JP3075494B2 - Vehicle suspension system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension system for optimally controlling a damping characteristic of a shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension device for controlling damping characteristics of a shock absorber, for example, Japanese Unexamined Patent Publication No.
What is described in 163011 is known.

This conventional vehicle suspension detects a sprung vertical speed and a sprung / unsprung relative speed. When both have the same sign, the damping characteristic is hard, and when both have different signs, the damping characteristic is set. Damping characteristic control such as softening is performed independently for four wheels.

[0004]

However, in the above-described conventional apparatus, the above-described configuration has the above-described structure. Therefore, when the hardware characteristics are suitable when the vehicle body is moving in the bounce direction, For body motion in which bouncing and pitching are coupled, the sprung mass is subjected to the body moment of inertia around the center of gravity of the body, resulting in insufficient damping force (control force) and poor steering stability. There was a point.

In addition, since the sprung vertical speed signal causes a phase shift (delay) with respect to the vehicle behavior, there has been a problem that the control responsiveness is deteriorated particularly with respect to a high frequency input.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has a sufficient vibration damping property with respect to a moment of inertia while securing the riding comfort of the vehicle, thereby achieving a stable driving of the vehicle. It is an object of the present invention to provide a vehicle suspension device capable of improving responsiveness and improving control response to a high-frequency input.

[0007]

In order to achieve the above object, a vehicle suspension system according to a first aspect of the present invention, as shown in the claim correspondence diagram of FIG. A shock absorber b whose damping characteristic can be changed by damping characteristic changing means a; a sprung vertical acceleration detecting means c for detecting a sprung vertical acceleration near a position where each shock absorber b is provided; b
, A sprung vertical speed detecting means d for detecting a sprung vertical speed near a position provided with a bounce component, a bounce component detecting means e for detecting a bouncing component of the vehicle body, and a pitch component detecting means f for detecting a pitch component of the vehicle body. And a roll component detecting means g for detecting a roll component of the vehicle body, a vehicle speed detecting means h for detecting a vehicle speed, and a damping characteristic of each shock absorber b.
A bounce rate, a pitch rate, and a roll rate obtained by multiplying a bounce component, a pitch component, and a roll component by a predetermined proportionality constant; and a sprung vertical acceleration applied to at least one of the bounce component, the pitch component, and the roll component. A damping characteristic control means j for controlling based on a control signal obtained by a correction component obtained by multiplying a predetermined proportional constant based on
A proportional constant correction unit k for increasing a proportional constant multiplied by the sprung vertical acceleration as the vehicle speed increases.

A vehicle suspension system according to a second aspect is provided with a shock absorber b interposed between the vehicle body side and each wheel side and capable of changing the damping characteristic by damping characteristic changing means a, and each shock absorber b. A sprung vertical acceleration detecting means c for detecting a sprung vertical acceleration near a position where the shock absorber b is provided; a sprung vertical speed detecting means d for detecting a sprung vertical speed near a position where each shock absorber b is provided; Relative speed detecting means m for detecting a relative speed between sprung and unsprung portions near the position where the absorber b is provided;
Bounce component detecting means e for detecting a bouncing component of the vehicle body
And pitch component detecting means f for detecting a pitch component of the vehicle body
And roll component detecting means g for detecting a roll component of the vehicle body
A vehicle speed detecting means h for detecting a vehicle speed, and a damping characteristic of each shock absorber b, a bounce rate, a pitch rate, and a roll rate obtained by multiplying a bounce component, a pitch component, and a roll component by a predetermined proportional constant. At least one of a bounce component, a pitch component, and a roll component
A control signal is obtained by a correction component obtained by multiplying a predetermined proportionality constant based on the sprung vertical acceleration added to the control signal, and when the control signal and the relative speed between the sprung and unsprung have the same sign, the damping characteristic is determined. On the other hand, when the sign is different, a damping characteristic control means j for controlling the damping characteristic to a minimum, and a proportional coefficient provided in the damping characteristic control means j for increasing a proportional constant for multiplying the sprung vertical acceleration as the vehicle speed increases. A constant correction unit k.

The pitch component detecting means may be a means for detecting a pitch component from a sprung vertical speed difference between the front and rear of the vehicle body based on the sprung vertical speed detected by the sprung vertical speed detecting means. May be a means for detecting a roll component from a difference between left and right sprung vertical speeds of the vehicle body based on a sprung vertical speed detected by the sprung vertical speed detecting means.

