9, a bypass passage when the filter 7 is clogged is formed in parallel with the filter 9.
Is inserted.

The other ends of the supply-side pipe 5 and the return-side pipe 7 are connected to the input ports and return ports of the pressure control valves 13FL to 13RR corresponding to each wheel via the pressure holding unit 11 and the fail-safe valve 12 as an on-off valve. Have been.

The pressure holding unit 11 includes a check valve 14 inserted in the supply pipe 5.
And a normal line pressure setting relief valve 15 for setting a normal line pressure P _L (kg / cm ² ) interposed between the supply side pipe 5 and the return side pipe 7, and a downstream of the fail safe valve 12. Side, that is, the line pressure on the pressure control valves 13FL to 13RR side is the pilot pressure P _P
Operated pilot operated check valve 16 and check valve
A parallel circuit of an electromagnetic on-off valve 17 and a throttle 18 inserted in series immediately before 14 is provided.

Here, as shown in FIG. 2, the pilot operated check valve 16 is provided with a poppet 16b and a spool opposed to the poppet 16b in a cylindrical valve housing 16a having an input port 16i, an output port 16o and a pilot port 16p. 16c are slidably disposed together, and the poppet 16b is connected to the input port 16i and the output port.
16c is urged by a coil spring 16e in a direction to come into contact with a valve seat 16d formed between the coil spring 16e and the coil spring 16e.
Is supported by a receipt pressure variable mechanism 16f, and a pilot port is provided on a side of the spool 16c opposite to the poppet 16b.
It has a configuration in which the pilot pressure P _P is supplied from 16p.

Here, the receipt pressure variable mechanism 16f has a screw shaft 16g
A spring seat 16j is fixed to an end of the valve housing 16a and slidably disposed on a cap 16n for closing the left end of the valve housing 16a, and a screw shaft 16g is screwed to the other end. is composed of a sliding shaft 16l which is fixed a nut 16k to, by driving rotation by the controller 30 to be described later DC motor 16h, varying the receipt pressure of the poppet 16b by changing the pre-set pressure F ₀ of the coil spring 16e can do. Reference numeral 16m is a stroke sensor configured to detect the moving position of the sliding shaft 16l, for example, a potentiometer.

This pilot-operated check valve 16 has a preset coil spring 16e when the receipt pressure of the poppet 16b is P _R , the effective area of the spool 16c is A, the spring constant of the coil spring 16e is k, and the displacement of the poppet is x. Pressure F ₀ is
It can be expressed by the following equation (1).

F ₀ = P _R · A (1) When the relationship between the pilot pressure P _P and the input pressure P _i is P _i ≧ P _R , the spool 16c is separated from the poppet 16b, and the force is applied to the poppet 16b. Not transmitted, poppet 16b acts only as a relief valve function. That is, the balance in terms of _{P i · A = P R ·} A relative pressure P _i of the input port 16i, P _i> P _R
For it is open in relief state, in the case of P _i ≦ P _R in the closed state.

On the other hand, if P _i <P _P , it acts on the spool 16c (P
_P- P _i ) A force pushes poppet 16b, as if poppet
16b and spool 16c move together. Accordingly, generated by the input pressure P _i, the poppet 16b and the spool 1
The force acting on 6c becomes an internal force and cancels,
The poppet 16b is balanced in the state of the following equation (2).

F ₀ + k · x = P _P · A (2) Then, the poppet 16b is obtained from the above equations (1) and (2).
The condition for releasing the check valve function (x> 0) is as follows:
Since (P _P -P _R ) A> 0, the check valve opens when P _P > P _R and closes when P _P <P _R.

By advancing and retracting the spring seat 16j rotated and driven by a motor forward rotation control signal CS _MP or motor reverse rotation control signal CS _MN from control device 30 to be described later DC motor 16h, any receipts pressure P _R of the poppet 16b Can be changed to

The electromagnetic on-off valve 17 is controlled to a predetermined time delay open state of several seconds from the fail-safe valve 12 by the control signal CS ₂ from the controller 30 to be described later.

The fail-safe valve 12 is a spring offset type 4
A P-port connected to a downstream side of the check valve 14 of the pressure holding unit 11, an R port connected to the input port 16i of the pilot operated check valve 16, and a port connected to an input port 21i of the control valve 13FL～13RR, and a connected to the return port 21o B port, the control signal CS ₁ is turned off supplied from the control unit 30 described later to the solenoid 12a At the normal switching position switched by the return spring 12b.
Port and the R port is blocked and A port and B port in a state that is communicated with each other, directly communicating the P port and A port offset switching position control signal CS ₁ is turned on to be supplied to the solenoid 12a A communication path and a communication path that directly communicates between the R port and the B port are formed. The R port and the B port of the fail-safe valve 12 are communicated via an external fixed throttle 12c.

