JPH0569717A - Vehicle suspension - Google Patents

Abstract

PURPOSE:To provide a vehicle suspension by which such parallel roll as that the roll angle of a front wheel is the same as that of a rear wheel is not generated, but such diagonal roll as that the turning outer wheel of the front wheel is most settled down and can roll on a diagonal line is generated in the case of rolling of vehicles and such inconvenience as aggravation of comfortable ride in straight running and the drop down of steering ability and the like is not generated. CONSTITUTION:A shock absorber 1 installed between the wheels and the body of vehicles and formed its attenuation coefficient changeably, a steering sensor 5a detecting that the vehicle stays in a roll status and a controller 2 which can carry out a roll control for raising up an attenuation power during roll detection by delaying the shock absorber on the turning outer wheel side of the front wheel by a prescribed hour in relation to the shock absorber on the turning outer wheel side of the rear wheel are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension system for a vehicle, and more particularly, to a suspension system having a variable damping coefficient.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension system having a shock absorber with a variable damping coefficient, for example, Japanese Patent Publication No. 59-
The one described in Japanese Patent No. 100064 is known.

This conventional device is a suspension device capable of simultaneously switching at least one of a damping force or a spring constant of a shock absorber by a signal from each sensor, a suspension device, and a steering property corresponding thereto. It is equipped with a controller that makes changes.

Therefore, when the roll condition is calculated by each sensor, the damping force of the shock absorber is increased simultaneously for all the wheels to stabilize the posture and improve the steering stability.

[0005]

However, the above-mentioned conventional device has the following problems because it is configured to increase the damping force of the shock absorbers of all the wheels.

That is, in general, regarding the roll posture,
A diagonal roll that rolls on the diagonal with the outer turning wheel of the front wheel sinking the first is smaller than a parallel roll that has the same roll angle in the front and rear of the vehicle because it uses the spring rigidity of the vehicle to roll. Tends to. However, as described above, if the damping force is increased at the same time for all the wheels, the rolls become parallel rolls and the roll angle becomes large.

Therefore, the suspension systems used so far are
Tuning is performed so that the front and rear wheels have a damping force characteristic so that a diagonal roll is achieved, but along with that, deterioration of the riding comfort when driving straight, deterioration of steering stability, etc. appear, which is the best setting for various vehicle behaviors. Was very difficult.

The present invention has been made by paying attention to the above problems. Therefore, when the vehicle rolls, the front outer wheel of the turning wheel sinks first and the rear inner wheel of the turning wheel rises the highest on a diagonal line. It is an object of the present invention to provide a vehicle suspension device capable of causing a diagonal roll that does not occur, and that does not cause problems such as deterioration of riding comfort when driving straight ahead and deterioration of steering stability.

[0009]

In order to achieve the above object, the vehicle suspension system of the present invention comprises a shock absorber which is provided between a vehicle wheel and a vehicle body and whose damping coefficient is changeable. , A roll detecting means for detecting that the vehicle is in a rolling state, and at the time of roll detection, the shock absorber on the turning outer wheel side of the front wheel is delayed by a predetermined time with respect to the shock absorber on the turning outer wheel side of the rear wheel to reduce the damping force. And a roll control means for performing roll control for increasing the temperature.

[0010]

When the roll is detected, the roll control means controls the shock absorber to a high damping coefficient by the roll control to suppress the roll. During this roll control, the high damping control timing for the shock absorber on the turning outer wheel side of the front wheels is delayed by a predetermined time from the high damping control timing for the shock absorber on the turning outer wheel side of the rear wheels.

Therefore, the front wheel side of the turning outer wheel is delayed by the delay time as compared with the rear wheel side, and the roll-out effect is delayed. Then, a diagonal roll that rolls on a diagonal line occurs instead of a parallel roll having the same roll angle in the front and rear.

[0012]

Embodiments of the present invention will be described with reference to the drawings.

First, the structure of the vehicle suspension system according to the first embodiment of the present invention will be described.

