JPH0769025A - Damping coefficient control device for shock absorber - Google Patents

Abstract

PURPOSE:To damp vibration of a car body properly and effectively without causing excess and deficiency of damping force even if apparent sprung mass is changed according to travel of a vehicle. CONSTITUTION:Sprung vertical directional speed Zd and vertical directional relative speed Yd between sprung and unspring are detected respectively by a sprung speed detecting device M1 and a relative speed detecting device M2, and actual support loads P of respective wheels when a vehicle travels are detected or estimated by a load detecting device M3, and a damping coefficient C of a shock absorber S is controlled according to Zd/Yd by a control device M4, and the damping coefficient is corrected so as to be increased and decreased according to the magnitude of the support loads P of the respective wheels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber incorporated in a suspension of a vehicle such as an automobile, and more particularly, to a damping coefficient control device for a shock absorber.

[0002]

2. Description of the Related Art As one of damping control devices for a shock absorber in a vehicle such as an automobile, for example, Japanese Patent Application Laid-Open No. 3-27680 filed by the same applicant as the applicant of the present application.
As described in the section of the prior art of No. 8, the vertical velocity on the spring is Z based on the skyhook damper theory.
Let d be the relative velocity in the vertical direction between the sprung and unsprung portions, and let the damping force of the shock absorber be Zd / Yd.
Damping coefficient control devices that are configured to control in accordance with the above are well known in the art.

According to such a damping coefficient control device, since the damping force of the shock absorber is controlled on the basis of the skyhook principle, the damping force of the shock absorber is controlled according to the speed with respect to the absolute space on the spring. The upper vibration can be effectively damped.

[0004]

However, in the conventional damping coefficient control device based on the skyhook damper theory as described above, since the skyhook damping coefficient is given as a constant, the vehicle travels on a hill or when the vehicle travels on a slope. When the load moves due to turning or acceleration / deceleration, and the apparent mass on the spring changes as a result, there is a problem that the damping force becomes excessive or insufficient. For example, if the skyhook damping coefficient is set based on the sprung mass when the vehicle is stationary, the apparent sprung mass of the front wheels when the vehicle climbs up is reduced, and the damping force is too high. On the contrary, the damping force becomes too low for the rear wheels due to the increase of the apparent mass on the spring, so that the vibration of the vehicle body cannot be properly damped for both the front and rear wheels.

In view of the above-mentioned problems in the conventional damping coefficient control device based on the skyhook damper theory, the present invention changes the apparent mass on the spring due to the load movement accompanying the traveling of the vehicle. Also, the damping coefficient control device improved so that the damping force can be properly controlled without excess or deficiency, and thereby the vibration of the vehicle body can be appropriately and effectively damped as compared with the conventional damping coefficient control device. Is intended to provide.

[0006]

According to the present invention, there are provided the following objects. (1) A damping member disposed between an unsprung part and an unsprung part, as shown in FIG. 1 (A). A sprung speed detecting means M for detecting a vertical speed Zd on the spring by using a damping coefficient control device for a shock absorber S having a variable coefficient.
1, a relative speed detecting means M2 for detecting a relative speed Yd in the vertical direction between the sprung and unsprung portions, and a load detecting means M for detecting a supporting load P of the unsprung portion while the vehicle is traveling.
3 and the damping coefficient of the shock absorber is Zd / Yd
A shock absorber damping coefficient control device configured to increase / decrease the damping coefficient in accordance with an increase / decrease in the supporting load P as the vehicle travels. Alternatively, as shown in FIG. 1 (B), (2) a damping coefficient control device for a shock absorber S having a variable damping coefficient disposed between the sprung portion and the unsprung portion is provided, so that the vertical direction on the spring is increased. Speed detection means M1 for detecting the speed Zd of the vehicle, relative speed detection means M2 for detecting the relative speed Yd in the vertical direction between the sprung and unsprung parts, and the inclination angle θ of the traveling road surface. Inclination angle detection means M5 and the unsprung support load P according to the inclination angle θ
And a control means M for controlling the damping coefficient of the shock absorber according to Zd / Yd.
4 and the control means is configured to increase / decrease the damping coefficient according to the increase / decrease of the supporting load P, or a damping coefficient control device for a shock absorber, or as shown in FIG. 1 (C). (3) A sprung speed detecting means M1 for detecting a vertical speed Zd on the spring by using a damping coefficient control device for a shock absorber S having a variable damping coefficient arranged between the sprung portion and the unsprung portion. A relative speed detecting means M2 for detecting a vertical relative speed Yd between the sprung portion and the unsprung portion, an acceleration detecting means M7 for detecting a horizontal acceleration G on the spring, and the acceleration G. Load calculation means M8 for calculating the unsprung support load P according to
And a control means M4 for controlling the damping coefficient of the shock absorber according to Zd / Yd, the control means of the shock absorber configured to increase / decrease the damping coefficient in response to an increase / decrease in the support load P. This is achieved by the damping coefficient controller.

