JPH0463713A - Suspension for vehicle - Google Patents

Abstract

PURPOSE:To early detect failure in supply and exhaust control valves by comparing the operating condition of a cylinder, mounted between a body and a wheel to adjust the level of the body, with that of other cylinders to judge whether in trouble or not. CONSTITUTION:Suspensions comprises cylinders 1(1FR-1RL) provided on respective front-rear-right-left wheels, and liquid rooms 5 in the cylinders 1 are connected with gas springs 6 (6FR-6RL) and connected to a pump 11 or a reservoir tank 12 via supply control valves 15 (15FR-15RL), exhaust control valves 19 (19FR-19RL). A controller controls respective valves 15, 19 corresponding to the driving conditions of a vehicle, thereby to perform the attitude control of the body. In this case, the controller compares the operating condition of the cylinder 1 with that of other cylinders 1 to judge whether in trouble to prevent normal attitude control or not and thereby to see whether supply and exhaust control valves 15, 19 are normally operated or not.

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, a system called an active suspension has been proposed in which the suspension characteristics can be changed arbitrarily. In this active suspension, basically, a cylinder device is installed between each wheel and the vehicle body, and by controlling the supply and discharge of working fluid to the cylinder device through the supply and discharge control valve, Suspension characteristics are changed (Unexamined Japanese Patent Publication No. 6
3-130418).

In this active suspension, by supplying and discharging working fluid from the outside, the suspension characteristics can be greatly changed for various posture controls such as vehicle height control, roll control, and pitch control (this is the problem that the invention seeks to solve). Problem) By the way, while the working fluid for active suspensions is incompressible, that is, working fluid, there are systems in which the supply/discharge control valve is of a flow rate control type from the viewpoint of ensuring smooth control. That is, it has been considered to use a flow signal as a control signal for a supply/discharge side fit valve for attitude control. In this case, the flow control type feed control valve is generally equipped with a differential pressure valve for maintaining the differential pressure between the population side and the outlet side at a predetermined pressure.

The supply/discharge control valve equipped with the differential pressure valve mentioned above is made with extremely high precision to prevent leakage of hydraulic fluid. Therefore, if foreign matter such as dust gets caught in the supply/discharge control valve, the supply/discharge control valve will not operate properly. This is likely to occur more frequently.

The present invention was made in consideration of the above-mentioned circumstances, and
It is an object of the present invention to provide a suspension device for a vehicle that can determine whether or not a supply/exhaust control valve is no longer operating normally.

(Structure, operation, and effect of the invention) In order to achieve the above object, the present invention basically has the following structure. In other words, it is a flow control type equipped with a cylinder device installed between the vehicle body and each wheel, which adjusts the vehicle height according to the supply and discharge of hydraulic fluid, and a differential pressure valve, and controls the flow of hydraulic fluid to the front two cylinder devices. A supply/discharge control valve that performs supply/discharge.

By comparing the operating state of each cylinder device with the attitude control means that controls the attitude of the vehicle body by outputting a flow rate side fil signal to the supply/discharge control valve based on predetermined conditions. , and a failure determining means for determining whether a failure has occurred that would prevent the attitude control from being performed normally.

When a certain supply/discharge control valve malfunctions, especially when its differential pressure valve becomes inoperable due to dirt clogging, etc., the operating state of the cylinder device will be such that hydraulic fluid is supplied and discharged by the normal supply/discharge control valve. The operating conditions are quite different from those of the bale cylinder device. Therefore, by comparing the operating states of each cylinder device, it is possible to know whether the supply/discharge control valve is operating normally.

To compare the operating conditions of each cylinder device, its internal pressure,
Alternatively, it can be performed based on the vehicle height at a position corresponding to each cylinder device (corresponding to the amount of expansion and contraction of the cylinder device). When performing this comparison, since the operating state of each cylinder device may change significantly if only a certain moment is captured, it is necessary to compare the operating state within a predetermined period of time so that the changes at this moment can be absorbed. It is a good idea to do this.

If a malfunction is determined, at least the supply and discharge control valve for the cylinder device that is found to be malfunctioning should be forcibly vibrated, that is, repeatedly opened and closed, to remove debris that has become clogged in the supply and discharge control valve. This is preferable for removal.

Dust clogging in the supply/discharge control valve often clears up naturally. Therefore, even when a failure has occurred (↑1), it is preferable to cancel this failure determination after turning the ignition switch OFF in order to ensure the possibility of performing attitude control after turning the ignition switch ON again. becomes. In this case, once a failure has been determined, it is preferable to weaken the degree of attitude control, that is, to perform attitude control with its control gain reduced. Even if the attitude control is performed with this low control valve gain, if the failure e1) is not determined, the control valve gain is changed to the normal control gain.
Just let M go home.

