JP3047480B2 - 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 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.
What is described in 100064 gazette is known.

[0003] This prior art device comprises a suspension device capable of simultaneously switching at least one of a damping force and a spring constant of a shock absorber for all wheels by a signal of each sensor, switching of the suspension characteristics and steering characteristics corresponding thereto. Is provided with a controller that performs the change.

Therefore, when the roll condition is calculated by each sensor, the damping force of the shock absorber is increased at the same time for all wheels, thereby stabilizing the attitude and improving the steering stability.

[0005]

However, in the above-described conventional device, the damping force of the shock absorbers of all the wheels is increased, so that the above-described device has the following problems.

That is, generally, the roll posture is
The diagonal roll, which rolls diagonally with the front outer wheel sunk first, is smaller than the parallel roll, which has the same roll angle before and after the vehicle body, because it rolls using the spring rigidity of the vehicle body, so the roll angle is smaller. There is a tendency. However, as described above, if the damping force is increased at the same time for all wheels, a parallel roll is formed, and the roll angle increases.

Therefore, the conventional suspension system is,
Tuning is performed so as to achieve a diagonal roll based on the damping force characteristics of the front and rear wheels, but with this, the riding comfort deteriorates when driving straight ahead and steering stability decreases. Was very difficult.

The present invention has been made by paying attention to the above-mentioned problem. Therefore, when the vehicle rolls, the outer turning wheel of the front wheel sinks down and the inner turning wheel of the rear wheel rolls up diagonally. It is an object of the present invention to provide a vehicle suspension device that can generate a diagonal roll that does not cause a problem such as deterioration of ride comfort when traveling straight and a decrease in steering stability.

[0009]

In order to achieve the above-mentioned object, a vehicle suspension system according to the present invention is provided between a vehicle wheel and a vehicle body. A shock absorber formed so that the attenuation coefficient can be changed to a low attenuation when the compression side is set to a high attenuation, a roll detection means for detecting that the vehicle is in a roll state, and turning at the time of the roll detection. while increasing the damping coefficient of the pressure side for shock absorbers of the outer ring to increase the damping coefficient of the extension side for the shock absorber of the turning inner wheel, further, thus the damping coefficient of the compression side or extension side
To increase the height, the front wheel of the turning outer wheel and the rear wheel of the turning inner wheel
Wheels are reduced by delaying the rear wheel of the turning outer wheel by a predetermined time.
Roll control means for performing roll control to increase the attenuation coefficient
I did .

[0010]

When a roll is detected, the roll control means increases the damping coefficient on the compression side for the shock absorber of the turning outer wheel by the roll control, while increasing the damping coefficient on the extension side for the shock absorber of the turning inner wheel, thereby increasing the turning outer wheel side. The body is prevented from sinking and the turning inner wheel side is prevented from being lifted, thereby suppressing rolling of the vehicle body.
During the roll control, in order to increase the damping coefficient of the shock absorber of the turning outer wheel, the high damping control timing for the front wheel turning outer wheel side shock absorber is set to be higher than the high damping control timing for the rear wheel turning outer wheel side shock absorber. The time has been delayed.
Also, when executing roll control, the shock
To suppress the roll by increasing the damping coefficient on the extension side of the
The shock absorber of the rear wheel of the turning inner wheel is also
Delay for a predetermined time with respect to the rear wheel shock absorber
To increase the damping coefficient .

Therefore, the turning outer wheel on the front wheel side and inside the turning wheel
Rear wheel side of the wheel is delayed the rolling-restraining effect than the rear wheels of the amount corresponding turning outer of this delay time it occurs pivot correspondingly
Many front wheels of the outer wheel will sink, and
A large number of rear wheels are lifted up, and a diagonal roll that rolls diagonally so that the wheel load of the front turning outer wheel becomes heavy instead of a parallel roll with the same roll angle before and after occurs smoothly in a short time Will be. In addition, during the roll control, the damping side of the shock absorber of the turning outer wheel and the pressure side of the shock absorber of the turning inner wheel, which are on the stroke side opposite to the side where the high damping coefficient is controlled to suppress the roll, are low. Coefficient. Therefore, during the roll control, when the vehicle passes through the unevenness of the road surface, the road surface input in the stroke direction having such a low damping coefficient is absorbed without being transmitted to the vehicle body,
Deterioration of riding comfort due to the road surface input and disturbance of the vehicle attitude are suppressed.

[0012]

An embodiment of the present invention will be described with reference to the drawings. First described the structure of the vehicle suspension system of the present onset AkiraMinoru施例. Figure 1 is a general view showing a vehicle suspension device 1 of the present onset AkiraMinoru施例, reference numeral 1 denotes the 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 a step motor 3 controlled by the controller 2. Also, the controller 2
Steering sensor 5a, vehicle speed sensor 5 as input means
b, an accelerator sensor 5c, a brake sensor 5d, a lateral G sensor 5e, and a load sensor 5f. Note that the load sensors 5f are respectively provided at portions where the respective shock absorbers 1 are mounted on the vehicle body, and the other sensors are mounted on the vehicle body.

Next, the structure of the shock absorber 1 will be briefly described with reference to FIGS. Both figures are cross-sectional views of one shock absorber 1 with the SS line superimposed.

The shock absorber 1 is a so-called inverted type in which a piston rod 11 is supported on a wheel side and a cylinder 12 is supported on a vehicle body. That is,
The shock absorber 1 is formed of an inner cylinder 12a and an outer cylinder 12b doubly. 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 two cylinders 12a and 12b. The interior of the inner cylinder 12a is formed in the upper chamber A by a piston 17 fixed to the upper end of the piston rod 11.
And a lower chamber B. The lower chamber B and the outer liquid chamber C are communicated 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.
Note that the step motor 3
Is housed.

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

Next, the structure of the valve body 13 will be described with reference to FIG. 4, which is an enlarged view of a main part of FIG. That is, the valve body 13 is connected to the first
An intermediate chamber E is formed between the valve body 31 and the second valve body 32. 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. The first communication hole 31a is closed to extend the damping valve 3 on the upper surface.
3, and a check valve 34 is provided on the lower surface to close the second communication hole 31b. The second valve body 32 includes a first communication hole 32a that connects the intermediate chamber E and the upper chamber A, a second communication hole 32b that communicates the reservoir chamber D with the upper chamber A, and an outer side of the intermediate chamber E. A third communication hole 32c that communicates with the liquid chamber C is formed, and a pressure-side damping valve 35 is provided on the upper surface to cover the first communication hole 32a.
A check valve 36 is provided on the lower surface to cover 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 each port 37a, 37b,
The first communication hole 31a and the reservoir chamber D can be communicated with each other by bypassing the expansion-side damping valve 33 by the spaces 37c, 37d, and 37e and the inner circumference. The bypass passage F is formed so that the one communication hole 32a can communicate with the reservoir chamber D or the intermediate chamber E.

The communication groove 3 is provided in the support cylinder 37.
An adjuster 38 having a portion 8a for changing the cross-sectional area of the bypass passage F is rotatably mounted. In addition, this adjuster 3
Numeral 8 is connected to the step motor 3 and is rotated by the drive of the step motor 3.

Therefore, when the pressure side stroke is performed, the fluid in the upper chamber A opens the pressure side damping valve 35 to reach the intermediate chamber E and the bypass chamber F to the reservoir chamber D or the intermediate chamber. The flow path to E can be circulated, and the damping coefficient can be changed in five steps according to the turning position of the adjuster 38, as shown in the damping force characteristic diagram of FIG. The number shown at the end of the characteristic line is the step motor 3
The stepping motor 3 has a driving step of 1
Drive every 0 steps.

On the other hand, when the expansion stroke is performed, the fluid in the lower chamber B and the fluid in the outer liquid chamber C communicated with the lower chamber B flows into the intermediate chamber E through the third communication hole 32c, and then flows into the expansion chamber damping valve 3.
3, 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 can be circulated. In this case as well, as shown in FIG. Thus, the attenuation coefficient can be changed in five stages.
In addition, as shown in the damping force characteristic diagram of FIG. 5 and the damping coefficient characteristic diagram of FIG. 6, the portion of the bypass path F bypassing the expansion-side damping valve 33 is maximally opened to control the expansion side to the minimum damping coefficient. In the case of (40 steps), the part bypassing the compression side damping valve 35 is closed and the compression side is controlled to the maximum damping coefficient, and conversely, the part bypassing the extension side damping valve 33 as 0 step. Is closed and the extension side is controlled 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. In the case of 20 steps, the bypass path F
The opening degree of the part bypassing the expansion-side damping valve 33 and the opening degree of the part bypassing the compression-side attenuation valve 35 are all medium, and the expansion coefficients on both sides of the expansion similarly have a moderate attenuation coefficient.

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

Next, the configuration of the controller 2 for controlling the driving of the step motor 3 will be described. The controller 2 includes, as shown in FIG.
/ D conversion circuit 2b, CPU 2c, and memory 2d. Roll control, scut control, dive control, pitching are performed based on the input signals from the sensors 5a to 5f so that the shock absorber 1 is used as an optimal damping coefficient to obtain optimal ride comfort, steering stability, and vehicle attitude. Control such as control and bounce control is performed. Here, roll control will be described.

FIG. 7 shows a control flow in the case of roll control. When roll control is performed, input signals from the steering sensor 5a, the vehicle speed sensor 5b, and the load sensor 5f are used. This roll control is started when the steering angle θ obtained from the steering sensor 5a exceeds a predetermined threshold value θA, as shown in the time chart of FIG. That is, when it is determined from the straight traveling state shown in step 101 that the steering angle θ has exceeded the predetermined threshold value θA as shown in step 102, the flow proceeds to step 103 to start the roll control. Each of the sensors 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. The control constant δ (x) corresponds to the number of drive steps of the step motor 3 as shown in FIG.

Step 105 is a step in which the front wheels are turned and the outer wheels are turned.
The rear wheel is turned against the inner shock absorber 1
Δt more time than the shock absorber of the turning outer wheel of
(See FIG. 10) to perform a process of giving a control phase difference τ.

Step 106 is a step of outputting a drive control signal to the step motor 3. As shown in the operation explanatory diagram of FIG. 9, the shock absorber 1 L on the turning outer wheel side (subsided side) has a high attenuation on the pressure side. The shock absorber 1R on the turning inner wheel side (lifting side) outputs a control signal with a low damping coefficient on the compression side and a high damping coefficient on the expansion side. still,
When the vehicle is traveling straight without detecting a roll, both sides are controlled to have 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 opposite direction, and the steering angle θ exceeds the threshold value θA. It is a step of determining whether or not
If YES, the flow returns to step 103 to continue the roll control, and if NO, the flow returns to the straight running control (step 101). Incidentally, 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, during straight running, the damping coefficient of each shock absorber 1 is controlled to a medium damping coefficient on both the extension and pressure sides, and a running characteristic with a high contact feeling, excellent maneuverability, and high sports properties can be obtained.

Next, the steering is performed, and the steering angle θ
Exceeds a predetermined threshold value θA, 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 the control constant δ (x), As shown in FIG. 9, the step motor 3 of the shock absorber 1 is driven by a predetermined number of steps to control the shock absorber 1R on the turning outer wheel to the compression side high damping coefficient, the extension side low damping coefficient, and the turning inner wheel side. Is controlled to the extension-side high damping coefficient and the compression-side low damping coefficient.

[0031] Then, as shown this time, in FIG. 10 is a time chart showing a step change of the stepping motor 3 corresponding to the damping coefficient changes during left turning in the real施例,
As a result of giving the control phase difference τ to the front wheels ( see step 105 in the flowchart of FIG. 7), the right side of the front wheels (outside turning )
The left side of the rear wheel and shock absorber (RH) of the wheel) (handed times
Of the damping force of the shock absorber (LH)
Rise is delayed. As a result, the turning outer wheel side of the front wheel
Sinking suppression action and lifting suppression on the inner side of turning rear wheel
Production delays compared to others, front wheel turning outer wheel side sinks down
While the inner side of the turning inner wheel of the rear wheel rises first.
The ideal diagonal roll that rolls diagonally
It becomes .

Accordingly, by setting the pressure stroke side of the shock absorber 1 on the turning outer wheel to a high damping coefficient, the sinking of the vehicle body on the turning outer wheel is suppressed, while the shock absorber 1 on the turning inner wheel is suppressed. The turning stroke side of the
By suppressing the lifting of the vehicle body wheel side, it is possible to suppress the roll of the vehicle body. At the same time, that the delayed front turning outer wheel and the rise of the damping force of the turning inner rear wheel as shown in FIG. 10, without the parallel roll roll angle is the same before and after the vehicle body, the roll diagonally To become a diagonal roll, the roll angle is suppressed,
High steering stability is obtained.

In addition, when the shock absorber 1 is operated in both directions of expansion and compression when the wheels pass through unevenness such as undulations of the road surface during such a turn, the side having a high damping coefficient for performing roll suppression is used. Since the transmission coefficient is controlled to be low on the opposite stroke side, the transmission rate is reduced, and the transmission of the road surface input to the vehicle body is suppressed by that much. Thus, along with the ride comfort of the deterioration is suppressed, the disturbance of the vehicle attitude due to the road surface input is Ru is suppressed.

