JPH04278818A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To prevent slip of wheels well in the case that road surface friction coefficients of right and left wheels are different from each other by comprising a change means for changing control gain of a pitching sensor so that a ratio of the driving torque against a ground load of each wheel is less than a predetermined value. CONSTITUTION:In a suspension characteristic control device 90 for controlling a proportional flow quantity control valve, which controls supply and exhaust of the working fluid to a fluid cylinder device of each wheel, a mode selecting means 91 selects mode on the basis of the lateral acceleration and the speed. A torque computing means 94 computes the driving torque of each wheel on the basis of the engine output detecting means and the brake pressure detecting signal. Furthermore, a control gain change means 95 is provided to compute ground load of each wheel on the basis of the speed and the lateral acceleration, and a value of the gain of a control system is changed for setting so that a ratio of the described driving torque against the ground load of each wheel is less than a predetermined value in response to the operation condition.

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 that can prevent wheel slippage while controlling suspension characteristics as desired. It is.

0002

[Prior Art] Conventionally, a suspension device called a passive suspension is composed of a hydraulic shock absorber and a damper unit made of a spring such as a coil spring. Although it is possible to change the characteristics to some extent, the range is small and, in practice, the suspension characteristics in passive suspension devices are set uniformly.

On the other hand, in recent years, a fluid cylinder device is provided between the sprung mass and the unsprung mass, and the desired suspension characteristics are achieved by controlling the amount of working fluid supplied to and discharged from the fluid cylinder device. A suspension device called an active suspension that can be modified as follows has been proposed (for example, Japanese Patent Publication No. 59-14365, Japanese Patent Application Laid-Open No. 63-130418, etc.).

In general, there are three types of vehicle vibration: bounce, pitch, and roll. Such active suspension systems are equipped with a fluid cylinder device for each wheel to handle these three types of vehicle vibration. On the other hand, in order to improve riding comfort and running stability, the supply and discharge of working fluid to the fluid cylinder device of each wheel is controlled at a predetermined control gain that is set and controlled according to the driving state of the vehicle. It is controlled by controlling the opening degree of the flow control valve of each wheel.

[0005]

[Problems to be Solved by the Invention] As described above, the active suspension system is designed to improve the riding comfort and running stability of each wheel in response to the three types of vibrations of the vehicle, depending on the driving condition of the vehicle. In order to control the supply and discharge of working fluid to the fluid cylinder device using predetermined control gains, the vehicle is equipped with a suspension characteristic control device that detects the driving state of the vehicle and changes the settings of each control gain. In conventional suspension characteristic control devices, the suspension characteristics are controlled to maintain the desired steering characteristics and to suppress the torsion of the vehicle body. However, there was a problem in that there was a difference in torque between the left and right wheels, which could cause one of the wheels to slip.

[0006]

OBJECTS OF THE INVENTION The present invention has a fluid cylinder device for each wheel between the sprung mass and the unsprung mass of the vehicle, and adjusts the control gain of the suspension characteristics according to the driving condition of the vehicle. a suspension characteristic control device for setting and controlling the suspension characteristics, and a displacement detection means for detecting displacement of the vehicle,
Based on the detection result of the displacement detection means, the supply amount and discharge amount of the working fluid to the fluid cylinder device are controlled by a predetermined control gain set and controlled by the suspension characteristic control device so as to cancel the displacement of the vehicle. An object of the present invention is to provide a suspension device for a vehicle that can prevent wheel slippage while controlling suspension characteristics as desired.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to control the pitching center so that the ratio of the drive torque to the ground load of each wheel is equal to or less than a predetermined value M, depending on the driving condition of the vehicle. This is achieved by providing a control gain changing means for changing the setting of the control gain.

In a preferred embodiment of the present invention, the control gain changing device is configured to change the setting of the control gain so that the predetermined value M becomes smaller in an acceleration state. In a further preferred embodiment of the present invention, the control gain changing device changes the setting of the control gain so that the predetermined value M becomes smaller when the vehicle speed is below a predetermined value and is in an acceleration state. is configured to do so.

[0009]

According to the present invention, the suspension characteristic control device sets the control gain so that the ratio of the drive torque to the ground load of each wheel is equal to or less than the predetermined value M, depending on the driving state of the vehicle. Since it is equipped with a control gain changing means, in driving conditions where it is not necessary to emphasize steering characteristics, the control gain setting is changed in order to prevent wheel slip, and the working fluid is supplied to the fluid cylinder device. By controlling the amount and displacement, the ground load of wheels that are prone to slip is increased, preventing wheel slip. On the other hand, in driving conditions where steering characteristics are important, desired steering characteristics can be achieved. Since the control gain is set and the amount of working fluid supplied to and discharged from the fluid cylinder device is controlled so as to obtain It becomes possible.

According to a preferred embodiment of the present invention, the control gain changing means changes the setting of the control gain so that the predetermined value M becomes smaller in the acceleration state where slip is more likely to occur, so that the wheel Slips can be more reliably prevented. In a further preferred embodiment of the present invention, the control gain is set so that the predetermined value M becomes smaller in a low vehicle speed acceleration state in which steering characteristics are not so important and slip is likely to occur. Therefore, wheel slipping can be more reliably prevented while controlling the suspension characteristics as desired.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the accompanying drawings. FIG. 1 is an overall schematic diagram of a vehicle including a vehicle suspension device according to an embodiment of the present invention. Although only the left side of the vehicle body 1 is illustrated in FIG. 1, the right side of the vehicle body 1 is similarly configured. In FIG. 1, fluid cylinder devices 3, 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, respectively. A hydraulic chamber 3c is formed within each fluid cylinder device 3 by a piston 3b fitted into 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 main body 3a is
It is connected to the left front wheel 2FL or the left rear wheel 2RL.

