JPH06122309A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To calculate the setting change of many control gains in a short time without making a high-speed calculation by controlling the feed/discharge quantities of an operating fluid to fluid cylinder devices between the spring upper and lower weights of wheels with the fuzzy logic based on the detected quantities of the movement of a vehicle or the road surface state. CONSTITUTION:Gas springs 5 and proportional control valves 9 are provided between fluid cylinder devices 3 provided between a car body 1 and wheels 2FL, 2RL, and a hydraulic pump 8, and they are controlled by a control unit 17. The control unit 17 is inputted with signals of sensors 18, 19, 101-112 on the steering angle, vehicle speed, yaw rate, brake, and oil pressure as movement state of the vehicle 1 and signals on the roughness and undulation of the road surface as the road surface state. The control unit 17 changes the control gains of parameters on the running state with the fuzzy logic and determines the feed quantity and discharge quantity of the operating fluid to the fluid cylinder devices 3. The control unit 17 can change the setting of many control gains in a short time without using a high-speed calculating means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension system for a vehicle, and more particularly to an active suspension system capable of changing suspension characteristics as desired.

[0002]

2. Description of the Related Art Conventionally, a suspension device called a passive suspension is composed of a hydraulic shock absorber and a damper unit composed of a spring (for example, a coil spring). By varying the damping force of the hydraulic shock absorber, Although the suspension characteristics can be changed to some extent, the range is small, and the suspension characteristics of the passive suspension device are substantially set uniformly.

On the other hand, in recent years, a suspension characteristic is desired by providing a fluid cylinder device between the sprung weight and the unsprung weight and controlling the supply amount and the discharge amount of the working fluid with respect to the fluid cylinder device. A suspension device called "active suspension" that can be modified as follows has been proposed (for example,
JP-B-59-14365 and JP-A-63-1304
No. 18, etc.).

There are three types of vehicle vibrations, bounce, pitch, and roll, and such an active suspension device detects at least vehicle height displacement detection means and vertical direction applied to the vehicle. A vertical acceleration detecting means for detecting acceleration is provided, and the driving state of the vehicle is detected based on the values detected by these detecting means. In order to improve the supply amount or discharge amount of the working fluid to the fluid cylinder device of each wheel, the opening degree of the flow control valve of each wheel is set with a predetermined control gain that is set and controlled according to the operating state of the vehicle. It is controlled by controlling.

[0005]

In this case, the suspension characteristic can be made closer to an ideal one as the number of parameters relating to the traveling state of the vehicle for which the control gain is set and controlled is increased. That is, it is possible to obtain suspension characteristics that achieve both steering stability and riding comfort.

However, since it is necessary to set or change the control gain instantaneously, the higher the number of parameters relating to the running state of the vehicle for which the control gain is set and controlled, the faster the calculation becomes. . If a high-speed computer is installed in a vehicle, high-speed calculation can be performed, but it is difficult to install a relatively large high-speed computer because the space in the engine room is limited. if,
Mounting a high speed computer is not practical. For this reason,
It is necessary to perform high-speed calculation without using a high-speed computer, but this requires a considerable amount of time. Therefore, if the number of parameters relating to the traveling state of the vehicle, which is the target of the control gain, is increased, there arises a problem that the control of the suspension device cannot catch up with time.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a supply amount of a working fluid to a fluid cylinder device provided between an unsprung weight and an unsprung weight of each wheel. In a vehicle suspension device capable of changing suspension characteristics by controlling an emission amount, a large number of control gain setting changes can be calculated in a short time without performing high-speed calculation using a means such as a high-speed computer. It is an object of the present invention to provide a suspension device for a vehicle that can do the above.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a motion condition detecting means for detecting a plurality of motion conditions or road conditions of a vehicle,
This can be achieved by including control means for determining the supply amount and the discharge amount of the working fluid by fuzzy logic based on the amount of the motion state or the road surface state detected by the motion state detecting means.

In a preferred embodiment of the present invention, the control means changes the control gain of a parameter relating to the running state of the vehicle by fuzzy logic based on the amount of the motion state or the road surface state detected by the motion state detecting means. , Determine the supply and discharge of working fluid.
In a further preferred aspect of the present invention, at least one of the vehicle height displacement, the vehicle height displacement speed, the vertical acceleration, the torsion, the lateral acceleration, and the pressure in the cylinder device is selected as the parameter.

In a further preferred embodiment of the present invention, road surface conditions include road surface roughness and road undulation, and motion conditions include vehicle speed, vehicle lateral acceleration, accelerator opening speed, vehicle longitudinal acceleration, and shift. Whether there is a change, the steering angular velocity of the vehicle, the yaw rate of the vehicle, whether the braking device is operating, whether the anti-brake skid device is operating,
At least one of the following: whether the traction control device is operating, the degree of in-phase of the four wheels when the four-wheel steering device is operating, engine speed, system pressure, favorite slide switch mode, road friction coefficient and oil temperature. To be elected.

[0011]

In the present invention, instead of performing high-speed calculation by a high-speed computer, a large number of motion conditions or road surface conditions are processed by fuzzy logic. For this reason, it becomes possible to perform the calculation at almost the same speed as the high-speed calculation by the high-speed computer, and it becomes possible to perform the calculation at almost the same accuracy as the calculation by the computer.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall schematic view of a vehicle including a vehicle suspension device according to an embodiment of the present invention. Figure 1
In FIG. 1, only the left side of the vehicle body 1 is shown, but the right side of the vehicle body 1 is similarly configured. In FIG. 1, fluid cylinder devices 3 are provided between the vehicle body 1 and the left front wheel 2FL and between the vehicle body 1 and the left rear wheel 2RL. In each fluid cylinder device 3, a hydraulic chamber 3c is formed by a piston 3b fitted in a cylinder body 3a.
The upper end of the piston rod 3d connected to the piston 3b of each fluid cylinder 3 is connected to the vehicle body 1, and each cylinder body 3a is connected to the left front wheel 2FL or the left rear wheel 2RL.

The hydraulic chamber 3c of each fluid cylinder device 3 is in communication with the gas spring 5 by the communication passage 4, and each gas spring 5 is connected by the diaphragm 5e to the gas chamber 5f and the hydraulic chamber 5.
and the hydraulic chamber 5g is divided into the communication passage 4 and the piston 3.
It communicates with the hydraulic chamber 3c of the fluid cylinder device 3 via b. In the fluid passage 10 connecting the hydraulic pump 8 and each fluid cylinder device 3 so as to be able to supply fluid, the flow rate of the fluid supplied to the fluid cylinder device 3 and the fluid discharged from the fluid cylinder device 3 are A proportional flow rate control valve 9 for controlling the flow rate is provided.

The hydraulic pump 8 is provided with a discharge pressure gauge 12 for detecting the discharge pressure of fluid, and each fluid cylinder device 3 has a hydraulic pressure sensor 1 for detecting the hydraulic pressure in its hydraulic chamber 3c.
3 are provided respectively. Further, by detecting the cylinder stroke amount of each fluid cylinder device 3, each wheel 2FL,
A vertical displacement of the vehicle body with respect to RL, that is, a vehicle height displacement sensor 14 for detecting a vehicle height displacement is provided, and
Vertical acceleration sensors 15a, 15b, 15c for detecting vertical accelerations of the vehicle, that is, vertical accelerations on the springs of the wheels 2FL, 2RL are respectively arranged on the substantially horizontal plane of the vehicle. Left and right front wheels 2FL, 2
Above the FR, on the other hand, vertical acceleration sensors 15c are respectively provided so as to be located at the center portions of the left and right rear wheels in the vehicle width direction, and in the center of gravity of the vehicle body 1 in the vehicle width direction. Lateral acceleration sensor 16 for detecting applied lateral acceleration
Is provided.

In addition to this, the vehicle body 1 has a steering angle sensor 18,
Vehicle speed sensor 19, accelerator opening speed sensor 101, shift change sensor 10 for detecting the presence or absence of a shift change
2. A yaw rate sensor 103, a brake sensor 104 that detects whether the brake is operating, an ABS sensor 105 that detects whether the ABS (anti-brake skid system) is operating, and a TRC that detects whether the TRC (traction control system) is operating. A sensor 106, a wheel phase difference sensor 107 that detects a phase difference between the front wheels 2FL and 2FR and a phase difference between the rear wheels 2RL and 2RR, an engine speed sensor 108, and a system pressure (pressure inside the accumulator 22 described later). System pressure sensor 109 for detecting,
A favorite slide switch mode that detects which mode of the favorite slide switch is selected to change the running characteristics of the vehicle so that either ride comfort or steering stability is emphasized according to the driver's request. Sensor 11
0, a wheel rotation speed sensor 111 and an oil temperature sensor 112 provided on each wheel.

