JPH01278818A - Active suspension - Google Patents

Abstract

PURPOSE:To prevent an abrupt change in vehicle height and instability of control by setting the fluid pressure of a fluid pressure cylinder to a neutral pressure upon occurrence of an abnormality in an electric instruction transmitting system for a control valve, and by setting the rate of pressure rise to a moderate value upon a pressure rise up to the neutral pressure. CONSTITUTION:When breakage of a signal wire from a control section 30 or the like occurs, pressure fed to hydraulic cylinders 26FL through 26RR is cut off so that pressure accumulated in an accumulator 20 is returned to a tank 40 through a three port selector valve 46 and an operation check valve 47. Accordingly, the pressure on the hydraulic feed side drops to a neutral pressure which is a set pressure of the operation check valve 47. As a result, the operation check valve 47 is closed so that the hydraulic cylinders 26RL through 26RR are held at the neutral pressure. At this time, since the pressure of a pressure chamber L in each hydraulic cylinder is lower than the neutral pressure, the pressure is raised up to the neutral pressure at a rate which is more moderate than that of pressure control sections 22FL through 22RR. Thus, it is possible to prevent an abrupt change in vehicle height and instability of control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fluid pressure cylinder inserted individually between a vehicle body and each wheel, and to each of the fluid pressure cylinders.

A pressure control valve that controls the working fluid pressure from a fluid pressure source according to a predetermined command value, and when an abnormality such as a disconnection or power down occurs in the electrical system that transmits the command value, the The present invention relates to an active suspension that has a fail-safe function that can accurately deal with problems.

[Prior Art] As an active type suspension, for example, there is one described in Japanese Patent Application Laid-Open No. 62-295714, which was previously proposed by the present applicant.

This conventional device includes a fluid pressure cylinder inserted between a vehicle body side member and each wheel side member, and a pressure control valve that individually controls the operating pressure of this fluid pressure cylinder according to a predetermined command value. It has an acceleration detection means for detecting the lateral acceleration or longitudinal acceleration of the vehicle body, and a control means for outputting a command value according to the detected value from the acceleration detection means to each pressure control valve. This is an attempt to actively suppress changes in posture in the front-back direction.

[Problem to be solved by the invention]

In the active suspension described above, each pressure control valve is individually provided for each of the four wheels, so the signal line that supplies the command value is long and routed in a complicated manner inside the vehicle body. As a result, there is a very high probability that the wire connections will loosen due to vibration or the like, or that the wires will break due to intermittent contact with other components over a long period of time. however,
The device described above is not designed to take into account abnormalities such as wire breakage, so if such an abnormality occurs, for example, while turning, the command value for the pressure control valve on the outer ring side suddenly changes to zero. This causes an unresolved problem in that the hydraulic cylinder on the outer wheel side suddenly drops to its lowest stroke, which causes a significant sudden change in vehicle height and unstable steering.

Therefore, this invention was made with a focus on such unresolved problems, and when an abnormality is detected in the electrical system that transmits the command value to the pressure control valve, the working fluid pressure of each fluid pressure cylinder is is set to a neutral pressure corresponding to the neutral state of the fluid pressure cylinder, and in this case, at least, when the working fluid pressure of the fluid pressure cylinder is raised from a state below the neutral pressure to the neutral pressure, the pressure increase rate is slowed. The purpose is to solve the unresolved problems mentioned above.

[Means to solve the problem]

In order to achieve the above object, as shown in FIG. A pilot pressure type pressure control valve equipped to correspond to the
An active type equipped with a fluid pressure cylinder that operates based on the output pressure of each pressure control valve and is individually inserted between the vehicle body and wheels, and changes the command value in response to changes in the vehicle attitude. In the suspension, an abnormality detection means detects an abnormality in the electrical system that provides a command value to each of the pressure control valves, and when the abnormality detection means detects an abnormality in the electrical system, the supply pressure of working fluid to each of the pressure control valves is determined. , neutral pressure setting means for setting the return pressure to a neutral pressure corresponding to the neutral state of the fluid pressure cylinder; and a pilot pressure supply path for each of the pressure control valves when the abnormality detection means detects an abnormality in the electrical system. pilot pressure supply path blocking means for blocking the pilot pressure supply path, and permitting flow of hydraulic fluid from the return side upstream to the downstream side of the return side path of each of the pressure control valves to the fluid pressure source; A flow direction control means is inserted to prevent hydraulic oil from flowing from the to the upstream side.

