JP3124633B2 - 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 the sprung vertical speed and the relative speed between the sprung and unsprung, and when both have the same sign, the damping characteristic is made hard, and when both have different signs, the damping characteristic is made soft. The control of the damping characteristics based on the skyhook theory is performed independently for four wheels.

[0003]

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, In addition to the bouncing, for the body motion coupled with the pitch and roll, the body moment of inertia around the center of gravity of the center of the body is added to the sprung mass,
There is a problem that the damping force (control force) is insufficient and the steering stability is poor.

Further, in the damping characteristic control based on the skyhook theory, it is necessary to switch the damping characteristic by driving the actuator every time the sign of the two signs of the sprung vertical speed and the relative speed is switched. Therefore, there has been a problem that control responsiveness is deteriorated, and the number of times of driving of the actuator is increased, thereby reducing durability.

[0005] The present invention has been made in view of the conventional problems described above, it is possible to improve the steering stability sufficient damping property is obtained for the moment of inertia,
The purpose is to improve the control response and the durability of the actuator.

[0006]

In order to achieve the above object, a vehicle suspension system according to the first aspect of the present invention, as shown in the claim correspondence diagram of FIG. A shock absorber b which is interposed and whose damping characteristic can be changed by the damping characteristic changing means a; a sprung vertical speed detecting means c which detects a sprung vertical speed near a position where each shock absorber b is provided; Lateral acceleration detecting means d for detecting a rate of change in lateral acceleration, and a damping characteristic of each shock absorber b, a bounce rate based on a sprung vertical speed and a pitch rate detected from a sprung vertical speed difference between front and rear of the vehicle and a lateral direction. and a damping characteristic control means e for controlling on the basis of a control signal obtained by the roll rate based on the acceleration rate of change, the shock absorber, the extension side
Extension side hardware area with variable damping characteristics and fixed pressure side with low damping characteristics
Range and the compression side are variable attenuation characteristics, and the extension side is fixed to low attenuation characteristics.
Compression hard area and soft with low damping characteristics on both extension and compression sides
And a region having three regions,
The shock control when the control signal has a positive value.
When the control signal is a negative value
Controls and controls the shock absorber in the pressure-side hard area
When the signal is 0, the shock absorber is controlled to the soft area.
It was configured so that:

[0007]

[0008]

When the bounce, pitch, and roll are detected by the sprung vertical speed detecting means and the lateral acceleration detecting means, the damping characteristic control means obtains a control signal based on the bounce rate, the pitch rate, and the roll rate. The damping characteristic of the shock absorber is controlled according to the signal. Therefore, a sufficient control force can be obtained not only for bounce but also for pitch and roll.

Further, control of the shock absorber when the control signal has a positive value and controlled by extension phase hard region (compression phase is fixed to a low damping characteristics), and the compression side hard region shock absorber when the control signal is negative ( When the control signal is 0, the shock absorber is controlled in the soft range. Therefore, the control signal based on the sprung vertical speed and the sprung / unsprung force are controlled. When the relative speed of the shock absorber is the same, the stroke side of the shock absorber at that time is controlled to the hard characteristic, and when the relative speed is different, the stroke side of the shock absorber at the time is controlled to the soft characteristic. The same control as that based on damping characteristics can be performed without detecting the relative speed between the sprung and unsprung portions, and the switching of the damping characteristics in the direction of the low damping characteristics is performed by the actuator. Since the driving is performed without driving, the frequency of switching of the damping characteristic is reduced as compared with the damping characteristic control based on the conventional skyhook theory, so that the control response and the durability of the actuator can be improved. .

[0010]

An embodiment of the present invention will be described with reference to the drawings. (First Embodiment) First, the configuration will be described. FIG.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a structural explanatory view showing a vehicle suspension system according to a first embodiment of the present invention, wherein four shock absorbers SA ₁ , SA ₂ , SA ₃ , SA ₄ (besides shocks) are interposed between a vehicle body and four wheels. In explaining the absorber, these 4
When referring to one collectively and when describing these common configurations, they are simply denoted by SA. ) Is provided. A vertical acceleration sensor (hereinafter, referred to as a vertical G sensor) 1 for detecting vertical acceleration is provided on the vehicle body in the vicinity of each shock absorber SA. A lateral acceleration sensor (hereinafter, referred to as a lateral G sensor) 2 for detecting directional acceleration is provided. Signals from the upper and lower G sensors 1 are input to the vicinity of the driver's seat, and the signals from the respective shock absorbers SA are input.
A control unit 4 for outputting a drive control signal to the 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 interface circuit 4a includes the above-described upper and lower G sensors 1 and A signal from the lateral G sensor 2 is input. In the interface circuit 4a, one set of four filter circuits shown in FIG. That is, the LPF 1 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. LPF2 is a low-pass filter circuit for integrating a signal indicating acceleration that has passed through low-pass filter circuit LPF1 and converting the signal into a sprung vertical velocity. The BPF ₁ passes the frequency range including the sprung resonance frequency and passes through the bounce component signal v (v ₁ , v
₂ , v3, _v4 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 range including the pitch resonance frequency to pass pitch component signals v ′ (v ₁ ′, v ₂ ′, v ₃ ′, v
₄ ') is a bandpass filter circuit. By the way, in the present embodiment, the case where the sprung resonance and the pitch resonance have different frequencies is taken as an example. However, when the two resonance frequencies are close to each other, the bandpass filter of FIG.
Only PF1 may be used. The interface circuit 4
As shown in FIG. 15, a set of two filter circuits for processing a signal sent from the lateral G sensor 2 is provided in a. That is, the HPF 1 differentiates the signal indicating the lateral acceleration sent from the lateral G sensor 2 and converts the signal into a rate of change in lateral acceleration (lateral jerk) to thereby obtain the roll component signal G.
_This is a high-pass filter circuit for forming _G. LP
F3 is a phase delay caused by passing through the high-pass filter circuit HPF1 (45 degrees near the roll resonance frequency).
deg), and a low-pass filter circuit for removing high-frequency components above the roll resonance frequency at which the phase delay further advances.

As described above, in this embodiment, the vertical G sensor 1 and the filter circuit of FIG. 14 constitute a sprung vertical speed detecting means, and the horizontal G sensor 2 and FIG.
The filter circuit of No. 5 constitutes a lateral acceleration detecting means in the claims.

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 pressure-side damping valve 20 and an extension-side damping valve 12 for opening and closing 31a and 31b, respectively, are provided. A stud 38 that penetrates the piston 31 is screwed and fixed to the bound stopper 41 screwed to the tip of the piston rod 7, and the stud 38 bypasses the through holes 31a and 31b. Communication for forming flow paths (extension-side second flow paths E, expansion-side third flow paths F, bypass flow paths G, and compression-side second flow paths J to be described later) that communicate the upper chamber A and the lower chamber B. A hole 39 is formed.
An adjuster 40 for changing the flow path cross-sectional area of the flow path is rotatably provided in 9. Also, stud 38
The communication hole 3 is formed on the outer periphery of the communication hole 3 in accordance with the direction of fluid flow.
An expansion-side check valve 17 and a compression-side check valve 22 that allow and shut off the flow on the flow path side formed by 9 are provided. Note that the adjuster 40 is provided with the pulse motor 3.
Is rotated through the control rod 70 (see FIG. 4). Also, studs 38
A first port 21, a second port 13, a third port 18, a fourth port 14, and a fifth port 16 are formed in this order from the top.

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 the 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, a through-hole 31 is provided as a flow path through which fluid can flow in the extension stroke.
b, the inside of the extension side damping valve 12 is opened to open the lower chamber B
, The second port 13, the vertical groove 23,
Via the second port 13, the vertical groove 23, and the fifth port 16 via the fourth port 14, the outer peripheral side of the extension side damping valve 12 is opened to open the outer peripheral side of the extension side damping valve 12 to reach the lower chamber B, Then, the extension side check valve 17 is opened to open the extension side third flow path F to the lower chamber B, and the bypass to the lower chamber B via the third port 18, the second horizontal hole 25, and the hollow portion 19. There are four flow paths G. In addition, as a flow path through which fluid can flow in the pressure stroke, the pressure side first valve that opens the pressure side damping valve 20 through the through hole 31a.
Channel H, hollow portion 19, first lateral hole 24, first port 21
, The pressure-side second flow path J that opens the pressure-side check valve 22 to reach the upper chamber A through the air passage, and the bypass flow that reaches the upper chamber A through the hollow portion 19, the second horizontal hole 25, and the third port 18. Road G
And three flow paths.

That is, the shock absorber SA is configured such 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, when the adjuster 40 is rotated counterclockwise from a state where both the extension side and the compression side are soft (hereinafter, referred to as a soft area SS), the attenuation characteristic of the extension side only is multi-stepped. It is possible to change the compression side to a region where the compression side is 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 of only the compression side can be changed in multiple stages. The extension side has a structure fixed to a low attenuation characteristic (hereinafter referred to as a compression side hard area SH).

In FIG. 7, the KK section, the LL section, the MM section, and the NN section in FIG. 8, 9 and 10 and the damping force characteristics at each position are shown 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 signal and the lateral acceleration signal obtained from 1, 1, 1 and the lateral G sensor 2 are converted into respective filter circuits LPF1, LPF.
2, BPF1, BPF2 or HPF1, LPF
3, in the process to bouncing component signal v, the pitch component signal v ', a step of performing a process of obtaining a roll component signal G _G. Note that the bounce component signal v and the pitch component signal v ′
Is given as a positive value when the sprung vertical acceleration is in the upward direction, and is given as a negative value when the sprung vertical acceleration is in the downward direction. Further, the roll component signal G _G shock absorber SA in the acceleration direction
Is given as a negative value because it is on the sinking side (pressure stroke side) of the vehicle body, and a positive value is given on the shock absorber SA on the side opposite to the acceleration direction because it is on the rising side (extending stroke side) of the vehicle body. Given by

Step 102 uses the following equation (1).
Each component signal v, v ', a step of computing the control signal V of the position of each wheel _{(V 1, V 2, V} 3, V 4) based on G _G.

[0022]

(Equation 1) Note that α _f , β _f , and γ _f are the respective proportional constants of the front wheels α _r , β _r , and γ _r are the respective proportional constants of the rear wheels.

In each equation, the portion 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.

Step 103 is a step for determining whether or not the control signal V is a positive value. If YES, the process proceeds to step 104, and if NO, the process proceeds to step 105.

In step 104, the shock absorber S
This is a step of controlling A to the extension-side hard area HS.

Step 105 is a step for determining whether or not the control signal V is 0.
Proceed to 06, and proceed to step 107 with NO.

In step 106, the shock absorber S
This is the step of controlling A to the soft area SS.

Step 107 is a step displayed for the sake of convenience.
When it is determined to be O, the control signal V is a negative value,
In this case, the process proceeds to step 108.

In step 108, 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 control signal V changes as shown in this figure, as shown in the figure, when the control signal V is 0,
The shock absorber SA is controlled to the soft area SS.

When the control signal V has a positive value, the compression side is controlled to the expansion side hard region HS to fix the compression side to low attenuation characteristics, while changing the expansion side attenuation characteristics in proportion to the control signal V. . At this time, the attenuation characteristic C is controlled so that C = k ₁ · V. Note that the k ₁ is a proportionality constant of the extension phase.

When the control signal V becomes a negative value, the compression side hard region SH is controlled to fix the expansion side to low attenuation characteristics, while changing the compression side attenuation characteristics in proportion to the control signal V. At this time, the attenuation characteristic C is controlled so that C = k ₂ · V. Note that the k ₂ is a proportionality constant of compression phase.

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

An area b is an area where the control signal V remains at 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 extended). Therefore, at this time, the shock absorber SA is controlled to 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. The extension stroke, which is the stroke of the absorber SA, has hardware characteristics proportional to the value of the control signal V.

Area c is a state where 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 A is the extension stroke 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. Therefore, in this region, The extension stroke side of the shock absorber SA has soft characteristics.

The region d is a region in which 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 on the extension stroke side). At this time, the shock absorber SA is controlled to the compression-side hard area SH based on the direction of the control signal V, and the stroke of the shock absorber is also the compression stroke,
Therefore, in this area, the shock absorber SA at that time is
The pressure stroke side, which is the stroke of the above, has hardware characteristics proportional to the value of the control signal V.

As described above, in this embodiment, when the sprung vertical speed and the relative speed between the sprung and unsprung have the same sign (region b, region d), the shock absorber S at that time is used.
A damping characteristic control based on the skyhook theory, in which the stroke side of A is controlled to a hard characteristic, and when the sign is different (regions a and c), the stroke side of the shock absorber SA at that time is controlled to a soft characteristic. The same control will be performed without detecting the relative speed between sprung and unsprung. Further, in this embodiment, when shifting from the area a to the area b and from the area c to the area d, the switching of the damping characteristic is performed without driving the pulse motor 3.

Next, the operation of the control unit 4 when the vehicle travels straight and during steering will be described.

(A) Straight running When the vehicle is in a straight running state, no lateral acceleration acts on the vehicle, so that the roll component signal _GG becomes 0, so that the bounce rate and the pitch based on the sprung speed are obtained. The damping characteristic of each shock absorber SA is controlled by a control signal obtained from the rate.

Therefore, not only the bounce but also a sufficient vibration damping property can be exhibited with respect to the vehicle behavior in which the bounce and the pitch are trained.

[0042] When (b) steering during steering is performed, to act lateral acceleration at the same time on the vehicle when the roll is generated in the vehicle, the roll component signal G _G increases according to the change rate by which the control The signal V increases.

That is, in the shock absorber SA on the steering direction side (the side opposite to the direction of action of the lateral acceleration), the roll component signal _GG is given as a positive value. V increases in proportion to the increase of V. In the shock absorber SA on the side opposite to the steering direction (on the side where the lateral acceleration acts), the roll component signal G
_{Since G} is given as a negative value, the damping characteristic on the pressure side increases in proportion to the increase of the control signal V, whereby the roll of the vehicle body can be sufficiently suppressed.

As described above, in this embodiment, the following effects can be obtained. Since sufficient control force can be generated not only for bounces but also for pitches and rolls, it is possible to provide a vehicle suspension system excellent in ride comfort and steering stability.

Since the frequency of switching the damping characteristic is reduced as compared with the damping characteristic control based on the conventional skyhook theory, control responsiveness can be improved and the durability of the pulse motor 3 can be improved.

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, a part of the control unit 4 is different from that of the first embodiment, and an arithmetic expression shown in the following Expression 2 is used for obtaining the control signal V.

[0049]

(Equation 2) That is, in the second embodiment, the bounce rate is independently obtained based on the sprung vertical speed of each wheel, and control can be performed with the bounce component emphasized.

(Third Embodiment) In the third embodiment, a part of the control unit 4 is different from that of the first embodiment, and the following equation 3 is used to obtain the control signal V.

[0051]

(Equation 3) That is, in the third embodiment, the bounce rate component is obtained by the average value of the bounce component signals of the left and right wheels independently on the front wheel side and the rear wheel side, and the pitch rate component is calculated by the left and right pitches of the front wheel side. This is determined by the difference between the average value of the component signals and the average value of the left and right pitch component signals on the rear wheel side. Therefore, the influence of the detection value of the acceleration sensor due to the roll of the vehicle is eliminated because the average value of the left and right wheels is taken, so that the vehicle having low body rigidity can be advantageously controlled.

(Fourth Embodiment) In a fourth embodiment, as shown in the diagram of FIG. 18, each of the upper and lower G sensors 1, 1, 1, 1 is directed toward the center axis in the width direction of the vehicle, and the right and left G sensors 1, 1, 1, 1 By mounting the two detection direction axes h, h in an inclined manner in a direction approaching each other in the upward direction, actual springs at the positions of the upper and lower G sensors 1, 1, 1, 1 based on the signals from the upper and lower G sensors 1, The bounce rate component and the pitch rate component based on the up-down speed and the roll component signal based on the change rate of the lateral acceleration acting on the vehicle body are calculated. Therefore, in this embodiment, the first embodiment The lateral G sensor 2 in the example is omitted.

That is, in this embodiment, each of the upper and lower G sensors 1
Since the but attached to the inclined, as shown in the diagram of FIG. 18, with respect to the sprung vertical acceleration value G _X real acting vertically, the detection value Gg of each vertical G sensor 1 is in the tilt direction since the component force equivalent, it is possible to determine the sprung mass vertical acceleration value G _X in reality calculated from the detection value Gg, based on the respective detected values Gg, calculating a bounce rate component and the pitch rate component Can be. It should be noted that the bounce component signal v and the pitch component signal v 'processed by the filter circuit shown in FIG. 14 are used in this arithmetic expression, as in the case of the first embodiment.

In this embodiment, as shown in the diagram of FIG. 19, when the lateral acceleration G acts on the vehicle, of the left and right upper and lower G sensors 1, 1 on the side of the lateral acceleration G acting direction. The vertical G sensor 1 detects this as a downward acceleration value (negative value), while the vertical G sensor 1 on the opposite side to the direction of action of the lateral acceleration G generates an upward acceleration value (positive value). Because it is detected, the left and right upper and lower G
By subtracting the detected acceleration value of the other upper and lower G sensor 1 from the detected acceleration value of the upper and lower G sensor 1 on the side that obtains the roll component signal, of the detected acceleration values of the sensors 1 and 1,
Lateral acceleration direction side, body sinking side (pressure stroke side)
On the side of the shock absorber SA, a lateral acceleration value G _K approximating the actual value of the lateral acceleration G is given as a negative value, and is opposite to the lateral acceleration direction and is on the rising side (extension) of the vehicle body. On the side of the shock absorber SA (stroke side), a lateral acceleration value G _K approximating the actual value of the lateral acceleration G is given as a positive value. The lateral acceleration value G _k is processed by a pair of filter circuits HPF1 and LPF3 shown in FIG. 15 to obtain a roll component signal G _G as a lateral acceleration change rate (lateral jerk). Is converted to

Therefore, in this embodiment, the following equation 4 is used to determine the control signal V.
In this embodiment, the bounce rate component and the pitch rate component are determined based on the average value on the left and right.

[0056]

(Equation 4) That is, in the fourth embodiment, similarly to the third embodiment, the bounce rate component is independently calculated on the front wheel side and the rear wheel side, and the sprung vertical acceleration values G on both the left and right wheels respectively.
The pitch rate component is obtained by integrating the average value of x, and the pitch rate component is integrated with the difference between the average value of the front wheel side left and right sprung vertical acceleration Gx and the average value of the rear wheel left and right sprung vertical acceleration value Gx. This is what we asked for.

As described above, in this embodiment, the lateral G sensor can be omitted, so that the number of parts can be reduced and the cost can be reduced, and the assembling labor, assembling space and weight can be reduced. It has the feature of.

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

For example, if the inclination direction of each of the upper and lower G sensors in the fourth embodiment is the width direction of the vehicle, the inclination may be reversed in the direction opposite to that of the fourth embodiment.・ Negative is opposite to that of the fourth embodiment.

In each equation for obtaining the control signal,
The method of obtaining each rate component can be applied by arbitrarily exchanging between the mathematical expressions.

[0061]

As described above, in the vehicle suspension system according to the present invention, the damping characteristics of each shock absorber are controlled by the damping characteristics control means to determine the difference between the bounce rate based on the sprung vertical speed and the sprung vertical speed between the front and rear of the vehicle. Because the control is performed based on the control signal obtained from the pitch rate detected from and the roll rate based on the change rate of the lateral acceleration,
A sufficient control force can be obtained not only for the bounce but also for the pitch and the roll, whereby the ride comfort and the steering stability can be improved.

Each of the shock absorbers includes a compression-side hard region in which the extension side has a variable damping characteristic and the compression side has a fixed low attenuation characteristic, a compression-side hard region in which the compression side has a variable attenuation characteristic and the extension side has a fixed 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 a positive value. When the signal is a negative value, the shock absorber is controlled in the pressure-side hard range, and when the control signal is 0, the shock absorber is controlled in the soft range. Characteristics control based on the control characteristics, and the frequency of switching the damping characteristics can be reduced compared to the conventional damping characteristics control based on the skyhook theory. It can be increased, and the effect is obtained that it is possible to improve the durability of the damping characteristic switching actuator.

[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 an L sectional view and MM 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 block diagram showing a main part of the control unit of the first embodiment.

FIG. 16 is a flowchart showing a control operation of a control unit of the first embodiment.

FIG. 17 is a time chart showing the operation of the first embodiment.

FIG. 18 is a diagram illustrating the structure of the fourth embodiment device and a detection state of vertical acceleration.

FIG. 19 is a diagram illustrating the structure of the fourth embodiment device and a detection state of lateral acceleration.

[Explanation of symbols]

 a damping characteristic changing means b shock absorber c sprung vertical speed detecting means d lateral acceleration detecting means e damping characteristic controlling means

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60G 17/015 F16F 9/50

Claims (1)

(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 speed near a position where each shock absorber is provided. A sprung vertical speed detecting means, a lateral acceleration detecting means for detecting a change rate of a lateral acceleration of the vehicle, a damping characteristic of each shock absorber, a bounce rate based on the sprung vertical speed and a sprung vertical speed difference between front and rear of the vehicle. Damping characteristic control means for controlling based on a control signal obtained from a pitch rate detected from the roll rate and a roll rate based on a change rate of the lateral acceleration , wherein the shock absorber has a variable damping characteristic on the extension side and a compression side on the compression side.
Is fixed to the extension side hard region with low damping characteristics, and the compression side
The compression side has a variable pressure and the compression side is fixed to the low attenuation characteristic on the extension side,
Three areas: soft area with low damping characteristics on both extension and compression sides
And the damping characteristic control means is short-circuited when the control signal has a positive value.
The absorber is controlled in the extension side hardware area, and the control signal is
When the value is negative, the shock absorber is controlled in the pressure side
When the control signal is 0, the shock absorber is
A vehicle suspension device configured to be controlled in a region .