JPH0822651B2 - Pressure control valve and active suspension using the control valve - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic pressure control valve for controlling the working pressure of a fluid pressure cylinder and an active suspension for a vehicle using the control valve. The present invention relates to a structure having a fail-safe function capable of appropriately coping with an abnormality (fail) caused by a disconnection of an electric system for giving a command value to a pressure control valve, a power down, or the like.

[Prior Art] As an active suspension of this type, there is, for example, the one described in Japanese Patent Application No. 62-301726 previously filed by the present applicant.

As one mode of this active suspension, a hydraulic cylinder arranged on each wheel, a hydraulic source for supplying an operating pressure to this hydraulic cylinder, and a pressure for controlling the operating pressure according to a command value from a posture change control device A check valve equipped with a control valve, and a check valve installed in the supply path to the pressure control valve, and a return path installed when the supply pressure to each control valve of the hydraulic pressure source installed in the return path is below a predetermined value. A pilot operated check valve that closes, a switching valve that is on the downstream side of the check valve and that has a mode that shuts off the supply path in the event of an abnormality and connects the load side of the blocked supply path to the return path, and this switching valve. A control mechanism for controlling the operation is provided. This control mechanism monitors whether or not the above-mentioned abnormality has occurred in the command value given to each pressure control valve, and when the abnormality occurs, the switching valve is set to the abnormal mode.

Here, the pressure control valve is disclosed in, for example, JP-A-63-219408.
It has the structure described in No.

Therefore, in a normal operating state in which no abnormality (hereinafter referred to as “fail”) due to a disconnection of the electric system for giving a command value to the pressure control valve, power down, etc. does not occur, the switching valve individually supplies the supply path and the return path. Since the pilot-operated check valve is open for communication, the discharge pressure of the hydraulic source is supplied to the load side. On the other hand, if a failure occurs, the switching valve and the pilot operated check valve are activated, and the load side flow path of these valves is confined to the set pressure, so the vehicle body has a posture that allows traveling based on the enclosed pressure. it can.

[Problems to be Solved by the Invention]

However, in the active suspension having the pressure control valve, when a failure occurs, a cylinder pressure sudden change occurs immediately after that by the following process. Explaining this state with the structure of the pressure control valve described in JP-A-63-219408, the thrust of the proportional solenoid disappears stepwise due to the occurrence of a failure, so that the hydraulic balance at both ends of the spool is disrupted and the spool is proportional. The output port and the return port communicate with each other by moving to the solenoid side, the hydraulic fluid of the hydraulic cylinder returns to the hydraulic pressure supply device side within a short time, and the cylinder pressure drops sharply. As a result, the stroke between the wheel and the vehicle body related to the occurrence of a failure suddenly becomes smaller,
There was an unsolved problem that a sudden change in the body posture occurred. Further, in the active suspension having the configuration described in the prior application, even if the operating pressure is confined by the switching valve and the pilot operated check valve when a failure occurs, the hydraulic oil in the cylinder escapes before the sealing. As a result, the enclosed pressure becomes equal to or lower than the target enclosed pressure, and there is an unsolved problem that it is difficult to secure an appropriate vehicle body posture and vehicle height value at the time of failure.

The present invention has been made in view of the above-mentioned unsolved problems, and in particular, when a failure occurs, a sudden change in the stroke variation of the fluid pressure cylinder of the controlled device and a sudden change in the vehicle body posture of the active suspension are achieved with a simple structure. Making sure that things can be eliminated is the challenge to be solved.

[Means for solving the problem]

In order to solve the above problems, a pressure control valve according to claim (1) includes a valve housing having a supply port connected to a fluid pressure supply device, a return port, and an output port connected to a fluid pressure cylinder, A spool disposed in the insertion hole in the valve housing in a zero-wrapped state or an overlapped state, and a pilot channel for communicating between the supply port and the return port in a communicating state with a pilot chamber provided on one end side of the spool, A pilot valve, which is urged by the thrust of a proportional solenoid driven based on a command value, moves in the pilot passage to adjust the pressure in the pilot chamber, and is connected to the output port provided on the other end side of the spool. A feedback chamber; and a bypass flow passage that allows the feedback chamber and the pilot flow passage to communicate by bypassing the insertion hole. If the command value is a normal value, the pilot valve closes the opening portion value of the passage to the pilot flow path, and if the command value is an abnormal value, the pilot The valve is set at a position where the opening is exposed.

