JPH03182825A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To improve the comfortableness of a ride and travelling property at the time of travelling on a bad road by comprising a road surface irregular condition detecting means for directly detecting the irregular condition of a road, and changing the suspension characteristic in response to the detection signal thereof. CONSTITUTION:Suspension characteristic of an active suspension device is changed by controlling supply and discharge of the pressurizing liquid to liquid- operated chambers 3c inside of fluid cylinder devices 3, respectively provided between a car body 1 and front and rear wheels 2F, 2R, with proportional flow quantity control valves 9. The proportional flow quantity control valves 9 are controlled by a control unit 17 on the basis of the output signal of car height displacement sensors 14, vertical acceleration sensors 15, etc. In this case, a road surface irregularity sensor 31, including a distance measuring unit 30 for sending the laser wave 90 toward the road surface 100 and measuring a distance between the car body 1 and the road surface 100 with a delay of the reflected wave 90', thereof, is provided in the lower part of the front end of the car body 1 to change the suspension characteristic on the basis of the output thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a suspension device for a vehicle, and particularly to an active suspension device.

(Prior Art) Conventionally, as an active suspension device for a vehicle, there is one disclosed in, for example, Japanese Patent Laid-Open No. 130418/1983. In the device of this publication, a fluid cylinder device is provided between the sprung portion of the vehicle, that is, the vehicle body side member, and the unsprung portion of the vehicle, that is, the wheel side member, corresponding to each wheel side portion H. By controlling the supply and discharge of working fluid to this fluid cylinder device, the suspension characteristics of the vehicle can be changed as desired.

In general, there are three types of vehicle vibration: bounce, pitch, and roll. F.'s active suspension system is equipped with a fluid cylinder device for each wheel, and is able to handle these three types of vehicle vibration. In order to improve riding comfort and running stability, the opening degree of the flow chamber control valve of each wheel is controlled using a predetermined control gain that is set according to the driving condition of the vehicle. It controls the supply and output of working fluid to the fluid cylinder device.

By the way, in general active suspension systems, suspension characteristics are changed based on the outputs of various sensors such as a vehicle height displacement sensor, fluid pressure sensor, vehicle vertical acceleration sensor, lateral acceleration sensor, and vehicle speed sensor. In vehicles equipped with active suspension devices, it is difficult to increase the vertical stroke amount of the unsprung part due to the capacity limit of the achiemulator, which is the pressure accumulation source of the working fluid, from the viewpoint of fail-safe and control of the maximum flow rate of the working fluid. .Especially, the stroke amount is smaller on the hump side than on the rebound side.For this reason, when driving on rough roads,
``Contact between the bottom of the vehicle body and the road surface, which is called belly strike-1, may occur, or the maximum stroke amount of the fluid cylinder device may be restricted, or contact with a bound strike or bar may occur.
There was a difficult problem in finding a balance between ride comfort and drivability.

(Objective of the Invention) Therefore, the present invention provides a fluid cylinder device that is provided between a vehicle body side member and a wheel side member corresponding to each wheel side member, and controls the supply and discharge of fluid to and from these fluid cylinder devices. The object of the present invention is to provide a suspension system for a vehicle that achieves both ride comfort and drivability when driving on rough roads in an active suspension system that can change suspension characteristics.

(Structure of the Invention) An active suspension device according to the present invention is provided with a road surface unevenness detecting means capable of directly detecting the unevenness of the road surface, and is configured to change the above-mentioned suspension characteristics according to an output signal from the detecting means. It is characterized by being

(Effects of the Invention) According to the present invention, while driving on a rough road, by detecting a convex part or four parts on the road surface before they reach the wheels, and changing the vehicle height according to the convex part or four parts, Alternatively, by changing the control gain, it is possible to prepare for the arrival of the above-mentioned convex part or four parts, so it is possible to prevent the above-mentioned belly strike or contact with the rebound flange, thereby using an accumulator with a significantly high accumulated pressure value. It is possible to achieve both the running performance and stability of the vehicle when driving on rough roads without any problems.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic side view of a vehicle equipped with a suspension device according to an embodiment of the present invention. Although only the left side of the vehicle body 1 is shown in FIG. 1, the right side of the vehicle body 1 is similarly constructed.

