JP2765311B2 - Active suspension - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active suspension and, more particularly, to an active suspension in which anti-roll control is performed according to a lateral acceleration generated in a vehicle body.

[0002]

2. Description of the Related Art An active suspension is disclosed, for example, in Japanese Patent Application Laid-Open No. 62-295714. Such an active suspension has a hydraulic cylinder interposed between a vehicle body and each wheel, and maintains the internal pressure of the hydraulic cylinder at a predetermined neutral pressure during non-rolling when the lateral acceleration generated in the vehicle is zero. The generated thrust bears part of the static load of the vehicle. When the vehicle enters a turning state from this non-roll state, the lateral acceleration is detected to cancel the roll moment due to the lateral load movement generated in proportion to the lateral acceleration of the vehicle body. By increasing the pressure and reducing the pressure of the turning inner wheel, an anti-roll moment is generated to suppress the roll or control the roll to a zero roll state.

By the way, assuming that the reaction force received from the road surface while the vehicle is turning is represented by a three-link model in which the suspension and the vehicle body are replaced by three virtual links, as shown in FIG. The force that supports the lateral movement of the tire is generated on the ground contact surface of the tire, and from this point a reaction force acts toward the roll center, but the vertical force of this reaction force turns On the outer wheel side, the force of pushing up the vehicle body (jack-up force) WU is obtained, and on the turning inner wheel side, the force of pulling down the vehicle body (jack-down force) WD is obtained. On the other hand, the vertical load of the turning outer wheel increases and the vertical load of the turning inner wheel decreases during the turning due to the lateral load movement, so that the cornering force CFO of the turning outer wheel is larger than the cornering force CFI of the turning inner wheel. Become. For this reason, the roll center is above the ground point,
When the angles of the left and right links are substantially equal due to roll suppression, the jack-up force WU becomes larger than the jack-down force WD, and the resultant force acts in the direction of lifting the vehicle body. This body lifting force increases with an increase in lateral acceleration during turning.

[0004] When the vehicle body lifting force is generated during turning as described above, a jack-up phenomenon occurs in which the entire vehicle body is lifted upward, and the camber angle and the toe angle are increased by extending the turning outer wheel beyond a predetermined stroke. On a changing or undulating road surface, the outer ring is completely extended, and the ground contact of the tire is reduced, so that the steering stability of the vehicle is reduced. For this reason, in a normal mechanical suspension, it is conceivable that the link arrangement is devised and the roll center is moved inward and downward according to the roll of the vehicle body to prevent the generation of the vehicle body lifting force. In the case of an active suspension that suppresses a roll, the roll center cannot be moved by the roll of the vehicle body. Therefore, in order to prevent the generation of a lifting force of the vehicle body, the present applicant has previously proposed an active suspension described later in Japanese Patent Application No. Hei 3-5722.

In this method, a hydraulic cylinder is inserted between a vehicle body and each wheel, and a coil spring is inserted in parallel with the hydraulic cylinder to reduce the internal pressure of the hydraulic cylinder during non-rolling when the lateral acceleration generated in the vehicle is zero. By maintaining the neutral pressure, a part of the static load of the vehicle is borne by the thrust generated by the hydraulic cylinder. When the vehicle turns from the non-roll state to the turning state, the lateral acceleration is detected to cancel the roll moment due to the lateral load movement generated in the vehicle body in proportion to the lateral acceleration. By increasing the pressure and reducing the pressure of the turning inner wheel, an anti-roll moment is generated to suppress the roll, or set to zero roll state, and at the same time, the neutral pressure is reduced with an increase in the lateral acceleration generated during turning I was trying to make it. That is, by lowering the neutral pressure according to the lateral acceleration during turning, the force for lifting the vehicle body is canceled, and the steering stability can be improved.

[0006]

However, since the jack-up force generated at the front and rear wheels depends on the lateral acceleration generated at each of the front and rear wheels, the front-rear neutral pressure varies according to the lateral acceleration at a predetermined point of the vehicle. Is reduced, there is a problem that the jack-up cannot be sufficiently suppressed in the turning transient state in which the lateral accelerations of the front and rear wheels are unbalanced.

SUMMARY OF THE INVENTION It is an object of the present invention to suppress the jack-up in a turning transient state in which the lateral accelerations of the front and rear wheels are unbalanced.