FIG. 1 is a vehicle suspension system 1 according to a first embodiment of the present invention.
1 is a general view showing a shock absorber. The shock absorber 1 is provided between each of the four wheels and the vehicle body, and is formed so that the damping coefficient can be changed based on the driving of the step motor 3 controlled by the controller 2. Further, the controller 2 uses the steering sensor 5a, the vehicle speed sensor 5b, the accelerator sensor 5c, and the brake sensor 5 as input means.
d, a lateral G sensor 5e, and a load sensor 5f.
The load sensors 5f are provided at the mounting portions of the shock absorbers 1 on the vehicle body, and the other sensors are
It is attached to the car body.

Next, the structure of the shock absorber 1 will be briefly described with reference to FIGS. 2 and 3. Both figures are sectional views of one shock absorber 1 by superimposing the S-S line.

The shock absorber 1 is a so-called inverted type in which the piston rod 11 is supported on the wheel side and the cylinder 12 side is supported on the vehicle body. That is,
The shock absorber 1 is doubled by an inner cylinder 12a and an outer cylinder 12b, the upper ends of both cylinders 12a and 12b are closed by a valve body 13, and the lower ends are closed by a guide member 14 and a seal member 15. An outer liquid chamber C is formed between the cylinders 12a and 12b. Then, the inside of the inner cylinder 12a is fixed to the upper chamber A by the piston 17 fixed to the upper end of the piston rod 11.
And the lower chamber B. The lower chamber B and the outer liquid chamber C are communicated with each other by a communication groove 14a formed in the guide member 14.

An outer cylinder 18 is provided outside the cylinders 12a and 12b, and a reservoir chamber D is formed outside the outer cylinder 12b and the valve body 13.
The step motor 3 is provided on the inner circumference of the upper end of the outer cylinder 18.
Is housed.

An eye 11a is fixed to the lower end of the piston rod 11, and a cover cylinder 19 that covers the outer circumference of the outer cylinder 18 is fixed. A dust boot 20 is provided between the upper end of the cover cylinder 19 and the upper end of the outer cylinder 18.

Next, the structure of the valve body 13 will be described with reference to FIG. 4, which is an enlarged view of the main parts of FIG. That is, the valve body 13 has the first and second inner surfaces that are fitted to each other.
It is formed by the valve body 31 and the second valve body 32, and an intermediate chamber E is formed between them. And the first
The valve body 31 is formed with a first communication hole 31a and a second communication hole 31b that communicate the intermediate chamber E and the reservoir chamber D, and the extension side damping valve 3 is provided on the upper surface by closing the first communication hole 31a.
3 is provided, and a check valve 34 is provided on the lower surface to close the second communication hole 31b. The second valve body 32 has a first communication hole 32a that communicates the intermediate chamber E and the upper chamber A, a second communication hole 32b that communicates the reservoir chamber D and the upper chamber A, and the intermediate chamber E and the outside. A third communication hole 32c that communicates with the liquid chamber C is formed, and a compression side damping valve 35 is provided on the upper surface to close the first communication hole 32a and
A check valve 36 is provided on the lower surface to close the second communication hole 32b.

A support cylinder 37 is provided at the center of the valve body 13 so as to penetrate therethrough, and the ports 37a, 37b,
By the spaces 37c, 37d, 37e and the inner circumference, the extension side damping valve 33 is bypassed to allow the first communication hole 31a to communicate with the reservoir chamber D, and the pressure side damping valve 35 is bypassed. A bypass passage F is formed which allows the first communication hole 32a and the reservoir chamber D or the intermediate chamber E to communicate with each other.

In the support cylinder 37, the communication groove 3
An adjuster 38 having 8a for changing the flow passage cross-sectional area of the bypass F is rotatably mounted. In addition, this adjuster 3
Reference numeral 8 is connected to the step motor 3 and is rotated by driving the step motor 3.