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. A hydraulic chamber 3C is formed in each fluid cylinder unit W3 by a piston 3b fitted into the cylinder body 3a. Each fluid cylinder device 3
The upper end of the piston rod 3d connected to the piston 3b is connected to the vehicle body l, and each cylinder body 3a is
It is connected to the front left wheel 2FL or the rear right wheel 2RL.

The hydraulic chamber 3C of each fluid cylinder device 3 communicates with the gas spring 5 through the connecting path 4, and each gas spring 5 is divided into a gas chamber 5f and a hydraulic chamber 5g by a diaphragm 5e, The chamber 5g has a communication path 4 and a fluid cylinder device 3.
It communicates with the hydraulic pressure chamber 3C of the fluid cylinder device 3 through the piston 3d.

A fluid passage 10 connecting the hydraulic pump 8 and the hydraulic chamber 3c of each fluid cylinder device 3 so as to be able to supply fluid has a flow rate of the fluid supplied to the fluid cylinder device 3 and a flow rate from the fluid cylinder device 3. A proportional flow control valve 9 is provided for controlling the flow rate of the discharged fluid.

The hydraulic pump 8 includes a discharge pressure gauge 1 that detects the discharge pressure of fluid.
2 is provided, and a hydraulic chamber 3 of each fluid cylinder device 3 is provided.
A hydraulic pressure sensor 13 is provided to detect the hydraulic pressure inside C.

Further, a vehicle height displacement sensor (stroke sensor) 14 is provided that detects the displacement of the vehicle body in the vertical direction with respect to each wheel 2FL, 2RL based on the detection of the cylinder stroke amount of each fluid cylinder device 3. The vertical acceleration sensor 15 detects the acceleration in the vertical direction, that is, the acceleration in the vertical direction on the springs of the wheels 2FL, 2RL.
One each above H and left and right rear wheels 2RL, 2R
A total of three sensors are provided, one in the center of the R in the vehicle width direction, and a steering angle sensor 18 and a vehicle speed sensor 19 are also provided.

Furthermore, a laser wave 90 is applied to the road surface 10 at the lower part of the front end of the vehicle body 1.
A distance measuring device 30 that measures the distance between the vehicle body I and the road surface 100 based on the delay of a laser reflected wave 90' emitted toward the road surface 100 and reflected by the road surface 100; A road surface unevenness sensor 31 is provided to detect the uneven state of the road surface 100 based on distance.

The discharge pressure gauge 12, the hydraulic pressure sensor 13, and the vehicle height displacement sensor 1
4. Vertical acceleration sensor 15, steering angle sensor, vehicle speed sensor 1
9 and the detection signals of the road surface unevenness sensor 31 are internally connected to the CP
The control unit 17 is configured to control the proportional control valve 9 based on these detection signals to variably control the suspension characteristics as desired.

FIG. 2 shows four fluid cylinder devices 3 from a hydraulic pump 8.
FIG. 2 is a circuit diagram of a hydraulic circuit for supplying fluid to or discharging fluid from the vehicle.

In FIG. 2, the hydraulic pump 8 is a hydraulic pump 21 for a power steering device driven by a drive source 20.
An accumulator 22 is connected to a discharge pipe 8a that is connected in parallel with the hydraulic pump 8 and discharges fluid from the hydraulic pump 8 to the four fluid cylinder devices 3. , front wheel side piping 2
It branches into 3F and rear wheel side piping 23R. 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 in communication with the hydraulic pressure chambers 3C of the fluid cylinder device 3FL for the left front wheel and the fluid cylinder device 3FR for the right front wheel, respectively. Similarly, the rear wheel side pipe 23R is the same as the front wheel side pipe 23R.
3L, it branches into left rear wheel side piping 23RL and right rear wheel side piping 23RR, and left rear wheel side piping 23RL
And the right rear wheel side pipe 23RR communicates with the hydraulic chamber 3c of the fluid cylinder device 3RL for the left rear wheel and the fluid cylinder device 3RR for the right rear wheel, respectively.

These four fluid cylinder devices 3F L, 3FR13
Gas springs 5FL and 5FR1 are installed in RL and 3RR, respectively.
5RL and 5RR are connected, and each gas spring 5FL,
5FR15RL, 5RR are four gas spring units 5
a, 5b, 5c, and 5d, and these gas spring units 5a to 5d are connected to a branch communication path 4 that communicates with the hydraulic pressure chamber 3 (of the corresponding fluid cylinder device 3FL, 3FR10 3 Rt, and 3RR, respectively). They are connected through passages 4a, 4b, 4c, and 4d, respectively.In addition, each gas spring 5F1.
,． 5FR15R1,...,5RR branch communication path 4a~
4d have orifices 25a, 25b, 25, respectively.
L-1Q5d are provided 1 and these orifices 2
5a to 25d (7) i%l for 1 and gas spring 5F
L7.5 F R15R] 1.5RR (7) Gas chamber 5r
The high-frequency vibrations applied to the vehicle are reduced by the buffering effect of the gas sealed in the vehicle.

Among the gas spring units 5a to 5d constituting each gas spring 5F11.5FR, 5R1, 5RR, the hydraulic chamber 3 of each fluid cylinder device 3FL, 3FR13RL, 3RR
cL, :, the nearest (first installed at 1Σ1d)
The communication path 4 between the gas spring unit 5a and the second gas spring unit 5b adjacent thereto is provided with gas springs 5FL, 5FR15RL by adjusting the passage area of the communication path 4.
, 5RR is provided with a switching valve 26 for switching the damping force. This switching valve 26 has two positions: an open position (the illustrated position) in which the communication passage 4 is opened, and a throttle position in which the area of the communication passage 4 is narrowed.

An unlow 1-relief valve 28 is connected to the discharge pipe 8a of the hydraulic pump 8 near the connection part of the accumulator 22 on the flow side. When the value of -L is greater than the tenth limit, the hydraulic pump 8 is switched to the open position, and the fluid discharged from the hydraulic pump 8 is directly returned to the reservoir tank 29 to maintain the accumulated hydraulic pressure of the accumulator 22 at a predetermined value. controlled by. In this way, each fluid cylinder device 3F+7.3FR, 3R
The liquid is supplied to L and 3RR by an accumulator 22 which is maintained at a predetermined pressure accumulation value. Note that FIG. 2 shows a state in which the unload relief valve 28 is located in the closed position.

As is clear from Fig. 2, the hydraulic pressure circuits for the left front wheel, right front wheel, left rear wheel, and right rear wheel are constructed in the same way. The explanation of is omitted.

Proportional flow ff1tli provided in left front wheel side piping 23FL
The lJ control valve 9 is a three-way valve, and has two positions: a closed position where the entire boat is closed, as shown in FIG. Fluid cylinder device 3 F of front wheel side piping 23FL 1. , and a discharge position that communicates with the return passage 32. Further, the proportional flow rate control valve 9 includes pressure compensation valves 9a, 9a.
, 9a, when the proportional flow control valve 9 is in the supply or discharge position, the fluid cylinder device 3F1. The hydraulic pressure in the hydraulic pressure chamber 3c is maintained at a predetermined value.

A pilot pressure-responsive ntl closing valve 33 that can open and close the left front wheel side piping 23 FL is installed on the fluid cylinder bag opening 3FK side of the proportional flow rate control valve 9. This opening/closing valve 33 is configured such that when the solenoid valve 34 that guides the hydraulic pressure of the left front wheel side piping 23PL of the hydraulic pump 8 example of the proportional flow rate control valve 9 is opened, the hydraulic pressure of the solenoid j↑34 is changed to is introduced, and when this pilot pressure is equal to or higher than a predetermined value, the proportional flow 11
tilJ control: Fluid cylinder device 3F1 by #9. This allows the flow rate of fluid to be controlled.