Each of the pressure control valves 13FL to 13RR is connected to the input port 21.
i, a return port 21o, a control pressure port 21c, a control pressure port 21c, an input port 21i, and a return port 21c.
o is shut off or the control pressure port 21c and the input port 21i
A supply pressure and a control pressure are supplied to both ends of the spool as pilot pressure, and further controlled by a proportional solenoid 22 on the supply pressure side. It has a configuration in which a poppet valve is provided, and is controlled so that the pressure of the control pressure port 21c always becomes a pressure corresponding to the exciting current supplied from the control device 30 described later to the proportional solenoid 22.

The input ports 21i of the pressure control valves 13FL to 13RR are connected to the A port of the fail-safe valve 12, and the return port
21o is connected to the B port of the fail-safe valve 12, and the control port 21c is connected to the pressure chamber 1 of each of the hydraulic cylinders 19FL to 19RR.
Connected to 9a.

Here, the excitation current I _FL relationship ~I _RR and the control hydraulic pressure P _C output from the control port 21c, as shown in FIG. 2, P when the command value I _FL ~I _RR is close to zero outputs _MIN, the command value I _FL ~I _RR from this state is increased in the positive direction, this with a predetermined proportional gain K ₁ increases the control pressure P _C is at set line pressure P _H of the pressure holding portion 11 Saturates.

A back pressure absorbing accumulator 26F is connected to the return pipe 21F communicating between the return ports 21o of the pressure control valves 13FL and 13FR and the B port of the fail-safe valve 12,
The return side pipe 25R communicating between the return port 21o of the pressure control valves 13RL and RR and the B port of the fail-safe valve 12 includes:
The back pressure absorbing accumulator 26R is connected to absorb the back pressure generated by the line resistance of the pressure oil flowing through the return pipes 25F and 25R.

Also, cylinder tube of each hydraulic cylinder 19FL-19RR
Vehicle height sensors 28FL to 28RR configured to detect a vehicle height, for example, a potentiometer, are provided between the vehicle height sensors 19b and 19c, and the vehicle height detection values H of these vehicle height sensors 28FL to 28RR are provided.
_FL to H _RR is input to the controller 30.

As shown in FIG. 4, the control device 30 includes at least an interface circuit 31a, an arithmetic processing device 31b, and a storage device.
The stroke sensor 1 is provided on the input side of the interface circuit 31a.
With the movement position detection value P _D of 6m is input via an A / D converter 32, the vehicle height detected values H _FL from the vehicle height sensors 27FL~27RR
~ H _RR is input via the A / D converters 33FL to 33RR, and further detects the vehicle speed detection value V from the vehicle speed sensor 28 for detecting the vehicle speed, the power supply circuit, and the abnormal state of the control system such as the pressure control valves 13FL to 13RR. The abnormality detection signal AS from the abnormal state detector 29 to be detected is input, and the command values I _{FL to} I _RR output from the output side are set in a floating type using an operational amplifier via D / A converters 34 _{FL to} 34 _RR. Solenoid drive circuit 35 composed of current circuit
Control signals CS ₁ and CS ₂ supplied to FL to 35RR and output from the output side are supplied to solenoid drive circuits 36 and 37, and a motor forward drive signal CS _MP and a motor reverse drive signal CS _MN are supplied to the motor. It is supplied to the drive circuit 38.

Then, the excitation current corresponding to the command values I _{FL to} I _RR output from the solenoid drive circuits 35 _FL to 35 _RR is applied to each of the pressure control valves 13 FL.
The excitation currents supplied to the proportional solenoids 22 to 13RR and output from the solenoid drive circuits 36 and 37 are supplied to the solenoids of the fail-safe valve 12 and the solenoid on-off valve 17, respectively, and the drive current output from the motor drive circuit 38 Is supplied to the DC motor 16h of the pilot operated check valve 16.