Further, a correction component of a pitch component is obtained from a difference between a sprung vertical acceleration of the vehicle front and rear based on a sprung vertical acceleration detected by the sprung vertical acceleration detecting means. The correction component of the roll component may be obtained from the difference between the sprung vertical acceleration of the left and right sides of the vehicle based on the vertical acceleration.

[0011] The shock absorber may further include a compression-side hard region in which the extension side has a variable damping characteristic and a compression side in which the compression side is fixed to low attenuation characteristics, a compression-side hard region in which the compression side has a variable attenuation characteristic and the extension side is fixed to have a low attenuation characteristic, The damping characteristic control means is formed in a structure having three regions of a soft region having low damping characteristics on both the side and the pressure side, and the damping characteristic control means controls the shock absorber in the extension side hard region when the control signal is equal to or more than a positive threshold value. When the control signal is equal to or less than the negative threshold, the shock absorber is controlled in the pressure side hard region, and when the control signal is between the positive and negative thresholds, the shock absorber is controlled in the soft region. Is also good. In obtaining the control signal, a bounce component and a correction component added to the bounce component are obtained by using a signal passed through a band-pass filter including a sprung resonance frequency of each of the front and rear wheels, and a pitch component and a correction component added to the pitch component are used. The component uses a signal passed through a band-pass filter containing the pitch resonance frequency,
The roll component and the correction component added to the roll component are:
A signal passed through a band-pass filter including the roll resonance frequency may be used.

In obtaining the control signal,
A first proportional constant to be applied to the bounce component to which the correction component has been added, and a second proportional constant to be applied to the pitch component to which the correction component has been added.
And a third proportional constant multiplied by the roll component to which the correction component is added are set independently of each other. The first proportional constant is a numerical value corresponding to the vertical spring constant,
May be a numerical value according to the pitch rigidity, and the third proportional constant may be a numerical value according to the roll rigidity.

[0013]

The vertical movement of the spring (bouncing), pitching, and the like can be obtained by means of each sprung vertical speed detecting means, bounce component detecting means, pitch component detecting means and roll component detecting means.
When a roll is detected, the damping characteristic control means multiplies the bounce component, the pitch component, and the roll component by a predetermined proportional constant, and calculates a bounce rate, a pitch rate, and a roll rate, and the bounce component, the pitch component, and the roll component. A control signal is obtained by a correction component obtained by multiplying a predetermined proportional constant based on at least one of the sprung vertical acceleration, and the damping characteristic of each shock absorber is controlled according to the control signal.

Therefore, a sufficient control force can be obtained not only for the bounce but also for the pitch and the roll, and the steering stability of the vehicle can be secured.

In the proportional constant correction section, a correction is made to increase the value of the proportional constant multiplied by the correction component as the vehicle speed increases. By changing the proportional constant, a lower value is obtained at low vehicle speeds. The ride comfort of the vehicle can be ensured by a lower damping characteristic based on the proportional constant, and the steering stability of the vehicle can be ensured at a high vehicle speed by the higher damping characteristic based on the higher proportional constant.

Further, the correction component based on the sprung vertical acceleration becomes larger as the vibration frequency of the vehicle body increases, and the phase is always advanced with respect to each component based on the sprung vertical speed. Control responsiveness to high-frequency input is improved.

Further, in the apparatus according to the second aspect, the damping characteristic control means increases the damping characteristic when the control signal and the relative speed between the sprung and unsprung parts have the same sign. In some cases, the attenuation characteristics are minimized. In this case as well, sufficient control force can be obtained not only for the bounce but also for the pitch and the roll, and the driving stability of the vehicle at a high vehicle speed is ensured while ensuring the riding comfort of the vehicle at a low vehicle speed. In addition, control responsiveness to a high-frequency input is improved.

[0018]

An embodiment of the present invention will be described with reference to the drawings. (First Embodiment) First, the configuration will be described.

FIG. 2 is a structural explanatory view showing a vehicle suspension system of a first embodiment which is an embodiment of the invention according to the first, third, fourth, fifth, sixth, and seventh aspects of the present invention. Between the four shock absorbers SA ₁ , SA ₂ , S
A ₃ , SA ₄ (when describing the shock absorber in a collective manner, and when describing the common configuration thereof, simply refer to SA). A vertical acceleration sensor (hereinafter, referred to as a vertical G sensor) 1 for detecting a sprung vertical acceleration is provided on the vehicle body in the vicinity of each shock absorber SA.
Is provided. In addition, a signal from each sensor 1 is input to a position near the driver's seat, and each shock absorber S
A control unit 4 for outputting a drive control signal to the A pulse motor 3 is provided.