Further, when the fluid 1jE in the fluid pressure chamber 3c of the fluid cylinder device 3FL rises abnormally, it opens and the fluid pressure chamber 3c opens.
Relief-tf35 that returns the fluid inside to the return passage 32
and the discharge pipe 8 near the downstream side of the connection part of the accumulator 22.
an ignition key chain valve 36 that opens when the ignition is turned off to return the liquid stored in the accumulator 22 to the reservoir tank 29 and release the high pressure state in the accumulator 22, and the liquid discharge of the hydraulic pump 8. A hydraulic pump relief valve 37 that returns the liquid in the hydraulic pump 8 to the reservoir tank 29 to lower the liquid discharge pressure of the hydraulic pump 8 when the pressure increases abnormally, and a return passage 32.
connected to the fluid cylinder device 3 F 1. A return accumulator 3 that performs a pressure accumulating action when discharging fluid from the
8 are provided respectively.

Next, FIGS. 3A and 3B show the suspension characteristic control in the 22 to 17 unit (O')
It is a block diagram.

3A and 3B, the suspension characteristic control device provided in the control unit 17 according to the present embodiment outputs vehicle height displacement signals X, X, . . . , X R11%
Control system A that controls the vehicle height to the target vehicle height based on X RL, and vehicle height displacement signals XFR% XFl, % XllR
% Vehicle height displacement speed signal V F obtained by differentiating XRL
Based on R+ Y F I, YR, l, YRL,
A control system B that suppresses the vehicle height displacement speed, a control system C that aims to reduce the vertical vibration of the vehicle based on the vertical acceleration signals G, , G, , G9 of the three vertical acceleration sensors 15, and Pressure signal PFR-FFL-P□ of the wheel hydraulic pressure sensor 13
, PRl, and a control system that calculates and controls the torsion of the vehicle body.

The control system A includes a bounce component calculation section 40, a pitch component calculation section 41, and a roll component calculation section 42. The bounce component calculation unit 40 adds the outputs XF and XFR of the vehicle height sensors 14 of the left and right front wheels 2FL and 2FR, and adds the outputs XRL, X, and This is a section that calculates the bounce component of the vehicle by adding up the bounce component of the vehicle, and the pinch component calculation section 41 calculates the bounce component of the left and right rear wheels from the added value of the output 5 2RL, 2
This section calculates the pitch component of the vehicle by subtracting the added value of the output Xt+L of the vehicle height sensor 14 of the RR, XRR. Further, the roll component calculation unit 42 calculates the output XFL% of the vehicle height sensor 14 of the left and right front wheels 2FL and 2FR.
R difference X□-XFL and left and right rear wheels 2RL, 2RR (
7) Vehicle height control 4t140) Output

Further, the control system A includes a bounce control section 43, a pitch control section 44, and a roll control section 45. The bounce component of the vehicle and the target average vehicle height TII calculated by the bounce component calculation part 40 are input to the bounce control part 43, and based on the gain coefficient of 1, the bounce component of the vehicle calculated by the bounce component calculation part 40 is inputted, and based on the gain coefficient of 1, the bounce component and target average vehicle height TII are input to the bounce control part 43. Calculate the control amount. The pitch component of the vehicle calculated by the pitch component calculation part 41 is input to the pitch control part 44, and the control amount of each flow rate control valve 9 in pinch control is calculated based on the gain coefficient and □. The roll component and target roll displacement amount TR calculated by the roll component calculation unit 42 are input to the roll control unit 45, and a gain coefficient KI is input to the roll control unit 45.
Based on IFI and K□1, the control amount of each flow control valve 9 in roll control is calculated so that the vehicle height corresponds to the target roll displacement amount TR.

