JPH06211023A - Vehicle suspension device - Google Patents

Abstract

PURPOSE:To provide a vehicle suspension device capable of preventing a sudden change of a damping coefficient after the release of roll control so as to secure the riding comfort and maneuvering stability of a vehicle. CONSTITUTION:A vehicle suspension device is provided with a control means (g) having a damping coefficient control part (f) for outputting a changeover signal to an actuator (a) so as to control a shock absorber (c) to an optimum damping coefficient on the basis of a detection signal from a vehicle behavior detecting means (d) when the detection value detected by a steering state detecting means (e) is less than the specified threshold value. The control means (g) is provided with a roll control part (h) for outputting a changeover signal to the actuator (a) so that the stroke side damping coefficient of each shock absorber (c) is changed to be higher only for the specified time when the detection value detected by the steering state detecting means (e) is the specified threshold value or more, and a changeover delay processing part (j) for delaying, only for the specified time, the driving speed of the actuator after the release of roll control performed by the roll control part (h).

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 controlling a damping coefficient of a shock absorber provided between a sprung part and an unsprung part of a vehicle, and more particularly to a device for controlling roll restraint during steering.

[0002]

2. Description of the Related Art Conventionally, as such a vehicle suspension system, for example, one disclosed in Japanese Utility Model Laid-Open No. 59-117510 is known.

This vehicle suspension system controls the shock absorber to have a high damping coefficient when the level is high in accordance with the level of the detected lateral acceleration from the vehicle body lateral acceleration sensor that detects the acceleration applied in the vehicle width direction, and at the same time, Is provided with a control means for switching to a low damping coefficient side for a few seconds after the value falls to a predetermined value, that is, a transient roll of the vehicle body generated due to a sudden steering operation is highly damped by the shock absorber. It was possible to secure the steering stability of the vehicle by suppressing it with a coefficient.

[0004]

However, in such a conventional vehicle suspension system, since the roll control based on the high damping coefficient is released, it is rapidly switched to the low damping coefficient side. There is a problem that both the riding comfort and the driving stability of the vehicle are deteriorated.

The present invention has been made in view of such a problem, and it is possible to prevent a sudden change in the damping coefficient after the roll control is released and to secure the riding comfort and steering stability of the vehicle. It is intended to provide a vehicle suspension system.

[0006]

According to the present invention, as shown in the claim correspondence diagram of FIG. 1, a damping device which is provided between a vehicle body and each wheel and which is actuated by an actuator a to change the damping coefficient is provided. The shock absorber c having the coefficient changing means b, the vehicle behavior detecting means d for detecting a factor relating to the vehicle behavior, the steering state detecting means e for detecting the steering state of the vehicle, and the steering state detecting means e. When the detected value detected is less than a predetermined threshold value, a damping signal that outputs a switching signal to the actuator a to control the shock absorber c to an optimum damping coefficient based on the detection signal from the vehicle behavior detecting means d. When the detection value detected by the steering state detection means e, which is provided in the control means g and the control means g having the coefficient control section f, is equal to or greater than a predetermined threshold value, each of the respective times at that time Shock a A roll control unit h that outputs a switching signal to the actuator a to change the damping coefficient on the stroke side of the saw bar c to a higher level, and a drive speed of the actuator a after the roll control unit h releases the roll control for a predetermined period. And a switching delay processing section j for delaying the delay.

[0007]

The function of the present invention will be described. The reference numerals in the description correspond to those in FIG. When the steering operation is performed while the vehicle is running, the vehicle body rolls. At this time, when the detection value detected by the steering state detecting means e is less than the predetermined threshold value, the roll generated by the steering is also small, so the roll controller h does not operate and the damping coefficient controller At f, a switching signal is output to the actuator a in order to control the shock absorber c to the optimum damping coefficient based on the signal from the vehicle behavior detecting means d, whereby the ride comfort of the vehicle during straight running or steady turning is obtained. And the steering stability is secured.