The hydraulic chamber 3c of each fluid cylinder device 3 communicates with a gas spring 5 through a communication passage 4, and each gas spring 5 is connected to a gas chamber 5f and a hydraulic chamber 5 through a diaphragm 5e.
The hydraulic chamber 5g communicates with the hydraulic chamber 3c of the fluid cylinder device 3 through the communication passage 4 and the piston 3b of the fluid cylinder device 3. A fluid passage 10 connecting the hydraulic pump 8 and each fluid cylinder device 3 so as to be able to supply fluid has a flow rate of fluid supplied to the fluid cylinder device 3 and a flow rate of fluid discharged from the fluid cylinder device 3. Proportional flow control valves 9, 9 are respectively provided to control the flow rate.

The hydraulic pump 8 is provided with a discharge pressure gauge 12 for detecting the discharge pressure of the fluid, and also has hydraulic pressure sensors 13, 1 for detecting the hydraulic pressure in the hydraulic chamber 3c of each fluid cylinder device 3.
3 is provided. Furthermore, the cylinder stroke amount of each fluid cylinder device 3 is detected, and each wheel 2FL, 2RL is
Vehicle height displacement sensors 14, 14 are provided to detect the vertical displacement of the vehicle body, that is, the vehicle height displacement, and also detect the vertical acceleration of the vehicle, that is, the wheels 2FL,
Vertical acceleration sensors 15, 15, 15 for detecting the vertical acceleration on the spring of 2RL are installed above the left and right front wheels 2FL, 2FR and one each on the vehicle body width of the left and right rear wheels on a substantially horizontal plane of the vehicle. A lateral acceleration sensor 16 is provided at the center of gravity of the vehicle body 1 to detect acceleration applied in the lateral direction of the vehicle, and a steering angle sensor 18 and a vehicle speed sensor 16 are provided at the center of gravity of the vehicle body 1. A sensor 19 is provided respectively.

Discharge pressure gauge 12, hydraulic pressure sensors 13, 13, vehicle height displacement sensors 14, 14, vertical acceleration sensors 15, 15, 15, lateral acceleration sensor 16, steering angle sensor 18, and vehicle speed sensor 19 provided in this manner The detection signals are input to the control unit 17 which has a CPU etc. inside, and the control unit 17 performs calculations according to a predetermined program based on these detection signals, and controls the proportional flow control valves 9, 9. , as desired,
The suspension characteristics are configured to be variably controlled.

FIG. 2 is a circuit diagram of a hydraulic circuit that supplies fluid from the hydraulic pump 8 to the fluid cylinder devices 3FR, 3FL, 3RR, and 3RL, or discharges fluid from these. In FIG. 2, the hydraulic pump 8 is driven by a drive source 20.
An accumulator 22 is connected in parallel to a hydraulic pump 21 for a power steering device driven by the hydraulic pump 21, and is connected to a discharge pipe 8a for discharging fluid from the hydraulic pump 21 to the fluid cylinder devices 3, 3, 3, 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. The front wheel side piping 23F branches into a left front wheel side piping 23FL and a right front wheel side piping 23FR on the downstream side of the branching part with the rear wheel side piping 23R, and the left front wheel side piping 23FL and the right front wheel side piping 23FR are, respectively, It communicates with the hydraulic chambers 3c, 3c of the fluid cylinder device 3FL for the left front wheel and the fluid cylinder device 3FR for the right front wheel. Similarly, the rear wheel side pipe 23R is connected to the left rear wheel side pipe 23R on the downstream side of the branching part.
3RL and right rear wheel side piping 23RR, and the left rear wheel side piping 23RL and right rear wheel side piping 23RR are used to supply fluid to the fluid cylinder device 3RL for the left rear wheel and the fluid cylinder device 3RR for the right rear wheel, respectively. It communicates with the pressure chambers 3c, 3c.

These fluid cylinder devices 3FL, 3FR
, 3RL and 3RR have gas springs 5FL and 5, respectively.
FR, 5RL and 5RR are connected, and each gas spring 5FL, 5FR, 5RL and 5RR is composed of four gas spring units 5a, 5b, 5c, 5d, and these gas spring units 5a, 5b, 5c, 5d are the corresponding fluid cylinder devices 3FL, 3FR, 3, respectively.
Branch communication passages 4a, 4b, 4c, 4d are connected to the communication passage 4 communicating with the hydraulic pressure chambers 3c, 3c, 3c, 3c of RL and 3RR.
connected by. In addition, each gas spring 5FL, 5F
The branch communication paths 4a, 4b, 4c and 4d of R, 5RL and 5RR have orifices 25a, 25b and 2, respectively.
5c and 25d are provided, and these orifices 25
Damping action of a, 25b, 25c, 25d and gas spring 5
The high-frequency vibrations applied to the vehicle are reduced by the buffering effect of the gas sealed in the gas chambers 5f of FL, 5FR, 5RL, and 5RR.

