JP2584967Y2 - 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 a damping characteristic of a shock absorber, for example, Japanese Unexamined Utility Model Publication No.
What is described in 93203 gazette is known. This conventional vehicle suspension device has a sprung vertical speed and a sprung speed.
The relative speed between the unsprung parts is detected, and when both have the same sign,
The four-wheel independent damping characteristic control based on the Skyhook theory, in which the damping characteristics are hard and the damping characteristics are soft when both have different signs, is used.

[0003]

However, in the above-described conventional device, the above-described configuration has the above-described configuration. Therefore, when the control gain is set to a higher control gain to obtain a sufficient vibration damping property for road surface input. However, the vibration suppression effect can be obtained with respect to the low-frequency road surface input, but the responsiveness becomes too high with respect to the high-frequency road surface input, and the unsprung input is transmitted to the sprung. If the control gain is set low so that the ride comfort of the vehicle can be ensured, sufficient vibration suppression cannot be obtained for a large road surface input.

Further, in the conventional damping characteristic control based on the skyhook theory, the damping characteristic is switched by driving the actuator every time the coincidence / mismatch of both signs of the sprung vertical speed and the relative speed is switched. Because of the necessity, control responsiveness is deteriorated, and the number of times of driving of the actuator is increased, so that there is a problem that durability is reduced.

The present invention has been made in view of the above-mentioned conventional problems, and it is possible to secure a comfortable ride of a vehicle while improving control responsiveness, and to provide a sufficient vibration damping property for a large road surface input. A first object is to provide a vehicle suspension device that can obtain and improve steering stability, and a second object is to provide a vehicle suspension device that can improve control responsiveness and durability of an actuator. I have.

[0006]

In order to achieve the above object, a vehicle suspension system according to the first aspect of the present invention, as shown in a claim correspondence diagram of FIG. A shock absorber b interposed and capable of changing the damping characteristic by the damping characteristic changing means a, a sprung vertical speed detecting means c for detecting the sprung vertical speed, and a control signal based on the sprung vertical speed is inputted with a predetermined large value. When the control signal is less than the threshold value, the damping characteristic control is proportional to the control signal so that the maximum damping characteristic is obtained at the value of the basic threshold value until the control signal reaches the predetermined basic threshold value after reversing the direction. The control signal value is updated to the value of the basic threshold value until the peak value is reached when the value exceeds the basic threshold value, and the peak value is controlled until the direction of the control signal reverses from the peak value. The signal value is Control means e having a basic control unit d for performing damping characteristic control in proportion to the control signal, and when the control signal exceeds a large input threshold value, the direction of the control signal is thereafter reversed. In the meantime, the means includes a correction control unit f for performing the attenuation characteristic control based on a value obtained by multiplying the attenuation characteristic control result by the basic control unit d by a predetermined constant larger than 1.

According to a second aspect of the present invention, in addition to the above-described structure, the shock absorber includes an extension-side hard region in which the extension side has a variable damping characteristic and the compression side has a fixed low attenuation characteristic, and a compression side in which the attenuation characteristic is variable. The compression side is formed in a structure having three regions, a compression side hard region in which the extension side is fixed to low attenuation characteristics, and a soft region in which both the extension side and the compression side have low attenuation characteristics. When the control signal is a negative value, the shock absorber is controlled in the compression-side hard region, and when the control signal is 0, the shock absorber is controlled in the soft region. did.

[0008]

According to the vehicle suspension system of the present invention, as described above, when the road surface input is small, the control signal based on the sprung vertical speed is less than the predetermined large input threshold value. The section performs attenuation characteristic control proportional to the control signal so that the maximum attenuation characteristic is obtained at the value of the basic threshold value until the control signal reaches the predetermined basic threshold value after the control signal reverses direction. When the peak value is exceeded, the control signal value is updated to the basic threshold value until the peak value is reached. In addition, the proportional control of the attenuation characteristic is performed in which the value of the control signal at the peak value is the maximum attenuation characteristic until the direction of the control signal is reversed from the peak value, thereby improving the control response. Sudden damping force It is possible to ensure the ride comfort of the vehicle by eliminating the Do not change.