[Effect]

In this invention, an abnormality in the electrical system that provides command values to each pressure control valve is detected by the abnormality detection means. When this abnormality is detected, the neutral pressure setting means sets the supply pressure and return pressure of working fluid from the fluid pressure source to each pressure control valve to the neutral pressure, and the pilot pressure supply path blocking means sets each pressure control valve to the neutral pressure. The pilot pressure supply path of the pressure control valve is cut off, the pilot pressure drops, and each fluid pressure cylinder and the return side of each pressure control valve are communicated with each other. Therefore, when the working pressure of the fluid pressure cylinder is higher than the neutral pressure, the hydraulic oil flows to the fluid pressure source via the flow direction control means, and when the working pressure of the fluid pressure cylinder is lower than the neutral pressure, the flow direction control means causes the hydraulic oil to flow to the fluid pressure source. Flow is blocked and neutral pressure is gradually reached due to leakage of hydraulic fluid from the supply side of the pressure control valve.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 2 to 8. This example shows a case in which the present invention is applied to an active suspension that controls the lateral attitude of a vehicle.

In FIG. 2, 10FL to 10RR indicate the front seat to the rear right wheel, 12 indicates a wheel side member (suspension arm) connected to each wheel 10FL to 10RR, and 14 indicates 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 power source 18 as a fluid pressure source, an oil passage opening/closing mechanism 19 installed on the downstream side of this hydraulic pressure source 18, and a front wheel side on the downstream side of this oil passage opening/closing mechanism 19.
Accumulator 2 for accumulating pressure installed corresponding to the rear wheel side
0.20, pressure control units 22FL to 22RR installed downstream of the accumulator 20.20 and corresponding to the wheels 10FL to 10RR, respectively, and between the vehicle body side member 14 and each wheel side member 12. Individually installed pressure control section 2
Hydraulic cylinders 26FL to 26 as fluid pressure cylinders whose working oil pressure is controlled by the output pressure of 2FL to 22RR
1? R, a lateral acceleration sensor 28 for detecting lateral acceleration acting in the left-right direction of the vehicle body, and a lateral acceleration sensor 28 that controls the output pressures of the pressure control units 22FL to 22RR based on the lateral acceleration detection signal, and the oil passage opening/closing mechanism 19. It has a controller 30 that controls the. In addition, the hydraulic cylinder 26FL~2
Each of the pressure chambers of the 6RR, which will be described later, is communicated with an accumulator 34 for vibration absorption via a throttle valve 32.

Furthermore, hydraulic cylinders 26FL to 261? I? A coil spring 36, which has a relatively low spring constant and supports the static load of the vehicle body, is disposed between the vehicle body side and the wheel side of each of the coil springs 36.

The hydraulic power source 18 includes a reservoir tank 4 that stores hydraulic oil.
0, and the hydraulic oil feeding side of the reservoir tank 40 includes at least a hydraulic pump 42 whose rotational drive source is the engine of the vehicle, and a check valve 44 disposed on the discharge side of the pump 42. , and a predetermined pressure (here, 100 (kgf/cm")) inserted between the discharge side of the hydraulic pump 42 and the return side to the reservoir tank 40 (7)
It is configured with a relief valve 45.

The oil passage opening/closing mechanism 19 includes a solenoid-operated three-boat switching valve 46 inserted between the check valve 44 and the accumulator 20, 20, and a hydraulic oil return flow path of the hydraulic power source 18. It is configured with an operating check valve (pilot operated check valve) 47. 3 boat switching valve 4
6, when the excitation current I from the controller 30 is supplied to the excitation coil, the rP and AJ ports communicate, the rA and RJ ports are disconnected, and on the contrary, the excitation current IK is not supplied. If not, the rP and AJ ports are cut off, and the rA and Rj ports are communicated.

