JPH05169946A - Suspension device of vehicle - Google Patents

Abstract

PURPOSE:To provide a vehicle suspension device with which the condition of sprung and unsprung is correctly detected to enable to appropriately control damping coefficient and control responsiveness is improved to enable to improve both riding comfort and control stability. CONSTITUTION:At the time of controlling either stroke side of extension side or compression side so as to have high damping coefficient, when an acceleration signal value passing through a shock absorber (b) having a damping coefficient changing means (a) by which the other stroke side has a prescribed low damping coefficient and a high-pass filter (e) is under a prescribed threshold value, or the direction of the acceleration signal value is same as the direction of the sprung speed, the same stroke direction side as the sprung speed direction is controlled to have high damping coefficient. A damping coefficient control means (f) to control the damping coefficient on the same stroke side as the sprung speed direction to be a prescribed low damping coefficient up to inversion of the direction of the sprung speed when the direction of acceleration signal value is reverse to the sprung speed direction and the acceleration signal value is over a decided threshold value is provided.

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.

[0002]

2. Description of the Related Art Conventionally, as such a vehicle suspension device, for example, one disclosed in Japanese Patent Application Laid-Open No. 64-60411 is known.

This vehicle suspension system detects the damping force generated by the shock absorber, estimates the relative displacement from the signal strength of the damping force, and determines the relative road from the cycle when the relative displacement exceeds a predetermined threshold value. When the road is judged to be bad and the road is judged to be good, the low damping coefficient is controlled for a predetermined interval, and when the road is judged bad, the high damping coefficient is controlled for a predetermined interval. ..

[0004]

However, in such a conventional vehicle suspension system, the damping force is controlled by a signal (a damping force generated by the shock absorber) in which the sprung component and the unsprung component are mixed. Therefore, it is not possible to correctly determine whether it is time to perform vibration suppression control or control to absorb vibration to improve riding comfort, and inappropriate control is performed to improve riding comfort. However, there is a problem in that the tire may deteriorate or the ground contact of the tire may be deteriorated to deteriorate the steering stability.

In addition, since the interval time for determining the road surface condition is required, the damping coefficient control is delayed, which also causes deterioration of riding comfort and steering stability.

The present invention has been made in view of such a problem, and it is possible to accurately detect the sprung / unsprung state and perform appropriate damping coefficient control, and at the same time, control response. It is an object of the present invention to provide a vehicle suspension system which can improve the riding comfort and the steering stability.

[0007]

According to the present invention, as shown in the claim correspondence diagram of FIG. 1, a high damping coefficient is provided between a wheel of a vehicle and a vehicle body, and one stroke side of the extension side and the compression side has a high damping coefficient. When controlling, the shock absorber b having the damping coefficient changing means a having a predetermined low damping coefficient on the other stroke side, the sprung acceleration detecting means c for detecting the sprung acceleration of the vehicle, and the sprung speed are detected. From among the signals obtained from the sprung speed detecting means d and the sprung acceleration detecting means c,
A high-pass filter e that cuts low-frequency components including the sprung resonance frequency, and when the acceleration signal value passing through the high-pass filter e is less than a predetermined threshold value, or the direction of the acceleration signal value is the sprung speed direction. When the direction of the acceleration signal is the same, the signal for controlling the stroke direction side of the shock absorber b which is the same as the sprung speed direction to a high damping coefficient is output to the damping coefficient changing means a, and the direction of the acceleration signal value is the sprung speed direction When the acceleration signal value is equal to or greater than a predetermined threshold value, the damping on the stroke side of the shock absorber b which is the same as the sprung speed direction is reversed until the sprung speed direction is reversed. Damping coefficient control means f for outputting a signal for controlling the coefficient to a predetermined low damping coefficient to the damping coefficient changing means a.
And the means provided with.

[0008]

The function of the present invention will be described. The reference numerals in the description correspond to those in FIG. When the vehicle travels, the shock absorber b is subjected to input from both the unsprung part and the sprung part, and the stroke of the shock absorber b is performed.