[0034] the following, explanation to have been While specific configurations for Example not limited to this embodiment, for example, in the embodiment, let me delay the shock absorbers of the front wheels of the turning outer wheel side for a predetermined time As a roll control means for increasing the damping force, a controller that performs calculation and processing is shown,
Although the control phase difference is given in the processing inside the controller, the roll control means includes, for example, a 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). The transmission speed during the transmission may be changed to delay the time until the target high damping coefficient is obtained.

In addition, when the vehicle travels straight, both the extension and the compression are controlled to have a medium damping coefficient. However, a low damping coefficient may be used to improve the riding comfort. In this case, the coordinator
In the bypass path, a configuration in which both of the portions bypassing both the extension side and the compression side damping valves are fully opened can be formed.

[0036]

As described above, in the vehicle suspension system according to the present invention, when detecting the roll, the damping coefficient on the compression side of the shock absorber of the turning outer wheel is increased while the roll is detected.
Increase the damping coefficient of the extension side for the shock absorber of the turning inner wheel, further, when increasing the damping coefficient of the sheet Yokkuabusoba, front and rear wheel of turning inner turning wheel
Since the shock absorber and a rear wheel unit provided with a roll control means for roll control for increasing the delayed allowed by the attenuation coefficient predetermined time for the shock absorber after the turning outer of, at the time of the roll, sinking swivel outer side In addition to suppressing the rise of the inner wheel side of the turning, the body roll is prevented, and the outer turning wheel of the front wheel sinks down the most.
On the other hand, a diagonal roll in which the turning inner wheel of the rear wheel rises first and rolls diagonally is obtained, and good roll characteristics are obtained. Thus, the pureness of the suspension in a state where the vehicle suspension is not controlled is obtained. The tuning itself does not need to be a tuning that causes a diagonal roll. It is possible to obtain good characteristics such that deterioration of riding comfort when driving straight ahead and a decrease in steering stability do not appear while rolling so that a diagonal roll occurs. It has the effect of being able to. Further, in the present invention, at the time of the roll control, the extension side of the shock absorber of the turning outer wheel, which is on the stroke side opposite to the side on which the high damping coefficient is controlled in order to suppress the roll, and the shock of the turning inner wheel. Since the pressure side of the absorber has a low damping coefficient, during roll control, if it passes over unevenness on the road surface, road surface input in the stroke direction is absorbed without being transmitted to the vehicle body, and the ride comfort due to this road surface input is deteriorated. , as well as that Sosu the effect that the disturbance of the vehicle attitude is suppressed.

[Brief description of the drawings]

1 is an overall view showing a vehicle suspension system of the present onset AkiraMinoru施例.

2 is a sectional view showing the upper half of the shock absorber of the real施例device.

3 is a cross-sectional view showing the lower half of the shock absorber of the real施例device.

4 is an enlarged cross-sectional view showing the main portion of the shock absorber of the real施例device.

5 is a damping force characteristic diagram corresponding to the shock absorber piston velocity of the actual施例device.

6 is a damping coefficient characteristic graph corresponding to a step position of the step motor of the shock absorber of the real施例device.

7 is a flowchart showing the control flow of the controller in real施例device.

[8] the steering angle θ in a real施例device, the damping force DF, is a time chart illustrating the steps of a relationship between the step motors.

9 is an explanatory diagram of the operation of the real施例device when the vehicle body rolls occurs.

10 is a time chart showing a step change of the step motor corresponding to the damping force coefficient changes during left turning in a real施例device.

[Explanation of symbols]

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

Continuation of the front page (56) References JP-A-61-75007 (JP, A) JP-A-63-145113 (JP, A) JP-A-63-145114 (JP, A) Jpn. , U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60G 17/015

Claims (1)

(57) [Claims] 1. A damping coefficient which is provided between a wheel and a vehicle body of a vehicle and changes a compression side to a low attenuation when the expansion side is set to a high attenuation, and changes a compression side to a low attenuation when the compression side is set to a high attenuation. A shock absorber formed so as to be possible, a roll detecting means for detecting that the vehicle is in a roll state, and a roll-detecting shock absorber for a turning outer wheel, while increasing a compression-side damping coefficient while detecting a roll. Increase the damping coefficient on the extension side,
In order to increase the compression coefficient or the extension coefficient,
The front wheel of the turning outer wheel and the rear wheel of the turning inner wheel
Delay the rear wheel by a predetermined time to increase the damping coefficient
And a roll control means for performing roll control .