JPH07232527A - Vehicle suspension device - Google Patents

Abstract

PURPOSE:To improve deterioration of riding comfortability of a vehicle at the time of high frequency road surface input rather than an on-spring resonnance frequency band without spoiling a damping force characteristic control effect against road surface input in the spring resonance frequency band. CONSTITUTION:A first signal processing circuit (d) to acquire a spring speed signal of a spring resonance frequency band from a spring acceleration signal and a second signal processing circuit (e) to acquire an acceleration signal of an intermediate frequency band between the spring resonance frequency band and an unspring resonance frequency band from the spring acceleration signal are provided. Additionally, a damping force characteristic control means (g) having a basic control part (f) to control a damping force characteristic of each shock absorber (b) by a control signal in accordance with the spring speed signal of the spring resonance frequency band acquired by the first signal processing circuit (d) and a correction control part (h) to correct and control the damping force characteristic to the soft side for a specified period of time after the acceleration signal of the intermediate frequency band is lowered below a threshold after the time when the acceleration signal of the intermediate frequency band provided on the damping force characteristic control means (g) and acquired by the second signal signal processing circuit (e) are furnished.

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 the damping force characteristic of a shock absorber.

[0002]

2. Description of the Related Art Conventionally, a vehicle suspension system for controlling damping force characteristics is disclosed in, for example, Japanese Patent Laid-Open No. 4-353006.
Those described in page 4, column 9, lines 31 to 31, and page 7, FIG. 2 are known.

This conventional device uses the output signals of the sprung vertical acceleration sensors, which are provided independently on the four wheels on the spring of the vehicle.
It has a signal processing circuit that extracts the sprung speed signal corresponding to the sprung speed component in the sprung resonance frequency band and the acceleration component signal in the unsprung resonance frequency band, and controls the damping force characteristic of the shock absorber according to each signal. Basically, damping force characteristic control is performed based on the sprung speed signal in the sprung resonance frequency band, but if the acceleration component signal in the unsprung resonance frequency band becomes larger than a predetermined value, the damping force characteristic control is performed according to that value. By controlling the damping force characteristic to the hard side, the flapping under the spring can be suppressed.

[0004]

However, the above-mentioned conventional device has the following problems.

That is, in the conventional device, as shown in the characteristic diagram of the transmissibility on the spring with respect to the road surface input frequency shown in FIG.
Sprung velocity component signal and C
The sprung acceleration component signal of the part (unsprung resonance frequency band) is detected, and damping force characteristic control is performed based on both signals.
Due to the characteristics of the bandpass filter for obtaining the sprung mass velocity component signal of the A part, the sprung mass velocity component of the B part is out of phase with the actual sprung mass velocity, and moreover, on the high frequency side of the sprung resonance frequency band. Since the control gain becomes higher, a control force that is not suitable for the actual behavior on the spring is generated on the high frequency side of the sprung resonance frequency band, and as a result, the transmissibility deteriorates in the shaded portion indicated by B and the riding comfort is improved. Although it worsens, there is a problem that the deterioration of the riding comfort cannot be improved because the deterioration of the transmission rate to the spring cannot be detected.

Further, by controlling the damping force characteristic in accordance with the acceleration component signal in the unsprung resonance frequency band, the transmissibility characteristic to the unsprung portion for the road surface input frequency in the unsprung resonance frequency band is improved. Regarding the above-mentioned transmissibility, there is a problem that the peak level of the transmissivity of the C portion does not change, but the transmissivity to the sprung portion is deteriorated by the shaded portion indicated by.

The present invention has been made by paying attention to the conventional problems as described above. The sprung resonance frequency band can be controlled without spoiling the damping force characteristic control effect on the road surface input in the sprung resonance frequency band. Aims to provide a vehicle suspension system capable of improving deterioration of the riding comfort of the vehicle at the time of inputting a high frequency road surface.

[0008]

In order to achieve the above object, in the vehicle suspension system of the present invention, as shown in the claim correspondence diagram of FIG. 1, a damping force characteristic is interposed between the vehicle body and each wheel. The shock absorber b is formed so that the damping force characteristic can be arbitrarily changed by the changing means a, the sprung acceleration detecting means c for detecting the vertical sprung acceleration of the vehicle body, and the sprung acceleration obtained by the sprung acceleration detecting means c. A first signal processing circuit d for obtaining a sprung speed signal in the sprung resonance frequency band from the acceleration signal; and a sprung resonance frequency band and an unsprung resonance frequency band from the sprung acceleration signal obtained by the sprung acceleration detection means c. Each shock absorber is controlled by a second signal processing circuit e that obtains an acceleration signal in an intermediate frequency band between them and a control signal based on the sprung speed signal in the sprung resonance frequency band that is obtained by the first signal processing circuit d. A damping force characteristic control unit g having a basic control unit f for controlling the damping force characteristic of the solver b, and an acceleration signal in the intermediate frequency band provided in the damping force characteristic control unit g and obtained by the second signal processing circuit e are When exceeding a predetermined threshold value, after that, after decreasing below the threshold value, the correction control unit h for correcting and controlling the damping force characteristic to the soft side for a predetermined period.
And, the means provided with.

