JP3123579B2 - Body attitude control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an attitude control apparatus for a vehicle body, and more particularly, to an operation of a hydraulic suspension mechanism so that a piston of the hydraulic suspension mechanism does not collide with a cylinder end wall against an excessive input from a road surface to an axle. The present invention relates to an attitude control device for a vehicle body, which electrically limits the amount of the vehicle and improves the riding comfort.

[0002]

2. Description of the Related Art In a vehicle attitude control apparatus disclosed in Japanese Patent Application Laid-Open No. Sho 64-30816, the relative vertical displacement of each axle and a vehicle body is controlled in order to suppress a change in the vehicle body attitude caused by input from a road surface or the like. The amount of oil in the hydraulic suspension mechanism (to be precise, the hydraulic suspension mechanism in the following, the same applies hereinafter) is adjusted according to the amount, but if an excessive thrust force acts from the road surface to the axle, the hydraulic suspension mechanism The mechanism is shortened excessively. At this time, the piston of the hydraulic suspension mechanism may strike the cylinder end wall and be damaged. If a mechanical stop is provided at the operating limit of the hydraulic suspension mechanism, breakage of the hydraulic suspension mechanism can be prevented.However, when the operating part of the hydraulic suspension mechanism hits the stopper, a large impact is generated and noise is generated. Or make the ride uncomfortable.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to take into account each motion mode of a vehicle body from a relative vehicle height change amount between each wheel and the vehicle body detected by a vehicle height sensor. In relation to the obtained maximum value of the displacement amount (modal displacement amount) of each wheel supporting portion of the vehicle body, by substantially limiting the attitude control amount for electrically feedback controlling the oil amount for the hydraulic suspension mechanism, An object of the present invention is to provide a vehicle body attitude control device that prevents a piston of a hydraulic suspension mechanism from colliding with a cylinder end wall.

[0004]

In order to attain the above object, according to the present invention, a roll displacement, a pitch displacement and a vertical displacement of a vehicle body based on a signal from a vehicle height sensor for detecting the vehicle height of each wheel. And a control amount for obtaining a roll control torque F12, a pitch control torque F22, and a vertical displacement control force F32 of each wheel for keeping the vehicle body flat based on a signal from the relative displacement amount calculation means. Calculating means;
An oil amount calculating means for obtaining an oil amount of the hydraulic suspension mechanism of each wheel based on a signal of the control amount calculating means; an oil amount control valve for adjusting the oil amount of each hydraulic suspension mechanism based on a signal of the oil amount calculating means; F12 = k1, .DELTA..phi. + K2..DELTA..phi. '+ K7..DELTA..phi.dt, F22 = k3..DELTA..theta. + K4..DELTA..theta. + K8..DELTA..DELTA.dt F32 = k5..DELTA.x + k6..DELTA.x' + k9..DELTA..DELTA. : Negative feedback gain coefficient k7 to k9: Constant Δφ: Body roll displacement Δθ: Body pitch displacement Δx: Body vertical displacement From the vehicle height detected by the vehicle height sensor provided in each hydraulic suspension mechanism, The vertical displacements xB, xR, xP, and xW of the wheel support portions of the vehicle body corresponding to the bouncing, roll, pitch, and warp motion modes are obtained, and xB = BF (hFL + hFR) + BR (hRL + hRR) xR = RF ( hFL-hFR) + RR (hRL-hR R) xP = PF (hFL + hFR)-PR (hRL + hRR) xW = WF (hFL-hFR)-WR (hRL-hRR) where xB: bounce displacement xR: roll displacement xP: pitch displacement xW: warp displacement hFL: Detected vehicle height of left front wheel hFR: Detected vehicle height of right front wheel hRL: Detected vehicle height of left rear wheel hRR: Detected vehicle height of right rear wheel BF, BR: Bounce displacement force coefficients of front and rear wheels RF, RR: Front and rear Roll displacement force coefficients of wheels PF, PR: pitch displacement force coefficients of front and rear wheels WF, WR: warp displacement force coefficients of front and rear wheels The displacement amount xw for each motion mode of each wheel supporting portion of the vehicle body is expressed by the following equation: xwFL = xB + xR + xP + xW = XB-xR + xP-xW xwRL = xB + xR-xP-xW xwRR = xB-xR-xP + xW, and the negative feedback gain coefficients k1 to k6 are given by the following equations: k = kin + kbs (xwmx / xbm) ⁿ where kin is the initial value kbs Is a constant xwmx: for each motion mode of each wheel support The maximum value xbm of the displacements is determined by the operating limit of the hydraulic suspension mechanism.

