JPH02200510A - Suspension device for automobile - Google Patents

Abstract

PURPOSE:To improve stability of a car condition during a transitional period of a switching source of spring force and damping force in an active suspension by temporarily stopping suction and exhaust of operating liquid to a cylinder device. CONSTITUTION:By the operation of cut-off valves (9FR-9RL), communicating condition between a liquid chamber 5 of each cylinder device 1 and a cylindrical spring 7 that forms each gas spring 6FR-6RL is switched so as to control damping force. A control current is supplied to flow control valves 15FR-15RL, 19FR-19RL at the time, and each flow control valve 15FR-15RL, 19FR-19RL is so operated as to temporarily stop the supply of operating liquid to the cylinder device 1, according to a certain program. Car condition can thus be stabilized in a transitional period of changing the damping force.

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, so-called active suspensions have been proposed in which the suspension characteristics can be changed arbitrarily.Active suspensions basically consist of sprung weight and unsprung weight. A cylinder device is installed between them, 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.

In the above-mentioned active suspension, a vehicle height sensor that detects the vehicle height is basically 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 rh force values of a plurality of vehicle height sensors are changing but the output values of some of the vehicle height sensors do not change, A system has also been proposed in which it is determined that the vehicle height sensor in the vehicle is malfunctioning.

(Problems to be Solved by the Invention) In the above-described active suspension, a gas spring is generally connected to the liquid chamber of the cylinder device. In such devices, the spring force or spring constant can be changed by changing the capacity of the gas spring, or the damping force can be changed by changing the flow path resistance between the liquid chamber and the gas spring. It is considered possible to do so. For this purpose, a switching means for this switching is provided.

By the way, in a vehicle, it is undesirable for the spring force or damping force to differ between each wheel on the same floor. Therefore, in a vehicle where the spring force or damping force is variable as described above, the spring force between each wheel It is required that the forces or damping forces are all the same, that is, the switching positions of the switching means are all the same.

On the other hand, there is a slight difference in responsiveness between the switching operations of the above switching means, and as a result, during the transition period of changing the switching position, the magnitude of the spring force or damping force differs between each wheel. This can easily lead to problems such as. If hydraulic fluid is supplied to and discharged from the cylinder device during such a transitional period, differences in spring force or damping force will be promoted, which is undesirable from the standpoint of ensuring vehicle stability.

Therefore, an object of the present invention is to make the vehicle state more stable during the transition period of switching between the spring force and the damping force, assuming that at least one of the spring force and the damping force is variable in an active suspension vehicle. An object of the present invention is to provide a suspension device for a vehicle.

(Means and operations for solving the problem) In order to achieve the above-mentioned object, in the present invention, during a transition period when switching the spring force or damping force, the supply and discharge of hydraulic fluid to the cylinder device is temporarily stopped. I'm planning on suspending it. Specifically, the configuration is as follows. That is, a cylinder device is provided for each wheel and is installed between the sprung weight and the unsprung weight to change the vehicle height according to the supply and discharge of hydraulic fluid, and supply and discharge control means for controlling the supply and discharge of hydraulic fluid to and from the cylinder device; a gas spring provided for each wheel and communicating with the liquid chamber in the corresponding cylinder device; and a gas spring provided for each wheel and simultaneously with each other. a switching means that is switched to the same switching position to vary at least one of the capacity of the gas spring or the flow path resistance between the gas spring and the liquid chamber; and when the switching means is switched, and a suspension means for temporarily suspending the supply and discharge control of the hydraulic fluid by the supply and discharge control means.

This is a configuration with the following.

Preferably, the supply/discharge characteristics by the supply/discharge control means are changed according to switching of the spring force or the damping force (Claim 2). In other words, if we take into account that, for example, if the capacity of the gas spring is large, a larger amount of hydraulic fluid will be required to be supplied and discharged to obtain the same amount of vehicle height change than if the capacity is small. The benefits of doing so will naturally be understood. Furthermore, if you take into account that when the damping force is changed, even though the same flow rate of hydraulic fluid is supplied and discharged, the supply and discharge time will be different, which means that the response of the control will change. The advantages of having such a configuration will naturally be understood.

In addition, when each switching means cannot all be switched to the same required switching position, it is desirable to maintain the switching means in the state before this switching request. This causes the spring force or damping force to differ between each wheel.
This situation is prevented. Of course, at this time, it is preferable to maintain the control characteristics of the supply/discharge control at a value corresponding to the maintained switching position.