In addition, the operation check valve 47 is a three-boat switching valve 4.
The valve is opened when the output pressure of the hydraulic power source 18 on the downstream side of 6 is equal to or lower than the set value (here, neutral pressure: 50 (kgf/cm")) and is equal to or lower than the set value. When the valve is closed.

Therefore, when the vehicle is stopped and the engine is not rotating, the operating check valve 47 maintains the hydraulic path downstream of the hydraulic power source 18 at neutral pressure.

In addition, the engine is rotating steadily, and the 3-boat switching valve 4
In a steady state where the rP-AJ boats 6 are in communication, line pressure determined by the relief valve 45 is supplied from the hydraulic power source 8 to the hydraulic system.

Further, each of the pressure control units 22FL to 22RH has a third
As shown in the figure, a pilot pressure operated pressure control valve 49
FL (~49RR) and this pressure control valve 49FL (~4
9RR), a cut valve 50FL (~50RR) that shuts off the pilot pressure passage, which will be described later, and a pressure control valve 49PL (~50RR), which will be described later.
49RR) and a check valve 51FL (~51R1i) inserted on the return side to the hydraulic power source 8 are integrally formed.

Among these, the pressure control valve 49FL (~49RR) has a cylindrical valve housing 52 and a proportional solenoid 53 integrally provided therewith. And valve housing 5
2, an upper insertion hole 52U in FIG. 3 and a lower insertion hole 52L in the same figure are coaxially formed by a dividing plate 52A having a communication hole 52a of a predetermined diameter. Further, a fixed throttle 54 is provided at the upper part of the insertion hole 52L and at a lower position separated from the defining plate 52A by a predetermined distance. is formed.

Moreover, below the fixed throttle 54 in the insertion hole 52L,
A main spool 58 is disposed so as to be slidable in its axial direction. Spring chambers Fu, Ft are formed at the upper and lower ends of the main spool 58 in the axial direction, and the upper and lower ends of the main spool 58 are formed by offset springs 60A, 60B disposed in the spring chambers F, FL, respectively. The offset position is regulated. Then, an input port 52i, an input/output boat 52n, and an output boat 52o are formed in this order from the lower side at a position facing the lower side of the fixed throttle 54 in the insertion hole 52L, and among these, the input port 521 is connected to hydraulic piping. The output boat 520 is connected to the hydraulic oil supply side of the oil passage opening/closing mechanism 19 via the hydraulic piping, and the output boat 520 is connected to the drain side of the oil passage opening/closing mechanism 19 via the hydraulic piping. It is connected to the pressure chamber of the hydraulic cylinder 26FL (~26RR).

The main spool 58 has a land 58a facing the input port 52i and a land 58 facing the output boat 52o.
b, an annular groove-shaped pressure chamber 58c formed between the two ends 58a and 58b, and a pilot passage 58d communicating the pressure chamber 58c and the lower spring chamber FL.

A poppet 68 is disposed in the upper insertion hole 52U so as to be slidable in the axial direction thereof, and the poppet 68 defines the insertion hole 52U into two groups in the axial direction, and the communication hole 52a The flow rate of hydraulic oil flowing through the pilot chamber PRI, that is, the pressure in the pilot chamber PRI can be adjusted.

Furthermore, the input port 52i is a pilot passage 52s.
communicates with the pilot room PRI via a
) 52o connects to the insertion hole 52U via the drain passage 52t.
is communicated with.

On the other hand, the proportional solenoid 53 includes a plunger 70 that is slidable in the axial direction and a poppet 68 of the plunger 70.
It has an actuator 70A fixed to the side and an excitation coil 72 that drives the plunger 70 in its axial direction. be done. As a result, the movement of the plunger 70 urges the poppet 68 via the actuator 70A, controls the position of the poppet 68, and controls the amount of oil passing through the communication hole 52a, that is, the pilot chamber PR.
It is possible to control the pilot pressure of I.