Each gas spring 5FL, 5FR, 5RL, 5R
Gas spring units 5a, 5b, 5c, 5d forming R
A first gas spring unit 5a provided at a position closest to the hydraulic pressure chambers 3c, 3c, 3c, and 3c of each fluid cylinder device 3FL, 3FR, 3RL, and 3RR, and a second gas spring unit adjacent thereto. 5b, the passage area of the communication passage 4 is adjusted by taking an open position where the communication passage 4 is opened and a closed position where the passage area is narrowed. A switching valve 26 is provided to switch the damping force of the 5RR into two stages. FIG. 2 shows the switching valve 26 in the open position.

An unload relief valve 28 is connected to the discharge pipe 8 a of the hydraulic pump 8 near the upstream side of the connection portion of the accumulator 22 . is the predetermined upper limit,
For example, when the pressure is above 160 kgf/cm2, the switch is switched to the open position and the oil discharged from the hydraulic pump 8 is directly returned to the reserve tank 29, while when the pressure is below a predetermined lower limit, for example 120 kgf/cm2, the switch is switched to the closed position. It is controlled so that oil is supplied to the accumulator 22 and the accumulated pressure value of the hydraulic pressure of the accumulator 22 is maintained at a predetermined value. In this way, oil is supplied to each fluid cylinder device 3 by storing oil in the accumulator 22, which is maintained 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, right front wheel, left rear wheel, and right rear wheel are constructed in the same way, only the hydraulic circuit for the left front wheel will be explained below, and the rest will be explained as follows. Omit this. The proportional flow control valve 9 is a three-way valve, with a closed position where all ports are closed, a supply position where the left front wheel side piping 23FL is opened to the hydraulic pressure supply side, and a fluid cylinder device 3 of the left front wheel side piping 23FL connected to the return piping 32. It can take three positions with the communicating discharge position. FIG. 2 shows the proportional flow control valve 9 in the closed position. Further, the proportional flow control valve 9 includes pressure compensating valves 9a, 9a, and these pressure compensating valves 9a, 9a allow the fluid cylinder device 3 to be controlled when the proportional flow control valve 9 is in the supply position or the discharge position. Hydraulic chamber 3
The hydraulic pressure in c is maintained at a predetermined value.

A pilot pressure-responsive opening/closing valve 33 is provided on the fluid cylinder device 3 side of the proportional flow rate control valve 9 and is capable of opening and closing the left front wheel side piping 23FL. This on-off valve 33
When the solenoid valve 34 that guides the hydraulic pressure of the left front wheel side piping 23FL on the hydraulic pump 8 side of the proportional flow control valve 9 is opened, the solenoid valve 34 is opened.
is introduced as a pilot pressure, and when this pilot pressure is equal to or higher than a predetermined value, the on-off valve 33 opens the left front wheel side piping 23FL, and the proportional flow control valve 9 controls the flow rate of fluid to the fluid cylinder device 3. is possible.

Furthermore, the hydraulic chamber 3c of the fluid cylinder device 3
A relief valve 35 that opens when the hydraulic pressure in the chamber increases abnormally and returns the fluid in the hydraulic pressure chamber 3c to the return pipe 32, is connected to the discharge pipe 8a of the hydraulic pump 8 near the downstream side of the connection part of the accumulator 22, Open when the ignition is turned off,
The ignition key interlocking valve 36 returns the oil stored in the accumulator 22 to the reserve tank 29 and releases the high pressure state in the accumulator 22. a return accumulator 38 that is connected to a hydraulic pump relief valve 37 that returns oil to the reserve tank 29 and lowers the oil discharge pressure of the hydraulic pump 8 and a return pipe 32, and that performs a pressure accumulation function when fluid is discharged from the fluid cylinder device 3; 38 are provided respectively.

FIGS. 3 to 10 are block diagrams of the fluid control amount calculation device 100 provided in the control unit 17. In FIGS. 3 to 10,
The fluid control amount calculation device 100 provided in the control unit 17 according to this embodiment uses vehicle height displacement signals XFR, X
A control system A that controls the vehicle height to the target vehicle height based on FL, XRR, and XRL, and vehicle height displacement signals XFR, XFL, and XR.
Vehicle height displacement speed signal YFR obtained by differentiating R and XRL
, YFL, YRR, and YRL, a control system B that suppresses the vehicle height displacement speed, and three vertical acceleration sensors 15.
, 15 and 15, the control system C aims to reduce the vertical vibration of the vehicle based on the vertical acceleration signals GFR, GFL and GR.
, a control system D that calculates and suppresses the torsion of the vehicle body based on the pressure signals PFR, PFL, PRR, PRL of the hydraulic pressure sensors 13, 13, 13, 13 of each wheel, and a control system D that suppresses the torsion of the vehicle body; It is comprised of a control system E that aims to reduce vibrations in the lateral direction of the vehicle based on the lateral acceleration detection signal GL.

