JPH05319057A - Vehicle suspension device - Google Patents

Abstract

PURPOSE:To even to inertia moment, vehicle operation stability is improved, and control responsiveness to high-frequency input is enhanced while assuring vehicle comfortableness. CONSTITUTION:A damping characteristic control means j is provided to control the damping characteristic of each shock absorber b based on a control signal obtained from a bounce rate, pitch rate, and roll rate obtained by multiplying a bounce component, pitch component, and roll component by the predetermined proportional constant, and a correction component obtained by multiplying the predetermined proportional constant based on sprung acceleration added to any one of the bounce component, pitch component, and roll component. A proportional constant correcting part k is provided in the damping characteristic control means j to increase the proportional constant multiplied into the sprung vertical acceleration with car speed increased.

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 characteristics of a shock absorber.

[0002]

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

This conventional vehicle suspension system detects the sprung vertical speed and the relative speed between the sprung and unsprung parts, and when both have the same sign, the damping characteristic is made hard, and when the two have different signs, the damping characteristic is made. The damping characteristic control such as softening was performed independently for the four wheels.

[0004]

However, since the above-mentioned conventional apparatus has the above-mentioned structure, when the characteristics of the hardware are suitable when the vehicle body is moving in the bounce direction, With respect to the body movement in which bounce and pitching are coupled, a moment of inertia of the body around the center of gravity of the body is added to the sprung mass, so the damping force (control force) is insufficient and the steering stability is poor. There was a point.

Further, since the sprung vertical velocity signal causes a phase shift (delay) with respect to the vehicle behavior, there is a problem that the control response is deteriorated particularly for high frequency input.

The present invention has been made by paying attention to the above-mentioned conventional problems, and it is possible to secure a comfortable ride of the vehicle and to obtain a sufficient vibration damping property with respect to the moment of inertia to stabilize the steering of the vehicle. It is an object of the present invention to provide a vehicle suspension device capable of improving the controllability with respect to a high-frequency input while improving the performance.

[0007]

In order to achieve the above object, the vehicle suspension system according to claim 1 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 sprung vertical acceleration detecting means c for detecting sprung vertical acceleration in the vicinity of the position where each shock absorber b is provided, and each shock absorber b
The sprung vertical velocity detecting means d for detecting the sprung vertical velocity in the vicinity of the position, the bounce component detecting means e for detecting the bounce component of the vehicle body, and the pitch component detecting means f for detecting the pitch component of the vehicle body. The roll component detecting means g for detecting the roll component of the vehicle body, the vehicle speed detecting means h for detecting the vehicle speed, and the damping characteristics of each shock absorber b.
Bounce rate, pitch rate, roll rate obtained by multiplying the bounce component, pitch component, and roll component by a predetermined proportional constant, and sprung vertical acceleration applied to at least one of the bounce component, pitch component, and 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
And a proportional constant correction unit k for increasing the proportional constant multiplied by the sprung vertical acceleration as the vehicle speed increases.

A vehicle suspension system according to a second aspect of the invention is provided with a shock absorber b interposed between the vehicle body side and each wheel side, the damping characteristic of which can be changed by the damping characteristic changing means a, and each shock absorber b. Sprung vertical acceleration detecting means c for detecting sprung vertical acceleration near the position, sprung vertical speed detecting means d for detecting sprung vertical speed near the position where each shock absorber b is provided, and each shock A relative speed detecting means m for detecting a relative speed between the sprung portion and the unsprung portion in the vicinity of the position where the absorber b is provided;
Bounce component detecting means e for detecting the bounce component of the vehicle body
And a pitch component detecting means f for detecting the pitch component of the vehicle body.
And a roll component detecting means g for detecting the roll component of the vehicle body
A vehicle speed detecting means h for detecting a vehicle speed, 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 bounce component, pitch component, and roll component 1
The control signal is calculated from the correction component obtained by multiplying the sprung vertical acceleration by a predetermined proportional constant, and the damping characteristic is obtained when this control signal and the relative speed between the sprung and unsprung parts have the same sign. On the other hand, a damping characteristic control means j for controlling the damping characteristic to a minimum when the sign is different and a proportional constant for multiplying the sprung vertical acceleration as the vehicle speed increases, provided in the damping characteristic control means j. And a constant correction unit k.

Incidentally, the pitch component detecting means is 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, and the roll component detecting means. May be means for detecting the roll component from the difference between the sprung vertical speeds on the left and right of the vehicle body based on the sprung vertical speed detected by the sprung vertical speed detecting means.

A sprung vertical acceleration detecting means detects a pitch component correction component from a sprung vertical acceleration difference between the front and rear of the vehicle body based on the sprung vertical acceleration detected by the sprung vertical acceleration detecting means. A correction component of the roll component may be obtained from the difference between the sprung vertical accelerations on the left and right of the vehicle body based on the vertical acceleration.

Further, the shock absorber includes an expansion side hard region in which the expansion side is variable in damping characteristic and the compression side is fixed in low damping characteristic, and a compression side hard region in which compression side is variable in damping side and expansion side is fixed in low damping characteristic is expanded. The damping characteristic control means is formed in a structure having three regions, a soft region having a low damping characteristic on both the compression side and the compression side, and the shock absorber is controlled in the expansion hard region when the control signal is a positive threshold value or more. If the control signal is below the negative threshold value, the shock absorber is controlled in the pressure side hard area, and if the control signal is between the positive and negative threshold values, the shock absorber is controlled in the soft area. Good. Further, in obtaining the control signal, the bounce component and the correction component added to the bounce component are signals that have passed through a bandpass filter including the sprung resonance frequencies of the front and rear wheels, respectively, and the correction added to the pitch component and the pitch component. The component uses a signal that has passed through a bandpass filter including the pitch resonance frequency,
The roll component and the correction component added to the roll component are
A band-pass filtered signal containing the roll resonance frequency may be used.

Further, in obtaining the control signal,
A first proportional constant for multiplying the bounce component to which the correction component is added, and a second constant to the pitch component to which the correction component is added
And a third proportionality constant for multiplying the roll component to which the correction component is added are independently set, and the first proportionality constant is a numerical value according to the vertical spring constant,
The proportional constant of 1 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 sprung velocity detection means, the bounce component detection means, the pitch component detection means, and the roll component detection means enable vertical movement (bouncing) on the spring, pitching,
When the roll is detected, the damping characteristic control means, the bounce rate, the pitch rate, and the roll rate obtained by multiplying the bounce component, the pitch component, and the roll component by a predetermined proportional constant, the bounce component, the pitch component, and the roll component. A control signal is obtained from a correction component obtained by multiplying at least one of the sprung vertical accelerations by a predetermined proportional constant, and the damping characteristic of each shock absorber is controlled according to this control signal.

Therefore, not only the bounce but also the pitch and the roll can be sufficiently controlled, and the steering stability of the vehicle can be secured.

Further, the proportional constant correction unit adds a correction for increasing the value of the proportional constant multiplied by the correction component as the vehicle speed increases. By changing the proportional constant, the proportional constant is set to be low at low vehicle speed. The ride quality of the vehicle can be ensured by the low damping characteristic based on the proportional constant, and the steering stability of the vehicle can be secured by the high damping characteristic based on the high proportional constant at high vehicle speed.

Further, the correction component based on the sprung vertical acceleration has a larger value 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 velocity. The control response to high frequency input becomes high.

Further, in the apparatus according to the second aspect, the damping characteristic control means increases the damping characteristic when the control signal and the sprung / unsprung relative speed have the same sign, while the both have different signs. In this case, the attenuation characteristic is minimized. In this case as well, sufficient control force is obtained not only for bounce, but also for pitch and roll, and the ride comfort of the vehicle at low vehicle speeds is ensured while the steering stability of the vehicle at high vehicle speeds is secured. In addition, the control response to a high frequency input becomes high.

[0018]

Embodiments of the present invention will be described with reference to the drawings. (First Embodiment) First, the structure 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 described in claims 1, 3, 4, 5, 6, 7 and is a vehicle body and four wheels. Is interposed between the four shock absorbers SA ₁ , SA ₂ , S
A ₃ and SA ₄ (in the explanation of the shock absorber, these are simply referred to as SA when referring to these four collectively and when describing their common configuration) are provided. A vertical acceleration sensor (hereinafter referred to as vertical G sensor) 1 for detecting sprung vertical acceleration is provided on the vehicle body in the vicinity of each shock absorber SA.
Is provided. In addition, the signals from the respective sensors 1 are input to the positions near the driver's seat so that the shock absorbers S
A control unit 4 that outputs a drive control signal to the A pulse motor 3 is provided.

FIG. 3 is a system block diagram showing the above-mentioned configuration. The control unit 4 is provided with 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. 14 is provided for each upper and lower G sensor 1. That is, the first LPF is a low-pass filter circuit for removing noise in the high frequency range (30 Hz or higher) from the signals sent from the upper and lower G sensors 1. B
The PF 1 passes the frequency range including the sprung resonance frequency to pass the sprung vertical acceleration bounce component signal a (a ₁ , a
₂ , a ₃ , a _{4 In} addition, the numbers ₁ , ₂ , ₃ , ₄ correspond to the positions of the shock absorbers SA. The same applies to the following. ) Is a band pass filter circuit that forms BP
F2 is a pitch component signal a ′ (a ₁ ′, a _{1) of the} sprung vertical acceleration that passes through a frequency range including the pitch resonance frequency.
₂ ', a _3', a band-pass filter circuit for forming a a ₄ '). The BPF ₃ is a bandpass filter circuit that passes a frequency range including a roll resonance frequency and forms a roll component signal a ″ (a ₁ ″, a ₂ ″, a ₃ ″, a ₄ ″) of sprung vertical acceleration. The second LPF 1 integrates the bounce component signal a of the sprung vertical acceleration that has passed through the bandpass filter circuit BPF 1 and integrates the sprung vertical velocity bounce component signal v (v ₁ , v ₂ , v ₃ , v ₄₎
The numbers ₁ , ₂ , ₃ , and ₄ correspond to the positions of the shock absorbers SA. The same applies to the following. ) Is a low-pass filter circuit for converting to. The second LPF 2 integrates the pitch component signal a ′ of the sprung vertical acceleration that has passed through the bandpass filter circuit BPF 2 and integrates the sprung vertical velocity pitch component signal v ′ (v ₁ ′, v ₂ ′, v ₃ ′, v ₄ ') is a low-pass filter circuit for conversion. Second LPF
Reference numeral 3 integrates the roll component signal a ″ of the sprung vertical acceleration that has passed through the bandpass filter circuit BPF3 to obtain the roll component signal v ″ (v ₁ ″, v ₂ ″, v) of the sprung vertical velocity.
₃ ", v _4" is a low-pass filter circuit for converting). By the way, in the present embodiment, the sprung resonance, the pitch resonance, and the roll resonance have different frequencies, but when these resonance frequencies are similar,
The band pass filter and the second low pass filter are BP
Only the F1 and the second LPF1 are required.

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

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 that 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
An expansion side second flow path E reaching the lower chamber B by opening the outer peripheral side of the expansion side damping valve 12 via the third and fourth ports 14;
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, the bypass flow path G, which leads to the lower chamber B via the. 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 compression-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 is constructed so that the damping characteristics can be changed in multiple steps by rotating the adjuster 40 with the characteristics shown in FIG. 6 on both the expansion side and the compression side. That is, as shown in FIG. 7, both the expansion side and the compression side are in the soft state (hereinafter, the soft region S
When the adjuster 40 is rotated counterclockwise from (S), the damping characteristic can be changed in multiple steps only on the extension side, and the compression side becomes a region where the low damping characteristic is fixed (hereinafter referred to as the extension side hard region HS). On the contrary, when the adjuster 40 is rotated clockwise, the damping characteristic can be changed in multiple steps only on the compression side, and the extension side becomes a region where the low damping property is fixed (hereinafter referred to as the compression side hard region SH). There is.

By the way, in FIG. 7, when the adjuster 40 is arranged at the positions of, the KK cross section, the MM cross section, and the NN cross section in FIG. 5, respectively, are shown in FIGS. 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.

In step 101, each vertical G sensor 1,
Vertical acceleration gg and vehicle speed VV are read from 1, 1, 1 and vehicle speed sensor 5.

In step 102, the upper and lower G sensors 1,
The vertical acceleration gg obtained from 1, 1, 1 is used for each filter circuit 1st LPF1, 2nd LPF1, 2nd LPF2, 2nd LP
F3, BPF1, BPF2, BPF3 are processed to generate 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.
Of the bounce component signal v, the pitch component signal v ′, and the roll component signal v ″.

In step 103, based on the map shown in FIG. 17, bounce component, pitch component,
Proportional constant of each correction component added to the roll component
This is the step of setting A _f , A _r , B _f , B _r , C _f , and C _r . Note that FIG. 17 is a map on the front wheel side, and the rear wheel side is also 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 , C _r , the control signal V ( This is a step of calculating 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 proportional constants α _r , β _r , B _r , γ _r , and C _r of the front wheels, and proportional constants a ₁ and a _{1 of the} rear wheel. ', A ₁ ″: Vertical sprung acceleration signal on the right front wheel a ₂ , a ₂ ′, a ₂ ″: Vertical sprung acceleration signal on the left front wheel a ₃ , a ₃ ′, a ₃ ″: Sprung on the right rear wheel Vertical acceleration signal a ₄ , a ₄ ′, a ₄ ″: Vertical spring acceleration signal on the left of the rear wheel v ₁ , v ₁ ′, v ₁ ″: Vertical velocity signal on the right spring of the front wheel 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 It is a signal.

In each equation, the first part bounded by α _f and α _r is the bounce rate, and β _f and β _r
The part enclosed by is the pitch rate, and γ _f and γ _r
The part marked with is the roll rate. It should be noted that each rate includes each correction component. Thus, the signals from the upper and lower G sensors 1 cause the bounce component,
The pitch component and the roll component are obtained, and the parts of the upper and lower G sensors 1 and the control unit 4 that obtain them constitute the bounce component detection means, the pitch component detection means, and the roll component detection means. ..

Step 105 is a step of judging whether or not the control signal V is equal to or more than a predetermined threshold value δ _T , and if YES, the routine proceeds to step 106, and if NO, step 1
Proceed to 07.

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

Step 107 is a step of judging whether or not the control signal V is a value between a predetermined threshold value δ _T and a threshold value −δ _{C. If} YES, then the routine proceeds to step 108, and if NO. Go to step 109.

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

Step 109 is a step which is displayed for the sake of convenience. When NO is determined in steps 105 and 107, the control signal V is below a predetermined threshold value -δ _C , and in this case, Go to step 108.

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

Next, the operation of the embodiment apparatus 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 a value between the predetermined thresholds δ _T and −δ _C , the shock absorber SA is controlled in the soft region SS.

When the control signal V becomes equal to or higher than the threshold value δ _T , the expansion side hard region HS is controlled to fix the compression side to the low damping characteristic, while the expansion side damping characteristic is made proportional to the control signal V. To change. At this time, the attenuation characteristic C is C = kV
Control so that

When the control signal V becomes equal to or lower than the threshold value -δ _{C, the} compression side hard region SH is controlled to fix the extension side to a low damping characteristic, while making the compression side damping characteristic proportional to the control signal V. To change. Also at this time, the damping characteristic C is C = k.
・ It is controlled so that it becomes V.

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

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

Correction is added to increase the value of the proportional constant multiplied by the correction component as the vehicle speed increases. By changing this proportional constant, a low damping characteristic based on a lower proportional constant is obtained at low vehicle speed. The ride comfort of the vehicle can be ensured, and the steering stability of the vehicle can be ensured at high vehicle speed by the high damping characteristic based on the high proportional constant. In addition, especially by setting a large rate of change of the proportional constant multiplied by the correction component of the roll rate with respect to the vehicle speed, sufficient system responsiveness can be obtained even for roll vibration suppression during sudden lane changes during high speed running. It is possible to secure the steering stability.

The correction component based on the sprung vertical acceleration has a larger value 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 velocity. Will be more likely.

In performing the above control,
Since only the vertical G sensor 1 and the vehicle speed sensor 5 are used as the detecting means, the number of parts can be reduced to reduce the cost, and the assembling labor, the assembling space, 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, each rate can be accurately detected based on the sprung vertical velocity even when the sprung resonance frequency, the pitch resonance frequency, and the roll resonance frequency are different in the vehicle.

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

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

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

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

In step 302, the damping force F and the control signal V
YES in the step of determining whether and are the same sign
Then, the process proceeds to step 303, and if NO (different sign), the process proceeds to step 304.

In step 303, the damping force F is F = k
The attenuation characteristic is changed so that it becomes V.

In step 304, the damping characteristic of the shock absorber SA is controlled so that both the extension and the compression have the minimum damping characteristic.

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, in the embodiment, the pitch component is
Although it was determined by the difference between the front and rear sprung vertical velocities, and the roll component was calculated from the difference between the left and right sprung vertical velocities, a sensor that detects pitch angle changes such as a gyro sensor or roll angle change You may use the sensor which does.

[0059]

As described above, in the vehicle suspension system of the present invention, the bounce rate, pitch rate, and roll obtained by multiplying the bounce component, pitch component, and roll component by a predetermined proportional constant by the damping characteristic control means. Of the shock absorber based on the control signal obtained from the rate and the correction component obtained by multiplying the sprung vertical acceleration applied to at least one of the bounce component, the pitch component and the roll component by a predetermined proportional constant. Since the damping characteristic is controlled, not only the bounce but also the pitch,
Sufficient control force can be obtained for the roll as well, which has the effect of improving riding comfort and steering stability.

Further, the correction component based on the sprung vertical acceleration has a larger value as the vibration frequency of the vehicle body is higher, and the phase is always advanced with respect to the sprung vertical speed. It is possible to obtain the effect of enhancing the sex.

Further, since the proportional constant correction unit adds a correction for increasing 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 the lower proportional constant is applied. The ride comfort of the vehicle can be ensured, and the steering stability of the vehicle can be ensured by the high damping characteristic based on the high proportional constant at high vehicle speed.

[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 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 characteristic diagram of damping characteristics corresponding to the step position of the pulse motor of the shock absorber.

FIG. 8 is a part of the shock absorber shown in FIG.
FIG.

FIG. 9 is an M of FIG. 5 showing a main part of the shock absorber.
FIG.

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 pressure side hard state.

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

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

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

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

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 damping characteristics of the shock absorber of the second embodiment device.

FIG. 20 is a system block diagram showing a second embodiment device.

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

[Explanation of symbols]

 a damping characteristic changing means b shock absorber c sprung vertical acceleration detecting means d sprung vertical velocity 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)

[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, and a sprung vertical acceleration near the position where each shock absorber is provided is detected. The sprung vertical acceleration detection means, the sprung vertical speed detection means for detecting the sprung vertical speed near the position where each shock absorber is provided, the bounce component detection means for detecting the bounce component of the vehicle body, and the 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 damping characteristics of each shock absorber are specified for the bounce component, pitch component and roll component. Bounce rate, pitch rate, and roll rate, which are obtained by multiplying by the proportional constant of
Damping characteristic control means for controlling based on a control signal obtained by a correction component obtained by multiplying a sprung vertical acceleration applied to at least one of the bounce component, the pitch component and the roll component by a predetermined proportional constant. And a proportional constant correction unit which is provided in the damping characteristic control means and which increases a proportional constant for multiplying the sprung vertical acceleration as the vehicle speed increases, the vehicle suspension device. 2. The 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 the sprung vertical speed detected by the sprung vertical speed detecting means, and the roll component detecting means. 2. The vehicle suspension system according to claim 1, wherein said means is means for detecting a roll component from a difference between sprung vertical speeds on the left and right of the vehicle body based on a sprung vertical speed detected by said sprung vertical speed detecting means. 3. A sprung vertical acceleration detection means detects a pitch component correction component from a sprung vertical acceleration difference between the front and rear of a vehicle body based on a sprung vertical acceleration detected by the sprung vertical acceleration detection means, and a sprung vertical acceleration detection means detects the sprung vertical acceleration. 3. The vehicle suspension device according to claim 1, wherein the correction component of the roll component is obtained from the difference between the vertical accelerations on the left and right of the vehicle body based on the vertical acceleration. 4. The shock absorber includes an expansion side hard region in which the expansion side is variable in damping characteristic and the compression side is fixed in low damping characteristic, and a compression side hard region in which the compression side is variable in damping characteristic and expansion side is fixed in low damping characteristic is expanded. The damping characteristic control means is formed in a structure having three regions, a soft region having a low damping characteristic on both the side and the compression side, and the shock absorber is controlled in the hard region at the extending side when the control signal is equal to or more than a positive threshold value. The shock absorber is controlled in the pressure side hard area when the control signal is below the negative threshold value, and the shock absorber is controlled in the soft area when the control signal is between the positive and negative threshold values. The vehicle suspension system according to claim 1, 2 or 3. 5. A bounce component and a correction component added to the bounce component in obtaining the control signal are:
The signal that has passed through the bandpass filter including the sprung resonance frequency in each of the front and rear wheels is used, and the pitch component and the correction component added to the pitch component use the signal that passes through the bandpass filter that includes the pitch resonance frequency, and the roll component and The vehicle suspension system according to claim 1, 2, 3 or 4, wherein the correction component added to the roll component uses a signal that has passed through a bandpass filter including a roll resonance frequency. 6. When obtaining the control signal, a first proportionality constant for multiplying a bounce component to which a correction component is added, a second proportionality constant to a pitch component to which a correction component is added, and a correction component are added. The third proportional constant to be multiplied by the roll component is set independently, the first proportional constant is a numerical value according to the vertical spring constant, the second proportional constant is a numerical value according to the pitch rigidity,
6. The vehicle suspension device according to claim 1, wherein the third constant of proportionality is a numerical value according to roll rigidity.