JPH0459419A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To ensure the operation of feed and discharge control valves by forcedly operating the feed control valve and discharge control valve for operating fluid to a cylinder device in a determined state so that the feed quantity and the discharge quantity are equalized, and controlling a measure to refuse clogging. CONSTITUTION:In the control of a measure to refuse clogging, feed control valves 15FR-15RL and discharge control valves 19FR-19RL are opened so that operating fluid simultaneously flows therein in the same quantity. The flow rate at this time is preferably a maximum flow rate. This control is conducted only for a preset determined time, and the opening and closing of the feed and discharge control valves 15FR-15RL, 19FR-19RL are repeated within this time. The control of the measure to refuse clogging is performed only once just after ON every ON of an ignition switch. According to this constitution, an operation failure by refuse clogging can be prevented.

Description

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

(Prior art) A vehicle suspension, which is called a passive suspension, has a damper unit consisting of a hydraulic shock absorber and a spring (generally a coil spring), and the suspension adjusts according to preset characteristics of the damper unit. Characteristics are 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, so-called active suspensions have been proposed in which the suspension characteristics can be changed arbitrarily. A cylinder device is installed in the cylinder, and the suspension characteristics are changed by controlling the supply and discharge of working fluid to the cylinder device (see Japanese Patent Laid-Open No. 130418/1983).

In this active suspension, by supplying and discharging working fluid from the outside, suspension characteristics can be significantly changed for various attitude controls such as vehicle height control, roll control, and pitch control. In order to supply and discharge working fluid to and from the cylinder device, a supply and discharge control valve, that is, a supply control valve and a discharge control valve, are provided.

(Problems to be Solved by the Invention) In the active suspension device as described above, there is a possibility that the supply/discharge control valve may not operate normally, that is, it may become inoperable due to clogging with dirt, etc., and in this case, the posture Control will not be performed properly. In particular, if the supply/discharge control valve is not operated for a long period of time, there is a high possibility that such an inoperable situation will occur.

Therefore, an object of the present invention is to provide a suspension device for a vehicle in which the supply/discharge control valve can always be operated reliably.

(Structure, operation, and effect of the invention) In order to achieve the above object, the present invention has the following structure. That is, 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 working fluid, a supply control valve that supplies working fluid to the cylinder device, and a cylinder device that controls the vehicle height from the cylinder device. a discharge control valve for discharging the working fluid; a first m11m means for controlling the attitude of the vehicle body by controlling the supply control valve and the discharge control valve based on predetermined conditions; A configuration comprising a second control means for controlling the supply control valve and the discharge control valve so that the same amount of working fluid is supplied from the control valve and the same amount of working fluid is discharged from the discharge control valve. It's Toshide.

As described above, in the present invention, by actively operating both the supply control valve and the discharge control valve when a predetermined state is reached, it is possible to effectively prevent or prevent the inoperable state due to clogging with dirt or the like. It is possible to remove any garbage that may be present.

In a predetermined state in which the supply/discharge control valve is operated to take measures against this dust, the amount of working fluid supplied to the cylinder device and the amount of discharged are the same, which may cause a change in vehicle height. do not have.

When forcibly operating the supply/exhaust control valve to prevent the above-mentioned jamming, the predetermined state is when there is no problem in controlling the attitude of the vehicle, such as when the vehicle is stopped or the ignition switch is turned on. It may be done immediately after.

(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, rRLJ
means 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, 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 above by a piston 4 integrated with a piston rod 3, and this liquid chamber 5 and a lower chamber are in communication. As a result, when the hydraulic fluid is supplied to the liquid chamber 5, the piston rod 3 extends and the vehicle height becomes high, and when the hydraulic fluid is discharged from the liquid chamber 5, the vehicle height becomes low.

For the liquid chamber 5 of each cylinder device l, a gas spring 6 (
6FR16FL, 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 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, 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. This front right passage 14FR is connected to the liquid chamber 5 of the cylinder device IFR for the front right wheel, and the front left passage 14FL is connected to the liquid chamber 5 of the cylinder device IFL for the front left wheel. A pilot valve 16FR serving as a supply flow rate control valve 15FR1 and a delay valve is connected to this front right passage 14FR from its upstream side. Similarly, from the upstream side of the left front passage 14FL, a supply flow rate control valve 15FL, a pipe 1
~Valve 16FL is connected.

