KR101629030B1 - Control method of continuously controllable damper - Google Patents

Abstract

The present invention relates to a control method of a continuous variable control damper, in which a reference damper current is calculated so as to correspond to a required damping force, a change allowable amount at which a damper current can be varied is calculated, In order to prevent the current from changing, a limited damper current is applied to the damper by applying the change allowable amount to prevent unnecessary current change. When the damper relative speed is high, the reference damper current is applied to the damper, So that the damping force can be obtained.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a continuous variable damper,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method of a continuously variable control damper, and more particularly, to a control method of a continuously variable control damper that prevents unnecessary control by limiting a current change applied to a continuously variable control damper according to a relative speed of a damper .

In recent years, a continuous variable control damper has been increasingly applied to improve driver's ride comfort and steering stability, mainly in luxury cars. The continuous variable control damper is a type in which a proportional control solenoid valve capable of controlling the degree of opening and closing of the passage is added according to the amount of current applied to a general hydraulic damper. Accordingly, when the relative motion between the vehicle body and the wheel, that is, the vibration, is generated, the oil passage flowing between the upper and lower chambers is interrupted around the piston connected to the damper rod to control the differential pressure applied to the piston, So that unnecessary vibration of the vehicle body can be reduced.

Here, a reference value for calculating the current to be applied to the proportional control solenoid valve of the continuous variable control damper is shown in Fig.

As shown in FIG. 1, the current to be applied to the damper is calculated by linear interpolation using the information on the required damping force Fs calculated from the relative speed Ds of the damper and the vertical velocity of the vehicle body. This current value is limited to the value between the maximum current (1300mA) corresponding to the softest state of the continuous variable control damper and the lowest current (300mA) corresponding to the hardest state.

As shown in FIG. 1, if the required damping force Fs calculated from the vertical velocity in the vertical direction of the vehicle body is referred to as Fa and the relative speed Ds of the continuous variable control damper measured at this time is a, 300mA), it is impossible to generate the damping force Fa required by the system, and the physically possible damping force becomes Fb which is much smaller than Fa, so that the effective control result can not be obtained.

That is, when the relative motion speed Ds of the damper is very small, it is not possible to obtain a large change in the damping force according to the current change. However, the case where the minimum current is calculated mathematically to obtain the value closest to the required damping force Fs Frequent occurrences usually appear as a sudden current change from the maximum current state to the lowest current value, which can lead to adverse effects on the system, leading to lower operating noise and mechanical durability of the valve.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a variable damping control apparatus capable of generating an effective damping force by limiting an allowable change amount of a current to be applied according to a relative speed of a continuously variable control damper, And to provide a control method capable of preventing the noise and mechanical endurance performance of the proportional control solenoid valve from being deteriorated due to abrupt current change under the absence of the current control.

In order to attain the above object, the present invention provides a control method for a continuously variable control damper, comprising: calculating a required damping force for controlling up-and-down vibration of a vehicle body through a vertical vibration speed of a vehicle body; Calculating a reference damper current from the damping force characteristic map of the continuously variable control damper by using the absolute value of the relative speed of the damper, calculating a changeable permissible amount from the current value applied to the current damper, Comparing a reference change amount that is a difference between a current applied to the current damper and the reference damper current with the change allowable amount and calculating a limited damper current that limits the reference damper current when the change allowable amount is small; Limiting damper current is supplied to the proportional control solenoid valve of the continuously variable control damper It may comprise the step of applying.

Determining whether the change allowable amount is a maximum change allowable amount which is a maximum value of the change allowable amount after the change allowable amount is calculated and comparing the reference change amount and the change allowable amount when the change allowable amount is less than the maximum change allowable amount .

And applying the reference damper current to the proportional control solenoid valve of the continuously variable control damper if the change allowable amount is equal to the maximum change allowable amount.

And applying the reference damper current to the proportional control solenoid valve of the continuously variable control damper when the change allowable amount is equal to or greater than the reference current change amount.

The control method of the continuous variable control damper according to the present invention limits the amount of current to be applied to the proportional control solenoid valve of the continuous variable control damper according to the relative speed of the continuous variable control damper to maintain the body vibration control performance, It is possible to prevent the noise of the proportional control solenoid valve or the mechanical endurance performance from deteriorating due to a sudden current change.

1 is a reference value for calculating a current to be applied to a proportional control solenoid valve of a general continuous variable control damper.
2 is a flowchart illustrating a method of controlling a continuously variable control damper according to an embodiment of the present invention.
3 is a reference value relating to the damper current in the control method of the continuously variable control damper of FIG.
Fig. 4 is a reference value relating to the change allowable amount in the control method of the continuously variable control damper of Fig.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention. Here, parts having similar configurations and operations throughout the specification are denoted by the same reference numerals.

Referring to FIG. 2, a flowchart illustrating a method of controlling a continuously variable control damper according to an embodiment of the present invention is shown.

As shown in Fig. 2, in the control method of the continuously variable control damper, a required damping force for controlling the up-and-down vibration of the vehicle body is calculated by using the vertical vibration velocity value of the vehicle body based on virtual fixed coordinates above the vehicle body (S1). The required damping force is calculated through Equation (1).

Where Fs is the required damping force, Cs is the control gain, and Zs is the up-and-down vibration displacement of the vehicle body. That is, the required damping force Fs can be calculated by multiplying the control gain Cs according to the running speed of the vehicle and the rate of change dZs / dt of the vertical vibration displacement with time of the vehicle body, that is, the vertical vibration speed. Here, the control gain Cs according to the running speed of the vehicle is a value stored separately in the controller, and is the same when the running speed of the vehicle is constant. Therefore, when the running speed of the vehicle is constant, the required damping force Fs changes in proportion to the vertical vibration speed of the vehicle body.

The reference damper current Cd applied to the damper is calculated S2 by applying a linear interpolation method using the relative damping force of the continuous variable control damper mounted to control the required damping force Fs and the vertical vibration of the vehicle body. The reference damper current is applied to the solenoid valve for controlling the degree of opening and closing of the oil passage in the continuously variable control damper in order to control the damping force of the continuously variable control damper. The reference damper current is calculated from FIG. 3, which is a characteristic map of the continuous variable control damper measured in advance according to the amount of current applied to the proportional control solenoid valve and the relative speed of the continuously variable control damper.

The required damping force Fs is composed of a tensile damping force FT required when the damper relative speed Ds is a positive number and a compression damping force FC which is a required damping force when the damper relative speed Ds is negative. The required damping force FT, FC is calculated only when the sign +/- of the required damping force Fs and the sign +/- of the damper relative movement speed Ds are equal.

The reference damper current Cd is calculated so as to correspond to the required damping force Fs and the damper relative moving speed Ds between the maximum current of 1300 mA and the minimum current of 300 mA. The reference damper current is applied to the continuous variable control damper proportional control solenoid valve to change the damper to a hard state when the vertical vibration velocity of the vehicle body is large. When the vertical vibration velocity of the vehicle body is low Apply a high current value to the damper solenoid valve to change the damper to a soft state.

For example, if the measured damper relative speed Ds is A and the required damping force Fs is B, then the reference damper current according to the damper relative speed Ds and the required damping force Fs is linear It is calculated using linear interpolation.

To this end, it is first determined (D3, D4) that the measured damper relative speed (Ds) is located, and by the linear interpolation using the smaller section (D3) The maximum damping force HA and the minimum damping force LA of the continuous variable control damper damping force characteristic corresponding to the velocity Ds are calculated.

Then, the reference damper current Cd corresponding to the required damping force B is calculated by applying the linear interpolation once again within the maximum damping force HA and the lowest damping force LA.

At this time, the difference between the current value applied to the current continuous variable control damper and the calculated reference damper current (Cd) is referred to as a reference current variation amount.

The allowable variation amount of the current to be applied to the proportional control solenoid valve of the continuously variable control damper depends on the absolute value | Ds | of the damper relative movement speed Ds (S3) using the linear interpolation from the allowable variation amount (Cca) curve of the damper current according to | Here, the allowable change amount Cca of the damper current is an amount to set the allowable range of the current reduction amount to decrease the damping force of the continuously variable control damper, that is, physically decrease based on the current value applied to the current continuously variable control damper.

For example, when the absolute value of the damper relative motion speed (| Ds |) is S, the allowable change amount Cca of the damper current is 700 mA.

Then, it is checked whether or not the change allowable amount is equal to the maximum change allowable amount (S4) by comparing the maximum change allowable amount which is the maximum value of the change allowable amount Cca and the change allowable amount Cca. Here, the maximum changeable amount is 1000 mA because of the difference between the maximum current (1300 mA) and the lowest current (300 mA) of the damper current.

When the change allowable amount Cca is equal to the maximum change allowable amount, the calculated reference damper current Cd is directly applied to the proportional control solenoid valve (S8) to increase the damping force, thereby suppressing the vibration generated in the vehicle body. That is, when the change allowable amount Cca is equal to the maximum change allowable amount (1000 mA), the current applied to the current proportional control solenoid valve is 1300 mA which is the maximum current, and even when the calculated reference damper current Cd is calculated as 300 mA, Since the allowable change amount (Cca) is 1000 mA, the reference damper current (Cd) of 300 mA is directly applied to the damper without limitation.

If the change allowable amount Cca is smaller than the maximum change allowable amount, it is checked whether the change allowable amount Cca is smaller than the reference current change amount by comparing the reference current change amount with the change allowable amount (S5).

When the change allowable amount (Cca) is equal to or larger than the reference current change amount, the reference damper current calculated without any limitation is applied to the proportional control solenoid valve (S8) to increase the damping force, thereby suppressing the vibration generated in the vehicle body.

On the other hand, when the change allowable amount Cca is smaller than the reference current change amount, the limited damper current that limits the calculated reference damper current is calculated (S6).

For example, assuming that the current change allowable amount Cca calculated from the relative moving speed of the currently measured continuous variable damper is 50 mA, the current value applied to the current proportional control solenoid valve is 1300 mA, and the reference damper current value Cd is 300 mA , The reference current change amount becomes 1000 mA.

If the limit is not limited by the allowable change amount Cca, the damper current must be changed from 1000 mA to 300 mA at 1300 mA. However, since the allowable change amount Cca calculated from the relative movement speed Ds of the continuous variable control damper is 80 mA, The current value that can be applied to the control solenoid valve is limited to 1250 mA, which is reduced by 50 mA, which is the change allowable amount (Cca) at 1300 mA.

In this manner, when the change allowable amount Cca is smaller than the reference current change amount Cd, it is possible to prevent unnecessary change of the current through the change allowable amount Cca. That is, it is possible to prevent the current from changing if the relative variable speed of the continuously variable control damper is very small through the change allowable amount Cca and the effective damping force can not be physically generated for vibration control of the vehicle body.

Then, the finally calculated limit damper current is applied to the proportional control solenoid valve (S7) to control the magnitude of the damping force generated from the continuously variable control damper.

It is to be understood that the present invention is not limited to the above-described embodiment, and that various modifications and variations of the present invention are possible in light of the above teachings. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Fs; Required damping force Cd; Reference damper current
Ds; Damper relative speed Cca; Change tolerance

Claims (4)

Calculating a required damping force for controlling up-and-down vibration of the vehicle body through a vertical vibration speed of the vehicle body;
Calculating a reference damper current from the damping force characteristic map of the continuously variable control damper using the required damping force and the damper relative moving velocity;
Calculating a changeable permissible amount from a current value applied to a current damper according to an absolute value of the damper relative movement speed;
Comparing a reference current change amount that is a difference between a current applied to the current damper and the reference damper current with the change allowable amount and calculating a limited damper current that limits the reference damper current when the change allowable amount is small; And
And applying the limiting damper current to the proportional control solenoid valve of the continuously variable control damper,
Wherein the control unit checks whether the change allowable amount is a maximum change allowable amount which is a maximum value of the change allowable amount and compares the reference current change amount and the change allowable amount when the change allowable amount is less than the maximum change allowable amount Wherein the step of controlling the continuous variable damper comprises the steps of: delete The method according to claim 1,
And applying the reference damper current to the proportional control solenoid valve of the continuously variable control damper when the change allowable amount is equal to the maximum change allowable amount. The method according to claim 1,
And applying the reference damper current to the proportional control solenoid valve of the continuously variable control damper when the change allowable amount is equal to or greater than the reference current change amount.

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