FIG. 3 is a system block diagram showing the above configuration. The control unit 4 includes an interface circuit 4a, a CPU 4b, and a drive circuit 4c. And the signal from the vehicle speed sensor 5 are input.
In the interface circuit 4a, a set of seven filter circuits shown in FIG. That is, the first LPF is a low-pass filter circuit for removing high-frequency (30 Hz or more) noise from signals transmitted from the upper and lower G sensors 1. B
The PF1 passes a frequency range including a sprung resonance frequency and bounces a sprung vertical acceleration bounce component signal a (a ₁ , a
₂ , _a3 , _a4 The numbers ₁ , ₂ , ₃ , and ₄ correspond to the positions of the respective shock absorbers SA. The same applies to the following. ) Is a band-pass filter circuit. BP
F2 passes a frequency component including a pitch resonance frequency, and transmits a pitch component signal a ′ (a ₁ ′, a
₂ ′, a ₃ ′, a ₄ ′). The BPF ₃ is a band-pass filter circuit that passes a frequency range including a roll resonance frequency to form a roll component signal a ″ (a ₁ ″, a ₂ ″, a ₃ ″, a ₄ ″) of a sprung vertical acceleration. The second LPF 1 integrates the bounce component signal a of the sprung vertical acceleration that has passed through the band-pass filter circuit BPF1, and integrates the bounce component signal v (v ₁ , v ₂ , v ₃ , v _{4 of} the sprung vertical speed.
The numbers ₁ , ₂ , ₃ , and ₄ correspond to the positions of the respective shock absorbers SA. The same applies to the following. ) Is a low-pass filter circuit. The second LPF 2 integrates the pitch component signal a ′ of the sprung vertical acceleration that has passed through the band-pass filter circuit BPF2, and integrates the pitch component signal v ′ (v ₁ ′, v ₂ ′, v ₃ ′, v) of the sprung vertical speed. ₄ ') is a low-pass filter circuit for conversion. 2nd LPF
3 integrates a roll component signal a ″ of the sprung vertical acceleration that has passed through the band-pass filter circuit BPF3 and integrates a roll component signal v ″ (v ₁ ″, v ₂ ″, v) of the sprung vertical speed.
₃ ″, v ₄ ″). Incidentally, in the present embodiment, the case where the sprung resonance, the pitch resonance, and the roll resonance have different frequencies is taken as an example. However, when these resonance frequencies are similar,
The band-pass filter and the second low-pass filter are BP
Only F1 and the second LPF1 may be used.

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

FIG. 5 is an enlarged sectional view showing a part of the piston 31. As shown in FIG. 5, the piston 31 has through holes 31a and 31b formed therein, and A compression-side damping valve 20 and an extension-side damping valve 12 for opening and closing 31a and 31b, respectively, are provided. In addition, a flow path that connects the upper chamber A and the lower chamber B by bypassing the through holes 31a and 31b is provided in the axial center portion of the piston rod 7 that penetrates the piston 31 (the extension side second passage described later).
A communication hole 39 for forming the flow path E, the third flow path F on the extension side, the bypass flow path G, and the second flow path J on the compression side is formed.
An adjuster 40 for changing the cross-sectional area of the flow path is rotatably provided in the communication hole 39. Also,
On the outer peripheral side of the piston rod 7, the flow on the side of the flow path formed by the communication hole 39 is allowed according to the direction of flow of the fluid.
The extension side check valve 17 and the pressure side check valve 22 which shut off are provided. The adjuster 40 is rotated by the pulse motor 3 (see FIG. 4). In addition, the first port 21, the second port 13, the third port 18,
A fourth port 14 and a fifth port 16 are formed.

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

Therefore, between the upper chamber A and the lower chamber B, as a flow path through which fluid can flow during the extension stroke, the inside of the extension side damping valve 12 which passes through the through hole 31b is opened to open the lower chamber. B, the first port D on the extension side, the second port 13 and the flute 2
(3) a second expansion passage (E) that opens the outer peripheral side of the expansion damping valve (12) through the fourth port (14) to reach the lower chamber (B);
The extension side check valve 17 is opened via the port 13, the vertical groove 23, and the fifth port 16, and the extension side third valve reaching the lower chamber B is opened.
The flow path F, the third port 18, the second lateral hole 25, and the hollow portion 19
There are four flow paths of a bypass flow path G which leads to the lower chamber B via. Also, as a flow path through which fluid can flow in the pressure stroke,
The upper side chamber A is opened by opening the pressure side first flow path H passing through the through hole 31a and opening the pressure side damping valve 20, and opening the pressure side check valve 22 via the hollow portion 19, the first horizontal hole 24, and the first port 21. Pressure side second flow path J leading to the hollow portion 19, the second lateral hole 2
5, there are three flow paths: a bypass flow path G which reaches the upper chamber A via the third port 18.

