JPH06219130A - Vehicle suspension device - Google Patents

Abstract

PURPOSE:To restrain transitional rolling, and secure comfortableness to ride in without causing delay in control or a difference in the control timing by restraining reliably extending and contracting speed and a stroke on the stroke side of respective shock absorbers corresponding to the actual rolling direction. CONSTITUTION:A shock absorber (b) having a damping coefficient changing means (a) is arranged between a vehicle body and a wheel. By the way, vehicle behavior, a steering changing condition and a rolling condition are detected respectively by respective detecting means (c, d and e). When a detected value of the steering changing condition is less than a prescribed value, the damping coefficient changing means (a) is controlled by a control part (f) of a control means (g) according to a detected value of the vehicle behavior so as to control the shock absorber (b) optimally. In this case, a rolling control part (h) of the control means (g) controlls it so that the pressure side of the shock absorber (b) on the rolling directional side and the extension side of the shock absorber (b) on the anti-rolling directional side have respectively a high damping coefficient until at least prescribed time passes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension system for controlling a damping coefficient of a shock absorber provided between a sprung part and an unsprung part of a vehicle, and more particularly to a device for controlling roll restraint during steering.

[0002]

2. Description of the Related Art Conventionally, as such a vehicle suspension system, for example, one disclosed in Japanese Utility Model Laid-Open No. 59-117510 is known.

In this vehicle suspension system, when the level is high, the damping coefficient of the shock absorber and the spring constant of the air spring are determined according to the level of the lateral acceleration detected by the vehicle lateral acceleration sensor which detects the acceleration applied in the vehicle width direction. By performing roll control to increase at least one of them and keep them in a hard state, it is possible to suppress the transient roll of the vehicle body that occurs due to a sudden steering operation and ensure the steering stability of the vehicle. It was a thing.

[0004]

However, in such a conventional vehicle suspension system, since the hard state is maintained during roll control, a rough road can be maintained during roll control. When traveling, there was a problem that unsprung vibration was transmitted to the vehicle body and the riding comfort was significantly deteriorated.

The present invention has been made in view of such a problem, and provides a vehicle suspension device capable of suppressing a transient roll due to abrupt steering and ensuring a riding comfort during roll control. The purpose is to do.

[0006]

In the present invention, as shown in the claim correspondence diagram of FIG. 1, one of the extension side and the compression side, which is provided between the vehicle body and each wheel, has a high damping coefficient side. A shock absorber b having a damping coefficient changing means a having a structure in which the reverse stroke side has a low damping coefficient when controlled to
Vehicle behavior detection means c for detecting factors relating to vehicle behavior
And steering state detection means d for detecting the steering state of the vehicle,
Roll state detection means e for detecting the roll state of the vehicle,
When the detected value detected by the steered state detecting means d is less than a predetermined threshold value, each shock absorber b is controlled to an optimum damping coefficient based on the detected value detected by the vehicle behavior detecting means d. In order to do so, a control means g having a damping coefficient control section f for outputting a switching signal to the damping coefficient changing means a, and a detection value provided by the control means g and detected by the steering state detecting means d have a predetermined threshold value. When the value is equal to or more than the value, the shock absorber b is located on the inner wheel side with respect to the turning direction for a predetermined time
Each damping coefficient changing means a so that the compression side of the shock absorber b, which is the extension side and the outer ring side, has a high damping coefficient.
A switching signal is output to the roll direction shock absorber b until the predetermined time elapses and the roll direction is detected based on the roll direction detected by the roll state detection means e. The roll control unit h outputs a switching signal to each damping coefficient changing means a so that the extended side of b has a high damping coefficient. In addition, the roll direction here means a direction on the side where the vehicle body sinks when the vehicle rolls, and is opposite to the steering direction.

[0007]

The function of the present invention will be described. The reference numerals in the description correspond to those in FIG. When the steering operation is performed while the vehicle is running, the vehicle body rolls. At this time, when the detected value detected by the steering state detecting means d is less than the predetermined threshold value, the roll generated by the steering is also small, so the roll controller h does not operate and the damping coefficient controller At f, a switching signal is output to the damping coefficient changing means a so as to control the shock absorber b to the optimum damping coefficient based on the signal from the vehicle behavior detecting means c, whereby the vehicle during straight running or steady turning is output. The ride comfort and steering stability of the car are secured.