[0005]

According to the present invention, an excessively large vehicle is obtained by continuously adjusting the negative feedback gain coefficient (feedback gain) of the attitude control according to the vertical displacement (vehicle height change) of each wheel supporting portion of the vehicle body. Avoid the mechanical collision of the working part of the hydraulic suspension mechanism against high change, and improve the riding comfort.

The relative displacement and the relative displacement speed are based on the ratio (bump stop ratio) between the maximum value of the displacement exerted on each wheel support by each motion mode of the vehicle body and the operation limit (maximum bump amount) of the hydraulic suspension mechanism. And the negative feedback gain coefficient to be multiplied by is limited, and the oil amount for the hydraulic suspension mechanism is limited to a predetermined value or less. As a result, even if an excessive road input acts on the wheels,
Inhibiting the hydraulic suspension mechanism from reaching operating limits.

[0007]

FIG. 1 is a hydraulic circuit diagram of a hydraulic suspension mechanism according to the present invention. The hydraulic pump 4 driven by the engine sucks oil from the oil tank 2 and supplies the oil from the pipe 5 to the accumulator 8 of the pipe 7 through the check valve 6. Oil pressure monitoring means A is provided to keep the oil pressure to the pipe 7 at a predetermined value. That is, when the detection value of the oil pressure sensor 9 for detecting the oil pressure of the pipe 5 exceeds a predetermined value,
The switching valve 12 is switched, and a part of the pressure oil in the pipe 5 is
The oil is returned to the oil tank 2 via the switching valve 12, the pipe 13, and the filter 27. Also, when the oil pressure at the discharge port of the hydraulic pump 4 becomes abnormally high, a part of the pressure oil in the pipe 5 is changed to the known relief valve 26 and the pipe 1.
3. It is returned to the oil tank 2 via the filter 27.

[0008] The pressure oil in the pipe 7 is divided into left and right front wheels and left and right rear wheels 25.
(Only the left front wheel is shown as a representative in FIG. 2). The hydraulic suspension mechanism 19 fits a piston 22 in a cylinder 23 and connects a rod 24 projecting upward from the piston 22 to the vehicle body 20, and a wheel 25 projecting downward from the cylinder 23 to a wheel 25.
It is connected to the knuckle. A spring 21 is interposed between the wall of the cylinder 23 and the vehicle body 20. A vehicle height sensor 28 for detecting a relative vertical displacement between the vehicle body 20 and the wheel 25 is provided between the vehicle body 20 and the nuticle. When specifying the suspension mechanisms 19 for the left and right front wheels and the left and right rear wheels,
The subscripts of FL, FR, RL, and RR will be added.

The pressure oil in the pipe 7 is supplied to a check valve 14, an oil amount control valve 1 comprising a general neutral position closed type electromagnetic proportional pressure control valve.
6. The pressure is supplied to the pressure accumulator 18 via the throttle 18a, and further supplied to the lower end chamber of the cylinder 23 of the hydraulic suspension mechanism 19. The oil pressure supplied to the lower end chamber of the cylinder 23 is detected by the oil pressure sensor 17. When the oil amount control valve 16 is switched, the oil in the lower end chamber of the cylinder 23 is returned to the oil tank 2 via the oil amount control valve 16, the check valve 15, the pipe 13, and the filter 27.