In order to control the vehicle height to the target vehicle height, each of the control units 4
The control amount calculated in 3.44.45 has its sign reversed for each wheel, that is, the vehicle height displacement signal XF, X, I*, X detected by the vehicle height sensor 14.ゎ is reversed so that its sign is opposite, and then the bounce, pitch, and roll control amounts for each wheel are added, and the command flow rate signal for the proportional flow control valve 9 of each wheel in the control system A is calculated. High displacement components QF□, QFLI, QRR
1% Q-1LL+ is obtained.

Note that a dead band device 70 is provided between each vehicle height sensor 14 and the bounce calculation section 40, pinch calculation section 41, and roll calculation section 42, and a vehicle height displacement signal X1R+ from the vehicle height sensor 14 is provided. XFL, 7 These vehicle height displacement signals XFR,
RR and XR1 are output to each calculation section 40, 41, and 42.

Next, the control system B includes four differentiators 46, and these differentiators 46 differentiate the vehicle height displacement signal XFRNXFL%XRR%XRt from the vehicle height sensor 14, respectively. , vehicle height displacement speed signal Y□, Y, , Y, ,
Calculate YRL.

Note that the vehicle height displacement speed signal Y is obtained from the following equation.

Y = (Xn −Xn−+)/T where Xn: Vehicle height displacement amount at time t Xn−I:
Vehicle height displacement amount T at time t-1; Sampling time The control system B includes a pitch component calculation section 47a and a roll component calculation section 47b. The pitch component calculation unit 47a calculates a vehicle height displacement speed signal YF for the left and right front wheels 2PL and ZFR.
The pitch component of the vehicle is calculated by subtracting the added value of the vehicle height displacement speed signal Y on the left and right rear wheels 2RL and XRR side, Y+u+, from the added value of L and Y□. The roll component calculation unit 47b calculates the left and right front wheels 2F.
L, 2FR side vehicle height displacement speed signal Y F 1. +
VFR difference Y, R-Y rt and left and right rear wheels 2
R12, 2RR side vehicle height displacement speed signal YRL, YRR
The difference Y and 1RY1 are added to calculate the power of one coil of the vehicle.

The pitch component of the vehicle calculated by the pitch component calculation section 47a as described above is manually input to the pitch control section 48, and the control amount of each flow rate control valve 9 in pitch control is calculated based on the gain coefficients K and d. Ru.

[1-R
Based on F2 and KRR2, the /Jt amount control amount to each flow rate control section 9 in roll control is calculated by /rJ.

Further, each control amount calculated by the pitch control section 48 and the roll control section 49 has its sign reversed for each wheel.
That is, the vehicle height displacement speed signal Y calculated by the differentiator 46
F R-, Y F L,, Y RR+ Y *
+ is the TF, * is the opposite (-), and then the pitch and roll control amounts for each wheel are added, and the proportional flow control valve for each wheel is added to the control system B. Vehicle height displacement speed component Q of the command flow rate signal for 9
,R,,Q, ,,,QRR2,Q,,,2 are obtained.

The control system C includes a bounce component calculation section 50, a pitch component calculation section 51, a roll component calculation section 52, and a bounce control section 5.
3, a pitch control section 54, and a roll control section 55.

The bounce component calculation unit 50 is a section that calculates the bounce component of the vehicle by adding the outputs cr*-GFI and G8 of the three single-cutter lower blade lI speed sensors 15, and the bounce component calculated here is the bounce component of the vehicle. It is manually operated by the control section 53. The bounce control unit 53 calculates the control amount of each proportional flow rate control valve 9 in bounce control based on the gain coefficient KB3.

The pitch component calculation unit 51 calculates the left and right front wheels 2 FL, 2F.
Vertical acceleration sensor 15 installed on the L side of R
Sum of 1/2 of the output of (G FR + G rt,) / 2
From this, an L is installed at the center of the left and right rear wheels in the vehicle width direction.
This section calculates the pitch component of vehicle 0 by calculating the output Gn of the lower JJI+speed sensor 15 by M, and the pitch component calculated here is manually input to the pitch control section 54.

The pitch control unit 54 calculates the control amount of each proportional flow rate control valve 9 that is involved in pitch control based on the gain coefficient Kr3.