Further, in the active suspension according to claim (2),
A fluid pressure cylinder interposed between the vehicle body and the wheels, and a pressure control valve that controls the supply pressure supplied to the fluid pressure cylinder from the fluid pressure supply device according to a command value that corrects the posture change of the vehicle body. In the equipped active suspension,
The pressure control valve includes a valve housing having a supply port connected to the fluid pressure supply device, a return port, and an output port connected to the fluid pressure cylinder, and a zero lap or an overlap in an insertion hole in the valve housing. A spool arranged in a lap state, a pilot channel for communicating between the supply port and the return port in communication with a pilot chamber provided at one end of the spool, and a thrust force of a proportional solenoid driven based on a command value. A pilot valve that is urged to move in the pilot channel to adjust the pressure in the pilot chamber, a feedback chamber that is provided at the other end of the spool and communicates with the output port, and the feedback chamber and the pilot channel And a bypass flow path for communicating the bypass path by bypassing the insertion hole, and opening the bypass flow path to the pilot flow path. The position where the pilot valve blocks the opening when the command value is a normal value, and the pilot valve exposes the opening when the command value is an abnormal value. The structure is set to.

Further, in the active suspension according to claim (3), the fluid pressure cylinder interposed between the vehicle body and the wheels and the supply pressure supplied from the fluid pressure supply device to the fluid pressure cylinder are used to change the posture of the vehicle body. In an active suspension including a pressure control valve that controls according to a command value to be corrected, the pressure control valve is connected to a supply port connected to the fluid pressure supply device, a return port, and the fluid pressure cylinder. Valve housing having an output port, a spool disposed in the insertion hole in the valve housing in a zero-wrapped state or an overlapped state, and the supply port and the return port in communication with a pilot chamber provided at one end of the spool. It moves in the pilot flow passage by being urged by the thrust of the pilot flow passage that connects the ports and the proportional solenoid that is driven based on the command value. A pilot valve that adjusts the pressure in the pilot chamber, a feedback chamber that is provided at the other end of the spool and communicates with the output port, and a bypass that allows the feedback chamber and the pilot flow passage to communicate by bypassing the insertion hole. A flow path, the opening position of the bypass flow path to the pilot flow path, when the command value is a normal value, the pilot valve closes the opening, and the command value is In the case of an abnormal value, the pilot valve is set to a position where the opening is exposed, and an abnormal condition judging means for judging an abnormal condition of the command value, and this abnormal condition judging means detects an abnormal condition of the command value. When the judgment is made, the fluid pressure supply passage to the pressure control valve is shut off, and the flow passage switching valve connecting the load side of the shut off supply passage to the return passage and the supply pressure to the pressure control valve are lowered. When the value below and a closing valve for interrupting the return path.

[Action]

First, in the pressure control valve according to the first aspect, it is assumed that the command value given to the proportional solenoid suddenly drops to zero due to a wire breakage of the harness or a power down. Due to this failure, the thrust of the proportional solenoid with respect to the pilot valve disappears, the pilot valve retracts, and the pressure in the pilot chamber (pilot pressure) tends to drop sharply. On the other hand, due to the backward movement of the pilot valve, the pilot channel and the feedback chamber communicate with each other via the bypass channel, and the pilot chamber and the pilot channel communicate with each other, so that at least the pressure in the feedback chamber (feedback pressure) It is the same as the pilot pressure.

In other words, when a failure occurs, the pressure on both ends of the spool is temporarily held at the same pressure, and the spool is centered. As a result, the pressure (control pressure) at the output port can be blocked or enclosed by the spool, and the pressure value can be temporarily held. After that, the control pressure, that is, the pressure of the fluid pressure cylinder, is fed back to the feedback chamber, the bypass flow passage, the pilot flow passage,
And gradually return to the fluid pressure supply via the return port.
Therefore, it is possible to surely prevent the stroke of the fluid pressure cylinder from abruptly changing when a failure occurs.

In the active suspension according to claim (2), the action of the pressure control valve is the same as that according to claim (1). Therefore, a sudden change of the vehicle body when a fail occurs can be reliably prevented.

Further, in the active suspension according to claim (3), the action of the pressure control valve is the same as that of claim (1). Further, after the control pressure is temporarily held, the abnormal state determination means determines the abnormality of the command value in parallel with the state where the control pressure is gradually reduced, so that the flow path switching valve causes the supply path to the pressure control valve. Shut off and connect the load side of the supply path to the return path. As a result, the working fluid on the supply port side of the pressure control valve immediately returns to the tank of the fluid pressure supply device, and the supply pressure drops.When the supply pressure drops to a predetermined value, the on-off valve closes the return path. The load side is filled with supply pressure = control pressure = return pressure. That is, since the operating pressure is accurately contained at a predetermined value while the cylinder pressure (control pressure) is gradually reduced after the occurrence of the failure, the posture of the vehicle body is not greatly deteriorated.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, 10FL to 10RR denote front left to rear right wheels, 12 denotes a wheel side member connected to each wheel 10FL to 10RR, and 14 denotes a vehicle body side member. A hydraulic active suspension 16 is provided between each wheel side member 12 and the vehicle body side member 14.

