JP2603386Y2 - 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 for optimally controlling a damping coefficient of a shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension system for performing optimal control of a damping coefficient, for example, a vehicle suspension system described in Japanese Utility Model Laid-Open Publication No. 63-93203 is known.

[0003] This conventional device is based on the Skyhook theory, in which the higher the frequency of the input from the road surface, the lower the transmission rate to the body, so that the damping force increases and decreases in proportion to the speed in the vertical direction of the body. Control is performed.

[0004]

However, in the above-described conventional apparatus, when a road surface input near the unsprung resonance point is input as a main input component, the damping force of the shock absorber is controlled to be almost in a soft state. As a result, the unsprung “flapping” becomes large, and the ride quality and the tire contact property deteriorate.

The present invention has been made in view of the above-mentioned conventional problems, and provides a vehicle suspension system capable of suppressing unsprung "fluttering" and improving ride comfort and tire contact properties. It is intended to be.

[0006]

Therefore, according to the present invention, the sprung vertical speed of the frequency band including the sprung resonance frequency is within a predetermined threshold value, and the sprung frequency of the frequency band including the unsprung resonance frequency is sprung. When the vertical acceleration is greater than or equal to a predetermined threshold,
The above object is achieved by setting the damping coefficient higher than usual. That is, as shown in the claim correspondence diagram of FIG. 1, the present invention includes a shock absorber b interposed between the vehicle body side and each wheel side and formed so that a plurality of damping coefficients can be changed by damping coefficient changing means a. A vehicle behavior detecting means e for detecting vehicle behavior including sprung vertical velocity detecting means c for detecting sprung vertical velocity and sprung vertical acceleration detecting means d for detecting sprung vertical acceleration ; Depending on the direction of the vertical speed, the sprung vertical speed
When facing upward, the damping coefficient on the extension side depends on the sprung vertical speed.
On the other hand, when the sprung vertical speed is downward,
And a damping coefficient control means f for performing a normal control for controlling the damping coefficient according to the sprung vertical velocity . The damping coefficient controlling means f has a predetermined sprung vertical velocity near the sprung resonance frequency band. When the sprung vertical acceleration in the vicinity of the unsprung resonance frequency band is equal to or greater than a predetermined threshold value, a correction unit g that performs a correction control that increases the damping coefficient to be larger than the damping coefficient controlled by the normal control is provided. Configuration.

That is, as shown in the claim correspondence diagram of FIG. 1, the present invention provides a shock absorber interposed between the vehicle body side and each wheel side and formed so that a plurality of damping coefficients can be changed by damping coefficient changing means a. b, a sprung vertical speed detecting means c for detecting a sprung vertical speed, and a sprung vertical acceleration detecting means d for detecting a sprung vertical acceleration, and a vehicle behavior detecting means e for detecting a vehicle behavior. And damping coefficient control means f for performing a normal control for controlling the damping coefficient to a predetermined damping coefficient according to the vehicle behavior. The damping coefficient control means f has a predetermined sprung vertical speed near the sprung resonance frequency band. If the value is equal to or less than the predetermined value and the sprung vertical acceleration in the vicinity of the unsprung resonance frequency band is equal to or greater than a predetermined threshold, a compensation control for increasing the damping coefficient to be higher than the damping coefficient controlled by the normal control is performed. Part g is a configuration that is provided.

[0008]

When a road surface input near a high-frequency unsprung resonance frequency is input as a main input component, the transmission rate to the body decreases and the sprung vertical speed decreases.

In this manner, when the sprung vertical speed is reduced to a predetermined threshold value or less and the road surface input is an input that causes "fluttering" under the sprung, the sprung vertical acceleration is reduced. Above a certain threshold, and as a result,
The correction unit of the damping coefficient control unit performs a correction control for correcting the damping coefficient higher than usual.

[0010] Accordingly, the unsprung "flutter" is suppressed, and the ride quality and the tire contact property are improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. First, the configuration of the vehicle suspension device according to the embodiment of the present invention will be described.

FIG. 2 is a structural explanatory view showing a vehicle suspension system according to an embodiment of the present invention. The shock absorbers SA _FR , SA _FR on the front wheel side and the rear wheel side are interposed between the vehicle body and each wheel. Shock absorbers SA _RR and SA _RR are provided. A vertical acceleration sensor (hereinafter, referred to as a vertical G sensor) 1 for detecting a vertical acceleration is provided on the vehicle body near the position where each of the shock absorbers SA _FR and SA _RR is attached to the vehicle body. At a position near the driver's seat, there is provided a control unit 4 which receives a signal from the upper and lower G sensors 1 and outputs a drive control signal to the pulse motor 3 of each of the shock absorbers SA _FR and SA _RR .