Processor 31b, when the ignition switch is turned on, the control signal CS ₁ to the fail-safe valve 12 to the open state to an on state, then the pilot-operated check valve 16 of the pressure holding portion 11 is opened when sufficient predetermined time has elapsed becomes, while the solenoid valve 17 to the open state of the control signal CS ₂ as the oN state, the vehicle height sensor 28FL~
The vehicle height detection values H _{FL to} H _RR are read from the 28RR, and the command value I _FL is set based on these values and the target vehicle height value H _S so that they match.
~ I _RR is selected and vehicle height adjustment processing is performed, and then when the vehicle is in a running state, the receipt pressure of the pilot operated check valve 16 is
The P _R was controlled to the neutral pressure P _N which corresponds to the pressure of the hydraulic cylinder 19FL~19RR At standard load weight, when the ignition switch is turned from on state to an off state, the command value I
_FL ~I _RR calculates the average value, the average control pressure P of the average value by referring to the storage table corresponding to Figure 3 which is stored in advance in the storage device 31c based on the pressure control valve 13FL~13RR calculating the _C, then the DC motor 16h as receipts pressure P _R of the pilot-operated check valve 16 matches the average control pressure P _C and rotated in the pressure holding unit 11, the vehicle height by the subsequent occupant gets off such There upon rising, to perform the vehicle height lowering processing to match the target vehicle height is lowered a receipt pressure P _R of the pilot-operated check valve 16.

Further, the processing unit 31b, when the abnormality detection signal AS from the abnormal state detector 29 is turned on, the fail-safe valve 12 a control signal CS ₁ is running external interrupt processing is turned off closed Control the state.

The storage device 31c stores a program required for the arithmetic processing of the arithmetic processing device 31b, stores a storage table corresponding to FIG. 3, and sequentially stores data in the arithmetic process of the arithmetic processing device 31b. I do.

In addition, power from a DC power supply 39 such as a battery is supplied to the control device 30 via a power supply holding unit 40 having an off-delay timer. In this power supply holding unit 40, an ignition switch is turned off and the engine 2 is stopped. After that, the power-on state is maintained until a predetermined time elapses.
30 remains active.

41F is an accumulator for accumulating pressure connected to the hydraulic piping between the A port of the fail-safe valve 12 and the input port 21i of the pressure control valves 13FL and 13FR, and 41R is a fail-safe valve 1
2 A port and input port 21i of pressure control valve 13RL, 13RR
An accumulator for animal pressure connected to the hydraulic line between, 42
And 43 are damping valves and accumulators for absorbing pressure fluctuations in the high frequency range of the vehicle unsprung vibration from the road surface input to the hydraulic cylinders 19FL to 19RR, and 44F and 44R are used when an abnormally high pressure is generated in the return pipe 7. Supply abnormally high pressure to piping 5
The check valve 45 is a throttle for keeping the back pressure of the return pipes 25F, 25R at several kgf / cm ² to prevent separation of the oil column in the return pipes 25F, 25R.

Next, the operation of the above embodiment will be described. Now, it is assumed that the vehicle is in a stopped state and the ignition switch is in an off state. In this state, the engine 2 is in the rotation stopped state, the hydraulic pump 1 is also in the stopped state, and the pressure holding unit 11
Since the pilot operated check valve 16 is fully closed, the pressure control valves 13FL to 13RR side have a closed circuit, and the fluid pressure supply device FS has been deactivated after the previous traveling stop. The fluid pressure at this time or the fluid pressure which has been reduced due to leakage of hydraulic oil or a decrease in the volume of hydraulic oil is sealed.

In this state, by turning on the ignition switch, the power is turned on to each of the vehicle height sensors 28FL to 28RR, the abnormal state detector 29, and the control device 30. Therefore,
The posture change suppression processing shown in FIG. 6 is executed by the microcomputer 31 of the control device 30.

That is, initialization is performed in steps, and the control signal CS
₁ is turned on, the control signal CS ₂ is turned off, and command values I _{FL to} I _RR for the pressure control valves 13FL to 13RR are set.
Set to I _MIN .

Next, the process proceeds to a step, wherein the receipt pressure variable mechanism is set.
The stroke detection value L _D of the 16 m stroke sensor 16 m is read, and then the process proceeds to the step where the stroke detection value L _D
Calculating the receipt pressure P _R by referring to the storage table showing the relationship between the stored stroke detected value L _D and the receipt pressure P _R to the previously stored device 31c based on.

Then, the processing proceeds to step, the receipt pressure receipts pressure P _R by referring to the storage table corresponding to FIG. 3 based on
Calculating a command value I _FL ~I _RR of the pressure control valve 13FL~13RR corresponding to P _R, then the command value I which is calculated by proceeds to step
The _FL ~I _RR is output to the solenoid drive circuit 35FL~35RR,
Controlling the control pressure P _C of the pressure control valve 13FL～13RR.