[0008]

To achieve the above object, according to the Invention The active suspensions according to the present invention, as shown in FIG. 1, a fluid cylinder interposed between the vehicle body and each wheel, wherein A control valve for individually controlling a working fluid for the fluid cylinder, a lateral acceleration detecting means for detecting a lateral acceleration acting on the vehicle body, and a roll for suppressing a roll of the vehicle body according to a detected lateral acceleration value of the lateral acceleration detecting means. A roll control means for outputting to the control valve a command value obtained by adding a roll suppression command value for generating an anti-roll moment and a neutral pressure command value for supporting at least a part of the vehicle static load to the control valve In the suspension, the lateral acceleration detecting means includes front and rear wheel axle lateral acceleration detecting means for detecting lateral acceleration on a vehicle front and rear axle, and the roll control means includes a front and rear wheel axle lateral acceleration detecting means. Based only on the lateral acceleration detection value of each of the front and rear wheel axis of the means, in accordance with an increase in the absolute value, di neutral pressure command value to the control valve provided in the front and rear wheels each vehicle
It is assumed that a neutral pressure command value correcting means for reducing the jack-up force so as to cancel it is provided.

[0009]

According to the present invention, each of the lateral accelerations on the front and rear wheel axles of the vehicle is detected by the front and rear wheel lateral acceleration detecting means, and based on only the detected lateral acceleration detection value on the front wheel axle, a neutral control provided in the roll control means is provided. The neutral pressure command value of the front wheel is corrected by the pressure command value correcting means, and the neutral pressure command value of the rear wheel is corrected by the neutral pressure command value correcting means provided in the roll control means based on only the detected lateral acceleration value on the rear wheel axle. Correct the value. That is, as the absolute value of the lateral acceleration detection value on each of the front and rear axles increases , the jack-up force is offset.
In this way, the neutral pressure command value is reduced, and thus the total command value obtained by adding the neutral pressure command value and the roll suppression command value is suppressed to a small value, thereby reducing the thrust generated in the fluid pressure cylinder of each of the front and rear wheels. Cancels the force generated in the direction of lifting the vehicle.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[0011] As shown in FIG.
6 is a hydraulic cylinder 18F as a fluid cylinder separately provided between the vehicle body side member 14 and each wheel side member 12.
L, 18FR, 18RL, 18RR, and pressure control valves 20FL, 20FR, 20R for adjusting the operating oil pressures of the hydraulic cylinders 18FL, 18FR, 18RL, 18RR, respectively.
L, 20RR, the hydraulic source 22 of the hydraulic system, the hydraulic source 22 and the pressure control valves 20FL, 20FR, 20RL, 2
Accumulators 24, 2 for accumulating pressure inserted between 0RR
4, a lateral acceleration sensor 26a provided forward LA from the center of gravity of the vehicle for detecting lateral acceleration acting in the lateral direction of the vehicle body;
Lateral acceleration sensor 26B provided LB behind the center of gravity of the vehicle
And pressure control valves 20FL, 20FR, 20RL, 20R
And a controller 30 as a roll control means for individually controlling the output pressure of R. The active suspension 16 includes hydraulic cylinders 18FL, 18FR,
Coil springs 36 mounted in parallel between the wheel side member 12 and the vehicle body member 14 for 8RL and 18RR.
And the hydraulic cylinders 18FL, 18FR, 18RL, 18
The RR includes a throttle valve 32 and an accumulator 34 for absorbing vibration that are individually connected to a pressure chamber L described later. here,
Each of the coil springs 36 has a relatively low spring constant and supports a static load of the vehicle body.

Hydraulic cylinders 18FL, 18FR, 18R
L and 18RR each have a cylinder tube 18a, and the cylinder tube 18a has a piston 18c.
The upper pressure chamber L closed by is formed. The upper end of the cylinder tube 18a is attached to the vehicle body-side member 14, and the lower end of the piston rod 18b is attached to the wheel-side member 12.

The pressure control valves 20FL, 20FR, 20
RL and 20RR each have a valve housing having a spool slidably housed in a cylindrical insertion hole (not shown);
It is formed in a pilot operation system having a proportional solenoid provided integrally with the valve housing. The supply port and the return port for the hydraulic oil of the pressure control valves 20FL, 20FR, 20RL, and 20RR are hydraulic piping 38,
The output port is connected to each of the hydraulic chambers 18FL, 18FR, 18RL, and 18RR via the hydraulic pipe 40 through the hydraulic oil supply side and the hydraulic oil return side of the hydraulic source 22 via 39. .

For this reason, by controlling the value of the exciting current i supplied to the proportional solenoid, the thrust by the exciting current i and the feedback pressure formed based on the control pressure on the output port side are balanced and adjusted. After all, the exciting current i
The control pressure PC corresponding to the hydraulic cylinder 18
FL, 18FR, 18RL, and 18RR can be supplied to the pressure chamber L. As shown in FIG. 3, the supply pressure PC outputs PMIN when the exciting current i is near zero,
When the exciting current i increases from this state in the positive direction, the exciting current i increases with a predetermined proportional gain K1, saturates at the line pressure PMAX of the hydraulic power source 22, and a neutral pressure command value V during non-rolling described later.
The neutral pressure PCN is reached at a neutral current value iN corresponding to N0.

As shown in FIG. 4, the lateral acceleration sensor 26a and the lateral acceleration sensor 26b have a voltage value proportional to the lateral acceleration that becomes positive when the vehicle is steered to the right from the straight running state and becomes negative when the vehicle is steered to the left. Lateral acceleration detection values GA, G
B is output.

As shown in FIG. 5, the controller 30
The lateral acceleration detection value GA of the lateral acceleration sensor 26a and the lateral acceleration detection value GB of the lateral acceleration sensor 26b are input, and the corresponding lateral acceleration calculation value GY of the vehicle center of gravity, the lateral acceleration calculation value GF on the front wheel axis, and the rear A lateral acceleration calculator 55 for calculating a lateral acceleration calculation value GR on the wheel axle and outputting the same, and a neutral pressure setting for inputting the lateral acceleration calculation value GF and outputting a neutral pressure command value VNF of a voltage corresponding thereto. A circuit 50F and a calculated value of the lateral acceleration GR are inputted, and a neutral pressure setting circuit 50R for outputting a neutral pressure command value VNR having a voltage corresponding thereto.
And the lateral acceleration calculation value GY is input and multiplied by the front wheel side roll suppression control gain KF and the rear wheel side roll suppression control gain KR to calculate the roll suppression command values VLF and VLR, and output these. Side and rear wheel side variable gain adjusters 52F and 52R, and the roll suppression command value V output from both variable gain adjusters 52F and 52R.
LF and VLR are individually input directly to one input side, and the neutral pressure command values V output from the neutral pressure setting circuits 50F and 50R.
NF and VNR are directly input to the other inputs, respectively, through adders 54FL and 54RL, and roll suppression command values VLF and VLR through sign inverters 56F and 56R for individually inverting the signs. Pressure command value VNF
And VNR are directly input to the other input side, respectively, and adders 54FL, 54F
R, 54RL, and 54RR, the addition command values output from the pressure control valves 20FL, 20FL,
There are provided drive circuits 58FL, 58FR, 58RL, 58RR which are formed of, for example, floating type constant voltage circuits which convert excitation currents iFL, iFR, iRL, iRR for the 0FR, 20RL, 20RR proportional solenoids and output them.

Here, the calculated lateral acceleration value 55 calculates the calculated lateral acceleration values GY, GF, GR from the input lateral acceleration detection values GA, GB by using the following arithmetic expressions. That is, heavy
There is a front wheel axle LF in front of the vehicle from the center point, and the vehicle is
If there is a rear axle in the rear LR, the mark in front of the center of gravity
If the sign is positive and the sign behind is negative, then GF = GA (LB- LF ) / (LB-LA) -GB (LA-LF) / (LB-LA) GR = GA (LB-LR) / ( LB-LA) -GB (LA-LR) / (LB-LA) GY = ( LBGA + LAGB ) / (LB-LA) .

[0018]

Further, each of the neutral pressure setting circuits 50F and 50R constitutes a neutral pressure command value correcting means, and the neutral pressure setting circuit 50F determines the neutral pressure command value V based on the calculated lateral acceleration value GF.
The neutral pressure setting circuit 50R outputs a neutral pressure set value V based on the calculated lateral acceleration GR.
It consists of a function generator that outputs NR. From the neutral pressure setting circuit 50F, as shown by the solid line in FIG.
When F is zero, it outputs a positive predetermined value VN0 for bearing a part of the static load of the vehicle body, and from this a neutral pressure command which gradually decreases as the lateral acceleration calculation value GF increases in the positive or negative direction. A value VNF is output from the neutral pressure setting circuit 50R, and a predetermined positive value VN0 for bearing a part of the static load of the vehicle body is output from the neutral pressure setting circuit 50R when the calculated lateral acceleration GR is zero as shown by the broken line in FIG. From this, the neutral acceleration command value VN gradually decreases as the lateral acceleration calculation value GR increases in the positive or negative direction, and its decreasing rate is smaller than the neutral pressure command value VNF on the front wheel side.
Output R.

Further, the front and rear wheel side variable gain adjusters 5
Roll suppression control gains KF and KR for 2F and 52R
Is set so that the roll generated on the vehicle body when the lateral acceleration is generated becomes substantially zero, and in this embodiment, KF>
Since it is set to KR, the load movement of the front left and right wheels becomes larger than the load movement of the rear left and right wheels,
The steering characteristic of the vehicle is set to the under steering characteristic.

The driving circuits 58FL, 58FR,
The excitation current i output from each of the pressure control valves 20FL, 20FR, 20RL,
It is individually input to 0RR.

Next, the operation will be described.

Now, it is assumed that the vehicle is traveling straight on a good road with no unevenness. In this straight running state, no lateral acceleration is applied to the vehicle body, so the lateral acceleration sensors 26a, 26a,
The lateral acceleration detection values GA and GB output from 6b are substantially zero, and the lateral acceleration calculation value GY is also substantially zero according to equation (1). Therefore, the neutral pressure command values VNF and VNR output from the neutral pressure setting circuits 50F and 50R of the controller 30 become positive predetermined values VN0, and the variable gain adjuster 52
Roll control pressure command value VL output from F and 52R
F and VLR become zero. Therefore, the adder 54FL,
The added outputs output from 54FR, 54RF, and 54RR all have a predetermined value VN0, and these are output to drive circuit 58F.
L, 58FR, 58RL, 58RR,
These drive circuits 58FL, 58FR, 58RL, 58R
Excitation currents iFL, iFR, iRL, i of neutral current value iN from R
RR is output. Therefore, each pressure control valve 20FL, 2FL
Control pressure PC output from 0FR, 20RL, 20RR
Becomes the neutral pressure PCN, and each hydraulic cylinder 18FL, 18F
The internal pressures of R, 18RL, and 18RR are also controlled to the neutral pressure PCN, so that the vehicle body maintains a predetermined vehicle height value and is kept flat.

When the vehicle shifts from a straight running state to a turning state on a good road, a lateral acceleration is generated in the vehicle body, and positive (or negative) lateral accelerations GA and GB corresponding to the lateral acceleration are obtained from the lateral acceleration sensors 26a and 26b. Is output to the lateral acceleration calculator 55, and the calculated lateral acceleration values GY, GF, G
R is output. Front-wheel and rear-wheel variable gain adjusters 5
As a result of inputting the lateral acceleration calculation value GY to 2F and 52R,
From the gain adjusters 52F and 52R, roll suppression command values VLF and VLR, which are values obtained by multiplying the calculated lateral acceleration value GY by the roll suppression control gains KF and KR, are output.

On the other hand, the calculated lateral acceleration value GF is input to the neutral pressure setting circuit 50F, and the calculated lateral acceleration value GR is input to the neutral pressure setting circuit 50R.
0F, 50R output neutral pressure command values VNF, VN
R decreases as the calculated lateral acceleration values GF and GR increase.