The active suspension 16 includes a hydraulic pressure supply device 18 as a fluid pressure supply device, an operating pressure holding portion 20 and a fail safe valve (flow path switching valve) 22 which are interposed on the load side of the hydraulic pressure supply device 18, Accumulators 24, 24 provided on the load side of the fail-safe valve 22 corresponding to the front and rear wheels, and the wheel 1
Pressure control valves 26FL to 26RR equipped for 0FL to 10RR
And hydraulic cylinders (fluid cylinders) that are loads 28FL to 28
It has RR and. In addition, the active suspension 16
The vehicle behavior detector 30, a first controller 32 that gives command values I, ..., I to the pressure control valves 26FL to 26RR based on the detection signal of the detector 30, and each command value I by the first controller 32. Abnormal state detector 34 that monitors the value of
, F of the detection signal F of 34, and the 2nd controller 36 which carries out switching control of said fail safe valve 22. In the figure, 39 is a coil spring that supports the static load of the vehicle body.

The hydraulic supply device 18 includes a reservoir tank 40 that stores hydraulic oil, and a hydraulic pump 42 that uses an engine as a rotational drive source.
And a relief valve 44 for setting a predetermined line pressure.
That is, the supply side pipe (supply path) 48s for supplying the hydraulic oil to the tank 40 and the return side pipe (return path) 4 for returning the hydraulic oil to the tank 40
8r is connected, and the supply side conduit 48s reaches the operating pressure holding unit 20 of the next stage via the hydraulic pump 42. Further, a relief valve 44 is connected between the conduits 48s and 48r at a position on the discharge side.

The operating pressure holding means 20 is a check valve 50 inserted in the supply side conduit 48s and an operating check valve inserted in the return side conduit 48r and using the load side pressure of the fail-safe valve 22 as the pilot pressure P _P ( Open / close valve) 52. Operate check valve 52, the pilot pressure P _P1 set value (in this case, operates the neutral pressure P _N: see FIG. 4) to open the valve when exceeding uncheck, when: the neutral pressure P _N It has a pilot operated check valve structure that closes the valve for checking.

Also, a return line 48 upstream of the operation check valve 52 is provided.
r is provided with a bypass path 48B that is inserted through the stop 54 and bypasses the stop 54.

As shown, the fail-safe valve 22 is a check valve.
It is a 4-port 2-position electromagnetic switching valve in which the pump port P and the port A are connected to the supply side conduit 48s at the position downstream of 50 and the tank port T and the port B are connected to the bypass conduit 48B. When the switching signal CS provided to the electromagnetic solenoid 22 is off (when a failure occurs), the pump port P to the port A and the port B to the tank port T are connected.
When the switching signal CS is on (during normal operation) while the ports are cut off and the ports A and B are connected, the pump port P and the port A and the port B and the tank port T are mutually connected. It is designed to connect to.

Therefore, when the engine is not rotating, the discharge pressure of the hydraulic pump 42 is also zero, and the operating check valve 52
Is closed, the load side hydraulic path is sealed to the neutral pressure P _N by the operating check valve 52 and the check valve 50.
Further, assuming that the suspension is in the normal control state and the fail-safe valve 22 communicates the supply-side conduit 48s and the return-side conduit 48r individually, as will be described later, the discharge increases as the engine rotates. When the pressure exceeds the operating neutral pressure P _N , the operate check valve 52 opens and the relief valve
The line pressure determined by 44 is supplied to the load side.

Supply side pipeline 48s downstream of the fail-safe valve 22
Is branched corresponding to the front wheels 10FL, 10FR and the rear wheels 10RL, 10RR. Then, after each of the pipes 48s is connected to the accumulator 24 having a relatively large capacity, the pipes further branch off corresponding to the left and right wheels to reach supply ports of the pressure control valves 26FL to 26RR to be described later. Further, each return port of the pressure control valves 26FL to 26RR, which will be described later, merges with the left and right wheels and then merges with the front and rear wheels to reach the operation check valve 52, as shown in the figure.

On the other hand, each of the pressure control valves 26FL to 26RR is specifically, as shown in FIG. 2, a cylindrical valve housing 73 containing a valve body, and a proportional solenoid 74 integrally provided therein.
And have.

Spool insertion hole drilled in the center of valve housing 73
A main spool 75 is inserted into 73A, and a poppet valve 76 as a pilot valve is slidably inserted into a pilot valve insertion hole 73B formed coaxially with the insertion hole 73A at one axial end of the insertion hole 73A. doing. At both ends of the main spool 75,
A feedback chamber FR and a pilot chamber PR are formed respectively, and springs 77A and 77B for centering the spool 75 are provided in both chambers FR and PR. Here, 73Aa is a fixed throttle that allows the pilot chamber PR to communicate with the insertion hole 73B.