The control system A includes vehicle height sensors 14 for each wheel;
Vehicle height displacement signal XFR detected by 14, 14, 14
, XFL, XRR, and XRL to cut noise.
Low pass filters 40a, 40 that cut high frequency components
b, 40c, and 40d are provided, and a low pass filter 40
Outputs XFR of the vehicle height sensors 14, 14 of the left and right front wheels 2FL, 2FR with high frequency components cut by a, 40b
, XFL and low-pass filter 40c.
, 40d, the output XRR of the vehicle height sensors 14, 14 of the left and right rear wheels 2RL, 2RR with high frequency components cut off.
, a pitch component calculation unit 42 that calculates the pitch component of the vehicle by subtracting the added value of the outputs XRR and XRL of the vehicle height sensors 14 and 14, and a left and right front wheel 2FL.
, 2FR vehicle height sensor 14, 14 output XFR, XFL
The difference XFR-XFL and the output XRR of the vehicle height sensors 14, 14 of the left and right rear wheels 2RL and 2RR, and the difference
A roll component calculating section 43 is provided that calculates a roll component of the vehicle by adding R-XRL.

The control system A also includes a bounce component calculation section 4.
The bounce component of the vehicle and the target average vehicle height TH calculated in step 1 are input, and the bounce control section 44 calculates the amount of fluid supplied to the fluid cylinder device 3 of each wheel in bounce control based on the gain KB1, and the pitch component calculation Section 42
The pitch component of the vehicle calculated in is input, and the gain KP is
1, the roll component and target roll displacement amount TR calculated by the pitch control unit 45 and roll component calculation unit 43 that calculate the amount of fluid supplied to the fluid cylinder device 3 of each wheel in pitch control are input, and the gain KRF1
.

In this way, the control variables calculated by the bounce control section 44, the pitch control section 45, and the roll control section 46 are reversed in sign for each wheel. 14, the vehicle height displacement signals XFR, , control flow signals QFR1, QFL1, QRR1, to the proportional flow rate control valves 9 of each wheel in the control system A,
QRL1 is obtained.

Here, each low-pass filter 40a, 40
Between b, 40c, 40d and the bounce calculation section 41, pitch calculation section 42, and roll calculation section 43, a dead band device 4 is provided.
7a, 47b, 47c, and 47d are provided, and vehicle height displacement signals XFR, , XRL is the preset dead zone XH , XH , XH , XH
These vehicle height displacement signals XFR,
XFL, XRR, and XRL are output to a bounce calculation section 41, a pitch calculation section 42, and a roll calculation section 43.

Control system B includes vehicle height sensors 14, 14, 14
and 14, low-pass filters 40a and 4
0b, 40c, and 40d, the vehicle height displacement signals XFR, XFL, XRR, and XRL with high frequency components cut are differentiated, and vehicle height displacement speed signals YFR and YF are obtained according to the following equations.
Differentiators 50a, 50b that calculate L, YRR, and YRL,
50c and 50d.

Y=(Xn-Xn-1)/T where,
n is the amount of vehicle height displacement at time t, Xn-1 is the amount of vehicle height displacement at time t-1, and T is the sampling time. Furthermore, the control system B calculates the left and right rear wheels 2RL, the left and right rear wheels 2RL, from the sum of the vehicle height displacement speed signals YFL and YFR of the left and right front wheels 2FL and 2FR, respectively.
A pitch component calculation unit 51 that calculates the pitch component of the vehicle by subtracting the added value of the vehicle height displacement speed signals YRL and YRR on the 2RR side, and vehicle height displacement speed signals YFL and YFR on the left and right front wheels 2FL and 2FR side. The difference YFR-YFL and the vehicle height displacement speed signal YRL on the left and right rear wheels 2RL and 2RR side,
A roll component calculating section 52 is provided that calculates a roll component of the vehicle by adding the difference YRR - YRL.

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

Pitch control section 53 and roll control section 54
Each control amount calculated in is further reversed in sign for each wheel.
c, vehicle height displacement speed signal YFR calculated by 50d,
YFL, YRR, and YRL are reversed so that their positive and negative values are opposite, and then the pitch and roll control amounts for each wheel are added, respectively, and sent to the proportional flow control valve 9 of each wheel in control system B. Flow rate signal QFR2,
QFL2, QRR2, and QRL2 are obtained.

The control system C includes low-pass filters 60a, 6
0b and 60c, a bounce component calculation unit 61 calculates a bounce component of the vehicle by adding the vertical acceleration detection signals GFR, GFL, and GR detected by the vertical acceleration sensors 15, 15, and 15 whose high frequency components have been cut; The sum of 1/2 of the outputs of the vertical acceleration sensors 15, 15 installed above the left and right front wheels 2FR, 2FL (GFR+GFL
)/2, a pitch component calculation unit 62 calculates the pitch component of the vehicle by subtracting the output GR of the vertical acceleration sensor 15 provided at the center of the left and right rear wheels in the vehicle width direction; Calculation of the bounce component calculated by the roll component calculation unit 63 and the bounce component calculation unit 61, which calculates the roll component of the vehicle by subtracting the output GFL of the vertical acceleration sensor 15 on the left front wheel side from the output GFR of the acceleration sensor 15. The value is input, and based on the gain KB3, the pitch component calculation value calculated by the bounce control section 64 which calculates the control amount of fluid to each proportional flow rate control valve 9 in bounce control and the pitch component calculation section 62 is calculated. input, gain K
Proportional flow control valve 9 in pitch control based on P3
The calculated value of the roll component calculated by the pitch control unit 65 and the roll component calculation unit 63, which calculates the amount of fluid to be controlled to the pitch control unit 65, and the roll component calculation unit 63 are input, and based on the gain KR3, the flow rate control valve 9 in the roll control is inputted. It is composed of a roll control section 66 that calculates a fluid control amount.