[0007]

9 and 10 are explanatory views showing a single wheel model of an actual vehicle and a single wheel model of a vehicle based on the skyhook damper theory, respectively. In these figures, 100 and 110 respectively indicate sprung mass and unsprung mass of mass M,
Reference numerals 120 and 130 respectively denote a shock absorber having a damping coefficient C and a suspension spring having a spring constant K, and 140 denotes an absolute space. Further, in these figures, X represents the vertical displacement of the unsprung portion, Y represents the relative displacement between the sprung and unsprung portions, and Z represents the vertical displacement of the sprung portion.

Now, assume that the vertical velocities of the sprung and unsprung are Xd and Zd, respectively, and the vertical acceleration of the sprung is Zd.
Assuming that td is the relative velocity between the sprung and unsprung portions, and Yd is the equation of motion in the single-wheel model of the actual vehicle shown in FIG. .

## EQU1 ## MZtd = -C (Zd-Xd) -K (Z-X) =-CYd-KY

The equation of motion in the single wheel model of the vehicle based on the skyhook damper theory shown in FIG. 10 is C *.
Is expressed as the skyhook damping coefficient by the following equation 2,
The transfer function from the unsprung displacement X to the unsprung displacement Z is expressed by the following equation 3.

[0010]

## EQU2 ## MZtd = -C * Zd-K (Z-X) =-C * Zd-KY

[Formula 3] Z / X = K / (Ms ² + C * s + K)

Since the transfer function of equation 3 is a second-order lag system,
If the damping ratio ζ expressed by the following equation 4 is less than 2 ^-1/2 , there is no resonance peak at any frequency, and the damping ratio ζ is far more than 2 ^-1/2. If it is high, resonance will not occur, but the actual damping force will increase more frequently, which may deteriorate the riding comfort of the vehicle. Therefore, the skyhook damping coefficient C * is such that the damping ratio ζ becomes about 2 ^-1/2 . It is known that it is preferable to set such that

[Formula 4] ζ = C * / 2 (MK) ^−1/2

However, as can be seen from the equation (4), even if the skyhook damping coefficient C * is set so that the damping ratio ζ becomes about 2 ^-1/2 , the apparent sprung mass is generated due to the load movement accompanying the running of the vehicle. If the mass M of the vehicle changes, the damping ratio ζ also changes to a value other than the preferable value, and it becomes impossible to appropriately damp the vibration of the vehicle body.

According to the structure of the present invention, the vertical velocity on the spring is Zd, and the vertical relative velocity between the sprung and unsprung is Yd, and the damping coefficient of the shock absorber is Z.
Not only is it controlled according to d / Yd, but the damping coefficient is also corrected according to the increase / decrease of the actual supporting load P under the spring while the vehicle is running. Even if the apparent mass M on the spring changes due to this, the damping ratio ζ is maintained at a constant value of, for example, its preferable value of about 2 ^−1/2 , and therefore the damping ratio ζ of the vehicle is reduced. Vibrations of the vehicle body are appropriately and effectively damped without any deterioration in riding comfort and lack of damping.

[0014]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic configuration diagram showing a first embodiment of a damping coefficient control device for a shock absorber. In FIG. 2, fr, fl, rr, and rl indicate members corresponding to the right front wheel, left front wheel, right rear wheel, and left rear wheel, respectively.

In FIG. 2, reference numeral 10 denotes a damping force variable type shock absorber known per se. Although not shown in FIG. 2, the upper end portion of the piston rod 12 serves as a sprung body. The lower end of the main body 14 is connected to a suspension member as an unsprung member. The shock absorber 10 is an actuator 1 fixed to the vehicle body.
6, the damping coefficient can be switched to the highest value (hard), the lowest value (soft) and a value between them in n steps. Each shock absorber 10 has an air chamber 1
8 is integrally provided with a load sensor 22 for detecting the supporting load Pi of the corresponding wheel at a position close to each air spring.

