JPH069927B2 - Active suspension - Google Patents

Description

TECHNICAL FIELD The present invention relates to an active suspension capable of continuously changing roll rigidity or pitch rigidity of a vehicle.

[Conventional technology]

As a conventional active suspension, for example, the one described in Japanese Patent Laid-Open No. 52-79438 is known.

In this conventional active suspension, a hydraulic cylinder is provided between the vehicle body and the wheels, a relative displacement between the vehicle body and the wheels is detected by a stroke sensor, and the direction switching valve is switched based on the detected value to switch the hydraulic cylinder. By controlling the hydraulic pressure, the roll rigidity is finely adjusted according to the running condition.

[Problems to be Solved by the Invention]

However, in the above-mentioned conventional active suspension, since the hydraulic pressure supplied to and discharged from the hydraulic cylinder is switched by the directional control valve, a response delay occurs, vibration occurs when the directional control valve is switched, and a roll occurs. ，
There is an unsolved problem that it is not possible to smoothly perform the operation of suppressing the change in the posture of the vehicle body such as the pitch. Further, in normal control of the active suspension, in order to cancel the roll or pitch moment, control is performed to increase the spring constant and the damping constant. However, if the spring constant and the damping constant are increased in this way, for example, There is also an unsolved problem that the vibration input due to the unevenness of the road surface is directly transmitted to the vehicle body when passing through the unevenness of the road surface during the roll suppression control, which deteriorates the riding comfort.

Therefore, the present invention has been made by paying attention to the unsolved problem in the above-mentioned conventional example, and is excellent in responsiveness capable of suppressing the posture change due to the roll or pitch of the vehicle body without changing the spring constant and the damping constant. It is intended to provide an active suspension.

[Means for Solving the Problems]

In order to achieve the above object, the active suspension of the present invention, as shown in the basic configuration diagram of FIG. 1, includes a fluid pressure cylinder interposed between a vehicle body and each wheel, and a fluid pressure cylinder of this fluid pressure cylinder. A pressure control valve for controlling the working fluid pressure according to a command value, an acceleration detecting means for detecting at least one of lateral acceleration and longitudinal acceleration of the vehicle body, and a predetermined control gain for the acceleration detected value of the acceleration detecting means. Attitude change suppression command value calculating means for calculating an attitude change suppression command value for suppressing the attitude change of the vehicle body by multiplying, vehicle height detecting means for detecting the vehicle height at each wheel position, and the vehicle of the vehicle height detecting means. Vehicle height control command value calculating means for calculating a vehicle height control command value by performing control with a spring constant control gain and a damping constant control gain based on a deviation between a high detection value and a preset target vehicle height, and the attitude change. Suppression A control means for calculating the command value based on the attitude change suppression command value of the command value calculating means and the vehicle height control command value of the vehicle height control command value calculating means, and outputting the command value to the pressure control valve. There is.

[Action]

When lateral acceleration or longitudinal acceleration occurs in the vehicle body, this is detected by the acceleration detecting means, and the attitude change suppression command value calculating means multiplies the detected acceleration value by a predetermined control gain to suppress the attitude change caused by the roll or pitch in the vehicle body. The posture change suppression command value is calculated.

On the other hand, the vehicle height value at each wheel position of the vehicle is detected by the vehicle height detection means, and the vehicle height command value calculation means obtains a deviation between the vehicle height detection value and a preset target vehicle height, and the spring constant control Gain and damping constant control The vehicle height command value for maintaining the vehicle height at the target vehicle height is calculated by controlling the gain.

Then, a command value for the pressure control valve is calculated based on the attitude change suppression command value and the vehicle height command value calculated by the control means, and this is output to the pressure control valve to maintain the vehicle height at the target vehicle height. At the same time, roll or pitch due to lateral acceleration or longitudinal acceleration is suppressed. At this time, the attitude change suppression command value that suppresses the attitude change of the vehicle due to the roll or the pitch is
The spring constant control gain and the damping constant control gain are not included to prevent an increase in the amount of transmission of vibration input from the road surface to the vehicle body during posture change suppression control.