In this way, the control amounts calculated by the bounce control section 64, pitch control section 65, and roll control section 66 are reversed for each wheel, and then the bounce and pitch for each wheel are and each control amount of the roll are added, and flow rate signals QFR3, QFL3, QRR3 and QRL3 outputted from the control system C to each proportional control valve 9 are obtained.

Note that low-pass filters 60a, 60b, and 60c for cutting high frequency components, a bounce component calculation section 61, a pitch component calculation section 62, and a roll component calculation section 63
There are dead band devices 67a, 67b, 67 between them, respectively.
c are provided, and from the vertical acceleration sensors 15, 15 and 15, low pass filters 60a, 60b, 60c,
Vertical acceleration signals GFR and GF are input through 60d.
L, GR are preset dead zones XG,
Only when G,
, is output to the pitch component calculation section 62 and the roll component calculation section 63.

The control system D receives hydraulic pressure detection signals PFL and PFR detected by the hydraulic pressure sensors 13 and 13 of the fluid cylinder devices 3 of the left and right front wheels 2FL and 2FR, and their high frequency components are passed through the low-pass filters 70a and 2FR. After being cut by 70b, the difference in hydraulic pressure between the hydraulic pressure chambers 3c, 3c of the fluid cylinder device 3 of the left and right front wheels 2FR, 2FL, PFR-P.
Ratio Pf of FL and these added values PFR+PFL =
(PFR-PFL)/(PFR+PFL) is calculated, and if the calculated hydraulic pressure ratio Pf is -ωL < Pf < ωL with respect to the threshold hydraulic pressure ratio ωL, the calculated hydraulic pressure ratio Pf is Output as is, and on the other hand, Pf <-
When ωL or Pf > ωL, the front wheel side hydraulic pressure ratio calculating section 71a outputs the threshold hydraulic pressure ratio -ωL or ωL, and similarly, the left and right rear wheels 2RL,
The hydraulic pressure detection signals PRL and PRR detected by the hydraulic pressure sensors 13 and 13 of the 2RR fluid cylinder device 3 are input, and their high frequency components are passed through the low-pass filters 70c and 70d.
After being cut, the left and right rear wheels 2RR and 2RL
The difference P between the hydraulic pressures of the hydraulic chambers 3c and 3c of the fluid cylinder device 3
It has a rear wheel hydraulic pressure ratio calculating section 71b that calculates the ratio PR = (PRR-PRL)/(PRR+PRL) of RR-PRL and their added value PRR+PRL, and calculates the ratio Pr of the rear wheel hydraulic pressure. After multiplying by a predetermined value based on the gain ωF,
A warp control section 71 is provided to subtract this from the front wheel side hydraulic pressure ratio Pf, and the output of the warp control section 71 is multiplied by a predetermined value using a gain ωA, and then on the front wheel side, using a gain ωC Multiply it by a predetermined value, then invert one of the left and right wheels so that the controlled amount of fluid supplied to each wheel is opposite in positive and negative, and further increase the ratio of the drive torque to the ground load of each wheel to a predetermined value, which will be described later. Gains ωTFR, ωTFL, ωTRR determined to be less than or equal to the values
, ωTRL are multiplied by the flow rate signals QFR4, QFL4, Q to each proportional flow control valve 9 in the control system D.
RR4 and QRL4 are obtained.

Furthermore, the control system E includes a lateral acceleration sensor 16
A lateral acceleration detection signal applied in the lateral direction of the vehicle detected by is further multiplied by a predetermined value based on the gain AGF, and then the fluid supply control amount for the left front wheel 2FL is reversed so that the fluid supply control amount for the left and right wheels is opposite in sign, and the other , for the left and right front wheels 2RL and 2RR, the fluid supply control amount for the left rear wheel 2FL is reversed so that the positive and negative fluid supply control amounts for the left and right wheels are reversed, and each proportional flow rate in the control system E is Flow rate signals QFR5, QFL5, QRR5, QRL5 to control valve 9
is obtained.

Each of the control systems A and B obtained as described above
, C, D, and E to each proportional flow control valve 9 are added for each wheel, and further,
For L and 2FR, the gain AF is multiplied and the total flow signals QFR, QFL, and
QRR and QRL are obtained. Tables 1, 2, 3, and 4 are used in each of the control systems A, B, C, D, and E stored in the suspension characteristic control device provided in the control unit 17. This shows an example of a control gain reference map, and seven modes are set depending on the driving state. These modes are, respectively, in the operating state shown in FIG.
It is now selected.

That is, Tables 1 to 4 and FIG.
1, mode 1 is the value of each control gain for 60 seconds after the engine has stopped, and mode 2 is the ignition switch is on, but the vehicle is stopped,
In mode 3, the value of each control gain in a state where the vehicle speed is zero is determined when the vehicle lateral acceleration GL is 0.3 or less and the vehicle speed is 30 km/h or less, or when the vehicle lateral acceleration GL is 0.3 or less. 3 and the vehicle speed is 40 km/h or less. Indicates the value of the control gain to be selected instead of mode 5 when the directional acceleration GL is 0.3 or less and the vehicle speed exceeds 30 km/h and is in a medium-speed slow turning state of 60 km/h or less,
When the vehicle speed exceeds 60 km/h, the driver automatically switches to Mode 5 even if the reverse roll mode is selected. In addition, mode 5 indicates the value of each control gain in a driving state where the vehicle speed exceeds 60 km/h and is below 80 km/h, and in a slow turning state where the lateral acceleration GL of the vehicle is 0.2 or less. 6 is a vehicle in which the lateral acceleration GL exceeds 0.3, the vehicle speed exceeds 40 km/h and is 60 km/h or less, or the lateral acceleration GL exceeds 0.2, and
The value of each control gain when the vehicle speed is over 60 km/h and under 80 km/h, mode 7 is when the vehicle speed is 80 km/h or less.
It shows the value of each control gain in a driving state exceeding km/h.