The valve housing 73 is provided with a land 75 of the main spool 75.
The supply port 73s, the return port 73r, and the output port are connected to the insertion holes 73A at positions opposing the pressure chambers 75a and 75b and the pressure chamber 75c.
Each has 73o. The pilot valve insertion hole 73B is provided with a valve seat 73Ba having a predetermined diameter that divides the insertion hole 73B in the axial direction.

The supply port 73s communicates with the pilot valve insertion hole 73B via the supply side passage 78, and the return port 73r has the drain side passage 79.
Through the passage hole 73B, and part of the hydraulic oil in the supply port 73s passes through the passage 78, the valve seat 73Ba, and the passage 79, and returns to the return port 73r.
Can be cycled to. At this time, the drain side passage 79 communicates with the insertion hole 73B at both end positions of the poppet valve 76, and also communicates with the inside of the proportional solenoid 74. In this embodiment, the supply-side passage 78, the valve seat 73Ba, the pilot valve insertion hole 73B, and the drain-side passage 79 form a pilot passage.

As shown in FIG. 3, the poppet valve 76 receives a thrust force from the proportional solenoid 74 and slides in the insertion hole 73B.
And a valve body 76B that is moved by being urged by the sliding body 76A. That is, the sliding body 76A is provided with a cylindrical recess 76Aa having an inner diameter larger than the outer diameter of the valve body 76B in the axial direction, and the valve body 76B abuts the recess 76Aa in a free and loose state. ing. Therefore, leakage can be reduced, and the axis of the poppet valve 76 can be easily taken out.

Further, the output port 73o communicates with the feedback chamber FR through the feedback passage 80, and this feedback chamber
FR communicates with the pilot valve insertion hole 73B through a bypass passage 81 formed by bypassing the spool 75. The connection position between the bypass passage 81 and the insertion hole 73B is such that when the poppet valve 76 takes the sliding position in the normal control state,
The sliding body 76A of 76 is an opening for the insertion hole 73B of the bypass passage 81.
When 81A is closed (that is, the bypass passage 81 and the insertion hole 73B are in a blocked state), and when the poppet valve 76 takes the sliding position in the fail state, the sliding body 76A exposes the opening 81A. The opening 81A is opened (that is, the bypass passage 81 and the insertion hole 73B are in communication with each other).

On the other hand, the proportional solenoid 74 includes a plunger 83 that can move in the axial direction, and an exciting coil 84 that drives the plunger 83.
Have and. When the exciting coil 84 is excited by the command value I, the plunger 83 moves to urge the sliding body 76A of the poppet valve 76, and the urging condition causes the valve seat 73B.
The pressure of the pilot chamber PR can be adjusted by adjusting the flow rate of hydraulic oil flowing through a.

The output port 73o is connected to a pressure chamber of a hydraulic cylinder 28FL (to 28RR) described later via a pipe 86. Further, in the figure, a to e are diaphragms.

Therefore, when the pressure of the proportional solenoid 74 is applied to the poppet valve 76 and the pressures of the feedback chamber FR and the pilot chamber PR are balanced, the spool 75 becomes the output port 73o and the supply port 73s and the return port 73r. The overlap position shown in FIG. Therefore, the pressure P _P2 of the pilot chamber PR is adjusted _{depending on} the magnitude of the command value I, and the spool 75 is slightly moved to perform the pressure adjusting operation until the pilot pressure P _P2 and the pressure P _F of the feedback chamber FR are balanced, and the output The output pressure P _c from the port 73o can be controlled in proportion to the command value I as shown in FIG. In the figure, P ₂ is the maximum line pressure from the hydraulic pressure supply device 8.

In addition, when there is a vibration input in the sprung resonance range (for example, around 1 Hz) of low frequency from the road surface side, and there is a hydraulic pressure fluctuation in the pressure chamber L of the hydraulic cylinder 28FL (~ 28RR) due to the vibration input. To do. This hydraulic pressure fluctuation is transmitted to the feedback chamber FR of the pressure control valve 26FL (to 26RR) via the pipe line 86, and the balance between the feedback pressure P _F and the pilot pressure P _P2 is lost.
In other words, if the vibration input is in the direction in which the suspension stroke expands and contracts, the feedback pressure P _F becomes the pilot pressure P
_It becomes higher than _P2 , the spool 75 moves upward, the communication between the output port 73o and the drain port 73r is established, and the hydraulic oil is returned to the tank 40. On the contrary, if the vibration input is in the direction in which the suspension stroke extends, the feedback pressure P _F becomes lower than the pilot pressure P _P2 , and the spool 75
Moves downward, and the supply port 73i and the output port 73o are brought into communication with each other, and hydraulic oil is supplied. That is, the hydraulic oil is circulated by the slight movement of these spools 75, and the pressure fluctuation up to a predetermined limit is absorbed.