Next, the process proceeds to a step where the discharge pressure of the hydraulic pump 1 of the supply device FS is set to the line pressure P _L set by the relief valve 12.
Determine whether a predetermined time sufficient to reach
When the predetermined time has not elapsed, which waits until the elapsed when a predetermined time has elapsed, the process proceeds to step the solenoid valve 17 to the open state of the control signal CS ₂ as the ON state, then to step The process proceeds to activate the vehicle height adjustment process shown in FIG. 7, and then proceeds to the step.

In this step, a vehicle speed detection value V of the vehicle speed sensor 28 is read, and it is determined whether or not the vehicle is in a traveling state. When the vehicle is in a stopped state, the vehicle stands by until the vehicle enters a traveling state,
Proceeds to step when a running state is set by controlling the DC motor 16h receipt pressure varying mechanism 16f receipts pressure P _R of the pilot-operated check valve 16 to be equal to the neutral pressure P _N .

Next, the process proceeds to a step, where it is determined whether or not the ignition switch has been switched from the ON state to the OFF state. When the ignition switch is in the ON state, the process waits until the ignition switch is turned OFF, and the ignition switch is switched from the ON state to the OFF state. to when switched, the process proceeds to step calculates an average value I _M command value I _FL ~I _RR at that time, then in FIG. 3 based on the average instruction value I _M and proceeds to step refer to the corresponding storage table calculates the average control pressure P _CM, then the receipt pressure P _R of the pilot-operated check valve 16 with reference to the predetermined storage table moves and the average control pressure P _C in step equal receipt-pressure calculating a target stroke L _T of varying mechanism 16f, and then proceeds to step motor forward control signal to the target stroke L _T and the stroke detection value L _D matches The CS _MP or CS _MN outputs to the DC motor 16h receipt variable mechanism 16f.

Next, the process proceeds to a step, in which the vehicle height lowering process shown in FIG. 7 is started, and then the process is terminated.

Here, the vehicle height adjustment process is executed as a timer interrupt process at predetermined time intervals (for example, 20 msec) as shown in FIG.
H _FL to H _RR reads, then difference value between the target vehicle height H _S of preset and migrated is loaded in each car height detecting value H _{i (i} = FL~RR) to step (H _S -H _i ) Is calculated, and then the process proceeds to step to determine whether or not the absolute value | H _S -H _i | of the difference value exceeds a predetermined set value ΔH which is a preset dead zone for preventing hunting. This determination is for determining whether or not to perform vehicle height adjustment. When | H _S −H _i | ≦ ΔH, it is determined that the vehicle height is normal, and the timer interrupt processing is terminated as it is. , | H _S −H _i |> ΔH, it is determined that the vehicle height is out of the appropriate value, and the process proceeds to step.

In this step, it is determined whether the difference value calculated in step (H _S -H _i) is positive. This judgment is
It is determined whether or not the vehicle height is lower than the target vehicle height. When H _S −H _i > 0, it is determined that the vehicle height is low, and the process proceeds to the step, and the previous command value is determined. The value obtained by adding the predetermined value ΔI to I _i-1 is used as the current command value I _i in the storage device 31c.
After the data is updated and stored in the command value storage area formed in the step (a), the process proceeds to the step. If H _S −H _i <0, it is determined that the vehicle height is high, and the process proceeds to the step to execute the previous command value I _{i -1}
The process proceeds to step a value obtained by subtracting a predetermined value ΔI from the updated and stored in the command value storage area as a current command value I _i from.

In the step, the command values I _{FL to} I _RR stored in the specified value storage area are output to the D / A converters 34 _FL to 34 _RR, and then the timer interrupt processing is ended and the program returns to the main program.

Here, the predetermined value ΔI in the step or the processing of the step is selected to be a relatively small value so as to prevent a sudden change in the vehicle height and perform gentle vehicle height adjustment. This vehicle height adjustment processing is repeatedly executed until the power supply from the power supply holding unit 40 is cut off.

Also, as shown in FIG. 7, the vehicle height lowering process is executed as a timer interrupt process at predetermined time intervals (for example, 20 msec), and the vehicle height detection values H _{FL to} H _RR are read in steps, and then read in steps. calculates an average value H _M of the vehicle height detected values H _FL to H _RR I, then the process proceeds to step determines whether the vehicle height average value H _M rises above the reference vehicle height H _S, H _{When M−} H _S ≦ 0, it is determined that there is no increase in the vehicle height, and the process proceeds to the step where the motor reverse rotation control signal CS _MN is turned off to end the timer interrupt processing, and H _M −H _S > 0 In some cases, it is determined that the vehicle height has risen due to the occupant getting off the vehicle, unloading the load, and the like.
After outputting the CS _MN to the motor drive circuit 38, the timer interrupt processing ends. Then, this vehicle height lowering processing is performed by the power
It is repeatedly executed until the power supply from is stopped.

Here, the processing of steps 1 to 5 of FIG. 5 and the vehicle height lowering processing of FIG. 7 correspond to the receipt pressure adjusting means.

Therefore, when the ignition switch is turned on, the engine 2 starts and enters the idling state,
As the rotation speed of the output shaft 2a increases, the rotation speed of the hydraulic pump 1 also increases, and the operating oil of the discharge pressure corresponding to the rotation speed flows through the supply pipe 5 to the check valve 14 of the pressure holding unit 11. Supplied to

At this time, the control device 30, when the ignition switch is turned on, the first control signal CS ₁ as well as the fail-safe valve 12 is turned on to an open state, the stroke of the stroke sensor 16m in the receipt pressure varying mechanism 16f It reads the detection value L _D, and calculates the current receipt pressure P _R on the basis of the stroke detected value L _D, the receipt pressure
By calculating the command value I _FL ~I _RR of the pressure control valve 13FL~13RR the P _R to the original, controls the proportional solenoid 22 of the pressure control valve 13FL~13RR Based on these, the pressure control valve 13FL~13
The control pressure P _C of the RR is controlled to be substantially equal to the holding pressure of the receipt pressure P _R or pressure holding unit 11.

For this reason, until the predetermined time has elapsed, the control signal CS ₁
Only the fail-safe valve 12 is controlled to be in the open state, and the solenoid on-off valve 17 is maintained in the closed state, so that the fluid pressure supply device FS and the check valve 14 of the pressure holding unit 11 are closed. The supply side pipe 5 is in communication with only the throttle 18,
The pressure increase on the input side of the check valve 14 is performed slowly. Therefore, when the pressure of the supply side pipe 5 becomes equal to or higher than the holding pressure actually held by the pressure holding unit 11, the pressure of the closed circuit gradually increases, and the pressure chambers of the hydraulic cylinders 19FL to 19RR are correspondingly increased.
Since the pressure of 19a is gradually increased, the vehicle height is gradually increased.

When the pressure in the A port side of the fail-safe valve 12 in the supply pipe 5 is equal to or greater than the receipt pressure P _R of the pilot-operated check valve 16 in the pressure holding unit 11, a pilot-operated check valve 16 and the open position As a result, the pressure holding state is released. At this time, the control pressure P of the pressure control valves 13FL to 13RR
_C is because it is equal and control the receipt pressure P _R, the pressure in the pressure chamber 19a of the hydraulic cylinder 19FL~19RR is maintained at a constant value, it does not involve the vehicle height variation.

Thereafter, when a predetermined time elapses, the controller is output from the 30 control signals CS ₂ is turned on, the pressure oil is the pressure hold from a fluid pressure supply device FS is solenoid valve 17 is an open state in accordance with this is supplied to the pressure control valve 13FL~13RR through the section 11, then the vehicle height adjustment processing is started vehicle height based on the vehicle height detection value H _FL to H _RR of the vehicle height sensor 28FL~28RR by controller 30 The appropriate vehicle height (target vehicle height) is maintained. When the vehicle height adjustment processing is started, when a significantly different relative to the vehicle height detected values H _FL to H _RR reference vehicle height H _S is the vehicle height of the raised or lowered is performed, the vehicle height at this time The change does not cause the occupant to feel uncomfortable because the vehicle height adjustment is performed gently because the increment ΔI of the command value is selected to be small in the above-described step or the process of FIG.

