JPH06344747A - Vehicle suspension system - Google Patents

Abstract

PURPOSE:To secure a vehicle suspension system that has improved the extent of controllability in correcting any slippage in phase due to filtering by comparing the reference value of a period for a varying waveform of a damping characteristic control signal with the detected value, and performing such compensation control as adding or subtracting a value of the control signal. CONSTITUTION:This suspension system is provided with a control means (e) having a damping characteristic altering means (a) to be interposed between a car body and each wheel, a car behavior detecting means (c) and a damping characteristic basic control part (d) controlling a damping characteristic optimally on the basis of the signal found out of the car behavior detected value. In succession, a period detecting means (f) of varying waveforms in the control signal is compared with a period and reference period of this varying wave form in the control signal, and when the period of the varying waveform in the control signal is longer than the reference period, a specified value is added to this control signal, and when it is shorter than that, such a compensation control part (g) as subtracting the specified value from the control signal is installed there. With this constitution, any slippage in phase due to filtering of the control signal is corrected and thereby controllability is thus improvable.

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 the damping force characteristic of a shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension system for controlling a damping force characteristic of a shock absorber, for example, Japanese Patent Application Laid-Open No. 61-61600.
The one described in Japanese Patent No. 163011 is known.

In this conventional vehicle suspension system, the sprung vertical velocity is obtained from the sprung vertical acceleration detected by the acceleration sensor, and the sprung / unsprung relative velocity is detected. When the sign is a sign, the damping force characteristic is hard, and when the sign is a different sign, the damping force characteristic is soft, and the damping force characteristic control based on the skyhook theory is performed independently for each of the four wheels. It was

[0004]

However, in the above-mentioned conventional apparatus, the integration process or the low-pass filter process is performed in order to obtain the sprung vertical velocity from the sprung vertical acceleration as described above. In order to actually use the speed signal as a control signal, it is necessary to perform high-pass filter processing to prevent zero-point drift and low-pass filter processing to cut noise. There is a problem in that the phase of the vertical velocity waveform and the phase of the detected sprung vertical velocity signal waveform only match at a predetermined frequency, causing a phase shift in other regions, which deteriorates controllability. It was

The present invention has been made in view of the above-mentioned conventional problems, and provides a vehicle suspension system capable of improving a controllability by correcting a phase shift due to a filtering process of a control signal. The purpose is.

[0006]

To achieve the above object, the vehicle suspension system of the present invention is interposed between the vehicle body side and each wheel side, as shown in the claim correspondence diagram of FIG. The shock absorber b whose damping characteristic can be changed by the damping characteristic changing means a, the vehicle behavior detecting means c which detects the vehicle behavior, and the damping characteristic of each shock absorber b based on the control signal obtained from the vehicle behavior detection value. The control means e having the damping characteristic basic control section d for optimal control, the cycle detection means f for detecting the cycle of the fluctuation waveform of the control signal, and the cycle of the fluctuation waveform of the control signal and the reference cycle are compared, and A correction control unit g that adds a predetermined value to the control signal when the period of the fluctuation waveform is longer than the reference period, and subtracts the predetermined value from the control signal when the period of the fluctuation waveform of the control signal is shorter than the reference period.
And, the means provided with.

[0007]

In the vehicle suspension system of the present invention, as described above,
Correction control for adding or subtracting the value of the control signal is performed according to the cycle of the fluctuation waveform of the control signal.

That is, when the cycle of the fluctuation waveform of the control signal is longer than the reference cycle, the phase of the fluctuation waveform of the control signal is advanced with respect to the phase of the fluctuation waveform of the actual vehicle behavior. In the correction control unit, a predetermined value is added to the control signal, whereby the phase advance amount is corrected.

Contrary to the above, when the cycle of the fluctuation waveform of the control signal is shorter than the reference cycle, the phase of the fluctuation waveform of the control signal is delayed relative to the phase of the fluctuation waveform of the actual vehicle behavior. Therefore, in this case, the correction control unit subtracts a predetermined value from the control signal, whereby the phase delay is corrected.