At this time, if the unsprung vibration is not so severe, the acceleration signal value after passing through the high-pass filter e and removing the sprung frequency component is also small and does not exceed a predetermined threshold value. Therefore, the damping coefficient control means f performs control such that the shock absorber b, which has the same direction as the sprung speed, has a high damping coefficient on the stroke direction side and a low damping coefficient on the reverse stroke side to suppress the vibration on the spring.

That is, when the unsprung vibration is not severe on both bad and good roads (when there is no unsprung flutter)
In order to obtain steering stability, the shock absorber b carries out a stroke in the same direction as the sprung speed direction with a damping coefficient which suppresses vibration on the spring to obtain steering stability.

In this state, when there is an input from the road surface in the direction opposite to the sprung speed direction, this input is absorbed by the low damping coefficient of the shock absorber b to suppress the transmission to the sprung, and Improve comfort.

On the other hand, when the unsprung vibration is severe due to running on a rough road (when the unsprung part is flapping), the acceleration signal value after passing through the high-pass filter e to remove the sprung frequency component becomes large, The predetermined threshold will be exceeded.

In this case, when the direction of the acceleration signal value is the same as the sprung speed direction, the damping coefficient control means f causes the same stroke of the shock absorber b as the sprung speed direction as in the above case. The control is performed so that the direction side has a high damping coefficient and the reverse stroke has a low damping coefficient, whereby the fluttering under the spring is absorbed by the low damping coefficient of the shock absorber b, and the transmission to the sprung is suppressed. As a result, the riding comfort is improved, and the unsprung side can easily follow the road surface variation to improve the ground contact property of the tire.

Further, as described above, when the acceleration signal value exceeds the predetermined threshold value and the direction of the acceleration signal value is opposite to the sprung speed direction, the sprung speed direction is reversed. Until then, the damping coefficient control means f sets the predetermined damping coefficient on the stroke side of the shock absorber b, which is the same as the sprung speed direction. That is, when the unsprung vibration is severe, the unsprung vibration is absorbed by the low damping coefficient of the shock absorber b to suppress the transmission to the sprung part, thereby improving the riding comfort and the road surface fluctuation. The unsprung side of the tire is easily followed to improve the grounding property of the tire.

Further, in performing the above-mentioned control, damping coefficient control is performed at any time according to the input of the sprung velocity direction and the sprung acceleration signal value. Since there is no determination, high control responsiveness is obtained.

[0016]

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 the first embodiment of the present invention, in which 1 is a shock absorber of variable damping force type, 2 is a pulse motor, 3 is a sprung acceleration sensor, 4 is a high-pass filter, and 5 is a control. Shows a unit.

A total of four shock absorbers 1 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 1, and the stepwise driving changes the damping coefficient position of each shock absorber 1 in multiple stages.

The sprung acceleration sensor 3 is mounted on a sprung vehicle body, measures vertical acceleration on the spring, and outputs an electric signal corresponding to the detected acceleration (sprung acceleration G ₀ ). The sprung acceleration sensor 3 is also provided for each shock absorber 1.

The high-pass filter 4 cuts a low-frequency sprung resonance frequency component from the sprung acceleration G _{0. In} this embodiment, a high-frequency component having a frequency of 3 Hertz is used. A signal indicating the acceleration signal value G ₁ as the unsprung resonance frequency component is input to the control unit 5.

The control unit 5 constitutes a damping coefficient control means, and based on the input signal from the sprung acceleration sensor 3 and the sprung acceleration signal passed through the high pass filter 4, the shock absorber 1 is optimally damped. A control signal is output to the step motor 2 so as to obtain a coefficient. That is, the control unit 5 includes an interface circuit 5a, a CPU 5b, and a drive circuit 5c,
An output signal from a vertical acceleration sensor 3 as vertical acceleration detecting means is input to the interface circuit 5a. Further, the interface circuit 5a is provided with the high-pass filter 4, and a signal from the vertical acceleration sensor 3 is directly input to the CPU 5b and a system in which the signal is input via the high-pass filter 4 is provided. It is supposed to coexist.

Next, FIG. 3 is a sectional view showing the structure of the shock absorber 1. The shock absorber 1 is
A cylinder 30, a piston 31 defining the cylinder 30 into an upper chamber and a lower chamber B, an outer cylinder 33 having a reservoir chamber C formed on the outer periphery of the cylinder 30, a lower chamber B and a reservoir chamber C.
And a guide member 35 for slidingly guiding the piston rod 7 connected to the piston 31,
A suspension spring 36 interposed between the outer cylinder 33 and the vehicle body and a bumper bar 37 are provided.