Further, when the detected value detected by the steering state detecting means d is equal to or more than a predetermined threshold value, a large amount of roll is generated on the vehicle body by abrupt steering, so the roll control section h First, the damping coefficient changing means a is set so that the expansion side of the shock absorber b on the inner wheel side and the compression side of the shock absorber b on the outer wheel side have a high damping coefficient for a predetermined time. After a switching signal is output, each damping is performed for a predetermined time so that the compression side of the shock absorber b on the roll direction side and the extension side of the shock absorber b on the opposite side of the roll direction have high damping coefficients. A switching signal is output to the coefficient changing means a.

On the other hand, when there is a road surface input on the side opposite to the stroke of the shock absorber b during the roll control as described above, this road surface input is a predetermined value on the reverse stroke side of the shock absorber b. Is absorbed with a low damping coefficient of, and thus transmission to the vehicle body side is suppressed.

As described above, in the present invention, after the roll control is predictively performed based on the first turning direction, the roll control is performed based on the actual roll direction at the time when the roll actually occurs. As a result, the expansion / contraction speed and stroke on the stroke side of each shock absorber b corresponding to the actual roll direction are reliably suppressed with a high damping coefficient, which allows for rapid control without causing control delays or control timing deviations. It is possible to suppress the transient roll of the vehicle body based on various steering operations, and it is possible to reliably absorb the road surface input on the reverse stroke side with a predetermined low damping coefficient to ensure the ride comfort of the vehicle during roll control. .

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, the configuration of the embodiment will be described. FIG. 2 is a system block diagram of an embodiment of the present invention, in which SA is a damping force type shock absorber, 2 is a pulse motor, 3 is a sprung acceleration sensor, 4 is a steering sensor, 5 is a control unit. Shows.

A total of four shock absorbers SA are provided between each of the four wheels and the vehicle body.

The pulse motor 2 switches the damping coefficient position of the shock absorber SA, and changes the damping coefficient position of each shock absorber SA in multiple stages by step driving.

The sprung acceleration sensor 3 constitutes a vehicle behavior detecting means and a roll state detecting means. The sprung acceleration detecting means 3 is attached to a sprung vehicle body, detects a vertical acceleration on the sprung, and detects the sprung acceleration. The electric signal according to is output. The sprung acceleration sensor 3 is also provided for each shock absorber SA. Then, the sprung speed of each wheel portion is calculated based on the sprung acceleration, and the roll direction of the vehicle body is calculated based on the sprung speed deviation between the left wheel portion and the right wheel portion.

The steering sensor 4 constitutes a turning state detecting means, is provided in the steering wheel, and outputs an electric signal according to the turning angle. Then, the turning speed is calculated from the change in the turning angle.

The control unit 5 constitutes a control means, and in the damping coefficient control section thereof, in order to make the shock absorber SA the optimum damping coefficient based on the input signal from the sprung acceleration sensor 3, step In addition to outputting a control signal to the motor 2, the roll control unit performs control to set the damping coefficient of the shock absorber SA to a high value in order to suppress the roll. That is, the control unit 5 includes the interface circuit 5a and the CPU.
5b, a drive circuit 5c, and the interface circuit 5
Output signals from the vertical acceleration sensor 3 and the steering sensor 4 are input to a.

Next, FIG. 3 is a sectional view showing the structure of the shock absorber SA.
Is a cylinder 30, and the cylinder 30 is an upper chamber and a lower chamber B.
And a piston 31 defined by the outer cylinder 33 having a reservoir chamber C formed on the outer periphery of the cylinder 30, a base 34 defining the lower chamber B and the reservoir chamber C, and a piston rod 7 connected to the piston 31. Member 3 for guiding the sliding of
5, a suspension spring 36 interposed between the outer cylinder 33 and the vehicle body, and a bumper bar 37.