Thereafter, when the vehicle and the traveling state, the neutral pressure P _N which corresponds to the pressure required to maintain the target vehicle height in the standard loading state receipts pressure P _R of the pilot-operated check valve 16 from the controller 30
And the vehicle height adjustment processing for maintaining the vehicle height at the target vehicle height is continued, and the command values I _{FL to} I _FL
By outputting _RR to the pressure control valves 13FL to 13RR, the pressure of the hydraulic cylinders 31FL to 31RR is controlled, and a change in the vehicle height of the vehicle body is suppressed. Thus, when the vehicle is traveling state, by the receipt pressure P _R of the pilot-operated check valve 16 is set to a value equal to the neutral pressure P _N, the roll suppression control during traveling of the vehicle, the pitch reduction control When the posture change suppression control such as is performed, it is possible to prevent the pressure holding unit 11 from becoming unnecessarily in the pressure holding state when the consumption of hydraulic oil increases and the supply pressure of the fluid pressure supply device FS decreases. can do.

Thereafter, when the vehicle is stopped, the vehicle height adjustment pressure is controlled to maintain the target vehicle height according to the change in the weight of the occupant and the load at that time.

When the ignition switch is turned off in this stopped state, power supply from the power supply 38 to the control device 30 is continued for a predetermined time by the power supply holding unit 39, and the vehicle height adjustment processing by the microcomputer 31 is continued. On the other hand, when the ignition switch is turned off, the control device 30
In calculates an average value I _M command value I _FL ~I _RR for each pressure control valve 13FL～13RR, average control pressure by referring to the storage table corresponding to FIG. 3 and the average value I _M based on to calculate the P _CM,
The receipt pressure P _R corresponding to the average control pressure P _CM is calculated, the receipt pressure P _R of the pilot-operated check valve 16 is controlled to a value equal to the average control pressure P _CM. That is, when the vehicle loading weight is the standard loading weight, the pressure control valves 13FL to 13FL
Since the control pressure P _C of the 13RR is in the neutral pressure P _N, also the receipt pressure P _R of the pilot-operated check valve 16 is controlled to the neutral pressure P _N, heavier than the standard load weight (or light) Sometimes, control since pressure P _C is a value greater than the neutral pressure P _N (or a small value), is controlled on the receipt pressure P _R is likewise greater than the neutral pressure P _N (or a small value).

On the other hand, the engine 2 is stopped by the off state of the ignition switch, thereby stopping the hydraulic pump 1 of the fluid pressure supply device FS, and the discharge pressure is rapidly reduced.
Since the check valves 4 and 11 are interposed in the supply pipe 5, the pressure control valves 13FL to 13RR and the accumulators 40F and 40R are provided.
Although the pressure of the return pipe 25 does not suddenly decrease, the hydraulic oil of the supply pipe 5 returns to the return pipe 25 through the pressure control valves 13FL to 13RR.
Since the pressure is gradually returned to the oil tank 3 via F, 25R and 7, the pressure on the downstream side of the check valve 14 of the supply pipe 5, that is, the temporary supply pressure of the pressure control valves 13FL to 13RR gradually decreases, When this falls below the set pressure P _N of the pilot operated check valve 16,
The pilot operated check valve 16 is fully closed, and the pressure control valves 13FL to 13RR are closed. Thus, when the pilot-operated check valve 16 is fully closed, the return-side pipe 25F between the pilot-operated check valve 16 and the pressure control valve 13FL～13RR, the pressure P _R of 25R rise It was started, the back-pressure suction acquisition accumulators 26F, since also rises accumulator of 26R, supply pressure P _S of the primary side of the pressure control valve 13FL~13RR is decreased, pressure P _R and return the supply pressure P _S Is equal to, the pressure in the closed circuit becomes a constant value, which is maintained. At this time, since the receipt pressure P _R of the pilot-operated check valve 16 is controlled to an average control pressure P _CM of the pressure control valve 13FL~13RR when an ignition switch is turned off, the pressure in the closed circuit deadweight Pressure will be maintained according to the return side piping
A pressure drop required to fill the 25F, 25R and the back pressure absorbing accumulators 26F, 26R occurs, but the pressure drop is small, the vehicle height fluctuation is small, and the passenger does not feel uncomfortable.

Incidentally, in the case where the receipt pressure P _R of the pilot-operated check valve 16 is fixed at the neutral pressure P _N required to maintain the standard vehicle height, the load weight when the ignition switch turned off when heavier than the standard load weight is decreased from the neutral pressure P _N higher control pressure P _C to the neutral pressure P _N, the backtracking side pipe 25F, 25R and the back-pressure suction expropriation accumulator 26
F, will be a pressure drop which is used to fill 26R occur, will be the vehicle height is large down, when load weight on the contrary lighter than the standard load weight from the neutral pressure P lower than _N control pressure P _C increased pressure to the neutral pressure P _N, the backtracking side pipe 25
The pressure used to fill the F, 25R and the back pressure absorbing accumulators 26F, 26R is reduced, so that the vehicle height once rises and then falls, giving the occupant an uncomfortable feeling.