Therefore, when the compression side stroke is performed, the fluid in the upper chamber A opens the compression side damping valve 35 and reaches the intermediate chamber E, and the bypass chamber F, and the reservoir chamber D or the intermediate chamber. It is possible to circulate through the flow path leading to E, and as shown in the damping force characteristic diagram of FIG. 5, the damping coefficient can be changed in five stages according to the rotating position of the adjuster 38. In addition, the number shown at the tip of the line showing the characteristics is the step motor 3
Drive step of the step motor 3 is 1
Drive every 0 steps.

On the other hand, when the extension side stroke is performed, the fluid in the lower chamber B and the outer liquid chamber C communicating with the lower chamber B flows into the intermediate chamber E through the third communication hole 32c, and then the extension side damping valve 3
3 can be opened to flow through the flow path to the reservoir chamber D and the flow path to the reservoir chamber D or the upper chamber A through the bypass path F, and in this case also, as in the pressure side stroke, shown in FIG. As described above, the damping coefficient can be changed in five steps.
As shown in the damping force characteristic diagram of FIG. 5 and the damping coefficient characteristic diagram of FIG. 6, the portion bypassing the extension side damping valve 33 of the bypass F is opened to the maximum and the extension side is controlled to the minimum damping coefficient. In the case of 40 steps), the portion bypassing the compression side damping valve 35 is closed and the compression side is controlled to the maximum damping coefficient, and conversely, the portion bypassing the extension side damping valve 33 is set as 0 step. When the valve is closed to control the expansion side to the maximum damping coefficient, the portion bypassing the compression side damping valve 34 is opened to the maximum and the compression side is controlled to the minimum damping coefficient. If 20 steps are taken, the bypass F
The opening degrees of the portion bypassing the expansion side damping valve 33 and the portion bypassing the compression side damping valve 35 are both medium, and both sides of the pressure expanding similarly have medium damping coefficients.

Incidentally, in FIG. 6, the horizontal axis indicates the drive step of the step motor 3 corresponding to the displacement angle of the adjuster 38. In this figure, H is a hard (highest damping coefficient) characteristic, and M is a medium ( Medium damping coefficient characteristic, S shows soft (minimum damping coefficient) characteristic.

Next, the structure of the controller 2 for controlling the driving of the step motor 3 will be described. As shown in FIG. 1, the controller 2 has interfaces 2a, A
It is composed of a / D conversion circuit 2b, a CPU 2c, and a memory 2d. Then, on the basis of the input signals from the respective sensors 5a to 5f, roll control, scut control, dive control, pitching are performed so that optimum ride comfort, steering stability and vehicle attitude can be obtained with the shock absorber 1 as an optimum damping coefficient. Although control such as control and bounce control is performed, roll control will be described here.

FIG. 7 shows a control flow in the case of roll control. When performing roll control, input signals from the steering sensor 5a, the vehicle speed sensor 5b and the load sensor 5f are used. Then, this roll control is started when the steering angle θ obtained from the steering sensor 5a exceeds a predetermined threshold value θ _A as shown in the time chart of FIG. That is, when it is determined that the steering angle θ has exceeded the predetermined threshold value θ _A as shown in step 102 from the straight traveling state shown in step 101, the routine proceeds to step 103 to start the roll control. Each sensor 5a, 5b, 5
It is assumed that the signal from f has been read in advance.

In step 104, the steering angle θ and the angular velocity dθ /
The control constant δ (x) is set by a function of dt and the vehicle speed V. This control constant δ (x) corresponds to the number of driving steps of the step motor 3 as shown in FIG.

Step 105 is a step of giving a control phase difference τ to the shock absorber 1 on the front wheel side by delaying the shock absorber 1 on the rear wheel side by δt in time (see FIG. 10).

In step 106, a drive control signal is output to the step motor 3. As shown in the operation explanatory view of FIG. 9, the outer shock absorber 1L on the outer wheel side (sinking side) is highly damped on the compression side. In addition to the coefficient, the extension side has a low damping coefficient, and the turning inner wheel side (floating side) shock absorber 1R outputs a control signal in which the compression side has a low damping coefficient and the extension side has a high damping coefficient. still,
When going straight without detecting a roll, both sides of the extension are controlled to a medium damping coefficient.

In step 107, as shown in FIG. 8, the damping force DF detected by the load sensor 5f exceeds the threshold value d in the left-right direction and the steering angle θ of the steering wheel exceeds the threshold value θ _A. It is a step to determine whether or not it exceeds
If YES, the process returns to step 103 to continue the roll control, and if NO, the process returns to the straight running control (step 101). By the way, as shown in FIG. 8, the threshold value d of the damping force DF is obtained by multiplying the maximum value of the damping force DF by a predetermined coefficient.

Next, the operation will be described.

In this embodiment, the damping coefficient of each shock absorber 1 is controlled to a medium damping coefficient on both the extension and compression sides during straight running, and a running characteristic with a high feeling of grounding, excellent maneuverability, and high sportiness is obtained. Be done.

Next, steering is performed to change the steering angle θ of the steering wheel.
When the roll angle exceeds a predetermined threshold value θ _A , roll control is started, a control constant δ (x) is obtained according to the steering angle θ, the angular velocity dθ / dt and the vehicle speed V, and based on this control constant δ (x) , The step motor 3 of the shock absorber 1 is driven by a predetermined step, and as shown in FIG. 9, the shock absorber 1R on the turning outer wheel side is controlled to have a high damping coefficient on the compression side and a low damping coefficient on the extending side, and at the same time The side shock absorber 1L is controlled to have a high damping coefficient on the extension side and a low damping coefficient on the compression side.

At this time, as shown in FIG. 10 which is a time chart showing the step change of the step motor 3 corresponding to the change of the damping coefficient at the time of turning left in the first embodiment, as shown in FIG. As a result (see step 105 in the flowchart of FIG. 7), the rise of the damping force of the front wheel (FR) side shock absorber (RH in the figure indicates the right side LH indicates the left side) and the rear wheel (RR) )
It is delayed by the time δt from the shock absorber on the side (indicated by RH and LH in the figure).

Therefore, the compression stroke side of the shock absorber 1 on the outer turning wheel side is set to a high damping coefficient to suppress the sinking of the vehicle body, while the extension side of the shock absorber 1 on the inner turning wheel side is set to a high damping coefficient. By doing so, lifting of the vehicle body can be suppressed and rolling of the vehicle body can be suppressed. At the same time, as shown in FIG. 10, the rise of the damping force on the front wheel side is delayed, and the sinking suppression effect on the front wheel side is delayed as compared to the rear wheel side. Therefore, the turning outer wheel side of the front wheel is the turning outer wheel side of the rear wheel. It becomes more depressed, and not a parallel roll having the same roll angle in the front and rear of the vehicle body but a diagonal roll that rolls on a diagonal line, the roll angle is suppressed, and high steering stability is obtained.

Further, when the wheel passes through unevenness such as undulations of the road surface during such a turn and the shock absorber 1 operates in both directions of expansion, the side having a high damping coefficient in order to suppress rolls. Since the opposite stroke side is controlled to have a low damping coefficient, the transmissibility is reduced, and the transmission of the road surface input to the vehicle body is suppressed accordingly. Therefore, the deterioration of the riding comfort is suppressed, and the disturbance of the vehicle posture due to the road surface input is suppressed.

Next, a second embodiment of the present invention will be described.

In the second embodiment, the control content of the controller 2 is slightly different from that of the first embodiment, and in step 105 of the flow chart shown in FIG. 7, a process of giving a control phase difference τ to the front wheel side is performed. However, the time for the turning outer wheel of the front wheel and the turning inner wheel of the rear wheel is δt in time.
The process of giving the control phase difference τ is delayed (see FIG. 11).