More specifically, as shown in FIG. 4, the shock absorber SA has a groove on the extension side inner side as a flow passage through which the fluid in the upper chamber A compressed in the extension stroke can flow to the lower chamber B side. From the position 11 of the expansion side damping valve 12, the inside and the outer peripheral portion of the expansion side damping valve 12 are opened to reach the lower chamber B through the expansion side first flow path D, the second port 13, the vertical groove 23, and the fourth port 14. Via the expansion side second flow path E, which opens the outer peripheral portion of the expansion side damping valve 12 from the position of the expansion side outer groove 15 to reach the lower chamber B, the second port 13, the vertical groove 23 and the fifth port 16. The extension-side check valve 17 is opened to reach the lower chamber B, and the bypass flow to the lower chamber B via the third port 18, the second lateral hole 25, and the hollow portion 19. There are four flow paths to the path G, and the fluid in the lower chamber B compressed in the pressure stroke flows to the upper chamber A side. As capacity flow path, the compression side damping valve 2
0 to open the pressure side first flow path H to the upper chamber A, and the pressure side check valve 22 to open to the upper chamber A via the hollow portion 19, the first lateral hole 24 and the first port 21. 2nd pressure side
Channel J, hollow 19, second lateral hole 25, and third port 1
3 with the bypass flow path G leading to the upper chamber A via 8
There are two channels.

The vertical groove 23 and the first and second lateral holes 2 are also provided.
The adjuster 6 in which 4, 25 are formed can switch the position of the damping coefficient in multiple stages among the three positions shown in FIGS. 5 to 7 based on the step rotation by the driving of the pulse motor 2. .

First, in the second position shown in FIG. 5 (the position shown in FIG. 8), the expansion side first flow path D, the compression side first flow path H and the compression side second flow path J can flow. As a result, as shown in FIG. 9, the extension side has a high damping coefficient (see FIG.
+ Xmax position), the pressure side of the reverse stroke has a predetermined low damping coefficient (-Xsoft position in FIG. 12).

Next, at the first position (position in FIG. 8) shown in FIG. 6, the four flow paths D,
E, F, G and all of the three flow paths H, J, G of the pressure stroke are allowed to flow, and as a result, as shown in FIG. 10, both the expansion side and the compression side have a predetermined low damping coefficient. (± Xsoft position in FIG. 12).

Next, at the third position shown in FIG. 7 (the position shown in FIG. 8), the extension side first to third flow paths D, E, F are formed.
Also, the pressure side first flow path H is allowed to flow, and as a result, as shown in FIG. 11, the pressure side has a high damping coefficient (see FIG. 12).
-Xmax position), the extension side of the reverse stroke has a predetermined low damping coefficient (+ Xsoft position in FIG. 12). The first and third positions can be switched in multiple stages according to the step rotation angle of the adjuster 6, and only the damping coefficient on the high damping coefficient side is proportional to the step rotation angle. Can be changed.

That is, in this shock absorber SA, when the adjuster 6 is rotated, the damping coefficient based on the rotation has characteristics as shown in FIG. It is configured so that it can be changed in multiple steps within the range of high damping coefficient. Moreover, as shown in FIG. 8, when the adjuster 6 is rotated counterclockwise from the position where the low damping coefficient (± Xsoft position in FIG. 12) is set on both the expansion side and the compression side, only the expansion side has a high damping coefficient. Change to the side and vice versa,
When the adjuster 6 is rotated clockwise, only the compression side changes to the high damping coefficient side.

Next, the operation flow of the damping coefficient position control in the control unit 5 will be described with reference to the flowchart shown in FIG.

First, at step 101, the sprung acceleration G of each wheel portion detected by the sprung acceleration sensor 3, the turning angle θ detected by the steering sensor 4, the sprung acceleration value on the left wheel side, and the right wheel. After reading the roll direction signals R of the vehicle obtained from the deviation from the side sprung acceleration value,
Go to step 102.

In step 102, the sprung acceleration G _R ,
After the sprung velocities V _R and V _L are calculated from G _L and the steered speed ω is calculated from the change in the steered angle θ, step 1
Go to 03.

Step 103 is the absolute value of the turning speed ± ω.
a step of determining whether or not | ω | exceeds an absolute value | a | of a predetermined threshold value ± a.
If the absolute value of a is less than | a | (NO), step 104
To the absolute value of the predetermined threshold value ± a | a |
If S), go to step 105.

Step 104 is a step for performing basic control of the damping coefficient. That is, in this basic control,
Sprung velocity ± V _R to the maximum damping coefficient ± Xhard position of FIG. 11, after being controlled switching the damping coefficient position in proportion respectively to ± V _L, completes one control flow.

The steps after step 105 are steps for performing roll control for suppressing the roll. In step 105, the timer T ₁ is started and then the process proceeds to step 106.

