JP3194451B2 - 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.
What is described in 163011 is known.

This conventional vehicle suspension detects a sprung vertical speed and a sprung / unsprung relative speed, and when the two direction discrimination codes are the same, the damping characteristic is made hard and the two are different signs. In the case of, the damping characteristic control based on the Skyhook theory of softening the damping characteristic is performed independently for the four wheels.

[0004] In such a system, the attenuation characteristic F when hardened is generally obtained based on the following equation.

F = α × Vn (α: control gain, Vn: sprung vertical velocity)

[0006]

However, since the above-described conventional apparatus has the above-described configuration, it is difficult to set a control gain suitable for vibration suppression control of vehicle behavior occurring during straight running. However, during a steering operation in which a moment of inertia acts on the vehicle, there is a problem that sufficient vibration suppression cannot be obtained and an understeering state occurs, thereby deteriorating the steering stability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to improve the steering stability of a vehicle during a steering operation without deteriorating the riding comfort of the vehicle when traveling straight. It is an object of the present invention to provide a vehicle suspension device capable of performing the following.

[0008]

In order to achieve the above object, a vehicle suspension system according to the present invention is interposed between a vehicle body side and each wheel side as shown in FIG. A shock absorber b whose damping characteristic can be changed by a characteristic changing means a, and a sprung vertical speed for detecting a sprung vertical speed
Degree detecting means c , a bounce rate based on the sprung vertical speed detected by the sprung vertical speed detecting means c,
Pitch rate and left and right springs detected from difference in vertical speed
Calculated from the roll rate detected from the vertical speed difference
Control means e having an attenuation characteristic control section d for controlling the attenuation characteristic of each of said shock absorbers b based on a control signal
And yaw rate detecting means f for detecting the yaw rate of the vehicle
And a yaw rate detecting means f provided in the control means e.
When the direction of the yaw rate and the direction of the rate of change of the yaw rate detected in the above are the same direction, the control gain of the rear wheel side damping characteristic is set higher than the control gain of the front wheel side damping characteristic, and the direction is opposite. In some cases, the control device includes a gain correction control unit g that sets the control gain of the rear wheel-side damping characteristic lower than the control gain of the front wheel-side damping characteristic.

Further, in the vehicle suspension device according to the second aspect,
The yaw rate detecting means comprises a lateral acceleration detecting means for detecting a lateral acceleration of the vehicle.

Further, in the vehicle suspension device according to the third aspect,
The yaw rate detecting means is constituted by a steering angular velocity detecting means for detecting a steering angular velocity.

[0011]

[0012]

According to the present invention , the sprung vertical speed is detected as described above.
By means of bounce, pitch and roll detected
In addition, the bounce rate and pitch rate
Control signal based on the
Control the damping characteristics of the shock absorber according to the signal
This allows not only the bounce, but also the pitch,
Control of the vehicle, and
The ground and steering stability can be improved .

Further, when the vehicle starts turning from a straight running state by a steering operation, the direction of the yaw rate and the direction of the rate of change of the yaw rate become the same direction. The control gain is set to be higher than the control gain on the front wheel side, whereby the front load of the vehicle increases and the vehicle enters an over-steering state, so that turning performance during steering can be improved.

Further, when the vehicle is changing its direction from the steady turning state to the straight running direction due to the turning back of the steering, the direction of the yaw rate and the direction of the rate of change of the yaw rate are opposite to each other. The control gain on the rear wheel side is set lower than the control gain on the front wheel side, whereby the front load of the vehicle is reduced and the vehicle enters an under-steering state, so that the convergence of the vehicle can be improved. .

[0015]

[0016]