When the road surface input increases, the control signal exceeds the large input threshold value.
Thereafter, until the direction of the control signal is reversed, the damping characteristic control is performed based on a value obtained by multiplying the damping characteristic control result by the basic control unit by a predetermined constant larger than 1, whereby the damping characteristic control by the basic control unit is performed. Since the time during which the maximum damping characteristic is maintained is extended as compared with the case of the control, sufficient vibration damping performance for a large road surface input is obtained, and the steering stability of the vehicle can be secured.

According to the second aspect of the present invention, when the control signal is a positive value, the shock absorber is controlled in the extension side hard region (the pressure side is fixed to a low damping characteristic), and when the control signal is a negative value. The shock absorber is controlled in the compression side hard region (the extension side is fixed to low damping characteristics), and when the control signal is 0, the shock absorber is controlled in the soft region. Therefore, the control signal based on the sprung vertical speed is used. When the relative speed between the sprung and unsprung parts has the same sign, the stroke side of the shock absorber at that time is controlled to a hard characteristic, and when the sign is different,
The same control as the damping characteristic control based on the skyhook theory, in which the stroke side of the shock absorber at that time is controlled to a soft characteristic, can be performed without detecting the relative speed between the sprung and unsprung parts. Since the switching of the damping characteristic in the direction of the low damping characteristic is performed without driving the actuator, the frequency of the switching of the damping characteristic is reduced as compared with the damping characteristic control based on the conventional skyhook theory, and the control responsiveness is reduced. And the durability of the actuator can be improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 an explanatory view showing the structure of a vehicle suspension system according to a first embodiment which is an embodiment of the present invention according to the first and second aspects of the present invention, wherein four shocks are interposed between a vehicle body and four wheels. Absorbers SA ₁ , SA ₂ , S
A ₃ , SA ₄ (In describing the shock absorber, when these four are collectively referred to, and when describing their common configuration, they are simply indicated as SA.)
Is provided. And each shock absorber SA
Is provided with a vertical acceleration sensor (hereinafter, referred to as a vertical G sensor) 1 for detecting a vertical acceleration. Also, signals from the upper and lower G sensors 1 are input to the positions near the driver's seat, and the shock absorbers 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 interface circuit 4a includes the above-described upper and lower G sensors 1 and A signal from the vehicle speed sensor 5 is input. In the interface circuit 4a, a set of five 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 a bounce component signal v (v ₁ , v ₂ , v
_3, v ₄ The numbers _{1, 2, 3 and 4} correspond to the position of the shock absorbers SA. The same applies to the following. ) Is a band-pass filter circuit. The BPF ₂ is a bandpass filter circuit that forms a pitch component signal v ′ (v ₁ ′, v ₂ ′, v ₃ ′, v ₄ ′) by passing a frequency range including a pitch resonance frequency. The BPF ₃ is a band-pass filter circuit that forms a roll component signal v ″ (v ₁ ″, v ₂ ″, v ₃ ″, v ₄ ″) by passing through a frequency range including the roll resonance frequency. In the example, the sprung resonance, pitch resonance, and roll resonance frequencies are
Although different cases are taken as an example, when these resonance frequencies are close to each other, the band-pass filter is set to BPF1.
Only need.

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 a 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. The adjuster 40 is rotated by the pulse motor 3 via a control rod 70 (see FIG. 4). The first port 21, the second port 13, the third port 18, the fourth port 14, and the fifth port 16 are formed on the stud 38 in 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, and the second port 13, the vertical groove 23, and the fifth port 16. 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 a fluid can flow during 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 FIGS.
This will be described with reference to the flowchart of FIG. This control is performed separately for each shock absorber SA.

First, referring to FIG.
Calculates the vertical acceleration obtained from each of the vertical G sensors 1, 1, 1, 1 with each of the filter circuits LPF1, LPF2, BPF1,
In this step, the bounce component signal v, the pitch component signal v ′, and the roll component signal v ″ are processed by the BPF2 and BPF3. These component signals are positive when the sprung vertical acceleration is in the upward direction. , And a negative value in the downward direction.

In step 102, the proportional constants α (α _f , α _r ), β (β _f , β _r ), γ (γ) of the respective component signals v, v′v ″ are determined according to the vehicle speed signal obtained from the vehicle speed sensor 5. γ _f , γ
_r ) is a step of setting.

Step 103 uses the following equation (1).
Based on the component signals v, v'v "and the proportional constants α, β, γ, the control signals V (V ₁ , V ₂ , V ₃ , V
₄ ) This is the step of calculating.

[0023]

(Equation 1) Note that α _f , β _f , and γ _f are proportional constants α _r , β
_r and γ _r are the respective proportional constants of the rear wheels. In each equation, the part bounded by the first α _f and α _r is the bounce rate, and the part bounded by β _f and β _r is the pitch rate. Yes, the portion between γ _f and γ _r is the roll rate.

Step 104 is a step for determining whether or not the control signal V is a positive value (upward).
ES (upward) proceeds to step 105, and NO (downward) proceeds to step 120.

Step 105 is a step for judging whether or not the previous control signal V _-1 has a negative value. YES
(Downward) proceeds to step 106, and NO (upward) proceeds to step 107. That is, in this step, it is determined whether or not the direction of the control signal has been reversed from a negative value to a positive value.

Step 106 is a step of setting an initial value V _INIT of the basic threshold value V _MAX of the upward (extending) control signal V and clearing the flag.

In step 107, the control signal V is set to the initial value V
_INIT
The process proceeds to step 108 with ES (or more), and proceeds to step 109 with NO (less than).

Step 108 is a step of updating the value of the basic threshold value V _{MAX to} the value of the control signal V at that time.

Step 109 is a step for judging whether or not the updated value of the basic threshold value V _MAX is equal to or larger than the large input threshold value V _TH.
Proceed to 10 and proceed to step 111 with NO (less than).

Step 110 is a step of setting a flag.

Step 111 is a step for calculating the basic target position T _P1 of the extension-side damping characteristic by the following equation.

T _P1 = V / V _MAX × P _MAX where V _MAX indicates the updated basic threshold value.

Step 112 is a step of determining whether or not the flag is set. If YES (set), the process proceeds to step 113; if NO (clear), the process proceeds to step 114.

Step 113 is the basic target position T
_P1 to a step of calculating the corrected target position T _P2 multiplied by a constant greater than 1 (1.5).

At step 114, the target position T _P
This is a step of determining whether (T _P1 , T _P2 ) is _{equal to} or greater than the maximum attenuation position P _MAX , and if YES, step 1
Proceed to 15 and proceed to step 116 with NO.

[0036] Step 115 is a step of updating the target position T _P of the extension side damping characteristics to the maximum attenuation position P _MAX.

[0037] Step 116 is a step of driving the step motor 3 to the target position T _P,
This completes one flow.

Next, proceeding to FIG. 16, step 120 comprises:
This is a step of determining whether or not the control signal V is 0. If YES, proceed to Step 121;
Proceed to 22.

At step 121, the target position T _P ,
This is a step of setting T- _P to 0 (soft area SS), and this ends one flow.

Step 122 is a step for judging whether or not the previous control signal V _-1 has a positive value. YES
(Upward) proceeds to step 123, and NO (downward) proceeds to step 124. That is, in this step, it is determined whether or not the direction of the control signal V has been reversed from a positive value to a negative value.

Step 123 is a step of setting the initial value V- _INIT of the basic threshold value V- _MAX of the control signal V in the downward direction (pressure side) and clearing the flag.

In step 124, the control signal V is set to the initial value V
_-INIT or less,
YES (hereinafter) proceeds to step 125, and NO proceeds to step 126.

Step 125 is a step of updating the value of the basic threshold value V- _{MAX to} the value of the control signal V at that time.

Step 126 is a step for judging whether or not the updated value of the basic threshold value V- _MAX is equal to or less than the large input threshold value V- _TH. , NO, the process proceeds to step 128.

Step 127 is a step of setting a flag.

Step 128 is a step for calculating the basic target position T- _P1 of the _compression- side damping characteristic by the following equation.

T _-P1 = V / V _-MAX * P _-MAX where V _-MAX indicates the updated basic threshold value.

Step 129 is a step for determining whether or not the flag is set. If YES (set), the process proceeds to step 130, and if NO (clear), the process proceeds to step 131.

Step 130 is the basic target position T
_This is a step of calculating a correction target position T- _P2 by multiplying _-P1 by a constant (1.5) larger than 1.

At step 131, the target position T
_This is a step for determining whether or not _-P (T _-P1 , T _-P2 ) is equal to or less than the maximum attenuation position P _-MAX . If YES, the process proceeds to step 132, and if NO, the process proceeds to step 133.

[0051] Step 132 is a step of updating the target position T _-P pressure side damping characteristics to the maximum attenuation position P _-MAX.

Step 133 is a step of driving the step motor 3 toward the target position _TP .
This completes one flow.

Next, the operation of the embodiment apparatus will be described with reference to FIGS.
8 will be described. First, the time chart of FIG. 17 will be described. From the top, the control signal V, the ON / OFF state of the large input control condition, and the fluctuation of the target position of the pulse motor 3 are shown.

First, when the control signal V is between the initial values V _INIT and V _-INIT of the basic threshold value, step 1 in FIG.
The 11 and step 128 in FIG. 16, the control signal V is proportional control of the damping characteristic as Shin圧各damping characteristics of the shock absorber SA becomes the maximum at the initial value V _INIT, the value of V _-INIT basic threshold Done.

Therefore, the sensitivity at the time of the rise of the damping force is increased, and the control response can be improved.

When the control signal V _exceeds the range of the initial values of the basic thresholds V _INIT and V _-INIT , the basic thresholds V _MAX and V _MAX are obtained in steps 108 and 125 of FIG. _{Since -MAX} is updated to the value of the control signal V at that time, the expansion characteristics of the shock absorber SA are maintained at the maximum until the peak value is reached. Until the direction is reversed, the damping characteristic control (basic control) proportional to the control signal V having the peak value of the control signal V as the maximum damping characteristic is performed in step 111 of FIG. 15 and step 128 of FIG. Is performed.

Accordingly, the ride comfort of the vehicle can be ensured without sharp changes in the damping force while improving the control response.

When the control signal V is large input threshold values V _TH , V _-TH
When the direction of the control signal V is reversed after that, the basic target positions T _P1 and T _{-P1 are determined} by Step 113 in FIG. 15 and Step 130 in FIG.
_Is multiplied by a predetermined constant (1.5) larger than 1 to perform the damping characteristic control (correction control) based on the correction target positions _TP2 and T- _P2 .

When the correction control is performed as described above, the time for maintaining the maximum damping characteristic is extended as compared with the case where the basic control indicated by the dotted line is performed, so that the damping force is increased only in the hatched portion. State.

Accordingly, it is possible to enhance the vibration damping performance of the vehicle at the time of a large input, thereby improving the steering stability.

Next, the time chart of FIG. 18 will be described. Note that the time chart shows a case where the control signal V is changed by less than atmospheric input threshold V _TH, the V _-TH range.

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

Further, when the control signal V becomes a positive value, the compression side is controlled to the expansion side hard region HS to fix the compression side to low attenuation characteristics.

When the control signal V becomes a negative value, the compression side is controlled to the compression side hard region SH to fix the extension side to the low attenuation characteristic.

In the time chart of FIG.
The area a is a state in which the control signal V based on the sprung vertical speed 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 shock absorber SA has a negative value). Since the stroke is a 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 area, the shock absorber SA at that time is
The pressure stroke side, which is the stroke of, has soft characteristics.

In the area b, the control signal V based on the sprung vertical speed remains a positive value (upward), and the relative speed changes from a negative value to a positive 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 extension-side hard area HS based on the direction of the control signal V, and the stroke of the shock absorber is also the extension stroke. In this region, the extension stroke, which is the stroke of the shock absorber SA at that time, has a hard characteristic proportional to the value of the control signal V.

The area c is a state in which the control signal V based on the sprung vertical velocity is reversed from a positive value (upward) to a negative value (downward), but at this time, the relative velocity is still a positive 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 region SH based on the direction of the control signal V. Then, the extension stroke side, which is the stroke of the shock absorber SA at that time, has the soft characteristic.

In the area d, the control signal V based on the sprung vertical speed 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 pressure 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, and the stroke of the shock absorber is also the compression stroke. Therefore, in this region, The pressure stroke side, which is the stroke of the shock absorber SA at that time, 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.

As described above, in this embodiment, the following effects can be obtained. The correction control is performed only when the input is large, so that the control response is improved by the basic control when the input is small and the ride comfort of the vehicle can be secured. It is possible to provide a vehicle suspension device capable of achieving vibration suppression and improving steering stability.

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 having excellent ride comfort and steering stability.