[0010]

Embodiments 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 system of the embodiment, in which four shock absorbers SA are provided between the vehicle body and the four wheels. A vertical acceleration sensor (hereinafter referred to as a vertical G sensor) 1 that detects vertical acceleration is provided on the vehicle body in the vicinity of each shock absorber SA. Further, a control unit 4 is provided near the driver's seat to input a signal from each vertical G sensor 1 and 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-mentioned configuration. The control unit 4 comprises an interface circuit 4a, a CPU 4b, and a drive circuit 4c, and the interface circuit 4a includes the above-mentioned vertical G sensors 1 to The acceleration signal of is input. In the interface circuit 4a, a set of three filter circuits shown in FIG. 14 is provided for each upper and lower G sensor 1. That is,
The LPF1 is a low-pass filter circuit for integrating a signal indicating the acceleration sent from the vertical G sensor 1 and converting it into a sprung vertical velocity, the HPF is a high-pass filter for zero-point drift prevention, and the LPF2 is a signal. This is a low-pass filter circuit for removing noise in the high frequency range (30 Hz or higher).

Next, FIG. 4 is a sectional view showing the structure of the shock absorber SA.
A is a cylinder 30, a piston 31 defining the cylinder 30 into an upper chamber A and a lower chamber B, an outer cylinder 33 having a reservoir chamber 32 formed on the outer periphery of the cylinder 30, a lower chamber B and a reservoir chamber 32. Defining the base 34 and the piston 31
A guide member 35 that guides the sliding of the piston rod 7 that is connected to the vehicle, a suspension spring 36 that is interposed between the outer cylinder 33 and the vehicle body, and a bumper bar 37.

Next, FIG. 5 is an enlarged sectional view showing a portion of the piston 31, and as shown in this figure, the piston 31 is formed with through holes 31a and 31b, and each through hole is formed. An expansion side damping valve 12 and a compression side damping valve 20 that open and close 31a and 31b, respectively, are provided. Further, a stud 38 penetrating 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 a flow path (an expansion-side second flow path E, an expansion-side third flow path F, a bypass flow path G, and a compression-side second flow path J described later) that connects the upper chamber A and the lower chamber B with each other. A hole 39 is formed and this communication hole 3
An adjuster 40 for changing the flow passage cross-sectional area of the flow passage is rotatably provided inside the passage 9. Also, the stud 38
The communication hole 3 is formed on the outer peripheral portion of the communication hole 3 depending on the direction of fluid flow.
An expansion-side check valve 17 and a pressure-side check valve 22 that allow and block the flow passage formed by 9 are provided. The adjuster 40 is rotated by the pulse motor 3 via the control rod 70 (see FIG. 4). Further, the stud 38 is formed with a first port 21, a second port 13, a third port 18, a fourth port 14, and a fifth port 16 in order from the top.

On the other hand, in the adjuster 40, a hollow portion 19 is formed, a first lateral hole 24 and a second lateral hole 25 which communicate the inside and the outside are formed, and a vertical groove 23 is formed in the outer peripheral portion. There is.

Therefore, a through hole 31 is provided between the upper chamber A and the lower chamber B as a flow passage through which a fluid can flow in the extension stroke.
The inside of the extension side damping valve 12 is opened through b and the lower chamber B
To the extension side first flow path D, the second port 13, the vertical groove 23,
Via the expansion side second flow path E, which opens the outer peripheral side of the expansion side damping valve 12 to the lower chamber B via the fourth port 14, the second port 13, the vertical groove 23, and the fifth port 16. Then, the extension side check valve 17 is opened to reach the lower chamber B by way of the third side flow passage F extending to the lower chamber B and the third port 18, the second lateral hole 25, and the hollow portion 19. There are four channels, channel G. Further, as a flow path through which the 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 is used.
Flow path H, hollow portion 19, first lateral hole 24, first port 21
Via the pressure side check valve 22 to the upper chamber A, and the bypass flow to the upper chamber A via the hollow portion 19, the second lateral hole 25, and the third port 18. Road G
There are three channels.

That is, the shock absorber SA is constructed so that the damping characteristic can be changed in multiple stages with the characteristics shown in FIG. 6 on both the extension side and the compression side by rotating the adjuster 40. That is, as shown in FIG. 7, when the adjuster 40 is rotated 60 ° counterclockwise from the central position (hereinafter referred to as the soft position SS) where both the extension side and the compression side have soft characteristics, the extension side becomes hard. In the characteristic, the pressure side becomes the position where the soft side becomes the soft characteristic (hereinafter referred to as the extension side hard position HS). Conversely, when the adjuster 40 is rotated 60 ° clockwise, the pressure side becomes the hard characteristic and the extension side becomes the soft characteristic. The structure is such that it becomes a position (hereinafter referred to as a pressure side hard position SH).