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

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

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

In step 101, the upper and lower G sensors 1,
The vertical acceleration gg and the vehicle speed VV are read from 1, 1, 1 and the vehicle speed sensor 5.

In step 102, each of the upper and lower G sensors 1,
The vertical acceleration gg obtained from 1,1,1 is converted into the first LPF1, second LPF1, second LPF2, and second LPF of each filter circuit.
F3, BPF1, BPF2, and BPF3, the bounce component signal a, the pitch component signal a ', the roll component signal a "of the sprung vertical acceleration gg, and the sprung vertical velocity vv
This is a step of performing processing for obtaining a bounce component signal v, a pitch component signal v ′, and a roll component signal v ″.

In step 103, a bounce component, a pitch component, and a bounce component are determined according to the vehicle speed VV based on the map shown in FIG.
Proportional constant of each correction component added to the roll component
This is a step of setting A _f , A _r , B _f , B _r , C _f , and _Cr . FIG. 17 is a map for the front wheel, and the map for the rear wheel is obtained based on the same map.

Step 104 uses the following equation (1).
Based on the component signals a, a ′, a ″, v, v ′, v ″ and the proportional constants A _f , A _r , B _f , B _r , C _f , and C _r , the control signal V ( V ₁ , V ₂ , V ₃ , V ₄ ).

[0032]

(Equation 1) Note that α _f , β _f , B _f , γ _f , and C _f are the respective proportional constants α _r , β _r , B _r , γ _r , and C _r of the front wheels are the respective proportional constants a ₁ , a _{1 of the} rear wheels. ', A ₁ ″: front wheel right sprung vertical acceleration signal a ₂ , a ₂ ′, a ₂ ″: front wheel left sprung vertical acceleration signal a ₃ , a ₃ ′, a ₃ ″: rear wheel right sprung Vertical acceleration signal a ₄ , a ₄ ′, a ₄ ″: rear wheel left sprung vertical acceleration signal v ₁ , v ₁ ′, v ₁ ″: front wheel right sprung vertical speed signal v ₂ , v ₂ ′, v ₂ ": front left sprung mass vertical velocity signal _{v 3, v 3 ', v} 3": rear wheel on the right of the spring vertical velocity signal _{v 4, v 4', v} 4 ": sprung mass vertical speed of the rear wheel left Signal.

In each equation, the part bounded by the first α _f and α _r is the bounce rate, and β _f and β _r
The portion between the two is the pitch rate, γ _f , γ _r
The rolled part is the roll rate. Note that each rate contains a respective correction component. Thus, the bounce component,
A pitch component and a roll component are determined, and a portion for determining these components in the upper and lower G sensor 1 and the control unit 4 constitutes a bounce component detector, a pitch component detector, and a roll component detector in the claims. .

[0034] Step 105, the control signal V is a step equal to or larger than a predetermined threshold value [delta] _T, the process proceeds to step 106 in YES, a step 1 is NO
Proceed to 07.

Step 106 is a step of the shock absorber S
This is a step of controlling A to the extension-side hard area HS.

[0036] Step 107 is a step of determining whether a value between the control signal V is a predetermined threshold value [delta] _T and the threshold - [delta _C, the process proceeds to step 108 YES, a by NO Proceed to step 109.

Step 108 is a step of shock absorber S
This is the step of controlling A to the soft area SS.

[0038] Step 109 is a step of displaying convenience, if the result of determination is NO in step 105 and step 107, the control signal V is less than a predetermined threshold value - [delta _C, in this case, Go to step 108.

Step 110 is the shock absorber S
This is a step of controlling A to the compression side hard area SH.

Next, the operation of the embodiment will be described with reference to the time chart of FIG.

When the sprung vertical velocity changes as shown by the control signal V in this figure, as shown in the figure, the control signal V
Is between the predetermined threshold values δ _T and −δ _C , the shock absorber SA is controlled to the soft region SS.