The detection signals from the discharge pressure gauge 12 and each sensor are input to a control unit 17 having a CPU inside, and the control unit 17 is
Based on these detection signals, a calculation is performed according to a predetermined program, the proportional flow rate control valve 9 is controlled, and the suspension characteristics are variably controlled as desired.

FIG. 2 shows that hydraulic fluid is supplied from the hydraulic pump 8 to the fluid cylinder device 3, or the fluid cylinder device 3 is supplied with working fluid.
It is a circuit diagram of a hydraulic circuit that discharges the working fluid from the. Figure 2
In, the hydraulic pump 8 is connected and arranged in parallel with the hydraulic pump 21 for the power steering device driven by the drive source 20, and the accumulator 22 is attached to the discharge pipe 8 a for discharging fluid from the hydraulic pump 21 to the fluid cylinder device 3. The discharge pipe 8a branches into a front wheel side pipe 23F and a rear wheel side pipe 23R on the downstream side of the connection portion of the accumulator 22. Front wheel side piping 23
F is a downstream side of a branch portion with the rear wheel side pipe 23R and branches to a left front wheel side pipe 23FL and a right front wheel side pipe 23FR, and the left front wheel side pipe 23FL and the right front wheel side pipe 23FR are respectively for the left front wheel. Of the fluid cylinder device 3FL and the fluid cylinder device 3FR for the right front wheel.
Similarly, the rear wheel side pipe 23R branches to a left rear wheel side pipe 23RL and a right rear wheel side pipe 23RR on the downstream side of the branching portion, and the left rear wheel side pipe 23RL and the right rear wheel side pipe 23RR respectively. , The left rear wheel fluid cylinder device 3RL and the right rear wheel fluid cylinder device 3RR are in communication with the respective hydraulic chambers 3c.

These fluid cylinder devices 3FL, 3FR, 3
Gas springs 5FL, 5FR, 5RL and 5RR are connected to RL and 3RR, respectively.
RL and 5RR are four gas spring units 5a, 5b,
It is composed of 5c and 5d. These gas spring units 5a, 5b, 5c, 5d are branched into communication passages 4a, 4b, 4 which communicate with the corresponding hydraulic chambers 3c of the fluid cylinder devices 3FL, 3FR, 3RL and 3RR.
It is connected via c and 4d. Also, each gas spring 5
The branch communication passages 4a, 4b, 4c, and 4d of FL, 5FR, 5RL, and 5RR are provided with orifices 25a, 25b, and
25c and 25d are provided, and these orifices 2
Due to the damping action of 5a, 25b, 25c, 25d and the buffering action of the gas enclosed in the gas chamber 5f of the gas springs 5FL, 5FR, 5RL, 5RR, the high frequency vibration applied to the vehicle is reduced.

Of the gas spring units 5a, 5b, 5c and 5d forming the gas springs 5FL, 5FR, 5RL and 5RR, they are located closest to the hydraulic chambers 3c of the fluid cylinder devices 3FL, 3FR, 3RL and 3RR. The first gas spring unit 5a provided and the second gas spring unit 5b adjacent thereto
In the communication passage 4 between and, the passage area of the communication passage 4 is adjusted by taking an open position that opens the communication passage 4 and a closed position that narrows the passage area, and the gas springs 5FL, 5FR, 5RL, 5RR. A switching valve 26 is provided for switching the damping force of 2 in two steps. FIG. 2 shows the switching valve 26 in the open position.

An unload relief valve 28 is connected to the discharge pipe 8a of the hydraulic pump 8 in the vicinity of the upstream side of the connection portion of the accumulator 22. The unload relief valve 28 is connected to the unload relief valve 28.
When the oil discharge pressure measured by the discharge pressure gauge 12 is a predetermined upper limit value, for example, 160 kgf / cm ² or more, it is switched to the open position and the oil discharged from the hydraulic pump 8 is directly returned to the reserve tank 29. On the other hand, when the predetermined lower limit value, for example, 120 kgf / cm ² or less, is switched to the closed position, the oil is supplied to the accumulator 22, and the accumulated pressure value of the hydraulic pressure of the accumulator 22 is controlled to be maintained at the predetermined value. It In this way, each fluid cylinder device 3
The oil is supplied to the accumulator 22 held at a predetermined pressure storage value. FIG. 2 shows the unload relief valve 28 in the closed position.

Since the hydraulic circuits for the left front wheel, the right front wheel, the left rear wheel and the right rear wheel are configured in the same manner, only the hydraulic circuit on the left front wheel side will be described below, and the others will be described below. This is omitted. The proportional flow control valve 9 is a three-way valve, and has a closed position for closing all ports, a supply position for opening the left front wheel side pipe 23FL to the hydraulic pressure supply side, and a left front wheel side pipe 2.
The fluid cylinder device 3 of 3FL can be set at three positions, that is, a discharge position communicating with the return pipe 32. FIG. 2 shows a state in which the proportional flow rate control valve 9 is located at the closed position. Further, the proportional flow rate control valve 9 is provided with a pair of pressure compensating valves 9a. With this pressure compensating valve 9a, when the proportional flow rate control valve 9 is in the supply position or the discharge position, the hydraulic chamber of the fluid cylinder device 3 is The hydraulic pressure in 3c is kept at a predetermined value.

On the fluid cylinder device 3 side of the proportional flow rate control valve 9, there is provided a pilot pressure responsive on-off valve 33 capable of opening and closing the left front wheel side pipe 23FL. This on-off valve 33
Is the hydraulic pressure of the solenoid valve 34 introduced as a pilot pressure when the solenoid valve 34 for guiding the hydraulic pressure of the left front wheel side pipe 23FL of the proportional flow control valve 9 on the hydraulic pump 8 side is opened. When, the on-off valve 33 is the left front wheel side pipe 2
3FL is opened, and the flow rate of the fluid to the fluid cylinder device 3 can be controlled by the proportional flow rate control valve 9.

Further, the hydraulic chamber 3c of the fluid cylinder device 3
When the hydraulic pressure in the inside of the hydraulic chamber abnormally rises, it is opened and connected to the relief valve 35 for returning the fluid in the hydraulic chamber 3c to the return pipe 32, the discharge pipe 8a of the hydraulic pump 8 in the vicinity of the downstream side of the accumulator 22 connection part, Open when the ignition is off,
When the oil stored in the accumulator 22 is returned to the reserve tank 29 and the ignition key interlocking valve 36 for releasing the high pressure state in the accumulator 22 and the oil discharge pressure of the hydraulic pump 8 abnormally rise, A return accumulator 38 that returns oil to the reserve tank 29 and is connected to a hydraulic pump relief valve 37 that lowers the oil discharge pressure of the hydraulic pump 8 and a return pipe 32 and that performs a pressure accumulating action when the fluid is discharged from the fluid cylinder device 3 is provided. Each is provided.

3 to 10 are block diagrams of the fluid control amount calculating device 100 provided in the control unit 17. Fluid control amount calculation device 100
Is a vehicle height displacement signal XFR of the vehicle height displacement sensor 14 of each wheel,
A control system A for controlling the vehicle height to a target vehicle height based on XFL, XRR, XRL, and vehicle height displacement speed signals YFR, YFL, YRR obtained by differentiating the vehicle height displacement signals XFR, XFL, XRR, XRL and A control system B for suppressing the vehicle height displacement speed based on YRL,
A control system C for reducing the vertical vibration of the vehicle based on the vertical acceleration signals GFR, GFL and GR of the three vertical acceleration sensors 15a, 15b and 15c, and the hydraulic pressure sensor 1 for each wheel.
Based on the pressure signals PFR, PFL, PRR, and PRL of the vehicle body 3, the control system D that calculates and suppresses the twist of the vehicle body, and the lateral acceleration detection signal GL from the lateral acceleration sensor 16 detects the lateral direction of the vehicle. It is composed of a control system E for reducing vibration.