A first relief passage 17FR for the right front passage is connected to the front right passage 14FR 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 17FR. Moreover, the passage 14FR downstream of the pilot valve 16FR is connected to the first relief passage 17FR via the second relief passage 20FR, and the relief valve 21FR is connected to this. Furthermore, a filter 29FR is interposed in the passage 14FR closest to the cylinder device IFR. This filter 29FR
is the valve 1 located closest to the cylinder device IFR.
Located between 6FR121FR and the cylinder device IFR
Abrasion powder generated from the valve 16 due to sliding etc.
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 leaf 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 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 supply/discharge passage for the rear wheel cylinder device IRR1IRL is 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 valve 21FR121FL 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 wheels.

The common passage 13, that is, each passage 14F for the front and 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 leaf passage 25.

In FIG. 1, 27 is a filter, and 28 is a pressure regulating valve for adjusting the discharge pressure from the pump 11 to be within a predetermined range.
is configured as a variable displacement swash plate piston type and is integrated into the pump 11 (discharge pressure 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 14R5, that is, the common passage 13, and the pressure in one example of the cylinder device. Therefore, for the pilot valve 16FR116FL for the front wheels, a common pilot passage 31F branched from the passage 14F is led out, and a two-way branched from the common pilot passage 31F is led out.
One of the branch pilot passages 31FR is connected to the pilot valve 16FR, and the other passage 3IFL is connected to the pilot valve 16FR.
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 14FR 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 seated on and off the valve seat 35, so that 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 16FR 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).

Next, the effect of the above-mentioned answer 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 2I Relief valve 2■ is normally closed, and cylinder device 1
side pressure is above a predetermined value (160 to 200 k in the example)
g/cm2), it opens.

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 2I is a cylinder device IRR for the rear wheels.
Although it can also be provided for 1 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, so that the pressure on the rear wheel side is equal to the pressure on the front wheel side. The relief valve 21 is not provided on the rear wheel side in consideration of the fact that it does not become larger than the above.

■Flow rate control valve work 5.19 Both the supply and discharge flow rate control valves 15.19 are electromagnetic spool valves that can be switched between open and closed states as appropriate. However, when it is open, it has a differential pressure adjustment function that keeps the differential pressure between the upstream and downstream sides almost constant (due to flow rate control, this differential pressure must be kept constant). ). More specifically, the displacement position or opening degree of the spool of the flow control valve 15.19 is changed in proportion to the supplied current, and this supplied current is determined based on a flow rate-current correspondence map created and stored in advance. Determined based on 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 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).
.

■Control Valve 26 The control valve 26 is normally closed by being energized, and is opened in the event of a failure. This failure can occur, for example, when part of the flow control valve 15 or 19 becomes stuck, when the sensors described below fail, when the hydraulic pressure of the hydraulic fluid fails, or when 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, 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 control valve 15 remains open, the pilot pressure decreases due to the opening operation of the control valve 26, resulting in passages 14FR to 14R.
L is closed to confine the hydraulic fluid in the cylinder devices IFR to IRL, and the vehicle height is maintained. Of course, at this time,
The suspension characteristics are fixed to so-called passive characteristics.

FIG. 3 shows the control system of the hydraulic fluid circuit shown in FIG. 1.

In FIG. 3, WFR is the left 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 51R.
L, 52FR~52RL, 53FR153FL, 53R
and 61 to 64, and from the control unit U, the switching valve 9, the flow control valve 15 (15F
R-15RL), 19 (19FR to 19RL) 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-IRL (see also FIG. 1). sensor 5
3FR153FL and 53R are G sensors that detect acceleration in the vertical direction. However, on the front side of vehicle B, two G sensors 53FR1 are installed at almost left-symmetric positions on the front axle.
53FL, but at the rear of the vehicle B, only one G sensor 53R is provided at the middle position between the left and right sides on the rear axle. 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 two axes of the vehicle body). switch 64
is for changing control characteristics, and this point will be described later.