(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, rRJ is for the rear wheel, rFR'' is for the right front wheel, rFI, J is for the left front wheel, rRRJ is for the right rear wheel, and ``RL'' is for the right front wheel.
" means for the left rear wheel, and therefore, when there is no need to specifically distinguish between these, these identification codes will not be used in the explanation.

In the hydraulic fluid circuit diagram 1, 1 (IFR5IFL, IRR, IR
L) is a cylinder device provided for each front, rear, left, and right wheel, and these include a cylinder 2 connected to the unsprung weight, and a piston rod 3 extending from inside the cylinder 2 and connected to the unsprung weight. and has. 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 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 (
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 lO 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. 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.

A pump 11 in the figure is 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. In this right front passage 14FH, from the upstream side, a supply flow rate control valve 15FR1 and a pilot valve 16F as a delay valve are installed.
R is connected. 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. Further, the passage 14FR downstream of the pilot valve 16FR is connected to the first relief passage 17FH via the second relief passage 20FR, and a relief valve 21FR is connected to this.

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

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 accumulator 23F is provided to prevent the high-pressure hydraulic fluid in the front wheel cylinder device 1 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 wheel.

The common passage 13, that is, each passage 14F for the front and rear wheels,
14R is connected to a 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 relief 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 to 160 g/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 1 side. 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 16FH, and the other passage 3IF
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 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 moved to and from 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,
In other words, the pilot valve 16FR is biased in the closing direction. Furthermore, the control piston 38 has a communication port 42.
The pressure of the main flow channel 34 is applied on the side opposite 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 the pressure on the 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 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 relief valve 21 is normally closed and the cylinder device 1
When the pressure on the side is above a specified value (160 to 200 kg in the example)
/cm2), it is opened.

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

Of course, the relief valve 21 is a cylinder device IRR for the rear wheels.
, can also be provided for the IRL, but in the example, it is assumed that the vehicle has two weight distributions where the front side is set much larger than 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 greater than the pressure.

(2) 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 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 32H. 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.

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 has each sensor 51F.
R~51RL, 52FR~52RL, 53FR253F
Signals from L, 53R, and 61 to 63 are input, and limit switches 73 (73F
73FL), and in addition, ON and OFF signals from the ignition switch 71 are input. Further, from the control unit U, the switching valve 9, the flow rate control valves 15 (15FR-15RL), 19 (19FR
-19RL), is output to the control valve 26 and alarm device 72 such as an alarm lamp or buzzer.

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 detects the 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). It detects the lateral G acting on the vehicle body (in the embodiment, only one is provided on the Z axis of the vehicle body).

The control unit U basically performs active control conceptually shown in FIG. 4, that is, in the embodiment, vehicle attitude control (vehicle height signal control), ride comfort control (vertical acceleration signal control), and vehicle control. torsion control (pressure signal control).

The results of each of these 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.

Active Control Next, an example of how to control the suspension characteristics based on the outputs of each sensor will be described with reference to FIGS. 4 and 5.

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 control) This control consists of three attitude controls that suppress bounce, pitch, and roll.
Feedback control is performed using FD amount control (proportional - thorough control m).

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 at this time is This is shown in the following equation (1).

KB1+ (Ta2- S/ (1+TB2 S))
・KH2・ ・Fist (1) KBI, KH2) Ta2: Control gain (constant) S
:Operator In addition, in the pitch control, FD sub-control is performed in a direction in which the sum of the added values of the left and right rear vehicle heights is subtracted from the added value of the left and right front vehicle heights to zero. 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, and is added to each other for each control value for each cylinder device 1. Finally, the control values for the four attitude control is determined as the flow rate signal QXFR-QXRL.

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). .

■G ride comfort control w (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 attitude controls mentioned above, bounce, pitch, and roll are each controlled using IPD control (integral-proportional one-to-one system) to suppress the acceleration in the downhill direction. The control equation based on this IPD control is shown in the following equation (2).

(TB3/ (1+TB3-S)) ・KB3+K
B4+(Ta3- S/ (1+TB3・5))-KB
3- ・ ・ (2) KH2, KH2, TBG: 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 mean of the front left and right vertical accelerations is used as the front vertical acceleration for pitch 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, each control value obtained by the three IPD 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 1, and finally Four flow signals Q for ride comfort control
GFR-QGRL.

■Warp control (pressure signal control) Warp control is a control that suppresses torsion of the vehicle body B. That is, 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 weighting is such that the amount of torsion on the front side and the rear side of the vehicle body is weighted by the coefficient ωF, and the weighting is applied to each of the controls (1) and (2) by the coefficient ωA. Of course, also in this twist suppression control, the control value is finally determined as the flow rate signal QPFR-QPRL (%) for each of the four cylinder devices 1.

The flow rate signals for attitude control, 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 rate signal QF.
It is determined as R-QRL.

(Left below) ②The control gain of the control formula used in the explanation of FIG. 4 above is switched and controlled by a control system as shown in FIG.

First, the steering angle speed θX and the vehicle speed V were multiplied, and the reference value G1 was calculated from the result θX・V (ff
Input St to the turning determination section. Further, a value S2 obtained by subtracting the reference value G2 from the current lateral acceleration GS of the vehicle is input to the turning determination section. Then, in the case of input S1 or S2≧0, the turning determination unit determines that the vehicle is turning, outputs a suspension characteristic hardening signal Sa, and follows the flow rate control for each hydraulic cylinder 3. In order to improve the performance, the damping force switching valve 10 is switched to the throttle position, and each proportionality constant Ki (i=B l-84) is set to a large value KH.
ard, and from a map in which each target roll T ROLL is stored in advance, a value corresponding to the lateral acceleration Gs at that time is set. An example of this map is shown in FIG. Incidentally, in the case of a puffy suspension vehicle, as shown in FIG. 7, the roll angle (positive roll) increases as the lateral G increases.

On the other hand, if the inputs S1 and s2<o in the turning determination section,
It is determined that the vehicle is traveling straight, outputs a suspension characteristic softening signal sb, switches the damping force switching valve 10 to the opening position, sets each proportionality constant Ki to the normal value Ksoft, and sets the target roll angle TR0LL=O. Set to .

FIG. 8 shows the relationship between the target stroke and flow rate in the hard and soft conditions.

Flowchart Now, referring to FIGS. 9A and 9B, the switching valves 9 (9FR to 9FL) as switching means between spring force and damping force will be described.
) control when switching will be explained. Note that in the following explanation, S indicates a step.

First, at Sl in FIG. 9A, it is determined whether the flag F is 1 or not. When this flag F is 1, it indicates an abnormal situation in which switching of the switching valve 9 was not performed normally, but as will be described later, this flag F is initialized to 0 when the ignition switch is OFF. ,-unless a failure (abnormality) of the switching valve 9 is detected, this flag F
is left as O.

When the determination of SL is NO, in S2, it is determined whether or not it is time to start turning, that is, as explained in FIG.
It is determined whether or not a turn that causes the switching valve 9 to harden has started. When the determination in S2 is YES, active control is suspended in S3. Thereafter, in S4, a signal is output to each switching valve 9 to set it to a hard switching position. Then, in S5 after S4, it is determined whether all the switching valves 9 have reached the hard switching position or not, but this determination in S5 is actually performed one second after the output of 84. YES in this S5 determination
In this case, active control is performed again in S6. In addition, in the active control at this time, the control gain is set for the hardware in accordance with the switching position of the hardware (see FIGS. 5 and 8).

When the determination in S5 is No, it is determined in 511 whether all the switching valves 9 are in the soft switching position. If the determination of Sll is YES, the timer is counted down in S12, and the timer is counted down to 1 in the process of S13.
Wait for 0 seconds to count. Then, when the determination in S13 is YES, that is, when 10 seconds have been counted, the alarm 72 is activated in S14, assuming that an abnormality has occurred in which all the switching valves 9 have not reached the hard switching positions. After this, active control is performed again (the control gain is soft), and the flag F
is set to 1. Note that the reason for waiting for 10 seconds in S13 is to confirm that all switching valves 9 are stably at the soft switching positions.

Said 511(7) Discrimination TeNO(7),! l"kiha,
321. After waiting for one second to pass through the process in S22, a signal indicating the soft switching position is output to all switching valves 9 in S23. Thereafter, in S24, it is determined whether all the switching valves 9 have become soft or not, but in reality, the determination in S24 is performed after one second has elapsed after the output in S23. If the determination in S24 is YES,
The alarm 72 is activated in S25, active control is activated (control gain is soft) in S26, and flag F is set to 1 in S27.

If the determination in S24 is NO, all the switching valves 9 cannot be set to the same switching position, that is, /\- or soft switching position, that is, some switching valves 9 are in the soft switching position. This is when the remaining switching valves 9 are in the hard switching position. At this time, the vehicle is likely to become unstable, so at 328, the active control is immediately stopped, the relief control valve 26 is opened to release the pressure in the accumulator 22, and the alarm 72 is activated. Activate. Then, in S29, flag F is set to 1.

When the determination in S2 is No, it is time to set the switching valve 9 to the soft switching position. In this case, 3 in Figure 9B
31, it is determined whether or not the current/\-mode switching position is reached. If the determination in S31 is NO, the process returns as it is not necessary to change the switching position. Also, if the determination in S31 is YES, S32) S
After waiting for 4 seconds to elapse through the process in step 33, the active control is paused in step S34. After this, S35
After outputting to all the switching valves 9 so that they are in the soft switching position, it is determined in S26 whether all the switching valves 9 have reached the software switching position, but this determination is actually This is performed after one second has elapsed after the output of S35. If the determination in S36 is YES, active control is performed in S37 (the control gain is soft).
.

If the determination in step 336 is NO, steps 2841 to S59 are performed, which correspond to steps S11 to S29 in FIG. 9A. That is, S41 to S46 are S4
1 to S46, and 521-327 corresponds to S51 to S57.
, and S28 and S29 correspond to S58 and S59. The only difference between these S11-329 and S41-S59 is that one should originally have a hard switching position, while the other should originally have a soft switching position, so the overlap Explanation will be omitted.

On the other hand, if the determination in step 51 in FIG. 9A is YES, then in step 9B,
Move to 361 in the figure and turn the ignition switch 71 to O.
It is determined whether or not it is the time of FF. This S61
If the determination is No, the process returns as is, and S6
If the determination in step 1 is YES, the flag F is reset to O in 362. Through the process of S62, after the ignition switch is turned on again, active control is performed unless poor control of the switching valve 9 occurs again.

Although the embodiments have been described above, only either the spring force or the damping force may be switchable. Further, this switching command may be issued using a manual switch.

(Effects of the Invention) As is clear from the above description, the present invention is advantageous in ensuring the stability of the vehicle during the transition period of switching between spring force or damping force in a system that actively controls a suspension.

Moreover, by adopting the configuration as set forth in claim 2, active control can always be made appropriate in response to changes in spring force or damping force.

Furthermore, by adopting the configuration as set forth in claim 3, active control can be prevented from being canceled unnecessarily.
Opportunities for performing this active control can be expanded.

[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. FIG. 3 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 the correspondence between the hard and soft switching positions and control characteristics of the switching valve. FIGS. 9A and 9B are flowcharts showing control examples of the present invention. IFRN IRL 9FR~9RL 15FR~ 15RL 19FR~ 1 9RL: Control unit Nijilinda device: Liquid chamber: Gas spring nitrogen orifice; Switching valve nitrogen orifice: Supply control valve: Discharge control valve Patent applicant: Nardec Co., Ltd. Figure 6 Figure 7 Zu Maki G Ej = Danguchi〈Uwo Redemption J1 (i Ryo Kiyoh)) and Talk Crew Xiputei轡)

Claims (3)

[Claims] (1) A cylinder device provided for each wheel and installed between the sprung weight and the unsprung weight to change the vehicle height according to the supply and discharge of hydraulic fluid; supply and discharge control means for controlling the supply and discharge of hydraulic fluid to and from each cylinder device; a gas spring provided for each wheel and communicating with the liquid chamber in the corresponding cylinder device; and a gas spring provided for each wheel and mutually connected to each other. a switching means that is switched to the same switching position at the same time to vary at least one of the capacity of the gas spring or the flow path resistance between the gas spring and the liquid chamber, and when the switching means is switched; A suspension device for a vehicle, comprising: a suspension means for temporarily suspending supply and discharge control of hydraulic fluid by the supply and discharge control means. (2) Claim 1, further comprising control characteristic changing means for changing the supply/discharge amount of the hydraulic fluid controlled by the supply/discharge control means in response to a change in the switching position of the switching means. What you have. (3) In claim 2, further comprising a switch-unable detection means for detecting that each of the switching means cannot be switched to the required switching position in the same manner, and a switch-unable state detected by the switch-unable detecting means. When detected, all of the switching means are held at the switching positions before the switching request with priority over the requested switching position, and the control characteristics of the supply/discharge control means are changed to correspond to the held switching positions. The device further comprises a failure control means for causing the device to hold the device.