The control system A includes a vehicle height displacement sensor 1 for each wheel.
Vehicle height displacement signals XFR, XFL, XRR, X detected by 4
Low-pass filters 40a, 40b, 40c, and 40d that cut high-frequency components are provided to cut RL noise. Further, the control system A outputs the outputs XFR, X from the vehicle height sensors 14 of the left and right front wheels 2FL, 2FR, whose high-frequency components have been cut by the low-pass filters 40a, 40b.
While adding FL, low-pass filters 40c, 40
Left and right rear wheels 2R with high frequency components cut by d
Outputs XRR and XRL from the vehicle height sensors 14 for L and 2RR are added to calculate the bounce component of the vehicle, and the outputs XFR and XFL from the vehicle height sensors 14 for the left and right front wheels 2FL and 2FR. From the added value of, the left and right rear wheels 2RL, 2RR
Pitch component calculator 4 that calculates the pitch component of the vehicle by subtracting the added value of the outputs XRR and XRL from the vehicle height sensor 14 of
2, the left and right front wheels 2FL, 2FR, and the output XFR from the vehicle height sensor 14, XFR-XFL difference XFR-XFL, and the left and right rear wheels 2RL, 2
The difference XRR between the outputs XRR and XRL from the vehicle height sensor 14 of RR-
And a roll component calculation unit 43 that calculates the roll component of the vehicle by adding XRL.

The control system A also includes a bounce component calculator 4
The bounce component of the vehicle and the target average vehicle height TH calculated in 1 are input, and the fluid cylinder device 3 of each wheel in the bounce control is set so that the vehicle height corresponds to the target average vehicle height TH based on the gain KB1. The bounce control unit 44 that calculates the amount of fluid supplied to the vehicle and the pitch component of the vehicle that is calculated by the pitch component calculation unit 42 are input, and based on the gain KP1, the fluid cylinder device 3 of each wheel in the pitch control.
The pitch control section 45 for calculating the amount of fluid supplied to the roller, the roll component calculated by the roll component calculating section 43, and the target roll displacement TR are input, and gain KRF1 and gain KRR are obtained.
Based on 1, the roll control unit 46 calculates the fluid supply amount to the fluid cylinder device 3 of each wheel in roll control so that the vehicle height corresponds to the target roll displacement amount TR.

In this way, the positive and negative signs of the control amounts calculated by the bounce control unit 44, the pitch control unit 45, and the roll control unit 46 are inverted for each wheel, that is, the vehicle height detected by the vehicle height sensor 14. High displacement signal XFR, XFL, XR
R and XRL are inverted so that their positive and negative are opposite,
After that, the respective control amounts of bounce, pitch and roll for each wheel are added, and control flow rate signals QFR1, QFR to the proportional flow rate control valve 9 of each wheel in the control system A are added.
FL1, QRR1 and QRL1 are obtained.

Each low-pass filter 40a, 40b, 40
c, 40d and the bounce calculator 41, the pitch calculator 42, and the roll calculator 43 between the dead band devices 47a, 4b.
7b, 47c, 47d are provided, and the vehicle height sensor 1
4 to low-pass filters 40a, 40b, 40c, 40
Vehicle height displacement signals XFR, XFL, XRR, X input via d
Only when RL exceeds the preset dead zone XH,
These vehicle height displacement signals XFR, XFL, XRR, and XRL are output to the bounce calculator 41, the pitch calculator 42, and the roll calculator 43.

As shown in FIG. 5, the control system B receives input from the vehicle height sensor 14 and receives low-pass filters 40a and 40a.
Differentiator 50a for differentiating the vehicle height displacement signals XFR, XFL, XRR, XRL whose high-frequency components have been cut by b, 40c, 40d and calculating the vehicle height displacement velocity signals YFR, YFL, YRR, YRL according to the following equations. , 50b, 50c, 50d.

Y = (Xn-Xn-1) / T where Xn is the vehicle height displacement at time t, and Xn-1 is the time (t
-1) Vehicle height displacement amount, T is sampling time. Further, the control system B uses the added value of the vehicle height displacement speed signals YFL, YFR on the left and right front wheels 2FL, 2FR to determine the left and right rear wheels 2RL, 2FR.
A pitch component calculator 51 that calculates the pitch component of the vehicle by subtracting the added value of the vehicle height displacement velocity signals YRL and YRR on the RR side.
And the left and right front wheels 2FL, 2FR side vehicle height displacement speed signal YFL,
A roll component calculator 52 that calculates the roll component of the vehicle by adding the difference YFR-YFL of YFR and the difference YRR-YRL of the vehicle height displacement speed signals YRL, YRR on the left and right rear wheels 2RL, 2RR.
It has and.

In this way, the pitch component calculated by the pitch component calculation unit 51 is input to the pitch control unit 53, and the flow control amount to each proportional flow control valve 9 in the pitch control is calculated based on the gain KP2. The roll component calculated by the roll component calculator 52 is input to the roll controller 54, and gain KRF2 and gain KRR2 are input.
Based on the above, the flow rate control amount to each proportional flow rate control valve 9 in the roll control is calculated so that the vehicle height corresponds to the target roll displacement amount TR.

Pitch controller 53 and roll controller 54
The positive and negative signs of the respective control amounts calculated by the above are inverted for each wheel, that is, differentiators 50a, 50b, 50.
c, 50d vehicle height displacement speed signal YFR, Y
FL, YRR, and YRL are inverted so that their positive and negative are opposite, and thereafter, the respective control amounts of pitch and roll for each wheel are added, and the proportional flow control valve 9 of each wheel in control system B is added. Flow rate signals QFR2, QFL2, QRR
2, QRL2 is obtained.

As shown in FIG. 6, the control system C includes vertical acceleration sensors 15a, 15b and 15 whose high-frequency components are cut by the low-pass filters 60a, 60b and 60c.
The vertical acceleration signals GFR, GFL, GR detected by c are added to calculate the bounce component of the vehicle, and the vertical acceleration sensors 15a, 15b mounted above the left and right front wheels 2FR, 2FL. Sum of 1/2 of output (G
FR + GFL) / 2 is subtracted from the output GR of the vertical acceleration sensor 15c provided at the central portion of the left and right rear wheels in the vehicle width direction to calculate the pitch component of the vehicle.
And a roll component calculator 63 that calculates the roll component of the vehicle by subtracting the output GFL of the vertical acceleration sensor 15b on the left front wheel side from the output GFR of the vertical acceleration sensor 15a on the right front wheel side.
It has and.

The control system C receives the bounce control unit 64 to which the calculated value of the bounce component calculated by the bounce component calculation unit 61 is input, and the calculated value of the pitch component calculated by the pitch component calculation unit 62. Pitch controller 65
And a roll control unit 66 to which the calculated value of the roll component calculated by the roll component calculation unit 63 is input. The bounce control unit 64 calculates the control amount of the fluid to each proportional flow rate control valve 9 in the bounce control based on the calculated value of the bounce component and the gain KB3, and the pitch control unit 65 calculates the calculated value of the pitch component and Based on the gain KP3, the control amount of the fluid to the proportional flow rate control valve 9 in the pitch control is calculated, and the roll control unit 66 calculates the proportional flow rate control valve 9 in the roll control based on the calculated value of the roll component and the gains KFR3 and KRR3. And is configured to calculate a controlled amount of fluid to.

The control amount calculated and calculated by the bounce control unit 64, the pitch control unit 65, and the roll control unit 66 in this way is inverted for each wheel, and then the bounce and pitch for each wheel are reversed. And the respective control amounts of the rolls are added, and flow rate signals QFR3, QFL3, QRR3 and QRL to the respective proportional control valves 9 outputted from the control system C are added.
You get 3.

The low-pass filters 60a, 60b and 60c for cutting high frequency components, the bounce component calculator 61, the pitch component calculator 62 and the roll component calculator 63 are provided.
Dead band devices 67a, 67b and 67c are provided between the vertical acceleration sensors 15a, 15b and 15c.
Only when the vertical acceleration signals GFR, GFL, GR input from the low pass filters 60a, 60b, 60c exceed the preset dead zone XG, the vertical acceleration signals GFR, GFL, GR are bounced. The data is output to the calculation unit 61, the pitch component calculation unit 62, and the roll component calculation unit 63.