The control unit U basically performs active control conceptually shown in FIGS. 4A and 4B, that is, in the embodiment, the vehicle attitude side? II (vehicle height signal control and vehicle height displacement speed basis @), ride comfort control 'l (vertical acceleration signal control), and vehicle torsion control (pressure signal control). and,
The results of each of these separate controls are finally expressed as the flow rate of the hydraulic fluid flowing through the flow rate control valve 15, 19 serving as the flow rate adjusting 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, which control the attitude of the vehicle body B based on the output of the most basic vehicle height sensor and its differential value (vehicle height displacement speed);
Control system x3 that performs ride comfort control based on sensor output
, 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 control system X5 based on the output of the lateral G sensor 63, which are divided as follows.

■Control XI (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 III control C proportional control). be done.

First, reference numeral 70 is the sum of the outputs XFR and XFL of the left and right front wheels among the vehicle height sensors 51FR to 51RL, and the output XRR of the left and right rear wheels.

This is a bounce component calculation unit that calculates the bounce component of the vehicle by summing XR1, . Reference numeral 71 denotes a pitch component calculation unit that calculates the pitch component of the vehicle by subtracting the total value of the outputs XRR and XRL of the left and right rear wheels from the total value of the outputs XFR and XFL of the left and right front wheels. Reference numeral 72 denotes a roll component calculation unit that calculates the roll component of the vehicle by adding the difference XFR-XFL between the outputs of the left and right front wheels and the difference XRR-XRL between the outputs of the left and right rear wheels. .

Reference numeral 73 receives the vehicle bounce component calculated by the bounce component calculation unit 70 and the target vehicle height signal TH from the target average vehicle height determination unit 91, and calculates the bounce control based on the gain coefficient. This is a bounce control unit that calculates the control amount for the flow control valve of each wheel. Reference numeral 74 indicates that the pitch component of the vehicle calculated by the pitch component calculating section 71 and the target pitch amount Tp from the target pitch amount determining section 92 are manually input, and the vehicle corresponding to the target pitch amount Tp is calculated based on the gain coefficient 1KPI. This is a pitch control unit that calculates the control amount of each flow rate control valve in pitch control so that the flow rate is high. code 7
5 is the vehicle roll component calculated by the roll component calculation section 72 and the target roll H from the target roll amount determination section 93.
TR is input, gain coefficients KRFI, KRRI
Based on this, the vehicle height corresponds to the target roll amount TR. This is a roll control pusher that calculates the control amount of each flow control valve in roll control.

Then, the vehicle height should be controlled to the target vehicle height (the respective control units 7
3.74.75, the positive and negative values of each control weight are reversed for each wheel (inverted so that the positive and negative values are opposite to the positive and negative values of the vehicle height displacement signals of the vehicle height sensors 51FR to 51RL), and then, The bounce, pitch, and roll control amounts for each wheel are added, and in the control system x1, the flow signals of the corresponding proportional flow control valves QFRI, , QFLl, QR
RI and QRLI are obtained.

Here, the target vehicle height TH can be kept at a certain constant value, such as 150 mm in terms of the minimum ground clearance of the vehicle. It is also possible to change the target vehicle height TH. In this case, for example, TH can be changed stepwise or continuously in accordance with the vehicle height (for example, when the vehicle speed is 80 km/h or more). (minimum ground clearance is set to 130mm).

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

■Control system X2 (vehicle height displacement speed component) In the control system x2, pitch control and roll control are performed.

First, the pitch component from the pitch component calculation section 71 and the target pitch iTP 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 change rate from the vehicle height sensors 51FR to 51RL. The amount of change for each signal sampling time (10 m5ec in the example) is determined.

Then, the control gain KP2 is used for 5 seconds to determine the controlled flow rate i for each flow rate control valve so that the rate of change in the direction of increasing the pitch amount is small.

Further, the roll amount (roll angle) from the roll amount calculation section 72 and the target roll HTR from the target roll amount determining means are input to the roll control section 79. This roll control unit 79 controls each set of left and right front wheels and left and right rear wheels.
The control flow rate for each flow rate control valve is determined using the control gain K RF2 or K RR2 so that the rate of change in the actual roll amount in the direction away from the target roll @TR becomes small.

The control amounts determined by each of the control units 78 and 79 are reversed in sign and then added for each flow control valve (each cylinder device IFR to IRL) to obtain the control flow rate Q FR2QFL2 in the control system x2. , QRR2) QRL
2 is determined. Note that "S" shown in each control unit 78 and 79 is an operator showing differentiation.