This step 106 is a step of determining whether or not the vehicle is turning to the right based on the turning direction determined from the direction of the turning speed ω. When the vehicle is turning to the right (YES),
In step 107, control is performed to switch the extension side of the right wheel and the compression side of the left wheel to the high damping coefficient position shown by the ± Xmax positions in FIG. 12, and if the steering wheel is in the right steering (NO) step 108. 12, the pressure side of the right wheel and the extension side of the left wheel are switched to the high damping coefficient position shown by the ± Xmax positions in FIG. 12, and then step 1 is performed.
Go to 09.

In this step 109, it is determined whether or not the time t ₁ measured by the timer T ₁ exceeds a predetermined time bsec, that is, the time until the rolling of the vehicle actually occurs due to the steering operation (about 0.1 second). If the determination step is less than the predetermined time bsec (NO), the process returns to step 106 to determine the turning direction of the vehicle, and if the predetermined time bsec or more (YES), the process proceeds to step 110 and the timer T ₂ After starting, the process proceeds to step 111.

This step 111 is a step of determining whether the rolling direction of the vehicle is the right rolling direction from the rolling direction signal R obtained from the deviation between the left wheel sprung speed V _R and the right wheel sprung speed V _L. When it is in the left roll direction (NO), the routine proceeds to step 112, where control is performed to switch the extension side of the right wheel and the compression side of the left wheel to the high damping coefficient position shown by ± Xmax positions in FIG. If it is in the roll direction (YES), the routine proceeds to step 113, where control is performed to switch the pressure side of the right wheel and the extension side of the left wheel to the high damping coefficient position shown by the ± Xmax positions in FIG. 12, and then the routine proceeds to step 114.

This step 114 is a step of judging whether or not the time t ₂ measured by the timer T ₂ has exceeded a predetermined time csec, that is, the time until the roll state of the vehicle generated by the steering operation converges. , Predetermined time csec
If it is less than (NO), the process returns to step 111 to determine the rolling direction of the vehicle, and the predetermined time csec or more (Y
When it becomes ES), this ends one control flow.

The control unit 5 repeats the above control flow.

Next, the operation of the embodiment will be described with reference to FIG. That is, FIG. 14 is a time chart for explaining the operation during traveling of the vehicle, and FIG. 14 (a) shows the right sprung speed V _R ,
The figure (b) is the right wheel damping coefficient switching position, the figure (c) is the left wheel sprung speed _VL , the figure (d) is the left wheel damping coefficient switching position, and the figure (e) is the steering speed ω, Figure (f) shows roll speed R
_V is shown respectively.

(A) At the time of basic control When the absolute value | ω | of the turning speed ± ω does not exceed the absolute value | a | of the predetermined threshold value ± a, the roll generated by turning is small, It is switched to normal basic control with the ± Xhard position as the maximum damping coefficient, and the stroke side of the shock absorber SA in the same direction as the sprung speed ± V at that time has a high damping coefficient proportional to the sprung speed ± V. Switching control of the damping coefficient position is performed. That is, a) As shown by c in FIG. 14, the absolute value of the turning speed ± ω |
ω | is less than the absolute value | a | of a predetermined threshold value ± a,
And when the direction of the sprung speed V is upward (+),
The second position (the direction of the sprung speed V at that time is the high damping coefficient position proportional to the sprung speed + V on the extension side, and the predetermined low damping coefficient (-Xsoft position) on the opposite compression side (Fig. 8 and the position of FIG. 9).

B) As shown by d in FIG. 14, the steering speed ±
The absolute value of ω | ω | is the absolute value of a predetermined threshold ± a | a |
And the direction of the sprung speed V is downward (-)
, The compression side, which is in the same direction as the direction of the sprung speed V at that time, has a high damping coefficient position proportional to the sprung speed −V, and the opposite expansion side has a predetermined low damping coefficient (+ Xsoft position). Third position (FIG. 8 and FIG. 1)
Switch to the (1 position) side.

Therefore, when the roll generation state is predicted by detecting the turning speed and there is no possibility that the roll will become violent,
That is, during straight running or during steady turning with a slow turning speed, the stroke direction side of the shock absorber SA, which is the same as the direction of the sprung speed ± V at that time, is controlled to an appropriate high damping coefficient proportional to the sprung speed ± V. By doing so, it is possible to appropriately suppress the vibration of the sprung body (vehicle body) to improve the steering stability and the riding comfort, and to reduce the shock absorber SA in the direction opposite to the direction of the sprung speed ± V at that time. By setting a predetermined low damping coefficient on the stroke side, it is possible to absorb road surface input in the direction opposite to the stroke direction during damping control, prevent transmission to the vehicle body, and further improve riding comfort.