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 vertical acceleration is detected as a positive value for upward acceleration and a negative value for downward acceleration. The interface circuit 4a includes an integrating circuit for integrating signals from the upper and lower G sensors 1 and an upper and lower G sensor.
A band-pass filter that passes only a signal in a predetermined frequency range including the unsprung resonance frequency among the signals from the sensor 1 and a signal in a predetermined frequency range including the sprung resonance frequency among the integrated signals. And a band-pass filter for passing therethrough.

Next, FIG. 4 shows each shock absorber SA.
One configuration of _FR and SA _RR (each shock absorber S
A cross-sectional view illustrating the A _FR, construction of SA _RR are the same), the shock absorber SA (hereinafter, the shock absorbers SA _FR, when referring to any one of the SA _RR is a simply SA (Shown) is a cylinder 30 and a piston 3 defining the cylinder 30 in an upper chamber A and a lower chamber B.
1, an outer cylinder 33 having a reservoir chamber 32 formed on the outer periphery of the cylinder 30, a base 34 defining a lower chamber B and the reservoir chamber 32, and a guide for sliding the piston rod 7 connected to the piston 32. Guide member 35, suspension spring 36 interposed between outer cylinder 33 and the vehicle body
And a bumper bar 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 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 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 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, the adjuster 40 is rotated in the counterclockwise direction from a position where both the extension side and the compression side have a low damping coefficient (the position in the figure is referred to as a soft characteristic SS). Then, only the extension side changes the attenuation coefficient to the high attenuation side in multiple stages (this area is referred to as the extension side hard characteristic HS). Conversely, when the adjuster 40 is rotated clockwise, only the compression side has a high attenuation coefficient. The structure changes in multiple stages to the side (this region is referred to as a compression side hard characteristic SH).

Incidentally, in FIG. 7, the adjuster 40 is set at (the position at which the maximum damping coefficient is attained by the expansion-side hard characteristic HS), (the position at which the soft characteristic SS is attained), and (at the position at which the maximum attenuation coefficient is attained at the compression-side hard characteristic SH). The KK section, the MM section, and the NN section in FIG. 5 when arranged at three positions are shown in FIGS. 8, 9, and 10, respectively, and the damping force characteristics at each position are shown. This is shown in FIGS.

Next, the operation of the control unit 4 for controlling the driving of the pulse motor 3 will be described with reference to the flowchart of FIG.

Step 101 is a step of reading the detected sprung vertical acceleration G from each of the vertical G sensors 1.

[0022] Step 102 is a step for performing an operation by integrating the sprung acceleration G Request vertical velocity V _n sprung. As described above, the sprung vertical velocity Vn is _equal to the vertical acceleration G
Therefore, a portion of the vertical G sensor 1 and the control unit 4 that performs this integration constitutes a sprung vertical speed detecting means as claimed.

[0023] Step 103, the vertical sprung mass velocity V _n is the step of determining whether a first threshold value [delta] ₁ below, the process proceeds to step 104 NO, the process proceeds to step 105 in YES.

[0024] Step 104 is a processing step for determining a target damping coefficient DF by the normal control, the A normal control, what determines the damping coefficient in proportion to the sprung mass vertical velocity V _n for each position, That is, the sprung vertical velocity V _n
If upward, in proportion to the velocity V _n, changing the damping coefficient of extension side using the entire area of the extension side hard characteristic HS of ~ 7, whereas, the vertical sprung mass velocity V _n is a downward if, in proportion to the velocity V _n is changed to the attenuation coefficient of the pressure side by using the entire area of the compression side hard characteristic SH in ~ in the figure,
A controls the damping coefficient of the shock absorber SA for each position, the target damping coefficient DF which is determined by the normal control are expressed in α · V _n.

In step 105, the sprung acceleration G is set to the second
A step of determining whether a threshold value [delta] ₂ or more, the process proceeds to step 106 YES, the process proceeds to step 104 if NO.

Step 106 is a step of making a correction to increase the target damping coefficient DF. In this step,
The coefficient of the target damping coefficient DF is changed to the target damping coefficient D of the normal control.
The coefficient is increased as a coefficient (α + β) obtained by adding β to α of F, that is, the target damping coefficient DF = (α + β) · V _n
And

[0027] Step 107 is a step of determining whether the sign of the sprung mass vertical velocity V _n is inverted, the process returns to step 106 NO, a completed one flow YES.

Next, the operation of the embodiment will be described with reference to the time chart of FIG.

[0029] In the region of figure I, the absolute value of the sprung mass vertical velocity V _n is has a first threshold value [delta] ₁ or less, the absolute value of the sprung mass vertical acceleration G is, the second threshold since less than [delta] _2, the flow chart of steps 103～105～1
In step 04, normal control is performed. As a result, the attenuation coefficient is proportional to the sprung mass vertical velocity V _n as shown.

Thereafter, when the absolute value of the sprung vertical acceleration G becomes equal to or larger than the second threshold value δ ₂ as shown in a region II in the drawing,
While the process is being performed (extending process in the figure), correction control is performed (the flow of steps 103 to 105 to 106 to 107).

As a result, the damping coefficient becomes higher than that of the normal control indicated by N in the figure.

That is, as described above, the sprung vertical velocity V _n
Is low, and the sprung vertical acceleration G is high when the road surface input whose main component is in the vicinity of the unsprung resonance frequency is large, and if the damping coefficient remains low as in normal control, Although "fluttering" occurs under the spring, in the present embodiment, as shown by C in the figure, since the correction is made to a high damping coefficient, this "fluttering" is suppressed, and the riding comfort and the tire contact property are improved. I do.

Next, in region III, the sprung vertical velocity V _n
Is reversed, the correction control is released, and the control returns to the normal control.

[0034] Next, in the region IV, again, in a state the absolute value of the sprung mass vertical velocity V _n is the first threshold value [delta] ₁ or less, the absolute value of the sprung mass vertical acceleration G is a second threshold value [delta] _Since it has become ₂ or more, the correction control is restarted and the damping coefficient is controlled to be higher than that of the normal control.

[0035] As described above, in this embodiment, based on the vertical velocity V _n and sprung mass vertical acceleration G spring, in a situation where the unsprung "flutter" occurs, this to accurately detect and high damping coefficient It has the characteristic that the ride comfort and the tire contact property can be improved by correcting and suppressing "fluttering".

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

For example, in the embodiment, the normal control is controlled only in accordance with the sprung vertical speed, but as in the conventional case, the damping coefficient is determined based on the sprung vertical speed and the sprung-unsprung relative speed. May be determined.

Further, in the embodiment, when the correction control, when performing correction to increase the damping coefficient, the coefficient applied to the sprung mass vertical velocity V _n, an example in which so as to increase the alpha of the normal control to the (alpha + beta) Although shown, a constant number may be added to increase the attenuation coefficient, such as αV _n + β.

[0039]

As described above, according to the vehicle suspension system of the present invention, the damping coefficient control means controls the sprung vertical speed near the sprung resonance frequency band to be lower than a predetermined threshold value and the unsprung resonance frequency. When the sprung vertical acceleration in the vicinity of the band is equal to or greater than a predetermined threshold value, a correction unit is provided for increasing the damping coefficient to be higher than the damping coefficient controlled by the normal control. When the input is input as the main input component, the correction unit controls the damping coefficient to be higher than normal, thereby suppressing unsprung “fluttering” due to road surface input, and improving ride comfort and tires. The effect that the grounding property can be improved can be obtained.

[Brief description of the drawings]

FIG. 1 is a conceptual view of a vehicle suspension device according to the present invention.

FIG. 2 is an explanatory view showing the configuration of the vehicle suspension device according to the 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 flowchart showing the operation of the control unit of the embodiment device.

FIG. 15 is a time chart showing the operation of the embodiment device.

[Explanation of symbols]

 a damping coefficient changing means b shock absorber c sprung vertical speed detecting means d sprung vertical acceleration detecting means e vehicle behavior detecting means f damping coefficient controlling means g correction section

Claims (1)

(57) [Scope of request for utility model registration] 1. A shock absorber interposed between a vehicle body side and each wheel side, wherein a plurality of damping coefficients can be changed by damping coefficient changing means, a sprung vertical speed detecting means for detecting a sprung vertical speed, and comprises sprung mass vertical acceleration detecting means for detecting a sprung mass vertical acceleration, and a vehicle behavior detection means for detecting a vehicle behavior, in the normal, depending on the direction of the sprung mass vertical velocity, sprung vertical
When the speed is upward, the damping coefficient on the extension side
On the other hand, when the sprung vertical speed is downward
Comprises damping coefficient control means for performing normal control for controlling the compression side damping coefficient in accordance with the sprung vertical velocity , wherein the damping coefficient controlling means has a predetermined sprung vertical velocity near the sprung resonance frequency band. When the sprung vertical acceleration in the vicinity of the unsprung resonance frequency band is equal to or larger than a predetermined threshold value, a correction unit that performs a correction control that increases the damping coefficient to be higher than the damping coefficient controlled by the normal control is provided. A vehicle suspension device comprising: