JP2502371B2 - Active suspension - Google Patents

Description

Description: [Industrial field of application] The present invention has a fluid pressure cylinder that is individually interposed between a vehicle body and each wheel, and the working pressure of each fluid pressure cylinder is used to change the posture of the vehicle body. According to the active suspension that is actively controlled according to the above, especially when an abnormality (fail) occurs due to a disconnection of the electric system, a power supply down, etc.
The present invention relates to an active suspension having a fail-safe function capable of accurately dealing with the abnormality.

[Conventional technology]

Conventionally, as an active suspension, for example, one disclosed in Japanese Patent Application Laid-Open No. 63-219408 already proposed by the present applicant is known.

In this conventional active suspension, a hydraulic cylinder arranged on each wheel, a hydraulic supply device for supplying an operating pressure to the hydraulic cylinder, and the operating pressure in accordance with a command value (current value) from an attitude change control device. With a pressure control valve to control,
A check valve is installed in the pressure control valve supply passage, and a pilot operated check valve that closes only in the return passage when the supply pressure of the hydraulic pressure supply device is below a predetermined pressure, and this check valve. A relief valve that holds the pressure on the upstream side of the valve at a predetermined value is interposed in parallel. That is, when the rotation of the engine is stopped, the discharge pressure of the hydraulic pump of the hydraulic pressure supply device immediately becomes zero. Therefore, when the supply pressure decreases and becomes equal to or lower than the predetermined pressure, the pilot operated check valve closes. Become. Thereby, the load side paths of the check valve and the pilot operated check valve are confined at the predetermined pressure of the pilot operated check valve so that the vehicle height value does not change suddenly.

[Problems to be Solved by the Invention]

By the way, in such an active suspension, the hydraulic pressure source and the attitude control command means are respectively arranged at predetermined positions of the vehicle body, but the respective pressure control valves are distributed and individually arranged corresponding to the cylinder position. As a result, the harness that supplies the command value becomes long, and the inside of the vehicle body is sewn between other structural parts in a complicated manner, which causes loosening of the connection part due to vibration, etc., and power down. In addition, there was a risk that an abnormality (failure) such as disconnection would occur.

However, the conventional active suspension has a structure in which the operating pressure is contained only when the engine is stopped to maintain the vehicle height value, and the above-described abnormality occurrence is not particularly taken into consideration. Occurs and the current value in the pressure control valve suddenly changes to zero,
There was an unsolved problem that not only would the passengers feel anxious due to such sudden changes in the vehicle body posture, such as the outer wheel side suddenly sinking to the minimum stroke, but there was also the case of having to give up further driving. .

The present invention has been made by paying attention to such an unsolved problem of the conventional technique, and when an abnormality occurs in the system that gives a command value, the back pressure of the pressure control valve is immediately raised to near the supply pressure. Raise the operating pressure to prevent it from returning to the fluid pressure source, and then gradually contain the operating pressure at a predetermined value to prevent sudden changes in the vehicle body posture and to ensure a vehicle body posture that allows the vehicle to continue running. , The problem to be solved.

[Means for solving the problem]

In order to solve the above problems, in the invention according to claim (1), a fluid pressure cylinder interposed between a vehicle body and a wheel,
An active suspension equipped with a control valve for controlling a working fluid pressure from a fluid pressure source supplied to the fluid pressure cylinder through a supply passage and a return passage according to a command value for correcting the posture change of the vehicle body. In the above, a check valve installed in the supply passage, an on-off valve installed in the return passage and closed when the supply pressure on the downstream side of the check valve is equal to or less than a predetermined value, and an upstream of the on-off valve. A stop provided on the side, an abnormal state determination means for determining an abnormal state of the suspension, and a bypass path bypassing the throttles of the supply path and the return path so that the abnormal state determination means is normal. When the status is judged, the supply path and the bypass path are communicated with each other, and when the abnormal status is judged, the supply path and the bypass path are shut off respectively, and the downstream side and the bar of the supply path are closed. A fail-safe valve that communicates the upstream side of the pass path, wherein the fail-safe valve has first to third ports that communicate with the downstream side, the upstream side of the supply path, and the downstream side of the bypass path, respectively. A valve housing formed in order and having a fourth port communicating with the upstream side of the bypass passage, a movable body slidably inserted into an insertion hole in the valve housing, and the judgment by the abnormal state judging means. A driving unit that moves the moving body in a direction in which the third port is closed when the result is in an abnormal state, and a moving direction length of the moving body is set between the first and third ports. It is formed larger than the length in the moving direction including the port diameter.

Further, in the invention according to claim (2), in the configuration according to claim (1), the moving body is formed on an outer peripheral surface facing the first and second ports, respectively. A convex part,
A concave portion formed between the both convex portions and continuous with the first convex portion,
One has a flow path that opens at an adjacent position on the opposite side of the concave portion of the first convex portion and the other communicates with the fourth port, and the moving direction length of the first convex portion is The diameter of the first port is smaller than that of the first port.