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

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

First, step 101 is a step of reading the sprung vertical velocity Vn. As described above, the sprung vertical velocity Vn is obtained by comparing the vertical acceleration signals obtained from the vertical G sensors 1 with the filter circuits LPF1, HPF,
The sprung vertical velocity Vn is obtained by processing with the LPF 2, that is, the sprung vertical velocity Vn as a bounce component at positions near each wheel. The sprung vertical velocity Vn is given as a positive value when the sprung vertical acceleration is in the upward direction, and is given as a negative value when it is in the downward direction.

In the following step 102, it is judged whether or not the sprung vertical velocity Vn has reached the peak value. If YES, the process proceeds to step 103, and if NO, step 114.
Proceed to.

In step 103, the sprung vertical velocity Vn
The frequency determination time Tn for a quarter cycle of the fluctuation waveform of is calculated. That is, the timer count is started from the time when the sprung vertical velocity Vn crosses the zero point, and then the time until the sprung vertical velocity Vn reaches the peak value is counted. Then, this frequency judgment time Tn is stored and then updated until the sprung vertical velocity Vn reaches a peak value after crossing the zero point and a new frequency judgment time Tn is obtained.

In step 104, the frequency judgment time Tn
Is a quarter of the time of a quarter cycle at the reference frequency fc
It is determined whether it is the same as fc, and if YES, step 1
After proceeding to 05 and setting the expansion side correction coefficient Kn- _T and the compression side correction coefficient Kn- _C to 0, the routine proceeds to step 109, and if NO, the routine proceeds to step 106. The reference frequency fc means the frequency of the detected sprung vertical velocity Vn in phase with the actual sprung vertical velocity V.

In step 106, the expansion side correction coefficient Kn- _T and the compression side correction coefficient Kn- _C are obtained based on the following equations (1) and (2). _{Kn -T = 4V HT · X ·} (y / 360X) = (V HT / 90) · y ···· (1) Kn -C = 4V HC · X · (y / 360X) = (V HC / 90 ) ・ Y ・ ・ ・ ・ (2) y = (Df / logA) ・ logB + Df Incidentally, FIG. 16 is a diagram showing the phase characteristics of the fluctuation waveform of the sprung vertical velocity Vn with respect to the frequency, as shown in this figure. , X is a frequency of the sprung vertical velocity Vn, fc is a reference frequency, f is an arbitrary frequency, Df is a phase angle from the reference frequency fc at an arbitrary frequency f, and A is relative to the reference frequency fc. The ratio of the frequency f, B is the ratio of the frequency X to the frequency f, V _HT is the proportional range on the extension side, and V _HC is the proportional range on the pressure side.

In the following step 107, it is judged whether or not the frequency judgment time Tn is longer than the reference time 1 / 4fc, and if YES, the routine proceeds to step 108, and if NO, the routine proceeds to step 109.

In step 108, it is determined whether or not the sprung vertical velocity Vn is a positive value. If YES, the process proceeds to step 110, where a correction coefficient Kn _-T on the extension side is used as a correction coefficient.
Is set to a positive value, and if NO, the routine proceeds to step 111, where the correction coefficient K on the pressure side is used as the correction coefficient.
Use n- _C and set it to a negative value, then
Go to 4.

In step 109, it is determined whether or not the sprung vertical velocity Vn is a positive value. If YES, the process proceeds to step 112, where a correction coefficient Kn _-T on the extension side is used as a correction coefficient.
Is set to a negative value, and if NO, the routine proceeds to step 113, where the correction coefficient K on the pressure side is set as the correction coefficient.
Use n- _C and set it to a positive value, then
Go to 4.

In step 114, the sprung vertical velocity Vn
Is a positive value, and if YES, step 1
15. If NO, proceed to step 116.

At step 115, the pulse motor 3 is driven so that the damping characteristic position of the shock absorber SA becomes the target damping characteristic position P obtained based on the following equation (3). _{P = (Vn + Kn -T /} V HT + Kn -T) × P T max ·············· (3) In addition, V _HT is the extension side of the proportional range, P _T max Is the maximum damping characteristic position on the extension side.

In step 116, the pulse motor 3 is driven so that the damping characteristic position of the shock absorber SA becomes the target damping characteristic position P obtained based on the following equation (4).

[0030] _{P = {(Vn -Kn -C)} / (V HC -Kn -C)} × P C max ········· (4) In addition, V _HC is proportional range of the pressure side, P _C max is the maximum damping characteristic position on the compression side.

With the above, one control flow is completed, and thereafter, the above steps are repeated.

Next, a phase shift correction control operation in the control unit 4 will be described with reference to a time chart. (A) At reference frequency When the frequency of the fluctuation waveform of the sprung vertical velocity Vn is the same as the reference frequency fc (Tn = 1 / 4fc), the phase of the detected sprung vertical velocity Vn is the actual sprung vertical velocity. Since it matches the phase of V, in this case, the values of the correction coefficients Kn _{- T} and Kn- _{C in} the equations (3) and (4) are set to zero.

Therefore, in this case, the target damping characteristic position P is set based on the following equations (3 ') and (4'). [Vn> 0] P = (Vn / _VHT ) × _PT max ..... (3 ') [Vn <0] P = (Vn / _VHC ) × P _C max ······ (4 ') That is, when the sprung vertical velocity Vn changes as shown in FIG. 17, the sprung vertical velocity Vn is 0. At some time, the damping characteristic position of the shock absorber SA is set to the soft position SS (position where the rotation angle of the pulse motor 3 is 0).
To control.

Further, when the sprung vertical velocity Vn is a positive value, the extension side hard position HS is switched to, and the extension side target damping characteristic position P is set based on the above equation (3 '). It That is, when the value of the sprung vertical velocity Vn becomes the proportional range V _HT on the extension side, the damping characteristic control proportional to the sprung vertical velocity Vn such that the maximum damping characteristic position P _T max on the extension side is obtained. Done.

When the sprung vertical velocity Vn is a negative value, the pressure side hard position SH is switched to, and the pressure side target damping characteristic position P is set based on the above equation (4 '). That is, when the value of the sprung vertical velocity Vn falls within the proportional range V _HC on the pressure side, the damping characteristic control proportional to the sprung vertical velocity Vn is performed such that the maximum damping characteristic position P _C max on the pressure side is reached. ..

In FIG. 17, in the area a, the sprung vertical velocity Vn is from a negative value (downward) to a positive value (upward).
However, at this time, since the relative speed is a negative value (the stroke of the shock absorber SA is on the pressure stroke side), the sprung vertical velocity Vn
The shock absorber SA is controlled to the extension side hard position HS based on the direction of
Then, the pressure stroke side, which is the stroke of the shock absorber SA at that time, has a soft characteristic.

In the region b, the sprung vertical velocity Vn remains a positive value (upward), and the relative velocity is switched from a negative value to a positive value (the stroke of the shock absorber SA is the extension stroke side). Since it is a region, at this time, the sprung vertical velocity Vn
The shock absorber SA is controlled to the extension side hard position HS based on the direction of, and the stroke of the shock absorber is also the extension stroke. Therefore, in this area b, the extension side of the shock absorber SA at that time is It has hard characteristics.

In region c, the sprung vertical velocity Vn is reversed from a positive value (upward) to a negative value (downward), but at this time, the relative velocity is still positive (shock absorber SA). Since the stroke is on the extension side), at this time, the shock absorber SA is controlled to the compression side hard position SH based on the direction of the sprung vertical velocity Vn. Therefore, in this area c The extension side, which is the stroke of the shock absorber SA at that time, has soft characteristics.

The area d is an area in which the sprung vertical velocity Vn remains a negative value (downward) and the relative velocity changes from a positive value to a negative value (the stroke of the shock absorber SA is on the extension side). Therefore, at this time, the shock absorber SA is controlled to the compression side hard position SH based on the direction of the sprung vertical velocity Vn, and the stroke of the shock absorber is also the pressure stroke. The pressure characteristic side of the shock absorber SA has a hard characteristic.

The regions other than the regions a, b, c and d are controlled to the soft position SS by the threshold control, or the hard positions H on both the extension side and the compression side.
It is in the state of being switched from S, SH to the soft position SS.

As described above, in this embodiment, when the sprung vertical velocity and the relative velocity between the sprung and unsprung have the same sign (region b, region d), the shock absorber S at that time.
Damping force characteristic control based on the skyhook theory, in which the stroke side of A is controlled to have a hard characteristic, and when the signs are different (area a, area c), the stroke side of the shock absorber SA at that time is controlled to have a soft characteristic. The same control as above is performed without detecting the relative speed between the sprung and unsprung parts. Further, in this embodiment, when the region a shifts to the region b and the region c shifts to the region d, the damping force characteristic is switched without driving the pulse motor 3.