[0009]

In the vehicle suspension system of the present invention, the sprung acceleration signal of the vehicle body detected by the sprung acceleration detection means is processed by the first signal processing circuit to obtain the sprung speed signal in the sprung resonance frequency band and attenuated. The basic control unit of the force characteristic control means controls the damping force characteristic of the shock absorber by the control signal based on the sprung speed signal. Therefore, by the damping force characteristic control corresponding to the road surface input in the sprung resonance frequency band,
The ride comfort of the vehicle can be secured.

When the acceleration signal in the intermediate frequency band between the sprung resonance frequency band and the unsprung resonance frequency band obtained by the second signal processing circuit exceeds a predetermined threshold value,
In the correction control unit, after that, the damping force characteristic is corrected and controlled to the soft side for a predetermined period after the voltage falls below the threshold value.

Therefore, the transmissibility to the sprung is deteriorated due to the phase difference between the actual sprung speed and the signal-processed sprung speed signal on the higher frequency side (intermediate frequency band) than the sprung resonance frequency band. Can be suppressed by lowering the damping force characteristic.

[0012]

Embodiments of the present invention will be described with reference to the drawings. (First Embodiment) First, the structure of a vehicle suspension system according to a first embodiment of the present invention will be described.

FIG. 2 is a structural explanatory view showing the vehicle suspension system of the first embodiment of the present invention, in which four shock absorbers SA are provided between the vehicle body and each wheel. A vertical acceleration sensor (hereinafter referred to as vertical G sensor) 1 for detecting vertical acceleration is provided on the vehicle body in the vicinity of each shock absorber SA. Then, at a position near the driver's seat, a control unit 4 which inputs a signal from each vertical G sensor 1 and outputs a drive control signal to the pulse motor 3 of each shock absorber SA.
Is provided.

The above configuration is shown in the system block diagram of FIG. 3, in which the control unit 4 comprises an interface circuit 4a, a CPU 4b and a drive circuit 4c. Signal is input.

In the interface circuit 4a, as shown in FIG. 14, a set of six signal processing circuits is provided for each of the upper and lower G sensors 1. That is, in the figure, the LPF 1 is a low-pass filter for removing noise in a high frequency region of 30 Hz or higher from the sprung acceleration G signal sent from the vertical G sensor 1. HPF1
Is a high-pass filter with a cut-off frequency of 3.0 Hz, L
PF2 is a low-pass filter with a cut-off frequency of 8.0 Hz. A band-pass filter (second signal processing) for obtaining a sprung acceleration signal Gn in an intermediate frequency band on the higher frequency side than the sprung resonance frequency band with both filters HPF1 and LPF2. Circuit). The LPF 3 is a low-pass filter for integrating the acceleration signal processed by the low-pass filter LPF 1 and converting it into a sprung mass velocity. HPF2 is a high-pass filter with a cutoff frequency of 0.8Hz, and LPF4 is a cutoff frequency of 2.0Hz.
Low pass filter, both filters HPF2, LPF4
To form a bandpass filter (first signal processing circuit) for obtaining the sprung mass velocity signal Vn in the sprung mass resonance frequency band.