(B) During roll control As shown in FIG. 14e, the absolute value of the turning speed ± ω | ω |
Is greater than the absolute value | a | of the predetermined threshold value ± a, the roll generated by abrupt steering becomes excessive, so roll control is started predictively based on the steering direction.

That is, when the steered direction at that time is the right steered direction, a roll is generated in the left direction, so that the extended side of the shock absorber SA on the right wheel side, which is the floating side, has a high damping coefficient ( + Xmax position), the opposite pressure side is switched to the second position (position in FIG. 8 and FIG. 9) where the predetermined low damping coefficient (−Xsoft position) is reached, and the shock on the left wheel side which is the sinking side. The absorber SA has a high damping coefficient (-Xmax position) on the compression side and a predetermined low damping coefficient (+ Xsoft) on the opposite expansion side.
The position is switched to the third position (positions in FIGS. 8 and 11).

This state is maintained for a predetermined time bsec until the roll is generated by the steering operation, and after that time, roll control is performed based on the actual roll direction.

That is, as shown in FIG. 14f, when the roll direction at that time is the right roll direction, the compression side of the right wheel side shock absorber SA, which is the depression side, has a high damping coefficient (-Xmax position). ), The opposite extension side is switched to the third position (position in FIG. 8 and FIG. 11) where a predetermined low damping coefficient (+ Xsoft position) is obtained, and in the shock absorber SA on the left wheel side, which is the floating side. The second position (FIG. 8 and FIG. 9) in which the extension side has a high damping coefficient (+ Xmax position) and the opposite compression side has a predetermined low damping coefficient (-Xsoft position).
Position).

After that, as shown in g of FIG.
When the roll direction changes to the left roll direction, the shock absorber S on the right wheel side, which is the floating side, is reversed, contrary to the previous situation.
In A, the extension side has a high damping coefficient (+ Xmax position)
Then, the opposite pressure side is switched to the second position (position in FIG. 8 and FIG. 9) where a predetermined low damping coefficient (−Xsoft position) is obtained, and in the left wheel side shock absorber SA which is the depression side. The compression side has a high damping coefficient (-Xmax position), and the opposite expansion side has a predetermined low damping coefficient (+ Xsoft position), which is switched to a third position (positions in FIGS. 8 and 11).

The roll control based on the roll direction is continued for a predetermined time csec until the roll by the turning steering is converged.

As described above, when the initial turning speed is high, first, the roll control is performed predictively based on the first turning direction, and then when the roll actually occurs, it is based on the actual rolling direction. By performing the roll control by means of the roll control, the expansion / contraction speed and stroke on the stroke side of each shock absorber SA corresponding to each roll direction can be reliably suppressed, and thereby control delay and control timing deviation can be prevented. The feature is that it is possible to suppress a transient roll of the vehicle body due to a sudden steering operation.

Further, the stroke side of the shock absorber SA in the direction opposite to the direction of the sprung speed ± V at that time is set as a predetermined low damping coefficient to surely absorb the road surface input in the direction opposite to the stroke direction. The feature is that the ride comfort can be secured during roll control.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific structure is not limited to this embodiment, and even if there are design changes and the like within the scope not departing from the gist of the present invention. Included in the present invention.

For example, in the embodiment, the case where the turning speed calculated by the turning angle is used as the detection value detected by the turning state detecting means is shown, but the threshold value control using the turning angle is performed. You may do it.

In the embodiment, the sprung acceleration sensor is used as the roll state detecting means, but the roll state can be detected by an acceleration sensor for detecting the widthwise acceleration of the vehicle.

Further, in the embodiment, in the basic control of the damping coefficient, the case where the damping coefficient is proportionally controlled according to the sprung speed is shown, but the factor relating to the vehicle behavior which is the basis of the damping coefficient control is arbitrary. Also, as the control method, control by a combination of a plurality of factors and threshold control can be performed.