Each of the hydraulic suspension mechanisms 19 for supporting the front, rear, left and right wheels is independently provided with check valves 14, 15, an oil amount control valve 16,
An aperture 18a, an accumulator 18, a hydraulic pressure sensor 17, and a vehicle height sensor 28 are provided. In order to detect the lateral acceleration and the longitudinal acceleration of the vehicle, a lateral acceleration sensor 31 and a longitudinal acceleration sensor 32 are provided at the position of the center of gravity of the vehicle (see FIG. 3).

Assuming that hFL, hFR, hRL, and hRR are relative vehicle heights of each wheel support of the vehicle body 20 with respect to the axle, the vertical displacement x of each wheel support of the vehicle body is expressed by the following equation (1). Is done.

XFL = hFL-hoFL xFR = hFR-hoFR xRL = hRL-hoRL xRR = hRR-hoRR (1) where hoFL, hoFR, hoRL, hoRR: the standard vehicle height 20 of each wheel support of the vehicle. The relative roll displacement (angle) Δφ, the relative pitch displacement (angle) Δθ, and the relative vertical displacement Δx of the vehicle and the axle are expressed by the following equation (2).

Δφ = k11 (xFL−xFR) + k12 (xRL−xRR) Δθ = k21 (xFL + xFR) −k22 (xRL + xRR) Δx = k31 (xFL + xFR) + k32 (xRL + xRR) (2) where k11, k21, k31 : Constants determined by vehicle specifications k12, k22, k32: Constants determined by vehicle specifications Roll displacement φ2, pitch displacement θ2, and vertical displacement x2 of the vehicle body with respect to the road surface are expressed by the following equation (3). You.

Φ2 = φ1 + Δφ θ2 = θ1 + Δθ x2 = x1 + Δx (3) where φ1: the roll displacement between the road surface and the axle θ1: the pitch displacement amount between the road surface and the axle x1: the vertical displacement between the road surface and the axle Displacement Δφ: Roll displacement between axle and vehicle body Δθ: Pitch displacement between axle and vehicle body Δx: Vertical displacement between axle and vehicle body The displacement of vehicle body 20 in response to road surface input during straight running of the vehicle Each motion of roll, pitch, and vertical displacement can be represented by the following equation of motion (4).

IX (d ² φ / dt ² ) = − k 1 Δφ−k ² Δφ ′ + F 12 I Y (d ² θ / dt ² ) = − k 3 ΔΔ−k 4 ΔΔ ′ + F 22 m ² (d ² x / dt ² ) =-k5..DELTA.x-k6..DELTA.x '+ F32 (4) where IX: inertia moment of the body relative to the roll IY: moment of inertia of the body relative to the pitch m2: mass of the body k1 to k6: negative feedback gain coefficient ( Δφ ′: Vehicle body displacement speed Δθ ′: Vehicle body pitch displacement speed Δx ′: Vehicle body vertical displacement speed F12: Vehicle body roll control force (torque) F22: Vehicle body pitch control force (torque) F32: Vertical displacement control force of the vehicle body In view of the transient characteristics of the movement of the vehicle body 20, in order to keep the vehicle body 20 flat (parallel to the road surface) with respect to the road surface input during straight running at a constant speed, each hydraulic Should be given to the vehicle body 20 by the suspension mechanism 19 Lumpur control force F12, pitch control force F2
2. The vertical control force F32 is determined as in the following equation (5).

F12 = k1 · Δφ + k2 · Δφ ′ + k7 · ∫Δφdt F22 = k3 · Δθ + k4 · Δθ '+ k8 · ∫Δθdt F32 = k5 · Δx + k6 · Δx ′ + k9 · ∫Δxdt (5) where k7 to k9: The first term on the right side of the equation (5) is the roll displacement amount Δ of the vehicle body 20.
φ, the pitch displacement Δθ, the spring drag related to the vertical displacement Δx, the second term is the viscous drag related to the roll displacement speed Δφ ′, the pitch displacement speed Δθ ′, and the vertical displacement speed Δx ′ of the vehicle body 20, the third term Is an integral term for removing the steady-state error.

The above-mentioned attitude control forces F12, F22, and F32 correspond to the roll, pitch, and vertical movements of the vehicle body 20 due to changes in the road surface. Movement (posture change) of the vehicle body 20 due to inertial force
By adding a posture control force (torque) corresponding to the above, control accuracy and responsiveness can be improved.