[Action]

It is now assumed that the vehicle is in a traveling state, the fluid pressure source is supplying a predetermined line pressure, and there is no abnormality in the system that gives a command value to the control valve. In this normal state, the supply pressure to the control valve is higher than the predetermined value for containing the operating pressure, so the open / close valve is in the "open" state, and the abnormal state determination means has not determined the abnormal state. The drive unit of the fail-safe valve urges the moving body in the direction of opening the third port. In other words, with the fail-safe valve,
The second port and the first port of the valve housing communicate with each other through the groove of the moving body, and the fourth port and the third port communicate with each other, so that the supply path and the bypass path, that is, the return path are in communication with each other. is there. Therefore, the working fluid from the fluid pressure source reaches the control valve side via the check valve, and the return fluid from the control valve side returns to the fluid pressure source via the operate check valve.

In this normal state, the operating pressure of the fluid pressure cylinder is controlled by the control valve, and a force or a damping force that resists the posture change of the vehicle body is generated.

In this state, assume that an abnormal state such as a wire breakage has occurred in the harness that transmits the command value. With this,
Since the abnormal state determination means immediately determines the abnormal state and notifies the drive unit of the failsafe valve, the drive unit moves the moving body in the direction of closing the third port. At the time of this movement, first, the third port of the valve housing is always blocked by the second convex portion at the tip of the moving body (blocking of the return path), and thereafter, blocking (supply of the first port and second port). (Blocking of the passage) and communication through the flow paths of the first port and the fourth port (communication between the downstream side of the supply path and the upstream side of the bypass path)
And are done.

For this reason, the high-pressure hydraulic oil that has accumulated on the load side of the supply path flows into the drain port side of the control valve because there is a throttle on the downstream side after entering the return path, and the back pressure is quickly supplied. Start up to near pressure, then gradually throttle and return to the fluid pressure source via the on-off valve. As a result, the opening / closing valve closes and the working oil is confined when the supply side pressure of the control valve falls to a predetermined value. Therefore, there is no room for the high-pressure hydraulic oil accumulated on the load side of the supply passage to return to the fluid pressure source via the bypass passage, the return passage, and the open / close valve in the event of an abnormality, so that the load side is highly accurate. It can be contained quickly with a predetermined pressure, and a minimum body posture can be secured at the time of failure.

Particularly, in the invention described in claim (2), when the moving body moves when an abnormality occurs, the communication between the fourth port and the third port is first blocked (return path blocking: first procedure),
Next, communication between the first and second ports and the fourth port (connecting the downstream side of the supply path and the upstream side of the bypass path: the second procedure),
Finally, the first port and the second port are sequentially disconnected from each other (interruption of the supply path: the third procedure) to complete the switching. That is, between the second procedure and the third procedure, there is a time zone in which the supply path from the fluid pressure source to the control valve and the upstream side (control valve side) of the throttle in the return path are in communication at the same time. That is, during this time period, high-pressure hydraulic oil is supplied to the return side not only from the supply passage but also from the fluid pressure source, and the back pressure of the control valve rises more reliably and quickly. And the responsiveness is improved.

〔Example〕

First Embodiment Hereinafter, a first 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 is a hydraulic pressure source as a fluid pressure source.
18, a working pressure holding means 20 and a failsafe valve 22 which are provided on the load side of the hydraulic power source 18, and the failsafe valve
Accumulators 24 and 24, which are equipped on the load side of 22 to correspond to the front and rear wheels and contain a large volume of high-pressure gas, and wheels 10FL to 10RR on the load side of the accumulators 24 and 24, respectively. Equipped with pressure control valves 26FL to 26RR, and hydraulic cylinders (fluid cylinders) 28FL to 28RR that are loads individually interposed between the vehicle body side member 14 and each wheel side member 12. . Further, the active suspension 16 is a vehicle behavior detector 30 that detects the behavior of the vehicle body in the form of an electric signal, and a command value I that is a current value for the pressure control valves 26FL to 26RR based on the detection signal of this detector 30. ..., I is given to the pressure control valve 26FL ~
First controller 32 that individually controls the output pressure P _{c of} 26RR
, An abnormal state detector 34 for monitoring the command values I, ..., I by the first controller 32, and the switching operation of the fail-safe valve 22 based on the detection signals F, ..., F of the detector 34. And a second controller 36 for controlling the. Further, a coil spring 39 having a relatively low spring constant and supporting a static load of the vehicle body is provided between the wheel side member 12 and the vehicle body side member 14, respectively.

The hydraulic pressure source 18 includes a reservoir tank 40 for storing hydraulic oil.
And a relief pump 44 for setting a predetermined line pressure. A supply side conduit (supply path) 48s for supplying hydraulic oil to the tank 40 and a return side conduit (return path) 48r for returning hydraulic oil.
And the supply side pipeline 48s reaches the working pressure holding means 20 of the next stage via the hydraulic pump 42, and the pipelines 48s, 48r
A relief valve 44 is connected between them.