The roll component calculation unit 52 calculates the roll component of the vehicle by subtracting the output G F L of the -L lower blade 11 speed sensor I5 on the left front wheel side from the output GFR of the vertical acceleration sensor ``+15'' on the right i13 wheel side. The roll component calculated here is manually input to the roll control section 55.In the roll control section 55, the gain-in coefficient KRFI,K,l,+3
Based on the following, each proportional flow control valve 9 for roll control
Calculate the control amount.

In order to suppress the vertical vibration of the vehicle with a bounce component, a pitch component, and an I-]-le component,
．． The positive and negative values of each control amount calculated in 54 and 55 are reversed for each wheel, and then the bounce, pitch, and roll control amounts for each wheel are added, and in the control system C, the proportional flow control valve 9 −L downward acceleration component Q F R3, Q, , , QRR,, QR, of the command flow rate signal for the command flow rate signal is obtained.

In addition, three "two-lower acceleration sensors 15 and each calculation section 50.
51 and 52, a dead band device 80 is provided between the vertical acceleration sensor 15 and the vertical acceleration signal GFR-Gvt-Gu that exceeds a preset dead band Xc-tl-. These lower acceleration signals GFR, GFT, and GM are output to the respective control units 50, 51, and 52 only at certain times.

Next, the control system includes a warp control section 60 consisting of a front wheel hydraulic pressure ratio calculation section 60a and a rear wheel hydraulic pressure ratio calculation section 60b.

The front wheel side hydraulic pressure ratio calculation unit 60a calculates the ratio of the hydraulic pressure difference (PFRPFL) to the sum of these hydraulic pressures (PFR+PF1.) based on the input hydraulic pressure signals Pr*+PyL of the two front wheel side hydraulic pressure sensors 13. Pt=(PvRPFL)/(P
r*+PFI,), and if this hydraulic pressure ratio P is −ω, < p, < ω1 with respect to the threshold hydraulic pressure ratio ω, the calculated hydraulic pressure ratio P is used as is. Output, P, <
-ω1 or P,>ω, the threshold hydraulic pressure ratio -ω or ω is output. Similarly, the rear wheel side hydraulic pressure ratio calculating section 60b calculates the input hydraulic pressure signals P□, P of the two rear wheel side hydraulic pressure sensors 13.
Based on IL, the sum of these liquid pressures (pHl+PRL)
Ratio of hydraulic pressure difference (P ** P RL) to P r
Calculate = (PRR-PRL)/(PRR+PIIL). Then, in the Umep control unit 60, after multiplying the rear wheel side hydraulic pressure ratio Pr by a predetermined value by a gain coefficient ω, subtracting this from the front wheel side hydraulic pressure ratio Pr, and multiplying the result by a predetermined value by a gain coefficient ω, On the front wheel side, the pressure component of the command flow signal for each proportional flow control valve 9 is QFR4
, QFL4, QRl14, Q, L, are obtained.

The vehicle height displacement components Q□QFl, Q**+tl, Q8° of the command flow rate signal determined for each proportional flow control valve 9 in each control system A-, D obtained as described above, and the vehicle height Displacement velocity component Q, , QFL2, QllI12, Q,1
．． .

and vertical acceleration component Q□3, QFL8, Q, R,, QR
l3 and pressure component Q,...,Qrta,QR,14,Q
*1. J and 3 are finally added to give a total flow signal QFR+QF''
A good QRR and QRl can be obtained.

Table 1 shows an example of a map of coefficients representing control gains used in each of the control systems A to D, which is stored in the control unit 17, and seven modes are set depending on the operating state. has been done.

(11 Mode 1: State for 60 seconds after the engine stops.

(2) Mode 2: The ignition switch is turned on, but the vehicle is stopped and the vehicle speed is zero.

(3) Mode 3: A straight-ahead state where the vehicle's lateral acceleration Gs is 0.1 or less.

(4) Mode 4: A slow turning state in which the lateral acceleration Gs of the vehicle exceeds 0.1 and is below 0.3.

(5) Mode 5: Medium turning state in which the lateral acceleration Gs of the vehicle exceeds 0.3 and is below 0.5.

(6) Mode 6: A sharp turning state in which the vehicle's lateral acceleration Gs exceeds 0.5.

4 (7) Mode 7: When the reverse roll mode is selected by the roll mode selection switch (not shown) and the vehicle is in a slow turning state where the lateral acceleration Gs exceeds 0.1 and is equal to or less than 0.3, mode 4 is selected. This mode is selected in place of the mode 4, and when the vehicle speed exceeds 120 km/h, the mode is automatically switched to mode 4 even if the reverse roll mode is selected.

In Table 1, Q14A+t indicates the maximum flow rate control amount of the fluid supplied to the proportional flow control valve 9 of each wheel, and P
MAI indicates the maximum pressure within the hydraulic pressure chamber 3C of the fluid cylinder device 3, and is set so that fluid does not flow back into the accumulator 22 from the hydraulic pressure chamber 3C. PMI
N indicates the minimum pressure in the hydraulic chamber 3C of the fluid cylinder device 3, and if the pressure in the hydraulic chamber 3C decreases excessively, the gas spring 5
It is set so that it will not be damaged due to overstretching. Note that the arrows in Table 1 indicate that the control gain coefficients are set to the same value as the numerical value indicated by the arrow.

In Table 1, except for mode 7, each control gain coefficient is set such that the larger the mode number, the more the suspension control is performed with emphasis on driving stability.

6 Next, in the vehicle suspension system according to the embodiment of the present invention, when driving on a rough road, the target average vehicle height Tl1( +n), the vehicle height displacement speed gain coefficient KP27L/min/(Nl/5ec) of the pitch control unit 48 in the control system Bt, and the pitch control unit 54 in the control system C shown in FIG. 3B. For the acceleration gain coefficient, S/torr/min/G, the vertical acceleration gain coefficient KRF3, KRR, liter 7 min/G of the roll control section 55 in control system C, and the maximum flow control MQ, lAX liter 7 min. is changed from the map value shown in Table 1 based on the detection of the uneven state of the road surface 100 by the road surface unevenness sensor 31, and control for countermeasures against rough roads is performed. explain.

In FIG. 4, first, in step S1, the road surface unevenness sensor 3
The road surface condition is recognized and confirmed by the output signal of step S.
If it is detected in step 2 that the road is uneven, the process proceeds to step S3, and by setting the target average vehicle height T8 to +10 mm (Tl1-0 in the map), the height of the vehicle 8 is raised by 10 mm compared to the normal state. to prevent stomach punches. Next, proceeding to step 54-1, the acceleration gain coefficient +<+ of the bi-control unit 54 in the control system C, where a is set as the travel mode, is the maximum ma-bu value K I:+=
] 5 liters/min/'G, further increasing it to +20 liters/min/G, and
[Lower acceleration gain coefficient KRF3, K of the roll control unit 55
Map values KR, 3, K for RR2 to travel mode 5
ll+13-30 liters/min/G
The vertical acceleration control gain of the control unit 55 is increased, thereby making it difficult for the vehicle body attitude to change.

If the concave Inl path continues to curve for a predetermined period of time, the maximum flow Mt value Q is determined in step S5. - is Ma, Bu (iQ's 1
The active control sensitivity is decreased from 8 liters/minute to 13 liters/minute to prevent the accumulated pressure value of the accumulator 22 from decreasing.

Next, if it is detected that there is a problem on the uneven road in step S2, the process proceeds to step S6, and if it is detected that the circuit is a circuit, then in step S7 By setting the target average vehicle height 1゛1.9 to -10 mm, the vehicle height is lowered by 1 (in) than the normal state, and the stroke in the extension direction of the fluid cylinder device 3 has a margin, and the following In step s8, the vertical acceleration gain coefficient Kr3 of the pitch control unit 54 in the control system C is set to the maximum map value KP3=]5 liters/
Equal to min/G.