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 cross-sectional view showing a portion of the piston 31. As shown in FIG. 5, the piston 31 has a through hole 31 for communicating the upper chamber A and the lower chamber B with each other.
a, 31b are formed, and each through hole 31a,
A compression side damping valve 20 and an expansion side damping valve 12 that open and close 31b are provided. In addition, the bound stopper 41 screwed to the tip of the piston rod 7
A stud 38 penetrating the piston 31 is screwed and fixed, and the stud 38 has an upper chamber A and a lower chamber B.
Is formed with a communication hole 39 for communicating with, and further, an adjuster 40 for changing the flow passage cross-sectional area of the communication hole 39 and a fluid flow on the communication hole 39 side are allowed depending on the fluid flow direction. An extension side check valve 17 and a pressure side check valve 22 for shutting off 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, between the upper chamber A and the lower chamber B, the inside of the extension side damping valve 12 is opened by passing through the through hole 31b as a flow passage through which the fluid can flow in the extension stroke. First side flow path D extending to B, second port 13, vertical groove 2
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 third and fourth ports 14, and the second
The extension side check valve 17 is opened via the port 13, the vertical groove 23, and the fifth port 16 to reach the lower chamber B.
Channel F, third port 18, second lateral hole 25, hollow portion 19
There are four flow paths, a bypass flow path G, which leads to the lower chamber B via. Also, as a flow path through which the fluid can flow in the pressure stroke,
The pressure-side first flow path H that opens the pressure-side damping valve 20 through the through hole 31a and the pressure-side check valve 22 through the hollow portion 19, the first lateral hole 24, and the first port 21 to open the upper chamber A. Pressure side second flow path J leading to the hollow part 19, the second lateral hole 2
5, There are three flow paths, a bypass flow path G reaching the upper chamber A via the third port 18.

That is, the shock absorber SA rotates the adjuster 40 so that the damping force characteristics based on the rotation are as shown in FIG. 6 for both the extension side and the compression side, and the low damping force is obtained. It is configured so that it can be changed in multiple stages from the characteristic (hereinafter referred to as software) to the high damping force characteristic (hereinafter referred to as hardware). In addition, as shown in FIG.
Adjuster 4 from the position where both pressure side was soft
When 0 is rotated counterclockwise (direction), only the extension side changes to the hard side, and conversely, when the adjuster 40 is rotated clockwise (direction), only the pressure side changes to the hard side. Has become.

Incidentally, in FIG. 7, the KK cross section, the MM cross section, and the NN cross section in FIG. 10 and the damping force characteristics at each position are shown in FIGS.

Next, among the operations of the control unit 4 for controlling the drive of the pulse motor 3, the switching operation between the basic control and the correction control will be described with reference to the flowchart of FIG. 15 and the time chart of FIG. Note that this control is separately performed for each shock absorber SA.

In the flowchart of FIG. 15, first,
In step 101, the sprung acceleration signal G at each wheel position is detected from each vertical G sensor 1. The sprung acceleration signal G is given a positive value in the upward direction and a negative value in the downward direction.

In step 102, the sprung acceleration signal G
Is processed by the signal processing circuit shown in FIG.
The sprung acceleration signal Gn in the intermediate frequency band on the higher frequency side than the sprung resonance frequency band is obtained.

In step 103, the absolute value | Gn | of the sprung acceleration signal in the intermediate frequency band is a predetermined threshold value G.
_It is determined whether or not _TH is exceeded, that is, whether or not the deterioration of the transmissibility to the sprung due to the phase shift between the actual sprung speed and the signal-processed sprung speed signal Vn occurs,
If YES, the routine proceeds to step 104, where the damping force characteristic correction control described later is performed, and if NO, the routine proceeds to step 105.

In step 105, it is determined whether or not the previous absolute value | Gn | of the sprung acceleration signal exceeds the predetermined threshold value G _TH , that is, the time point at which the absolute value | Gn | falls below the predetermined threshold value G _TH. If YES, the process proceeds to step 106, and if NO, the process proceeds to step 107.

In step 106, the timer count T _C of the delay timer is cleared to 0 to start the timer count, and then the process proceeds to step 104. In step 107,
The timer count T _C of the delay timer is the predetermined delay time T
It is determined whether or not it is less than _S. If YES, the process proceeds to step 108, and if NO, the process proceeds to step 109.

In step 108, 1 is added to the timer count T _C of the delay timer, and then the process proceeds to step 104. In step 109, basic control of damping force characteristics described later is performed.

That is, in this embodiment, as shown in the time chart of FIG. 16, the absolute value of the sprung acceleration signal in the intermediate frequency band on the higher frequency side than the sprung resonance frequency band.
When | Gn | exceeds the predetermined threshold value G _TH , the damping force characteristic of the step 104 is kept until the predetermined delay time T _S elapses after the threshold value G _TH is decreased below the threshold value G _TH . Correction control is performed.

[0030] Then, in the correction control, the damping force characteristic position of the shock absorber SA regardless of the value of the control signal V at that time, the control for fixing the preset lower damping force characteristic position P _L is performed .

As described above, the phase between the actual sprung speed and the signal-processed sprung speed signal Vn deviates on the high frequency side from the sprung resonance frequency band, and as a result, the high frequency side (intermediate side) from the sprung resonance frequency band. It is possible to suppress the deterioration of the transmissibility to the sprung portion in the frequency band) by lowering the damping force characteristic.