〔Example〕

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

2 to 5 show an embodiment of the present invention.

In FIG. 2, 1FL, 1FR, 1RL and 1RR are active suspensions interposed between the vehicle body side member 2 and the wheel side member 4 which individually supports the wheels 3FL, 3FR, 3RL and 3RR, respectively. A pressure control valve for controlling the hydraulic pressures of the hydraulic cylinders 5FL to 5RR, the coil springs 6FL to 6RR, and the hydraulic cylinders 5FL to 5RR as fluid pressure cylinders in response to only a command value from a control device 30 described later. It has 7FL to 7RR.

Here, in each of the hydraulic cylinders 5FL to 5RR, the cylinder tube 5a thereof is attached to the wheel side member 4, the piston rod 5b is attached to the vehicle body side member 2, and the operating hydraulic pressure in the pressure chamber 19 closed by the piston 5c. Are controlled by pressure control valves 7FL to 7RR. The coil springs 6FL to 6RR and the hydraulic cylinders 5FL to 5RR are mounted in parallel between the vehicle body side member 2 and the wheel side member 4 to support the static load of the vehicle body. The coil springs 6FL to 6RR may have a low spring constant that only supports the static load of the vehicle body.

The pressure control valves 7FL to 7RR are supplied with command values Ia to Id from the control device 30 that output command values for suppressing the posture change of the vehicle body based on the lateral acceleration and the longitudinal acceleration of the vehicle, and these command values Ia to Id are supplied. The control pressures corresponding to the above are output individually, and these are individually supplied to the hydraulic cylinders 5FL to 5RR constituting the active suspension interposed between each wheel and the vehicle body, and the biasing force against the posture change of the vehicle body is exerted. Generate. As shown in FIG. 3, the specific structure of the pressure control valve 7 includes a cylindrical valve housing 11 and a proportional solenoid 12 integrally provided with the valve housing 11. An upper insertion hole 11U in FIG. 3 and a lower insertion hole 11L in FIG. 3 defined by a partition wall 11A having a valve seat 11a having a predetermined diameter are coaxially formed in the central portion of the valve housing 11. ing. In addition, at a lower position above the insertion hole 11L and separated from the partition wall 11A by a predetermined distance, the fixed diaphragm 13 is provided.
Is provided, whereby a pilot chamber C is formed between the fixed throttle 13 and the partition wall 11A. Further, on the lower side of the fixed throttle 13 in the insertion hole 11L, the main spool 14 is slidably disposed in the axial direction, the upper and feedback chamber F _U is below the main spool 14
And _FL are respectively formed, and the main spool 14
The upper and lower ends feedback chamber _F U, respectively arranged offset spring 15A to _{F L,} is regulated by 15B. The input port 11i, the control port 11n, and the drain port 11o are formed in this order in communication with the insertion hole 11L, the input port 11i is connected to the hydraulic oil supply side of the hydraulic source 24 via the hydraulic pipe 25, and the drain port 11o is It is connected to the drain side of the hydraulic power source 24 via the hydraulic pipe 26, and the control port 11n is connected to the pressure chamber 19 of the hydraulic cylinders 7 _{FL to} 7 RR via the hydraulic pipe 27.

The main spool 14 includes a land 14a facing the input port 11i and a land 1 facing the drain port 11o.
And 4b, includes both these lands 14a, a pressure chamber 14c comprising an annular groove formed between 14b, and a pilot passage 14d for communicating the feedback chamber F _L of the pressure chamber 14c and a lower side.

In the upper insertion hole 11U, a poppet 16 is axially slidably arranged with its valve portion facing the valve seat 11a. The poppet 16 allows the insertion hole 11U to move in two chambers in the axial direction. And the flow rate of the working oil flowing through the valve seat 11c, that is, the pressure in the pilot chamber C can be adjusted.

Further, the input port 11i is connected to the pilot passage 11s.
The drain port 11o is communicated with the insertion hole 11U through a drain passage 11t.

On the other hand, the proportional solenoid 12 includes an axially slidable plunger 17 and a poppet 16 of the plunger 17.
It has an actuator 17A fixed to the side and an exciting coil 18 for driving the plunger 17 in its axial direction. The exciting coil 18 is appropriately excited by a command value I which is a direct current from the control device 30. To be done. As a result, the movement of the plunger 17 controls the position of the poppet 16 via the actuator 17A to control the flow rate passing through the communication hole 11A. In a state where the pressing force by the proportional solenoid 12 is added to the poppet 16, feedback chamber F _L, the pressure of both F _U are balanced, the spool 14 is input to the control port 11n In the neutral position the port The connection between 11i and the drain port 11o is cut off.

Here, the relationship between the command value I and the control oil pressure P _C output from the control port 11n is as shown in FIG.
There outputs P _MIN when it is close to zero, the command value I is increased in a positive direction from this state, into a predetermined proportional gain K ₁ with a control output P _C is increased, the line pressure of the hydraulic source 24 P Saturate with _L.

In FIG. 2, 28H is a pressure control valve 7FL or 7RR.
The high-pressure side accumulator 28L connected in the middle of the hydraulic pipe 25 between the hydraulic pressure source 24 and the hydraulic source 24 communicates with the hydraulic pipe 27 between the pressure control valves 7FL to 7RR and the hydraulic cylinders 5FL to 5RR via the throttle valve 28V. It is a low voltage side accumulator.

On the other hand, on the vehicle body, a lateral acceleration detector 31 as a lateral acceleration detecting means for detecting a lateral acceleration occurring in the vehicle body, and a longitudinal acceleration detecting means as a longitudinal acceleration detecting means for detecting a longitudinal acceleration occurring in the vehicle body. A device 32 is provided in each place, and the detected acceleration value of the lateral acceleration detector 31 and the detected longitudinal acceleration value of the longitudinal acceleration detector 32 are supplied to the control device 30.

Further, stroke sensors 33FL to 33RR for detecting displacements of the fluid pressure cylinders 5FL to 5RR are provided at appropriate places of the fluid pressure cylinders 5FL to 5RR, and detection signals SFL to SRR of these stroke sensors 33FL to 33RR are provided.
Are supplied to the control device 30.

Further, as shown in FIG. 5, the control device 30 controls the active suspensions 1FL to 1RR so that the vehicle attitude becomes appropriate.
An adder for calculating a deviation between the positive inputs of the vehicle height signals HFL to HRR of the vehicle height setter 34 and the inverted inputs of the detection signals SFL to SRR of the stroke sensors 33FL to 33RR which are separately output. 35FL to 35RR, and these adders 3
The deviation outputs of 5FL to 35RR are supplied to amplifiers 36FL to 36 which multiply predetermined gains K _{a1 to} K _a4 for performing proportional control, and are also supplied to differentiators 37FL to 3RR for performing differential control to differentiate the differentiators 37FL to 37RR. output is fed to an amplifier 38FL~38RR multiplying a predetermined gain _C 1 -C ₄ thereto,
Outputs of these amplifiers 38FL to 38RR and the amplifier 36FL
The outputs of ~ 36RR are added by adders 39FL-39RR and output as a vehicle height command value for maintaining the target vehicle height as the vehicle height. Here, the amplification degree K of the amplifiers 36FL to 36RR
_{Since a1 to} K _a4 correspond to the spring constant of the suspension and the amplification degrees C _{1 to} C _{4 of the} amplifiers 38FL to 38RR correspond to the damping constant of the suspension, the suspension characteristics of the vehicle can be set by appropriately setting these amplification degrees. Can be changed. Then, the vehicle height setting device 34 and the adder 3
5FL-35RR, amplifier 36FL-36RR, differentiator 37FL-
37RR, amplifiers 38FL to 38RR, and adders 39FL to 39
The target command value calculation means is configured by the RR.