As shown in FIG. 6, the control system D receives the hydraulic pressure detection signals PFL and PFR detected by the hydraulic pressure sensor 13 of the fluid cylinder device 3 of the left and right front wheels 2FL and 2FR, and the high frequency components thereof are input. After being cut by the low-pass filters 70a and 70b, a difference (PFR-PFL) between the hydraulic pressures of the hydraulic chambers 3c of the left and right front wheels 2FR and 2FL of the fluid cylinder device 3,
A ratio Pf = (PFR−PFL) / (PFR + PFL) with the added value (PFR + PFL) is calculated, and the calculated hydraulic pressure ratio Pf is the threshold hydraulic pressure ratio ωL.
On the other hand, when -ωL <Pf <ωL, the calculated hydraulic pressure ratio Pf is output as it is, while Pf <-ωL
Alternatively, when Pf> ωL, the threshold fluid pressure ratio −ω
The hydraulic pressure detection signal P detected by the front wheel side hydraulic pressure ratio calculation unit 71a that outputs L or ωL, and similarly, by the hydraulic pressure sensors 13 of the fluid cylinder devices 3 of the left and right rear wheels 2RL, 2RR.
RL and PRR are input, and the high frequency components thereof are cut by the low-pass filters 70c and 70d, and then the difference (PRR-) between the hydraulic pressures of the hydraulic chambers 3c of the left and right rear wheels 2RR and 2RL. PRL) and their added value (PRR + P
RL) ratio Pr = (PRR-PRL) / (PRR + PRL) for calculating the rear wheel hydraulic pressure ratio calculation unit 71b, and multiplying the rear wheel hydraulic pressure ratio Pr by a predetermined value based on the gain ωF. After that, a warp control unit 71 that subtracts this from the hydraulic pressure ratio Pf on the front wheel side is provided, and the output of the warp control unit 71 is multiplied by a predetermined value using a gain ωA, and thereafter, a gain ωc is used on the front wheel side. Then, the flow rate signal QFR4 to each proportional flow rate control valve 9 in the control system D is inverted by multiplying by a predetermined value, and further inverting one of the wheels so that the fluid supply control amount for each wheel is opposite in polarity between the left and right wheels. , QFL4, QRR4, QRL4 are obtained.

As shown in FIG. 10, the control system E receives the lateral acceleration detection signal applied to the width direction of the vehicle detected by the lateral acceleration sensor 16 and, after the high frequency component is cut by the low pass filter 80. , Gain Kg
The control amount is calculated based on the above, and the left and right front wheels 2FL and 2FR are further multiplied by a predetermined amount based on the gain AGF, and thereafter, the positive and negative fluid supply control amounts for the left and right wheels are reversed. , The fluid supply control amount for the left front wheel 2FL is reversed, while for the left and right rear wheels 2RL, 2RR, the fluid supply control amounts for the left and right wheels are reversed so that the positive and negative signs are opposite. By reversing the fluid supply control amount, flow rate signals QFR5, QFL5, QRR5, QRL5 to each proportional flow rate control valve 9 in the control system E are obtained.

Each control system A obtained as described above,
The flow rate signals to the proportional flow rate control valves 9 in B, C, D and E are added for each wheel, and further the left and right front wheels 2 are added.
FL, 2FR are multiplied by the gain AF, and the total flow rate signals QFR, QFL, QRR, Q to each proportional flow rate control valve 9 are multiplied.
RL is obtained. Tables 1 and 2 shown in FIGS. 11 and 12 respectively show examples of reference maps of control gains used in the control systems A, B, C, D and E stored in the control unit 17. , 7 modes are set according to the driving state.

In Table 1 and Table 2, mode 1 is the value of each control gain for 60 seconds after the engine is stopped,
In mode 2, the ignition switch is turned on, but the vehicle is stopped, and the control gain values are in the state where the vehicle speed is zero. In mode 3, the lateral acceleration GL of the vehicle is 0.1 or less in the straight running state. The value of each control gain is shown. When the reverse roll mode is selected by the roll mode selection switch (not shown), the mode 4 is set to the mode 5 when the lateral acceleration GL of the vehicle exceeds 0.1 and the vehicle is slowly turning below 0.1. Instead, it shows the value of the selected control gain, and when the vehicle speed becomes 120 km / h or more, the mode is automatically switched to the mode 5 even if the reverse roll mode is selected. In mode 5, the lateral acceleration GL of the vehicle exceeds 0.1 and 0.3
In Mode 6, the lateral acceleration GL of the vehicle exceeds 0.3 and 0.5
The values of the respective control gains in the following middle turning state and the values of the respective control gains in the steep turning state in which the lateral acceleration GL of the vehicle exceeds 0.5 are shown in mode 7.

In Tables 1 and 2, QMAX indicates the maximum flow control amount supplied to the proportional flow control valve 9 of each wheel, and PMAX indicates the hydraulic chamber 3c of the fluid cylinder device 3.
The maximum pressure in the fluid cylinder device 3 is set so that the fluid does not flow backward from the fluid pressure chamber 3c of the fluid cylinder device 3 to the accumulator 22, and PMIN is the fluid pressure chamber 3c of the fluid cylinder device 3. Is set so that the pressure in the hydraulic chamber 3c of the fluid cylinder device 3 is excessively decreased and the gas spring 5 is not fully extended and damaged.

In Tables 1 and 2, each control gain is set so that the suspension control with emphasis on traveling stability is performed as the mode number increases, except for mode 4. As described above, the bounce control gain KB1, pitch control gain KP1, roll control gain KRF1, KRR1 in vehicle height control, pitch control gain KP2, roll control gain KRF2, KRR in vehicle height displacement speed control
2, bounce control gain KB3, pitch control gain KP3, roll control gain KRF3, KRR3 in vertical vibration control,
Based on the warp control gain ωA in the warp control and the gain Kg in the lateral vibration control, each wheel 2FR, 2
The flow rate of the working fluid sent to FL, 2RR, 2RL is determined.

However, in order to achieve a high level of both steering stability and riding comfort, these gains are used for operating conditions such as vehicle speed, vertical acceleration, yaw rate, and road surface roughness such as road surface roughness and road surface friction coefficient. It is preferable to change it according to the motion state of the vehicle such as the state. Therefore, in this embodiment, depending on the motion state and the road surface state of the vehicle,
Gain control means 200 for changing each of the above-mentioned gains by using fuzzy logic is incorporated in the control unit 17.

FIG. 13 is a flow chart showing the operation of the gain control means 200. First, the gain control means 200
Is (A) road surface roughness, (B) road surface waviness as a road surface condition, (C) vehicle speed, (D) lateral acceleration, (E) accelerator opening speed, (F) longitudinal acceleration, as a driving condition, (G) Presence or absence of shift change, (H) Steering angular velocity,
(I) yaw rate, (J) braking device (brake) operation, (K) ABS operation, (L) TRC operation, (M) 4WS operation,
To the extent that it is in the in-phase state, as an external state (N)
Engine speed, (O) system pressure, (P) favorite slide switch mode, (Q) road friction coefficient, (R)
Each amount of oil temperature is measured by the above-mentioned sensors 14, 15a, 15b, 1
5c, 16, 18, 19, 101, 102, 103, 1
04, 105, 106, 107, 108, 109, 11
It detects based on the detection signal from 0,111,112.

Next, the gain control means 200, based on these factors, bounce control gain KB1, pitch control gain KP1, roll control gains KRF1, KRR1 in vehicle height control, pitch control gain KP2, roll in vehicle height displacement speed control. Control gains KRF2, KRR2, bounce control gain KB3 in vertical vibration control, pitch control gain KP3, roll control gains KRF3, KRR3, warp control gain ωA in warp control, and gain Kg in lateral vibration control are made larger than standard value 1. Or to reduce it or leave it at the standard value of 1. Further, when increasing or decreasing each gain, how much to increase or decrease is determined.

The control unit 17 has the above-mentioned (A)
For each of the factors (R) to (R), membership functions corresponding to the case where the gain of the factor is increased and the case where the gain of the factor is decreased are stored in advance, and after the magnitude of each gain is set as described above, The gain control means 200 reads the membership function corresponding to the setting of the magnitude of each gain from the control unit 17.

Then, the gain control means 200 calculates the value of each gain based on each membership function using fuzzy logic to obtain the gain correction coefficient α. The calculation by this fuzzy logic will be described later. The gain control means 200 calculates the correction gain by multiplying the above-mentioned gains by the gain correction coefficient α.

After that, the gain control means 200 calculates the flow rate of the working fluid to be supplied to each wheel by using this correction gain in place of each of the above-mentioned gains, and the control unit 17 sends a signal representing the value to the pump 8. Drive source 2 for driving
Send to 0. An example of calculation of the correction gain by the gain control means 200 will be described below with reference to FIGS. 14 to 39.

The control unit 17 controls the vertical acceleration G from the vertical acceleration sensors 15a, 15b, 15c.
When the signals representing FR, GFL and GR are received, they are passed through a high pass filter to cut low frequency components. Next, the number of times that the values of the vertical accelerations GFR, GFL, GR become equal to or greater than a predetermined acceleration value (eg, 1 G) within a fixed time (eg, 3 seconds) is measured. After obtaining the number of times for each of the three vertical accelerations GFR, GFL, GR, three vertical acceleration sensors 15a, 1
In order to eliminate the variations in the detected values of 5b and 15c, the average value of the values of three times is calculated and used as the index value indicating the roughness of the road surface.