Further, when the detected value detected by the steering state detecting means e is equal to or larger than a predetermined threshold value, a large amount of roll is generated on the vehicle body by abrupt steering, so the roll control section h Then, a switching signal is output to the actuator a in order to change the damping coefficient on the stroke side of each shock absorber b to a higher value only during a predetermined period, whereby the stroke of each shock absorber b in the roll direction is high. The damping coefficient suppresses the transient roll of the vehicle body.

When the roll control state is released,
The switching delay processing unit j performs processing for making the drive speed of the actuator a slower than usual for a predetermined period of time, whereby the switching from the high damping coefficient side to the low damping coefficient side is performed gently, and therefore the roll control is performed. Deterioration of the riding comfort and steering stability of the vehicle due to a sudden change (decrease) in the damping coefficient after the cancellation is prevented.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, the configuration of the embodiment will be described. FIG. 2 is a system block diagram of an embodiment of the present invention, in which SA is a damping force type shock absorber, 2 is a pulse motor, 3 is a sprung acceleration sensor, 4 is a steering sensor, 5 is a control unit. Shows.

A total of four shock absorbers SA are provided between each of the four wheels and the vehicle body.

The pulse motor 2 switches the damping coefficient position of the shock absorber SA, and changes the damping coefficient position of each shock absorber SA in multiple stages by step driving.

The sprung acceleration sensor 3 is attached to a sprung vehicle body, and detects the vertical acceleration on the spring,
An electric signal corresponding to the detected sprung acceleration is output. The sprung acceleration sensor 3 is also provided for each shock absorber SA.

The steering sensor 4 constitutes a turning state detecting means, is provided in the steering wheel, and outputs an electric signal according to the turning angle. Then, the turning speed is calculated from the change in the turning angle.

The control unit 5 constitutes a control means, and in the damping coefficient control section thereof, based on the input signal from the sprung acceleration sensor 3, the shock absorber SA is set to have an optimum damping coefficient. In addition to outputting a control signal to the motor 2, the roll control section performs control to set the damping coefficient of the shock absorber SA to a high level in order to suppress the roll, and the switching delay processing section further controls the pulse after the roll control is released. A process for reducing the motor 2 drive speed for a predetermined period is performed. That is, the control unit 5 includes an interface circuit 5a, a CPU 5b, and a drive circuit 5c, and the output signals from the vertical acceleration sensor 3 and the steering sensor 4 are input to the interface circuit 5a, respectively.

Next, FIG. 3 is a sectional view showing the structure of the shock absorber SA.
Is a cylinder 30, and the cylinder 30 is an upper chamber and a lower chamber B.
And a piston 31 defined by the outer cylinder 33 having a reservoir chamber C formed on the outer periphery of the cylinder 30, a base 34 defining the lower chamber B and the reservoir chamber C, and a piston rod 7 connected to the piston 31. Member 3 for guiding the sliding of
5, a suspension spring 36 interposed between the outer cylinder 33 and the vehicle body, and a bumper bar 37.

More specifically, as shown in FIG. 4, the shock absorber SA has a groove on the extension side inner side as a flow passage through which the fluid compressed in the upper chamber A in the extension stroke can flow to the lower chamber B side. From the position 11 of the expansion side damping valve 12, the inside and the outer peripheral portion of the expansion side damping valve 12 are opened to reach the lower chamber B through the expansion side first flow path D, the second port 13, the vertical groove 23, and the fourth port 14. Via the expansion side second flow path E, which opens the outer peripheral portion of the expansion side damping valve 12 from the position of the expansion side outer groove 15 to reach the lower chamber B, the second port 13, the vertical groove 23 and the fifth port 16. The extension-side check valve 17 is opened to reach the lower chamber B, and the bypass flow to the lower chamber B via the third port 18, the second lateral hole 25, and the hollow portion 19. There are four flow paths to the path G, and the fluid in the lower chamber B compressed in the pressure stroke flows to the upper chamber A side. As capacity flow path, the compression side damping valve 2
0 to open the pressure side first flow path H to the upper chamber A, and the pressure side check valve 22 to open to the upper chamber A via the hollow portion 19, the first lateral hole 24 and the first port 21. 2nd pressure side
Channel J, hollow 19, second lateral hole 25, and third port 1
3 with the bypass flow path G leading to the upper chamber A via 8
There are two channels.