Incidentally, even if the ignition switch is turned off, by the vehicle height adjustment processing is continued for a predetermined time, the control unit 30, the control pressure P _C of the pressure control valve 13FL~13RR is necessary to maintain the target vehicle height The pressure is controlled, and in this state, the vehicle height lowering process is started by the control device 30.When the occupant gets off or unloads the load, when the vehicle body weight is reduced and the vehicle height is increased, the vehicle height is increased. the high descent process, a receipt-pressure by varying mechanism 16f is controlled, will be the receipt pressure P _R of the pilot-operated check valve 16 is lowered, the hydraulic cylinder 19FL reduced pressure the resulting closed circuit
The pressure of ~ 19RR also decreases, and accordingly, the vehicle height decreases and the target vehicle height can be maintained.

Thereafter, when the occupant gets on the vehicle and turns on the ignition switch to start the engine 2, the sudden change in vehicle height is prevented as described above, and the occupant does not feel uncomfortable.

Also, when the fluid pressure supply device FS fails for some reason during running of the vehicle and the discharge pressure of the hydraulic pump 1 becomes zero, the primary supply pressures of the pressure control valves 13FL to 13RR decrease. As a result, the pilot-operated check valve
16 is switched to the fully closed state, and the pressure is maintained.
Steering stability is not impaired by sudden changes in vehicle height.

Further, when the proportional solenoid 22 of the pressure control valves 13FL to 13RR is short-circuited or disconnected in a state where the ignition switch is turned on and the pressure control valves 13FL to 13RR do not operate normally, this is detected as an abnormal state. detected in vessels 29, since the abnormality detection signal aS is turned on, the control signal CS ₁ is turned off to be output from the controlling device 30,
The failsafe valve 12 is switched to the closed state. Therefore, the input port 21i and the return port 21o of the pressure control valves 13FL to 13RR are in communication with each other, and the pilot-operated check valve 16
Will be the pilot pressure P _P in is reduced, the pilot-operated check valve 16 becomes fully closed, a pressure holding state.

Also, if an abnormality occurs in the power supply system including the DC power supply 39,
When the power supplied to the control device 30 is cut off, the command values I _{FL to} I _RR and the control signal CS ₁ output from the control device 30 are turned off, and the fail-safe valve 12 is closed as described above. As a result, the pressure holding unit 11 enters a pressure holding state. In this case, the receipt pressure varying mechanism 16f is not possible receipt pressure P _R is changed since a motor-driven, never body posture becomes unstable.

In the above embodiment, the receipt pressure variable mechanism 16
As f, the case where the linear drive mechanism using the screw shaft 16g driven by the motor has been described, but the invention is not limited to this, and the spring is formed by the eccentric cam driven by the motor and the cam follower engaged with the cam. Sheet 16j
May be performed, and any other linear movement mechanism may be applied.

Further, in the above embodiment, the command value based on the receipt pressure P _R when the ignition switch to the ON state
Has been described for the case where the immediately after the timing of outputting the I _FL ~I _RR and the on-state ignition switch, is not limited to this, any prior pilot-operated check valve 16 is fully opened For example, the command values I _{FL to} I _RR can be output at any timing.

Further, in the above-described embodiment, the case where the parallel circuit of the electromagnetic on-off valve 17 and the throttle 18 is inserted in the pressure holding unit 11 has been described, but the present invention is not limited to this. The safe valve 12 may be controlled to be opened at the same timing as the electromagnetic on-off valve 18.

Still further, in the above embodiment, the liquid pressure supply device
A case has been described where it is determined whether or not the FS is in the operating state based on whether or not the ignition switch is in the on state. However, the present invention is not limited to this, and the rotational speed of the rotating shaft of the engine 2 is directly detected. Alternatively, the discharge pressure of the hydraulic pump 1 may be detected.

Furthermore, in the above embodiment, the case where the control device 30 is configured to include the microcomputer 31 has been described. However, the configuration is not limited to this, and the control device 30 may be configured by combining electronic circuits such as a comparison circuit, a timer, and a logic circuit. Is also good.

Further, in the above embodiment, the case where the rotational driving force of the hydraulic pump 1 is obtained from the engine 2 has been described. However, the present invention is not limited to this, and a rotational driving source such as an electric motor may be applied. It goes without saying that you get it.