When the vehicle is traveling on a flat road surface having no unevenness, the following equation of motion (6) holds for each roll and pitch motion of the vehicle body 20.

IX (d ² φ / dt ² ) = m ² · g 1 · h R + m 2 · g · h R · φ 2 -ks 1 · φ 2 + F 11 I Y (d ² θ / dt ² ) = m 2 · g 2 · hP + m 2 · g · hP · θ 2- ks2 ・ θ2 + F21 (6) where g1: lateral acceleration g2: longitudinal acceleration g: acceleration of gravity hR: height difference between vehicle center of gravity and roll center hP: height difference between vehicle center of gravity and pitch center ks1: roll rigidity of spring 21 Coefficient ks2: Pitch stiffness coefficient of spring 21 F11: Roll control force during turning F21: Pitch control force during acceleration / deceleration In equation (5), the first term on the right side is lateral acceleration g1 acting on the center of gravity of the vehicle (longitudinal acceleration) g2) is a moment that causes the body 20 to roll (pitch), and the second term is a moment m2 · g · that the gravitational acceleration g acting on the vehicle center of gravity due to the roll (pitch) of the body 20 causes the body 20 to roll (pitch).
hR · sinφ2 (m2 · g · hP · sinθ2), the third term is spring 21
Is a roll restoring force (pitch restoring force) exerted on the vehicle body 20 by the reaction force of the vehicle.

Therefore, on a flat road surface without unevenness, φ2 =
Considering Δφ, θ2 = Δθ, roll control force F1 during turning
2. The pitch control force F22 during acceleration / deceleration running is calculated by the following equation (7).
Determined as follows.

F11 = −m2 · g1 · hR−m2 · g · hR · Δφ + ks1 · Δφ F21 = −m2 · g2 · hp−m2 · g · hP · Δθ + ks2 · Δθ (7) From the above results, each wheel is obtained. Control oil amount VF of hydraulic suspension mechanism
L, VFR, VRL, and VRR are represented by the following equation (8).

VFL = −kV1 · F12−kV2 · F22 + kV5 · F32−kV7 · F11−kV9 · F21 VFR = + kV1 · F12−kV2 · F22 + kV5 · F11 + kV7 · F11−kV9 · F21 VRL = −kV3 · F12 + kV6 · F12 + kV6 · F12 + kV4 · F12 + kV6 · F12 + kV4 · F12 + kV4 · F12 + kV6 · F12 + kV4 · F12 + kV4 · F12 + kV4 · F12 + kV6 −kV8 · F11 + kV0 · F21 VRR = + kV3 · F12 + kV4 · F22 + kV6 · F32 + kV8 · F11 + kV0 · F21 (8) where kV0 to kV9: Constant In the present invention, the piston of the hydraulic suspension mechanism 19 is used for an excessive road surface input. The amount of operation of the hydraulic suspension mechanism 19 is limited so that the cylinder 22 does not collide with the end wall of the cylinder 23. In particular, in a vehicle equipped with a hydraulic suspension mechanism that suspends the front wheels independently and the rear axle at both ends, there is no problem in each of the bouncing mode and the pitching motion mode, but as shown in FIG. In each motion mode of warp (movement in which the front and rear portions of the vehicle body are tilted to opposite sides (sideways)), the vehicle height sensor 2 is used.
If the wheel 8 is disposed inside the wheel (on the left and right sides of the axle), the distance between the wheel and the vehicle body is not proportional to the vehicle height detected by the vehicle height sensor 28. In each of the roll and warp motion modes, even when the vehicle height detected by the vehicle height sensor 28 does not reach the operation limit of the hydraulic suspension mechanism 19, the vehicle body may collide with the wheels.

Therefore, according to the present invention, the vertical displacements xB, xR, xP, xW of the vehicle body in each of the bounce, roll, pitch, and warp motion modes are determined from the detected vehicle height, and as shown in FIG. The vertical displacements xR, xW of the vehicle in each of the motion modes of the warp are considered from the vertical displacements xB, xR, xP, xW of the vehicle in consideration of the influence on the interference between the rear wheel 25 and the vehicle 20. A displacement xw exerted on each wheel support by each motion mode is determined. The ratio between the maximum value xwmx of the displacement amount xw of the four-wheel support portion and the operation limit (maximum bump amount) xbm of the hydraulic suspension mechanism, that is, the bump stop ratio kbm is obtained. Determine k1 to k6.

From the vehicle heights hFL, hFR, hRL and hRR detected by the vehicle height sensors 28 of the respective hydraulic suspension mechanisms 19, the vertical displacement amounts xB and xR of the vehicle body in the respective bouncing, roll, pitch and warp motion modes. , XP, xW are represented by the following equation (9).

XB = BF (hFL + hFR) + BR (hRL + hRR) xR = RF (hFL-hFR) + RR (hRL-hRR) xP = PF (hFL + hFR) -PR (hRL + hRR) xW = WF (hFL-hFR) -WR (hRL) −hRR) (9) where xB: Bounce displacement hFL: Detected vehicle height of left front wheel xR: Roll displacement hFR: Detected vehicle height of right front wheel xP: Pitch displacement hRL: Detected vehicle height of left rear wheel xW: Warp displacement hRR: Detected vehicle height of right rear wheel BF, BR: Bounce displacement force coefficient of front and rear wheels RF, RR: Roll displacement force coefficient of front and rear wheels PF, PR: Pitch displacement force coefficient of front and rear wheels WF, WR ： Warp displacement force coefficient of front and rear wheels Vertical displacement xB, xR, xP, xW in each motion mode of vehicle
Therefore, the displacement xw exerted on each wheel support by each motion mode of the vehicle body is expressed by the following equation (10).

XwFL = xB + xR + xP + xW xwFR = xB−xR + xP−xW xwRL = xB + xR−xP−xW xwRR = xB−xR−xP + xW (10) From the expressions (9) and (10), xwFL = M1F · hFL + MFL + M2F · hFL + M2F hRL + M4R · hRR xWFR = M2F · hFL + M1F · hFR + M4R · hRL + M3R · hRR xwRL = M3F · hFL + M4F · hFR + M1R · hRL + M2R · hRR xwRR = M4F · hFL + M1R + H1 + R1F + H1 + R1M
PR + WR M2F = BF-RF + PF-WF, M2R = BR-RR + PR-WR M3F = BF + RF-PF-WF, M3R = BR + RR-PR-WR M4F = BF-RF-PF + WF, M4R = BR-WR-R The maximum value xwmx of the displacement amount xw of is selected. If the maximum value xwmx is greater than 0, the maximum value xwm
The ratio kbm between x and the operation limit xbm is obtained, and the negative feedback gain coefficients k1 to k6 are determined from the bump stop ratio kbm, the bump stop coefficients kbs1 to kbs6, and the initial values kin1 to kin6 as in the following equation (12). I do.

[0027] ^{k1 = kin1 + kbs1 · kbm n} k2 = kin2 + kbs2 · kbm n k3 = kin3 + kbs3 · kbm n k4 = kin4 + kbs4 · kbm n k5 = kin5 + kbs5 · kbm n k6 = kin6 + kbs6 · kbm n ...... (12) However, kbm = | xwmx / Xbm | (absolute value, kbm <1) kbm: bump stop ratio xwbm: operation limit kin1 to kin6: initial value kbs1 to kbs6: bump stop coefficient (constant) n: any integer larger than 1 Note that the above maximum value When xwmx is smaller than 0, the bump stop ratio kbm is set to 0.

As shown in FIG. 4, according to the present invention, the vehicle height sensors 28 detect the vehicle heights hFL, hFR, hRL and hRR of the respective wheel supporting portions of the vehicle body 20 based on the above-described principle, and the lateral acceleration sensor 31 And the longitudinal acceleration sensor 32 detect the lateral acceleration g1 and the longitudinal acceleration g2 of the vehicle center of gravity. The relative displacement amount Δφ, Δ
Obtain θ and Δx.

The negative feedback gain coefficient k by which the relative displacement amount and the relative displacement speed are respectively multiplied by the negative feedback gain coefficient calculating means 30
Find 1 to k6. The relative displacement speed calculating means 34a calculates the relative displacement speeds φ ', θ', x 'of the vehicle body 20. The relative displacement amounts Δφ, Δθ,
Δx, lateral and longitudinal accelerations g1 and g2, and relative displacement speed φ ', θ
, X ′, the attitude control forces F11, F12, F of the vehicle body 20
Find 21, F22 and F32.

Next, the control oil amount calculating means 39 obtains control voltages VFL, VFR, VRL, VRR of the oil amount control valves 16 corresponding to the attitude control forces F11, F12, F21, F22, F32. The control voltage VFL,
The respective oil amount control valves 16 are controlled based on VFR, VRL, VRR and the feedback signal voltages VcFL, VcFR, VcRL, VcRR of the respective oil pressure sensors 17, and the oil amounts QFL, QFR, QRL, QRR of the respective hydraulic suspension mechanisms 19 are controlled. And the posture of the vehicle body 20 is maintained substantially flat (parallel to the road surface).

FIGS. 5 to 7 and 9 are flow charts of a control program for performing the above-described control by an electronic control unit composed of a microcomputer. This control program is repeatedly executed at predetermined time intervals. p11-p24, p41-p46, p31
-P39, p51-p57 represent each step of the control program. The control program is started at p11, initialization is performed at p12, and the output hydraulic pressure p is determined at p13 in the main hydraulic pressure monitoring routine shown in FIG.
m is kept at a predetermined value pc.

At p14, the relative vehicle heights hFL, hFR, hRL, hRR of the respective wheel supporting portions of the vehicle body are obtained from the vehicle height sensor 28, and the hydraulic pressures pFL, pFR, pR of the respective hydraulic suspension mechanisms 19 are obtained from the hydraulic pressure sensor 17.
L and pRR are read respectively, and each acceleration sensor 3 is read at p15.
From 1, 32, the lateral acceleration g1 of the vehicle body and the longitudinal acceleration g2
Respectively. The vertical displacement amounts xFL, xFR, xRL, xRR of the respective wheel supporting portions of the vehicle body are obtained at p16, and the relative displacement amounts Δφ, Δθ, Δx of the vehicle body are obtained at p17. At p18, the relative displacement speeds Δφ ′, Δθ ′, Δx ′ of the vehicle body are obtained. In step p19, a roll control force F11 during turning and a pitch control force F21 during acceleration / deceleration are determined.

At p20, the negative feedback gain coefficients k1 to k6 are obtained by the bump stop routine. At p21, the relative displacement amounts Δφ, Δθ, Δx of the vehicle body, the lateral and longitudinal accelerations g1, g2, and the negative feedback gain coefficients k1 to k6 are calculated. From this, the roll control force F12, pitch control force F22, and vertical displacement control force F32 during straight running are obtained.

At p22, control voltages VFL, VFR, VRL, VRR of the respective oil amount control valves 16 for keeping the vehicle body flat are obtained.
The amount of oil in each hydraulic suspension mechanism 19 is adjusted by the hydraulic suspension mechanism driving routine at p23, and the process ends at p24.

As shown in FIG. 6, the hydraulic pressure monitoring routine is p
Starting at 41, the output oil pressure pm of the hydraulic pump 4 is read at p42, and it is determined at p43 whether the output oil pressure pm is larger than the predetermined value pc. If the output oil pressure pm is smaller than the predetermined value pc, the process goes to p44. When the switching valve 12 is closed and the output oil pressure pm is larger than the predetermined value pc, the switching valve 12 is opened at p45 to lower the output oil pressure pm to maintain the predetermined value pc, and the program returns to the program at p46.

As shown in FIG. 7, the bump stop routine starts at p31, and the detected vehicle heights hFL, hFR, hR at p32.
The vertical displacements xB, xR, xP, of the vehicle in each of the bouncing, roll, pitch, and warp motion modes from L and hRR.
Find xW. At p33, the displacement amounts xwFL, xwFR, xwRL, xwRR of the respective wheel support portions of the vehicle body are obtained from the vertical displacement amounts xB, xR, xP, xW in the respective motion modes of the vehicle body. At p34, the maximum value xwmx is selected from the displacement amounts xwFL to xwRR. At p35, it is determined whether or not the maximum value xwmx of the displacement amounts xwFL to xwRR is larger than 0 (whether or not it is a thrust force to the hydraulic suspension mechanism 19). If the maximum value xwmx is smaller than 0, the bump stop ratio kbm is set to 0 at p36, and the process proceeds to p38. If the maximum value xwmx is larger than 0 at p35, the pump stop ratio kbm is determined at p37, the negative feedback gain coefficients k1 to k6 are determined at p38, and the program returns to the program at p39.

As shown in FIG. 9, the hydraulic suspension mechanism driving routine starts at p51, reads the hydraulic pressure p of each hydraulic suspension mechanism 19 from each hydraulic sensor 17 at p52, and reads the hydraulic pressure p at p53.
Is converted to a feedback voltage Vs. At p54, the excitation voltage Ve of each oil amount control valve 16 is obtained from the control voltage Vc and the feedback voltage Vs. At step p55, the oil amount control valve 16 is excited, and the oil amount Q for each hydraulic suspension mechanism 19 is adjusted.
The respective hydraulic suspension mechanisms 19 are driven at 56, and the program returns to the program at p57.

As shown in FIG. 8, each hydraulic suspension mechanism 19
Is adjusted by the excitation voltage Ve of each oil amount control valve 16.

As described above, even if the operation amount of the hydraulic suspension mechanism 19 due to excessive road surface input exceeds the operation limit xbm, the pump-stop ratio kbm only approaches 1, and the negative feedback gain coefficient k1 to k6 are (kin1 + kbs
1) Since the operation amount of the hydraulic suspension mechanism 19 is limited to the following range and the operation amount of the hydraulic suspension mechanism 19 is kept within the operation limit, the breakage of the hydraulic suspension mechanism 19 can be prevented. That is, regarding the negative feedback gain coefficient k1, as the operation amount of the hydraulic suspension mechanism 19 increases, FIG.
Kbm as shown in ⁿ approaches 1, k1 = kin1 + kbs
Approach 1 Therefore, if the initial value kin1 and the bump stop constant kbs1 are set in relation to the operation limit of the hydraulic suspension mechanism 19, the piston of the hydraulic suspension mechanism 19 will not collide with the cylinder end wall.

[0040]

As described above, according to the present invention, when an excessive road surface input is applied, the posture control force of each wheel supporting portion of the vehicle body corresponding to the relative displacement amount and the relative displacement speed of the vehicle body is calculated.
On the other hand, since the negative feedback gain coefficient for multiplying the relative displacement amount and the relative displacement speed of the vehicle body respectively corresponding to the displacement amount is continuously adjusted, the oil amount for the hydraulic suspension mechanism is limited to a predetermined value or less, and the hydraulic The operation amount of the suspension mechanism does not exceed the operation limit. Therefore, the piston of the hydraulic suspension mechanism does not collide with the cylinder end wall in response to an excessive road surface input, and does not generate abnormal noise or impact on the vehicle body.

Since the negative feedback gain coefficient for multiplying the relative displacement amount and the relative displacement speed of the vehicle body in accordance with the displacement amount is adjusted, a hydraulic suspension mechanism for independently suspending the front wheels and the rear shaft at both ends is provided. In a vehicle, the operation of the hydraulic suspension mechanism is unnecessarily limited in the roll and warp motion modes of the vehicle body, or the vehicle body collides with the wheels before the hydraulic suspension mechanism of the rear wheels does not reach the operation limit. There is no fear.

The amount of oil for the hydraulic suspension mechanism is continuously adjusted according to the road surface input, so that there is no sense of incongruity and the riding comfort of the vehicle is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a vehicle body attitude control device according to the present invention.

FIG. 2 is a hydraulic circuit diagram of a hydraulic suspension mechanism.

FIG. 3 is a flowchart of a control program of the control device.

FIG. 4 is a flowchart of a bump stop routine of a control program of the control device.

FIG. 5 is an explanatory diagram of a bump stop coefficient obtained by the bump stop routine.

FIG. 6 is a flowchart of a bump stop routine of a control program of the control device.

FIG. 7 is an explanatory diagram of a bump stop coefficient obtained by the bump stop routine.

FIG. 8 is a flowchart of a bump stop routine of a control program of the control device.

FIG. 9 is an explanatory diagram of a bump stop coefficient obtained by the bump stop routine.

FIG. 10 is a flowchart of a bump stop routine of a control program of the control device.

[Explanation of symbols]

19: hydraulic suspension mechanism 28: vehicle height sensor 30: negative feedback gain calculating means 31: lateral acceleration sensor 32: longitudinal acceleration sensor 34: relative displacement amount calculating means 34a: relative displacement speed calculating means 38: attitude control force calculating means 39 :
Control oil amount calculating means 40: Hydraulic suspension mechanism driving means

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60G 1/00-25/00

Claims (1)

(57) [Claims] 1. A relative displacement calculating means for calculating a roll displacement, a pitch displacement and a vertical displacement of a vehicle body based on a signal of a vehicle height sensor for detecting a vehicle height of each wheel, and a signal of a relative displacement calculating means. Control amount calculating means for obtaining the roll control torque F12, pitch control torque F22, and vertical displacement control force F32 of each wheel for keeping the vehicle body flat based on the following equation: An attitude control device for a vehicle body comprising: an oil amount calculating means for obtaining an oil amount of a suspension mechanism; and an oil amount control valve for adjusting the oil amount of each hydraulic suspension mechanism based on a signal from the oil amount calculating means. Δφ + k2 · Δφ '+ k7 · ∫Δφdt F22 = k3 · Δθ + k4 · Δθ ′ + k8 · ∫Δdt F32 = k5 · Δx + k6 · Δx ′ + k9 · ∫Δxdt where k1 to k6: negative feedback gain coefficient k7 to k9: constant Δφ: body Roll displacement Δθ: Displacement of vehicle body pitch Δx: Displacement of vehicle body vertical From the vehicle height detected by the vehicle height sensor provided in each hydraulic suspension mechanism, the vehicle body corresponding to each of the motion modes of bounce, roll, pitch, and warp of the vehicle by the following formula The vertical displacement amounts xB, xR, xP, xW of the respective wheel support portions are obtained as follows: xB = BF (hFL + hFR) + BR (hRL + hRR) xR = RF (hFL-hFR) + RR (hRL-hRR) xP = PF (hFL + hFR)- PR (hRL + hRR) xW = WF (hFL-hFR) -WR (hRL-hRR) where xB: bounce displacement xR: roll displacement xP: pitch displacement xW: warp displacement hFL: height of detected front left wheel hFR : Detected vehicle height of right front wheel hRL: Detected vehicle height of left rear wheel hRR: Detected vehicle height of right rear wheel BF, BR: Bounce displacement force coefficient of front and rear wheels RF, RR: Roll displacement force coefficient of front and rear wheels PF, PR : Coefficient of pitch displacement force of front and rear wheels WF, WR: Warp displacement force of front and rear wheels The coefficient xwFL = xB + xR + xP + xW xwFR = xB-xR + xP-xW xwRL = xB + xR-xP-xW xwRR = xB-xR-xP + xW The coefficient xwFL = xB + xR + xP + xW xwRL = xB-xR-xP + xW Coefficients k1 to k6 are given by the following equation: k = kin + kbs (xwmx / xbm) ⁿ , where kin is an initial value kbs is a constant xwmx: Maximum value of displacement amount for each motion mode of each wheel support xbm: Hydraulic suspension mechanism An attitude control device for a vehicle body, wherein the attitude control device obtains the vehicle body based on an operation limit.