Here, the output pressure P (control pressure pc) of the hydraulic oil output from the input/output boat 52n of the pressure control valve 49 is proportional to the excitation current ■ applied to the excitation coil 72, as shown in FIG. controlled.

On the other hand, the cut valve 50FL (~50RR) is disposed in a part of the valve housing 52 of the pressure control valve 49FL (~49RR), as shown in FIG. 3.

That is, the insertion hole 74A is formed in the center of the valve body 74,
A plunger 76 is slidably disposed within the insertion hole 74A and has a plunger 5i biased by a spring 75 and an actuator 76A fixed to the other end. The tip of the actuator 76A is configured to block the pilot passage 52s when the plunger 76 moves downward in FIG. 3. Further, the valve body 74 is equipped with an excitation coil 77, and during normal operation, an excitation current I is supplied to the excitation coil 77 from the controller 30. Therefore, under normal conditions, the plunger 76 is urged upward in FIG. 3 against the pressing force of the spring 75, and the pilot passage 5
2s is open. However, in the event of an abnormality described later,
The excitation current I from the controller 30 is no longer supplied, the plunger 76 is urged by the pressing force of the spring 75 and moves downward, and the pilot passage 523 is cut off.

Further, the check valve 51FL (-51RR) is formed by using a part of the valve housing 52 as a valve body, and a poppet 79 is disposed to be slidable through an insertion hole 78 in the valve body. A spring 80 is attached to one end of the poppet 79.
is interposed, and the output flow path 52o is blocked by the pressing force of the spring 80. Therefore, when the return oil pressure exceeds the cranking pressure of the check valve 51FL (~511?R), the return side flow path is opened, but the reverse flow is prevented.

Further, each of the hydraulic cylinders 26FL to 26RR has a cylinder tube 26a, as shown in FIGS. 2 and 3, and a lower pressure chamber is formed in the cylinder tube 26a, which is separated by a piston 26C. There is. The lower end of the cylinder tube 26a is attached to the wheel side member 12, and the upper end of the piston rod 26b is attached to the vehicle body side member 14. In addition, each of the pressure chambers is
A pressure control valve 49FL (~49RR) is connected to the pressure control valve 49FL (~49RR) through a hydraulic piping, a part of which is provided in the axial direction inside the piston rod 26b.
The input/output port 52n is connected to the input/output port 52n.

On the other hand, the aforementioned lateral acceleration sensor 28 is disposed at a predetermined position in front of the center of gravity of the vehicle, and this lateral acceleration sensor 28 detects the lateral acceleration acting on the vehicle and generates an analog voltage signal proportional to the lateral acceleration. A lateral acceleration signal g7 is output to the controller 30.

Further, the controller 30, as shown in FIG.
An A/D converter 88 that converts the input analog lateral acceleration signal gv into a digital value, a control microcomputer 90, and a digital control signal SC1..., SC output from the microcomputer 90. D/A converters 92A to 92D converting the D/A converters 92A to 92D into analog quantities, and an excitation current I as a command value based on the outputs of the D/A converters 92A to 92D, to the pressure control valve 49F.
Excitation coil 72 from L to 49RR. ..., 72, and drive circuits 94A to 94D that output signals individually.

The controller 30 also includes drive circuits 94A to 94D.
Current detection circuits 95A to 95D that individually detect the values of the excitation currents output by the current detection circuits 95A to 95
A/D converters 96A to 96D that individually convert the outputs of D into digital quantities and supply them to the microcomputer 90;
A control signal SS is output from the microcomputer 90 to the three-boat switching valve 46 and the cut valve 50FL (~50RR).

It is equipped with interface circuits 97A and 97B that output SS.

