JP3083116B2 - 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 coefficient of a shock absorber.

[0002]

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

In this conventional vehicle suspension system, when the direction code of a sprung vertical speed signal obtained by processing a signal of a sprung vertical acceleration sensor and a relative speed signal between a sprung and unsprung speed are the same, a damping coefficient is obtained. Is hardened, and the damping coefficient is softened when the sign is different, and the damping coefficient is controlled independently for the four wheels.

[0004]

However, in the above-mentioned conventional apparatus, since the damping coefficient is controlled based on the sprung vertical speed signal, there are the following problems.

Namely, a high-pass filter cut-off frequency 1.0 H _Z as the phase characteristic diagram (bandpass filter sprung mass vertical velocity signals for the vibration frequency of FIG. 20,
As shown in the characteristic diagram) when using a low-pass filter of 1.5 H _Z, the phase characteristics of the sprung mass vertical velocity signals, ideal velocity phase as the vibration frequency increases beyond the resonance frequency range spring (-90 Since the phase delay with respect to drg) increases, the damping coefficient control based on the sprung vertical velocity signal causes the control responsiveness to decrease by the amount of the phase delay, causing a delay in the generation of the damping force. As shown by the characteristic of the vibration transmissibility on the sprung with respect to the vibration frequency (solid line), the vibration transmissibility on the sprung becomes higher in a region slightly exceeding the sprung resonance frequency having a large influence on the ride comfort. The ride comfort of the vehicle cannot be improved.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and it is possible to eliminate a phase lag of a control signal with respect to a vibration frequency exceeding a sprung resonance frequency, thereby improving the riding comfort of a vehicle. It is an object to provide a vehicle suspension device.

[0007]

Accordingly, in the present invention, a control signal is obtained by adding a correction value obtained from the sprung vertical velocity to the sprung vertical velocity, and the damping coefficient is controlled based on the control signal. The goal was achieved.

That is, the vehicle suspension according to the first aspect of the present invention is interposed between the vehicle body side and each wheel side, and the damping coefficient is changed by the damping coefficient changing means a, as shown in the claim correspondence diagram of FIG. A possible shock absorber b, a sprung vertical acceleration detecting means c for detecting a sprung vertical acceleration near a position where each shock absorber b is provided, and a sprung vertical acceleration near a position where each shock absorber b is provided A sprung vertical speed detecting means d for detecting a speed, and a damping coefficient controlling means e for controlling a damping coefficient of each shock absorber b based on a control signal obtained by adding a correction value obtained from a sprung vertical acceleration to a sprung vertical speed. And

A vehicle suspension system according to a second aspect is provided with a shock absorber b interposed between the vehicle body side and each wheel side and capable of changing a damping coefficient by damping coefficient changing means a, and each shock absorber b. A sprung vertical acceleration detecting means c for detecting a sprung vertical acceleration near a position where the shock absorber is located; a sprung vertical speed detecting means d for detecting a sprung vertical speed near a position where each shock absorber is provided; sprung near the position where b is provided.
A relative speed detecting means f for detecting an unsprung relative speed, and a damping coefficient of each shock absorber b, a control signal obtained by adding a correction value obtained from a sprung vertical speed to a sprung vertical speed, a control signal is obtained. When the relative speed between the sprung portion and the unsprung portion has the same sign, the damping coefficient is increased.

The shock absorber includes a compression-side hard region in which the compression side has a variable damping coefficient and a compression side in which the compression side is fixed to a low damping coefficient, The damping coefficient control means is formed to have a structure having three regions of a soft region having a low damping coefficient on both the side and the pressure side, and the damping coefficient control means sets the shock absorber to the extension side hard region when the control signal is equal to or more than a positive threshold value. When the control signal is below the negative threshold, the shock absorber is controlled in the pressure side hard range, and when the control signal is between the positive and negative thresholds, the shock absorber is controlled in the soft range. May be.

In obtaining the control signal,
The sprung vertical speed and the sprung vertical acceleration may use a signal passed through a band-pass filter including a sprung resonance frequency of each of the front and rear wheels.

[0012]

[Effect] Each sprung vertical speed detecting means and the sprung vertical acceleration detecting means move the sprung up and down (bouncing).
Is detected, the damping coefficient control means obtains a control signal based on the sprung vertical speed and a correction value obtained from the sprung vertical acceleration, and controls the damping coefficient of the shock absorber according to the control signal.