Therefore, in this second embodiment, as shown in FIG. 11 which is a time chart showing the step change of the step motor 3 corresponding to the change of the damping coefficient at the time of turning left, as shown in FIG. ) Of the shock absorber (RH) and the shock absorber (LH) of the left side of the rear wheel (inner wheel of turning) rises in delay. As a result, the effect of suppressing the sinking of the front wheel on the outer side of the turning and the effect of suppressing the lift of the rear wheel on the inner side of the turning are delayed,
The turning outer wheel side of the front wheel sinks first, and the turning inner wheel side of the rear wheel is 1
It will sink more than your turn, making it an ideal diagonal roll that rolls diagonally.

Although the embodiment has been described above, the specific structure is not limited to this embodiment. For example, in the embodiment, the shock absorber on the outer turning side of the front wheel is damped with a delay of a predetermined time. As a roll control means to increase power, a controller that performs calculation and processing is shown.
Although the control phase difference is given in the processing inside the controller, this roll control means includes, for example, means for transmitting a signal to the actuator (in this case, not only an electric signal but also a hydraulic pressure etc. corresponding to the actuator). It also includes means for transmitting the fluid pressure by means of the above), and the feed speed during this transmission may be changed to delay the time until the target high damping coefficient is reached.

Although a shock absorber having a low damping coefficient when one of the compression forces is controlled to a high damping coefficient is shown, a shock absorber having a high damping coefficient on both sides of the compression force may be used.

Further, while both the extension and compression sides are controlled to have the medium damping coefficient when going straight, a low damping coefficient may be used to improve the riding comfort. In this case, the regulator is
The bypass path is configured so that both the expansion side and compression side damping valves are fully opened in both parts.

[0043]

As described above, in the vehicle suspension system of the present invention, at the time of roll detection, the front shock absorber on the turning outer wheel side is set to the shock absorber on the rear turning outer wheel side for a predetermined time. Since the roll control means for controlling the roll to increase the damping force by delaying the delay is provided, during the roll, the turning outer wheel of the front wheel sinks the first by the control of the roll control means, and a diagonal roll that rolls on the diagonal line occurs. Good rolling characteristics can be obtained.Thus, the pure tuning of the suspension itself in the state where the vehicle suspension system does not control does not need to be a tuning that causes a diagonal roll, and a diagonal roll occurs when rolling. However, it is good that the riding comfort and driving stability are not deteriorated when going straight. An effect that characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is an overall view showing a vehicle suspension device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the upper half of the shock absorber of the first embodiment device.

FIG. 3 is a cross-sectional view showing the lower half of the shock absorber of the first embodiment device.

FIG. 4 is an enlarged cross-sectional view showing a main part of a shock absorber of the first embodiment device.

FIG. 5 is a damping force characteristic diagram corresponding to the piston speed of the shock absorber of the first embodiment device.

FIG. 6 is a damping coefficient characteristic diagram corresponding to the step position of the step motor of the shock absorber of the first embodiment device.

FIG. 7 is a flowchart showing a control flow of the controller of the first embodiment device.

FIG. 8 is a steering angle θ, damping force DF, and
It is a time chart which shows the relationship of the step of a step motor.

FIG. 9 is an operation explanatory view of the first embodiment device when a vehicle body roll occurs.

FIG. 10 is a time chart showing a step change of the step motor corresponding to the change of the damping coefficient at the time of turning left in the first embodiment.

FIG. 11 is a time chart showing a step change of the step motor corresponding to a damping coefficient change at the time of turning left in the second embodiment.

[Explanation of symbols]

 1 Shock absorber 2 Controller (roll control means) 5a Steering sensor (roll detection means)

Claims (1)

[Claims] 1. A shock absorber provided between a wheel of a vehicle and a vehicle body, the damping coefficient of which can be changed, a roll detecting means for detecting that the vehicle is in a roll state, and a front wheel at the time of roll detection. And a roll control means for performing roll control for increasing the damping force by delaying the shock absorber on the turning outer wheel side with respect to the shock absorber on the turning outer wheel side of the rear wheel by a predetermined time. apparatus.