Of these, the microcomputer 90 includes at least an interface circuit 98, an arithmetic processing unit 99, a RAM, an R
The storage device 100 includes a storage device 100 such as an OM. The arithmetic processing unit 99 reads the detected values of the lateral acceleration detection signal g7 and the excitation current (2) via the interface circuit 98, and performs calculations and other processing described later based on these.

The storage device 100 stores in advance a predetermined program, fixed data, etc. necessary for the execution of processing by the arithmetic processing unit 99.

In addition, as shown in FIG. 6, each of the drive circuits 94A to 94D has a comparator 102 at its input stage, and the comparison output is amplified to generate an exciting current in the exciting coil 72 of the pressure control valve 49FL (~49RR). , and a transistor 103 that supplies . Then, the emitter potential of the transistor 103 is detected, and this is compared with the output of the D/A converter 92A (~92D) in the comparator 102.

Furthermore, each of the current detection circuits 95A to 95D includes a transistor 10 on the output side of the drive circuit 94A (to 94D).
3 and outputs a corresponding detection signal to the microcomputer 90 via the A/D converter 96A (96D).

Next, the operation of the above embodiment will be explained.

First, processing operations by the controller 30 will be explained.

When the ignition switch of the vehicle is turned on, the controller 30 starts executing a predetermined main program, and during the execution, executes the timer interrupt process shown in FIG. 7.8 for a predetermined period of time (for example, 20 msec).
Execute each.

That is, in step (3) in FIG. 7, the arithmetic processing unit 99 of the microcomputer 90
The lateral acceleration signal g digitized by the A/D converter 88 is read in through the A/D converter 88, and the lateral acceleration G7 is set by referring to a storage table or the like based on the lateral acceleration signal g read in step (3).

Next, proceed to step ■, and multiply the lateral acceleration G7 set in step ■ by a predetermined gain constant by 7 to set the excitation current ■
, calculate the value of . At this time, the pressure control valve 4 on the left side of the vehicle
9FL, 49RL and right pressure control valve 22FR, 2
In 2RR, the value of the excitation current (2) is set so that the output pressures generate mutually opposite biasing forces.

Next, move to step ■ and calculate the excitation current calculated in step ■! A control signal SC corresponding to the value of is individually output to A/D converters 92A to 92D. The A/D converters 92A to 92D convert the control signal SC into an analog quantity and output it to the corresponding drive circuits 94A to 94D.
The pressure control valves 49FL to 49 correspond to the excitation current I calculated in step (3) from the drive circuits 94A to 94D.
The signals are individually output to the excitation coil 72 of the RR, and the process returns to the main program.

As a result, hydraulic oil having a pressure that resists changes in vehicle body roll is supplied from the input/output boat 52n to each of the pressure control valves 49FL to 49RR, and posture changes are suppressed.

On the other hand, in step (2) in FIG. 8, the arithmetic processing unit 99
The detection signal of the current detection circuit 95A (~95D) is read through the A/D converter 96A (~96D), and the drive circuit 9
The value of the actual excitation current I output from 4A (~94D) is calculated. Next, in step ■, the exciting current I,
Standard value ■ that is set in advance. Compare with. This reference value ■ゎ is set to a value (for example, 0.1 (A)) that can detect that the value of the excitation current ■ has decreased to a value that cannot be obtained by normal roll control, etc. ■
Based on the judgment of the controller 30, the pressure control unit 22
This is to check for disconnections in the harnesses, etc., which are wired to each of FL to 22RR and transmit the excitation current l.

Therefore, in step ■, I! +>1. If this is the case, it is assumed that the program is operating normally, and the program proceeds to step (2), where it commands the rP-AJ boat communication of the 3-port switching valve 46 and the opening of the pilot passages 52s of the cut valves 50PL to 50RR, and returns to the main program. On the other hand, ■, ≦■. In the case of , it is assumed that the command value is about to drop suddenly due to a disconnection, and the process moves to step (2), where the supply of control signals ss and ss is stopped, and the 3-port switching valve 46 and cut valve 50FL~
The excitation current for the 5ORR excitation coil becomes zero.