In this control, the sprung vertical acceleration signal always leads the sprung vertical speed signal in phase, and the acceleration value increases as the vibration frequency increases. By performing the damping coefficient control based on a control signal obtained by adding the correction value obtained from the acceleration signal to the sprung vertical velocity signal, control responsiveness to a high-frequency input is improved.

Therefore, the phase lag of the control signal with respect to the vibration frequency exceeding the sprung resonance frequency is eliminated, and the control responsiveness is improved, so that the riding comfort of the vehicle can be improved.

In the apparatus according to the second aspect, the damping coefficient control means increases the damping coefficient when the control signal and the relative speed between the sprung and unsprung parts have the same sign. In such a case, the attenuation coefficient is minimized. Also in this case, the phase lag of the control signal with respect to the vibration frequency exceeding the sprung resonance frequency is eliminated, and the control responsiveness is improved, so that the riding comfort of the vehicle can be improved.

[0016]

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 which is an embodiment of the invention as set forth in claims 1, 3, 4;
And four shock absorbers SA ₁ , SA ₂ , SA ₃ , and SA ₄ interposed between the two wheels (in the description of the shock absorber, when referring to these four together, and their common configuration) Is described simply as SA.). And, on the vehicle body in the vicinity of each shock absorber SA,
Vertical acceleration sensor that detects sprung vertical acceleration
An upper and lower G sensor 1 is provided. Also, a signal from each sensor 1 is input to a position near the driver's seat,
A control unit 4 for outputting a drive control signal to the pulse motor 3 of each shock absorber SA 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 a signal from each of the sensors 1 described above. Is entered. In the interface circuit 4a, a set of three filter circuits shown in FIG. That is, LPF1
Is a low-pass filter circuit for removing high-frequency (30 Hz or more) noise from signals sent from the upper and lower G sensors 1. BPF is passed through a frequency range including the sprung resonance frequency of the sprung mass vertical acceleration bouncing component signal _{a (a 1, a 2,} a 3, a 4 Incidentally, _{1,2, 3,4} figures each shock corresponds to the position of the absorber SA. the same applies is less.) is a band-pass filter circuit forming the, in this embodiment, a high-pass filter cut-off frequency 1.0 H _Z, a low-pass filter of 1.5 H _Z It consists of. LPF2 is a band-pass filter circuit B
Bounce component signal a of the sprung vertical acceleration that passed through the PF
Is integrated and the bounce component signal v (v
₁ , v2, _v3 , _v4 The numbers ₁ , ₂ , ₃ , ₄ correspond to the positions of the respective shock absorbers SA. The same applies to the following. ) Is a low-pass filter circuit. FIG. 19 shows a gain characteristic of the signal processed by the BPF with respect to the vibration frequency.

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. And a piston 32
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 portion of the piston 31. As shown in FIG. 5, the piston 31 has through holes 31a and 31b and An extension damping valve 12 and a compression damping valve 20 for opening and closing 31a and 31b, respectively, are provided. A communication hole 39 that connects the upper chamber A and the lower chamber B is formed at the tip of the piston rod 7 that penetrates the piston 31, and further changes the cross-sectional area of the communication hole 39. , And an expansion-side check valve 17 and a pressure-side check valve 22 that allow and shut off the flow of the fluid communication hole 39 in accordance with the flow direction of the fluid. The adjuster 40 is rotated by the pulse motor 3 (see FIG. 4).
Also, the first end of the piston rod 7 is
A port 21, a second port 13, a third port 18, a fourth port 14, and a fifth port 16 are formed. Also in the figure

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

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

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

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

In step 101, the upper and lower G sensors 1,
The vertical acceleration obtained from each of the filter circuits L
This is a step of performing processing for obtaining a sprung vertical acceleration signal a and a sprung vertical velocity signal v as bounce components by processing with the PF1, BPF, and LPF2.

Step 102 uses the following equation (1).
Based on the signals a and v, the control signal V (V
_{1, V 2, V 3,} V 4) is a step of computing.

[0027] <number 1> front wheel right _{V 1 = v 1 + A f} · a 1 front wheel left _{V 2 = v 2 + A f} · a 2 rear wheel right _{V 3 = v 3 + A r} · a 3 rear wheel left V ₄ = _{v 4 + a r · a 4} ( correction value) Note, a _f is the front wheels of the proportional constant a _r, the rear wheel proportionality constant a _1: on front right spring vertical acceleration signal a _2: on the front wheel left the spring vertical Acceleration signal a ₃ : Rear wheel right sprung vertical acceleration signal a ₄ : Rear wheel left sprung vertical acceleration signal v ₁ : Front wheel right sprung vertical speed signal v ₂ : Front wheel left sprung vertical speed signal v ₃ : rear wheel right sprung mass vertical velocity signal v _4: a sprung mass vertical velocity signal of the rear wheel left.

In each equation, A _f · a ₁ , A _r ·
portions of a ₁ is a correction value. FIG. 18 shows the sprung vertical speed signal v ₁ , the control signal V _1, and the correction value A _f · a ₁
FIG. 19 is a time chart showing the change characteristics of FIG.
Is a low frequency (1.0 _Hz ) input, and (b) of FIG. 18 is a high frequency (2.
0 _Hz ) shows characteristics at the time of input. That is, as shown in this figure, at the time of low frequency (1.0 _Hz ) input, the fluctuation range of the correction value A _f · a ₁ is small, so that the phase of the control signal V ₁ with respect to the sprung vertical speed signal v ₁ Advance amount s
_{While 1} is small, at the time of high frequency (2.0 _Hz ) input, the fluctuation range of the correction value A _f · a ₁ becomes large, so that the phase advance of the control signal V ₁ with respect to the sprung vertical speed signal v ₁ is advanced. but the amount s ₂ is increased, thereby, it is possible to cancel the phase lag of the control signal V ₁ with respect to vibration frequency in the high frequency range.

As described above, the sprung vertical speed and the correction value are obtained from the signals from the upper and lower G sensors 1. The upper and lower speed detecting means and the sprung vertical acceleration detecting means are constituted.

[0030] Step 103, the control signal V is a step equal to or larger than a predetermined threshold value [delta] _T, the process proceeds to step 104 in YES, a step 1 is NO
Go to 05.

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

[0032] Step 105 is a step of determining whether a value between the control signal V is a predetermined threshold value [delta] _T and the threshold - [delta _C, the process proceeds to step 106 YES, a by NO Proceed to step 107.

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

[0034] Step 107 is a step of displaying convenience, when the result of determination is NO in step 103 and step 105, the control signal V is less than a predetermined threshold value - [delta _C, in this case, Go 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, when the control signal V is a value between the predetermined threshold values δ _T , -δ _C , the shock absorber SA is controlled to the soft region SS. I do.

When the control signal V becomes equal to or larger than the threshold value δ _{T, the} compression side is controlled to the expansion side hard region HS so that the compression side is fixed to a low attenuation coefficient, while the expansion side attenuation coefficient is made proportional to the control signal V. Change. At this time, the attenuation coefficient C is C = kV
Is controlled so that Here, k indicates a proportional constant.

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

As described above, in the vehicle suspension system of the first embodiment, the correction value A _f · a ₁ obtained from the sprung acceleration signal a _{1 is different} from the sprung vertical speed signal v ₁ . always with is advanced in phase, since the advancing amount increases as the vibration frequency becomes higher, the control signal V ₁ obtained by adding the correction value a _f · a ₁ to sprung mass vertical velocity signal v ₁ by performing the damping coefficient control based on the phase delay of the control signal V ₁ with respect to the vibration frequencies above sprung resonance frequency is eliminated by improved control response is, thereby, as indicated by a dotted line in FIG. 17, It has the characteristic that the transmission rate to the sprung in the sprung resonance frequency range is reduced, and the riding comfort of the vehicle can be improved.

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

In the second embodiment, as shown in FIG. 22, as input means, in addition to the sprung G sensor 1, a load sensor (a relative speed detecting means between sprung and unsprung) is used.
6 are provided. The load sensor 6 is provided at a portion where the shock absorber SA is attached to the vehicle body, and detects a damping force (corresponding to a relative speed) F generated at the shock absorber SA as a load. .

Control unit 304 of the second embodiment
23 will be described with reference to the flowchart of FIG. 23. In step 301, the damping force F detected by the load sensor 6 is determined.
After this processing, the process goes through steps 101 and 102 similar to the first embodiment, and then proceeds to step 302.