[0051]

As described above, in the vehicle suspension system of the present invention, when one of the extension side and the compression side stroke side is controlled to the high damping coefficient side, the reverse stroke side has a low damping coefficient. A shock absorber having damping coefficient changing means, and a shock absorber which is on the inner wheel side in the turning direction for a predetermined time when the detection value detected by the turning state detecting means is equal to or more than a predetermined threshold value. A switching signal is output to each damping coefficient changing means so that the compression side of the shock absorber, which is the extension side and the outer ring side, has a high damping coefficient, and is detected by the roll state detecting means until a predetermined time elapses thereafter. The damping coefficient changing means so that the expansion side of the shock absorber on the roll direction side and the compression side of the shock absorber on the opposite side of the roll direction have high damping coefficients based on the rolling direction. By adopting a configuration that includes a roll control unit that outputs a switching signal, the expansion / contraction speed and stroke on the stroke side of each shock absorber that corresponds to the actual roll direction can be reliably suppressed, which allows control delay and control timing. It is possible to suppress the transient roll of the vehicle body due to a sudden steering operation without causing the deviation of the vehicle, and to reliably absorb the road surface input on the reverse stroke side with a predetermined low damping coefficient to control the vehicle during roll control. It is possible to obtain the effect that the ride comfort of the vehicle can be secured.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a vehicle suspension device of the present invention.

FIG. 2 is a system block diagram showing a vehicle suspension device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a shock absorber applied to the apparatus of the embodiment.

FIG. 4 is an enlarged sectional view showing a main part of the shock absorber.

5 is a sectional view showing a state of a second position, (a) is a sectional view taken along the line KK of FIG. 4, (b) is a sectional view taken along the line LL of FIG. 4, (c).
FIG. 6 is a sectional view taken along line N-N of FIG. 4.

6 is a sectional view showing a state of the first position, (a) is a sectional view taken along the line KK of FIG. 4, (b) is a sectional view taken along the line LL of FIG. 4, (c).
FIG. 6 is a sectional view taken along line N-N of FIG. 4.

7 is a sectional view showing a state of a third position, (a) is a sectional view taken along the line KK of FIG. 4, (b) is a sectional view taken along the line LL of FIG. 4, (c).
FIG. 6 is a sectional view taken along line N-N of FIG. 4.

FIG. 8 is a diagram showing a damping coefficient switching characteristic of the shock absorber.

FIG. 9 is a characteristic diagram of damping coefficient with respect to piston speed in the second position.

FIG. 10 is a characteristic diagram of damping coefficient with respect to piston speed in the first position.

FIG. 11 is a characteristic diagram of damping coefficient with respect to piston speed in the third position.

FIG. 12 is a variable characteristic diagram of the damping coefficient with respect to the piston speed of the embodiment apparatus.

FIG. 13 is a flowchart showing the operation flow of the control unit of the embodiment apparatus.

FIG. 14 is a time chart for explaining the operation of the embodiment apparatus when the vehicle is traveling.

[Explanation of symbols]

 a damping coefficient changing means b shock absorber c vehicle behavior detecting means d steering state detecting means e roll state detecting means f damping coefficient control section g control means h roll control section

[Procedure amendment]

[Submission date] April 20, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (1)

[Claims] 1. A damping coefficient change of a structure which is provided between a vehicle body and each wheel and which has a low damping coefficient on the reverse stroke side when one of the extension side and the compression side stroke side is controlled to the high damping coefficient side. A shock absorber having means, a vehicle behavior detecting means for detecting a factor relating to vehicle behavior, a steering state detecting means for detecting a steering state of the vehicle, a roll state detecting means for detecting a roll state of the vehicle, and When the detected value detected by the turning state detecting means is less than the predetermined threshold value, the damping coefficient is adjusted so that each shock absorber is controlled to the optimum damping coefficient based on the detected value detected by the vehicle behavior detecting means. A control unit having a damping coefficient control unit that outputs a switching signal to the changing unit, and a predetermined time when the detection value provided by the control unit and detected by the steering state detection unit is equal to or greater than a predetermined threshold value. Only that A switching signal is output to each damping coefficient changing means so that the extension side of the shock absorber on the inner wheel side with respect to the rudder direction and the compression side of the shock absorber on the outer wheel side each have a high damping coefficient, and then a predetermined time elapses. Up to the above, each damping coefficient is changed so that the compression direction of the shock absorber on the roll direction side and the expansion side of the shock absorber on the opposite side of the roll direction have high damping coefficients based on the roll direction detected by the roll state detection means. And a roll control unit that outputs a switching signal to the means.