In Tables 3 and 4, QMAX
indicates the maximum flow rate control amount supplied to the proportional flow rate control valve 9 of each wheel, and PMAX indicates the maximum pressure in the hydraulic pressure chamber 3c of the fluid cylinder device 3, It is set so that fluid does not flow back into the accumulator 22 from the pressure chamber 3c, and furthermore, the PMIN
indicates the minimum pressure in the hydraulic pressure chamber 3c of the fluid cylinder device 3, and is designed to prevent the pressure in the hydraulic pressure chamber 3c of the fluid cylinder device 3 from decreasing excessively and causing the gas spring 5 to fully expand and be damaged. is set to .

In Tables 1 to 4, except for mode 4, each control gain is set such that the larger the mode number, the more suspension control is performed with emphasis on running stability. FIG. 12 is a block diagram of a suspension characteristic control device 90 provided within the control unit 17.

In FIG. 12, the suspension characteristic control device 90 receives the lateral acceleration GL applied to the lateral direction of the vehicle detected by the lateral acceleration sensor 16 and the vehicle speed signal detected by the vehicle speed sensor 19, and inputs a previously stored diagram. According to the mode map shown in 6, the lateral acceleration G
A mode selection means 91 selects a mode based on L and vehicle speed V, an engine output detection signal from an engine output detection means 92 and a brake pressure detection signal of each wheel detected by each wheel brake pressure detection means 93FR, 93FL, 93RR, 93RL. A brake pressure detection signal is input, and based on these input signals, the drive torque TFR, TFL,
A torque calculating means 94 that calculates TRR and TRL, a vehicle speed signal detected by the vehicle speed sensor 19, and a detection signal of the lateral acceleration GL applied to the lateral direction of the vehicle detected by the lateral acceleration sensor 16 are input, and each wheel The hydraulic pressure chambers 3c, 3c, 3c, 3 of each fluid cylinder device 3, 3, 3, 3 detected by the hydraulic pressure sensors 13, 13, 13, 13
The hydraulic pressure detection signal in c is input, and based on the input hydraulic pressure detection signal, the ground load WFR, WFL, WR of each wheel is calculated.
R, WRL are calculated, and the drive torques TFR, TFL, TRR, and TRL of each wheel are input from the torque calculation means 94.
According to the ground load of each wheel WFR, WFL, WRR
, drive torque TFR, TFL, TRR for WRL,
The gains ωTFR and ωTFL in the control system D are adjusted so that the ratio of TRL is equal to or less than a predetermined value depending on the operating state.
, ωTRR, ωTRL, a mode signal is input from the mode selection means 91, and a control gain change signal is input from the control gain change means 95, respectively.
According to these input signals and the control gain reference maps shown in Tables 1 to 4 stored in advance,
The fluid control amount calculation device 100 includes a control gain output means 96 that selects each control gain and outputs a control gain signal.

In the suspension characteristic control device 90 configured as described above, the mode selection means 91 selects
Based on the lateral acceleration GL and the vehicle speed V, a mode is selected according to the mode map shown in FIG.
The mode signal is output to the control gain output means 96, and the control gain output means 96 selects each control gain according to the mode signal and the reference map of control gains shown in Table 1 stored in advance to A control gain signal is output to the control amount calculation device 100, and the gains ωTFR, ωTFL, ωTRR, ω in the control system D
The value of TRL is changed by the control gain changing means 95 according to the flowchart shown in FIG. The control gain output means 96 is the control gain change means 9
Based on the control gain change signal input from 5, the gains ωTFR, ωTFL, ωTRR in the control system D
, ωTRL to the fluid control amount calculation device 100.

In FIG. 13, first, the engine output detection signal from the engine output detection means 92 and the brake pressure detection means 93FR, 93FL, 93RR, 93 for each wheel are detected.
The brake pressure detection signal of each wheel detected by RL is input to the torque calculation means 94, and the drive torque TFR of each wheel is inputted to the torque calculation means 94.
, TFL, TRR, and TRL are calculated. Next, the vehicle speed signal V detected by the vehicle speed sensor 19, the lateral acceleration GL detected by the lateral acceleration sensor 16, and each fluid cylinder device 3, 3, detected by the hydraulic pressure sensor 13, 13, 13, 13 of each wheel. 3, 3 hydraulic chambers 3c, 3c, 3
The hydraulic pressure detection signals in c and 3c are detected by the control gain changing means 95.
Based on these input signals, the control gain changing means 95 changes the ground loads WFR, WFL, and W of each wheel.
Calculate RR, WRL, and vehicle acceleration α.