When the control signal V exceeds the threshold value δ _{T, the} compression side is controlled to the expansion side hard region HS to fix the compression side to a low attenuation characteristic, while making the expansion side attenuation characteristic proportional to the control signal V. Change. At this time, the attenuation characteristic C is C = kV
Is controlled so that

When the control signal V becomes equal to or less than the threshold value -δ _{C, the} compression side is controlled to the compression side hard area SH to fix the extension side to the low attenuation characteristic, while making the compression side attenuation characteristic proportional to the control signal V. Change. Also at this time, the attenuation characteristic C is C = k
・ V is controlled to be V.

In the first embodiment described above, the following effects can be obtained.

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

A correction is made to increase the value of the proportional constant multiplied by the correction component as the vehicle speed increases. By changing the proportional constant, a lower damping characteristic based on the lower proportional constant at a low vehicle speed is obtained. The ride comfort of the vehicle can be ensured, and at a high vehicle speed, the steering stability of the vehicle can be ensured by a high damping characteristic based on a high proportional constant. In addition, by setting a large change rate of the proportional constant with respect to the vehicle speed multiplied by the correction component of the roll rate, sufficient system responsiveness can be obtained even for roll damping in a sudden lane change during high-speed driving. As a result, steering stability can be ensured.

The correction component based on the sprung vertical acceleration increases as the vibration frequency of the vehicle body increases, and the phase is always advanced for each component based on the sprung vertical speed. The nature becomes high.

In performing the above control,
Since only the upper and lower G sensor 1 and the vehicle speed sensor 5 are used as the detecting means, the number of parts can be reduced, the cost can be reduced, and the labor and space for assembling and the weight can be reduced.

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

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

(Second Embodiment) In the second embodiment, when the pulse motor 3 is driven as a shock absorber SA of a variable damping characteristic type, as shown in FIG. , Both of which have a known structure that changes from high attenuation to low attenuation (for example, Japanese Utility Model Application Laid-Open No. 63-112914).
No. public relations).

In the third embodiment, as shown in FIG. 20, load sensors (sprung-spring-unsprung relative speed detecting means) 6, 6, 6, and 6 are provided as input means. As shown in FIG. 18, the load sensor 6 is provided on the piston rod 7 at a position below the mounting portion of the shock absorber SA to the vehicle body, and a damping force (relative force) generated by the shock absorber SA is provided. (Equivalent to speed) F
Is detected as a load.

Control unit 300 of the second embodiment
21 will be described with reference to the flowchart of FIG. 21. In step 301, the damping force F detected by the load sensor 6 is determined.
After this processing, the process goes through steps 101 to 104 similar to those in the first embodiment, and then proceeds to step 302.

In step 302, the damping force F and the control signal V
Is a step for determining whether or not
The process proceeds to step 303 with NO, and proceeds to step 304 with NO (with a different sign).

In step 303, the damping force F becomes F = k
The attenuation characteristic is changed so as to be V.

In step 304, the damping characteristics of the shock absorber SA are controlled so that both the extension and the pressure have the lowest damping characteristics.

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

For example, in the embodiment, the pitch component is
The difference between the front and rear sprung vertical speeds is obtained, and the roll component is obtained from the difference between the left and right sprung vertical speeds. A sensor that detects a change in pitch angle, such as a gyro sensor, or a change in roll angle is detected. A sensor may be used.

[0059]

As described above, in the vehicle suspension system of the present invention, the bounce rate, the pitch rate, and the roll obtained by multiplying the bounce component, the pitch component, and the roll component by a predetermined proportionality constant by the damping characteristic control means. A shock absorber based on a control signal obtained by a rate and a correction component obtained by multiplying a predetermined proportional constant based on a sprung vertical acceleration applied to at least one of the bounce component, the pitch component, and the roll component. Since the damping characteristic is controlled, not only bounce but also pitch,
Sufficient control force is obtained for the rolls, thereby providing the effect of improving ride comfort and steering stability.

The correction component based on the sprung vertical acceleration increases as the vibration frequency of the vehicle body increases, and the phase always advances with respect to the sprung vertical speed. The effect that the property can be improved is acquired.

Further, since the proportional constant correction unit adds a correction to increase the value of the proportional constant multiplied by the correction component as the vehicle speed increases, at a low vehicle speed, a lower damping characteristic based on a lower proportional constant is applied. The ride comfort of the vehicle can be ensured, and at the time of high vehicle speed, there is an effect that the steering stability of the vehicle can be ensured by a high damping characteristic based on a high proportionality constant.

[Brief description of the drawings]

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

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

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

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

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

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

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

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

FIG. 9 is a perspective view of the shock absorber shown in FIG.
It is a -M sectional view.

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

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

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

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

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

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

FIG. 16 is a time chart showing the operation of the first embodiment.