Therefore, assuming that the vehicle is in a right-turning state, the addition output output from the adder 54FL becomes positive to the positive neutral pressure command value VNF because the lateral acceleration calculation value GF is positive. Of the roll suppression pressure command value VLF is larger than the neutral pressure command value VNF by the roll suppression pressure command value VLF. Conversely, the addition output output from the adder 54FR is more negative than the neutral pressure command value VNF. Becomes smaller by the roll suppression pressure command value VLF. Similarly, the added output output from the adder 54RL is a positive neutral pressure command value VNR because the lateral acceleration calculation value GR is positive.
Is added to the positive roll suppression pressure command value VLR.
The value becomes larger by the roll suppression pressure command value VLR than the neutral pressure command value VNR. Conversely, the added output output from the adder 54RR becomes a value smaller by the negative roll suppression pressure command value VLR than the neutral pressure command value VNR. For this reason, the front left and rear left pressure control valves 20FL and 20RL corresponding to the turning outer wheel are provided.
Is increased from the neutral pressure PCN, and the control pressures PC output from the front right and rear right pressure control valves 20FR and 20RR corresponding to the turning inner wheel are decreased from the neutral pressure PCN. The outer cylinder side hydraulic cylinder 18FL,
18RL thrust increases and the hydraulic cylinder 1
The thrust of 8FR and 18RR is reduced, an anti-roll moment is generated, and the roll of the vehicle body is suppressed to maintain the vehicle body in a substantially flat state.

At this time, the neutral pressure command values VNF and VNR decrease as the lateral acceleration calculation value GY increases, so that the control pressures PCFL and 20FL output from the pressure control valves 20FL and 20RL on the turning outer wheel side on the pressure increasing side. PCRL is
As shown by the solid lines in FIGS. 7 and 8, the neutral pressures PNF and PNF corresponding to the neutral pressure command values VNF and VNR shown by the chain line.
The control pressures PCFR and PCRR output from the pressure control valves 20FR and 20RR on the turning inner wheel side, which become the pressure reducing side and conversely, become lower as the NR decreases, as shown by broken lines in FIGS. 7 and 8. The slope increases as the neutral pressures PNF and PNR decrease. As a result, an increase in pressure at the turning outer wheel is suppressed, and a decrease in pressure at the turning inner wheel is promoted. The average pressure of the left and right wheels also decreases with an increase in the lateral acceleration calculation value GY. Hydraulic cylinder 18FL, 18
The share of the static load due to the thrusts of FR, 18RL, and 18RR is reduced, and the jack-up force W described above is reduced.
The increase in U can be offset, the roll can be accurately suppressed, and the height of the center of gravity can be kept constant irrespective of the magnitude of the calculated lateral acceleration value GY.

In the present embodiment, the calculated lateral acceleration values GF and GR on the front wheel axle and the rear wheel axle are obtained, and the neutral pressures on the front wheel side and the rear wheel side are set in accordance with the respective calculated values. The neutral pressure of the front and rear wheels can be reduced according to each calculated value even during a turning transition in which the lateral accelerations on the upper and rear axles have different values, and the jack-up force on the front and rear wheels is reduced. WU can be effectively offset.

Here, in the present embodiment, the calculated lateral acceleration value GY is the detected lateral acceleration value at the center of gravity of the vehicle.
The present invention is not limited to this, and may be anywhere on any point of the vehicle.

Also, in the above embodiment, two lateral acceleration sensors are provided in the vehicle offset in the longitudinal direction to obtain lateral accelerations on the front and rear wheel axles, respectively, and the detection values from the respective lateral acceleration sensors are calculated. Although the lateral acceleration on the front and rear wheel axes was calculated by calculation, it is not limited to this,
For example, even if one lateral acceleration sensor and one yaw rate sensor are used, the lateral acceleration on the front and rear axles can be similarly calculated.

Further, in the above embodiment, each neutral pressure command value is corrected in accordance with the calculated value of the lateral acceleration on each of the front and rear wheel axles. I can't. That is, it is only necessary to know how much lateral acceleration is generated in the vicinity of the front and rear wheel axles. For example, one lateral acceleration sensor is provided in the vicinity of the front wheel axle, and one lateral acceleration sensor is provided in the vicinity of the rear axle. Alternatively, the neutral pressure command value to the control valve provided for each of the front and rear wheels may be corrected by directly using the respective detected values.

In the above embodiment, the front wheel side roll suppression control gain KF is changed to the rear wheel side roll suppression control gain KR.
The case where the steer characteristic of the vehicle is set to be an understeer characteristic by making it larger is described. However, the present invention is not limited to this. The roll suppression control gains KF and KR can be arbitrarily set according to the steer characteristic.

The jack-up force W generated on the turning outer wheel
Since U varies depending on the amount of load movement of the inner and outer turning wheels and the geometry of the suspension link system, the neutral pressure setting circuit 5
Neutral pressure command values VNF and VN set at 0F and 50R
The characteristics of R need to be set independently for the front and rear wheels according to the roll suppression control gain, suspension type, and the like. Specifically, when the front wheel roll control gain KF is set to be larger, it is necessary to make the change amount of the front wheel neutral pressure command value VNF larger.

Further, in the above-described embodiment, the case where an electronic circuit is applied as the controller 30 has been described. However, the present invention is not limited to this, and the arithmetic processing may be performed by using a microcomputer.

Further, in the above embodiment, the case where the pressure control valve is applied as the control valve to control the pressure of the actuator has been described. However, the present invention is not limited to this. The pressure of the actuator may be controlled by applying a control valve.

Further, in the above embodiment, the case where the working oil is used as the working fluid has been described. However, the present invention is not limited to this, and another fluid having low compressibility can be used.

[0037]

According to the present invention, the lateral acceleration on the longitudinal axis is detected, and based on only the detected value, the absolute value of the detected value is increased.
The control that lowers the neutral pressure of the front and rear wheels so that the jack-up force is offset , so even if the lateral acceleration that occurs on the front and rear wheel axles during turning transition becomes unbalanced, the jack-up that occurs on the front and rear wheels The power can be accurately offset and the vehicle lift can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a basic conceptual diagram showing an outline of the present invention.

FIG. 2 is a schematic configuration diagram showing one embodiment of the present invention.

FIG. 3 is an output characteristic diagram of a pressure control valve applicable to the present invention.

FIG. 4 is an output characteristic diagram of a lateral acceleration sensor applicable to the present invention.

FIG. 5 is a block diagram showing an example of a controller applicable to the present invention.

FIG. 6 is an output characteristic diagram of a neutral pressure setting circuit applicable to the present invention.

FIG. 7 is a characteristic diagram showing a relationship between a detected value of lateral acceleration and an internal pressure in a hydraulic cylinder on a front wheel side.

FIG. 8 is a characteristic diagram illustrating a relationship between a detected value of lateral acceleration and an internal pressure in a hydraulic cylinder on a rear wheel side.

FIG. 9 is a characteristic diagram similar to FIG. 7 in a conventional example.

FIG. 10 is a characteristic diagram similar to FIG. 8 in a conventional example.

FIG. 11 is an explanatory diagram showing a jack-up phenomenon due to a road surface reaction force in a conventional example.

[Explanation of symbols]

10FL, 10FR, 10RL, 10RR ... wheels, 12
... wheel-side members, 14 ... body-side members, 16 ... active suspensions, 18FL, 18FR, 18RL, 18RR ...
Hydraulic cylinder, 20FL, 20FR, 20RL, 20R
R: pressure control valve, 26a: lateral acceleration sensor (lateral acceleration detection means), 26b: lateral acceleration sensor (lateral acceleration detection means), 30: controller (roll control means), 50F, 50R: neutral Pressure setting circuit (neutral pressure correcting means), 52F: front wheel side variable gain adjuster, 52R
... Rear wheel variable gain adjuster, 54FL, 54FR, 54
RL, 54RR: adder, 55: lateral acceleration calculator (lateral acceleration detection means on front and rear wheels), 56F, 56R: inverter
58FL, 58FR, 58RL, 58RR ... Drive circuit.

Claims (1)

(57) [Claims] 1. A fluid cylinder interposed between a vehicle body and each wheel, a control valve for individually controlling a working fluid for the fluid cylinder, a lateral acceleration detecting means for detecting a lateral acceleration acting on the vehicle body, A roll suppression command value for generating an anti-roll moment for suppressing the roll of the vehicle body in accordance with the lateral acceleration detection value of the lateral acceleration detection means and a neutral pressure command value for supporting at least a part of the vehicle static load. A roll control unit that outputs the added command value to the control valve, wherein the lateral acceleration detection unit includes a front and rear wheel axle lateral acceleration detection unit that detects a lateral acceleration on a vehicle front and rear axle. The roll control means is based on only the lateral acceleration detection values on the front and rear wheel axes of the front and rear wheel axis lateral acceleration detection means ,
As the absolute value increases, the jack-up force offsets the neutral pressure command value to the control valve provided on each of the front and rear wheels of the vehicle.
An active suspension comprising neutral pressure command value correction means for decreasing the neutral pressure command value so as to reduce the pressure.