As a result, the 3-port switching valve 46 changes from opening port rP-AJ and blocking rA-RJ to boat rP-A.
Switches to J shutoff and rA-RJ open, and the oil passage on the hydraulic oil feed side is forcibly shut off.

In addition, for the cut valves 50FL to 50RR, the plunger 7
6 is biased by the spring 75, and the pilot passage 52S is blocked.

Next, the overall operation will be explained.

Assume that the device is now in a normal operating state without the aforementioned wire breakage or the like. When the ignition switch of the vehicle is turned on, processing by the controller 30 is started, and the discharge pressure of the hydraulic boat 42 gradually increases as the engine rotates. When this pressure exceeds the neutral pressure, hydraulic oil is supplied to the 3-port switching valve 46 (the valve is in the state where the boat rP-AJ is open as described above) via the check valve 44, and the operating check valve 47 is now open from closed. In this state, the relief valve 45 is
For example, 100 [kgf
7cm” line pressure is applied to pressure control valves 49FL to 49R.
is supplied to the input port of R. This pressure control valve 49FL
-4911R, the output pressure is set as described above in accordance with the value of the excitation current (2) applied at that time, and is individually supplied to the corresponding hydraulic cylinders 26FL-26RR.

Therefore, if we assume that the vehicle is currently traveling straight on a good road at a constant speed, there will be no lateral acceleration in this state, so
The lateral acceleration detection signal g of the lateral acceleration sensor 28 is its neutral value. Therefore, the excitation current I, set through the process shown in FIG.
They are output to pressure chambers 6FL to 26RR, respectively. As a result, the neutral pressure P in the hydraulic cylinders 26FL to 26RR,
A thrust corresponding to this is generated, and the space between the vehicle body side member 14 and the wheel side member 12 is adjusted to a predetermined neutral state.

Further, when the vehicle shifts from this constant speed running state to a right-turning state by turning the steering wheel, for example, by turning the steering wheel, a roll is generated that tilts downward to the left with a roll angle when viewed from the rear side of the vehicle body. At this time, a lateral acceleration signal g7 greater than the neutral value is detected from the lateral acceleration sensor 28, and the controller 3
0 is a value higher than the neutral excitation current ISN for the pressure control valves 49FL and 49RL on the left side of the vehicle, and a neutral excitation current rsN for the pressure control valves 49FR and 49RR on the right side of the vehicle through the process shown in FIG. each supplying a lower value.

For this reason, as mentioned above, the front left pressure control valve 49
The output pressure P of FL and 49RL becomes larger than the neutral pressure PM, and the corresponding hydraulic cylinders 26FL and 26
The pressure in the lower pressure chamber of RL increases from the neutral pressure P9.

For this reason, the hydraulic cylinder 26PL.

26RL generates a biasing force that resists the stroke contraction between the vehicle body and the wheels, thereby suppressing the vehicle body from sinking. On the other hand, the output pressure P output from the front and rear right pressure control valves 22PR and 22RR becomes a value smaller than the neutral pressure PM, and the pressure in the lower pressure chamber of the corresponding hydraulic cylinders 26FL and 26RL becomes the neutral pressure P. , becomes smaller. Therefore, although the strokes of the hydraulic cylinders 26FL and 26RL are about to extend, the biasing force against this is reduced, and the lifting of the vehicle body is not promoted.

On the other hand, in contrast to the above-mentioned right-turning state, in the left-turning state, the roll suppression control is performed accurately and the attitude is stabilized by the operation opposite to that described above.

In such a normal operating state, the pressure control valve 49FL is now connected from the drive circuits 94A to 94D of the controller 30.
Assume that any of the signal lines from 49RR to 49RR has fallen off or broken due to long-term vibration or the like. As a result, the excitation current I suddenly drops, but this sudden change causes the current detection circuit 95
Detected by any one of A to 95D, the controller 3
At 0, it is determined through the process shown in FIG. 8 that an abnormality has occurred. For this reason, the controller 30 immediately sets the three-boat switching valve 46 and the cut valve 50 in order to respond to this.
. . , the supply of the control signal SS that was being output to the terminal 50 is stopped (step ■ in FIG. 8).

Therefore, as described above, the hydraulic cylinders 26PL to 2
The supply pressure to the 6RR side is cut off, and the accumulator 20.2
0 pressure accumulation is 3 boat switching valve 46. The hydraulic oil is returned to the tank 40 via the operating check valve 47, and the pressure in the hydraulic system on the hydraulic oil sending side decreases.
7, the operating check valve 47 is switched from open to closed at the point when the pressure has decreased to the neutral pressure, which is the set pressure of 7.

Therefore, the hydraulic paths of the three-boat switching valve 46 and the operating check valve 47 on the side of the hydraulic cylinders 26FL to 26RR are sealed at neutral pressure.

At the same time, the pilot passages 52s of the pressure control valves 49FL to 49RR are blocked by the cut valves 50PL to 50RR, so the pressure in the pilot chamber PR1 decreases, the spool 58 moves, and the input/output boat 52n
and the output port 52o are in communication. Therefore, when the pressure in the pressure chamber of the hydraulic cylinder 26FL (~26RR) is higher than the neutral value, the hydraulic fluid is transferred to the pressure control valve 49FL (~4
9RR), the output port 52o, the check valve 5IFL (~51RR), and the operated check valve 47, and are returned to the tank 40 side. On the other hand, when the pressure in the pressure chamber is lower than the neutral value, the check 51FL (~51RR) prevents the hydraulic fluid from flowing back, and the pressure is temporarily maintained. Thereafter, the hydraulic pressure in the feed side pipe is introduced into the pressure chamber by leakage through the inlet capo) 52i and the inlet/output capo) 52n of the pressure control valve 49FL (~49RR), so that the hydraulic cylinder 2
The pressure of 6FL (~26RR) gradually becomes neutral pressure, and finally the four-wheeled vehicle body.

The stroke between the wheels is set to its neutral state.

Therefore, even if an abnormal condition occurs during turning, such as a break in any command value transmission path or a power failure of this device,
The outer ring side, whose working pressure is higher than the neutral pressure, becomes neutral relatively quickly, and the inner ring side, whose working pressure is lower than the neutral pressure, is gradually set to the neutral state.
Upthrust is avoided. Therefore, this fail-safe function not only prevents the worst situations such as rollover, but also suppresses sudden changes in vehicle height, prevents a decrease in steering stability, and reduces ride comfort and anxiety for the passengers. be excluded.

Furthermore, in this embodiment, when the -degree failsafe function is activated, the neutral vehicle height can be maintained for a long period of time. Therefore, even if the above-mentioned abnormality occurs while driving, in most cases it will be possible to drive in a neutral state until the target value that allows the abnormality to be corrected. You can also avoid situations where you have to do this.

Here, in the wood brush embodiment, current detection circuits 95A to 95D
, A/D converters 96A to 96D and step ■ in FIG.
An abnormality detection means is formed by the processing of , (2), and the processing of step (2) in the same figure, the D/A converter 97A, and the oil passage opening/closing mechanism 1 are performed.
9 forms a neutral pressure setting means, and step
processing and D/A converter 97B1 power 7 valve 50FL~5
A pilot pressure supply path blocking means is formed by ORR.

In addition, in the above-mentioned embodiment, the hydraulic cylinders 26FL to 26RR for all wheels are finally brought into a neutral state when an abnormality occurs, but the present invention is not necessarily limited to this, and may be modified as necessary. For example, a configuration may be adopted in which the front wheels and the rear wheels are individually controlled to a neutral state.

Further, in the above-described embodiment, the signal for monitoring the excitation current I output from the drive circuits 94A to 94D of the controller 30 was used as a signal for detecting an abnormality, but this also monitors the power supply voltage of the controller 30, for example. A signal may be used to activate the fail-safe function described above in the event of a power failure.

Furthermore, the cut valve 50FL (~50RR) and the check valve 51FL (~51RR) are not only integrally molded with the pressure control valve 49FL (~49RR) as described above, but also are piped from the pressure control valve 49FL (~49RR). The hydraulic path is drawn out to the outside, and a cut valve 50FL (~50RR) and a cut valve 51FL (~50RR) are installed in this path.
51RR) may be inserted separately.

Furthermore, the present invention is applicable not only to active suspensions with roll suppression control as described above, but also with pitch suppression control,
The present invention can be similarly applied to bounce damping control and vehicle body change suppression control performed in combination, and the same effects can be obtained.

Furthermore, in each of the above-mentioned embodiments, a case was explained in which a hydraulic cylinder was used as the fluid pressure cylinder.
It may also be a pneumatic cylinder or the like.

〔Effect of the invention〕

As explained above, in the present invention, when an abnormality is detected in the electrical system that transmits a command value to the pressure control valve, the working fluid pressure of each fluid pressure cylinder is changed to the neutral pressure corresponding to the neutral state of the fluid pressure cylinder. In addition, in this case, at least when the working fluid pressure of the fluid pressure cylinder is raised from below the neutral pressure to the neutral pressure, the pressure increase speed is slow, so for example, when the pressure is being controlled while turning, Even if an abnormality occurs such as a break in the electrical system that transmits the command value to the valve or a power supply stoppage due to a power supply failure, the vehicle attitude is maintained in a neutral state while avoiding push-up from the inner wheels. This prevents significant sudden changes in vehicle height, thereby preventing deterioration of steering stability and ride comfort.

On the other hand, since the neutral vehicle height can be maintained for a long period of time, it is possible to continue driving in a position that does not pose a problem for practical use until the abnormality is repaired. As a result, an effect can be obtained in that an accurate fail-safe function against a failure in the command value system is exhibited.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram showing an overview of the present invention, FIG. 2 is a schematic configuration diagram showing an embodiment of the invention, FIG. 3 is a sectional view showing a schematic configuration of a pressure control section, and FIG. 4 is a pressure A graph showing the excitation current versus output pressure of the control valve, Fig. 5 is a block diagram showing the configuration of the controller, Fig. 6 is a block diagram showing the configuration for detecting an abnormality in the excitation current, and Fig. 7 is executed in the controller. FIG. 8 is a schematic flowchart showing the abnormality detection control executed in the controller. 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 source (fluid pressure source), 19
is the oil passage opening/closing mechanism, 22FL to 22RR are the pressure control parts, 2
6FL-26IIR are hydraulic cylinders, 30 are controllers, 49FL-49RR are pressure control valves, 50FL-50
RR is a cut valve, 51FL to 51RR are check valves, 9
0 is a microcomputer, 95A-94D is a drive circuit, 95A-95D is a current detection circuit, 96A-96D is A
/D converters 97A and 97B are interface circuits.

Claims (1)

[Claims] (1) a fluid pressure source that supplies hydraulic oil at a set pressure; a pilot pressure type pressure control valve that controls the pressure of the hydraulic oil according to a predetermined command value and is installed corresponding to each wheel;
An active type equipped with a fluid pressure cylinder that operates based on the output pressure of each pressure control valve and is individually inserted between the vehicle body and wheels, and changes the command value in response to changes in the vehicle attitude. In the suspension, an abnormality detection means detects an abnormality in an electrical system that provides a command value to each of the pressure control valves, and when the abnormality detection means detects an abnormality in the electrical system, the supply pressure of working fluid to each of the pressure control valves is determined. , neutral pressure setting means for setting the return pressure to a neutral pressure corresponding to the neutral state of the fluid pressure cylinder; and a pilot pressure supply path for each of the pressure control valves when the abnormality detection means detects an abnormality in the electrical system. a pilot pressure supply path blocking means for blocking the fluid pressure source; An active suspension characterized by interposing a flow direction control means for preventing the flow of hydraulic oil from the flow to the upstream side of the active suspension.