Further, as the control valve, the pressure control valves 13FL to 13RR
However, the present invention is not limited to this, and other flow control type servo valves and the like can be applied.

Further, in the above-described embodiment, the case where the working oil is used as the working fluid has been described. However, the present invention is not limited to this, and any working fluid may be used as long as the fluid has a low compression ratio.

〔The invention's effect〕

As described above, according to the active suspension of the present invention, the pressure of the fluid pressure control system including the control valve and the fluid pressure cylinder is maintained when the fluid pressure supply device is changed from the operating state to the inactive state. A pressure-operating check valve having a check valve inserted in the supply pipe and a receipt pressure variable mechanism inserted in the return pipe, and an ignition switch that is turned off when the ignition switch is turned off. After setting the receipt pressure according to the average command value of the attitude change suppression control means, the receipt pressure adjusting means for adjusting the receipt pressure so as to maintain the reference vehicle height when the vehicle height average value exceeds the reference vehicle height, When the ignition switch is turned off, after setting the receipt pressure according to the average command value of the attitude change suppression control means, the vehicle height average value exceeds the reference vehicle height. The receipt pressure adjustment means for adjusting the receipt pressure so as to maintain the reference vehicle height, so that when the ignition switch is turned off and the fluid pressure supply device becomes inactive, the pilot operation type reverse The receipt pressure of the stop valve is set to a value corresponding to the average value of the control pressure of the control valve at that time, and the fluid pressure control system can be maintained at a pressure corresponding to the load weight. By reducing the amount, and then adjusting the receipt pressure to maintain the reference vehicle height when the average vehicle height exceeds the reference vehicle height, the vehicle height is smoothly adjusted and The effect of surely preventing the discomfort from being given is obtained.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention, FIG. 2 is a sectional view showing an example of a pilot-operated check valve applicable to the present invention, and FIG. 3 is control for a command value of a pressure control valve. FIG. 4 is a characteristic diagram showing a pressure relationship, FIG. 4 is a block diagram showing an example of a control device, and FIGS. 5 to 7 are flowcharts showing an example of a processing procedure in the control device. In the figure, FS is a fluid pressure supply device, 1 is a hydraulic pump, 2 is an engine, 5 is a supply side pipe, 7 is a return side pipe, 11 is a pressure holding unit, 12 is a fail-safe valve, and 13FL to 13RR are pressure control valves. ,
14 is a check valve, 16 is a pilot operated check valve, 16a is a valve housing, 16b is a poppet, 16e is a coil spring, 16
f is a variable receipt pressure mechanism, 16g is a screw shaft, 16h is a DC motor, 16j is a spring seat, 19FL-19RR is a hydraulic cylinder (fluid pressure cylinder), 27FL-27RR is a vehicle height sensor, 29 is an abnormal state detector, 30 Is a control device, and 31 is a microcomputer.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Yamanaka 2548 Dota, Kani-shi, Gifu Prefecture Kayaba Industrial Co., Ltd.Gifu-Kita Plant, Inc. (56) References JP-A-3-90425 (JP, A) JP-A-63-219408 (JP, A) JP-A-63-152723 (JP, U) JP-A-64-56304 (JP, U) Japanese Utility Model Hei 1-59716 (JP, U) Japanese Utility Model Hei 1-109417 (JP, U) Japanese Utility Model Hei 1-95411 (JP, U) (58) Fields surveyed (Int.Cl. ⁶ , DB name) B60G 17/015

Claims (1)

(57) [Claims] 1. A hydraulic cylinder interposed between each wheel and a vehicle body, a control valve for controlling a working fluid pressure from a hydraulic pressure supply device supplied to the hydraulic cylinder, and the control valve. An attitude change suppression control means for individually controlling based on a detected value of the attitude change detection means, and a control means interposed between the control valve and the fluid pressure supply device for controlling when a supply pressure of the control valve becomes a predetermined force or less. In an active suspension including a pressure holding unit having a valve-side closed circuit, the pressure holding unit includes a check valve inserted in a supply-side pipe connecting the fluid pressure supply device and the control valve, A pilot-operated check valve having a receipt pressure variable mechanism inserted in a return pipe connecting the pressure supply device and the control valve, and when the ignition switch is turned off, the attitude change suppression control means Review according to the average command value. And a receipt pressure adjusting means for adjusting the receipt pressure so as to maintain the reference vehicle height when the vehicle height average value exceeds the reference vehicle height after the vehicle pressure is set to the reference pressure. .