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 ( And an on-off valve) 52. In the operating check valve 52, the pilot pressure P _P is set to a set value (here, the operating neutral pressure of each pressure control valve 26FL to 26RR).
When it exceeds P _N ), the valve is opened, the check is released and opened, and when the neutral pressure is P _N or less, the valve is closed and the check is performed.

In addition, the return side pipeline upstream of the operate check valve 52
A diaphragm 54 is interposed at 48r.

The fail-safe valve 22 includes the supply-side conduit 48s and the throttle 5
It consists of a 4-port electromagnetic switching valve installed in the middle of a bypass pipe (bypass) 48B that bypasses 4. In particular,
As shown in FIG. 2, it has a valve body 56 and an electromagnetic solenoid 57 integrally attached to the valve body 56. The valve main body 56 includes a substantially cylindrical valve housing 58 and a spool (moving body) 59 slidable inside a hollow insertion hole 58A formed inside the valve housing 58. Valve housing
The first port T having a circular cross section communicates with the insertion hole 58A along the axial direction (direction of arrow A in FIG. 1) of the 58.
_{The first} port ₂ , the second port T ₂ , and the third port T ₃ are sequentially formed from the left side in FIG. 2, and the communication hole 58 on the right end side in FIG.
The opening continuing from A is assigned to the fourth port T ₄ . Of these, the first and second ports T ₁ and T ₂ are connected to the downstream side and the upstream side of the supply side pipeline 48s, respectively, and the third and fourth ports T ₃ and T _{4 are connected.}
Are connected to the downstream side and the upstream side of the bypass pipeline 48B, respectively.

Further, the spool 59 has a hollow portion 59A which is bored in the inner axial direction and is open at least on the right end side in FIG.
An opening 61 that opens to the outer peripheral surface is formed at a predetermined position on the left end side that can face the first port T ₁ . Further, a groove portion having a concave axial cross section over a predetermined axial range that can face the first and second ports T ₁ and T ₂ on the outer peripheral surface of the spool 59.
62 is formed, and by the formation of the groove portion 62, first and second convex portions 63, 64 having a rectangular axial cross section are formed at both axial ends of the groove portion 62.
Are continuously formed.

Here, in this embodiment, the first and second spools 59 are provided.
Axial length a including the convex portion between the convex portions 63 and 64, and axial length b from the first port T ₁ to the third port T ₃ of the valve housing 58 (including the diameters of both ports). As will be described later, a relation of a> b is provided between the _first and _third ports so that the first, third and fourth ports T ₁ , T ₃ and T ₄ are not in the communicating state at the same time. Also, the axial length c of the first convex portion 63 of the spool 59,
In order to obtain a state in which the first, second, and fourth ports T ₁ , T ₂ , T ₄ are simultaneously in communication with the diameter d of the first port T ₁ of the valve housing 58, as will be described later, d > C has a relationship.

On the other hand, the electromagnetic solenoid 57 includes a housing 66 having a hollow portion 66A that opens toward the valve body 56 and a housing 66
Excitation coil 67 wound around the outer periphery of 6, fixed portion 66B fixed in housing 66 inside hollow portion 66A, and hollow portion 66A
It has an actuator 68 that can move in the axial direction, and a return spring 69 interposed between the actuator 68 and the fixed portion 66B. Then, the outer periphery of one end of the valve housing 58 is integrally clamped at one end of the hollow portion 66A of the housing 66 as shown in the figure, and the attachment end 59B of the left end of the spool 59 is attached to the right end of the actuator 68 in the figure. Are held together.

Therefore, when the switching control signal CS supplied to the electromagnetic solenoid 57 is turned on (during normal control) and the exciting coil 67 is in the excited state, the actuator 68 is attracted to the left end side in FIG. Also moves to the left end side to take the spool position shown in the figure. On the contrary, when the switching control signal CS is off (at the time of abnormality), the exciting coil 67 is in the non-excited state and the attraction force to the actuator 68 is released, so that the spring force of the return spring 69 causes the actuator 68 to move to the second position. The actuator 68 is pushed to the right end side in the drawing and moves to a position where the actuator 68 comes into contact with the end face of the valve housing 58 (fifth position).
See FIG. (D)). As a result, the passages are switched as will be described later.

In the above, when the engine is not rotating,
Since the discharge pressure of the hydraulic pump 42 is also zero and the operate check valve 52 is closed, the load side hydraulic path of the both valves 52 and 50 is maintained at the neutral pressure P _N by the operate check valve 52 and the check valve 50. It 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 bypass conduit 48B individually, as will be described later, the discharge pressure that rises as the engine rotates. When the operating neutral pressure P _N exceeds the operating neutral pressure P _N , the operate check valve 52 opens, and the line pressure determined by the relief valve 44 is supplied from the hydraulic pressure source 18 to the load side.