(Example) Examples of the present invention will be described below based on the attached drawings. In addition, the code "F" used with numbers in the following explanation is for the front wheel, rRJ is for the rear wheel, rFRJ is for the right front wheel, rFLJ is for the left front wheel, rRRJ is for the right rear wheel, rRL
It is clear that J is for the left rear wheel, and therefore, when there is no particular need to distinguish between them, the description will be made without using these identification symbols.

In the hydraulic fluid circuit diagram 1,] (IFR1IFL, IRR, 1RL
) is a cylinder device provided for each front, rear, left and right wheel, and these are the cylinder 2 connected to the unsprung heavy axle.
and a piston rod 3 extending from inside the cylinder 2 and connected to a spring. Inside the cylinder 2, a liquid chamber 5 is defined in the L direction by a piston 4 integrated with a piston rod 3, but 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 2 and the vehicle height becomes higher, and when the hydraulic fluid is discharged from the fluid chamber 5, the vehicle height becomes lower.

For the liquid chamber 5 of each cylinder device l, a gas chamber 6 (
6FR56F L, 6RR16R1, -) 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 through the orifice 10 built into the switching valve 9, resulting in a large damping force. Become something. Of course, by changing the switching position of the switching valve 9, the spring characteristics of the gas spring 6 are also changed. This suspension characteristic 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, 1) is a pump driven by an engine, and pump 1) discharges high-pressure hydraulic fluid >D k- from a reservoir tank 12 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 branched into a right front (1) 1 passage 14FR and a left front 1ful 1 passage 14FL. This front right passage 14FR is connected to the liquid chamber 5 of the cylinder device IFR for the right front wheel, and is also connected to the front left passage 14F.
T is connected to the liquid chamber 5 of the right front wheel cylinder device IF+. In this right front passage 14FR, the t-
A supply flow rate control valve +5FR1 and a pilot valve +6FR as a delay valve are connected from the 1fL side. Similarly,
The supply flow rate control valve 15F is also connected to the left front passage 14FL from the flow side. , pilot valve 16F +-7 is connected.

Right front passage + 4FR has one valve] A first relief passage 17FR for the right m1 side passage connects between 5FR and 16FR, and this first relief passage 17FR finally passes through the front wheel relief passage 18F. It is connected to Nozarbakunku 12. And in the 5th first relief passage + VFR,
A discharge flow control valve 19FR is connected. Further, the passage 14FR downstream of the pilot valve 16FR is connected to the first relief passage 17FR via the second relief passage 20FR, and a relief valve 21FR is connected to this.

Furthermore, in the passage 14FR closest to the cylinder device IFR,
A filter 29FR is provided. This filter 29
FR is located between the cylinder device IFR and the nearest valve 16FR121FR, and is located between the cylinder device IFR and the nearest valve 16FR121FR.
This prevents wear particles generated from sliding of the FR from flowing toward the valve 16FR12IFR.

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 2'3'F is also connected to the front wheel relief passage 18F. This main accumulator 22 is a sub accumulator 2 which will be described later.
Together with 4, it serves as a pressure accumulation source for the hydraulic fluid, and is used to prevent the amount of hydraulic fluid supplied to the cylinder device 1 from becoming insufficient. Further, the accumulator 23F is provided to prevent the high-pressure hydraulic fluid in the front wheel cylinder device l from being suddenly discharged to the low-pressure reservoir tank 12, that is, to prevent the water hammer phenomenon.

The hydraulic fluid and supply/discharge passages for the rear wheel cylinder devices IR, R1I and RI- are also constructed 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 valve 21FR521F L in the rear wheel passage, and the length of the passage from the main accumulator 22 in the rear wheel passage 14R is longer than that for the front wheels. For this reason, a sub-accumulator 24 is provided.

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

In addition, 27 in FIG. 1 is a filter, and 28 is a pressure regulating valve for adjusting the discharge pressure from the pump 1) to be within a predetermined range.
The pump is configured as a variable displacement type tilted piston type and is integrated into the pump 1) (with a discharge pressure of 12
0-160kg/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 in one example of the cylinder device. For this reason,
For front wheel pilot valve +6FR, 16FL,
A common pilot passage 31F branched from the passage 14F is led out, and of the two branched pilot passages branched from the common pilot passage 31F, one passage 31FR is connected to the pilot valve 16FR, and the other passage 3IF is connected to the pilot valve 16FR.
L is connected to the pilot valve 16FL.

An orifice 32F is provided in the common pilot passage 31F. Note that the pilot passage for the rear wheels is similarly configured.

Each of the pilot valves 16 is configured as shown in FIG. 2, for example, 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 +4FR is formed,
A passage +4FR is connected to the main passage 34. F
A valve seat 35 is formed in the middle of the article flow path 34, and the opening/closing piston 36, which is slidably inserted into the casing 33, is seated on and off the valve seat 35, thereby opening 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 connected to the return spring IJ ring 4.
1, the opening/closing piston 36 is biased in the direction in which it is seated on the valve seat 35, that is, in the direction in which the pilot valve 16FR is closed. Furthermore, the control piston 38 has a communication port 42.
The pressure of the royal flow path 34 is applied on the side opposite to the liquid chamber 39 via. As a result, the pressure in the liquid chamber 39 (on the common passage 13 side) is reduced in the main passage 34 (in the cylinder device IFR
When the pressure becomes 1/4 or less of 1) IIl), the opening/closing piston 36 seats on the valve seat 35 and the pilot valve +6FR is closed.

Here, from the state where the pilot valve 16FR is open,
When the pressure in the 13 common passages 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 with a delay from the pressure drop (in the embodiment, this delay time is set to about 1 second).

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.

・■Relief valve 21 The J leaf valve 21 is normally idle, and the pressure of the cylinder)
When it becomes 00 kg/Cm21, it is opened.

In other words, it serves as a safety valve that prevents the pressure in one example of the cylinder device from rising abnormally.

Of course, the relief valve 21 is a cylinder device IRR for the rear wheels.
1I RT, etc., but in the example, it is assumed that the vehicle has a heavy @ type portion set much larger on the front side than on the rear side, and the pressure on the rear wheel side is The J leaf valve 21 is not provided on the rear wheel side in consideration of the fact that the pressure does not become larger than the pressure on the front wheel side.

(2) Flow rate control valves 15, I9 Both the supply and discharge flow rate control valves 15 and 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 flow side and the downstream side almost constant (during flow rate control, this differential pressure is kept constant). ). More specifically, the flow control valve 15.19 changes the displacement position, that is, the opening degree, of its spool in proportion to the supplied current. Determined based on map. That is, the supplied current corresponds to the required flow rate at that time.

By controlling the flow rate control valves 15 and 19, the supply and discharge of hydraulic fluid to the cylinder device 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, the control valve 26 prevents the vehicle height from becoming partially high due to changes in the load caused by getting off the vehicle (maintaining the standard vehicle height). It is normally closed when it is energized and opened when it fails. This failure can occur, for example, if a part of the flow control valve 15.19 becomes stuck, if the sensors described below fail, if the hydraulic pressure of the hydraulic fluid fails, or if pump +1 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
As mentioned above, it is closed after 6 seconds.

■Pilot valve 16 As already mentioned, the pilot valve 16 is opened with a delay after the pressure in the common passage 13 decreases due to the action of the orifices 32F and 32R. This means that, for example, in the event of a failure in which a part of the flow rate control valve 15 remains open, the pilot pressure decreases due to the opening operation of the control valve 26, causing the passage 14FR~]4
Rl is closed to confine the hydraulic fluid in the cylinder devices IFR to IRJ, and maintain the vehicle height. Of course, at this time, the suspension characteristics are fixed to what is called a passive characteristic.

Control System FIG. 3 shows a control system for the hydraulic fluid circuit shown in FIG.

In FIG. 3, WFR is the right front wheel, WFL is the left front wheel, WRR is the right rear wheel, WRL is the left rear wheel, and U is a control unit configured using a microcomputer. This control unit U includes each sensor 51FR to 51.
R1,, 52FR~52RL, 53FR, 53Fi,
, Fi3R, and signals from 61 to 64 are inputted, and from the control unit U, the switching valve 9, the flow rate control valve 1
5 (15FR-15RI,), 19 (,19FR~
19RIl and the control valve 26.

The sensors 51FR to 51RL are connected to each cylinder device IF.
It is provided at R to IRL to detect the amount of extension, that is, the vehicle height at each wheel position. Sensor 52FR~5
2RL detects the pressure in the liquid chamber 5 of each cylinder device IFR to IRL (see also FIG. 1). The sensors 53 FR253FL and 53R are G sensors that detect acceleration in the vertical direction. However, on the front side of the heavy vehicle B, there are two G sensors 53F located almost symmetrically to the left on the front axle.
R253F[, is provided, but for the rear part of the vehicle, only one G sensor 53R is provided at the left and right intermediate position on the rear axis. 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 61 is for detecting vehicle speed. The sensor 62 detects the operating speed of the steering wheel, that is, the steering angle speed. The sensor 63 detects the lateral G acting on the vehicle body (in the embodiment, only one sensor is provided on the Z axis of the vehicle body). The sensor 64 detects the pressure in the main accumulator 22. The switch 65 is used to select control characteristics for attitude control, and this point will be described in detail later.

The control unit U basically performs active control conceptually shown in FIGS. 4A and 4B, that is, in the embodiment, the vehicle attitude system! 1 (vehicle height signal control and small height displacement speed control), ride comfort control (-F lower acceleration signal control), and vehicle torsion control @ (pressure signal control).The results of each of these controls are , is finally expressed as the flow rate of the working fluid flowing through the flow rate control valve 15.19 as a flow rate adjustment means.

(Left below) Active control Next, an example of how to control the suspension characteristics based on the output of each sensor is shown in Fig. 4A.
This will be explained with reference to FIG. 4B.

The content of this control can be roughly divided into control systems X1 and X2 that control the attitude of the heavy body B based on the output of the most basic vehicle height sensor and its derivative (# (vehicle height displacement speed)), and the output of the G sensor. It consists of a control system X3 that performs ride comfort control based on the pressure sensor, a control system X4 that performs torsion suppression control of the vehicle body B based on the output of the pressure sensor, and a roll vibration reduction side @X5 based on the output of the lateral G sensor 63. , will be explained below.

■Control nX] (vehicle height displacement component) This control consists of three posture-side controls that suppress bounce, pitch, and roll, and each control includes feedback control using P control (proportional control). be done.

First, reference numeral 70 indicates vehicle height sensors 5'lFR to 51RL,
Of these, the outputs XFR and XFL of the left and right front wheels are summed, and the output XRR of the left and right rear wheels is calculated.

This is a bounce component calculation unit that totals the XRL and calculates the bounce component of the vehicle. Reference numeral 71 indicates the output X of the left and right rear wheels from the total value of the outputs XFR and XFL of the left and right front wheels.
This is a pitch component calculation unit that calculates the pitch component of the vehicle by calculating 1& the total value of RR and X old. Reference numeral 72 indicates the difference in output between the left and right front wheels, XFR-X Fl. This is a roll component calculation unit that adds the difference X RR - X RL between the outputs of the left and right rear wheels, and calculates the roll component of both wheels.

Reference numeral 73 indicates the bounce component of the vehicle that has been oiled by the i2 bounce component calculation unit 70 and the target average vehicle height determination unit 91
This is a bounce control unit which receives a target vehicle height signal TI (from 74) and calculates a control amount for the flow rate control valve of each wheel in bounce control based on the gain coefficient.
The pitch component of the vehicle calculated by the pitch component calculation section 71 and the target pitch amount Tp from the pitch amount determination section 92 are input, and the pitch component corresponds to the target pitch i'rp based on the gain coefficient KPI. This is a pitch control wholesaler that calculates the control amount of each flow rate control valve in pitch control so that the vehicle height is achieved. Reference numeral 75 receives the vehicle roll amount calculated by the roll component calculation unit 72 and the target roll amount TR from the target roll determination unit 93, and inputs the gear ratio RKRFI.
2) This is a roll control unit that calculates the control amount of each frL amount control valve in roll control based on KRRI.

In order to control the small height to the target vehicle height, the Moekiya control unit 7
3.7 At 4.75, each @p control is reversed for each wheel (vehicle height sensors 51FR to 51 RL,
Then, the bounce and pitch 50-wheel control amounts for the four-ton wheel are added, and in the control system x 1, the corresponding h-hi Example flow rate signal of flow control valve QFRI, QFLI
, QRRI and QRLI are obtained.

Here, the target vehicle height TH is 1, for example, the general low ground of the vehicle -
In the case of F height, it can be kept at a certain constant value, for example 150 mm. Also, target vehicle height T
H can also be changed. In this case, for example, TH can be changed stepwise or continuously depending on the vehicle height (for example, when the vehicle speed is 80 km/h or higher, the minimum The ground clearance will be 130mm).

Note that the target pitch amount Tp and target roll amount TR will be described later.

・■ System [In the wholesale system X2 (vehicle height displacement speed component) control system x2, pitch control and roll system (distribution) are performed.

First, the pitch component from the pitch component calculation section 71 and the target pitch ring TP are input to the pitch control section 78 . This pitch control unit 78 controls the rate of change of the pitch component (which is the deviation between the vehicle height at the front of the vehicle body and the vehicle height at the rear of the vehicle body) in the direction away from the target pitch amount TP, that is, the rate of change from the vehicle height sensors 51FR to 51RL. The amount of change in the signal sampling time (in the example, the amount of change is determined every 10m5ecl.Then, the control gain KP2 is used to control each flow rate control valve so that the rate of change in the direction of increasing the pitch amount becomes smaller. Deciding on the weather.

Further, the roll amount (roll angle) from the roll amount calculation section 72 and the target roll amount TR from 9 are input to the roll control section 79.This roll control section The section 79 sets a control gain K RF2 for each set of left and right front wheels and left and right rear wheels so that the rate of change in the actual roll amount in the direction away from the target roll decay TR becomes smaller.
Alternatively, KRR2 is used to determine the control flow rate for each flow control valve.

The control amounts determined by each of the control units 78 and 79 are reversed in sign and then added to each flow rate control valve (each cylinder device IFR to lR1) i to control the control flow rate QFR2° in the control system x2. QFL2, QRR2) QRL
2 is determined. Note that "S" shown in each control unit 78 and 79 is an operator showing an image component.

■Control system X3 (vertical acceleration component) First, reference numeral 80 indicates three L lower front speed sensors 53FR1.
Outputs GFR and GFL of 53F L and 53R.

This is a bounce component calculation unit that totals the GR and calculates the bounce component of the vehicle. Reference numeral 81 indicates the pitch component of the vehicle by subtracting the rear wheel side output GR from the total value of each half value of the left and right front wheel side outputs GFR, GFL among the three vertical acceleration sensors 53FR153FL, 53R. This is a pitch component calculation unit that calculates. Reference numeral 82 denotes a roll component calculation unit that calculates a roll component of the vehicle by subtracting the output GFL of the left front wheel from the output GFR of the right front wheel.

The reference numeral 83 receives the bounce component of the vehicle calculated by the bounce component calculation unit 80, and the gain coefficient K
This is a bounce control unit that calculates a control unit for the flow rate control valve of each electric wheel in bounce control based on B3. code 8
Reference numeral 4 denotes a pitch control unit to which the pitch component of the vehicle calculated by the pitch component calculation unit 81 is input, and calculates the control amount of each flow control valve in pitch control based on the gain coefficient KP3. Reference numeral 85 receives the roll component of the vehicle calculated by the roll component calculation unit 82, and calculates the gain coefficient KRF3.
, KRR3 is a roll control unit that calculates the control amount of each Kiyosato control valve in roll control.

In order to suppress the downward vibration of the vehicle with a bounce component, a vibration component, and a roll component, the control quantities calculated by each of the control units 83 to 85 are reversed in sign for each vehicle transport, and then, The bounce, pitch, and roll control amounts for each wheel are added, and in the control system x3, the flow signals of the corresponding proportional flow control valves QFR3, GFL3, QR
R3 and QRL3 are obtained.

(2) Control System x4 First, a wave control section 90 is provided, which includes a front wheel side hydraulic pressure ratio calculation section 90a and a rear wheel side hydraulic pressure ratio calculation section 90b.

The front wheel side hydraulic pressure ratio calculating section 90a calculates the hydraulic pressure signal P FR,' of the two front wheel side hydraulic pressure sensors 52FR152FL.
When P FL is input, the total hydraulic pressure on the front wheel side CP PR+
PFL) versus the left and right fluid pressure difference (PFR-PFl,
) ratio (P FR-P Fl-) / I P FR+
P Fl, ) is calculated. Further, the rear wheel side hydraulic pressure ratio calculating section 90b calculates a similar hydraulic pressure ratio (PRR-PRlj
/ (PRR+PR1,) is calculated.

Then, after multiplying the rear wheel side hydraulic pressure ratio by a predetermined value by a gain coefficient ωF, this is subtracted from the front wheel side hydraulic pressure ratio, and the result is multiplied by a predetermined value by a gain coefficient ωF, and for the front wheels, a predetermined value is obtained by a gain coefficient ωC. Then, the control amount B for each wheel is reversed to equalize it between the left and right wheels, and in the control system x4, the flow rate signals QFR4 and GFL4 of the corresponding flow rate control valves are
, QRR4, and QRL4 are obtained.

Control system x5 (lateral G component) Control detection X5 is performed based on the signal from the lateral G sensor 63 to suppress increase in lateral G acting on the vehicle body and reduce roll vibration. In this control system x5, the signal obtained by the control section 100 based on the control gain KG is
The signs are reversed between the right heavy wheel and the left g1) wheel, and the flow signals of the corresponding flow control valves QFR5, GFL5, QRR
5. QRL5 is obtained. Then, the control ratio between the front side and the rear side is changed by the coefficient AGF.

■Synthesis of each control system x1 to x4 Vehicle height displacement components QFRI, QFLI of the flow rate signal determined for each flow rate control valve as described above.

QRRI, QRLI, vehicle height displacement speed component QFR2
゜QF[,2)QRR2)QRL2, L lower front speed component QFR3, QFI,3, QRR3, QRL3
, pressure components QFR4, GFL4, QRR4, QRL
4, Lateral G component QFR5°QFI, 5, QRR5,
QRL5 is finally added to obtain the final total flow signals QFR, QFL, QRR, and Q'.

An example of the q-type setting of the control gain, etc. used in FIGS. 4A and 4B is shown in Table 1 of the first order.

Table 1 In this Table 1, the meanings of the symbols not shown in FIGS. 4A and 4B are as follows. First, XH is compatible with small and high signals and is used to set its dead zone.

GG corresponds to the downward and lateral G sensors, and is used to set their dead zones. Q MAX is for setting the maximum flow rate limit for inflow and outflow. P MAX is for inlet pressure limit setting, and P MIN is for outlet pressure limit setting.

Furthermore, in Table 1, modes 1 to 7 are set, and the settings of each mode are as follows. First, mode 1 is used for 60 seconds after the engine is turned off, and is used to prevent 1L of vehicle height change while the vehicle is stopped. Mode 2 is used when the vehicle speed is zero, and is for maintaining the vehicle posture. Modes 3 to 7 are used while driving, with mode 3 emphasizing ride comfort, mode 4 setting for reverse roll, and mode 5 aiming for both ride comfort and handling stability. Moto 6 is a setting that aims to achieve both ride comfort and posture maintenance, and Mode 7 is a setting that emphasizes steering stability and i. This is mode 3~
The setting of the usage area of mode 7 can be changed using heavy speed and lateral G as parameters as shown in Figure 5 or Figure 6, and switching between the modes shown in Figures 5 and 6 can be done using a separately provided mode changeover switch. 65 (see Figure 3). Note that the target height TH is changed according to the vehicle speed based on a predetermined standard vehicle height (e.g., equivalent to 160 mm in minimum ground clearance).
The target roll vehicle height TR is changed using the lateral G as a parameter.

When changing modes between modes 1 to 7, transitions to higher modes, such as from mode 3 to mode 5 or mode 6, occur immediately without delay. On the other hand, when transitioning to a low mode, for example, when transitioning from mode 7 to mode 5 or mode 3, the mode is successively decreased one by one, and each predetermined amount is set each time this one moto decreases. The delay time is set. More specifically, considering the case of transitioning from mode 7 to mode 5, mode 7 - delay time elapsed - mode 6 -
Delay time elapsed - Mode 5 is changed.

Detection of failures in equipment and how to deal with them Next, we will explain how to detect failures in equipment used for active system (wholesale) and how to deal with them.

First, in this embodiment, there are three types of responses when a failure is detected, namely failure mode A, failure mode B, and failure mode C.

Failure mode A/Failure mode A is performed by immediately stopping active control at the time of failure detection, opening the relief control well 26, and activating the seventh alarm 72.

Failure mode B/failure mode B: When a failure is detected, the discharge control valve 19 is fully opened for one second to discharge the working fluid from each cylinder device 1 at the maximum flow rate for one second), and then the relief control well 26 is fully opened for one second. At the same time, the alarm 72 is activated.

Failure mode C: Failure mode C corresponds to a minor failure and simply activates the alarm 72.

Among the failure modes A, B, and C, for the failure moto C, when the ignition switch 71 is turned OFF and then turned ON again, active control is started again (active control is restored). On the other hand, in the case of failure modes A and B, depending on the failure details, when the -B ignition switch 71 is turned off and then turned on again, active control is permitted (active control may return). There are two types: 1) and 1) when active control is suspended (no possibility of recovery).
Also, the case of rOJ indicates the case where there is no possibility of recovery. That is, in the following explanation, for example, when failure mode is indicated as A-1, it means that the failure mode is A and there is a possibility of recovery of active control, and when it is indicated as A-0,
This shows a case where there is no possibility of restoring active control even if the failure mode A is the same.

Next, the relationship between the details of the failure and the corresponding failure mode will be explained below.

Immediately after the ignition switch is turned on, all switching valves 9 are set to the hard switching position, but if all switching valves 9 are not at the hard switching position even after 2 seconds have passed since the ignition switch 71 was turned on, It is determined that the switching valve 9 is at fault, and each switching valve 9 is controlled to be in the soft switching position (failure mode 8-1).

The main accumulator 2 is detected by the sensor 64 even after 5 seconds have passed since the ignition switch 71 was turned ON.
When the pressure of 2 does not exceed 30 kgf/cm2 (failure mode A-0).

When the ignition switch 71 is turned on and the actual vehicle height is 30 mm lower than the reference vehicle height (failure mode C
).

Five seconds after the relief control valve 26 is turned off,
Main accumulator 22 pressure is 30kgf/cm2
In the above cases (failure mode 8-0).

When the output signal of the pressure sensor 64 is 4.5 or more (1~
The range of 4■ is a normal output value and failure mode A-0).

When the output signal of the pressure sensor 64 is 0.5V or less (failure mode A-1).

When the output signal of the pressure sensor 64 indicates 185 kgf/Cm2 or more (failure mode A-0).

The output signal of the pressure sensor 64 is 100 kg f/
If the output signal of the pressure sensor 64 does not show a pressure increase for 5 seconds or more when the active control is disabled with a pressure below cm2 (failure mode A-O).

When the time from cut-out to cut-in of unloading by the pressure regulating valve 28 is 1 second or less, and it occurs for 5 consecutive seconds (failure mode 8-1).

The change in the output signal from the pressure sensor 64 in 1 second is 2
kgf/cm2 or less continues for 10 minutes or more (failure mode A-0).

Even though the pressure regulating valve 26 is in the cut-in state, the amount of change in the output signal from the pressure sensor 64 per second is 2 kg.
f/cm2 or less for 5 seconds or more (failure mode 8-0).

Sensor 53 or 63 that detects vertical G or lateral G
When the output signal of the pressure sensor 64 detects a change of O, lG or more, if the output signal of the pressure sensor 64 does not change by more than 2 kgf/cm2 per second for 5 seconds (Failure mode A
-1).

If the output signal from the pressure sensor 64 does not change by more than 2 kgf/cm2 for 1 second after it is detected that the wheel bump amount is 30 mm or more (failure mode 8). -1).

When the pressure sensor 64 detects a pressure of 90 kgf/am2 or less (failure mode A-1).

When each sensor or actuator is disconnected (failure mode A-0).

Is it possible that the operating flow rate in the reservoir rank 12 has fallen below a predetermined lower limit? When detected on u (failure mode A-0).

When the output signal of each cylinder pressure sensor 52 becomes 0.5V or less or 4.5V or more (1 to 4V is the conventional output range, failure mode A-0).

When the small wheel further rebounds from the rebound state, the cylinder pressure sensor 52 detects the pressure increase and when.
When the output continues for more than m5ec (failure mode B-0)
).

When the heavy wheel further bumps from the bump state, the cylinder pressure sensor 52 detects a pressure drop of 300m5ec.
If -Fm are output continuously (failure mode B-0).

When the cylinder pressure sensor 52 continuously outputs an output signal of 30 kgf/cm2 or less for 300 m5ec or more with the heavy wheel bumping by 30 mmfu (failure mode B-0).

When the cylinder pressure sensor 52 continuously outputs an output signal of 100 kgf/cm2 or more for 300 m5ec or more with the wheel rebounding by 60 mm or more (failure mode B-0).

Within 0.3 seconds after the vehicle height of a certain wheel changes by 30 mm or more, the output signal of the cylinder pressure sensor 52 becomes 30 mm or more.
When the pressure is not the same as before the vehicle height change (
Failure mode A-1).

The output of the vehicle height sensor 51 (No. g or less than 0.5 V or 45
■When the power is on (1 to 4 V is the normal output range, failure mode A-0).

For 3 seconds after the lower G of a certain small wheel changes to O, ILu, the output signal of the vehicle height sensor of that wheel does not change (
Failure mode A-1).

When the output signal of the G sensor 53.63 is below 0.5V or above 4.5V for 1 second V'λF (1 to 4 is the normal output range, failure mode A-0).

The output of two or three lower G sensors 53 is 100m
When the output of other lower G sensors remains the same as the output from 100 m5 ec ago, even though the output is 5 ec@, or continues for more than 500 m5 ec (to failure mode -1).

The output value of the vehicle height sensor 51 is -degree rll for 10 minutes.
When the value is not within the range of ±2 mm (failure mode A-1).

When the state in which all the switching valves 9 are not in the same switching position continues for more than 1 second (failure mode AI).

When each switching valve 9 reaches the same switching position, but does not reach the commanded switching position within 10 seconds (failure mode A-1).

When the output of the lateral G sensor 63 is 0.5 V or less or 4.5 V or more (1 to 4 is the normal output range, failure mode A-0).

The output of the steering angle sensor 62 is 0.5V1. :, l below or 4
．． When it is above 5VVl (1 to 4v is the normal output range, failure mode A-0).

CP Ll error (failure mode bar ○).

Flowchart Now, referring to the flowchart shown in Figure 7,
A control example of the present invention will be explained. In addition, in Figure 7,
Only the parts unique to the present invention based on the pair of operating states of each cylinder device [t are shown, and in the following description, P indicates a step.

First, check whether the flag F is 1 in Pl and whether P
At P2, it is determined whether the flag F is 2 or not.
When this flag is set to 1, it indicates when a malfunction has occurred due to a difference in the operating status between cylinder devices, and when flag F is set to 2, it cancels the above-mentioned malfunction judgment and indicates that something has happened. Taste it.

When the determinations in Pl and P2 are both NO, the average pressure and average vehicle height are calculated for each cylinder device 1 in P3. Then, at P4, P3
The average pressure obtained in and the average vehicle height are compared or compared. Then, in P5, as a result of the comparison in P4 above, it is determined whether or not some of the average pressures or average vehicle heights are more stable than those of the messenger. be done. If the determination in P5 is No, it is assumed that the IF is normal and the process returns as is.

When the determination in P5 is YES, it is determined in P6 whether or not the vehicle is currently turning. With this P6 determination, N
In the case of O, after executing failure mode A control at Pl, wait for a predetermined time to elapse at P8 (wait for main pressure to be released), flag F is set to 1 at P9, and control is executed at P6. If the judgment is YES, the PI
At O, the maximum flow from the supply/discharge control valve 15.19 - QMAX, which indicates the suction regulation value, is set to a smaller value of 10 (see Table 1).
to continue the posture control. This PIO processing is done in consideration of the possibility that if attitude control is immediately stopped during a turn, the vehicle body may remain tilted when returning to a straight-ahead state. Attitude control is continued with a low control gain to avoid this. Therefore, instead of or in addition to Q MAX, the control gain of the ratio may be changed to a lower value.

After passing through P9, the PI's determination becomes YES.

At this time, the ignition switch is set to O at pH.
It is determined whether or not it has been turned FF. With this pH determination, No.
At this time, the supply/discharge control valves 15 and 19 are forcibly vibrated, that is, opened and closed repeatedly for a predetermined period of time (removal of clogged dirt).

In this case, the supply/discharge control valves to be vibrated may be targeted only to those that are determined to be abnormal, but it is preferable to vibrate all supply/discharge control valves to prevent dirt clogging. be.

If the pH determination is YES, flag F is set in PI3.
is set to 2, and the failure determination at P9 is canceled.

After passing through PI3, when the ignition switch is turned on again, the state shifts from P2 to PI4. In this PI4, attitude control is performed with Q MAX set to a low value such as 10 (see explanation of P I O). After this, processes P15 to P]7 are performed, which correspond to the processes P3 to P5 described above. Then, when PI7 determines that there is no abnormality, PI8
At , attitude control is performed with Q MAX restored to a normal value such as 15, and then at P]9 the flag F is reset to O.

When the determination in PI7 is YES, the above-mentioned processing from P6 onwards is performed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the overall circuit of an active suspension. FIG. 2 is a sectional view showing an example of the pilot valve in FIG. 1. FIG. 3 is a diagram showing a control system of the circuit shown in FIG. 1. FIGS. 4A and 4B are overall system diagrams showing an example of active control. FIG. 5 and FIG. 6 are diagrams showing examples of setting the usage area of each mode. FIG. 7 is a flowchart showing a control example of the present invention. IFR-IRL 15FR~1 5RL 19FR~l 9RL 51FR~51RL 52FR~52RL Two control units: Cylinder device: Liquid chamber, supply control valve: Discharge control valve: Vehicle height sensor: Pressure sensor

Claims (5)

[Claims] (1) It is a flow control type equipped with a cylinder device that is installed between the vehicle body and each wheel and adjusts the vehicle height according to the supply and discharge of hydraulic fluid, and a differential pressure valve, and the hydraulic fluid is supplied to the cylinder device. a supply/discharge control valve for supplying/discharging; an attitude control means for controlling the attitude of the vehicle body by outputting a flow control signal to the supply/discharge control valve based on predetermined conditions; and each cylinder device. A suspension device for a vehicle, comprising: failure determination means for determining whether or not a failure has occurred in which the attitude control is no longer performed normally by comparing the operating states of the suspension system. (2) According to claim 1, the operating state of each cylinder device is compared based on the internal pressure of the cylinder device or the vehicle height at a position corresponding to each cylinder device. (3) According to claim 1, when the failure determining means determines that a failure has occurred, the supply/discharge control valve is forcibly vibrated. (4) According to claim 1, when the ignition switch is turned off, the result of failure determination by the failure determination means is canceled. (5) In claim 4, when the ignition switch is turned on after the failure determination is once canceled, the attitude control is performed using a low control gain, and the result of the attitude control using the low control gain is When no failure is determined by the failure determination means, the attitude control is performed by returning to the normal control gain.