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

In step 303, the damping force F becomes F = k
-Change the damping coefficient so that it becomes V.

In step 304, the damping coefficient of the shock absorber SA is controlled so that both the extension and the pressure become the minimum damping coefficients.

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

[0049]

As described above, in the vehicle suspension system of the present invention, a control signal obtained by adding a correction value obtained from the sprung vertical acceleration to the sprung vertical speed is obtained. By controlling the damping coefficient of the shock absorber based on the above, the phase response of the sprung vertical velocity for the vibration frequency exceeding the sprung resonance frequency is eliminated by the phase advance of the sprung vertical acceleration, and the control response Therefore, it is possible to obtain the effect that the transmission rate to the sprung portion in the vibration frequency region exceeding the sprung resonance frequency is reduced, and the riding comfort of the vehicle can be improved.

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

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

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

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

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

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

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

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

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

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

FIG. 17 is a graph showing a characteristic of a vibration transmission rate on a sprung with respect to a vibration frequency of the device of the first embodiment.

FIG. 18 is a time chart showing a change characteristic of a sprung vertical speed signal, a control signal, and a correction value of the first embodiment device.

FIG. 19 is a graph showing a gain characteristic with respect to an oscillation frequency of a signal processed by the BPF of the first embodiment.

FIG. 20 is a phase characteristic diagram of a sprung vertical velocity signal with respect to a vibration frequency of the first embodiment device.

FIG. 21 is a damping coefficient characteristic diagram of a shock absorber of the device of the second embodiment.

FIG. 22 is a system block diagram illustrating a device according to a second embodiment.

FIG. 23 is a flowchart showing a control operation of a control unit of the second embodiment.

[Explanation of symbols]

 a damping coefficient changing means b shock absorber c sprung vertical acceleration detecting means d sprung vertical speed detecting means e damping coefficient controlling means f sprung and unsprung relative speed detecting means

Claims (4)

(57) [Claims] 1. A shock absorber interposed between a vehicle body side and each wheel side and capable of changing a damping coefficient by damping coefficient changing means, and detecting a sprung vertical acceleration near a position where each shock absorber is provided. A sprung vertical acceleration detecting means, a sprung vertical speed detecting means for detecting a sprung vertical speed near a position where each shock absorber is provided, and a damping coefficient of each shock absorber is set to a sprung vertical speed to a sprung vertical speed. And a damping coefficient control means for controlling based on a control signal to which a correction value obtained from the acceleration is added. 2. A shock absorber interposed between a vehicle body side and each wheel side and capable of changing a damping coefficient by damping coefficient changing means, and detecting a sprung vertical acceleration near a position where each shock absorber is provided. A sprung vertical acceleration detecting means, a sprung vertical speed detecting means for detecting a sprung vertical speed near a position where each shock absorber is provided, and a sprung and unsprung near a position where each shock absorber is provided A relative speed detecting means for detecting an inter-relative speed; a damping coefficient of each shock absorber; a control signal obtained by adding a correction value obtained from a sprung vertical speed to a sprung vertical speed; A damping coefficient control means for controlling the damping coefficient to be minimized when the relative speed between the lower sign and the same sign is the same sign, while the damping coefficient is increased when the relative speed is different sign. Vehicle suspension system, characterized in that. 3. A compression-side hard region in which a compression side has a variable damping coefficient and a compression side is fixed to a low damping coefficient, a compression-side hard region in which the compression side has a variable damping coefficient and a expansion side is fixed to a low damping coefficient. The damping coefficient control means is formed in a structure having three regions of a soft region having a low damping coefficient on both the side and the pressure side, and the damping coefficient control means controls the shock absorber in the expanding hard region when the control signal is equal to or more than a positive threshold value. When the control signal is equal to or less than the negative threshold, the shock absorber is controlled in the pressure side hard region, and when the control signal is between the positive and negative thresholds, the shock absorber is controlled in the soft region. The vehicle suspension device according to claim 1, wherein: 4. The method according to claim 1, wherein the control signal is obtained by using a signal passed through a band-pass filter including a sprung resonance frequency of each of the front and rear wheels as the sprung vertical speed and sprung vertical acceleration. The vehicle suspension according to claim 1 or 2.