When the index value indicating the roughness of the road surface is equal to or greater than a predetermined value, the gain control means 200 determines that the road surface is rough, and the rough surface reduces the riding comfort. The target gain is set so that the required gain is increased or decreased so that the stability does not decrease. That is, as shown in FIGS. 32 and 33, when the degree of road surface roughness is large, the pitch control gain KP2, the roll control gains KRF2, KRR2 in the vehicle height displacement speed control, the bounce control gain KB3 in the vertical vibration control, and the pitch control are obtained. Gain KP3, roll control gain KRF
3, KRR3, warp control gain ω in warp control
The target gain for reducing the reference vehicle height TH is set while the gain Kg in A and the lateral vibration control is reduced.

That is, when the road surface is rough,
In order to prevent the deterioration of the riding comfort caused by the vibration of the vehicle being transmitted to the passenger compartment, all gains related to the vertical acceleration are reduced. The bounce control gain KB1, the pitch control gain KP1, the roll control gains KRF1, KRR1 in the vehicle height control, the roll amount and the pitch amount gain for the target vehicle height control, and the gain for the maximum discharge amount of the pump 8 are not changed. That is, the standard value 1 is left unchanged.

Here, when the gain is decreased or increased, the gain control means 200 also determines the variation range of the gain in consideration of the magnitude of the influence of the road surface roughness. That is, the pitch control gain KP2 and the roll control gains KRF2 and KRR2 in the vehicle high displacement speed control are set to target gains with a relatively large gain reduction range. Similarly, the warp control gain ωA and the lateral vibration in the warp control are set. The control gain Kg is also set to a target gain with a relatively large reduction range. On the other hand, the bounce control gain KB3, the pitch control gain KP3, the roll control gains KRF3, KRR3 in the vertical vibration control, and the gain for the reference vehicle height TH in the target vehicle height control are set to target gains with a relatively small reduction range. .

In FIGS. 32 and 33, the target gain set so that the gain increase width is relatively small with respect to the standard gain value of 1 is "PM", and the gain increase width is relatively large. Set the target gain to "P
B ". On the other hand, the target gain set so that the gain reduction range is relatively small with respect to the standard gain value of 1 is “NM”, and the target gain set so that the gain reduction range is relatively large is “NB”. ".

The degree of increase or decrease indicated by these PM, PB, NM, and NB does not have to be the same for each of the factors (1) to (13) described above, but varies for each factor. It is possible. Needless to say, the same factor represents the same degree of variation. “ST” represents a state in which the target gain is not set and the standard value 1 is left as it is.

When the index value indicating the roughness of the road surface is less than the predetermined value, the target gain is not set. That is, each gain remains the standard value 1. Further, the control unit 17 includes a vertical acceleration sensor 15a,
Vertical acceleration GF transmitted from 15b and 15c
The signals representing R, GFL and GR are passed through a low pass filter to cut high frequency components. Then, the vertical accelerations GFR, GFL,
The number of times the values of the GR bounce component and the pitch component become equal to or less than a predetermined acceleration value (for example, 0.4 G) is measured. After the number of times is calculated for each of the bounce component and the pitch component, an average value of the values of these two times is calculated and used as an index value representing the undulation of the road surface.

When the index value indicating the undulation of the road surface is less than a predetermined value, the gain control means 200 determines that the small undulation is small and therefore the undulation of the road surface is large, and when the roughness of the road surface is large. Similarly, the target gain is set by increasing or decreasing the required gain. Specifically, as shown in FIGS. 32 and 33, when the swell of the road surface is large, the pitch control gain KP1 in the vehicle height displacement control is set to NM, and the pitch control gain KP2 in the vehicle height displacement speed control is set to NB. Pitch control gain KP3 in vertical vibration control is set to PM, and roll control gains KRF3 and KRR in vertical vibration control are also set.
Set 3 to NM.

That is, since the swell of the road surface most affects the pitch component of the vibration of the vehicle, the pitch control gain KP3 in the vertical vibration control is increased, while the pitch control gain KP1 in the vehicle height displacement control is prevented in order to prevent the ride comfort from decreasing. And the pitch control gain KP2 in the vehicle height displacement speed control is lowered. Target gains for gains other than these are not set and are left at the standard value 1.

When the index value of the swell of the road surface is equal to or larger than the predetermined value, the target gain is not set. That is, each gain remains the standard value 1. Further, the control unit 17 receives the vehicle speed signal from the vehicle speed sensor 19, and the gain control means 200, based on this signal,
It is determined whether the vehicle speed V is a predetermined value (for example, 75 km / h) or more. When the vehicle speed V is equal to or higher than a predetermined value,
Assuming that the vehicle speed is high, the target gain is set so that the required gain is high or low. That is, when the vehicle speed V is high, roll control gains KRF1, KRR1 in vehicle height displacement control, pitch control gain KP2, roll control gains KRF2, KRR in vehicle height displacement speed control.
2, pitch control gain KP3, roll control gains KRF3, KRR3 in vertical vibration control, warp control gain ωA in warp control, gain K in lateral vibration control
g and the target gain for the reference vehicle height TH in the target vehicle height control are set to PM.

That is, when the vehicle speed is high, the target gain is set from the viewpoint that the driving stability is more important than the riding comfort. Target gains are not set for other gains. That is, the standard gain 1 is left unchanged. If the vehicle speed V is less than the predetermined value, the target gain is not set. That is, each gain remains the standard value 1.

Next, the control unit 17 receives the signal from the lateral acceleration sensor 16, and the gain control means 200 determines whether the lateral acceleration GL is a predetermined value (for example, 0.2 G) or more based on this signal. Determine whether or not. When the lateral acceleration GL is equal to or greater than the predetermined value, the target gains for the roll control gains KRF3 and KRR3 in the vertical vibration control and the warp control gain ωA in the warp control are set to PM.

That is, the fact that the lateral acceleration is large indicates that the vehicle is in a sharp turning state, and therefore the target gain is set from the viewpoint of maintaining the proper posture of the vehicle. The gains other than these are left at the standard value 1.
If the lateral acceleration GL is less than the predetermined value, the target gain is not set and all the gains are left at the standard value 1.

Next, the control unit 17 receives a signal from the accelerator opening speed sensor 101, and the gain control means 200 determines whether or not the accelerator opening speed is a predetermined value (for example, 10 m / sec) or more based on this signal. To determine. If it is equal to or more than the predetermined value, the target gain for the pitch control gain KP1 in the vehicle height displacement control, the pitch control gain KP2 in the vehicle height displacement speed control, and the pitch control gain KP3 in the vertical vibration control is set to PB.

For the gains other than these, the standard value 1 is left unchanged. When the accelerator opening speed is less than the predetermined value, the target gain for each gain is not set and the standard value 1 is left unchanged. Next, the control unit 17 differentiates the signal value from the vehicle speed sensor 19 to calculate the longitudinal acceleration of the vehicle, and the gain control means 200.
This longitudinal acceleration value is a predetermined value (for example, 0.2G)
It is determined whether or not the above. When it is equal to or more than the predetermined value, the pitch control gain KP2 in the vehicle height displacement speed control,
The target gain for the pitch control gain KP3 in the vertical vibration control is set to PB.

The fact that the longitudinal acceleration is large means that the vehicle is in a sudden start or in a sudden braking state. Therefore, the target gain is set particularly from the viewpoint of reducing the pitch component of vibration. For gains other than these, the standard value 1 is left unchanged. When the longitudinal acceleration is less than the predetermined value, the target gain for each gain is not set and the standard value 1 is left unchanged.

Next, the control unit 17 receives the signal from the shift change sensor 102, and the gain control means 200 determines whether or not a shift change has been performed. When a shift change is performed, the target gain for the pitch control gain KP1 in vehicle height displacement control, the pitch control gain KP2 in vehicle height displacement speed control, and the pitch control gain KP3 in vertical vibration control is set to PM.

That is, when a shift change is made,
Pitch vibration occurs due to a shock at the time of shift change, and thus a target gain for suppressing pitch vibration is set. Standard value 1 for gains other than these
Leave it as it is. If no shift change is performed, the target gain for each gain is not set and the standard value 1 is left unchanged.

Next, the control unit 17 differentiates the signal value from the steering angle sensor 18 to calculate the steering angular velocity,
The gain control means 200 determines whether or not the steering angular velocity is a predetermined value (for example, 3 m / sec) or more. When it is equal to or more than the predetermined value, the target gains for the roll control gains KRF2, KRR2 in the vehicle high displacement speed control, the roll control gains KRF3, KRR3 in the vertical vibration control, and the warp control gain ωA in the warp control are set to PM.

That is, the fact that the steering angular velocity is high indicates that the vehicle is in a steep steering state.
In particular, in order to prevent the roll, the target gain is set so as to increase the control gain for the roll component. The gains other than these are left at the standard value 1. When the steering angular velocity is less than the predetermined value, the target gain for each gain is not set and the standard value 1 is left unchanged.

Next, the control unit 17 receives the signal from the yaw rate sensor 103, and the gain control means 200 determines whether or not the yaw rate is equal to or higher than a predetermined value. If it is equal to or more than the predetermined value, the target gain for the roll control gains KRF3, KRR3 in the vertical vibration control and the gain Kg in the lateral vibration control is set to PM, and the target gain for the warp control gain ωA in the warp control is set to PB. To do.

The gains other than these are left at the standard value 1. If the yaw rate is less than the predetermined value, the target gain for each gain is not set and the standard value 1 is left unchanged. Next, the control unit 17 receives a signal indicating whether or not the brake is operated from the brake sensor 104, and the gain control means 200 determines whether or not the brake is operated based on this signal. If the brake is operating and the vehicle speed is equal to or higher than the specified value,
The target gain for the pitch control gain KP1 in the vehicle height displacement control, the pitch control gain KP2 in the vehicle height displacement speed control, and the pitch control gain KP3 in the vertical vibration control is P.
Set to B. Standard value 1 for gains other than these
Leave it as it is. When the brake is operating and the vehicle speed is less than the predetermined value, the target gain for the pitch control gain KP2 in the vehicle height displacement speed control is set to PM.

For the gains other than this gain, the standard value 1 is left unchanged. When the brake is not operating, the target gain for each gain is not set and the standard value 1
Leave it as it is. Next, the control unit 17
Receives a signal indicating whether or not the ABS is operating from the ABS sensor 105, and the gain control means 200 determines whether or not the ABS is operating based on this signal. When the ABS is operating, the target gain for the warp control gain ω A in the warp control and the gain Kg in the lateral vibration control is set to PM, and the target gain is not set for the gains other than these, and the standard gain is set. Leave the value as 1.

When the ABS is not operating, the target gain for each gain is not set and the standard value 1 is left unchanged. Next, the control unit 17 receives a signal indicating whether or not the TRC is activated from the TRC sensor 106, and the gain control means 200 is based on this signal.
Determine whether or not is operating. When TRC is operating, pitch control gain K in vertical vibration control
P3, the target gain for the warp control gain ωA in warp control is set to PB.

Target gains are not set for gains other than these, and the standard value 1 is left unchanged. When the TRC is not operating, the target gain for each gain is not set and the standard value 1 is left unchanged. Next, the control unit 17 receives a signal indicating the phase difference between the wheels from the wheel phase difference sensor 107, and the gain control means 200 determines that the four wheels are in phase with each other and the rear wheels are steered based on this signal. It is determined whether the angle is equal to or larger than a certain value.
If the determination result is YES, the target gain for the warp control gain ωA in the warp control is set to P
Set to B.

The gains other than these are left at the standard value 1. If the determination result is NO, the target gain for each gain is not set and the standard value 1 is left unchanged. Next, the control unit 17 receives the signal from the engine speed sensor 108, and the gain control means 2
00 determines whether or not the engine speed is equal to or higher than a predetermined value (for example, 3000 RPM) based on this signal. When the engine speed is equal to or higher than this predetermined value, the target gain for the maximum flow rate of the pump 8 is set to PM.

This is because the required maximum flow rate of the pump changes according to the engine speed, so that when the engine speed is high, the control gain for the maximum flow rate of the pump is increased to increase the maximum flow rate of the pump. Is. The other gains are left at the standard value 1. When the engine speed is less than the predetermined value, the target gain for the maximum flow rate of the pump 8 is not set and the standard value 1 is left unchanged.

Next, the control unit 17 receives the signal from the system pressure sensor 109, and the gain control means 200 uses this signal to set the system pressure (accumulated value in the accumulator 22) to a predetermined value (for example, 5 kg).
/ Cm ² ) or less. When the system pressure is equal to or lower than a predetermined value, the pitch control gain KP2 in the vehicle height displacement speed control, the bounce control gain KB3, the pitch control gain KP3 in the vertical vibration control, and the target gain for the maximum discharge amount of the pump in the target vehicle height control. Is set to NB, roll control gain KRF2,
KRR2, roll control gain KRF3 in vertical vibration control,
The target gain for the warp control gain ω A in KRR3 and warp control is set to NM.

The small system pressure means that the amount of oil stored in the accumulator 22 is small and the necessary control cannot be performed sufficiently. Therefore, the control gain is lowered and the target gain is set so as to wait for the recovery of the accumulated pressure amount of the accumulator. However, in consideration of steering stability, only the roll amount gain in the target vehicle height control is increased.

The gains other than these are left at the standard value 1. When the system pressure exceeds a predetermined value, the target gain for each of the above gains is not set and the standard value 1 is left unchanged. Next, the control unit 17 receives the signal from the favorite slide switch mode sensor 110, and the gain control means 200 determines whether the ride comfort mode or the steering stability mode is selected based on this signal. When the ride comfort mode is selected, the pitch control gain KP in vehicle height displacement speed control
2, Set the target gain for the roll control gains KRF2 and KRR2 to NB. The gains other than these are left at the standard value 1. On the other hand, when the steering stability mode is selected, the pitch control gain KP2, the roll control gains KRF2, KRR2 in the vehicle height displacement speed control, the warp control gain ωA in the warp control, and the reference vehicle height in the target vehicle height control are compared. Set the target gain to PB.

That is, when the driver wants to emphasize the riding comfort, the gain relating to the vehicle height displacement speed control which most affects the riding comfort is lowered, and when the driver wants to emphasize the steering stability, those gains are increased. By doing so, the driver's request is met. The gains other than these are left at the standard value 1.

Next, the control unit 17 receives a signal representing the rotation speed of each wheel from the wheel rotation speed sensor 111, and the gain control means 200, based on this signal value,
The estimated value of the friction coefficient μ of the road surface is obtained from the difference in the rotational speed of each wheel. Further, the gain control means 200 determines that the friction coefficient μ
Is below a predetermined value (for example, 0.3). When the coefficient of friction is less than a predetermined value, pitch control gain KP2 and roll control gain KRF in vehicle height displacement speed control
The target gain for the roll control gains KRF3 and KRR3 in 2, KRR2 and vertical vibration control is set to NB.

When the friction coefficient μ of the road surface is small, the vehicle is likely to slip. Slip is mainly caused by a large load movement in the vehicle. Therefore, if the vehicle is made to roll easily, the degree of load movement caused by the roll is reduced and the slip is less likely to occur. Therefore, when the friction coefficient μ of the road surface is small, the target gain is set so that the control gain relating to the roll control is reduced.

The gains other than these are left at the standard value 1. If the friction coefficient μ of the road surface exceeds the specified value,
The target gain for each gain is not set and is left at the standard value 1. Next, the control unit 17 receives a signal indicating the oil temperature from the oil temperature sensor 112, and the gain control means 200 determines whether the oil temperature is equal to or higher than a predetermined temperature.
When the temperature is higher than a predetermined temperature, pitch control gain KP2, roll control gain KRF2, KRR in vehicle high displacement speed control
Set the target gain for 2 to PB. The gains other than these are left at the standard value 1. When the oil temperature is lower than the predetermined temperature, the target gain for the pitch control gain KP2 and the roll control gains KRF2, KRR2 in the vehicle height displacement speed control is set to NB.

The gains other than these are left at the standard value 1. As described above, the target gain for each gain is set for each amount of the motion state of the vehicle (road surface state, driving state and external state shown in FIGS. 32 and 33). Next, the gain control means 200 reads from the control unit 17 a membership function (shown in FIGS. 14 to 31) that is predetermined corresponding to each of the factors (A) to (R) described above. The horizontal axis of the membership function represents the quantity of each factor, and the vertical axis represents the number (0 or more and 1 or less) indicating the level of gain according to the quantity of each factor.

For example, as shown in FIG. 32, all the target gains for the bounce control gain KB1 in the vehicle height displacement control are ST, so the bounce control gain KB1 is not changed. As described above, for example, the pitch control gain KP1 in the vehicle height displacement control is NM for road swells, PB for accelerator opening speed, PM for shift changes, and brake operation (high vehicle speed). ), The target gain of PB is set, but the pitch control gain KP1 in this vehicle height displacement control is changed as follows.

First, of the membership function shown in FIG.
Index value that indicates the swell of the road surface from the area that represents "NM"
Value Y on the vertical axis₁(0 ≦ Y₁Find ≦ 1). example
For example, if the index value showing the swell of the road surface is 0.6
Is the corresponding Y value on the vertical axis. ₁= 0.5 is read.
Similarly, from the membership function shown in FIG.
Value Y on the vertical axis corresponding to the opening speed₂(0 ≦ Y₂≦ 1)
It For example, the accelerator opening speed is 0.25a (a is when fully opened)
Speed), and the corresponding value on the vertical axis
Y₂= 0.25 is read.

Next, the membership function shown in FIG.
From t seconds after the shift change (0 ≦ t ≦
Value Y on the vertical axis corresponding to 1)₃(0 ≦ Y₃≦ 1)
It For example, if t = 0.5, the corresponding vertical axis
As the value of Y₃= 0.5 is read. Finally, the brake
During operation, and the vehicle speed V is a predetermined value (for example, V =
75 km / h) or higher, the members shown in FIG.
From the PB area of the barship function, the vertical corresponding to the vehicle speed V
Axis Y_Four(0 ≦ Y_FourFind ≦ 1). For example, the brake
If the vehicle speed V during operation is V = 80, it corresponds
Y as the vertical axis value _FourRead = 0.6.

In this way, after reading the four Y values corresponding to the target gain from the membership function for each factor, the gain correction coefficient for the gain to be changed from the gain correction coefficient α reading map shown in FIG. Read α. For example, as described above, the four Y values for each factor in the pitch control gain KP1 in the vehicle height displacement control were read as follows. (1) For road swell Y ₁ = 0.5 (NM) (2) For accelerator opening speed Y ₂ = 0.25 (PB) (3) For shift change Y ₃ = 0.5 (PM) (4) For brake operation (high vehicle speed) Y ₄ = 0.6 (PB) FIG. 34 is a graph showing the relationship between each of NB, NM, PM, PB and the gain correction coefficient α. . NB, NM, PM,
PBs are weighted respectively, and NB, NM, P
The range of the gain correction coefficient α corresponding to M and PB is large.

After reading the four Y values, the gain correction coefficient α corresponding to those Y values is obtained as follows. First, the value of Y ₁ = 0.5 for the swell of the road surface is used. As shown in FIG. 35 (A), 0.
A horizontal line is drawn from the point indicating 5 and intersects the triangle represented by the gain variation width NM with respect to the swell of the road surface. After this,
The control unit 17 calculates the area A ₁ of the trapezoidal area S ₁ surrounded by the horizontal line, the abscissa axis (the axis representing the gain correction coefficient α) and the triangle NM, and further, the abscissa axis of the center of gravity G ₁ of the area S _1. The value R _{1 at} is calculated.

Thereafter, similarly, Y ₂ = 0.25 for the accelerator opening speed and Y ₃ = 0. For the shift change.
5. Using each value of Y ₄ = 0.6 for brake operation (high vehicle speed), as shown in FIGS. 35 (B), (C), and (D), corresponding PB, PM, PB Area A ₂ , A ₃ , A of the trapezoidal regions S ₂ , S ₃ , S _4
4 and then the values R ₂ , R ₃ , R on the abscissa axis of the centers of gravity G ₂ , G ₃ , G ₄ of the regions S ₂ , S ₃ , S ₄
Ask for ₄ .

In this way, the four regions S ₁ , S ₂ ,
S _3, the area A ₁ of _{S 4, A 2, A 3} , A 4 and the center of gravity G
_After obtaining ₁ , G ₂ , G ₃ , and G ₄ , these four regions S ₁ , S ₂ , S ₃ , and S ₄ are combined as shown in FIG. Next, the value R on the abscissa axis of the center of gravity G of this combined area is obtained according to the following equation. R = (A ₁ · R ₁ + A ₂ · R ₂ + A ₃ · R ₃ + A ₄ · R
₄ ) / (A ₁ + A ₂ + A ₃ + A ₄ ) The value R thus obtained corresponds to the gain correction coefficient α of the pitch control gain KP1 in the vehicle height displacement control, and this gain correction coefficient α is the undulation of the road surface or the like. In addition to considering all the gain fluctuations due to each factor, the values are weighted according to the magnitude of the gain fluctuations due to each factor.

The gain control means 200 calculates the correction gain for the pitch control gain KP1 in the vehicle height displacement control using the gain correction coefficient α thus obtained by the following equation. Correction gain = (gain KP1) × (gain correction coefficient α) Hereinafter, the roll control gains KRF1, KRR1 in the vehicle height displacement control are obtained in the same manner as the gain correction coefficient α for the pitch control gain KP1 in the vehicle height displacement control is obtained. Pitch control gain KP2, roll control gains KRF2, KRR2 in vehicle high displacement speed control, bounce control gain KB3, pitch control gain KP3, roll control gains KRF3, KRR3 in vertical vibration control, warp control gain ωA in lateral control, lateral vibration A gain correction coefficient for each of the gains Kg in control is obtained.

In the reference vehicle height control and the roll amount control in the target vehicle height control, unlike the above case, the control amounts are directly obtained as follows. As shown in FIG. 33, with respect to the reference vehicle height control, (1) the gain variation due to the roughness of the road surface is NM, (2) the gain variation due to the vehicle speed is PM, and (3) the gain variation due to the favorite slide switch mode is PB. It is supposed to be performed in each range.

First, in the membership function for road surface roughness shown in FIG. 14, the value Y ₁ (0 ≦ Y ₁ ≦ 1) on the vertical axis from the region representing NM to the index value representing the road surface roughness
Ask for. For example, when the index value indicating the roughness of the road surface is 0.6, the corresponding value on the vertical axis Y ₁ = 0.45
To read. Similarly, the value Y ₂ (0 ≦ Y ₂ ≦ 1) on the vertical axis corresponding to the vehicle speed is obtained from the region representing PM in the membership function for the vehicle speed shown in FIG. For example, when the vehicle speed is 70 km / h, Y ₂ = 0.5 is read as the value of the vertical axis corresponding to it.

Next, of the membership functions for the favorite slide switch shown in FIG. 29, the value Y _{3 on the} vertical axis corresponding to the index value represented by the favorite slide switch from the PB region corresponding to the steering stability mode. (0 ≦ Y ₃
Find ≦ 1). For example, if the index value represented by the favorite slide switch is 4, Y ₃ = 0.65 is read as the value on the vertical axis corresponding thereto.

After reading the three Y values in this manner, these three Y values are applied to the membership function for the reference vehicle height shown in FIG. 37 (A). First, as shown in FIG. 38, a horizontal line is drawn from the 0.45 point on the vertical axis to intersect the triangular region NM. Thereafter, the control unit 17 calculates the area A ₁ of the trapezoidal area S ₁ surrounded by this horizontal line and the horizontal axis and the triangle NM, further obtains the value R ₁ in the abscissa of the center of gravity G ₁ region S ₁ .

Similarly, Y ₂ =
As shown in FIGS. 38 (B) and 38 (C), using the values of 0.5 and Y ₃ = 0.65 for the steering stability mode selected by the favorite slide switch, the corresponding FIG.
A trapezoidal area S is formed by using 7 (A) PM and PB triangles.
The areas A ₂ and A ₃ of ₂ and S ₃ are calculated, and then the values R ₂ and R ₃ on the abscissa axis of the centers of gravity G ₂ and G ₃ of the regions S ₂ and S ₃ are obtained.

In this way, the three regions S ₁ , S ₂ ,
Areas A ₁ , A ₂ , A _{3 of} S ₃ and centers of gravity G ₁ , G ₂ , G
_{After 3} is obtained, these three regions S ₁ , S ₂ , and S ₃ are combined as shown in FIG. Next, the value R on the abscissa axis of the center of gravity G of this combined area is obtained according to the following equation. R = (A ₁ · R ₁ + A ₂ · R ₂ + A ₃ · R ₃ ) / (A ₁
+ A ₂ + A ₃ ) The value [mm] on the abscissa axis corresponding to this value R becomes the reference vehicle height in the target vehicle height control. As shown in FIG. 39, the value of R is negative. This is because the gain required by the roughness of the road surface is low, the gain required by the vehicle speed is high, and the gain required by the favorite slide switch is higher than the gain at the vehicle speed.
By summing up the individual required gain values, it means that the reference vehicle height is set low as a result.

FIG. 37 also shows the maximum discharge amount control in the roll amount control at the target vehicle height and the maximum flow rate control of the pump.
It is similarly performed using the membership functions shown in (B) and (C). Although the above-described factors (A) to (R) are used as the driving state of the vehicle in the embodiments described above, it is possible to further use other factors. Alternatively, each of the factors (A) to (R) described above can be further subdivided into cases according to, for example, vehicle speed and acceleration.

[0099]

As described above, according to the present invention, a large number of vehicle motion states or road surface state quantities are arithmetically processed by fuzzy logic. By using the fuzzy logic, a large number of control gain setting changes can be calculated in a short time without using a high-speed calculation means such as a computer.

Further, by using the fuzzy logic, the calculation can be performed with almost the same accuracy as the calculation by the computer, and the vehicle can be controlled according to the driver's feeling.

[Brief description of drawings]

FIG. 1 is an overall schematic view of a vehicle including a vehicle suspension device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a hydraulic circuit that connects between a hydraulic pump and a fluid cylinder device.

FIG. 3 is a drawing showing a part of a block diagram of a fluid supply amount calculation device provided in a control unit.

FIG. 4 is a drawing showing a part of a block diagram of a fluid supply amount calculation device provided in a control unit.

FIG. 5 is a diagram showing a part of a block diagram of a fluid supply amount calculation device provided in a control unit.

FIG. 6 is a diagram showing a part of a block diagram of a fluid supply amount calculating device provided in a control unit.

FIG. 7 is a drawing showing a part of a block diagram of a fluid supply amount calculation device provided in a control unit.

FIG. 8 is a diagram showing a part of a block diagram of a fluid supply amount calculation device provided in a control unit.

FIG. 9 is a drawing showing a part of a block diagram of a fluid supply amount calculation device provided in a control unit.

FIG. 10 is a diagram showing a part of a block diagram of a fluid supply amount calculating device provided in a control unit.

FIG. 11 is a table showing an example of a reference map of control gains used in each control system stored in the control unit.

12 is a continuation of the table shown in FIG.

FIG. 13 is a flowchart of an operation of the vehicle suspension device according to the present invention.

FIG. 14 is a diagram showing a membership function with respect to road surface roughness.

FIG. 15 is a diagram showing a membership function for road swell.

FIG. 16 is a diagram showing a membership function with respect to vehicle speed.

FIG. 17 is a diagram showing a membership function with respect to lateral acceleration.

FIG. 18 is a diagram showing a membership function with respect to an accelerator opening speed.

FIG. 19 is a diagram showing a membership function with respect to longitudinal acceleration.

FIG. 20 is a diagram showing a membership function with or without shift change.

FIG. 21 is a diagram showing a membership function with respect to a steering angular velocity.

FIG. 22 is a diagram showing a membership function with respect to a yaw rate.

FIG. 23 is a diagram showing a membership function with respect to a vehicle speed during brake operation.

FIG. 24 is a diagram showing a membership function when ABS is activated.

FIG. 25 is a diagram showing a membership function when TRC is activated.

FIG. 26 is a diagram showing a membership function with respect to the degree of in-phase during 4WS operation.

FIG. 27 is a diagram showing a membership function with respect to an engine speed.

FIG. 28 is a diagram showing a membership function with respect to system pressure.

FIG. 29 is a diagram showing a membership function with respect to a mode of a favorite slide switch.

FIG. 30 is a diagram showing a membership function with respect to a road surface friction coefficient.

FIG. 31 is a diagram showing a membership function with respect to oil temperature.

FIG. 32 is a map showing an example of changing each gain.

FIG. 33 is a continuation of the map shown in FIG. 32.

FIG. 34 is a map for obtaining a gain correction coefficient α according to a gain variation range.

FIG. 35 is an explanatory diagram when the target gain is applied to the map of FIG. 34.

FIG. 36 is an explanatory diagram for obtaining a gain correction coefficient α from the map of FIG. 34.

FIG. 37 is a diagram showing a membership function for target vehicle height control.

38 is an explanatory diagram in the case where the target gain is applied to the map of FIG. 37. FIG.

39 is an explanatory diagram for obtaining a control amount from the map of FIG. 37. FIG.

[Explanation of symbols]

 1 body 2FL left front wheel 2FR left rear wheel 2RL right front wheel 2RR right front wheel 3 fluid cylinder device 3FL fluid cylinder device for left front wheel 3FR fluid cylinder device for right front wheel 3RL fluid cylinder device for left rear wheel 3RR for right rear wheel Fluid cylinder device 3a Cylinder body 3b Piston 3c Hydraulic chamber 3d Piston rod 4 Communication passage 4a, 4b, 4c, 4d Branch communication passage 5 Gas spring 5FL Left front wheel gas spring 5FR Right front wheel gas spring 5RL Left rear wheel gas spring 5RR Gas spring for right rear wheel 5a, 5b, 5c, 5d Gas spring unit 5e Diaphragm 5f Gas spring gas chamber 5g Gas spring hydraulic chamber 8 Hydraulic pump 8a Discharge pipe 9 Proportional flow control valve 9a Pressure compensation valve 10 Fluid passage 12 Discharge pressure gauge 13 Liquid pressure sensor 14 Vehicle height displacement sensor 15a, 15b, 15c Vertical acceleration sensor 16 Lateral acceleration sensor 17 Control Unit 18 Steering Angle Sensor 19 Vehicle Speed Sensor 20 Drive Source 21 Hydraulic Pump for Power Steering Device 22 Accumulator 23F Front Wheel Side Pipe 23R Rear Wheel Side Pipe 23FL Left Front Wheel Side Pipe 23FR Right Front Wheel Side Pipe 23RL Left Rear Wheel Side Pipe 23RR Right Rear Wheel side piping 25a, 25b, 25c, 25d Orifice 26 Switching valve 28 Unload relief valve 29 Reserve tank 33 Open / close valve 34 Solenoid valve 35 Relief valve 36 Ignition key interlocking valve 37 Hydraulic pump relief valve 38 Return accumulator 41 Pouncing component calculator 42 Pitch component calculation unit 43 Roll component calculation unit 44 Bounce control unit 45 Pitch control unit 46 Roll control unit 50a, 50b, 50c, 50d Differentiator 51 Pitch component calculation unit 52 Roll component calculation unit 53 Switch control unit 54 roll control unit 61 pounce component calculation unit 62 pitch component calculation unit 63 roll component calculation unit 64 bounce control unit 65 pitch control unit 66 roll control unit 71 warp control unit 71a front wheel side hydraulic pressure ratio calculation unit 71b rear wheel side Hydraulic pressure ratio calculation unit 101 Accelerator speed sensor 102 Shift change sensor 103 Yaw rate sensor 104 Brake sensor 105 ABS sensor 105 106 TRC sensor 106 107 Wheel phase difference sensor 107 108 Engine speed sensor 108 109 System pressure sensor 109 110 Favorite slide switch mode sensor 110 111 Wheel speed sensor 111 112 Oil temperature sensor

Claims (4)

[Claims] 1. A suspension of a vehicle capable of changing suspension characteristics by controlling a supply amount and a discharge amount of a working fluid to and from a fluid cylinder device provided between an unsprung weight and an unsprung weight of each wheel. In the device, a motion state detecting means for detecting a plurality of motion states or road surface states of the vehicle, and a supply amount and discharge of the working fluid by fuzzy logic based on the amount of the motion state or road surface state detected by the motion state detecting means. A vehicle suspension device, comprising: a control unit that determines an amount. 2. The control means changes the control gain of a parameter relating to a running state of the vehicle by fuzzy logic based on the amount of the motion state or the road surface state detected by the motion state detecting means, thereby changing the control fluid of the working fluid. The vehicle suspension device according to claim 1, wherein the supply amount and the discharge amount are determined. 3. The parameter is at least one of a vehicle height displacement of a vehicle, a vehicle height displacement speed, a vertical acceleration, a twist, a lateral acceleration, and a pressure in the cylinder device. Item 3. The vehicle suspension device according to item 2. 4. The motion state or road surface state includes road surface roughness, road surface swell, vehicle speed, vehicle lateral acceleration, accelerator opening speed, vehicle longitudinal acceleration, presence of shift change, vehicle steering angular velocity, vehicle Yaw rate, whether the braking device is activated, whether the anti-brake skid device is activated, whether the traction control device is activated, the in-phase degree of the four wheels when the four-wheel steering device is activated, the engine speed, the system pressure, 4. The vehicle suspension apparatus according to claim 1, wherein the suspension switch is at least one of a mode of a favorite slide switch, a friction coefficient of a road surface, and an oil temperature.