Each actuator 16 has a vertical velocity Zd on the spring detected by the sprung velocity detecting means 24.
, The relative speed Yd in the vertical direction between the sprung and unsprung parts detected by the relative speed detecting means 26, the load detecting means 2
The electronic control unit 28 is controlled on the basis of the supporting load Pwi of the corresponding wheel detected by 7.

FIG. 3 is a block diagram showing a concrete example of the electronic control unit 28 shown in FIG. In addition, in FIG.
The parts corresponding to the parts shown in are given the same reference numerals as those given in FIG. Further, in FIG. 3, the symbol i (= 1) indicating that the symbols and signals of the respective members correspond to the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel, respectively.
~ 4) are attached.

The electronic controller 28 includes a microcomputer 30 as shown in FIG. Microcomputer 30 may be of a general configuration as shown in FIG. 3, and central processing unit (CPU) 32.
, Read only memory (ROM) 34, random access memory (RAM) 36, and input port device 38
And an output port device 40, which are connected to each other by a bidirectional common bus 42.

In the input port device 38, a signal indicating the vertical acceleration Ztdi on each spring detected by the vertical acceleration sensor 44i provided corresponding to each wheel is integrator 46i.
A signal indicating the vertical velocity Zdi on each spring, which is first-order-integrated by and the high-frequency component is removed by the low-pass filter 48i, and the corresponding spring and spring detected by the stroke sensor 50i provided corresponding to each wheel. The signal indicating the relative displacement Yi between
A signal indicating the vertical relative velocity Ydi between each sprung and unsprung part calculated by differentiating the order, the supporting load of each wheel detected by the load sensor 22i and having the high-frequency component removed by the low-pass filter 54i. A signal indicating Pwi is input.

Thus, the vertical acceleration sensor 44i and the integrator 46i cooperate with each other to form the sprung speed detecting means 2 shown in FIG.
4 corresponds to the sprung speed detecting means 24i, and the stroke sensor 50i and the differentiator 52i cooperate with each other to form the relative speed detecting means 26i corresponding to the relative speed detecting means 26 of FIG. , The load sensor 22i and the low-pass filter 54i cooperate with each other to form a load detecting means 27i corresponding to the load detecting means 27 of FIG.

The input port device 38 appropriately processes the signal input thereto, and in accordance with the instruction of the CPU 32 based on the program stored in the ROM 34, the CPU and the RAM.
The processed signal is output to 36. R
The OM 34 stores a control program based on the flowchart shown in FIG. 4 and a map corresponding to the graphs shown in FIGS. 5 to 8. The CPU 32 is adapted to perform various calculations and signal processing as will be described later based on the flowchart shown in FIG. Output port device 40 is CP
According to the instruction of U32, a control signal is output to the actuator 16i of the shock absorber provided corresponding to each wheel via the drive circuit 56i.

Next, the operation of the illustrated first embodiment will be described with reference to the flow chart shown in FIG. The control by the electronic control unit 28 is started by closing an ignition switch (not shown), and is ended after a while after the ignition switch is opened.

First, in step 10, RAM3
6 and the like are initialized and i is set to 1, and in step 20, a signal indicating the supporting load Pi of each wheel detected by the load sensor 22i is read. In step 30, the signal indicating the supporting load Pi is subjected to high-frequency component removal by the low-pass filter 54i to calculate the supporting load Pwi of each wheel after the low-pass filter processing, and in step 40, it is shown in FIG. Based on the support load Pwi, the base damping coefficient Cbi (Cbi1 to Cbin) of each shock absorber is calculated according to the map corresponding to the graph.

In step 50, the gain Kwi is calculated based on the map corresponding to the graph shown in FIG. 6, and in step 60, the vertical velocity Zdi on each spring and each sprung and unsprung mass. A signal indicating the relative speed Ydi in the up-and-down direction between the two is read, and in step 70, the relative speed Ydi is set in order to avoid that the denominator of the calculation in step 80 described later becomes 0. It is corrected according to the map corresponding to the graph shown in FIG.

In step 80, the damping coefficient Csi of each shock absorber based on the skyhook theory corrected according to the supporting load Pwi is calculated according to the following equation 5,
At step 90, it is judged if the absolute value of the sprung speed Zdi is less than or equal to the reference value Zdo, and | Zdi |> Zdo.
If it is determined that the damping coefficient C i is at 100, the damping coefficient C i is based on the skyhook theory.
If si is set and it is determined that | Zdi | ≦ Zdo, the damping coefficient Ci is set to the base damping coefficient Cbi in step 110.

[Equation 5] Csi = KwiZdi / Ydi (i = 1, 2, 3, 4)

In step 120, the control current Ii supplied to each actuator 16i is calculated according to the damping coefficient Ci based on the map corresponding to the graph shown in FIG. 8, and in step 130 each shock is calculated. By outputting the control current Ii to the actuator of the absorber, the damping coefficient of each shock absorber is controlled to a value corresponding to Ci.

In step 140, i is incremented by 1, in step 150 it is judged whether i is 5, and when it is judged that i is not 5, step 20 is executed. Returning to step 20, when it is determined that i = 5, i is reset to 1 in step 160 and then the process returns to step 20.

Thus, according to the first embodiment, the signal indicative of the supporting load Pi of each wheel detected by the load sensor 22i is read in step 20, and the signal indicative of the supporting load Pi is read in step 30. The high-frequency component is removed by the low-pass filter 54i to calculate the support load Pwi of each wheel after the low-pass filter processing, and in step 40, each support load Pwi is calculated based on the support load Pwi according to the map corresponding to the graph shown in FIG. The base damping coefficient Cbi of the shock absorber is calculated. In step 50, the gain K is calculated based on the map corresponding to the graph shown in FIG.
wi is calculated, and in step 60, a signal indicating the vertical velocity Zdi on each spring and the vertical relative velocity Ydi between each sprung and unsprung is read.
In step 80, the relative velocity Ydi is corrected according to the map corresponding to the graph shown in FIG. 7, and in step 80, the damping coefficient of each shock absorber based on the skyhook theory is corrected according to the supporting load Pwi according to the equation (5). Csi is calculated.

Then, in step 90, the sprung speed Zi
If the absolute value of the sprung speed is larger than the reference value, the damping coefficient Ci is set to the damping coefficient Csi based on the skyhook theory in step 100, and the absolute value of the sprung speed is If it is less than the reference value, the damping coefficient Ci is set to the base damping coefficient Cbi in step 110.

Therefore, the damping coefficient C of each shock absorber
When i is set based on the skyhook theory, not only is it controlled according to the speed ratio Zdi / Ydi, but it is also increased or decreased according to the actual supporting load Pwi of each wheel, so each shock absorber is It functions as a skyhook damper having an optimum damping coefficient according to the actual supporting load of each wheel that fluctuates as the vehicle travels, and thereby vibration on the spring can be appropriately and effectively damped.

FIG. 9 is a schematic block diagram showing a second embodiment of the damping coefficient control device for the shock absorber, and FIG. 10 is a block diagram showing a concrete example of the electronic control device 28 shown in FIG. . In addition, in FIG. 9 and FIG.
Also, the parts corresponding to the parts shown in FIG. 3 are denoted by the same reference numerals as those given in these figures.

In this embodiment, the signal indicating the supporting load Pi of each wheel detected by each load sensor 22 is input to the input port device 38 of the electronic control unit 28 without being low-pass filtered. Has become. Further, the input port device 38 has a signal indicating the vehicle speed V detected by the vehicle speed sensor 60, a signal indicating the lateral acceleration Gy of the vehicle body detected by the lateral acceleration sensor 62, and the front and rear of the vehicle on the road surface detected by the inclination angle sensor 64. A signal indicating the inclination angle φ of the direction and a signal indicating whether or not the door is opened are input by a door switch 66i provided on each door.

As is well known, during acceleration / deceleration traveling, turning, or traveling on a slope, load movement occurs between the front and rear wheels or between the left and right wheels, and the supporting load of each wheel fluctuates. The longitudinal acceleration of the vehicle body Gx (the front of the vehicle is positive), the lateral acceleration Gy (the right of the vehicle is positive), the slope angle φ of the slope (the positive for uphill), and the sprung mass of the vehicle Assuming M, the load movement amount in each case is the sprung mass M and the longitudinal acceleration G, respectively.
It is proportional to the product of x, the mass of the sprung mass M and the lateral acceleration Gy, and the product of the sprung mass M and the sine of the tilt angle φ.