An embodiment of the present invention will be described with reference to the drawings. First, the configuration will be described. FIG. 2 is a configuration explanatory view showing the vehicle suspension device of the embodiment, and is interposed between the vehicle body and four wheels, and is provided with four shock absorbers SA ₁ and SA.
₂ , SA ₃ , and SA ₄ (in the description of the shock absorber, when these four are collectively referred to, and when the common configuration is described, they are simply indicated as SA). A vertical acceleration sensor (hereinafter referred to as a vertical G sensor) for detecting a vertical acceleration is provided on the vehicle body near each shock absorber SA.
The vehicle body near the center of gravity of the vehicle is provided with a lateral acceleration sensor 2 for detecting the lateral acceleration of the vehicle.
And a signal from the lateral acceleration sensor 2 to output 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. a vertical acceleration G _T signal, the lateral acceleration G _Y signal from the lateral acceleration sensor 2, a vehicle speed signal from a vehicle speed sensor 5 are input. The interface circuit 4
14A, a set of five filter circuits as shown in FIG. 14A is provided for each of the upper and lower G sensors 1.
A set of two filter circuits is provided as shown in (b). That is, in FIG. 14A, the LPF 1 is a high frequency band (30 Hz) from the signals sent from the upper and lower G sensors 1.
LPF2 is a low-pass filter circuit for integrating a signal indicating acceleration that has passed through the low-pass filter circuit LPF1 and converting the signal into a sprung vertical velocity. Also, B
The PF1 passes the frequency range including the sprung resonance frequency and passes through the bounce component signals v (v1, _v2 , _v3 , _v4 , where the numbers ₁ , ₂ , ₃ , ₄ are at the positions of the respective shock absorbers SA. The BPF 2 passes the frequency range including the pitch resonance frequency to pass the pitch component signal v ′.
(V ₁ ′, v ₂ ′, v ₃ ′, v ₄ ′), and the BPF 3 allows the roll component signal v ″ (v
_{1 ", v 2", v} 3 ", v 4") is a band-pass filter circuit forming the. Further, in FIG.
PF is a high-pass filter circuit for differentiating the lateral acceleration _GY signal sent from the lateral acceleration sensor 2 and converting the signal into a lateral acceleration change rate (jerk) R. LPF3 is a signal passed through the high-pass filter circuit HPF. This is a low-pass filter circuit for removing high-frequency noise from the signal. Incidentally, in the present embodiment, the case where the sprung resonance, the pitch resonance, and the roll resonance have different frequencies is taken as an example. However, when these resonance frequencies are close to each other, only the BPF1 may be used as the bandpass filter.

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 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 such that the damping characteristic can be changed in multiple stages 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 upper and lower G sensors 1,
The sprung mass vertical accelerations G _T obtained from 1,1,1 reads in respectively the step of reading the lateral acceleration G _Y obtained from the lateral acceleration sensor 2.

In step 102, the sprung vertical acceleration G _T
Signals are output from the respective filter circuits LPF1 and LPF1 shown in FIG.
PF1, BPF2, BPF3, and LPF2 are processed to obtain a bounce component signal v, a pitch component signal v ′, and a roll component signal v ″ of the sprung vertical velocity, and the lateral acceleration G _Y obtained from the lateral acceleration sensor 2 is shown in FIG. This is the step of obtaining the lateral acceleration change rate R by processing with both filter circuits HFP and LPF3 shown in FIG.

In step 103, it is determined whether or not the rate of change R of the lateral acceleration is within a predetermined small threshold value (near zero) (-Rx <
R <+ Rx). If YES (within the range of the minute threshold value), the routine proceeds to step 104, where the front wheel-side control gain K _f and the rear wheel-side control gain K _r are set to standard values. After setting k ₀ , the process proceeds to step 108, and if NO (outside the minute threshold range), step 10
Go to 5.

Step 105 is to determine whether the direction of the lateral acceleration G _{Y and} the direction of the rate of change R of the lateral acceleration are the same (G _Y × R>
0), and if YES (same direction), the process proceeds to step 106, where the front-wheel-side control gain K is set.
_f is set to a value k _L lower than the standard value k ₀ , and the control gain K _r on the rear wheel side is set to a value k _H higher than the standard value k _0. Direction), the routine proceeds to step 107, where the front-wheel-side control gain K
After setting _f to a value k _H higher than the standard value k ₀ and setting the rear wheel side control gain K _r to a value k _L lower than the standard value k ₀ , the routine proceeds to step 108.

Step 108 uses the following equation (1).
The control signals V (V ₁ , V ₂ , V ₃ , V ₃₎ of the position of each wheel are determined based on the component signals v, v′v ″, the proportional constants α, β, γ, and the control gains K _f , K _{r. 4} ) The proportional constants α, β, and γ are continuously switched according to the vehicle speed.

Front right wheel V ₁ = K _f (α _f · v ₁ + β _f (v ₁ '-v ₃ ') + γ _f
(v ₁ "-v ₂ ")) Front wheel left V ₂ = K _f (α _f · v ₂ + β _f (v ₂ '-v ₄ ') + γ _f
(v ₂ "-v ₁ ")) Rear wheel right V ₃ = K _r (α _r · v ₃ + β _r (v ₃ '-v ₁ ') + γ _r
(v ₃ "-v ₄ ")) Rear wheel left V ₄ = K _r (α _r · v ₄ + β _r (v ₄ '-v ₂ ') + γ _r
(v ₄ "-v ₃ ")) Note that α _f , β _f , and γ _f are proportional constants on the front wheel side α _r , β _r , and γ _r are respective proportional constants on the rear wheel side. In each of the equations, 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.

[0030] 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 expansion side hard region HS and setting the expansion side attenuation characteristic to a value proportional to the control signal V.

[0032] Step 108 is a step of determining whether a value between the control signal V is 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,
This is a step of controlling the shock absorber SA to the compression side hard region SH and setting the compression characteristic on the compression side to a value proportional to the control signal V.

Next, the control operation of the control unit 4 will be described with reference to the time chart of FIG.

When the control signal V based on the sprung vertical velocity changes as shown in FIG. 5, when the control signal V is a value between the predetermined thresholds δ _T and −δ _C , the shock absorber SA is turned off. Control to the soft area SS.

When the control signal V exceeds the threshold value δ _{T, the} compression side is controlled to the expansion side hard region HS to fix the compression side to a low attenuation characteristic, while making the expansion side attenuation characteristic proportional to the control signal V. Change. At this time, the attenuation characteristic F is given by F = θ _T · V
It is controlled so that Note that θ _T is a proportional constant on the extension side.

When the control signal V becomes equal to or less than the threshold value -δ _{C, the} compression side is controlled to the compression side hard area SH to fix the extension side to the low attenuation characteristic, while making the compression side attenuation characteristic proportional to the control signal V. Change. Also at this time, the attenuation characteristic F is given by F = θ _C
・ V is controlled to be V. Θ _C is a proportional constant on 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 a, the shock absorber S at that time is
The pressure stroke side, which is the stroke of A, 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 b, the extension stroke side, 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.

Area c is a state in which the control signal V based on the sprung vertical velocity is reversed from a positive value (upward) to a negative value (downward). At this time, the relative velocity 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. In c, the softening characteristic is on the extension stroke side which is the stroke of the shock absorber SA at that time.

In a region 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. Then, the pressure stroke side, 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.

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 gain correction control section in the control unit 4 will be described with reference to the time chart of FIG.

(A) At the start of turning At the time when the vehicle starts turning from a straight running state by the steering operation, the direction of the lateral acceleration G and the direction of the rate of change R of the lateral acceleration are the same as shown in FIG. At this time, the control gain K _r (k _H ) on the rear wheel side is set higher than the control gain K _f (k _L ) on the front wheel side, thereby increasing the front load of the vehicle. Then, an oversteering state is set.

Therefore, the turning performance at the time of steering can be improved.

(B) Straight running and steady turning When the vehicle is in a straight running state or in a steady turning state, the lateral acceleration change rate R is close to 0 as shown in or in FIG. At this time, the control gains K _f and K _r for the front and rear wheels are set to the standard value k ₀ , thereby improving the riding comfort of the vehicle.

(C) At the time of turning back the steering When the vehicle is changing its direction from the steady turning state to the straight running direction, as shown in FIG. 17, the direction of the lateral acceleration G and the direction of the lateral acceleration change rate R are as shown in FIG. Is opposite, the control gain K _r (k _L ) on the rear wheel side is set lower than the control gain K _f (k _H ) on the front wheel side at this time. Is reduced, and an under steering state is set.

Therefore, the convergence of the vehicle can be improved.

As described above, in this embodiment, the following effects can be obtained. Without deteriorating the riding comfort of the vehicle during straight running or steady turning, the vehicle's damping performance at the start of steering operation and at the time of turning back of steering can be enhanced, and the steering stability of the vehicle can be improved.

Since a sufficient control force can be generated not only for the bounce but also for the roll and the pitch, it is possible to provide a vehicle suspension device excellent in ride comfort and steering stability.

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

Since the damping characteristic control based on the skyhook theory can be performed only by detecting the sprung vertical speed as the vehicle behavior, the cost can be reduced.

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.

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

For example, in the embodiment, the attenuation characteristic F is made to be proportional to the control signal V based on predetermined proportional constants θ _T and θ _C.
Although the control is performed so that F = θ _T · V and F = θ _C · V, it is also proportional to the value of the rate of change R of the lateral acceleration, and F = θ _T · R · V, F = It is also possible to control so as to be θ _C · R · V.

Further, the high value k _H and the low value k _L of the rear wheel side gains K _f and K _{r in} the embodiment are changed by the change rate R of the lateral acceleration as shown in the map of FIG. It can also be variably set based on the correction function to be performed.

[0058]

Further, in the embodiment, the bounce rate is independently obtained based on the sprung vertical speed at each wheel position. However, the bounce rate is calculated based on the average value of the sprung vertical speed at each wheel position. May be obtained.

Further, in the embodiment, the upper and lower G sensors are independently provided at the respective wheel positions. However, in order to control the bounce and the pitch, it is only necessary to provide a pair of sensors at least on the front wheel side and the rear wheel side. However, only one bounce control is required to perform the bounce suppression control.

Further, in the embodiment, when the damping characteristic on one of the stroke side on the extension side and the compression side is variably controlled, 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.

Further, in this embodiment, a lateral acceleration sensor for detecting the lateral acceleration of the vehicle is used as the yaw rate detecting means, and the control gain correction control based on the relative direction discrimination between the lateral acceleration and the change rate of the lateral acceleration is performed. Although the description has been given of an example in which the control is performed, a yaw rate detecting means uses a steering sensor that detects a steering angular velocity, and performs a correction control of a control gain by determining a relative direction between the steering angular velocity and a rate of change of the steering angular velocity. In this case, the same operation and effect as in the above embodiment can be obtained.

If the steering angle and the yaw rate, the rate of change of the steering angular velocity and the rate of change of the yaw rate are different in phase from the lateral acceleration of the vehicle and the rate of change of the lateral acceleration, respectively, filter processing is performed by using a low-pass filter or the like. May be corrected.

[0064]

As described above, the vehicle suspension system according to the present invention provides the damping characteristics of each shock absorber with a sprung mass.
Bounce rate based on vertical speed and vertical speed on both front and rear sprung
Pitch rate detected from degree difference and vertical speed on both left and right sprung
Control signal obtained from the roll rate detected from the difference
Control based on bounce only.
And sufficient control force can be obtained for pitch and roll
This improves ride comfort and handling stability
The effect of being able to do is obtained. Further, when the direction of the yaw rate detected by the yaw rate detecting means and the direction of the rate of change of the yaw rate are the same direction, the control gain of the rear wheel side damping characteristic is set higher than the control gain of the front wheel side damping characteristic, When the vehicle is traveling in the opposite direction, a gain correction control unit that sets the control gain of the rear wheel side damping characteristic lower than the control gain of the front wheel side damping characteristic is provided, without deteriorating the riding comfort of the vehicle when traveling straight. In addition, there is an effect that the steering stability of the vehicle during the steering operation can be improved.

[0065]

[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 an explanatory diagram illustrating a configuration of a vehicle suspension device according to an embodiment of the present invention.

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

FIG. 4 is a cross-sectional view showing a shock absorber applied to the 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 damping characteristic diagram 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 illustrating a main part of a control unit in the apparatus according to the embodiment.

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

FIG. 16 is a time chart illustrating an operation of a damping characteristic control unit in a control operation of the control unit in the example device.

FIG. 17 is a time chart showing an operation of a gain correction control unit in a control operation of the control unit in the embodiment device.

FIG. 18 is a map showing a correction function for correlating a change rate of a lateral acceleration and a control gain in another embodiment device.

[Description of Signs] a damping characteristic changing means b shock absorber c vehicle behavior detecting means d damping characteristic control unit e control means f yaw rate detecting means g gain correction control unit

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

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, sprung vertical speed detecting means for detecting sprung vertical speed , The sprung vertical speed detected by the vertical speed detecting means
From the bounce rate and the vertical velocity difference between both front and rear sprung
Detected from the detected pitch rate and the difference
Based on the control signal obtained from the released roll rate
A control unit having an attenuation characteristic control unit to control the damping characteristics of the shock absorbers, the yaw rate detecting means for detecting a yaw rate of the vehicle, is provided to the control means, the yaw rate direction and said detected by the yaw rate detecting means When the direction of the rate of change of the yaw rate is the same, the control gain of the rear-wheel damping characteristic is set higher than the control gain of the front-wheel damping characteristic. A vehicle suspension device comprising: a gain correction control unit that sets a control gain of the rear wheel side damping characteristic to be lower. 2. The vehicle suspension system according to claim 1, wherein said yaw rate detecting means comprises a lateral acceleration detecting means for detecting a lateral acceleration of the vehicle. 3. The vehicle suspension according to claim 1, wherein said yaw rate detecting means comprises steering angular velocity detecting means for detecting a steering angular velocity.