Further, if it is detected in step S6 that it is not a circuit, the process advances to step s9, and if the road is a bumpy road, the process advances to Step 7 SIO, and as in the case of a bumpy road,
The target average vehicle height T is set to +10 mm, and in the next step Sll, the pitch control unit 4 in the control system B
By changing the vehicle height displacement speed gain coefficient K P2 of 8 to 0.05 liter/min/(w/5ec), in the map, □-
〇), increase the vehicle height displacement speed gain, and step S
At step 12, the vertical acceleration gain coefficient KP1 of the pitch control section 54 in the control system C is made equal to the maximum map value KP1=15 liters/minute/G in the driving mode.

In this way, when the vehicle is traveling on a rough road, the vehicle height is changed and the required control gain is changed, making it possible to achieve both ride comfort and smooth running.

Note that if it is not detected in step S9 that the road is a convex road, the road surface is considered to be a flat road, and the above-mentioned rough road countermeasure control is not performed, and the value of each coefficient is set to the first level in step S313.
Restore the map values shown in the table.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram showing a suspension device for a vehicle according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a hydraulic circuit for controlling supply and discharge of fluid to the fluid cylinder device, FIG. 3A, FIG. 3B is a block diagram of the suspension characteristic control device in the control unit, and FIG. 4 is a flowchart of rough road countermeasure control. 1 - Vehicle body 2F, 2R - Front wheels, rear wheels 3 - Fluid cylinder device 3C hydraulic pressure chamber 3d - Piston rod 5 = Gas spring 8 - Hydraulic pump 9 - Proportional flow control valve 13 Hydraulic pressure sensor
14-Vehicle height displacement sensor 1 Vertical acceleration sensor control unit accumulator 30-Distance measuring device Road surface unevenness sensor Bounce component calculation section Pitch component calculation section Roll component calculation section Bounce control section 44-Pinch control section Roll control section 46-Differentiator pitch component Calculation unit Roll component calculation unit Pitch control unit 49 Bounce component calculation unit Pitch component calculation unit Roll component calculation unit Bounce control unit 54- Pitch control unit Roll control unit
60 - Warb control section Front wheel side hydraulic pressure ratio calculation section Rear wheel side hydraulic pressure ratio calculation section〇 - Dead band device roll control section

Claims (1)

[Claims] 1. A fluid cylinder device is provided between a vehicle body side member and a wheel side member corresponding to each wheel side member, and fluid supply and discharge to these fluid cylinder devices is controlled. According to the present invention, an active suspension device capable of changing suspension characteristics is provided with a road surface uneven state detection means capable of directly detecting an uneven state of the road surface, and configured to change the suspension characteristics according to an output signal from the detection means. A vehicle suspension device characterized by: 2. The vehicle according to claim 1, further comprising vehicle height changing means for changing the supply and discharge of fluid to each fluid cylinder device so as to change the vehicle height in accordance with the change in suspension characteristics based on the detection of the uneven state of the road surface. equipment. 3. Vertical acceleration detection means for detecting the acceleration in the vertical direction of the vehicle body side member of the vehicle, and vertical acceleration control for controlling the supply and discharge of fluid to and from the fluid cylinder device based on the acceleration signal from the vertical acceleration detection means. means and
3. The apparatus according to claim 1, further comprising means for increasing a control gain of the vertical acceleration control means when an uneven road is detected by the road surface unevenness detection means. 4. Claim 3, further comprising means for reducing the maximum flow rate control amount of the fluid supplied to the fluid cylinder device when the uneven road condition detecting means detects that the uneven road continues for a predetermined period of time or more. The device described. 5. Means for obtaining a vehicle height displacement speed signal representing the vertical displacement speed of the vehicle body with respect to each wheel, and vehicle height displacement speed control for controlling the supply and discharge of fluid to the fluid cylinder device based on the vehicle height displacement speed signal. 3. The apparatus according to claim 1, further comprising means for increasing a control gain of said vehicle height displacement speed control means when a bumpy road is detected by said road surface unevenness detection means.