FIG. 17 is a proportional component characteristic map for a correction component with respect to the vehicle speed stored in the control unit in the first embodiment.

FIG. 18 is a sectional view showing a shock absorber applied to the device of the second embodiment.

FIG. 19 is a characteristic diagram of a damping characteristic of a shock absorber of the device of the second embodiment.

FIG. 20 is a system block diagram illustrating a device according to a second embodiment.

FIG. 21 is a flowchart showing a control operation of a control unit of the second embodiment.

[Explanation of symbols]

 a damping characteristic changing means b shock absorber c sprung vertical acceleration detecting means d sprung vertical speed detecting means e bounce component detecting means f pitch component detecting means g roll component detecting means h vehicle speed detecting means j damping characteristic controlling means k proportional constant correction Department

Claims (6)

(57) [Claims] 1. A shock absorber interposed between a vehicle body side and each wheel side and capable of changing damping characteristics by damping characteristic changing means, and detecting a sprung vertical acceleration near a position where each shock absorber is provided. Sprung vertical acceleration detecting means, sprung vertical speed detecting means for detecting a sprung vertical velocity near a position where each shock absorber is provided, bounce component detecting means for detecting a bouncing component of the vehicle body, and a pitch of the vehicle body Pitch component detecting means for detecting the component, roll component detecting means for detecting the roll component of the vehicle body, vehicle speed detecting means for detecting the vehicle speed, and the damping characteristics of each shock absorber are determined for the bounce component, the pitch component and the roll component. Bounce rate, pitch rate, and roll rate obtained by multiplying by the proportional constant of
Damping characteristic control means for controlling based on a control signal obtained from a correction component obtained by multiplying a predetermined proportionality constant based on a sprung vertical acceleration applied to at least one of the bounce component, the pitch component and the roll component And a proportional constant correction unit provided in the damping characteristic control means and increasing a proportional constant multiplied by the sprung vertical acceleration as the vehicle speed increases. 2. The roll component detecting means according to claim 2, wherein said pitch component detecting means is means for detecting a pitch component from a sprung vertical speed difference between the front and rear of the vehicle body based on a sprung vertical speed detected by said sprung vertical speed detecting means. 2. A vehicle suspension system according to claim 1, wherein said means comprises means for detecting a roll component from a difference between left and right sprung vertical speeds of the vehicle body based on a sprung vertical speed detected by said sprung vertical speed detecting means. 3. A sprung component detected by the sprung vertical acceleration detecting means, based on a sprung vertical acceleration detected by the sprung vertical acceleration detecting means, to obtain a correction component of a pitch component from a sprung vertical acceleration difference between the front and rear of the vehicle body. 3. The vehicle suspension device according to claim 1, wherein a correction component of a roll component is obtained from a difference between a sprung vertical acceleration of the right and left sides of the vehicle body based on the vertical acceleration. 4. A compression-side hard region in which the expansion side has a variable attenuation characteristic and the compression side is fixed to a low attenuation characteristic, a compression-side hard region in which the compression side has a variable attenuation characteristic and the expansion side is fixed to a low attenuation characteristic. The damping characteristic control means is formed in a structure having a soft region having low damping characteristics on both the side and the pressure side, and the damping characteristic control means controls the shock absorber in the extension side hard region when the control signal is equal to or more than a positive threshold value. When the control signal is equal to or less than the negative threshold, the shock absorber is controlled in the pressure side hard region, and when the control signal is between the positive and negative thresholds, the shock absorber is controlled in the soft region. The vehicle suspension according to claim 1, 2 or 3, wherein: 5. A bounce component and a correction component added to the bounce component for obtaining the control signal,
Using a signal passed through a band-pass filter including a sprung resonance frequency in each of the front and rear wheels, a pitch component and a correction component added to the pitch component are determined using a signal passed through a band-pass filter including a pitch resonance frequency, and a roll component and 5. The vehicle suspension according to claim 1, wherein a signal passed through a band-pass filter including a roll resonance frequency is used as the correction component added to the roll component. 6. The control signal is obtained by adding a first proportional constant to a bounce component to which a correction component is added, a second proportional constant to a pitch component to which a correction component is added, and a correction component. Third proportional constants to be multiplied by the obtained roll components are set independently of each other, the first proportional constant is a numerical value according to the vertical spring constant, and the second proportional constant is a numerical value according to the pitch rigidity,
6. The vehicle suspension according to claim 1, wherein the third proportional constant is a numerical value corresponding to the roll rigidity.