On the load side of the fail-safe valve 22, the supply line 48
s is branched corresponding to front wheels 10FL, 10FR, rear wheels 10RL, 10RR,
Each of the pipes 48s is connected to the accumulator 24, and further branches corresponding to the left and right wheels to reach the supply ports of the pressure control valves 26FL to 26RR described later. In addition, the operating check valve 52
As shown in the figure, front and rear and left and right branches between the pressure control valves 26FL to 26RR and a drain port described later.

In addition, at a predetermined position of the return side pipe line 48r connected to the drain ports of the left and right pressure control valves 26FL, 26FR and 26RL, 26RR,
The accumulators 70, 70, which have a small capacity and are filled with low-pressure gas, are connected.

On the other hand, each of the pressure control valves 26FL to 26RR is, as specifically shown in FIG. 3, a cylindrical valve housing containing a valve body.
It has a 76 and a proportional solenoid 77 provided integrally therewith.

In the center of the valve housing 56, an upper insertion hole 76U and a lower insertion hole 76L in the figure, which are defined by a partition wall 76A having a valve seat 76c of a predetermined diameter, are coaxially formed. A fixed diaphragm 78 is provided above the insertion hole 76L and below the partition wall 76A by a predetermined distance.
A pressure chamber C is formed between 78 and the partition wall 76A. A main spool 79 is disposed below the fixed throttle 78 in the insertion hole 76L so as to be slidable in the axial direction, and above and below the main spool 79, the pilot chamber F _U and the feedback chamber F _L. Are formed respectively. Further, the upper and lower ends of the main spool 79 is biventricular F _U, each arranged to F _L are centering springs 80A, is regulated by 80B. And
A supply port 76i, an output port 76o, and a drain port 76r are formed to communicate with the insertion hole 76L in this order, the supply port 76i is connected to the supply side pipe 48s, and the drain port 76r is connected to the return side pipe 48.
Further, the output port 76o is connected to the pressure chamber L of the hydraulic cylinder 28FL (to 28RR) via the conduit 82.

The main spool 79 includes a land 79a that faces the supply port 76i, a land 79b that faces the drain port 76r, a pressure chamber 79c formed by an annular groove formed between these lands 79a and 79b, and the pressure chamber 79c and Lower feedback room _FL
And a pilot passage 79d that communicates with the.

Further, in the upper insertion hole 79U, a poppet 83 is disposed slidably in the axial direction with the valve portion facing the valve seat 76c, and the poppet 83 serves to protect the hydraulic oil flowing through the valve seat 76c. The flow rate, that is, the pressure in the pressure chamber C (= pilot chamber F _U ) can be adjusted.

Furthermore, the input port 76i communicates with the pressure chamber C via a pilot passage 76s, and the drain port 76r communicates with the insertion hole 76U via a drain passage 76t.

On the other hand, the proportional solenoid 77 includes an axially slidable plunger 87 and an actuator fixedly mounted on the plunger 87.
It has 87A and an exciting coil 88 for driving the plunger 87 in its axial direction, and this exciting coil 88 is appropriately excited by a command value I which is a current value. That is, the movement of the plunger 87 controls the position of the poppet 83 via the operator 87A, and controls the flow rate passing through the partition wall 86A.

Therefore, the pressing force of the proportional solenoid 77 is
While being applied to 83, the chambers F _L, the pressure in the F _U are balanced, the spool 79 is in the neutral position, the blocking between the output port 76o and the supply port 76i and the drain port 76r (shown spool Position). Therefore, the pressure in the pilot chamber C can be controlled by the magnitude of the command value I, and the spool 59 is slightly moved to perform the pressure adjusting operation until the pressures in the feedback chambers F _L and F _U are balanced based on the pilot pressure, and the output is output. The output pressure P _c from the port 76o can be controlled. That is, as shown in FIG. 4, when the command value I is less than or equal to I _MIN , P _MIN is output, and when the command value I increases in the positive direction from this state, a predetermined proportional gain K ₁ is output to this. When the pressure P _c increases and reaches the maximum line pressure P _MAX, it is saturated.

Further, it is assumed that there is a vibration input in a sprung resonance region (for example, about 1 Hz) which is a low frequency from the road surface side, and that the vibration input causes a hydraulic pressure fluctuation in the pressure chamber L of the hydraulic cylinder 28FL (to 28RR). . The oil pressure change is transmitted to the feedback chamber F _L of the pressure control valve 26FL (~26RR) via line 82, both chambers
F _L, the pressure balance of F _U collapse. In other words, if the vibration input is such that the suspension stroke expands and contracts, the pressure in the feedback chamber F _L becomes higher than the pressure in the pilot chamber F _U , the spool 79 moves upward, and the pressure between the output port 76o and the drain port 76r is increased. Becomes a communication state, and the hydraulic oil is returned to the hydraulic pressure source 18 side. Conversely, if the vibration input is in the direction that the suspension stroke extends, the feedback chamber
Pressure F _L becomes lower than the pressure in the pilot chamber F _U, the spool 79 moves downward, between the supply port 76i and output port 76o is the communicating state, hydraulic oil is supplied from the hydraulic source 18 side . That is, the hydraulic oil can be circulated by the slight movement of these spools 79, and the pressure fluctuation up to a predetermined limit can be 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 designed to be printed. 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 microcomputer calculates the command values I, ..., I corresponding to the detection signal for suppressing / damping the posture variation separately within the range of I _{MIN to} I _MAX (see Fig. 4). Along with the drive circuit, pressure control valves 26FL-26
Command values I, ..., I are given to the proportional solenoid 77 of RR.

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 control signal CS is turned off when any of the actual current values I'in the above is a value (I _MIN <I '<0) that cannot be taken in the normal attitude control state, and turned on otherwise. Has become.

Here, the abnormal state detector 34 and the second controller 36
Constitutes an abnormal condition judging means.

The first and second controllers 32 and 36 described above 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 _MIN to the maximum value I _MAX are detected and output to the second controller 36. For this reason, since the second controller 36 turns on the switching control signal CS as described above, the exciting coil 67 of the electromagnetic solenoid 67 of the failsafe valve 22 is in the excited state. Therefore, the actuator 68 is attracted to the left end side in FIG. 2, the spool 59 also moves to the left end side, and takes the spool position (normal spool position) in FIG. 5 (a). That is, in this normal state, the first and second ports
T ₁ and T ₂ communicate with each other through the groove 62, and the third and fourth
Ports T ₃ and T ₄ of the supply side pipeline 48a and the bypass pipeline 48B communicate with each other.

Therefore, the line pressure from the hydraulic pressure source 18 is
Since it is supplied to the load side via the fail-safe valve 22,
The operate check valve 52 is open, and the return side also communicates with the tank 40 with the throttle 54 bypassed. In other words, each accumulator 24 accumulates pressure and the line pressure corresponding to P _MAX is the supply port of each pressure control valve 26FL-26RR.
It is supplied to the 76i and is in a state where the attitude 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 valve 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 79 of the pressure control valves 26FL to 26RR is finely moved in the axial direction to transfer the hydraulic oil to the hydraulic power source 18 side. 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 79 of the pressure control valves 26FL to 26RR, the vehicle body also tries to rock. Since the change in the state quantity (acceleration or the like) related to the swing is detected by the vehicle behavior detector 30, the first controller 32 suppresses the swing of the vehicle body as described above.
The command value I to be attenuated is supplied to each of the pressure control valves 26FL to 26RR. For this reason, 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, so that the hydraulic cylinders 28FL to 28RR are capable of suppressing or attenuating rolls, pitches, bounces, or the like. As a result, the vehicle body can be positively held in a flat posture, and thus a good riding comfort can be maintained.

The back pressure generated on the return side of each pressure control valve 26FL to 26RR in this attitude control is absorbed by the accumulators 70, 70.

During traveling in such a normal state, for example, one of the harnesses routed from the first controller 32 to each of the pressure control valves 26FL to 26RR in the vehicle body is dropped or disconnected due to long-term vibration or the like. And

As a result, when the actual current value I'in the corresponding pressure control valve 26FL (to 26RR) suddenly drops below I _MIN , this sudden drop is immediately detected by the abnormal state detector 34, and the second controller 36 as described above. It is determined that an abnormal state has occurred, and the switching control signal CS is switched from the previous ON to OFF. Therefore, the exciting coil 67 is changed from the excited state to the non-excited state, and the attraction force to the operator 68 is released, so that the spring force of the return spring 69 causes the operator to move.
68 is pushed to the right end side in FIG. 2, and the actuator 68 moves to a position where it comes into contact with the end face of the valve housing 58 (see FIG. 5 (d)).

Microscopically observing this movement process, there is a connection state represented by FIGS. 5B and 5C before reaching the state of FIG. 5D.

That is, as the spool 59 moves, first, the second convex portion 64 of the spool 59 closes the third port T ₃ and the inner peripheral surface of the valve housing 58 has the opening 61 as shown in FIG. By maintaining the blockage, the state in which the third port T ₃ and the fourth port T ₄ are blocked and the communication state between the first port T ₁ and the second port T ₂ is maintained.
In this state, the supply-side conduit 48s is still in the communication state, but the bypass conduit 48B is blocked, so that the throttle 54 is forcibly inserted into the return-side conduit 48r. Therefore, first, the rapid return of the hydraulic oil is hindered.

This is the length b between the first port T ₁ and the third port T ₃ ,
This is because there is the above-described relationship of a> b between the length a between the first convex portion 63 and the second convex portion 64, and at least the first, third, and fourth ports T ₁ , T _It is possible to reliably prevent the situation where ₃ and T ₄ are in the communication state at the same time and the high-pressure hydraulic oil on the accumulator 24 side escapes to the tank 40 via the operation check valve 52.

Further, as the spool 59 moves, the first convex portion 63 of the spool 59 faces the first port T ₁ while maintaining the closed state of the third port T ₃ as shown in FIG. And a gap communicating with the first port T ₁ is formed on both sides thereof. This is the axial length c of the first protrusion 63 and the first
This is because the diameter d of the port T ₁ has the above-described relationship of d> c. Therefore, the first and second ports T ₁ and T ₂ communicate with each other through the groove portion 62, and the first and fourth ports T ₁ and T ₄ communicate with each other through the opening portion 61 and the hollow portion 59A. These three ports are in communication at the same time. That is, the cutoff state of the bypass pipeline 48B and the communication state of the supply side pipeline 48s are maintained, and the supply pipeline 48s is upstream of the throttle 54 of the return pipeline 48r via one of the bypass pipelines 48B. Connected to the side. This allows the fail-safe valve 22 and the pressure control valves 26FL-26RR.
A portion of the hydraulic oil from the fluid pressure source 18 is added to the high-pressure hydraulic oil that has accumulated in the pipeline 48s and the accumulator 24 between and flows into the return-side pipeline 48r, and the pressure control valves 26FL to 26RR Back pressure suddenly rises to near the supply pressure.

Therefore, the actual current value I'in the pressure control valve 26FL (to 26RR) suddenly becomes zero, and the pilot pressure of the pressure control valve 26FL (to 26RR) related to the failure suddenly drops to zero. the chamber F _U, by the spool 79 out of balance of F _L is moved, the corresponding hydraulic cylinder 28FL (~
28RR) operating pressure tries to return via the pressure control valve 26FL (~ 26RR), but this hydraulic oil return is temporarily blocked,
It will be contained.

Further, as the spool 59 moves, FIG. 5 (d)
The spool position shown in is reached. That is, the second and third ports T ₂ , T ₃ are individually closed, and the first, fourth port T ₁ ,
T ₄ between each other becomes a communicating state, the supply-side pipe 48s, a bypass line 48B is cut-off state, and, ready for the load side of the fail-safe valve 22 are connected to each other, the switching operation is completed.

As a result, the rise of the back pressure that has risen as described above is eliminated, so that the enclosed pressure in the load-side path of the fail-safe valve 22 and the throttle 54 is made uniform while gradually decreasing through the throttle. Then, when the operating pressure, that is, the pilot pressure P _{P of the} operate check valve 52 decreases to the neutral pressure P _N , the operate check valve 52 is closed, so that the check valve 50 and the operate check valve 52 operate on the load side. The pressure is contained at neutral pressure P _N , and the sealed state is maintained for a long time.

Thus, even if the current value I ′ suddenly changes to zero due to the occurrence of the failure, the corresponding cylinder pressure is temporarily maintained at the value immediately before the occurrence of the abnormality, and then gradually adjusted to the neutral pressure P _N. . At this time, since the operating pressure on the load side is once confined by the back pressure and made uniform while adjusting to the neutral pressure P _N , the pilot pressure P _P is a value that more accurately reflects the enclosed pressure state. By this, highly accurate encapsulation is performed. In other words, it is possible to reliably prevent the situation where the high working pressure is released first and the pressure after filling is actually less than P _N. In particular, in this embodiment, since the line pressure is temporarily supplied from the hydraulic pressure source 18 and the back pressure is started up with good responsiveness, it is possible to reliably contain the operating pressure immediately before the occurrence of the abnormality. ing.

Therefore, even if an abnormality occurs, the vehicle body posture is not suddenly changed, and the vehicle can travel thereafter. In particular, even when the above-mentioned 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, resulting in a significant posture error. You can surely avoid the situation where it becomes stable and difficult to operate,
It does not give unnecessary unease to the occupants. This fail-safe effect is particularly effective because the harness for transmitting the command value I is laid around for a long time.

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 power supply is stopped, the posture control and the control of the fail-safe valve 22 are stopped, and at the same time, the rotation of the hydraulic pump 42 is stopped. By this, if it was in the normal state before the stop,
Operate check valve 52 as pilot pressure P _P decreases
Is closed, the load side is confined to the neutral pressure P _N , a flat posture with a constant vehicle height is secured, and if there is an abnormal state before the stop, the load side continues to the neutral pressure P _N. Contain it.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. Here, the same reference numerals are used for the same configurations as those of the first embodiment.

In the second embodiment, the shape of the first convex portion 63 of the spool 59 of the failsafe valve 22 is changed as shown in FIG. Specifically, the axial length c of the first convex portion is set with respect to the diameter d of the first port T ₁ of the valve housing 58.
Unlike the first embodiment, c> d. However, the condition of the axial length b between the _first and third ports T ₁ and T ₃ of the valve housing 58 with respect to the axial length a between the first and second convex portions 63 and 64 of the spool 59, a > B is observed as in the first embodiment.

 Other configurations are similar to those of the first embodiment.

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

First, during the attitude control in the normal state, the spool 59 takes the spool position shown in FIG. 9A, and the second and first ports T ₂ ,
The T _1's are in communication with each other through the groove 62, and the fourth and third
The ports T ₄ and T ₃ are in communication with each other through the side portion of the second convex portion 64. As a result, the supply side and the return side are in communication with each other.

If an abnormality occurs in the command value system from this state, the spool 59 is moved in the order represented by (b) to (d) in the same manner as described above.

That is, as shown in FIG. (B), the first to the fourth by the second convex portion 64 of the spool 59 tip, between the third port T _4, T ₃ is cut off, and, second, the first port T ₂ , T ₁ reaches the connection state that maintains the communication state. After that, as shown in FIG. 7C, the shutoff state between the _fourth and third ports T ₄ and T ₃ is maintained, and the shutoff between the second and first ports T ₂ and T ₁ is also shut off. The connection status arrives. And finally, as shown in FIG.
Maintaining the cutoff state between the third port T _4, T _3, the second port T ₂
It is possible to obtain a connection state in which the blockage is maintained and the first and fourth ports T ₁ and T ₄ communicate with each other.

That is, in the connection process described above, the bypass 48B is always shut off first ((b) in the same figure), and then the pipeline 48s on the supply side is shut off ((c) in the same figure) and the interconnection on the load side ( The same figure (d) is performed. Therefore, before the return side is shut off, the return side and the accumulator 24 side are in a connected state (that is, the first, third, and fourth ports T ₁ , T ₃ , T ₄ ports are in simultaneous communication), and the accumulator 24 side It is possible to reliably avoid the situation where high-pressure hydraulic oil escapes to the hydraulic power source 18 side via the bypass pipe 48B. Then, after preventing the hydraulic oil from escaping, the high-pressure hydraulic oil on the accumulator 24 side is turned to the drain port side of the pressure control valves 26FL to 26RR, whereby the back pressure can be quickly raised to near the supply pressure. . As described above, in this embodiment, unlike the first embodiment, since the assistance of the supply pressure of the hydraulic pressure source 18 is not obtained when the back pressure is raised, the response is slightly reduced, but the high pressure on the accumulator 24 side is reduced. Since it can be reliably forwarded, this also ensures containment of the operating pressure and prevents sudden changes in posture.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. Here, the same reference numerals are used for the same configurations as those of the first embodiment.

In the first embodiment, the fail-safe valve 22 is of the direct acting type, but in the second embodiment, as shown in FIG. 7 (a), the rotary fail-safe valve 22 is used. That is, in FIG. 1A, 93 is a hollow cylindrical valve housing, and 94 is a rotating body (moving body) having a substantially fan-shaped cross-section that is rotatable by sliding in the hollow portion 93A of the valve housing 93. ). As shown in the drawing, the valve housing 93 is provided with first to fourth ports T _{1 to} T ₄ corresponding to the above-described embodiment in a clockwise direction, and the rotating body 94 is opposed to the ports T _{1 to} T ₄ . Possible first protrusion
The groove 95, the groove 96, and the second protrusion 97 are sequentially formed in the same manner as in the first embodiment, and their positional relationships are also a> b, d> c. Here, a is the distance on the outer peripheral surface between the first and second convex portions 95 and 97, b is the distance on the inner peripheral surface between the _first and third ports T ₁ and T ₃ , and c
Is the outer peripheral distance of the first convex portion 95, and d is the inner peripheral side distance of the first port T ₁ .

Further, a drive unit for rotating the rotating body 94 within a predetermined range is provided on one side of the rotating body 94 in the axial direction by turning the switching control signal CS on and off. Reference numeral 98 is a flow path, and 99 is a stopper.

 Other configurations are the same as those in the first embodiment.

Therefore, in the normal control state, the rotating body 94 takes the rotating position shown in FIG. 7 (a), and when an abnormality occurs, it takes the positions shown in FIG. 7 (b) to FIG. These turning positions correspond to the spool positions shown in FIGS. 5 (a) to 5 (d), respectively, so that the same effect as that of the first embodiment can be obtained.

By the way, in the third embodiment, the first of the rotating body 94
The dimension c of the convex portion 95 may be c> d as in the second embodiment.

In each of the above-described embodiments, the hydraulic cylinders 28FL to 28RR for all the wheels are set to the neutral pressure state at once when an abnormality occurs, but the present invention is not necessarily limited to this, and may be changed as necessary. For example, the front wheel side and the rear wheel side may be individually controlled to the neutral pressure state.

Further, in the present invention, as the configuration for detecting the occurrence of the 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. The same effect can be obtained.

Further, in each of the above-described embodiments, the operating pressure is forcibly set to the neutral value P _N at the time of abnormality, but this is the posture in the most safe posture when the posture control of the vehicle body is lost, that is,
Since there is a margin in the suspension stroke and the purpose is to ensure a minimum vehicle height, it is not necessary to limit the neutral pressure, and a value in the vicinity thereof may be used.

Furthermore, the present invention may be configured such that an air pressure cylinder is mounted as the fluid pressure cylinder.

〔The invention's effect〕

As described above, in the active suspension according to the present invention, when an abnormality occurs in the power supply or the harness that gives the command value relating to the attitude control, the cylinder pressure is immediately maintained at the preset pressure, the abnormal state determination means, the fail safe. A failsafe mechanism including a valve and pressure holding means (check valve, open / close valve) is provided, and the valve housing and spool of the failsafe valve are provided at least on the supply side of the failsafe valve on the load side and on the return path and on the downstream side. The shape that can cut off the supply path and the return path (bypass path) and connect the downstream side of the supply path and the upstream side of the return path, that is, the load side to each other Since the throttle is provided in the return passage, the hydraulic oil accumulated on the load side of the supply passage is released to the fluid pressure source. And without make a back pressure by forwarding the return side of the reliable control valve. For this reason, the value of the cylinder pressure immediately before the occurrence of the abnormality can be reliably held, and thereafter, the value can be gradually adjusted to the set pressure and contained, thereby preventing a situation where the body posture suddenly changes when the abnormality occurs. In addition, the fail-safe effect that the suboptimal posture in which the vehicle can run is ensured thereafter can be obtained.

Particularly, in the suspension described in claim (2), the fail-safe valve switching procedure includes a connection state in which the upstream side of the supply path, that is, the fluid pressure source side and the upstream side (load side) of the return path communicate with each other. Since the supply pressure of the fluid pressure source also wraps around to the return side, the back pressure rises responsively and reliably to near the supply pressure, the working pressure is more reliably contained, and it is reliable for preventing sudden changes in the vehicle body posture. This has the effect of significantly improving the sex.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention, and FIG.
1 is a partial cross-sectional view showing the structure of the fail-safe valve in FIG. 1, FIG. 3 is a schematic cross-sectional view showing the structure of the pressure control valve in FIG. 1, and FIG. 4 is an output for the command value of the pressure control valve. Graphs showing pressure characteristics, FIGS. 5 (a) to 5 (d) are explanatory views showing the switching operation of the fail-safe valve of the first embodiment, and FIGS. 6 (a) to 6 (d) are respectively diagrams of the present invention. Explanatory drawing showing the switching operation of the fail-safe valve in the second embodiment, FIG. 7 (a)
(D) is an explanatory view showing switching operation of the fail-safe valve in the third embodiment of the present invention. 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 power source (fluid pressure source), 22 is a fail-safe valve, 26FL to 26RR are pressure control valves (control valves), 28FL ~
28RR is a hydraulic cylinder (fluid pressure cylinder), 30 is a vehicle behavior detector, 32 and 36 are first and second controllers, 34 is an abnormal state detector, 48s is a supply side pipeline, 48r is a drain side pipeline, 48B
Is a bypass line, 50 is a check valve, 52 is an operating check valve (open / close valve), 57 is a solenoid (driving part), 58 is a valve housing, 59 is a spool (moving body), 59A is a hollow part, 6
1 is an opening, 62 is a groove (recess), 63 and 64 are first and second protrusions,
93 is a valve housing, 94 is a rotating body (moving body), and 95 and 97 are first
1, the second convex portion 96 is groove (depression), 98 flow paths, T ₁ through T ₄ are first to fourth ports.

Claims (2)

(57) [Claims] 1. A fluid pressure cylinder provided between a vehicle body and a wheel, and a working fluid pressure from a fluid pressure source supplied to the fluid pressure cylinder via a supply passage and a return passage, In an active suspension including a control valve that controls according to a command value that corrects a posture change, a check valve installed in the supply path and a check valve installed in the return path and located downstream of the check valve. An on-off valve that closes when the supply pressure is less than or equal to a predetermined value, a throttle interposed upstream of this on-off valve, an abnormal state determination means that determines an abnormal state of the suspension, the supply path and the return. It is inserted in a bypass passage that bypasses the throttle of the passage, and when the abnormal state determination means determines a normal state, it connects the supply passage and the bypass passage, respectively, and when an abnormal state is determined, the supply path is bypassed. A fail-safe valve that blocks the supply passage and the bypass passage, respectively, and connects the downstream side of the supply passage and the upstream side of the bypass passage to each other, wherein the fail-safe valve includes the downstream side, the upstream side, and the side of the supply passage. A valve housing in which first to third ports communicating with the downstream side of the bypass passage are formed in this order, and a fourth port communicating with the upstream side of the bypass passage is formed;
The moving body slidably inserted into the insertion hole in the valve housing and the moving body is moved in the direction in which the third port is closed when the abnormal state is determined by the abnormal state determining means. An active suspension having a driving part, wherein a length of the moving body in a moving direction is formed to be larger than a length in a moving direction including a port diameter between the first and third ports. 2. The moving body comprises first and second convex portions formed on outer peripheral surfaces facing the first and second ports, respectively, and the first convex portion formed between the both convex portions. And a flow path that is open at one of the first convex portions at an adjacent position on the opposite side of the concave portion and that communicates with the fourth port. The active suspension according to claim 1, wherein the directional length is formed smaller than the diameter of the first port.