JPH02200512A - Suspension device for automobile - Google Patents

Abstract

PURPOSE:To estimate the shortage of operational liquid in an active suspension by making a judgement of malfunction when the period of time from the stopping to the starting of accumulation by an accumulation control means is not more than the predetermined. CONSTITUTION:A pressure valve 28 that is formed as an accumulation control means opens at a predetermined value of the pressure and closes at the predetermined, repeating a series of the processes. A period of time t1 from the opening and to the closing of the pressure valve 28, as well as a period of time t2 from the closing to the opening thereof are detected individually, and when the t1 is not more than a first predetermined value, and when the t2 is not less than a second predetermined value, it is judged as malfunction. Only when the judgement of malfunction is repeated 5 times, it is finally judged as the malfunction. When the judgement of the malfunction is made, active control is stopped and a control valve 26 for relief is opened, so as to actuate an alarm 27. Shortage of operational liquid can thus be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a suspension device for a vehicle.

(Prior art) Vehicle suspensions, generally called passive suspensions, have a damper unit consisting of a hydraulic shock absorber and a spring (generally a coil spring), and the suspension characteristics are determined by the preset characteristics of the damper unit. Set uniformly. Of course, it is also possible to make the damping force of the hydraulic shock absorber variable, but this does not significantly change the suspension characteristics.

On the other hand, recently, what is called an active suspension has been proposed in which the suspension characteristics can be changed arbitrarily. A cylinder device is installed between the cylinder device and the suspension characteristics are controlled by controlling the supply and discharge of hydraulic fluid to the cylinder device (see Japanese Patent Publication No. 14365/1983).

In this active suspension, by supplying and discharging hydraulic fluid from the outside, suspension characteristics can be significantly changed for various controls such as vehicle height control, roll control, and pitch control.

-For active suspensions as mentioned above,
Basically, a vehicle height sensor that detects the vehicle height is used for attitude control, but if this vehicle height sensor fails, problems will occur in suspension control.

For this reason, as shown in Japanese Patent Application Laid-Open No. 62-289417, a system has been proposed that determines whether the vehicle height sensor is normal or abnormal by looking at the rate of change of the output value of the vehicle height sensor. Furthermore, as shown in Japanese Patent Application Laid-Open No. 61-282110, when the output values of some vehicle height sensors do not change even though the output values of a plurality of vehicle height sensors are changing,
A system has also been proposed in which it is determined that some of the vehicle height sensors are malfunctioning.

(Problems to be Solved by the Invention) - In the active suspension vehicle mentioned above, an accumulator is used in the hydraulic fluid supply/discharge circuit to store high-pressure hydraulic fluid. It will be done. That is, it is common to ensure a stable supply of hydraulic fluid by pumping high-pressure hydraulic fluid from a reservoir tank into an accumulator. Then, the pressure in the accumulator is adjusted by a pressure accumulation control means such as an unload valve so that it is within a range between a predetermined lower limit value and a predetermined north limit value.

Incidentally, although it is necessary to avoid insufficient pressure in the accumulator as much as possible when performing active control, it is conceivable that the pressure in the accumulator may drop abnormally due to some cause such as pipe leakage.

In this case, before the pressure on the accumulator side drops abnormally due to piping leaks, etc., it is possible to know in advance the situation where such an abnormality will occur, that is, the situation where there will be a shortage of hydraulic fluid. It's convenient.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a suspension system for a vehicle in which a situation that may cause a shortage of hydraulic fluid can be known in advance in an active suspension vehicle.

(Operation of Means 1 for Solving the Problems) In order to achieve the above-mentioned object, the first configuration of the present invention is as follows.

In other words, there is a cylinder device installed between the sprung weight and the unsprung weight that changes the vehicle height according to the supply and discharge of hydraulic fluid, and a cylinder device that pumps up the hydraulic fluid in the reservoir to supply high-pressure hydraulic fluid. and a pump as a pressure source that discharges.