Furthermore, the control gain changing means 95 determines whether the vehicle speed V is less than or equal to a predetermined value V0, for example, less than or equal to 10 km/h. When the result is YES, that is, when the vehicle speed V is less than or equal to the predetermined value V0, the vehicle is in a stopped state or in a low-speed running state, and it is recognized that the driving state does not require emphasis on steering characteristics. The control gain changing means 95 further adjusts the acceleration α of the vehicle to a predetermined value α0.
It is determined whether or not the above is true, that is, whether the vehicle is in an acceleration state where slipping is likely to occur, and if YES, that is,
When the vehicle is in a stopped state or in a low-speed running state and in an accelerated state where slipping is likely to occur, the control gain changing means 95 changes the ground load WFR, WF of each wheel.
Drive torque TFR, TFL for L, WRR, WRL
, TRR, and TRL are set to the gains ωTFR, ωTFL, and
The settings of ωTRR and ωTRL are changed and a control gain change signal is output to the control gain output means 96.

On the other hand, when the answer is NO, that is, the vehicle is stopped or running at low speed, which is considered to be a driving state in which there is no need to emphasize steering characteristics, but the vehicle is in an accelerated state where slipping is likely to occur. When it is determined that there is no ground load WF of each wheel, the control gain changing means 95 changes the ground load WF of each wheel.
Drive torque TFR for R, WFL, WRR, WRL
The gains ωTFR, ωTFL, ωTRR, ωT in the control system D are set so that the ratio of , TFL, TRR, and TRL is equal to or less than a predetermined value M2 that is larger than the predetermined value M1.
The setting of RL is changed and a control gain change signal is output to the control gain output means 96.

On the other hand, when the vehicle speed V is below the predetermined value V0, it is recognized that the vehicle is running at a medium speed or higher, and the steering characteristics are controlled depending on the driving state. Since it is determined whether or not the requirement of preventing slips can be met, the control gain changing means 95 further adjusts the lateral acceleration GL to a predetermined value GL.
It is determined whether it is 0 or more, for example, 4G or more.

As a result, when the vehicle is in the NO state, that is, the vehicle is running at medium speed or higher but is not in a high turning state, it is possible to achieve both the control of steering characteristics and the prevention of slippage to a certain extent. , control gain changing means 9
5 is the ground load of each wheel WFR, WFL, WRR, WR
Drive torque TFR, TFL, TRR, TRL for L
The gains ωTFR and ωTF in the control system D are adjusted such that the ratio of the gains ωTFR and ωTF
The settings of L, ωTRR, and ωTRL are changed, and a control gain change signal is output to the control gain output means 96.

On the other hand, if YES, it is recognized that the vehicle is running at a medium speed or higher and is in a high turning state, so it is essential to control the steering characteristics as desired, and therefore the control gain The changing means 95 changes the gain in the control system D so that the ratio of the driving torques TFR, TFL, TRR, TRL to the ground loads WFR, WFL, WRR, WRL of each wheel becomes equal to or less than a predetermined value M4 which is larger than the predetermined value M3. ωTFR, ωTFL, ωTRR
, ωTRL and outputs a control gain change signal to the control gain output means 96.

As described above, according to this embodiment, depending on the driving condition of the vehicle, it is determined whether wheel slipping should be preferentially prevented, steering characteristics should be preferentially controlled, or both should be balanced. The control gain changing means 95 determines whether the gains ωTFR and ωT in the control system D are
Since the settings of FL, ωTRR, and ωTRL are changed and a control gain change signal is output to the control gain output means 96, it is possible to effectively prevent wheel slip while controlling the suspension characteristics as desired. Can be done.

FIG. 14 shows another example of the mode map, and mode 1, mode 2 and mode 7 are shown in FIG.
1, but mode 4, which is a reverse roll mode, is not set, and when the vehicle speed is 40 km/h or less, mode 3 is selected and the vehicle speed is 40 km/h or less.
When the lateral acceleration GL is 0.2 or less, mode 5 is set to 0.
When the number exceeds 2, mode 6 is selected.

[0050] The present invention is not limited to the above embodiments, but various modifications can be made within the scope of the invention described in the claims, and these are also included within the scope of the present invention. Needless to say, it is. For example, in the embodiment described above, the vehicle suspension system includes the gas spring 5, but the present invention can also be applied to a so-called full active suspension system that does not include the gas spring 5.

Further, in the above embodiment, when the vehicle is in a stopped state or in a low speed running state and in a high acceleration state where the acceleration α is the predetermined value α0 or more, the ground load WFR of each wheel is Gains ωTFR, ωTFL, ωTRR, ωT in control system D are set so that the ratio of driving torques TFR, TFL, TRR, TRL to WFL, WRR, WRL is equal to or less than the smallest predetermined value M1.
RL, but when it is determined that the vehicle is stopped or running at low speed, the ground load WFR of each wheel is changed without determining whether the vehicle is accelerating or not. Gains ωTFR, ωTFL, ωTRR, ωTR in control system D are set so that the ratio of driving torques TFR, TFL, TRR, TRL to WFL, WRR, WRL is equal to or less than a predetermined value M0 smaller than M3.
The setting of L may be changed.

Furthermore, in the embodiment, the engine output detection signal from the engine output detection means 92 and the brake pressure detection means 93FR, 93FL, 93R for each wheel are
Based on the brake pressure detection signal of each wheel detected by R, 93RL, the drive torque TFR, TFL, TR of each wheel is determined.
R and TRL are calculated, but when the vehicle is equipped with a traction control system, the drive torques TFR, TFL, and TR of each wheel are calculated based on the traction control signal.
R and TRL may also be calculated.