■Control system X3 (vertical acceleration component) First, reference numeral 80 indicates three vertical acceleration sensors 53FR1.
Outputs GFR and GFL of 53FL 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 amount for the flow rate control valve of each 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 indicates that the roll component of the vehicle calculated by the roll component calculation unit 82 is manually added to a gain coefficient KRF3.
, KRR3 is a roll control unit that calculates the control amount of each flow control valve in roll control.

In order to suppress the vertical vibration of the vehicle with a bounce component, a pitch component, and a roll component, each control amount calculated by each of the control units 83 to 85 is reversed for each wheel, and then, for each wheel. The bounce, pitch, and roll control amounts are added, and in the control system X3, the flow signals QFR3, QFl, 3,
QRR3 and QRL3 are obtained.

(1) 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 signals PFR, PFL of the two front wheel side hydraulic pressure sensors 52FR552FL.
is input, and the total hydraulic pressure on the front wheel side (P FR + P F
Ratio of left and right fluid pressure difference (PFR-PFL) to L) (
Calculate PFR-PFL)/(PFR+PFL). Further, the rear wheel side hydraulic pressure ratio calculating section 90b calculates the same hydraulic pressure ratio (PRR-PRL) / (PRR+PRL) on the rear wheel side.
Calculate.

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 for each wheel is equalized between the left and right wheels (reversed, and in the control system x4,
Flow rate signals of the corresponding flow control valves QFR4, QFL4,
QRR4 and QRL4 are obtained.

■Control System X5 (Lateral G Component) Control detection x5 is performed based on a signal from the lateral G sensor 63 to suppress an increase in lateral G acting on the vehicle body and to reduce roll vibration. In this control system x5, the signal obtained by the control section 100 based on the control gain KG is
The sign is reversed for the left wheel and the left wheel, and the flow signal QFJ (5, QFL5, QRR5) of the corresponding flow control valve is
, QRL5 is obtained. Then, the control ratio between the front side and the rear side is changed by the coefficient AGF.

■Synthesis of each separate control system
, QRLI, vehicle height displacement speed component Q FR2QFL2
, QRR2) QRL2 , vertical acceleration component QFR3
, QFL3, QRR3, QRL3, pressure component QF
R4, QFL4, QRR4, QRL4, lateral G component QFR5゜QFL5, QRR5, QRL5 are finally added to form the final total flow signal QFR, QF
L, QRR, and QRL are obtained.

Specific examples of settings for the control gains, etc. used in FIGS. 4A and 4B are shown in Table 1 below.

Table 1 In Table 1, the meanings of the symbols not shown in FIGS. 4A and 4B are as follows. First, XI (corresponds to the vehicle height signal and is used to set its dead zone. GG corresponds to each vertical and lateral G sensor and is used to set its dead zone. Q MAX corresponds to the maximum flow rate for inflow and outflow. P MAX is for limit setting of inflow pressure, and P MIN is for limit setting of discharge pressure.

Furthermore, in Table 1, modes 1 to 7 are set, and the setting characteristics 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 changes in vehicle height 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.
Mode 3 is a setting that emphasizes ride comfort, Mode 4 is for setting reverse roll, Mode 5 is a setting that aims to balance ride comfort and steering stability, and Modero is a setting that aims to balance ride comfort and posture maintenance. Mode 7 is a setting that emphasizes steering stability. The setting of the usage area for these modes 3 to 7 is based on the vehicle speed and lateral G as shown in Figure 5 or Figure 6.
The switching between the modes shown in FIG. 5 and FIG. 6 is performed using a separately provided manual switch 64 for mode switching (see FIG. 3).

Mode 3, mode 5, mode 6, and mode 7 correspond to any of the first control characteristic to third control characteristic in the present invention. That is, among these modes, mode 3
provides the best riding comfort and corresponds to the first control characteristic. Furthermore, mode 7 places the greatest emphasis on stability and corresponds to the third control characteristic. Mode 5, Mordoro, takes into account both ride comfort and stability, and corresponds to the second control characteristic, and selection between modes 5 and 6 is switched by lateral acceleration. In other words, Mode 5 places more emphasis on ride comfort than Mode 6 (Mode 6 puts more emphasis on stability than Mode 5), and when the lateral G is small. Mode 5 is selected when the lateral G is large, and Moto 6 is selected when the lateral G is large. Note that the target vehicle height TH is changed according to the vehicle speed based on a predetermined reference vehicle height (e.g., equivalent to 160 mm in minimum ground clearance), and the target roll vehicle height TR is changed using the lateral G as a parameter.