(B) When the frequency is lower than the reference frequency When the frequency of the fluctuation waveform of the sprung vertical velocity Vn is lower than the reference frequency fc (Tn> 1 / 4fc), FIG.
As shown in FIG. 8, the phase of the detected sprung vertical velocity Vn is ahead of the actual phase of the sprung vertical velocity V.

In this case, the values of the expansion _- side correction coefficient Kn- _T in the equation (3) and the compression _- side correction coefficient Kn- _C in the equation (4) are the same as those in the equations (1) and (2). ), And when the sprung vertical velocity Vn is a positive value, the expansion side correction coefficient Kn- _T is set to a positive value, and when the sprung vertical velocity Vn is a negative value. The pressure side correction coefficient Kn- _C is set to a negative value.

That is, the sprung vertical velocity Vn changes from a positive value to 0.
Even at, not the target damping characteristic position P 0, the extension phase hard position HS side correction coefficient Kn of extension side _- have been kept in the damping characteristic position P _T corresponding to _T, then the spring The target damping characteristic position P becomes 0 only when the vertical velocity Vn switches to a negative value and changes by the pressure-side correction coefficient Kn- _C .

Similarly, even if the sprung vertical velocity Vn becomes 0 from a negative value, the target damping characteristic position P does not become 0, and the correction coefficient Kn _-C on the pressure side is set on the pressure side hard position SH side. The target damping characteristic position P is not maintained until the sprung vertical velocity Vn switches to a positive value and changes by an amount corresponding to the correction coefficient Kn- _T on the extension side after being maintained at the corresponding damping characteristic position P _C. It will be 0.

As described above, the phase advance of the detected sprung vertical velocity Vn with respect to the actual sprung vertical velocity V can be offset by the delay of the phase of the control waveform of the target damping characteristic position P.

(C) At a frequency higher than the reference frequency When the frequency of the fluctuation waveform of the sprung vertical velocity Vn is higher than the reference frequency fc (Tn <1 / 4fc), FIG.
As shown in FIG. 9, the phase of the detected sprung vertical velocity Vn is delayed from the actual phase of the sprung vertical velocity V.

In this case, the values of the expansion side correction coefficient Kn- _T in the equation (3) and the compression side correction coefficient Kn- _C in the equation (4) are the same as those in the equations (1) and (2). In addition, when the sprung vertical velocity Vn is a positive value, the expansion side correction coefficient Kn- _T is set to a negative value, and when the sprung vertical velocity Vn is a negative value, the compression side is set. The correction coefficient Kn- _{C of} is set to a positive value.

That is, when the sprung vertical velocity Vn decreases from a positive peak value to a value corresponding to the expansion side correction coefficient Kn- _T , the target damping characteristic position P becomes 0, and thereafter,
When the sprung vertical velocity Vn becomes 0, the damping characteristic position P _-T has already moved to the compression side hard position SH side by the amount corresponding to the expansion side correction coefficient Kn _-T . Similarly, when the sprung vertical velocity Vn decreases from a negative peak value to a value corresponding to the pressure side correction coefficient Kn- _C ,
When the target damping characteristic position P becomes 0 and thereafter the sprung vertical velocity Vn becomes 0, the extension side hard position HS has already become equal to the correction coefficient Kn- _C on the compression side.
It becomes the damping characteristic position P _-C that has shifted to the side.

As described above, the phase delay of the detected sprung vertical velocity Vn with respect to the actual sprung vertical velocity V can be canceled by the phase advance of the control waveform of the target damping characteristic position P.

FIG. 20 shows the control operation when the low frequency (b) and the high frequency (c) are combined, and the correction control operation at each frequency is combined.

FIG. 21 is a time chart showing the control operation in the case where a plurality of peak values p ₁ and p ₂ occur during the time (crossing a half cycle) after the zero point is crossed until the next zero point is crossed. It is a chart, and in such a case, malfunction is prevented by updating the peak value from p ₁ to p ₂ , that is, by updating the period as the frequency determination time from t ₁ to t _2. be able to.

As described above, in this embodiment, the effects listed below can be obtained.

The controllability can be improved by correcting the phase shift of the sprung vertical velocity Vn with respect to the actual sprung vertical velocity V generated by the filtering process.

Compared with the conventional damping force characteristic control based on the skyhook theory, the switching frequency of the damping force characteristic is reduced, so that the control response can be improved and
The durability of the pulse motor 3 can be improved.

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

Although the embodiment has been described above, the specific structure is not limited to this embodiment, and the present invention includes a design change and the like without departing from the scope of the invention.

For example, although the embodiment has been described in the case where the maximum attenuation characteristic position is not changed by the frequency, the maximum attenuation characteristic position when the frequency is the same as the reference frequency is used as a reference, and when the frequency is lower than the reference frequency. Set the maximum attenuation characteristic position to a large value, and set the maximum attenuation characteristic position to a small value when the frequency is higher than the reference frequency.For example, change the maximum attenuation characteristic position value according to the frequency. Good.

Further, in the embodiment, the sprung vertical velocity signal is used alone as the control signal, but the control signal may take other factors such as the pitch rate and the roll rate into consideration.

Further, in the embodiment, the upper and lower G sensors are independently provided at the positions near the respective wheels, but only one sensor is required to perform only the bounce control of the vehicle.

Further, in the embodiment, the case where the sprung vertical velocity signal is used as the vehicle behavior is shown, but the invention can be applied to the control using other vehicle behavior signals such as the relative velocity between the sprung and unsprung velocity. it can.

Further, in the embodiment, when controlling the damping characteristic on one stroke side of the extension stroke side or the compression stroke side to the hard characteristic side, a shock absorber having a structure in which the other stroke side is fixed to the soft characteristic is used. Although the case is shown, the present invention can also be applied to the case of using a shock absorber having a structure in which the damping characteristics on the extension stroke side and the compression stroke side change simultaneously.

[0063]

As described above, in the vehicle suspension system of the present invention, the period of the fluctuation waveform of the control signal is compared with the reference period, and when the period of the fluctuation waveform of the control signal is longer than the reference period, the control signal is changed. By adding a predetermined value to the control signal, and by providing a correction control unit that subtracts the predetermined value from the control signal when the period of the fluctuation waveform of the control signal is shorter than the reference period, phase shift due to filtering of the control signal It is possible to obtain the effect of being able to make a correction to improve the controllability.

[Brief description of drawings]

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

FIG. 2 is a structural explanatory view showing a vehicle suspension device of an embodiment of the present invention.

FIG. 3 is a system block diagram showing a vehicle suspension system of the embodiment.

FIG. 4 is a cross-sectional view showing a shock absorber applied to the apparatus of the embodiment.

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

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

FIG. 7 is a damping force characteristic diagram corresponding to a rotation angle of a pulse motor in the shock absorber.

FIG. 8 is a K of FIG. 5 showing a main part of the shock absorber.
FIG.

FIG. 9 is an L of FIG. 5 showing a main part of the shock absorber.
It is a -L cross section and a MM cross section.

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 of the extension side hard position HS of the shock absorber.

FIG. 12 is a characteristic diagram of damping force at a soft position SS of the shock absorber.

FIG. 13 is a characteristic diagram of damping force of a pressure side hard position SH of the shock absorber.

FIG. 14 is a block diagram showing a signal processing filter circuit in the apparatus of the embodiment.

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

FIG. 16 is a phase characteristic diagram with respect to a vibration frequency of a vertical velocity on a detection spring.

FIG. 17 is a time chart showing the control operation of the control unit in the apparatus of the embodiment.

FIG. 18 is a time chart showing the correction control operation of the control unit in the embodiment apparatus.

FIG. 19 is a time chart showing the correction control operation of the control unit in the embodiment apparatus.

FIG. 20 is a time chart showing the correction control operation of the control unit in the embodiment apparatus.

FIG. 21 is a time chart showing the correction control operation of the control unit in the embodiment apparatus.

[Explanation of symbols]

 a damping characteristic changing means b shock absorber c vehicle behavior detecting means d damping characteristic basic control section e control means f cycle detecting means g correction control section

Claims (1)

[Claims] 1. A shock absorber which is interposed between a vehicle body side and each wheel side and whose damping characteristic can be changed by a damping characteristic changing means, a vehicle behavior detecting means for detecting a vehicle behavior, and a vehicle behavior detected value. A control means having a damping characteristic basic control unit for optimally controlling the damping characteristic of each shock absorber based on the obtained control signal, a cycle detecting means for detecting the cycle of the fluctuation waveform of the control signal, and a cycle of the fluctuation waveform of the control signal When the period of the control signal fluctuation waveform is longer than the reference period, a predetermined value is added to the control signal, and when the period of the control signal fluctuation waveform is shorter than the reference period, the control signal is set to the predetermined value. And a correction control unit that subtracts the value of.