Furthermore, it goes without saying that the present invention can be applied to any of front wheel drive vehicles, rear wheel drive vehicles, and four wheel drive vehicles. Furthermore, although the fluid control amount is calculated according to the gains shown in Tables 1 to 4, Tables 1 to 4 are only examples, and various changes may be possible. Needless to say.

Furthermore, in the present invention, each means does not necessarily mean a physical means, and the present invention also includes the case where the function of each means is realized by software, and two or more means The present invention encompasses cases where a function is realized by one physical means, and cases where a function of one means is realized by two or more physical means.

[0055]

According to the present invention, each wheel has a fluid cylinder device between the unsprung weight and the unsprung weight of the vehicle, and the suspension characteristics can be adjusted according to the driving condition of the vehicle. The suspension characteristic control device includes a suspension characteristic control device that sets and controls a control gain, and a displacement detection device that detects displacement of the vehicle, and a predetermined control gain that is set and controlled by the suspension characteristic control device based on the detection result of the displacement detection device. In an active suspension device that controls the supply and discharge amount of working fluid to a fluid cylinder device so as to cancel the displacement of the vehicle, it is possible to prevent wheel slipping while controlling suspension characteristics as desired. It becomes possible to provide a suspension device for a vehicle.

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

[Table 3]

[0059]

[Table 4]

[Brief explanation of the drawing]

FIG. 1 is an overall schematic diagram 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 supplies fluid from a hydraulic pump to a fluid cylinder device or discharges fluid therefrom.

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

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

FIG. 11 is a drawing showing an example of a mode map of a suspension device according to an embodiment of the present invention.

FIG. 12 is a block diagram of a suspension characteristic control device for a suspension device according to an embodiment of the present invention.

FIG. 13 is a flowchart showing an example of a control gain setting change by a control gain change means provided in the suspension characteristic control device of the suspension device according to the embodiment of the present invention.

FIG. 14 is a drawing showing another example of a mode map.

[Explanation of symbols]

1 Vehicle 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 Right rear wheel Fluid cylinder device 3a
Cylinder body 3b Piston 3c Hydraulic pressure chamber 3d Piston rod 4 Communication passages 4a, 4b, 4c, 4d Branch communication passage 5 Gas spring 5FL Gas spring for left front wheel 5FR Gas spring for right front wheel 5RL Gas spring for left rear wheel 5RR Right rear wheel gas springs 5a, 5b, 5c, 5d gas spring unit 5e
Diaphragm 5f Gas chamber 5g of gas spring Hydraulic pressure chamber 8 of gas spring 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 15 Vertical acceleration sensor 16 Lateral Acceleration sensor 17 Control unit 18 Rudder angle sensor 19 Vehicle speed sensor 20 Drive source 21 Hydraulic pump 22 for power steering system
Accumulator 23F Front wheel side piping 23R Rear wheel side piping 23FL Left front wheel side piping 23FR Right front wheel side piping 23RL Left rear wheel side piping 23RR Right rear wheel side piping 25a, 25b, 25c, 25d Orifice 26
Switching valve 28 Unload relief valve 29... Reserve tank 33 Opening/closing valve 34 Solenoid valve 35 Relief valve 36 Ignition key interlocking valve 37 Hydraulic pump relief valve 38 Return accumulator 41 Bounce component calculation section 42 Pitch component calculation section 43 Roll line segment calculation section 44 Bounce control section 45 Pitch control section 46 Roll control section 50a, 50b, 50c, 50d Differentiator 51 Pitch component calculation section 52 Roll component calculation section 53 Pitch control section 54 Roll control section 61 Bounce component calculation section 62 Pitch component calculation section 63 Roll Line segment calculation section 64 Bounce control section 65 Pitch control section 66 Roll control section 71 Warp control section 71a Front wheel hydraulic pressure ratio calculation section 71b Rear wheel hydraulic pressure ratio calculation section 90 Suspension characteristic control device 91 Mode selection means 92 Engine output detection means 93FR , 93FL, 93RR, 93RL Brake pressure detection means 94 Torque calculation means 95 Control gain change means 96 Control gain output means 100 Fluid control amount calculation device

Claims (2)

[Claims] Claim 1: For each wheel, a fluid cylinder device is provided between the sprung weight and the unsprung weight of the vehicle, and a control gain of suspension characteristics is set and controlled according to the driving condition of the vehicle. a suspension characteristic control device;
a displacement detection means for detecting displacement of the vehicle, and a fluid cylinder device configured to cancel the displacement of the vehicle with a predetermined control gain set and controlled by a suspension characteristic control device based on the detection result of the displacement detection means. In an active suspension device that controls the amount of working fluid supplied to and discharged from the vehicle, the suspension characteristic control device controls the pitching center so that the ratio of the driving torque to the ground load of each wheel is set to a predetermined value depending on the driving state of the vehicle. A suspension device for a vehicle, comprising control gain changing means for changing the setting of the control gain so that the control gain becomes equal to or less than a value M. 2. The control gain changing device according to claim 1, wherein the control gain changing device is configured to change the setting of the control gain so that the predetermined value M becomes smaller in an acceleration state. Vehicle suspension equipment.