JP3114891B2 - 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.

This conventional vehicle suspension detects a sprung vertical speed and a relative speed between sprung and unsprung, and sets the damping coefficient to hard when both have the same sign, and sets the damping coefficient when both have different signs. The damping coefficient control, such as softening, is performed independently for the four wheels.

[0004]

However, the conventional apparatus has the above-described structure, and therefore, when the characteristics of the hardware suitable for the case where the vehicle body is moving in the bounce direction, the bounce and the In the case of body motion coupled with pitching, since the body moment of inertia around the center of gravity of the center of the body is added to the sprung mass, the damping force (control force) is insufficient, and the steering stability is poor. there were.

The present invention has been made in view of the above-mentioned conventional problems, and it is as simple as possible to improve the steering stability by obtaining a sufficient damping property against the moment of inertia. That is the purpose.

[0006]

In the present invention, a bounce component, a pitch component, and a roll component are detected, and the damping coefficient is controlled based on the front wheel control signal and the rear wheel control signal obtained from these components. To achieve the above object.

[0007] That is, the vehicle-cum-device of the present invention is shown in FIG.
As shown in the claim correspondence diagram, a shock absorber b interposed between the vehicle body side and each wheel side and capable of changing the damping coefficient by the damping coefficient changing means a, and a sprung part on each wheel of the vehicle
A sprung vertical speed detecting means for detecting the vertical speed
A bounce component detecting means c for detecting a bounce component included in the sprung vertical speed,
A pitch component detecting means d for detecting the Murrell pitch component,
A roll component detecting means e for detecting a roll component included in the detected sprung vertical speed, and corresponding to the vertical movement of the vehicle,
At least pitch damping coefficient of the shock absorber for the front wheel, the controlled based on the front-wheel control signal obtained by the detection component comprising at least bounce component, while the damping coefficient of the shock absorber on the rear wheel side, with the exception of bounce component And a damping coefficient control means for controlling based on a rear wheel control signal obtained from the detection component including one of a component and a roll component.

The front-wheel control signal is obtained from a bounce component and a roll component of each detected component.
The rear wheel control signal may be obtained from a pitch component and a roll component of each detection component.

[0009]

When each component is detected by each of the bounce component detection means, the pitch component detection means, and the roll component detection means, the damping coefficient control means firstly executes the front wheel based on at least the component including the bounce component among the detected components. The control signal for the rear wheel is obtained, the bounce component is removed from the detection components, and the control signal for the rear wheel is obtained based on at least one of the pitch component and the roll component. Then, the damping coefficient of the front wheel side shock absorber is controlled according to the front wheel control signal, and the damping coefficient of the rear wheel side shock absorber is controlled according to the rear wheel control signal.

Therefore, on the front wheel side, control is performed to suppress the bouncing of the vehicle body at least corresponding to the bounce. As a result, the vertical movement of the vehicle body in front of the driver's line of sight can be suppressed, and the bounce of the entire vehicle body can be suppressed, thereby improving the steering stability and ride comfort. on the other hand,
On the rear wheel side, at least control for suppressing the pitch or roll is performed, that is, by suppressing the pitch or roll behind the driver, the pitch or roll of the entire vehicle body can be suppressed.

That is, in general, a bounce is more likely to occur on the front side, and it is more effective to suppress the bounce on the front side than on the rear side of the driver's line of sight. Pitching is easy, and pitching can be suppressed by controlling one of the front and rear movements of the vehicle body. Therefore, the bounce and pitch or roll of the entire vehicle body can be suppressed by the above-described control.

Further, as described above, by making the main subject of control different between the front wheel side and the rear wheel side, control can be simplified as compared with performing control including all components in each shock absorber. In addition to this, it is easy to perform control tuning corresponding to each of the bounce characteristics, pitch characteristics, and roll characteristics, and it is possible to suppress a sudden change in the attenuation characteristic by reducing a sudden change in the attenuation coefficient.

[0013]

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

FIG. 2 is an explanatory view showing the structure of a vehicle suspension system according to an embodiment of the present invention, in which four shock absorbers SA are interposed between a vehicle body and four wheels.
₁ , SA ₂ , SA ₃ , SA ₄ (in describing the shock absorber, these four are collectively referred to, and when describing their common configuration, they are simply indicated as SA). ing. A vertical acceleration sensor (hereinafter referred to as a vertical acceleration sensor) for detecting an acceleration in the vertical direction is provided on the vehicle body near each shock absorber SA.
A sensor 1) is provided. At a position near the driver's seat, there is provided a control unit 4 that receives a signal from each sensor 1 and outputs a drive control signal to the pulse motor 3 of each shock absorber SA.

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. A signal is input. The interface circuit 4
In FIG. 14A, one set of five filter circuits shown in FIG. That is, LPF
Reference numeral 1 denotes a low-pass filter circuit for removing noise in a high frequency range (30 Hz or more) from signals sent from the upper and lower G sensors 1. LPF2 is a low-pass filter circuit L
This is a low-pass filter circuit for integrating a signal indicating acceleration that has passed through PF1 and converting the signal into a sprung vertical velocity.
BPF1 passes the frequency range including the sprung resonance frequency bouncing component signal _{v (v 1, v 2,} v 3, v 4 Numerals _{1, 2, 3 and 4} to the position of the shock absorbers SA (The same applies to the following.) The BPF 2 allows the pitch component signal v ′ to pass through a frequency range including the pitch resonance frequency.
(V ₁ ′, v ₂ ′, v ₃ ′, v ₄ ′). The BPF 3 allows the roll component signal v ″ (v
_{1 ", v 2", v} 3 ", v 4") is a band-pass filter circuit forming the. In this embodiment, the case where the sprung resonance, the pitch resonance, and the roll resonance have different frequencies is taken as an example. However, when these resonance frequencies are close to each other, only the BPF1 may be used as the bandpass filter.

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 formed therein, 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. Reference numeral 38 in the figure denotes a retainer on which the pressure side check valve 22 is seated.

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

Therefore, between the upper chamber A and the lower chamber B, as a flow path through which fluid can flow during the extension stroke, the inside of the extension side damping valve 12 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
PF1, LPF2, BPF1, BPF2, and BPF3 perform a process of obtaining a bounce component signal v, a pitch component signal v ', and a roll component signal v ". These signals v, v', and v" are respectively , Bounce component,
Since the pitch component and the roll component are shown, the portion for obtaining these signals in the control unit 4 and the upper and lower G sensor 1 constitute a bounce component detector, a pitch component detector, and a roll component detector of the claims. I have.

Step 102 uses the following equation (1).
The front-wheel control signal V is determined based on the component signals v, v ', and v ".
_{In this step, F1} and _VF2 and the rear wheel control signals _VR3 and _VR4 are calculated. Note that these control signals V _F1 , V _F2 , V
_{When R3} and _VR4 are displayed collectively, V is displayed.

[0025]

(Equation 1) α _f is the bounce coefficient of the front wheel γ _f is the roll coefficient of the front wheel β _r is the pitch coefficient of the rear wheel γ _r is the roll coefficient of the rear wheel v ₁ , v ₁ ′, v ₁ ″: sprung front right wheel Vertical speed signal v ₂ , v ₂ ′, v ₂ ″: front wheel left sprung vertical speed signal v ₃ , v ₃ ′, v ₃ ″: rear wheel right sprung vertical speed signal v ₄ , v ₄ ', V ₄ ": a sprung vertical speed signal on the left rear wheel. Also, in each equation, the part enclosed by the first α is a bounce rate indicating a bounce degree obtained by multiplying a predetermined bounce coefficient set according to the resonance frequency characteristic of the vehicle body, and the part enclosed by β Is a pitch rate indicating a pitch degree obtained by multiplying a predetermined pitch coefficient set according to the resonance frequency characteristic of the vehicle body, and a portion enclosed by γ is a roll coefficient set according to the resonance frequency characteristic of the vehicle body. This is a roll rate indicating the degree of roll obtained by multiplication.

[0026] Step 103, the control signal V corresponding to the shock absorbers SA is a step equal to or larger than a predetermined threshold value [delta] _T, the process proceeds to step 104 in YES, a step in NO Proceed to 105.

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

[0028] Step 105, the control signal V is determining whether a value between 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.

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 convenience. If NO is determined in steps 103 and 105, each control signal V is equal to or less than a predetermined threshold value -δ _C. , And proceed 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 sprung vertical speed changes as shown by the control signal V in this figure, as shown in the figure, the control signal V
Is between the predetermined threshold values δ _T and −δ _C , the shock absorber SA is controlled to the soft region SS.

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

When the control signal V becomes equal to or smaller 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. At this time, the damping coefficient C is C = −k ·
V is controlled.

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

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

In performing the above control,
In the embodiment, the front wheel side shock absorbers SA ₁ ,
In SA _2, bounce component and the front-wheel control signal V _F1 calculated by the roll component, by using a V _F2, performs control to suppress the bounce and roll, the shock absorber SA ₃ on the rear wheel side, the SA _4, the pitch component The control for suppressing the pitch and the roll is performed using the rear wheel control signals V _R3 and V _R4 obtained from the roll components.
As described above, in each shock absorber SA, control is performed mainly on bounce suppression on the front wheel side, and pitch and roll are not controlled on the front wheel side, instead of controlling the bounce, pitch, and roll components. Since the control is performed as the main subject, the control can be simplified in spite of performing the control corresponding to all of the bounce, pitch, and roll. Can be suppressed.

In the embodiment, when one of the expansion and the compression is controlled to have a high damping coefficient, the other is fixed to have a low damping coefficient. Therefore, a road surface input reverse to the vibration damping direction is transmitted to the vehicle body. And increase the ride comfort during high damping coefficient control, and reduce the damping when switching from the high damping to the low damping on the compression side, or vice versa. There is no need to change the coefficient characteristics, and this also has the effect of reducing the sudden change control of the damping coefficient and suppressing the occurrence of oil hammer.

In performing the above control,
Since only the upper and lower G sensors 1 are used as sensors, the number of parts can be reduced to reduce cost,
The effect of reducing the time and labor for assembling, assembling space, and weight can be obtained.

In obtaining the bounce rate, pitch rate, and roll rate, different coefficients 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.

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

For example, in the embodiment, the front wheel control signal is obtained from the bounce rate obtained from the bounce component and the roll rate obtained from the roll component. However, the control signal for the front wheel may be obtained from at least the bounce component. It may be determined from only the component, a component obtained by combining the bounce component and the pitch component, or a component obtained by combining all components. Further, although the example in which the rear wheel control signal is obtained from the roll rate and the pitch rate is shown, the control signal for the rear wheel may be obtained from either the roll component or the pitch component, excluding the bounce component.

In the embodiment, when each control signal does not exceed a predetermined threshold value, an example is shown in which the expansion / compression low attenuation coefficient is controlled to a soft characteristic. The control may be performed to a moderate damping coefficient. In this case, the steering stability is improved as compared with the embodiment.

In the embodiment, the bounce component detecting means, the pitch component detecting means, and the roll component detecting means are
Although the one using the upper and lower G sensors and the part operated by the controller is shown, the detecting means may be a detecting means for detecting the vehicle height at each position of the four wheels of the vehicle, or the relative speed between sprung and unsprung it may pressurized forte means for detecting.

In this embodiment, the shock absorber has a structure in which one of the extension and the pressure has a high damping coefficient and the other has a low damping coefficient. Or a known structure having a low attenuation coefficient may be used.

[0047]

As described above, the vehicle suspension system according to the present invention detects the bounce component, the pitch component, and the roll component, and based on the front wheel control signal obtained from at least the component including the bounce component, controls the front wheel side. While controlling the damping coefficient of the shock absorber, the damping coefficient of the rear wheel side shock absorber is controlled based on the rear wheel control signal obtained by removing the bounce component and obtaining at least one of the pitch component and the roll component. Because it was configured to
Not only bounce, but also sufficient control force for pitch and roll can be obtained, which has the effect of improving ride comfort and steering stability. By making the control subject different from that on the side, control can be simplified as compared to performing control including all components in each shock absorber, and each characteristic of bounce characteristics, pitch characteristics, and roll characteristics can be improved. The corresponding control can be easily tuned, and an abrupt change in the damping coefficient can be reduced to suppress an abrupt change in the damping characteristic.

[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 an explanatory diagram illustrating a configuration of a vehicle suspension device according to an embodiment of the present invention.

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

FIG. 4 is a cross-sectional view showing a shock absorber applied to the 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 embodiment.

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

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

[Explanation of symbols]

 a damping coefficient changing means b shock absorber c bounce component detecting means d pitch component detecting means e roll component detecting means f damping coefficient controlling means

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Makoto Kimura 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Atsugi Unisia Co., Ltd. (72) Inventor Shinobu Kakizaki 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Atsugi Unisia Co., Ltd. (72) Inventor Fumiyuki Yamaoka 1370 Onna, Atsugi City, Kanagawa Prefecture Inside Atsugi Unisia Co., Ltd. (56) References JP-A-2-141317 (JP, A) JP-A-3-276807 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B60G 17/015

Claims (2)

(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 a sprung vertical speed detecting a sprung vertical speed on each wheel of the vehicle.
Degree detecting means, bounce component detecting means for detecting a bounce component included in the detected sprung vertical speed, pitch component detecting means for detecting a pitch component included in the detected sprung vertical speed, and detected sprung vertical and a roll component detecting means for detecting a roll component contained in the speed, in response to vertical movement of the vehicle, the damping coefficient of the shock absorber of the front wheel side, determined by the detection <br/> component comprising at least bounce component wheel On the other hand, the damping coefficient of the shock absorber on the rear wheel side is controlled based on the rear wheel control signal obtained from the detected component including at least one of the pitch component and the roll component, excluding the bounce component. And a damping coefficient control means. 2. The control signal for the front wheel is determined by a bounce component and a roll component of each detected component, while the control signal for the rear wheel is determined by a pitch component and a roll component of each detected component. The vehicle suspension according to claim 1, wherein