Further, as shown in FIG. 1, each of the hydraulic cylinders 28FL to 28RR has a cylinder tube 28a, and a lower pressure chamber L separated by a piston 28c is formed in the cylinder tube 28a. And the cylinder tube 28a
Is attached to the wheel side member 12 and the piston rod
The upper end of 28b is attached to the vehicle body side member 14. Further, the pressure chamber L of each hydraulic cylinder 28FL to 28RR has a throttle valve 90
Is connected to a small-capacity accumulator 91 for absorbing hydraulic vibration in the unsprung resonance region (for example, 5 to 10 Hz).

On the other hand, the vehicle behavior detector 30 is mounted at a predetermined position on the vehicle body, detects lateral, longitudinal, vertical accelerations and the like of the vehicle body and outputs electric signals corresponding to these state quantities to the first controller 32. It is supposed to do. The first controller 32 has a well-known configuration including an A / D converter, a microcomputer, a D / A converter, and a drive circuit as a main part (for example, Japanese Patent Laid-Open Publication No. 63-63)
-125419)), and the command value I, ..., I corresponding to the detection signal in the microcomputer, which is the current value for suppressing and attenuating the posture variation, is in the range of I _{1 to} I ₂ (see FIG. 4). .., I are given to the proportional solenoid 74 of the pressure control valves 26FL to 26RR via the drive circuit.

Here, the vehicle behavior detector 30 and the first controller 32
Constitutes the attitude control means.

The abnormal state detector 34 is a current / voltage converter that detects the command value I actually output from each drive circuit of the first controller 32 as a voltage value, and the conversion value F is sent to the second controller 36. Output. The second controller 36 is configured in the same manner as the first controller 36, and in the microcomputer thereof, the value of the command value I is calculated based on the input voltage signal F, and the magnitude of the calculated value is determined for each wheel. The switching control signal CS is controlled to be turned on and off based on the judgment. That is, the second controller 36 controls the pressure control valves 26FL to 26RR.
The switching signal CS is turned off when any of the actual current values I is a value (I ₁ <I <0) that cannot be taken in the normal attitude control state, and is turned on otherwise. .

Here, the abnormal state detector 34 and the second controller 36
Constitutes an abnormal condition judging means. In addition, the above-mentioned
The first and second controllers 32 and 36 may share the same microcomputer.

 Next, the operation of the first embodiment will be described.

Now, it is assumed that the vehicle is in a traveling state and that the harness for giving a power down or a command value is in a normal state without a break or the like.

In this state, the abnormal state detector 34 determines that the command value I is the lowest value.
The signals F, ..., F corresponding to the range from I ₁ to the maximum value I ₂ are detected and output to the second controller 36. For this reason,
Since the second controller 36 turns on the switching signal CS as described above, the exciting coil of the electromagnetic solenoid 22A of the fail-safe valve 22 is in the excited state. As a result, the pump port P and the port A and the tank port T and the port B are connected to each other as described above, and the supply side conduit 48s and the return side conduit 48r (the throttle 54 is bypassed by the conduit 48B). Are communicated with each other. That is, in this traveling state, the operation check valve 52 is open, and the posture control is possible.

Then, when the vehicle is traveling without good road irregularities at a constant speed, since the body will not be swung, the detection signal is zero vehicle behavior detector 30, the command value I = I _N, and the this the pressure control unit 26FL~26RR supplies a neutral pressure P _N which corresponds to the command value I _N in the pressure chamber L of the hydraulic cylinder 28FL~28RR by. Therefore, the vehicle body takes a flat posture with a constant vehicle height value due to the neutral pressure P _N.

From this state, the vehicle is traveling on a swell or bad road where large amplitude of low frequency continues, and the vibration input in the sprung resonance region is the hydraulic cylinder.
It is assumed that the data is transmitted to 28FL to 28RR. The hydraulic pressure fluctuation due to this vibration occurs with a relatively large flow rate change, and as described above, the spool 75 of the pressure control valves 26FL to 26RR is finely moved in the axial direction to transfer the hydraulic oil to the hydraulic pressure supply device 18. Distribute and absorb vibration.

However, when the vibration continues for a long time or the like, and the vibration cannot be completely absorbed by the fine movement of the spool 75 of the pressure control valves 26FL to 26RR, the vehicle body also tries to swing up and down. State quantity related to this swing (acceleration, etc.)
Change is detected by the vehicle behavior detector 30, the first controller 32 supplies the command values I for controlling and damping the swing of the vehicle body to the pressure control valves 26FL to 26RR, respectively, as described above. Therefore, since the pressure control valves 26FL to 26RR output the pressure P _c corresponding to the command value I to the hydraulic cylinders 28FL to 28RR, respectively, the hydraulic cylinders 28FL to 28RR generate a force for controlling and damping the bounce, which causes The vehicle body can be positively held in a flat posture, and thus a good riding comfort can be maintained.