Further, the control device 30 is configured so that the lateral acceleration detector 31
Front wheel side variable amplification amplifier 40f and rear wheel side variable amplification amplifier 40r, to which the lateral acceleration detection value is inputted, and front wheel side variable amplification amplifier 41f to which the longitudinal acceleration detection value of the longitudinal acceleration detector 32 is inputted. The rear wheel side variable gain amplifier 41r is provided, and these variable gain amplifiers 4r are provided.
0f, 40r, 41f, 41r amplification degrees K _bf , K _br ,
K _cf and K _cr can be arbitrarily changed by the driver operating the roll rigidity distribution adjuster 42 and the pitch rigidity distribution adjuster 43 as the rigidity distribution adjusting means provided in the driver's seat. The distribution can be adjusted appropriately, and the roll rigidity distribution adjuster 42 sets the sum of the amplification degrees K _bf and K _br so that the roll moment generated in the vehicle body by the lateral acceleration is canceled, and the pitch rigidity distribution adjustment is performed. The device 43 sets the sum of the amplification factors K _cf and K _cr so that the pitch moment generated in the vehicle body by the longitudinal acceleration is canceled.

Then, an adder 44FL for adding the inverting input of the variable gain amplifier 40f and the positive input of the variable gain amplifier 41f, and the positive input of variable gain amplifier 40f and the variable gain amplifier 44f.
An adder 44FR that adds the positive input of f, an adder 44FR that adds the inverting input of the variable amplification amplifier 40r and the positive input of the variable amplification amplifier 41r, and the variable amplification amplifier 40r
And an adder 44RR for adding the positive input of the variable gain amplifier 44r and the positive input of the variable gain amplifier 44r.
FL to 44RR and the variable amplification amplifiers 40f, 40r,
The pressure estimating means of the present invention is constituted by 41f and 41r.

On the other hand, the outputs of the adders 35FL to 35RR, that is, the vehicle height signals HFL to HRR and the stroke sensor output signal SFL to.
A vehicle height adjustment circuit 45FL for forcibly adjusting the hydraulic pressure when the difference from the SRR continues to be greater than a predetermined value for a predetermined time or more.
.About.45RR, the outputs of the vehicle height adjusting circuits 45FL to 45RR, the outputs of the adders 39FL to 39RR, and the outputs of the adders 44FL to 44RR are added, and the added value is added to each pressure control valve 7FL. Adders 46FL to 46RR for outputting the command values Ia to Id of 7RR are provided, and the converters 46FL to 46FL to
46RR constitutes the command value control means of the present invention.

Next, the operation of the above embodiment will be described.

Now, assuming that the vehicle is traveling at a constant vehicle speed on a flat road with no unevenness on the road surface, in this state, no roll or pitch has occurred in the vehicle body, and therefore the lateral acceleration of the lateral acceleration detector 31. The detected value and the longitudinal acceleration detected value of the longitudinal acceleration detector 32 are both zero. Therefore, the outputs of the variable amplification amplifiers 40f, 40r, 41f, 41r become zero, and accordingly, the outputs of the adders 44FL to 44RR also become zero. Further, in this state, each hydraulic cylinder 5FL to 5FL
Since no vibration is input to RR, the output signals SFL to SRR of each stroke sensor are all zero, and each adder 46FL to
46RR includes vehicle height signals HFL to HRR from the vehicle height setting device 34.
Multiplied by a predetermined gain K _{a1 to} K _a4 and the vehicle height signal HFL
By differentiating the ~HRR only the sum of the value obtained by multiplying a predetermined gain C ₁ -C ₄ is input, this value as a command value Ia～Id, is output to the pressure control valve 7FL～7RR. Therefore,
Since the hydraulic pressures of the hydraulic cylinders 5FL to 5RR are maintained at a predetermined pressure that provides an appropriate vehicle height, the posture of the vehicle body is maintained in a suitable state.

Therefore, in this state, the feedback bag chambers _HL , F of the pressure control valves 7FL-7RR are applied to the vibration input of a relatively low frequency input from the road surface through the wheels 3FL-3RR.
The vibration is absorbed by the movement of the spool 14 due to the pressure fluctuation of _U , and the throttle valve 28V is applied to the vibration input of a relatively high frequency corresponding to the unsprung resonance frequency due to the fine unevenness of the road surface.
The vibration transmission rate to the vehicle body is reduced, and good riding comfort can be secured.

Here, a case will be described in which the vehicle is braking, longitudinal acceleration is generated in the vehicle body, and a pitch moment is generated in the vehicle body in the direction in which the front wheel side sinks.

That is, when the vehicle brakes, the longitudinal acceleration detecting means 32
Detects a positive longitudinal acceleration (in this case, the acceleration generated during vehicle braking is positive) and outputs the detected value to the control device 30. On the other hand, since lateral acceleration does not occur in the vehicle body, the lateral acceleration detection value remains zero.

Then, the outputs of the variable amplification factor amplifier 41f and the variable amplification factor amplifier 41r increase in the positive direction, and accordingly, the outputs of the adders 44FL and 44FR increase in the positive direction and the outputs of the adders 44RL and 44RR decrease in the negative direction. Increase to.

On the other hand, due to the pitch moment, the hydraulic cylinder 5FL
Stroke sensor 33FL to 33RR
Detects the displacement, and the detection signals SFL to SRR are supplied to the adders 35FL to 35RR. In this case, since the hydraulic cylinders 5FL, 5FR on the front wheel side fluctuate in the contracting direction (negative direction), the displacement is fed back to the adders 35FL, 3FR.
The output of 5FR increases, and the hydraulic cylinder 5R on the rear wheel side
Since L and 5RR fluctuate in the extending direction (positive direction), the output of the adders 35RL and 35RR whose displacement is fed back decreases. Then, the target command values based on the output values of these adders 35FL to 35RR are changed to amplifiers 36FL to 36R.
R, differentiators 37FL to 37RR, amplifiers 38FL to 38RR, and adders 39FL to 39RR are calculated.

As a result, the command values Ia and Ib output from the adders 46FL and 46FR become relatively large, and the adder 46
The command values Ic and Id output from the RL and 46RR are relatively small values. Therefore, the front wheel side pressure control valves 7FL, 7FL
Since FR increases the pressure in the pressure chamber 19 of the hydraulic cylinders 5FL and 5FR, it is difficult for the piston 5c to descend and the front of the vehicle body is prevented from sinking, and the rear wheel side pressure control valves 7RL and 7RR are , Pressure chamber 1 of hydraulic cylinders 5RL, 5RR
Since the pressure of 9 is lowered, it is difficult for the piston 5c to rise and the rear portion of the vehicle body is prevented from floating. Therefore, even when the vehicle is being braked, the pitch moment generated in the vehicle body is canceled out, so that the attitude of the vehicle body is prevented from being greatly changed, and the vehicle body attitude is maintained appropriately.

Further, when the vehicle suddenly starts or accelerates and longitudinal acceleration in the opposite direction is generated, and a pitch moment in the direction in which the rear wheel side sinks is generated in the vehicle body, the longitudinal acceleration detector 3
Since 2 detects negative longitudinal acceleration, the adder 4 on the front wheel side
The outputs of 4FL and 44FR increase in the negative direction, and the outputs of the adders 44RL and 44RR on the rear wheel side increase in the positive direction.
Since the front wheel hydraulic cylinders 5FL and 5FR move in the extending direction (forward direction), the output of the adders 35FL and 35FR, whose displacement is fed back, increases, and the rear wheel hydraulic cylinders 5RL and 5RR contract. Since it moves in the direction (negative direction), its displacement is fed back to the adder 35R.
The output of L and 35RR decreases. Therefore, the command values Ia, I
Since b is a relatively small value and command values Id and Ic are relatively large values, the front wheel side pressure control valves 7FL and 7FR are
Reduces the pressure in the pressure chambers 19 of the hydraulic cylinders 5FL and 5FR to prevent the piston 5c from rising easily and prevent the front portion of the vehicle body from floating, and the pressure control valve 7 on the rear wheel side is provided.
The RL and 7RR increase the pressure in the pressure chamber 19 of the hydraulic cylinders 5RL and 5RR and prevent the piston 5c from being lowered easily so that the rear part of the vehicle body is prevented from sinking. Therefore, when the vehicle suddenly starts or suddenly accelerates. However, the pitch moment generated in the vehicle body is canceled, and the posture of the vehicle body is maintained in a suitable state.

Next, a case will be described in which the steering wheel is turned to the right from the vehicle straight traveling state to the right turning state.

When the vehicle turns right, lateral acceleration that increases to the left is generated in the vehicle body, so a roll moment is generated in the vehicle body in the direction in which the left side of the vehicle body sinks, and the lateral acceleration detector 3
1 detects the lateral acceleration in the negative direction (in this case, the lateral acceleration generated when the vehicle turns left) is positive. Then,
Stroke sensors 33FL, 33RL on the left side of the vehicle body detect negative displacements and stroke sensors 33FR, 3 on the right side of the vehicle body
Since 3RR detects a positive displacement, the target command value on the left side of the vehicle body becomes a relatively large value, and the target command value on the right side of the vehicle body becomes a relatively small value.

On the other hand, the lateral acceleration detection value is the amplification variable amplifier 40f,
It is supplied to 40r and amplified, and the amplified value is inverted to the adders 44FL and 44RL on the left side of the vehicle body,
Positive inputs are made to the adders 44FR and 44RR on the right side of the vehicle body.

As a result, the outputs of the adders 46FL and 46RL have a relatively large value, and the outputs of the adders 46FR and 46RR have a relatively small value. Therefore, the pressure control valves 7FL and 7RL on the left side of the vehicle body receive the pressure of the hydraulic cylinders 5FL and 5RL. Since the pressure in the chamber 19 is increased, it is difficult for the piston 5c to descend and the left side of the vehicle body is prevented from sinking, and the pressure control valve 7F on the right side of the vehicle body is prevented.
Since R and 7RR lower the pressure in the pressure chamber 19 of the hydraulic cylinders 5FR and 5RR, it is difficult for the piston 5c to rise and the right side of the vehicle body is prevented from floating. Therefore, even when the vehicle is turning, it is possible to prevent the roll moment generated in the vehicle body from being canceled and the posture of the vehicle body to be largely changed, so that the posture of the vehicle body is preferably maintained.

Even when the vehicle makes a left turn, the roll moment generated in the vehicle body is canceled by the same action as described above, and the posture of the vehicle body can be appropriately maintained.

Further, if the vehicle height is not appropriate due to a change in the posting state or the like for a predetermined time or more, the vehicle height adjusting circuits 45FL to 45FL
RR forcibly increases or decreases the vehicle height by an adder 46
Since a predetermined value is output to FL to 46RR, command values Ia to I
The vehicle height can be set to an appropriate state by appropriately increasing or decreasing d.

Further, even if lateral acceleration and longitudinal acceleration occur simultaneously on the vehicle body, such as when acceleration or braking is applied when the vehicle turns, in the above embodiment, the value obtained by multiplying each acceleration by a predetermined gain is a positive value. Since the input values or the inverted inputs are added and the addition is made, the command values Ia to Id are set so as to cancel the roll moment and the pitch moment, and those moments generated in the vehicle body are canceled by the action of the hydraulic cylinders 5FL to 5RR. , The posture of the vehicle is maintained properly.

As described above, in the above embodiment, the fluid pressure of each fluid pressure cylinder that can balance the roll moment and the pitch moment generated in the vehicle body is estimated based on the lateral acceleration and the longitudinal acceleration that cause the posture change of the vehicle body, This estimated pressure and a target designated value for maintaining an appropriate vehicle height obtained from the stroke of the hydraulic cylinder, etc. are added, and the pressure control valve is operated by the added value. The hydraulic cylinder operates with good responsiveness to cancel the change before the posture of the vehicle body greatly changes. Therefore, even if the vehicle turns, brakes or accelerates and various moments are generated in the vehicle body. A large change in posture is prevented.

Here, the rigidity at the time of balancing with the roll moment and pitch moment generated in the vehicle body, that is, the degree of canceling each moment can be arbitrarily changed by the rigidity distribution mechanism, such as the roll characteristic and the pitch characteristic desired by the driver. The suspension characteristics can be selected.

In the above embodiment, the roll moment and the pitch moment can be canceled regardless of the setting states of the gains K _{a1 to} K _a4 corresponding to the spring constant of the suspension and the gains C _{1 to} C ₄ corresponding to the damping constant. From
These gains K _{a1 to} K _a4 , so that the ride comfort is good,
Even if C _{1 to} C ₄ are set to be small so that vibrations due to small irregularities on the road surface are not transmitted to the vehicle body, the responsiveness of the posture change prevention to the roll moment and the pitch moment is not impaired.

In the above embodiment, the case where the hydraulic cylinder is applied as the fluid pressure cylinder has been described, but the present invention is not limited to this, and other fluid pressure cylinders such as a pneumatic cylinder can be applied.

〔The invention's effect〕

As described above, in the active suspension of the present invention, the acceleration detection means for detecting at least one of the lateral acceleration and the longitudinal acceleration occurring in the vehicle body is provided, and the acceleration detection value of this acceleration detection means is provided. A posture change suppression command value for suppressing a posture change due to a roll or a pitch occurring on the vehicle body is calculated from the above, and the vehicle height at each wheel position is detected by the vehicle height detecting means. Since the vehicle height command value is calculated by performing control with the spring constant control gain and the damping control gain, and the command value for controlling the pressure control valve based on the posture change suppression command value and the vehicle height command value is obtained, Even if the vehicle turns, brakes or accelerates and rolls or pitches on the vehicle body to change its posture, the pressure control valve and fluid pressure cylinder operate with good responsiveness. Since the posture change can be controlled accurately, and the spring constant and damping constant of the suspension can be set independently of the above responsiveness, these spring constants and damping constants can be set small. The effect that the vibration input due to the unevenness of the road surface is hardly transmitted to the vehicle body and the riding comfort can be improved without impairing the responsiveness is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing the basic configuration of the present invention, FIG. 2 is a configuration diagram of an embodiment of the present invention, FIG. 3 is a sectional view showing an example of a pressure control valve, and FIG. 4 is FIG. Is a graph showing the relationship between the command value of the pressure control valve and the output pressure, and FIG. 5 is a block diagram showing an example of the control device. 1FL to 1RR ... Active suspension, 2 ... Body side member,
3FL ~ 3RR ... Wheels, 5FL ~ 5RR ... Hydraulic cylinder, 6FL ~
3RR ... Coil spring, 7FL to 7RR ... Pressure control valve, 3
0 ... Control device, 31 ... Lateral acceleration detector, 32 ... Longitudinal acceleration detector, 34 ... Vehicle height setting device, 33FL-33RR ... Stroke sensor, 40f, 40r, 41f, 41r ... Variable amplification amplifier. , 42 ... Roll rigidity distribution adjuster (rigidity distribution adjusting means), 43 ... Pitch rigidity distribution adjuster (rigidity distribution adjusting means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Fukunaga 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Masaharu Sato 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. ( 56) References JP-A-62-295714 (JP, A)

Claims (1)

[Claims] 1. A fluid pressure cylinder interposed between a vehicle body and each wheel, a pressure control valve for controlling a working fluid pressure of the fluid pressure cylinder according to a command value, and a lateral acceleration of the vehicle body or a longitudinal acceleration. An acceleration detecting means for detecting at least one of accelerations, and an attitude change suppressing command for calculating an attitude change suppressing command value for suppressing an attitude change of a vehicle body by multiplying an acceleration detected value of the acceleration detecting means by a predetermined control gain. Value calculation means, vehicle height detection means for detecting the vehicle height of each wheel position,
A vehicle height control command value for calculating a vehicle height control command value by performing control with a spring constant control gain and a damping constant control gain based on a deviation between the vehicle height detection value of the vehicle height detection means and a preset target vehicle height Calculating means, based on the attitude change suppression command value of the attitude change suppression command value calculating means and the vehicle height control command value of the vehicle height control command value calculating means, and calculating the command value to the pressure control valve. An active suspension comprising a control means for outputting.