Next, the contents of the basic control of the damping force characteristic in step 109 will be described with reference to the flowchart of FIG. In step 201, each vertical G sensor 1
By processing the sprung acceleration signal G detected in 1. in the signal processing circuit shown in FIG. 14, a sprung speed signal Vn in the sprung resonance frequency band is obtained.

In step 202, the sprung speed signal Vn
From the above, the control signal V in the basic control is obtained based on the following equation (1).

V = Vn × α (1) where α is a control gain during basic control.

In step 203, it is determined whether the control signal V is a positive value, and if YES, step 20
4, the shock absorber SA is controlled to the extension side hard region HS, and if NO, the process proceeds to step 205.

In step 205, it is judged whether or not the control signal V is 0, and if YES, the routine proceeds to step 206, where the shock absorber SA is controlled to the soft region SS, and if NO, step 207. Proceed to.

In step 207, if it is determined to be NO in steps 203 and 205, that is, the control signal V
Is a processing step when the value is a negative value. In this step, the shock absorber SA is set to the compression side hard area SH.
To control.

Next, the contents of the basic control of damping force characteristics will be described with reference to the time chart of FIG. The control signal V is
In the case of the change as shown in this figure, when the control signal V is 0, the shock absorber SA is controlled to the soft region SS.

When the control signal V has a positive value, the extension side hard area HS is controlled to fix the compression side to the low damping force characteristic, while the extension side damping force characteristic is proportional to the control signal V. change. At this time, the extension side damping force characteristic position P _T
Is set to the position obtained based on the following equation (2) (see FIG. 16). P _T = (V / V _HT ) P _T max ········ (2) where V _HT is the extension side proportional range and P _T max is the extension side maximum damping force. It is a characteristic position.

When the control signal V becomes a negative value, the compression side hard region SH is controlled to fix the extension side to the low damping force characteristic, while the compression side damping force characteristic is changed in proportion to the control signal V. To do. At this time, the damping force characteristic position P _{C on the} compression side
Is set to the position obtained based on the following equation (3) (see FIG. 16). P _C = (V / V _HC ) P _C max ······ (3) V _HC is the proportional range on the pressure side, and P _C max is the maximum damping force characteristic position on the pressure side. Is.

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

The region b is a region where the control signal V remains a positive value (upward) and the relative speed is switched from a negative value to a positive value (the stroke of the shock absorber SA is the extension stroke side). Therefore, at this time, the shock absorber SA is controlled in the extension side hard region HS based on the direction of the control signal V, and the stroke of the shock absorber is also the extension stroke. Therefore, in this region, the shock at that time is present. The extension side, which is the stroke of the absorber SA, has a hardware characteristic proportional to the value of the control signal V.

In the area c, the control signal V is reversed from a positive value (upward) to a negative value (downward).
At this time, the relative speed is still a positive value (shock absorber S
Since the stroke of A is on the extension side), at this time, the shock absorber SA is controlled to the compression side hard zone SH based on the direction of the control signal V.
In this region, the extension side, which is the stroke of the shock absorber SA at that time, has soft characteristics.

In the area d, the control signal V 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 the extension 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 pressure stroke.
Therefore, in this area, the shock absorber SA at that time
The pressure stroke side, which is the stroke of, has a hardware characteristic proportional to the value of the control signal V.

As described above, in this embodiment, when the control signal V based on the sprung mass velocity signal Vn and the relative velocity between the sprung mass and the unsprung mass have the same sign (region b, region d), Damping force based on the skyhook theory, in which the stroke side of the shock absorber SA is controlled to have a hard characteristic, and when the shock absorber SA has a different sign (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 the characteristic control is performed without detecting the relative speed between the sprung part and the unsprung part. 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.

As described above, in the vehicle suspension system of this embodiment, the effects listed below can be obtained. Deterioration of the transmission rate to the sprung caused by the phase shift between the actual sprung speed and the signal-processed sprung speed signal in the intermediate frequency band can be suppressed by lowering the damping force characteristic. Therefore, it is possible to improve the deterioration of the riding comfort of the vehicle at the time of inputting a high frequency road surface above the sprung resonance frequency without impairing the damping force characteristic control effect on the road surface input in the sprung resonance frequency band.

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.

Next, another embodiment of the present invention will be described. It should be noted that these embodiments differ from the first embodiment in the content of the correction control in the control operation of the control unit 4, and other configurations are the same as those in the first embodiment. Only the points will be described.

(Second Embodiment) In the vehicle suspension system of the second embodiment, during correction control, as shown in FIG. 19, the maximum damping force characteristic position is lower than that during basic control. It is limited to P _L max, and the same effect as that of the first embodiment can be obtained.