For example, when the coefficient of load movement during acceleration / deceleration of the vehicle is Kxi, which is determined by the wheel base and the height of the center of gravity, Kxi.M.Gx (Kx1 <0, Xx2 <0, Xx3>
0, Kx4> 0). When the coefficient of load movement during turning of the vehicle is Kyi, which is determined by the tread and the height of the center of gravity, Kyi · M · Gy (Ky1 <0, Ky2> 0, Ky3 <
0, Ky4> 0). Also, when the vehicle travels on a slope, the load moving amount is Ksi, G, sinφ (Ks1 <0, K, where Ksi is a coefficient determined by the wheel base and the height of the center of gravity.
s2 <0, Ks3> 0, Ks4> 0).

Therefore, in the second embodiment, as will be described later in detail, the supporting load Pi of each wheel in the stopped state of the vehicle is detected by the load sensor 22, and the detection result of the vehicle speed sensor 60 or the like is obtained. Based on this, the load movement amount associated with the traveling of the vehicle is calculated, whereby the support load Pwi of each wheel during the traveling of the vehicle is calculated as the sum of the support load Pi and the load movement amount.

Next, the operation of the illustrated second embodiment will be described with reference to the flow chart shown in FIG. In this embodiment as well, the control by the electronic control unit 28 is started by closing an ignition switch, which is not shown in the figure, and is ended after a while after the ignition switch is opened. Further, in FIG. 11, the flag F relates to whether or not the supporting load Pi (i = 1 to 4) of each wheel in the stopped state of the vehicle should be updated, and 1 is the supporting load Pi. Indicates that it is in a situation to be updated.

In step 20, the supporting load Pi of each wheel detected by the load sensor 22i is read and the flag F is reset to zero. In step 22, the vehicle speed V detected by the vehicle speed sensor 60 is read, and in step 24, the longitudinal acceleration Gx of the vehicle body is calculated as the time differential value of the vehicle speed V. In step 26, the lateral acceleration Gy of the vehicle body detected by the lateral acceleration sensor 62 and the inclination angle φ of the road surface detected by the inclination angle sensor 64 are read, and in step 30, the vehicle is stopped. Let Pt be the total of the supporting loads Pi of the four wheels at
With the gravitational acceleration as g, the supporting load Pwi of each wheel is calculated according to the following equation 6.

[Equation 6] Pwi = Pi + Pt / g (Kxi · Gx + Kyi · Gy + Ksi · sinφ)

In step 170, it is determined whether the vehicle speed V is 0. If it is determined that the vehicle speed V is not 0, the process returns to step 22. Step 1
At 80, the door switch signal is read and it is determined whether or not any door is opened. When it is determined that the vehicle speed V is 0 and any of the doors is opened, the flag F is set to 1 in step 190, and it is determined that neither of the doors is opened. When is performed, it is determined in step 200 whether the flag F is 1 or not. Flag F is 1
If it is determined that the flag F is not 1, the process returns to step 20, and if it is determined that the flag F is not 1, the process returns to step 22.

Thus, according to the second embodiment, the supporting load Pi of each wheel in the stopped state of the vehicle detected by the load sensor 22i in step 20 is read, and the vehicle speed sensor 60 in step 22 is read. Vehicle speed V detected by
Is read, the longitudinal acceleration Gx of the vehicle body is calculated as the time differential value of the vehicle speed V in step 24, and the lateral acceleration Gy of the vehicle body detected by the lateral acceleration sensor 62 and the inclination angle sensor 64 are detected in step 26. The obtained road inclination angle φ is read, and in step 30, the supporting load Pwi of each wheel is calculated in accordance with the equation 6, and in step 40, FIG.
Support load P according to the map corresponding to the graph shown in
The base damping coefficient Cbi of each shock absorber is calculated based on wi.

In this embodiment, if there is a possibility that the sprung mass changes due to getting on and off of the occupant of the vehicle and unloading of the loaded luggage, the steps 170 to 200 and step 20 are executed. The support load Pi of each wheel when the vehicle is stopped is reliably updated.

Also, as in the case of the first embodiment, step 5
In 0 to 80, the damping coefficient Csi of each shock absorber based on the skyhook theory corrected according to the supporting load Pwi according to the equation 5 is calculated, and in step 90, the magnitude of the absolute value of the sprung speed is determined. When the absolute value of the sprung speed is larger than the reference value, the damping coefficient Ci is set to the damping coefficient Csi based on the skyhook theory in step 100. When the absolute value of the sprung speed is less than the reference value, the step 110 is executed. Where the damping coefficient Ci is the base damping coefficient Cbi
Is set to.

Therefore, also in this embodiment, the damping coefficient Ci of each shock absorber is not only controlled according to the speed ratio Zdi / Ydi when it is set based on the skyhook theory, but also the actual value of each wheel. Each shock absorber acts as a skyhook damper having an optimum damping coefficient according to the actual supporting load of each wheel that fluctuates as the vehicle travels, thereby increasing the sprung mass. Vibrations can be appropriately and effectively damped.

The damping coefficient Ci of each shock absorber
Is controlled to a damping coefficient Csi based on the skyhook theory, for example, in a situation where the vehicle travels on a good road and the absolute value of the sprung speed Zdi is very small, the damping coefficient becomes a very small value. Since the setting is made, when the unsprung part receives a disturbance input from the road surface in such a situation, the actual increase of the damping coefficient is delayed due to the delay of the control, so that the vibration on the sprung is likely to occur.

On the other hand, in any of the illustrated embodiments,
The base damping coefficient Cbi of each shock absorber is calculated according to the actual support load Pwi of each wheel, and when the absolute value of the sprung speed Zdi is larger than the reference value Zdo, step 10 is executed.
At 0, the damping coefficient Ci is set to the damping coefficient Csi based on the skyhook theory, but when the absolute value of the sprung speed is less than the reference value, at step 110 the damping coefficient Ci is set to the base damping coefficient Cbi. When a damping coefficient C i is controlled to a damping coefficient Csi based on the skyhook theory regardless of the absolute value of the sprung speed, a certain damping coefficient is always ensured according to the actual supporting load of each wheel. Compared with the above, it is possible to reduce the vibration on the spring due to the delay of the control, and it is possible to reduce the number of switching steps and the switching frequency of the damping coefficient of each shock absorber.

In each of the illustrated embodiments, the damping coefficient Ci of the shock absorber is controlled to increase / decrease stepwise in n steps, but the damping coefficient of the shock absorber is continuously controlled to increase / decrease. May be.

Although the present invention has been described in detail above with reference to specific embodiments, the present invention is not limited to the above-mentioned embodiments, and various other embodiments are also possible within the scope of the present invention. It will be apparent to those skilled in the art that

For example, when the suspension has a gas spring as in the illustrated embodiment, the support load Pi of each wheel detects the pressure in the gas spring by a pressure sensor, and each pressure is set to the pressure receiving area of the corresponding gas spring. It may be obtained by dividing by.

Further, particularly in the second embodiment, since the load movement amount in the lateral direction of the vehicle is calculated based on the lateral acceleration Gy of the vehicle body, the load movement amount due to the turning of the vehicle and Both the load movement amount due to the inclination of the road surface in the lateral direction of the vehicle can be calculated at the same time, but the load movement amount in the lateral direction of the vehicle is estimated from the vehicle speed V and the steering angle θ as the load movement amount due to the turning of the vehicle. The load movement amount resulting from the inclination of the road surface may be calculated based on the inclination angle of the road surface in the lateral direction of the vehicle detected by the inclination angle sensor, and may be calculated as the sum thereof.

In the second embodiment, the load movement amount in the vehicle front-rear direction is calculated based on the differential value of the vehicle speed V. The load movement amount caused by the acceleration / deceleration of the vehicle and the inclination of the road surface in the vehicle front-rear direction. Is calculated as the sum of the amount of load movement due to the vehicle load, but the amount of load movement in the vehicle front-rear direction is based on the longitudinal acceleration Gx of the vehicle body and the amount of load movement caused by acceleration / deceleration of the vehicle and the vehicle front-back direction It may be calculated as the sum of the load movement amount caused by the inclination of the direction.

[0051]

As is apparent from the above description, according to the present invention, the vertical velocity on the spring is Zd, and the relative vertical velocity between the sprung and unsprung is Yd. The damping coefficient is not only controlled according to Zd / Yd, but is also corrected according to the increase / decrease of the actual supporting load P under the spring while the vehicle is running. Even if the apparent mass M on the spring changes due to the load movement, the damping ratio ζ can be maintained at a constant value of, for example, a preferable value of 2 ^−1/2 ,
Therefore, the vibration of the vehicle body can be appropriately and effectively damped without deteriorating the riding comfort of the vehicle and the lack of damping due to the excess or deficiency of the damping force.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a damping coefficient control device for a shock absorber according to the present invention, corresponding to the claims.

FIG. 2 is a schematic configuration diagram showing a first embodiment of a damping coefficient control device for a shock absorber according to the present invention.

FIG. 3 is a block diagram showing a specific example of the electronic control device shown in FIG.

FIG. 4 is a flowchart showing a control flow in the first embodiment shown in FIGS. 2 and 3.

FIG. 5 is a graph showing a relationship between a support load Pwi of each wheel and a base damping coefficient Cbi.

FIG. 6 is a graph showing a relationship between a support load Pwi of each wheel and a gain Kwi.

FIG. 7 is a vertical relative speed Y between the sprung and unsprung parts.
6 is a graph showing the relationship between the calculated value of di and the correction value.

FIG. 8 is a graph showing the relationship between the damping coefficient Ci and the control current Ii for the actuator.

FIG. 9 is a schematic configuration diagram showing a second embodiment of the damping coefficient control device for the shock absorber according to the present invention.

FIG. 10 is a block diagram showing a specific example of the electronic control device shown in FIG.

FIG. 11 is a flowchart showing a control flow in the second embodiment shown in FIGS. 9 and 10.

FIG. 12 is an explanatory diagram showing a model of an actual vehicle.

FIG. 13 is an explanatory diagram showing a vehicle model based on the skyhook damper theory.

[Explanation of symbols]

 10 ... Shock absorber 16 ... Actuator 20 ... Air spring 22 ... Load sensor 24 ... Spring speed detection means 26 ... Spring displacement detection means 27 ... Load detection means 28 ... Electronic control device 60 ... Vehicle speed sensor 62 ... Steering angle sensor 64 ... Longitudinal acceleration sensor 66 ... Inclination angle sensor 68 ... Door switch 100 ... Sprung 110 ... Unsprung 120 ... Shock absorber 130 ... Suspension spring 140 ... Absolute space

Claims (3)

[Claims] 1. A sprung velocity detecting means for detecting a vertical velocity Zd on the spring, which is a damping coefficient control device for a shock absorber having a variable damping coefficient arranged between an unsprung part and an unsprung part. A relative speed detecting means for detecting a relative speed Yd in the vertical direction between the sprung portion and the unsprung portion, a load detecting portion for detecting a supporting load P of the unsprung portion while the vehicle is traveling, and a shock absorber of the shock absorber. The damping coefficient is Zd / Y
and a control means for controlling according to d, the control means being configured to increase / decrease the damping coefficient according to the increase / decrease in the supporting load P accompanying the traveling of the vehicle. 2. A damping coefficient control device for a shock absorber having a variable damping coefficient arranged between an unsprung part and an unsprung part, and a sprung speed detecting means for detecting a vertical speed Zd on the spring. A relative speed detecting means for detecting a relative speed Yd in the vertical direction between the sprung portion and the unsprung portion, an inclination angle detecting means for detecting an inclination angle θ of a traveling road surface, and the inclination angle θ depending on the inclination angle θ. The load calculating means for calculating the support load P under the spring and the damping coefficient of the shock absorber are Zd.
/ Yd for controlling the damping coefficient of the shock absorber, wherein the controlling means is configured to increase / decrease the damping coefficient according to the increase / decrease of the supporting load P. 3. A sprung speed detecting means for detecting a vertical speed Zd on the spring by using a damping coefficient control device for a shock absorber having a variable damping coefficient arranged between an unsprung part and an unsprung part. A relative speed detecting means for detecting a relative speed Yd in the vertical direction between the sprung portion and the unsprung portion; an acceleration detecting means for detecting a horizontal acceleration G on the spring; It has a load calculation means for calculating the unsprung support load P and a control means for controlling the damping coefficient of the shock absorber according to Zd / Yd, and the control means responds to increase / decrease of the support load P. A shock absorber damping coefficient control device configured to increase or decrease the damping coefficient.