Next, an example when a failure occurs will be described with reference to FIG. The example of the figure shows the pressure change related to the failure occurrence in the state where the roll control is performed for the turning traveling,
In the figure, P _s is the supply pressure, P ₀ is the outer ring pressure (the working pressure of the outer ring side hydraulic cylinder), P _i is the inner ring pressure (the working pressure of the inner ring side hydraulic cylinder), P _N is the neutral pressure, P _Fi , P _Fo is the pressure in the feedback chamber FR in the pressure control valve on the inner ring side and the pressure on the outer ring side, and P _R is the back pressure.

The vehicle behavior detector 30 detects lateral acceleration associated with turning, and the first controller 32 controls the roll acceleration based on the lateral acceleration.
, I is calculated for each of the left and right wheels and output to each pressure control valve. As a result, the outer ring pressure P ₀ > P _N and the inner ring pressure P _i <P _N ,
Roll rigidity is enhanced, body roll is suppressed, and the body posture is almost flat. At this time, as for the pressures P _Fi and P _Fo in the feedback chamber FR, the opening 81A has a poppet valve 7
Blocked by 6, each hydraulic cylinder 28FL
It is equal to the operating pressure of ~ 28RR. In this state, at time t ₀ , each pressure control valve is released from the first controller 32.
It is assumed that one of the outer-wheel side harnesses for command value transmission that is routed in the vehicle body from 26FL to 26RR is dropped or broken due to long-term vibration or the like.

As a result, the outer ring side pressure control valves 26FL, 26RL (or 26FR,
26RR) command value I becomes zero, the thrust by the proportional solenoid 74 disappears in steps, and the poppet valve 76 is inserted into the insertion hole 73.
Immediately retreat inside B to the proportional solenoid 74 side. Therefore, the opening 81A of the bypass passage 81 is exposed, and the feedback chamber FR and the pilot valve insertion hole 73B, that is, the return port 73r communicate with each other, and the pilot chamber PR and the return port 73r communicate with each other. As a result, both the feedback pressure P _F and the pilot pressure P _P2 become equal to and equal to the back pressure P _R , and the spool 75 is centered. Therefore, the control pressure P _C of the output port 73o, that is, the cylinder pressure, becomes the spool 75. The pressure higher than the neutral pressure P _N is temporarily contained (see outer ring pressure P _{0 in} FIG. 5). That is, it is possible to reliably eliminate a sudden change in cylinder pressure when a failure occurs, that is, a sudden change in the vehicle body posture, as in the conventional case. Moreover, since the structure only provides the bypass flow passage 81 at a predetermined position,
It is simple and increases in processing costs can be minimized.

After that, the working oil on the outer ring side, which is temporarily contained as described above, gradually reaches the feedback chamber FR via the throttle d of the feedback passage 80, and the bypass passage 81, the insertion hole 73B,
Since it returns to the return port 73r via the drain side passage 79,
As indicated by the outer wheel pressure P ₀ in FIG. 5, the control pressure P _C also begins to gradually decrease.

On the other hand, on the fail-safe valve 22 side, the following flow path switching control is performed in parallel with the spool centering control described above. That is, when the actual current value I of the pressure control valve suddenly drops below I ₁ , this sudden drop is immediately detected by the abnormal state detector 34. The second controller 36 determines that a failure has occurred at the time t ₁ , and switches the switching signal CS from the previous ON to OFF. Here, from t ₀ when fail occurs
The reason why there is a time delay until t ₁ is that there is a slight time delay in the decrease of the current value due to the inductance component of the solenoid of the pressure control valve. Therefore, since the switching is energized, the ports P to A and T to B of the fail-safe valve 22 are shut off, and the ports A to B are in a communication state.
The hydraulic oil accumulated in the conduit 48s between the fail safe valve 22 and the pressure control valves 26FL to 26RR and each accumulator 24 positively returns to the return side conduit 48r. As a result, the supply pressure P _s
Gradually decreases and the back pressure (return pressure) P _R is reduced by 54
Due to the presence of the noise, it rises sharply as shown in FIG.

After that, even if the back pressure P _R rises, the back pressure P _R , the feedback pressure P _F , and the pilot pressure P _P2 become the same pressure successively, so that the centering of the spool 75 is maintained and the cylinder pressure does not suddenly change. Or, the rise of the back pressure P _R makes the decrease of the control pressure P _C slower.

On the contrary, on the inner ring side, the pressure control valve can operate in a normal mode, and the back pressure P _R is applied to the back surface of the plunger 83 via the orifice e from the time t ₁ when the back pressure P _R rises. The inner ring pressure P _i gradually increases as shown in FIG.