As compared with the conventional damping characteristic control based on the skyhook theory, the frequency of switching the damping characteristics is reduced, so that the 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 the 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.

[0076]

(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.

Although the embodiment has been described above, the specific configuration is not limited to this embodiment, and even if there is a design change or the like within a range not departing from the gist of the present invention, it is included in the present invention.

For example, in the embodiment, the extension side hard region in which the expansion side is variable in attenuation characteristic and the compression side is fixed to the low attenuation characteristic, the compression side in which the attenuation side is variable in attenuation characteristic and the extension side is fixed in the low attenuation characteristic, -Although the shock absorber having three regions, that is, a soft region having a low damping characteristic on both the compression side and the compression side is used, a shock absorber having a structure in which the extension side and the compression side attenuation characteristics change simultaneously can be used.

[0079]

As described above, according to the vehicle suspension system of the present invention, when the control signal based on the sprung vertical speed is less than the predetermined large input threshold value, the control signal is reversed after the control signal is reversed. Until the basic threshold value is reached, attenuation characteristic control proportional to the control signal is performed so that the maximum attenuation characteristic is obtained at the value of the basic threshold value. The control signal value is updated to the value of the basic threshold value, and the damping characteristic control is proportional to the control signal in which the value of the peak value control signal is the maximum damping characteristic until the direction of the control signal is reversed from the peak value. A control unit having a basic control unit for performing the damping characteristic control by the basic control unit provided that the control signal becomes equal to or larger than the large input threshold value until the direction of the control signal is reversed. Greater than 1 for result With a configuration including a correction control unit that performs damping characteristic control based on a value multiplied by a predetermined constant, for a small road surface input, the control operation of the basic control unit increases the control responsiveness while increasing the control responsiveness. In addition to the above, it is possible to obtain an effect that, for a large road surface input, a sufficient damping property can be obtained by the control operation of the correction control section, and the steering stability can be improved.

According to a second aspect of the present invention, in the vehicle suspension system, each of the shock absorbers includes an extension side hard region in which the extension side has a variable damping characteristic and a compression side fixed to a low attenuation characteristic, and a compression side in which the attenuation characteristic is variable and the extension side has a low attenuation. A structure having three regions, a compression-side hard region fixed to the characteristic and a soft region having a low attenuation characteristic on both the extension side and the compression side, and the damping characteristic control means is provided with a shock absorber when the control signal is a positive value. When the control signal is a negative value, the shock absorber is controlled in the compression-side hard region, and when the control signal is 0, the shock absorber is controlled in the soft region. This makes it possible to control the damping characteristics based on the Skyhook theory without using speed detection means. Can be reduced, thereby, it is possible to increase the control response, 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 vehicle suspension device according to the present invention.

FIG. 2 is a structural explanatory view showing the vehicle suspension device of the 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 flowchart showing a control operation 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 time chart showing the operation of the first embodiment.

[Explanation of symbols]

 a damping characteristic changing means b shock absorber c sprung vertical speed detecting means d basic control part e control means f correction control part

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B60G 17/00-17/08

Claims (2)

(57) [Scope of request for utility model registration] 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, a sprung vertical speed detecting means for detecting a sprung vertical speed, a sprung vertical speed When the control signal based on the speed is less than the predetermined large input threshold, the maximum attenuation characteristic is obtained at the value of the basic threshold until the control signal reaches the predetermined basic threshold after reversing the direction. Controls the attenuation characteristic in proportion to the control signal so that the control signal value is updated to the value of the basic threshold value until the peak value is reached when the value exceeds the basic threshold value. A control unit having a basic control unit for performing attenuation characteristic control in proportion to a control signal having a peak value control signal value as a maximum attenuation characteristic until the control signal is reversed; Input threshold Then, until the direction of the control signal is reversed, a correction control unit that performs attenuation characteristic control based on a value obtained by multiplying the attenuation characteristic control result by the basic control unit by a predetermined constant greater than 1; A vehicle suspension device comprising: 2. A compression-side hard region in which the expansion side has a variable damping 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 three regions of a soft region having a low damping characteristic 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. 2. The system according to claim 1, wherein when the signal is a negative value, the shock absorber is controlled in a pressure side hard region, and when the control signal is 0, the shock absorber is controlled in a soft region.
The vehicle suspension according to any one of the preceding claims.