More specifically, the shock absorber 1 has, as shown in FIG. 4, an expansion side inner groove 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. The first and second expansion-side flow paths D that open the inner and outer peripheral portions of the expansion-side damping valve 12 from the position 11 to reach the lower chamber B;
An expansion side second flow path E that opens the outer peripheral portion of the expansion side damping valve 12 from the position of the expansion side outer groove 15 to the lower chamber B via the port 13, the vertical groove 23, and the fourth port 14; 2 port 1
3, the expansion side third flow path F reaching the lower chamber B by opening the expansion side check valve 17 via the vertical groove 23 and the fifth port 16
And a bypass flow passage G reaching the lower chamber B via the third port 18, the second lateral hole 25 and the hollow portion 19, and the inside of the lower chamber B compressed in the pressure stroke. Of the pressure side damping valve 20 as a flow path through which the fluid of FIG.
And the pressure side first flow path H reaching the upper chamber A and the hollow portion 1
9, the pressure side second flow path J which opens the pressure side check valve 22 via the first lateral hole 24 and the first port 21 to reach the upper chamber A, the hollow portion 19, the second lateral hole 25 and the third Port 18
There are three flow paths, the bypass flow path G and the bypass flow path G that reach the upper chamber A via the.

Further, the adjuster 6 can switch the position of the damping coefficient in multiple stages among the three positions shown in FIGS. 5 to 7 based on its step rotation.

That is, the second position shown in FIG.
Position), the expansion side first flow path D and the compression side first flow path D
The flow passage H and the pressure-side second flow passage J are allowed to flow,
As a result, as shown in FIG. 9, the high damping coefficient (+
Xm) has a predetermined low damping coefficient on the compression side of the reverse stroke.

Next, in the first position (FIG. 8) shown in FIG. 6, the four flow paths D, E, F, G of the pressure stroke are
All of the three flow paths H, J, and G in the compression 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.

Next, in the third position (of FIG. 8) shown in FIG. 7, the expansion side first to third flow paths D, E, F and the compression side first flow path H can be circulated. According to FIG.
As shown in, the compression side has a high damping coefficient and the extension side in the reverse stroke has a predetermined low damping coefficient. And the first and third
The position side 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 force coefficient side can be proportionally changed according to the step rotation angle. There is.

That is, this shock absorber 1 is
By rotating the adjuster 6, the damping coefficient based on the rotation can be changed in multiple steps in the range from the low damping coefficient to the high damping coefficient with the characteristics shown in FIG. 12 on both the expansion side and the compression side. Is configured. Further, as shown in FIG. 8, when the adjuster 6 is rotated counterclockwise from the position where both the expansion side and the compression side have the low damping coefficient, only the expansion side changes to the high damping coefficient side, and conversely, When the adjuster 6 is rotated clockwise, only the compression side changes to the high damping coefficient side.

Next, the operation flow of the control unit 5 will be described based on the flow chart shown in FIG. 13 (with reference to the time chart shown in FIG. 14).

First, step 101 is a step of determining whether or not the unsprung fluttering is large, and it is determined whether or not the acceleration signal value G ₁ is less than a predetermined threshold value g.
If NO, the process proceeds to step 102, and if YES, the process proceeds to step 103.

At step 102, after the normal control of the damping coefficient is performed, one control flow is ended. In this normal control, control is performed such that the stroke side of the shock absorber 1 having the same direction as the sprung speed V ₀ has a high damping coefficient, and the reverse stroke side thereof has a predetermined low damping coefficient. There is.

Step 103 is a step of determining whether or not the direction of the sprung speed V ₀ is upward (V ₀ > 0). If YES, the process proceeds to step 104, and if NO, the process proceeds to step 105.

In step 104, it is judged whether or not the direction of the acceleration signal value G ₁ (the direction of flapping under the spring) is the same as the direction of the sprung speed V ₀ (V ₀ > 0), and if YES. If NO in step 106, step 1
Proceed to 07.

In step 106, the normal control of the damping coefficient is performed, and then one control flow ends. That is, returning to step 101, this normal control state is continued until the acceleration signal value G ₁ becomes equal to or greater than the predetermined threshold value g.

Step 107 is the shock absorber 1
After outputting a switching signal to the actuator 2 in order to switch the damping coefficient of No. 2 to a predetermined low damping coefficient (+ Xn), the process proceeds to step 108.

[0036] At step 108, whether the direction of the sprung speed V ₀ is downward (V ₀ ≦ _0), i.e., the direction of the sprung velocity V ₀ are reversed but determines whether, if YES, the this Then, the control flow ends once, and if NO, the process returns to step 107 and the low damping coefficient state is continued until the direction of the sprung speed V ₀ is upward (V ₀ ≧ 0).

In step 105, the acceleration signal value G
_It is judged whether or not the direction of ₁ (the direction of fluttering under the spring) is the same as the direction of the sprung speed V ₀ (V ₀ <0), and YE
If S, the process proceeds to step 109, and if NO, the process proceeds to step 110.

In step 109, after the normal control of the damping coefficient is performed, one control flow is ended. That is, returning to step 101, this normal control state is continued until the acceleration signal value G ₁ becomes equal to or greater than the predetermined threshold value g.

In step 110, a switching signal is output to the actuator 2 in order to switch the damping coefficient of the shock absorber 1 to a predetermined low damping coefficient -Xn, and then the routine proceeds to step 111.

In step 111, whether the direction of the sprung speed V ₀ is upward (V ₀ ≧ _0), i.e., the direction of the sprung velocity V ₀ are reversed but determines whether, if YES, the this Then, the control flow ends once, and if NO, the process returns to step 110 and the low damping coefficient state is continued until the direction of the sprung speed V ₀ is upward (V ₀ ≧ 0).

The control unit 5 repeats the above 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 when the vehicle is running, and FIG. 14A shows the acceleration signal value G
₁ and (B) in FIG. ₁ show the sprung speed V ₀ , and the solid line in (C) shows the damping coefficient switching position X, respectively.

(A) When the unsprung vibration is small: The acceleration signal value G ₁ (unsprung frequency component) obtained by cutting the sprung acceleration G _{0 from} low frequency components including the sprung resonance frequency is a predetermined threshold value ( When less than + g, -g),
Vibration under the spring is not severe (no flutter under the spring)
Therefore, the high damping coefficient (+ Xm, -Xm) is on the stroke side of the shock absorber 1 which is the same as the direction of the sprung speed V ₀ at that time.
The switching control (normal control) of the damping coefficient is performed so that

That is, a) As shown by c ₁ in FIG. 14, the acceleration signal value G ₁ (unsprung frequency component) is less than a predetermined threshold value (+ g, −g), and the sprung speed is The direction of V ₀ is upward (+)
, The extension side, which is in the same direction as the sprung speed V ₀ , has a high damping coefficient (+ Xm, −Xm), and the opposite compression side has a predetermined low damping coefficient (second position in FIG. 8). 9 position).

B) As shown by c ₂ in FIG. 14, the acceleration signal value G ₁ (unsprung frequency component) is a predetermined threshold value (+
g, −g) and the direction of the sprung speed V ₀ is downward (−), the compression side having the same direction as the direction of the sprung speed V ₀ has a high damping coefficient (−Xn). , And the opposite side is switched to the third position (the position in FIG. 8 and the position in FIG. 11) where the predetermined low damping coefficient is obtained.

Therefore, the unsprung state is accurately grasped by the acceleration signal value G ₁ from which the unsprung resonance frequency is removed, and when the unsprung vibration is not severe, the same shock as the direction of the sprung speed V ₀ at that time is obtained. A high damping coefficient is used on the stroke direction side of the absorber 1 to suppress the vibration of the sprung body (vehicle body) to improve the steering stability, and at the same time, in a direction opposite to the direction of the sprung speed V ₀ at that time. A feature that the stroke side of the shock absorber 1 has a predetermined low damping coefficient to absorb a road surface input in a direction opposite to the stroke direction during vibration control and prevent transmission to the vehicle body to improve riding comfort. have.

(B) When unsprung vibration is severe When the acceleration signal value G ₁ (unsprung frequency component) exceeds a predetermined threshold value (+ g, -g), unsprung vibration is severe. (Under spring fluttering is large)
In this case, different control is performed as follows in relation to the direction of the sprung speed V ₀ .

That is, a) The direction of the sprung speed V _{0 and} the direction of the acceleration signal value G ₁ are the same, and further, the acceleration signal value G ₁ exceeds a predetermined threshold value (+ g, -g). When the shock absorber 1 is present, the stroke of the shock absorber 1 is opposite to the direction of the sprung speed V ₀ at that time. That is, as shown by a ₁ in FIG. 14, when the sprung speed V ₀ and the acceleration signal value G ₁ are both upward, the shock absorber 1 is in a pressure stroke due to a large thrust from the unsprung side. As shown in a ₂ of FIG. 14, when the sprung speed V ₀ and the acceleration signal value G ₁ are both downward, the shock absorber 1 extends due to a large depression on the unsprung side.

Therefore, in this case, as in the case of the above (a), the high damping coefficient (+ Xm, -X) is set on the stroke side of the shock absorber 1 in the same direction as the sprung speed V ₀ at that time.
In m), normal control of the damping coefficient is performed so that the reverse stroke side has a low damping coefficient.

Therefore, the fluttering under the spring is absorbed by the low damping coefficient of the shock absorber 1 to suppress the transmission to the spring, thereby improving the riding comfort and following the road surface fluctuation on the unsprung side. Is facilitated and the ground contact property of the tire can be improved.

B) The direction of the acceleration signal value G ₁ is opposite to the direction of the sprung speed V ₀ , and further, the acceleration signal value G ₁ exceeds a predetermined threshold value (+ g, -g). When the shock absorber 1 is present, the stroke of the shock absorber 1 is in the same direction as the sprung speed V ₀ at that time. That is, b ₁ in FIG.
As shown in FIG. 14, when the sprung speed V ₀ is in the upward direction and the acceleration signal value G ₁ is in the downward direction, the shock absorber 1 is extended due to a large depression on the unsprung side, and the shock absorber 1 moves to b ₂ in FIG. As shown, when the direction of the sprung speed V ₀ is downward and the direction of the acceleration signal value G ₁ is upward, the shock absorber 1 is in a pressure stroke due to a large thrust from the unsprung side.

Therefore, in this case, until the direction of the sprung mass velocity V ₀ is reversed (half period of the sprung mass velocity waveform), the first position where both the extension side and the compression side have a predetermined low damping coefficient (Fig. 8 No. 1 and the position of FIG. 10).

Therefore, fluttering under the spring is absorbed by a predetermined low damping coefficient of the shock absorber 1 to suppress the transmission to the spring, thereby improving the riding comfort and the unsprung side against the road surface fluctuation. Has a feature that it can be easily followed and the ground contact property of the tire can be improved.

In this embodiment, the acceleration signal value G ₁
Since the road surface is judged depending on whether or not is equal to or more than the threshold value ± g, compared with the case where the current data and the previous data are compared, the interval time is unnecessary and the control response can be improved. Have

Next, a second embodiment of the present invention will be described. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. Only the differences will be described.

That is, in this embodiment, as shown in the flow chart of FIG. 15, steps 107 and 110 of the first embodiment shown in the flow chart of FIG.
In steps 207 and 210 respectively corresponding to the above, when the sprung speed V ₀ is equal to or higher than a predetermined threshold value ± Vn as shown in (b) of FIG. 14, the same as in the case of the first embodiment. The shock absorber 1 is switched to a predetermined low damping coefficient (+ Xn, -Xn), but the sprung speed V
_{When 0} becomes less than a predetermined threshold value ± Vn, (c) of FIG.
As shown by the dotted line, the damping coefficient of the shock absorber 1 is proportionally controlled in accordance with the sprung speed V ₀ within a predetermined low damping coefficient (+ Xn, −Xn). Note that in FIG. 15, ^N is a real number greater than 0.

Therefore, this embodiment is characterized in that it is possible to prevent the sudden change of the damping coefficient at the time of switching the stroke of the shock absorber 1 and further improve the riding comfort.

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 is a design change or the like within the scope not departing from the gist of the present invention. Included in the present invention.

[0059]

As described above, in the vehicle suspension system according to the present invention, when one of the extension side and the compression side is controlled to have a high damping coefficient, the other stroke side has a predetermined low damping coefficient. A shock absorber having a damping coefficient changing means,
When the acceleration signal value that has passed through the high-pass filter is less than a predetermined threshold value, or when the direction of the acceleration signal value is in the same direction as the sprung speed direction, the stroke direction side that is the same as the sprung speed direction is set high. Controlled to a damping coefficient, the direction of the acceleration signal value is opposite to the sprung speed direction, and
When the acceleration signal value is equal to or greater than a predetermined threshold value,
Until the sprung speed direction reverses, the unsprung vibration is caused by the configuration including damping coefficient control means for controlling the damping coefficient on the same stroke side as the sprung speed direction to a predetermined low damping coefficient. When it is not severe, the shock absorber controls the stroke in the same direction as the sprung speed direction with a high damping coefficient to suppress the vibration on the spring and suppresses the vibration on the sprung speed direction depending on the road surface condition. Controls the ride comfort by absorbing the unsprung force in the opposite direction with a low damping coefficient, while when the unsprung vibration is severe, the unsprung flutter is absorbed by the low damping coefficient of the shock absorber, and In addition to performing ride comfort improvement control that prevents transmission, it also performs steering stability improvement control that makes it easier for the unsprung side to follow road surface fluctuations and improves tire ground contact.
This has the effect of improving both steering stability and riding comfort, and further, in performing this damping coefficient control, depending on the direction of the sprung speed and the input of the acceleration signal value on the spring. Since the damping coefficient control is performed at any time, an effect that high control responsiveness can be obtained is also obtained.

[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 the first embodiment of the present invention.

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

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

5 is a cross-sectional view showing the state of the first position, (a) is a KK cross-sectional view of FIG. 3, (b) is a LL cross-sectional view of FIG. 3, (c).
FIG. 4 is a sectional view taken along line N-N of FIG. 3.

6 is a sectional view showing a state of the second position, (a) is a sectional view taken along the line KK of FIG. 3, (b) is a sectional view taken along the line LL of FIG. 3, (c).
FIG. 4 is a sectional view taken along line N-N of FIG. 3.

7 is a sectional view showing a state of a third position, (a) is a sectional view taken along the line KK of FIG. 3, (b) is a sectional view taken along the line LL of FIG. 3, (c).
FIG. 4 is a sectional view taken along line N-N of FIG. 3.

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 first embodiment device.

FIG. 13 is a flowchart showing an operation flow of the control unit of the first embodiment device.

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

FIG. 15 is a flowchart showing an operation flow of a control unit in the vehicle suspension system of the second embodiment of the present invention.

[Explanation of symbols]

 a damping coefficient changing means b shock absorber c sprung acceleration detecting means d sprung speed detecting means e high-pass filter f damping coefficient controlling means

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[Procedure amendment]

[Submission date] May 1, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

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.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

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.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

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.

[Procedure amendment 4]

[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 which is provided between a wheel of a vehicle and a vehicle body and has a predetermined low damping coefficient on the other stroke side when controlling one of the extension side and the compression side to a high damping coefficient. A shock absorber having a changing means, a sprung acceleration detecting means for detecting sprung acceleration of the vehicle and a sprung speed detecting means for detecting sprung speed, and a signal obtained from the sprung acceleration detecting means,
A high-pass filter that cuts low-frequency components including the sprung resonance frequency, and when the acceleration signal value that has passed through the high-pass filter is less than a predetermined threshold value, or the direction of the acceleration signal value is the same as the sprung speed direction. Direction, the signal for controlling the stroke direction side of the shock absorber, which is the same as the sprung speed direction, to a high damping coefficient is output to the damping coefficient changing means, and the direction of the acceleration signal value is opposite to the sprung speed direction. And the acceleration signal value is equal to or higher than a predetermined threshold value, the damping coefficient on the stroke side of the shock absorber, which is the same as the sprung speed direction, is reduced to a predetermined low value until the sprung speed direction reverses. And a damping coefficient control means for outputting a signal for controlling the damping coefficient to the damping coefficient changing means.