On the other hand, the hydraulic oil that has been turned to the return side gradually escapes to the tank 40 via the throttle 54 and the operation check valve 52 with the lapse of time, so the supply pressure P _s gradually decreases to the neutral pressure P _N. At that time, the operation check valve 52 is closed.
With this, the supply pressure P _s = return pressure P _R = control pressure P _C is confined on the load side with the neutral pressure P _N , and the sealed state can be maintained for a long time.

At this time, the hydraulic oil on the supply side is sent to the return side to positively build up the back pressure, so the hydraulic oil from the cylinder escapes slowly on the outer ring side, and at the same time the hydraulic oil to the cylinder on the inner ring side Promote the influx of. That is, when viewed from the operating check valve 52, the pilot pressure P _P1 (=
The decrease in the supply pressure P _s ) is not limited to the decrease in the line pressure,
Since it is a state that accurately reflects the pressure drop of the entire load side circuit, precise operating pressure filling is performed, and it is possible to reliably avoid the fact that the filled pressure is actually less than _PN , and the vehicle height value is insufficient. It can be prevented.

In this way, even if an abnormality occurs, the sudden change in the vehicle body posture is eliminated and the subsequent traveling is possible. In particular, even when an abnormality occurs in the command value system corresponding to the turning outer wheel side during turning, the fail-safe function described above causes the turning outer wheel side to suddenly sink to the minimum stroke, making the posture extremely unstable. It is possible to reliably avoid the situation where it becomes difficult to operate, and it does not give unnecessary unease to the occupants. This fail-safe function works similarly when two or more harnesses are simultaneously broken.

On the other hand, when the ignition switch is turned off, the rotation of the hydraulic pump 42 is stopped, the power supply is stopped, the command value I is zero, and the switching signal CS is turned off. As a result, in the case where the normal state before the stop, the operation check valve 52 is closed as the line pressure P _s is decreased, and the load side neutral pressure P _N To ensure a flat posture with a constant vehicle height,
If there is an abnormal state before the stop, the load side is continuously contained in the neutral pressure P _N.

The device to which the fluid pressure cylinder according to the present invention is applied is not necessarily the active suspension of the vehicle as described above, and may be another device such as a hydraulic jack.

Further, in the embodiment corresponding to the active suspension according to claim (3), the working pressure is enclosed in the neutral pressure after the sudden change of the vehicle body is suppressed when the failure occurs. When the state detector 34, the second controller 36, the fail-safe valve 22, the throttle 54, and the conduit 48B are removed, the configuration corresponding to the active suspension according to claim (2) can be obtained, and the pressure control is simply performed. It is possible to obtain a simple fail-safe effect of preventing a sudden change in the vehicle body posture when a failure occurs in the valves 26FL to 26RR.

Furthermore, in the above-described embodiment, as a configuration for detecting the occurrence of an abnormal state, the power supply voltage of the first controller 32 may be monitored, and the above-mentioned fail-safe mechanism may be activated when the power supply fails. As a result, the same effect as described above can be obtained.

Furthermore, the working fluid of the present invention is not necessarily limited to the working oil described above, and may be any fluid having a low compression rate.

〔The invention's effect〕

As described above, the pressure control valve according to claim (1) uses the backward movement of the pilot valve due to the disappearance of the biasing force from the proportional solenoid to the pilot valve when a failure occurs, and the pressure control valve passes through the bypass passage. Since the feedback chamber and pilot chamber at both ends of the spool are made to communicate with each other, the pressure applied to both ends of the spool can be maintained at the same pressure, which allows the spool to be centered at the neutral position, resulting in a failure and zero command value. When
It is possible to temporarily hold the working pressure immediately before the occurrence of a failure, thereby reliably avoiding a situation where the working pressure of the fluid pressure cylinder suddenly drops or rises, and it is possible to prevent sudden changes in the posture of the target device to which the fluid pressure cylinder is applied. There is an effect. Further, in order to obtain this effect, since the bypass flow path is simply provided at a predetermined position, the structure is simple, and the production cost can be suppressed from increasing, and there is an advantage that mechanical failure is small. .

Further, in the active suspension according to claim (2), a sudden change in the vehicle body posture when a failure occurs can be reliably eliminated in the same manner as described above, so that adverse effects such as deterioration of maneuverability on traveling can be minimized. In addition, it is possible to obtain an excellent fail-safe effect that does not give the passenger anxiety.

Further, in the active suspension according to claim (3), in addition to the above-mentioned advantages, the working pressure can be enclosed to a predetermined value when a failure occurs, so that a suboptimal vehicle body posture based on the predetermined pressure can be secured even after the failure occurs. Further, the reliability of the fail-safe effect can be remarkably improved such that the vehicle can continue traveling thereafter.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 2 is a sectional view showing the structure of the pressure control valve in FIG. 1, and FIG. 3 is a structure of a poppet valve in the pressure control valve. FIG. 4 is a cross-sectional view, FIG. 4 is a graph showing an output pressure characteristic with respect to a command value of the pressure control valve, and FIG. 5 is a graph showing an example of pressure fluctuation when a failure occurs. In the figure, 12 is a wheel side member, 14 is a vehicle body side member, 16 is an active suspension, 18 is a hydraulic pressure supply device (fluid pressure supply device),
22 is a fail-safe valve (flow path switching valve), 26FL to 26RR are pressure control valves, 28FL to 28RR are hydraulic cylinders (fluid pressure cylinders), 34 is an abnormal state detector, 36 is a second controller,
48s is a supply side pipeline, 48r is a return side pipeline, 52 is an operating check valve (open / close valve), 73 is a valve housing, 73A is a spool insertion hole, 73B is a pilot valve insertion hole, 73Ba is a valve seat, 73
s, 73r, 73o are supply port, return port, output port, 74
Is a proportional solenoid, 75 is a spool, 76 is a poppet valve (pilot valve), 78 and 79 are supply side and return side passages, 80 is a feedback passage, 81 is a bypass passage, and 81A is an opening.

Claims (3)

[Claims] 1. A supply port connected to a fluid pressure supply device,
A valve housing having a return port and an output port connected to a fluid pressure cylinder, a spool arranged in an insertion hole in the valve housing in a zero-wrapped or overlapped state, and a pilot provided on one end side of the spool. A pilot channel that communicates between the supply port and the return port in a state of communicating with the chamber and a thrust of a proportional solenoid that is driven based on a command value to move in the pilot channel and adjust the pressure in the pilot chamber Pilot valve to
A feedback chamber that is provided on the other end side of the spool and communicates with the output port, and a bypass flow passage that communicates between the feedback chamber and the pilot flow passage by bypassing the insertion hole, and the bypass flow passage is provided. When the command value is a normal value, the pilot valve closes the opening part value to the pilot flow path, and when the command value is an abnormal value, the pilot valve is A pressure control valve characterized in that the opening is set at a position where it is exposed. 2. A fluid pressure cylinder interposed between a vehicle body and wheels, and a supply pressure supplied from a fluid pressure supply device to the fluid pressure cylinder is controlled in accordance with a command value for correcting a posture change of the vehicle body. An active suspension including a pressure control valve, wherein the pressure control valve includes a valve housing having a supply port connected to the fluid pressure supply device, a return port, and an output port connected to the fluid pressure cylinder. A spool disposed in the insertion hole in the valve housing in a zero-wrapped state or an overlapped state, and a pilot channel for communicating between the supply port and the return port in a communicating state with a pilot chamber provided on one end side of the spool. A pyrolyzer which moves in the pilot flow path and is adjusted by the thrust of a proportional solenoid driven based on a command value to adjust the pressure in the pilot chamber. A shutoff valve, a feedback chamber that is provided at the other end of the spool and communicates with the output port, and a bypass channel that bypasses the insertion hole and communicates between the feedback chamber and the pilot channel. When the command value is a normal value, the pilot valve closes the opening of the bypass flow path to the pilot flow path, and when the command value is an abnormal value, An active suspension characterized in that the pilot valve is set at a position where the opening is exposed. 3. A fluid pressure cylinder interposed between a vehicle body and a wheel, and a supply pressure supplied from a fluid pressure supply device to the fluid pressure cylinder is controlled according to a command value for correcting a posture change of the vehicle body. An active suspension including a pressure control valve, wherein the pressure control valve includes a valve housing having a supply port connected to the fluid pressure supply device, a return port, and an output port connected to the fluid pressure cylinder. A spool disposed in the insertion hole in the valve housing in a zero-wrapped state or an overlapped state, and a pilot channel for communicating between the supply port and the return port in a communicating state with a pilot chamber provided on one end side of the spool. A pyrolyzer which moves in the pilot flow path and is adjusted by the thrust of a proportional solenoid driven based on a command value to adjust the pressure in the pilot chamber. A shutoff valve, a feedback chamber that is provided at the other end of the spool and communicates with the output port, and a bypass channel that bypasses the insertion hole and communicates between the feedback chamber and the pilot channel. When the command value is a normal value, the pilot valve closes the opening of the bypass flow path to the pilot flow path, and when the command value is an abnormal value, A structure in which the pilot valve is set at a position where the opening is exposed, and an abnormal state determination unit that determines an abnormal state of the command value,
A flow path switching valve that disconnects the fluid pressure supply path to the pressure control valve when the abnormal state determination means determines that the command value is abnormal, and connects the load side of the blocked supply path to the return path.
An active suspension, comprising: an opening / closing valve that shuts off the return path when the supply pressure to the pressure control valve decreases and is below a predetermined value.