JP3121925B2 - Vehicle suspension system - Google Patents

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 optimally controlling a damping characteristic of a shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension device for controlling damping characteristics of a shock absorber, for example, Japanese Unexamined Patent Publication No.
One described in Japanese Patent No. 184114 is known.

This conventional vehicle suspension device controls the damping characteristic of a shock absorber in accordance with the relative displacement between a sprung and unsprung state, and when the steering angular velocity exceeds a predetermined threshold value, This is provided with a damping characteristic control means for performing roll control by switching the damping characteristic to the hard characteristic side.

[0004]

However, in the above-described conventional device, the above-described configuration has the above-described configuration. Therefore, when the vehicle is driven on a bad road during roll control, the road surface input is sprung by a hard damping force. This causes a problem that the ride comfort of the vehicle is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. It is therefore an object of the present invention to suppress roll due to abrupt steering and to prevent deterioration of the riding comfort of a vehicle due to a protruding road surface input during a steering operation. It is an object of the present invention to provide a vehicle suspension device capable of performing the following.

[0006]

In order to achieve the above object, a vehicle suspension system according to the first aspect of the present invention, as shown in the claim correspondence diagram of FIG. A shock absorber b which is interposed and whose damping characteristic can be changed by the damping characteristic changing means a; a sprung vertical speed detecting means c which detects a sprung vertical speed near a position where each shock absorber b is provided; A steering angular velocity detecting means d for detecting a steering angular velocity, and a damping characteristic of each shock absorber b, a pitch rate detected from a bounce rate based on a sprung vertical velocity and a sprung vertical velocity difference between the front and rear of the vehicle and a sprung vertical movement of the left and right of the vehicle. A control unit f having an attenuation characteristic control unit e for performing control based on a control signal obtained from the roll rate detected from the speed difference, and a control unit provided in the control unit f, wherein the steering angular velocity is A steering correction control unit g that increases the proportional constant of the roll rate until the predetermined time elapses after the predetermined threshold value is exceeded and thereafter drops below the predetermined threshold value. Configuration.

According to a second aspect of the present invention, in the vehicle suspension system, when the steering angular velocity exceeds a predetermined threshold value, the steering correction control unit decreases the steering angular velocity to a predetermined threshold value or less, and then decreases the predetermined value. Until the passage of time, the proportional constant of the roll rate is increased in accordance with the value of the maximum steering angular velocity during that time.

In the vehicle suspension system according to a third aspect of the present invention, in obtaining the control signal, a signal passed through a band-pass filter including a sprung resonance frequency of each of the front and rear wheels is used as a bounce rate, and a pitch rate is A signal passed through a band-pass filter including the pitch resonance frequency was used, and a signal passed through a band-pass filter including the roll resonance frequency was used as the roll rate.

[0009]

When the bounce, pitch and roll are detected by the sprung acceleration detecting means and the sprung speed detecting means, the damping characteristic control section obtains a control signal based on the bounce rate, the pitch rate and the roll rate. The damping characteristic of the shock absorber is controlled according to the control signal, whereby a sufficient control force can be obtained not only for bounce but also for pitch and roll.

Further, a steering operation is performed while the vehicle is running,
When the steering angular velocity exceeds a predetermined threshold value, a process of increasing the proportional constant of the roll rate is performed until a predetermined time elapses after the steering angular velocity falls below the predetermined threshold value. Thereby, the roll of the vehicle caused by the abrupt steering operation due to the increase in the damping characteristic is sufficiently suppressed.

During roll control, the proportional constant of the roll rate is increased, but the bounce rate changes in accordance with the sprung vertical speed at that time. Transmission to the sprung can be suppressed.

According to a second aspect of the present invention, the proportional constant of the roll rate is increased in accordance with the value of the maximum steering angular velocity while the steering angular velocity exceeds a predetermined threshold value. Thus, roll suppression control according to the degree of steering is performed.

Further, in the device according to the third aspect, even when the sprung resonance frequency, the pitch resonance frequency, and the roll resonance frequency are different, appropriate damping control can be performed.