The vertical groove 23 and the first and second lateral holes 2 are also provided.
The adjuster 6 in which 4, 25 are formed can switch the position of the damping coefficient in multiple stages among the three positions shown in FIGS. 5 to 7 based on the step rotation by the driving of the pulse motor 2. .

First, at the second position shown in FIG. 5 (the position shown in FIG. 8), the expansion side first flow path D, the compression side first flow path H and the compression side second flow path J can flow. As a result, as shown in FIG. 9, the extension side has a high damping coefficient (see FIG.
+ Xmax position), the pressure side of the reverse stroke has a predetermined low damping coefficient (-Xsoft position in FIG. 12).

Next, at the first position shown in FIG. 6 (the position shown in FIG. 8), the four flow passages D in the pressure stroke,
E, F, G and all of the three flow paths H, J, G of the pressure stroke are allowed to flow, and as a result, as shown in FIG. 10, both the expansion side and the compression side have a predetermined low damping coefficient. (± Xsoft position in FIG. 12).

Next, at the third position shown in FIG. 7 (the position shown in FIG. 8), the extension side first to third flow paths D, E, F are provided.
Also, the pressure side first flow path H is allowed to flow, and as a result, as shown in FIG. 11, the pressure side has a high damping coefficient (see FIG. 12).
-Xmax position), the extension side of the reverse stroke has a predetermined low damping coefficient (+ Xsoft position in FIG. 12). The first and third positions can be switched in multiple stages according to the step rotation angle of the adjuster 6, and only the damping coefficient on the high damping coefficient side is proportional to the step rotation angle. Can be changed.

That is, in this shock absorber SA, when the adjuster 6 is rotated, the damping coefficient based on the rotation has characteristics as shown in FIG. 12 on both the expansion side and the compression side. It is configured so that it can be changed in multiple steps within the range of high damping coefficient. Moreover, as shown in FIG. 8, when the adjuster 6 is rotated counterclockwise from the position where the low damping coefficient (± Xsoft position in FIG. 12) is set on both the expansion side and the compression side, only the expansion side has a high damping coefficient. Change to the side and vice versa,
When the adjuster 6 is rotated clockwise, only the compression side changes to the high damping coefficient side.

Next, the operation flow of the damping coefficient position control in the control unit 5 will be described with reference to the flow chart shown in FIG.

First, in step 101, the sprung speeds V _R and V _L on the right and left wheels, respectively calculated from the sprung acceleration, and the turning speed ω calculated from the change in the turning angle are read. After that, the process proceeds to step 102.

Step 102 is the absolute value of the turning speed ± ω.
a step of determining whether or not | ω | exceeds an absolute value | a | of a predetermined threshold value ± a.
If the absolute value of a is less than | a | (NO), step 103
To the absolute value of the predetermined threshold value ± a | a |
If S), go to step 104.

Step 103 is a step for performing basic control of the damping coefficient. That is, in this basic control,
Sprung velocity ± V _R to the maximum damping coefficient ± Xhard position of FIG. 11, after being controlled switching the damping coefficient position in proportion respectively to ± V _L, completes one control flow.

[0027] Step 104 and subsequent steps are steps of performing suppressing roll control roll, in step 104, the sprung speed between the sprung velocity V _L on the right-wheel-side spring rate V _R and the left wheel side The roll speed (R _V = V _R −V _L ) of the vehicle is calculated from the deviation, the timer T is started, and then the routine proceeds to step 105.