The discharge pressure from the pump is stored in an accumulator (when the pressure in the accumulator reaches a predetermined lower limit, high-pressure hydraulic fluid is stored in the accumulator, and the pressure is increased to a predetermined upper limit that is greater than the lower limit). pressure accumulation control means for stopping the pressure accumulation in the accumulator when the pressure reaches the specified value;

a supply control valve for supplying the hydraulic fluid pressure accumulated in the accumulator to the cylinder device; a discharge control valve for releasing the hydraulic fluid from the cylinder device to the reservoir tank; supply and discharge control means for controlling the supply and discharge of hydraulic fluid to and from the cylinder device by controlling the supply and discharge control valve according to conditions; A failure determining means for determining that a failure occurs at a certain time;

Moreover, in order to achieve the above-mentioned object, in the present invention,
The second configuration is as follows. In other words, there is a cylinder device installed between the seven springs and the unsprung weight that changes the vehicle height according to the supply and discharge of hydraulic fluid, and a cylinder device that pumps up the hydraulic fluid in the reservoir tank and discharges high-pressure hydraulic fluid. A pump as a pressure generation source; an accumulator that stores discharge pressure from the pump; and when the pressure of the accumulator reaches a predetermined lower limit, high-pressure hydraulic fluid is stored in the accumulator, and when the pressure of the accumulator reaches a predetermined lower limit, pressure accumulation control means that stops accumulating pressure in the accumulator when a predetermined upper limit value greater than the above value is reached; a supply control valve that supplies the hydraulic fluid accumulated in the accumulator to the cylinder device; a discharge control valve for releasing hydraulic fluid from the cylinder device to the reservoir tank;

supply and discharge control means that controls the supply and discharge of hydraulic fluid to and from the cylinder device by controlling the supply and discharge control valve according to predetermined conditions; and a time period from the start of pressure accumulation to the stop of pressure accumulation by the pressure accumulation control means. 5. A failure determination means that determines that a failure has occurred if a predetermined time has elapsed.

The first configuration and the second configuration are illustrated in a block diagram as follows.
This is shown in Figure 0.

1. In the event of a failure where hydraulic fluid leaks.

For example, if there is a pipe leak, a supply control valve is stuck open, or a cylinder device leaks, the consumption of hydraulic fluid increases by the amount of the leak. and,
At the time of such a failure, the time from the stop of pressure accumulation to the start of pressure accumulation by the pressure accumulation control means is shorter than during normal times, while the time from the start of pressure accumulation to stop of pressure accumulation by the pressure accumulation control means becomes longer than during normal times. Therefore, by looking at any one of the above-mentioned times, a situation such as a leakage of the hydraulic fluid can be quickly detected.

Of course, the predetermined time for fault determination is such that in normal conditions, the pressure accumulation control means may be one that engages and engages a clutch interposed between the pump and the engine output shaft when the pump is driven by the engine; When the pump is constantly driven by the engine, it can be configured with something like an unloader valve (relief valve) that relieves pressure from the pump to a reservoir tank. Further, the pump can be driven by an electric motor, and in this case, the pressure accumulation control means can be of a type that controls energization of the motor. Of course, the pressure accumulation control means may be an electric type that is activated electrically according to the output of a pressure detection means that detects the pressure in the accumulator, but it may also be a mechanical type that is activated by mechanically detecting this pressure. (It is sufficient if the upper limit value and lower limit value can be detected).

(Example) Examples of the present invention will be described below based on the attached drawings. In addition, the code rFJ used with numbers in the following explanation is for the front wheel, "R" is for the rear wheel, rFRJ is for the right front wheel, and rFLJ is for the left front wheel.

rRRJ means for the right rear wheel, and rRLJ means for the left rear wheel. Therefore, when there is no need to particularly distinguish between them, the description will be made without using these identification codes.

f') E! @M1 prisoner In Figure 1, 1 (IFRlIFL, IRR, IRL
) is a cylinder device provided for each front, rear, left and right wheel, and these are the cylinder 2 connected to the unsprung weight.
and a piston rod 3 extending from inside the cylinder 2 and connected to the unsprung weight. Inside the cylinder 2, a liquid chamber 5 is defined to the north by a piston 4 that is integrated with a piston rod 3, and this liquid chamber 5 and a lower chamber are communicated with each other. As a result, when the hydraulic fluid is supplied to the liquid chamber 5, the piston rod 3 extends and the vehicle height increases, and when the hydraulic fluid is discharged from the liquid chamber 5, the vehicle height decreases.

For the liquid chamber 5 of each cylinder device l, a gas spring 6 (
6FR, 6FL, 6RR16RL) are connected.

Each of the gas springs 6 is composed of four cylindrical springs 7 having a small diameter, and the cylindrical springs 7 are connected to the liquid chamber 5 through an orifice 8 in parallel to each other.

Of these four cylindrical springs 7, except for one, the remaining three are connected to the liquid chamber 5 via a switching valve 9°. As a result, when the switching valve 9 is in the switching position as shown, the four cylindrical springs 7 are communicated only through the orifice 8, and the damping force at this time is small. Furthermore, when the switching valve 9 is switched from the illustrated position, the three cylindrical springs 7 are also communicated with the liquid chamber 5 via the orifice 2 seat 10 built into the switching valve 9, and the damping force is becomes large. Of course, by changing the switching position of the switching valve 9, the spring characteristics of the gas spring 6 are also changed. The suspension characteristics can also be changed by changing the amount of hydraulic fluid supplied to the fluid chamber 5 of the cylinder device 1.

In the figure, reference numeral 11 denotes a pump driven by an engine, and high-pressure hydraulic fluid pumped up by the pump 11 from a reservoir tank 12 is discharged into a common passage 13.

The common passage 13 is branched into a front passage 14F and a rear passage 14R, and the front passage 14F is further divided into a right front passage 14F.
R and a left front passage 14FL. The front right passage 14FR is connected to the liquid chamber 5 of the front right wheel cylinder device IFH, and the front left passage 14FL is connected to the liquid chamber 5 of the front left wheel cylinder device IFL. A pilot valve 16FR serving as a supply flow rate control valve 15FR1 and a delay valve is connected to this front right passage 14FH from its upstream side. Similarly, a supply flow control valve 15FL and a pilot valve 16FL are connected to the left front passage 14FL from its upstream side.

A first relief passage 17FR for the right front passage is connected to the front right passage 14FH from between both valves 15FR and 16FR, and this first relief passage 17FR finally passes through the front wheel relief passage 18F to the reservoir tank 12. It is connected to A discharge flow rate control valve 19FR is connected to the first relief passage 17FH. Moreover, the passage 14FR downstream of the pilot valve 16FR is connected to the first relief passage 17FH via the second relief passage 20FR, and the relief valve 21FR is connected to this. Furthermore, a filter 29FR is interposed in the passage 14FH closest to the cylinder device IFR. This filter 29FR
is the cylinder device IFR and the valve 1 located closest to it.
Located between 6FR121FR and the cylinder device IFR
Abrasion powder generated from the sliding of the valve 18
Prevents it from flowing to the FR121FR side.

Note that the passage configuration for the left front wheel is also configured in the same manner as the passage configuration for the right front wheel, so a redundant explanation thereof will be omitted.

A main accumulator 22 is connected to the common passage 13, and an accumulator 23F is also connected to the front wheel relief passage 18F. This main accumulator 22 serves as a pressure accumulation source for hydraulic fluid together with a sub-accumulator 24 to be described later, and is intended to prevent the amount of hydraulic fluid supplied to the cylinder device 1 from becoming insufficient. Further, the 7-cumulator 23F is provided to prevent the high-pressure hydraulic fluid in the front wheel cylinder assembly Ml from being suddenly discharged to the low-pressure reservoir tank 12, that is, to prevent the water hammer phenomenon.

The hydraulic fluid supply and discharge passages for the rear wheel cylinder devices IRR and IRL are also configured in the same manner as for the front wheels, so a redundant explanation thereof will be omitted. However, there is no equivalent to the pilot valves 21FR and 21FL in the rear wheel passage.
In addition, the main accumulator 22 is located in the rear wheel passage 14R.
A sub-accumulator 24 is provided in consideration of the fact that the passage length from the front wheel is longer than that for the front wheel.

The common passage 13, that is, each passage 14F for the front and rear wheels,
14R is connected to a relief passage 18F for four wheels via a relief passage 25, and a control valve 26 consisting of an electromagnetic on-off valve is connected to the relief passage 25.

In FIG. 1, 27 is a filter, and 28 is a pressure regulating valve as pressure accumulation control means for adjusting the discharge pressure from the pump 11, that is, the pressure accumulated in the accumulator 22, to be within a predetermined range. In the embodiment, the pump 11 is configured as a variable displacement swash plate piston type, and 28 is integrated into the pump 11 (discharge pressure 120 to 160 kg/cm2).

The pilot valve 16 is opened and closed depending on the pressure difference between the pressure in the front and rear passages 14F or 14R1, that is, the common passage 13, and the pressure on the cylinder device 11 side. For this reason,
For front wheel pilot valves 16FR and 16FL,
Common pyro branched from passage 14F=, To passage 31
F is derived, and one of the two branch pilot passages 31 branched from the common pilot passage 31F.
FR is connected to the pilot valve 16FH, and the other passage 3IFL is connected to the pilot valve 16FL.

An ori 2 chair 32F is interposed in the common pilot passage 31F. Note that the pilot passage for the rear wheels is similarly configured.

Each of the pilot valves 16 shown in L is constructed, for example, as shown in FIG. 2, and the one shown is for the right front wheel. This pilot valve 16 has, in its casing 33,
A main channel 34 forming a part of the passage 14FH is formed,
A passage 14FR is connected to the main passage 34. A valve seat 35 is formed in the middle of the main flow path 34, and the opening/closing piston 36, which is slidably inserted into the casing 33, is detached from dust on the valve seat 35, and the pilot valve 1
6FR is opened and closed.

The opening/closing piston 36 is integrated with a control piston 38 via a valve shaft 37. This control piston 38 is
It is slidably inserted into the casing 33 to define a liquid chamber 39 within the casing 33, and the liquid chamber 39 is connected to the branch pilot passage 31FR via a control flow path 40. .

The control piston 36 is then operated by a return spring 41.
, the direction in which the opening/closing piston 36 is seated on the valve seat 35,
That is, the pilot valve 18FR is biased in the closing direction. Furthermore, the pressure of the main flow path 34 is applied to the control piston 38 via the communication port 42 on the side opposite to the liquid chamber 39 . As a result, inside the liquid chamber 39 (common passage 1
3 side) becomes 1/4 or less of the pressure in the main flow path 34 (cylinder device IFR side), the opening/closing piston 36 seats on the valve seat 35 and the pilot valve 16FR is closed.

Here, from the state where the pilot valve 16FR is open,
When the pressure on the common passage 13 side decreases significantly, this pressure decrease is delayed by the action of the orifice 32F, and the pressure decreases in the liquid chamber 39.
Therefore, the pilot valve 16FR is closed after a delay from the pressure drop (in the embodiment, this delay time is set to about 1 second).

(Margin below) Next, the operation of each of the above-mentioned valves will be explained.

(Switching valve 9) In the embodiment, the switching valve 9 is operated to increase the damping force only during turning.

<2) Relief valve 21 The relief valve 21 is normally closed and the cylinder device 1
m pressure is above a predetermined value (160-200 kg in the example)
/cm2), it is opened.

In other words, it serves as a safety valve that prevents the pressure on the shilling device 1 side from rising abnormally.

Of course, the relief valve 21 is the cylinder device 1IR for the rear wheel.
Although it can also be provided for R and IRL, in the example, it is assumed that the vehicle has a weight distribution set to be considerably larger on the front side than on the rear side, and the pressure on the rear wheel side is The relief valve 21 is not provided on the rear wheel side in consideration of the fact that the pressure does not become higher than the pressure of the rear wheel.

Q) Flow rate control valves 15.19 Both the supply and discharge flow rate control valves 15.19 are electromagnetic spool valves that can be switched between an open state and a closed state as appropriate. However, when it is in the open state, it has a differential pressure adjustment function that keeps the differential pressure between the upstream and downstream sides almost constant (due to streamline control, this differential pressure must be kept constant). More specifically, the flow control valve 15.19 changes the displacement position or opening degree of its spool in proportion to the supplied current, and this supplied current is created and stored in advance. It is determined based on the flow rate-current correspondence map. In other words, the supplied current corresponds to the required flow rate when the current is set.

By controlling the flow rate control valves 15 and 19, the supply and discharge of hydraulic fluid to the cylinder device 1 are controlled, thereby controlling the suspension characteristics.

In addition to this, when the ignition is OFF, this O
For a predetermined period of time (2 minutes in the embodiment) from the time of FF, only the control in the direction of lowering the vehicle height is performed. In other words, it takes into account changes in the payload caused by getting off the vehicle, etc., and prevents the vehicle height from becoming partially high (maintaining the standard vehicle height).
.

(4) Control u4 box 26 The control valve 26 is normally closed by being excited, and is opened in the event of a failure. This failure can occur if: (1) For example, if a part of the flow control valve 15.19 is stuck, if the sensors described below fail, if the hydraulic pressure of the hydraulic fluid fails, or if the pump 11 fails. There are cases etc.

In addition, in the embodiment, the control valve 26 is opened after a predetermined period of time (for example, 2 minutes) has elapsed since the ignition was turned off.

Note that when this control valve 26 opens, the pilot valve 1
6 is closed later as described above.

(■Pilot valve 16 As already mentioned, due to the action of the orifices 32F and 32R, it is opened with a delay after the pressure in the common passage 13 has decreased.This means that if a part of the flow control valve 15 is opened, for example, When the failure occurs, the pilot pressure decreases due to the opening operation of the control valve 26, causing the passages 14FR to 14
RL is closed to confine the hydraulic fluid in the cylinder devices IFR to IRL to maintain the east height. Of course, at this time,
The suspension characteristics are fixed to so-called passive characteristics.

Control System FIG. 3 shows a control system for the hydraulic fluid circuit shown in FIG. In this Fig. 3, WFR is the right front wheel, WF
L is the left front wheel, WRR is the right rear wheel, WRL is the left rear wheel,
U is a control unit configured using a microcomputer. This control unit U includes each sensor 51.
FR~51RL, 52FR~52RL, 53FR153
Signals from FL53R154 and 61 to 63 are input, and in addition to these, ON and OFF signals from ignition switch 71 and a signal indicating the operating state of pressure regulating valve 28 are input. Further, from the control unit U, the switching valve 9. The flow control valve 15 (15FR-15RL), 1
9 (19FR to 19RL), output to the control valve 26, alarm lamp, buzzer, etc. ffNi72.

The sensors 51FR to 51RL are connected to each cylinder device IF.
It is installed in the R-IRL and detects the amount of extension thereof, that is, the vehicle height at the valley wheel position. Sensor 52FR~5
2RL is a sensor 5 that detects the pressure in the liquid chamber 5 of each cylinder device IFR-IRL (see also FIG. 1).
3FR153FL and 53R are G sensors that detect downward acceleration. However, on the front side of vehicle B, two G sensors 53FR are installed at almost left-symmetric positions on the front axle.
153FL is provided, but for the rear of vehicle B, one G
Only sensor 53R is provided. In this way,
One virtual plane representing the vehicle body B is defined by the three G sensors, and this virtual plane is set to be a substantially horizontal plane.

]] The sensor 54 detects the pressure of the main accumulator 22. The sensor 61 detects vehicle speed. The sensor 62 detects the operating speed of the steering wheel, that is, the steering angular speed (actually, the steering angle is detected, and the steering angular speed is calculated from the detected steering angle). The L sensor 63 detects the lateral G acting on the vehicle body (in the embodiment, there is a sensor 63 on the Z axis of the vehicle body).
(only one is provided).

The control unit 9U basically performs active control conceptually shown in FIG. control) and vehicle torsion control (pressure signal side u4). The results of each of these controls are ultimately
It is expressed as the flow rate of the working fluid flowing through the flow control cell 15.19 as a flow rate adjustment means.

Active Control Next, let's look at an example of how to control suspension characteristics based on the output of each sensor, as shown in Figure 4.
This will be explained with reference to FIG.

The content of this control can be roughly divided into the most basic attitude control of the vehicle body B based on the output of the vehicle height sensor, ride comfort control based on the output of the G sensor, and torsion suppression control of the vehicle body B based on the output of the pressure sensor. It is divided into the following.

(!') Attitude control (vehicle height sensor signal side m) This control is
Consisting of three attitude controls that suppress bounce, pitch, and roll, each control is controlled by PDviii
Feedback control is performed by control (proportional-derivative control '4s).

For each of these three attitude controls, how to handle the output from each vehicle height sensor is indicated by the "+" and "-" signs shown on the left side of the figure for each control section for bounce, pitch, and roll. This is shown by Furthermore, the "+" and "-" signs shown on the right side of each control section in the figure indicate that each control section controls posture changes. A code opposite to that shown on the left side of the center is given.

In other words, in bounce control, the FD sub-control is performed in a direction in which the added value of each vehicle height on the left and right front sides and the added value of each vehicle height on the left and right rear sides match the reference vehicle height value, and the control formula used for this and S. is shown in the following equation (1).

KB1+ (Ta2- S/ (1+TB2- S)
) -KB2ψ ・ @ (1) KBI, day 2. TB2: Control gain (constant) S: Operator In addition, in pitch control, the FD is adjusted in the direction in which the sum of the added value of the left and right rear vehicle heights is subtracted from the added value of the left and right front vehicle heights, and the value becomes zero. Sub-control. Furthermore, in roll control, the FD is moved in the direction where the added value of each vehicle height on the left front and rear sides matches the added value of each vehicle height on the right front and rear sides (so that the target roll angle is achieved).
Sub-control.

Each of the control values obtained from the three FD sub-controls described above is obtained for each of the four cylinder devices 1, and is added to each other for each control value for each cylinder device 1. Finally, the control values for the four attitude control The flow rate signal QXFR-QXRL,!
: [Determined.

Of course, for both the pitch control and roll control, the control equations for the FD sub-control are in the form of equation (1) above (however, the control gains are set for pitch control and roll control). .

B) G ride comfort control # (G sensor signal control) This ride comfort control is intended to prevent the deterioration of ride comfort caused by the posture control in (2) above. Therefore, in response to the three posture controls in E-0), the I
Feedback control is performed by PD control (integral-proportional-derivative control), and the control equation by this IPD control is shown in the following equation (2).

(Ta3/ (1+ TB3 battle S)) @KB3+K
B40 (Ta3φS/ (1+TB3-S)) Reference KB
3. Fist Fist (2) KO3, KO2, Ta3: Control gain (constant) S: Operator However, in the above equation (2), each control gain is used for bounce control, pitch control, and roll control, respectively. A dedicated one is used.

Since there are only three G-sensors for ride comfort control, the arithmetic average of the front left and right vertical accelerations is used as the front vertical acceleration for the front side control. In addition, during roll control, only the left and right vertical accelerations on the front side are used, and the vertical accelerations on the rear side are not used.

In this ride comfort control as well, the three factors mentioned above are important! Each control value obtained by the FD control is obtained for each of the four cylinder devices l, and is added to each other for each control value for each cylinder l, and finally four flow rate signals Q for ride comfort control are obtained.
GFR-QGRL.

W) Warp control (pressure signal control) Warp control is a control that suppresses torsion of the vehicle body B. Also, since the pressure acting on each cylinder device 1 corresponds to the load on each wheel, control is performed so that the torsion of the vehicle body B due to this load does not become large.

Specifically, feedback control is performed in a direction such that the ratio of the difference and the sum of left and right pressures is 1 for each of the front side and rear side of the vehicle body. The 1 weighting gives a weight to each torsion point on the front and rear sides of the vehicle body using the coefficient ωF, and the weighting gives a weight to each of the above-mentioned controls (1) and (2) using a coefficient ωA. . Of course, even in this torsion suppression control, the control value is ultimately determined by the flow rate signal QPFR-QPRL (
%).

The flow signals for attitude control, first ride comfort control, and torsion suppression control determined for each of the four cylinder devices as described above are finally added to form a final flow signal QF.
It is determined as R-QRL.

=r):4(, The control gain of the control formula used in the explanation of FIG. 4 is switched and controlled by a control system as shown in FIG.

First, the steering angular velocity θ is multiplied by the vehicle speed V, and the value S1, which is a reference value G1 calculated from the result θN·■, is input to the turning determination section. Also, the current lateral acceleration G of the vehicle
A value S2 obtained by subtracting the reference value G2 from s is input to the turning determination section. Then, in the turning determination section, input Sl or S2≧0
In this case, it is determined that the vehicle is turning, and the suspension characteristic hardening signal 5at- is output, and the damping force switching valve 10 is set to the throttle position in order to improve the followability of flow control for each hydraulic cylinder 3. At the same time, each ratio measurement aKi (i=Bt-84) is set to the entry KHard, and each target roll TROLL is set to a value corresponding to the lateral acceleration Gs at that time from a map stored in advance. An example of this map is shown in FIG. By the way, in the case of a passive suspension vehicle, as shown in Figure 5S7, as the lateral G increases, the roll angle (positive roll) increases.
If it is thick, it is determined that the vehicle is traveling straight, and the suspension characteristic softening signal sb is output, and the damping force switching valve lO
are switched to the same position, the ratio measurement aKi is set to the normal value Ksoft, and the target roll angle TPOLL=0.
Set to .

Control Corresponding to the Operating Condition of the Pressure Regulating Valve 28 Next, a description will be given of how control is performed corresponding to the operating condition of the pressure regulating valve 28.

First, as shown in FIG. 8, when the pressure regulating valve 28 is opened (pump pressure is relieved by cutout), the pressure is 160.
kgf/cm2, and the pressure regulating valve 28 is closed (
When the pump pressure relief stops at cut-in), the pressure is 1.
It is 20 kgf/cm2. The time from cut-out to cut-in is indicated by tl, and the time from cut-in to cut-out is indicated by t2. and,
If the time t1 is less than or equal to the first predetermined time, or if the time t2 is greater than or equal to the second predetermined time, a failure occurs. However, in this embodiment, 1.
1: A failure is finally determined only when the failure determination as described above occurs five times in a row. When a failure is determined in this way, in the embodiment, the active control is immediately stopped at the time when the failure is determined, and the relief control valve 2 is
6 and activate the alarm 72.

Based on the above, the flowchart shown in FIG. 9 will be explained. In this case, S indicates a step in the following description. Further, the flag F indicates a case where a failure is determined when the pressure of the anemulator 22 is l.

It is executed on the premise that it is equal to or greater than Okgf/cm2, and when the flag F becomes 1, it is turned off.

First, after the system is initialized at step S1, signals from each sensor or switch are input at step S2. Next, it is determined at SS whether the flag F is 1 or not. If this SS judgment is No,
In s4, it is determined whether or not the pressure regulating valve 28 is cut in.

, If the determination in S5 is YES, the time t1 from cut-out to cut-in is calculated in s6, and then 1. is less than or equal to a predetermined value (first predetermined time). If the determination at S6 is YES, the counter CA is counted up, and then it is determined at SS whether the count value is 5 or more.

If the SS determination is YES, the flag F is set to 1 in s9, and then the process moves to Sll. If the judgment in S6 above is No, the counter CA is set to 0 at 510.
After resetting to
If o, the process directly advances to S11.

On the other hand, when the determination in S4 is No, it is determined in S12 whether or not the pressure regulating valve 28 is cut out. When the determination in S12 is YES, 513 to SI8
This process corresponds to the process from 85 to SIO. That is, t2 in FIG. 8 is calculated in S13, the predetermined value to be compared with t2 in S14 is the second predetermined time, and the counter used is CB.

If the determination in S12 is NO, the process directly proceeds to S11. In this Sll, it is determined whether or not the ignition switch 71 has been turned off, and if the determination is No, the process returns directly. Further, when the determination of Sll is YES, the flag F is reset to O in 319, and then the process is terminated. Through the process of S19, when the ignition switch 71 is turned ON again,
There is a possibility that active control will be performed again.

(Effects of the Invention) As is clear from the above description, the present invention makes it possible to quickly detect the occurrence of a malfunctioning vehicle condition that causes a shortage of hydraulic fluid.

Further, since it is only necessary to monitor the operating state of the existing pressure accumulating means, it can be easily implemented.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and is a diagram showing a hydraulic fluid circuit. FIG. 2 is a sectional view showing an example of the pilot valve in FIG. 1. z3 is a diagram showing a control system of the circuit shown in FIG. 1. FIGS. 4 and 5 are overall system diagrams showing an example of active control. FIG. 6 is a diagram showing an example of roll characteristics in an active suspension vehicle. FIG. 7 is a diagram showing an example of roll characteristics in a passive suspension vehicle. FIG. 8 is a diagram showing changes in the operating state of the pressure regulating valve and the corresponding relationship between pressure and time. FIG. 9 is a flowchart showing a control example of the present invention. FIG. 10 is a block diagram showing the overall configuration of the present invention. U: Control unit IFR-IRL Nijilinda device 5: Liquid chamber 11: Pump 15FR~15RL 19FRN19RL: Reservoir tank: Supply control valve: Discharge control valve: Accumulator: Pressure regulating valve (pressure accumulation control means) Patent applicant: Nardec Co., Ltd. Mazda Motor Corporation 4゜3 Kusakataira = Japan〈・1をdetective'Nbienjin゛minute))? Talk 1 and look at the sky) PRL ↑ 6 Figure 1 Zuin1 ugly men 1 Maki G Figure 8

Claims (2)

[Claims] (1) A cylinder device that is installed between the sprung weight and the unsprung weight and changes the vehicle height according to the supply and discharge of hydraulic fluid, and pumps up the hydraulic fluid in the reservoir tank and discharges high-pressure hydraulic fluid. a pump as a pressure generation source; an accumulator for accumulating discharge pressure from the pump; and when the pressure of the accumulator reaches a predetermined lower limit, the accumulator is made to accumulate high-pressure hydraulic fluid; a pressure accumulation control means that stops accumulating pressure in the accumulator when a predetermined upper limit value greater than the lower limit value is reached; and a supply control valve for supplying the hydraulic fluid accumulated in the accumulator to the cylinder device; and a discharge control valve for releasing hydraulic fluid from the cylinder device to the reservoir tank, and supply and discharge of hydraulic fluid to and from the cylinder device by controlling the supply and discharge control valve according to predetermined conditions. A vehicle comprising: supply/discharge control means for controlling; and failure determination means for determining a failure when the time from the stop of pressure accumulation to the start of pressure accumulation by the pressure accumulation control means is less than or equal to a predetermined time. suspension equipment. (2) A cylinder device that is installed between the sprung weight and the unsprung weight and changes the vehicle height according to the supply and discharge of hydraulic fluid, and pumps up the hydraulic fluid in the reservoir tank and discharges high-pressure hydraulic fluid. a pump as a pressure generation source; an accumulator for accumulating discharge pressure from the pump; and when the pressure of the accumulator reaches a predetermined lower limit, the accumulator is made to accumulate high-pressure hydraulic fluid; a pressure accumulation control means that stops accumulating pressure in the accumulator when a predetermined upper limit value that is larger than the lower limit value is reached; and a supply control valve that supplies the hydraulic fluid accumulated in the accumulator to the cylinder device; and a discharge control valve for releasing hydraulic fluid from the cylinder device to the reservoir tank, and supply and discharge of hydraulic fluid to and from the cylinder device by controlling the supply and discharge control valve according to predetermined conditions. A vehicle characterized by comprising: supply/discharge control means for controlling; and failure determination means for determining that there is a failure when the time from the start of pressure accumulation to the stop of pressure accumulation by the pressure accumulation control means is a predetermined time or more. suspension equipment.