[0014]

An embodiment of the present invention will be described with reference to the drawings. (First Embodiment) First, the configuration will be described. FIG.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing a configuration of a vehicle suspension system according to a first embodiment, in which four shock absorbers SA ₁ , SA ₂ , SA ₃ , and SA ₄ are provided between a vehicle body and four wheels. In the description, when these four are collectively referred to, and when the common configuration is described, they are simply indicated as SA.). And, on the vehicle body in the vicinity of each shock absorber SA,
A vertical acceleration sensor that detects vertical acceleration (hereinafter
An upper and lower G sensor 1 is provided. Further, the steering ST unit is provided with a steering sensor 2 for detecting a steering angle. At a position near the driver's seat, there is provided a control unit 4 that receives signals from the upper and lower G sensors 1 and outputs a drive control signal to the pulse motor 3 of each shock absorber SA.

FIG. 3 is a system block diagram showing the above configuration. The control unit 4 includes an interface circuit 4a, a CPU 4b, and a drive circuit 4c. , The steering angle signal from the steering sensor 2, and the vehicle speed signal from the vehicle speed sensor 5. In the interface circuit 4a, FIG.
5 is a set of five filter circuits each of the upper and lower G sensors 1.
It is provided for each. That is, the LPF 1 is a high frequency band (30 Hz or more) from signals sent from the upper and lower G sensors 1.
Is a low-pass filter circuit for removing the noise of FIG. LPF2 is a low-pass filter circuit for integrating a signal indicating acceleration that has passed through low-pass filter circuit LPF1 and converting the signal into a sprung vertical velocity. BPF1 is
A bounce component signal v (v ₁ , v ₂ , v ₃ , v ₄ is passed through a frequency range including the sprung resonance frequency, and ₁ , ₂ , ₃ , ₄
Correspond to the position of each shock absorber SA. The same applies to the following. ) Is a band-pass filter circuit. The BPF 2 allows the pitch component signal v ′ (v ₁ ′, v
₂ ′, v ₃ ′, v ₄ ′). The BPF 3 allows the roll component signal v ″ (v ₁ ), v
₂ ″, v ₃ ″, v ₄ ″). In this embodiment, the sprung resonance, the pitch resonance, and the roll resonance have different frequencies. If the resonance frequencies are similar, the bandpass filter may be only the BPF1.

FIG. 4 is a sectional view showing the structure of the shock absorber SA.
A is a cylinder 30, a piston 31 that defines the cylinder 30 in an upper chamber A and a lower chamber B, an outer cylinder 33 in which a reservoir chamber 32 is formed on the outer periphery of the cylinder 30, a lower chamber B and a reservoir chamber 32. Base 34 and piston 31
A guide member 35 for guiding the sliding of the piston rod 7 connected to the outer cylinder 33, a suspension spring 36 interposed between the outer cylinder 33 and the vehicle body, and a bump rubber 37.

FIG. 5 is an enlarged sectional view showing a portion of the piston 31. As shown in FIG. 5, the piston 31 has through holes 31a and 31b formed therein, and An expansion damping valve 12 and a compression damping valve 20 for opening and closing 31a and 31b, respectively, are provided. A stud 38 that penetrates the piston 31 is screwed and fixed to the bound stopper 41 screwed to the tip of the piston rod 7, and the stud 38 bypasses the through holes 31a and 31b. Communication for forming flow paths (extension-side second flow paths E, expansion-side third flow paths F, bypass flow paths G, and compression-side second flow paths J to be described later) that communicate the upper chamber A and the lower chamber B. A hole 39 is formed.
An adjuster 40 for changing the flow path cross-sectional area of the flow path is rotatably provided in 9. Also, stud 38
The communication hole 3 is formed on the outer periphery of the communication hole 3 in accordance with the direction of fluid flow.
An expansion-side check valve 17 and a compression-side check valve 22 that allow and shut off the flow on the flow path side formed by 9 are provided. Note that the adjuster 40 is provided with the pulse motor 3.
Is rotated through the control rod 70 (see FIG. 4). Also, studs 38
A first port 21, a second port 13, a third port 18, a fourth port 14, and a fifth port 16 are formed in this order from the top.

On the other hand, the adjuster 40 has a hollow portion 19, a first horizontal hole 24 and a second horizontal hole 25 communicating between the inside and the outside, and a vertical groove 23 formed in the outer peripheral portion. I have.