This step 105 is a step for judging whether the direction of the roll speed R _V of the vehicle is the left roll direction. When the left roll direction (R _V > 0) (YES), the routine proceeds to step 106 and to the right. The extension side of the wheel and the compression side of the left wheel are switched to the high damping coefficient position shown by the ± Xmax positions in FIG. 12, and the right roll direction (R _V
When <0) (NO), the routine proceeds to step 107, where control is performed to switch the pressure side of the right wheel and the extension side of the left wheel to the high damping coefficient position shown by ± Xmax positions in FIG. 12, and then to step 108. move on.

This step 108 is a step of judging whether or not the time t measured by the timer T exceeds a predetermined roll control time b, and is less than the roll control time b (N
If it is O), the process returns to step 105 to determine the direction of the roll speed R _V of the vehicle, and if the roll control time b or more (YES), the process proceeds to step 109 to switch the damping coefficient position. The driving speed of 2 is changed to the low speed side for a predetermined time h. The roll control time b is set to the time required to converge the roll of the vehicle body by turning back after the first turning.

With the above, one control flow is completed, and the control unit 5 repeats the above control flow.

Next, the operation of the embodiment will be described with reference to FIG. That is, FIG. 14 is a time chart for explaining the operation during traveling of the vehicle, and FIG. 14 (a) shows the right sprung speed V _R ,
The figure (b) is the right wheel damping coefficient switching position, the figure (c) is the left wheel sprung speed _VL , the figure (d) is the left wheel damping coefficient switching position, and the figure (e) is the steering speed ω, Figure (f) shows roll speed R
_V is shown respectively.

(A) At the time of basic control When the absolute value | ω | of the turning speed ± ω does not exceed the absolute value | a | of the predetermined threshold value ± a, the roll generated by the turning is small, It is switched to normal basic control with the ± Xhard position as the maximum damping coefficient, and the stroke side of the shock absorber SA in the same direction as the sprung speed ± V at that time has a high damping coefficient proportional to the sprung speed ± V. Switching control of the damping coefficient position is performed. That is, a) As shown by c in FIG. 14, the absolute value of the turning speed ± ω |
ω | is less than the absolute value | a | of a predetermined threshold value ± a,
And when the direction of the sprung speed V is upward (+),
The second position (the direction of the sprung speed V at that time is the high damping coefficient position proportional to the sprung speed + V on the extension side, and the predetermined low damping coefficient (-Xsoft position) on the opposite compression side (Fig. 8 and the position of FIG. 9).

B) As shown by d in FIG. 14, the steering speed ±
The absolute value of ω | ω | is the absolute value of a predetermined threshold ± a | a |
And the direction of the sprung speed V is downward (-)
, The compression side, which is in the same direction as the direction of the sprung speed V at that time, has a high damping coefficient position proportional to the sprung speed −V, and the opposite expansion side has a predetermined low damping coefficient (+ Xsoft position). Third position (FIG. 8 and FIG. 1)
Switch to the (1 position) side.

Therefore, when the roll generation state is predicted by detecting the turning speed and there is no possibility that the roll will become violent,
That is, during straight running or during steady turning with a slow turning speed, the stroke direction side of the shock absorber SA, which is the same as the direction of the sprung speed ± V at that time, is controlled to an appropriate high damping coefficient proportional to the sprung speed ± V. By doing so, it is possible to appropriately suppress the vibration of the sprung body (vehicle body) to improve the steering stability and the riding comfort, and to reduce the shock absorber SA in the direction opposite to the direction of the sprung speed ± V at that time. By setting a predetermined low damping coefficient on the stroke side, it is possible to absorb road surface input in the direction opposite to the stroke direction during damping control, prevent transmission to the vehicle body, and further improve riding comfort.

(B) During roll control As shown in e and f of FIG. 14, the absolute value of the turning speed ± ω |
When ω | exceeds the absolute value | a | of the predetermined threshold value ± a, the roll generated by abrupt steering becomes excessive, so that the shock absorbers in the same direction as the sprung speed ± V at that time are the same. The travel side of SA is switched to the roll control state by the high damping coefficient at the ± Xmax positions, whereby the transient rolling of the vehicle body is suppressed by the high damping force exceeding the damping force at the ± Xhard positions. Then, the absolute value | ω | of the turning speed ± ω is a predetermined threshold value ± a
Even if it falls below the absolute value of | a |, the steered state continues and a large roll is generated in the opposite direction due to the subsequent turning. This high damping coefficient control state is maintained for the set roll control time b. That is, a) First, as shown in e of FIG. 14, when the steered right turning is performed and the turning speed ω exceeds a predetermined threshold value a, a force for largely rolling the vehicle body to the left is generated. Therefore, in the shock absorber SA on the right wheel side, the extension side, which is the same as the direction of the sprung speed V _R (upward), is switched to the high damping coefficient control of the + Xmax position in order to suppress the lifting of the vehicle body while the left wheel side is actuated. In the shock absorber SA, the pressure side, which is the same as the direction of the sprung mass velocity V _L (downward), is switched to the high damping coefficient control of the −Xmax position in order to suppress the sinking of the vehicle body. The transient roll of is suppressed.

B) Next, as shown in FIG. 14f, when left turning is performed as a sharp turning back of right turning, the absolute value | ω | of the turning speed −ω is a predetermined threshold value. Absolute value of -a
Since a force that greatly rolls the vehicle body to the right exceeds | a | and acts, the roll control state with a high damping coefficient is maintained for the roll control time b including the roll generation time due to the turning steering. . That is, in the shock absorber SA on the left wheel side, the extension side, which is the same as the direction of the sprung speed _VL (upward) in order to suppress the lifting of the vehicle body, is + X.
On the other hand, the shock absorber SA on the right wheel side is switched to the high damping coefficient control for the max position, while the sprung speed V _R of the shock absorber SA on the right wheel side is lowered (downward) in order to suppress the sinking of the vehicle body.
The same pressure side as in (4) is switched to the high damping coefficient control of the -Xmax position, which suppresses the transient roll of the vehicle body to the right due to turning back.

Thus, when the initial turning speed is high, the stroke side at that time is switched to the high damping coefficient side for a predetermined roll control time b, so that the stroke side of each shock absorber SA corresponding to each roll direction is changed. The expansion and contraction speed and the stroke of the vehicle body are suppressed, and thereby, the transient roll of the vehicle body due to a sudden steering operation can be suppressed.

Further, the stroke side of the shock absorber SA in the direction opposite to the direction of the sprung speed ± V at that time is set as a predetermined low damping coefficient to absorb the road surface input in the direction opposite to the stroke direction. The riding comfort during control can be improved.

(C) At the time of returning to the basic control As shown in FIG. 14g, when a predetermined roll control time b elapses, the roll control state by the high damping coefficient is released and the normal control state is restored. During the predetermined time h after the recovery, the switching delay processing unit switches the drive speed of the pulse motor 2 to a speed lower than normal, whereby the switching from the high damping coefficient state to the low damping coefficient side is performed gently. Become.

Therefore, this embodiment is characterized in that it is possible to prevent deterioration of the riding comfort and steering stability of the vehicle due to a rapid change (decrease) in the damping coefficient after the roll control is released.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and there may be a design change or the like within a range not departing from the gist of the present invention. Included in the present invention.

For example, in the embodiment, the case where the turning speed calculated by the turning angle is used as the detection value detected by the turning state detecting means is shown. However, threshold control using the turning angle is performed. You may do it.

Further, in the embodiment, the lapse of time is used as the condition for canceling the roll control, but other conditions, for example, when the sprung speed and the steering speed pass the zero point for a predetermined number of times, or after the zero point has passed. It is possible to set the cancellation condition as the passage of time.

In the embodiment, the lapse of time is set as the operation stop condition of the switching delay processing section, but other conditions, for example, when the damping coefficient passes a predetermined switching point or when the damping coefficient falls to a predetermined damping force value. Etc. can be used as a condition.

Further, in the embodiment, in the basic control of the damping coefficient, the case where the damping coefficient is proportionally controlled according to the sprung speed is shown, but the factor relating to the vehicle behavior which is the basis of the damping coefficient control is arbitrary. Also, as the control method, control by a combination of a plurality of factors and threshold control can be performed.

Further, in the embodiment, when controlling one stroke side of the expansion side and the compression side to the high damping coefficient side, the shock absorber having the structure in which the reverse stroke side thereof has the low damping coefficient is used.
It is possible to use a structure in which both the extension side and the compression side are switched to a low damping coefficient or a high damping direction.

[0047]

As described above, in the vehicle suspension system of the present invention, when the detected value detected by the steered state detecting means is equal to or greater than a predetermined threshold value, each A roll control unit that outputs a switching signal to the actuator to change the damping coefficient on each stroke side of the shock absorber to a higher level, and a switching that slows the drive speed of the actuator for a predetermined period after the roll control unit releases the roll control. By providing the delay processing unit, it is possible to prevent a rapid change in the damping coefficient after the roll control is released, and it is possible to obtain the effect of ensuring the riding comfort and steering stability of the vehicle.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a vehicle suspension device of the present invention.

FIG. 2 is a system block diagram showing a vehicle suspension device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a shock absorber applied to the apparatus of the embodiment.

FIG. 4 is an enlarged sectional view showing a main part of the shock absorber.

5 is a sectional view showing a state of a second position, (a) is a sectional view taken along the line KK of FIG. 4, (b) is a sectional view taken along the line LL of FIG. 4, (c).
FIG. 6 is a sectional view taken along line N-N of FIG. 4.

6 is a sectional view showing a state of the first position, (a) is a sectional view taken along the line KK of FIG. 4, (b) is a sectional view taken along the line LL of FIG. 4, (c).
FIG. 6 is a sectional view taken along line N-N of FIG. 4.

7 is a sectional view showing a state of a third position, (a) is a sectional view taken along the line KK of FIG. 4, (b) is a sectional view taken along the line LL of FIG. 4, (c).
FIG. 6 is a sectional view taken along line N-N of FIG. 4.

FIG. 8 is a diagram showing a damping coefficient switching characteristic of the shock absorber.

FIG. 9 is a characteristic diagram of damping coefficient with respect to piston speed in the second position.

FIG. 10 is a characteristic diagram of damping coefficient with respect to piston speed in the first position.

FIG. 11 is a characteristic diagram of damping coefficient with respect to piston speed in the third position.

FIG. 12 is a variable characteristic diagram of the damping coefficient with respect to the piston speed of the embodiment apparatus.

FIG. 13 is a flowchart showing the operation flow of the control unit of the embodiment apparatus.

FIG. 14 is a time chart for explaining the operation of the embodiment apparatus when the vehicle is traveling.

[Explanation of symbols]

 a actuator b damping means changing means c shock absorber d vehicle behavior detecting means e steering state detecting means f damping coefficient control section g control means h roll control section j switching delay processing section

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[Procedure amendment]

[Submission date] April 20, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (1)

[Claims] 1. A shock absorber, which is provided between a vehicle body and each wheel and has damping coefficient changing means that can be actuated by driving an actuator to change the damping coefficient, and vehicle behavior detection for detecting a factor relating to vehicle behavior. Means, a steering state detecting means for detecting a steering state of the vehicle, and a detection signal from the vehicle behavior detecting means when the detection value detected by the steering state detecting means is less than a predetermined threshold value. The control means having a damping coefficient control section for outputting a switching signal to the actuator for controlling the shock absorber to an optimum damping coefficient based on the above, and the detection value provided in the control means and detected by the steering state detection means When it is above a predetermined threshold value, a switching signal is sent to the actuator to change the damping coefficient on each stroke side of each shock absorber at that time to a higher value for a predetermined time. Roll control section for outputting, and a vehicle suspension system, characterized in that it and a switching delay processing unit to slow only during the driving speed of the actuator after the roll control release of a predetermined by the roll control section.