When changing modes between modes 1 and 7, there is no delay when changing to a higher mode, such as when changing from mode 3 to mode 5 or mode 6. , when transitioning to a low mode, for example, when transitioning from mode 7 to mode 5 or mode 3, the modes are successively decreased one by one, and a predetermined delay time is set each time one mode decreases. 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.

Next, with reference to the flowchart of FIG. 7, the control for preventing the supply/discharge control valves 15 and 19 from becoming inoperable due to clogging with dirt will be explained. Note that in the following explanation, P indicates a step.

In FIG. 7, control is performed to prevent dust clogging immediately after the ignition switch is turned on. First, it starts when the ignition switch is turned on, and the PI
In the step, it is determined whether the flag F is 1 or not. This flag F is set to 1 when a dust clogging countermeasure is taken when it is 1, and is reset to O at the time of shipment from the factory.

When the determination of Pl is No, the supply control valve 15 and the discharge control valve 19 are forcibly opened at the same time in P2 so that the same flow rate flows. It is preferable to set the flow rate at this time to the maximum flow rate in order to prevent dust clogging or remove dust. Note that this control of Pl2 is performed only for a preset predetermined time, but it is preferable to repeatedly open and close the supply/discharge control valve 15.19 within the predetermined time. After P2, the flag F is set to 1 in P3 and the process returns.

P2) After passing through P3, the determination of Pl is YES.
At this time, the process moves to P4. At P4, it is determined whether the ignition switch is turned off. This P4
If the determination is NO, the process returns as is. Then, when the determination at P4 is YES, the flag F is reset to O at P5.

In this way, each time the ignition switch is turned on, the dust clogging countermeasure control (P2) is performed only once immediately after the ignition switch is turned on.

In FIG. 8, control is performed to prevent dirt clogging every time the vehicle stops. First, it is determined at Pl whether the flag is 1 or not, and when the determination at Pll is NO, it is determined at Pl2 whether or not the vehicle speed V is zero. When the determination of Pl2 is YES, Pl3 and Pl4
This corresponds to the processes P2 and P3 in FIG. 7.

If NO in tIj of P]2 above, the process returns as is.

After passing through PI3 and PI4, the pH determination becomes YES. At this time, in PI5, it is determined whether the vehicle speed ■ is zero or not. If PI5 is YES, it means that the vehicle has not been driven since the garbage clogging countermeasure control (PI3) was performed, and the vehicle is returned. If the PI5 determines No, the next time the vehicle is stopped, control will be carried out to prevent garbage from clogging.
The flag is reset to O in PI6.

[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 a device for performing active control. Figures 5 and 6 are examples of setting the usage area for each mode.
Sheep Sai/i)/'J子i) βtsu purchase no transfer rga/wozunoσ-chi→-A. IFR~IRL Nijilinda device 15FR-15RL: Supply control valve 19FR~19RL: Discharge control valve port: Control unit Fig. 5 High speed (krn/h> Fig. 6 Heavy speed (km/h)

Claims (3)

[Claims] (1) A cylinder device that is installed between the vehicle body and each wheel and that adjusts the vehicle height according to the supply and discharge of working fluid, a supply control valve that supplies working fluid to the cylinder device, and the cylinder device a discharge control valve for discharging working fluid from the exhaust control valve; a first control means for controlling the attitude of the vehicle body by controlling the supply control valve and the discharge control valve based on predetermined conditions; and in a predetermined state, a second control means for controlling the supply control valve and the discharge control valve so that the same amount of working fluid is supplied from the supply control valve and the same amount of working fluid is discharged from the discharge control valve; A vehicle suspension device comprising: (2) In claim 1, The predetermined state is when the vehicle is stopped. (3) Claim 1, wherein the predetermined state is immediately after an ignition switch is turned on.