Therefore, between the upper chamber A and the lower chamber B, a through-hole 31 is formed as a flow path through which fluid can flow during the extension stroke.
b, the inside of the extension side damping valve 12 is opened to open the lower chamber B
, The second port 13, the vertical groove 23,
Via the second port 13, the vertical groove 23, and the fifth port 16 via the fourth port 14, the outer peripheral side of the extension side damping valve 12 is opened to open the outer peripheral side of the extension side damping valve 12 to reach the lower chamber B, Then, the extension side check valve 17 is opened to open the extension side third flow path F to the lower chamber B, and the bypass to the lower chamber B via the third port 18, the second horizontal hole 25, and the hollow portion 19. There are four flow paths G. In addition, as a flow path through which fluid can flow in the pressure stroke, the pressure side first valve that opens the pressure side damping valve 20 through the through hole 31a.
Channel H, hollow portion 19, first lateral hole 24, first port 21
, The pressure-side second flow path J that opens the pressure-side check valve 22 to reach the upper chamber A through the air passage, and the bypass flow that reaches the upper chamber A through the hollow portion 19, the second horizontal hole 25, and the third port 18. Road G
And three flow paths.

That is, the shock absorber SA is configured so that the damping characteristic can be changed in multiple steps by rotating the adjuster 40 with the characteristics shown in FIG. 6 on both the extension side and the compression side. That is, as shown in FIG. 7, a state where both the extension side and the compression side are soft (hereinafter, the soft area S
When the adjuster 40 is rotated in the counterclockwise direction from S), the damping characteristic can be changed in multiple stages only on the extension side, and the compression side becomes a region fixed to the low attenuation characteristic (hereinafter referred to as the extension side hard region HS). Conversely, when the adjuster 40 is rotated clockwise, the attenuation characteristic can be changed in multiple stages only on the compression side, and the expansion side becomes a region fixed to the low attenuation characteristic (hereinafter referred to as a compression side hard region SH). I have.

In FIG. 7, the KK section, the LL section, the MM section, and the NN section in FIG. 5 when the adjuster 40 is arranged at the position of, respectively. 8, 9 and 10 and the damping force characteristics at each position are shown in FIGS.

Next, the operation of the control unit 4 for controlling the driving of the pulse motor 3 will be described with reference to the flowchart of FIG. This control is performed separately for each shock absorber SA.

In step 101, the steering sensor 2
The operation angular velocity θ is obtained from the change rate of the steering angle detected by the above, and the vertical acceleration obtained from each of the vertical G sensors 1, 1, 1, 1 is calculated by the filter circuits LPF1, BPF1, BPF.
2, BPF3 and LPF2 to obtain a bounce component signal v, a pitch component signal v ', and a roll component signal v ". Based on the map shown in FIG. 18, each component signal v, v ′, v ″ proportional constant α (α
_f , α _r ), β (β _f , β _r ), and γ (γ _f , γ _r ). In addition, each component signal v, v ', v "
Is given as a positive value when the sprung vertical acceleration is in the upward direction, and as a negative value when the sprung vertical acceleration is in the downward direction. The steering angular velocity θ is the shock absorber S on the steering direction side.
A is a positive value because the vehicle is on the rising side (extending stroke side), and is negative because the shock absorber SA on the side opposite to the steering direction is on the sinking side (pressure stroke side) of the vehicle body. Given by value.

In step 102, the absolute value of the steering angular velocity |
is a step of determining whether or not θ | is equal to or greater than a predetermined threshold value θ _TH.
Then, the process proceeds to step 104.

In step 103, the absolute value of the steering angular velocity |
is a step of determining whether or not the predetermined time T has elapsed after θ | has fallen below the predetermined threshold value θ _TH . If NO, the flow proceeds to step 105;

In step 104, the proportional constant γ (γ _f , γ _r ) of the roll component signal v ″ is calculated as γ _f + γ _B , γ _r + γ _B
This is the step of switching to. Note that γ _B is a correction constant for increasing the value of the proportionality constant γ set in accordance with the vehicle speed in step 101, and this value is equal to the threshold θ
It is increased and changed according to the maximum value of the steering angular velocity while _{exceeding TH} .

Step 105 uses the following equation (1).
Each component signal v, v'v "and each proportional constant α, β, γ (γ
_This is a step of calculating control signals V (V ₁ , V ₂ , V ₃ , V ₄ ) for the position of each wheel based on _f , γ _r or γ _f + γ _B , γ _r + γ _B ).

[0028]

(Equation 1) Note that α _f , β _f , and γ _f are the respective proportional constants of the front wheels α _r , β _r , and γ _r are the respective proportional constants of the rear wheels. Also,
In each equation, the part bounded by the first α _f and α _r is the bounce rate, the part bounded by β _f and β _r is the pitch rate, and the part bounded by γ _f and γ _r is the roll Rate.

[0029] Step 106, the control signal V is a step equal to or larger than a predetermined threshold value [delta] _T, the process proceeds to step 107 in YES, a step 1 is NO
Proceed to 08.

In step 107, the shock absorber S
This is a step of controlling A to the extension-side hard area HS.

[0031] Step 108, the control signal V is determining whether a value between a predetermined threshold value [delta] _T and the threshold - [delta _C, the process proceeds to step 109 YES, a by NO Proceed to step 110.

In step 109, the shock absorber S
This is the step of controlling A to the soft area SS.

Step 110 is a step displayed for the sake of convenience.
When it is determined that O is the control signal V is less than a predetermined threshold value - [delta _C, in this case, the process proceeds to step 111.

Step 111 is a step S
This is a step of controlling A to the compression side hard area SH.

Next, the operation of the embodiment will be described with reference to the time chart of FIG. If the vertical sprung mass velocity is varied as shown in the control signal V in the figure, as shown in FIG, when the control signal V is a value between the predetermined threshold value [delta] _T, - [delta _C is shock Absorber SA in soft area S
Control to S.

When the control signal V becomes equal to or greater than the threshold value δ _{T, the} compression side is controlled to the expansion side hard region HS so that the compression side is fixed to a low attenuation characteristic, while the expansion side attenuation characteristic is made proportional to the control signal V. Change. At this time, the attenuation characteristic C is C = k ₁ · V
Is controlled so that

When the control signal V becomes equal to or smaller than the threshold value -δ _{C, the} compression side is controlled to the compression side hard area SH to fix the expansion side to low attenuation characteristics, while making the compression side attenuation characteristics proportional to the control signal V. Change. Also at this time, the attenuation characteristic C is C = k ₂
・ V is controlled to be V. Note that the k ₁ is the extension side of the proportionality constant, k ₂ is a proportionality constant of the pressure side.

In the time chart of FIG.
The area a is a state in which the control signal V based on the sprung vertical speed is reversed from a negative value (downward) to a positive value (upward), but at this time, the relative speed is still a negative value (the shock absorber SA has a negative value). Since the stroke is a pressure stroke side), at this time, the shock absorber SA is controlled to the extension side hard region HS based on the direction of the control signal V.
Therefore, in this area, the shock absorber SA at that time is
The pressure stroke side, which is the stroke of, has soft characteristics.

In the region b, the control signal V based on the sprung vertical speed remains a positive value (upward), and the relative speed changes from a negative value to a positive value (the stroke of the shock absorber SA is on the extension stroke side). At this time, the shock absorber SA is controlled to the extension-side hard area HS based on the direction of the control signal V, and the stroke of the shock absorber is also the extension stroke. In this region, the extension stroke, which is the stroke of the shock absorber SA at that time, has a hard characteristic proportional to the value of the control signal V.

The area c is a state where the control signal V based on the sprung vertical speed is reversed from a positive value (upward) to a negative value (downward), but at this time, the relative speed is still a positive value. (The stroke of the shock absorber SA is on the extension stroke side.) At this time, the shock absorber SA is controlled to the compression-side hard region SH based on the direction of the control signal V. Then, the extension stroke side, which is the stroke of the shock absorber SA at that time, has the soft characteristic.

In the area d, the control signal V based on the sprung vertical speed remains a negative value (downward), and the relative speed changes from a positive value to a negative value (the stroke of the shock absorber SA is on the extension stroke side). At this time, the shock absorber SA is controlled to the compression-side hard region SH based on the direction of the control signal V, and the stroke of the shock absorber is also the compression stroke. Therefore, in this region, The pressure stroke side, which is the stroke of the shock absorber SA at that time, has hardware characteristics proportional to the value of the control signal V.

As described above, in this embodiment, when the sprung vertical speed and the relative speed between the sprung and unsprung have the same sign (region b, region d), the shock absorber S at that time is used.
A damping characteristic control based on the skyhook theory, in which the stroke side of A is controlled to a hard characteristic, and when the sign is different (regions a and c), the stroke side of the shock absorber SA at that time is controlled to a soft characteristic. The same control will be performed without detecting the relative speed between sprung and unsprung. Further, in this embodiment, when shifting from the area a to the area b and from the area c to the area d, the switching of the damping characteristic is performed without driving the pulse motor 3.

Next, the operation of the control unit 4 when the vehicle travels straight and when it is steered will be described with reference to the time chart of FIG. (A) Straight running When the vehicle is in a straight running state (when the steering angular velocity | θ | is within the range of a predetermined threshold value θ _TH ), no large roll is generated, so the steering control is turned off. In this state, the control signal V is obtained based on the bounce component signal v, the pitch component signal v ', the roll component signal v ", and the proportional constants α, β, and γ set according to the vehicle speed. In addition, a sufficient control force can be generated for a pitch or a roll generated during straight running.

(B) At the time of steering If a sudden steering operation is performed during the running of the vehicle, the absolute value | θ | of the steering angular velocity becomes equal to or more than the predetermined threshold value _θTH , so that the steering control is turned ON. Then, a predetermined threshold θ
Until the predetermined time T elapses after the temperature has dropped below _TH, a process of increasing the roll gain (proportional constant of the roll component signal) according to the value of the maximum steering angular velocity during that time is performed. That is, the bounce component signal v, the pitch component signal v ′, the roll component signal v ″, the proportional constants α and β set according to the vehicle speed, and the roll component signal v ″ increased according to the maximum value of the steering angular velocity. Constants γ _f + γ _B , γ _r +
The control signal V is obtained based on γ _B.

Therefore, the roll of the vehicle caused by the sudden steering operation can be sufficiently suppressed according to the magnitude of the steering angular velocity at that time.

(C) When the vehicle climbs over a protrusion during the steering operation As described above, during a rapid steering, the roll rate becomes larger than that during the straight running, but the damping characteristic is proportional to the sprung vertical speed at that time. Control is basically performed, damping characteristic control is performed in accordance with the input condition from the road surface, and therefore, the ride comfort of the vehicle can be reduced even with respect to the projecting road surface input during steering control. Can be secured.

As described above, in this embodiment, the following effects can be obtained. When traveling straight, sufficient control force can be generated not only for bounces but also for rolls and pitches, so that it is possible to provide a vehicle suspension system having excellent ride comfort and steering stability.

[0048] By the steering control, the roll of the vehicle caused by the abrupt steering operation can be suppressed according to the degree of steering at that time. The damping characteristic control according to the speed change is performed, and the riding comfort of the vehicle can be secured.

Since the frequency of switching of the damping characteristic is reduced as compared with the damping characteristic control based on the conventional skyhook theory, the control responsiveness can be improved and the durability of the pulse motor 3 can be improved.

In obtaining the bounce rate, pitch rate, and roll rate, different constants α,
Since β and γ are used, in the vehicle, even if the sprung resonance frequency, the pitch resonance frequency, and the roll resonance frequency are different from each other, each rate can be accurately detected based on the sprung vertical speed.

Next, other embodiments will be described. In describing these embodiments, only differences from the first embodiment will be described. In addition, the first reference
The same reference numerals as those in the embodiments indicate the same objects.

(Second Embodiment) The second embodiment is different from the first embodiment in that a part of the control unit 4 is different from that of the first embodiment. Use the formula.

[0053]

(Equation 2)

(Equation 3) That is, in the second embodiment, the bounce rate is independently obtained based on the sprung vertical velocity of each wheel, so that control can be performed with the bounce component emphasized.

Although the embodiment has been described above, the specific configuration is not limited to this embodiment, and any change in the design without departing from the gist of the present invention is included in the present invention.

For example, in the embodiment, when variably controlling the damping characteristic of one stroke side on the extension side or the compression side, a shock absorber having a structure in which the reverse stroke side is maintained at a predetermined low damping characteristic is used. Control using a shock absorber having a structure in which the damping characteristics of the pressure side and the compression side simultaneously change can be performed.

[0056]

As described above, in the vehicle suspension system according to the present invention, the damping characteristics of each shock absorber are controlled by the damping characteristics control means to determine the difference between the bounce rate based on the sprung vertical speed and the sprung vertical speed between the front and rear of the vehicle. Control based on the control signal obtained from the pitch rate detected from the vehicle and the roll rate detected from the difference between the sprung vertical speed of the vehicle left and right, not only for bounce, but also for pitch and roll during straight running A sufficient control force can be obtained, and thereby, the effect that the riding comfort and the steering stability can be improved can be obtained.

When the steering angular velocity exceeds a predetermined threshold value, the proportional constant of the roll rate is increased until a predetermined time elapses after the steering angular velocity falls below the predetermined threshold value. By providing a steering correction control unit, the roll of the vehicle due to a sudden steering operation can be sufficiently suppressed, and the damping characteristic control based on the sprung vertical speed can be performed even for a protruding input during the steering operation. Working can ensure the ride comfort of the vehicle.

According to the second aspect of the present invention, the degree of steering is increased by increasing the proportional constant of the roll rate in accordance with the value of the maximum steering angular velocity while the steering angular velocity exceeds a predetermined threshold value. Can be performed in accordance with the roll control.

Further, in the device according to the third aspect, even when the sprung resonance frequency, the pitch resonance frequency, and the roll resonance frequency are different, appropriate damping control can be performed.

[Brief description of the drawings]

FIG. 1 is a conceptual view of a claim showing a vehicle suspension system of the present invention.

FIG. 2 is a configuration explanatory view showing a vehicle suspension system according to a first embodiment of the present invention.

FIG. 3 is a system block diagram showing a vehicle suspension system according to a first embodiment.

FIG. 4 is a sectional view showing a shock absorber applied to the first embodiment device.

FIG. 5 is an enlarged sectional view showing a main part of the shock absorber.

FIG. 6 is a damping force characteristic diagram corresponding to a piston speed of the shock absorber.

FIG. 7 is a characteristic diagram of a damping characteristic corresponding to a step position of a pulse motor of the shock absorber.

FIG. 8 is a perspective view of the shock absorber shown in FIG.
It is -K sectional drawing.

FIG. 9 is a perspective view of the shock absorber shown in FIG.
It is an L sectional view and MM sectional view.

FIG. 10 is a sectional view taken along line NN of FIG. 5 showing a main part of the shock absorber.

FIG. 11 is a damping force characteristic diagram when the shock absorber is on the extension side hard.

FIG. 12 is a damping force characteristic diagram of the shock absorber in a soft state on an extension side and a compression side.

FIG. 13 is a damping force characteristic diagram of the shock absorber in a pressure-side hard state.

FIG. 14 is a block diagram showing a main part of a control unit of the first embodiment device.

FIG. 15 is a flowchart showing a control operation of a control unit in the first embodiment.

FIG. 16 is a time chart showing the operation of damping characteristic control in the control unit of the first embodiment.

FIG. 17 is a time chart showing the operation of control during steering of the control unit in the device of the first embodiment.

FIG. 18 is a map showing a proportional constant in the device of the first embodiment.

[Explanation of symbols]

 a damping characteristic changing means b shock absorber c sprung vertical speed detecting means d steering angular velocity detecting means e damping characteristic control part f control means g steering correction control part

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60G 17/015 B60G 17/08

Claims (3)

(57) [Claims] 1. A shock absorber interposed between a vehicle body side and each wheel side and capable of changing damping characteristics by damping characteristic changing means, and detecting a sprung vertical speed near a position where each shock absorber is provided. A sprung vertical velocity detecting means, a steering angular velocity detecting means for detecting a steering angular velocity of the vehicle, and a damping characteristic of each shock absorber, a pitch detected from a bounce rate based on the sprung vertical velocity and a sprung vertical velocity difference between front and rear of the vehicle body. Control means having a damping characteristic control unit for controlling based on a control signal obtained from the rate and a roll rate detected from a difference between a sprung vertical velocity of the left and right of the vehicle body, and a steering threshold for controlling a steering angular velocity by a predetermined threshold When the value exceeds the threshold value, the proportional constant of the roll rate is increased until the predetermined time elapses after the value falls below the predetermined threshold value. Vehicle suspension system characterized in that it comprises a steering correction controller that, the. 2. When the steering angular velocity exceeds a predetermined threshold value, the steering correction control unit may reduce the steering angular velocity below the predetermined threshold value until a predetermined time elapses. 2. The vehicle suspension according to claim 1, wherein the proportional constant of the roll rate is increased in accordance with the value of the maximum steering angular velocity of the vehicle. 3. The control signal is obtained by using a signal passed through a band-pass filter including a sprung resonance frequency of each of the front and rear wheels as a bounce rate, and using a band-pass filter including a pitch resonance frequency as a pitch rate. 3. The vehicle suspension according to claim 1, wherein a signal passed through a band-pass filter including a roll resonance frequency is used as the roll rate.