(Third Embodiment) In the vehicle suspension system of the third embodiment, the control signal V during the basic control in the first embodiment is used.
Instead of this, the control similar to the basic control in the first embodiment is performed by the control signal V _L at the time of correction control obtained based on the following equation (4).

V _L = V n × β (4) Note that β is a control gain during correction control, and is a control gain α during basic control in the first embodiment. Is set to a lower value.

Therefore, in the correction control, as shown in FIG. 20, the damping force characteristic position P _L is set at a reduced ratio (β / α) with respect to the damping force characteristic position in the basic control. It will be.

Therefore, in this embodiment, the same effect as that of the first embodiment can be obtained, and since the correction control is proportional to the control signal V in the basic control, the input of the road surface in the sprung resonance frequency band is performed. The correction control is performed by making use of the result of the damping force characteristic control, whereby the ride comfort improving effect can be further enhanced.

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 within a range not departing from the gist of the invention.

For example, in the embodiment, when one of the extension side and the compression side is controlled to the high damping force characteristic side, the other is a shock absorber having a damping force characteristic changing means which is fixed to the low damping force characteristic. However, the damping force characteristic changing means having a structure in which the damping force characteristics change on both the extension side and the compression side may be used.

[0056]

As described above, in the vehicle suspension system of the present invention, the damping force characteristic of each shock absorber is controlled by the control signal based on the sprung speed signal in the sprung resonance frequency band obtained by the first signal processing circuit. When the acceleration signal in the intermediate frequency band obtained by the second signal processing circuit exceeds a predetermined threshold value, the damping force characteristic control means having a basic control unit for controlling By providing the correction control unit that corrects the damping force characteristics to the soft side for a predetermined period, the result is that the actual sprung speed signal and the signal-processed sprung speed signal are out of phase in the intermediate frequency band. The deterioration of the transmissibility to the sprung can be suppressed by lowering the damping force characteristic, and therefore the damping force characteristic control effect for the road surface input in the sprung resonance frequency band can be impaired. The teeth, the effect is obtained that is from the sprung resonance frequency will be able to improve the riding comfort deterioration of the vehicle at the time of induction road surface input.

[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 the first embodiment of the present invention.

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

FIG. 4 is a sectional view showing a shock absorber applied to the device of the first 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 the step position of the pulse motor of 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 LM 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 of the shock absorber when the extension side is hard.

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

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

FIG. 14 is a block diagram showing a configuration of a signal processing unit inside a CPU in the first embodiment device.

FIG. 15 is a flowchart showing a switching operation between basic control and correction control among control operations of the control unit in the first embodiment device.

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

FIG. 17 is a flowchart showing the contents of basic control in the control operation of the control unit in the first embodiment device.

FIG. 18 is a time chart showing the contents of basic control in the control operation of the control unit in the first embodiment device.

FIG. 19 is a time chart showing the control operation of the control unit in the second embodiment device.

FIG. 20 is a time chart showing the control operation of the control unit in the device of the third embodiment.

FIG. 21 is a transmissivity characteristic diagram of a shock absorber on a spring with respect to a road surface input frequency in a conventional example.

[Explanation of symbols]

 a damping force characteristic changing means b shock absorber c sprung acceleration detecting means d first signal processing circuit e second signal processing circuit f basic control section g damping force characteristic control means h correction control section

Claims (1)

[Claims] 1. A shock absorber, which is interposed between a vehicle body and each wheel and is formed so that the damping force characteristic can be arbitrarily changed by a damping force characteristic changing means, and a sprung body for detecting a vertical sprung acceleration of the vehicle body. Acceleration detection means, a first signal processing circuit for obtaining a sprung speed signal in a sprung resonance frequency band from a sprung acceleration signal obtained by the sprung acceleration detection means, and a sprung acceleration signal obtained by the sprung acceleration detection means A second signal processing circuit for obtaining an acceleration signal in an intermediate frequency band between the sprung resonance frequency band and the unsprung resonance frequency band, and a sprung speed signal in the sprung resonance frequency band obtained by the first signal processing circuit. Damping signal characteristic control means having a basic control part for controlling the damping force characteristic of each shock absorber by the control signal, and the second signal processing provided in the damping force characteristic control means. When the acceleration signal in the intermediate frequency band obtained by the circuit exceeds a predetermined threshold value, after that, the correction control unit corrects and controls the damping force characteristic to the soft side for a predetermined period after decreasing below the threshold value, A vehicle suspension device comprising: