KR20120002756A - Control method of continuously controllable damper - Google Patents

Abstract

PURPOSE: A method for controlling continuously controllable damper is provided to prevent unnecessary or rapid change of damper current. CONSTITUTION: A method for controlling continuously controllable damper comprises: a step of calculating demanded damping force for controlling upper/lower vibration of an automobile(S1); a step of calculating standard damper current using the demanded damping force and damper relative movement speed(S2); a step of calculating changeable acceptance from the current value applied in a present damper(S3); a step of comparing the standard change amount and changeable acceptance and calculating limit damper current in case that the changeable acceptance is little(S4); and a step of applying the limit damper current with proportionally controller solenoid valve(S7).

Description

Control method of continuous variable control damper {CONTROL METHOD OF CONTINUOUSLY CONTROLLABLE DAMPER}

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 for preventing unnecessary control by limiting a change in current applied to the continuously variable control damper according to the relative speed of the damper. .

Recently, the application of a continuously variable control damper is increasing in order to improve the driver's riding comfort and steering stability around high-end models. Continuously variable control damper is a form of adding a proportional control solenoid valve that can adjust the opening and closing degree of the flow path according to the amount of current applied to the general hydraulic damper. Therefore, when the relative movement between the vehicle body and the wheel, that is, vibration occurs, the damping force is controlled by controlling the differential pressure applied to the piston by controlling the flow path of oil flowing between the upper and lower chambers centered on the piston connected to the damper rod. It is a principle that can control the size of and reduce the unnecessary vibration of the car body accordingly.

Here, reference values for calculating a current to be applied to the proportional control solenoid valve of the continuously variable control damper are shown in FIG. 1.

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

As shown in FIG. 1, if the required damping force Fs calculated from the vertical velocity of the vehicle body is Fa, and the relative movement speed Ds of the continuously variable control damper measured at this time is a, in this case, the lowest current ( Even if 300mA) is applied, it is impossible to generate the damping force Fa required by the system, and the physically possible damping force is much less Fb than Fa, so that effective control results cannot be obtained.

In other words, when the relative motion speed Ds of the damper is very small, a large current may be calculated mathematically to obtain a value closest to the required damping force Fs even though a large damping force cannot be obtained according to the current change. Frequently, this usually results in a sharp current change from the maximum current to the lowest current value, which can lead to a deterioration of the operating noise or mechanical durability of the valve, which can adversely affect the system.

SUMMARY OF THE INVENTION The present invention is to overcome the above-mentioned problems, and an object of the present invention is to limit the allowable amount of change in the applied current according to the relative movement speed of the continuously variable control damper, thereby generating an effective damping force by preventing unnecessary current change. The present invention provides a control method that can prevent the noise or mechanical durability of the proportional control solenoid valve from deteriorating due to a sudden change in the current.

In order to achieve the above object, the control method of the continuously variable control damper according to the present invention comprises the steps of calculating the required damping force for controlling the vertical vibration of the vehicle body through the vertical vibration speed of the vehicle body, and the required damping force and the damper relative movement speed Calculating a reference damper current from the damping force characteristic map of the continuously variable control damper, calculating a change allowable amount from a current value currently applied to the damper according to the absolute value of the relative damper movement speed; Calculating a limiting damper current for limiting the reference damper current when the change allowable amount is small by comparing a reference change amount that is a difference between a current being applied to the current damper and the reference damper current, and the change allowable amount; Proportional control solenoid valve of the continuous variable control damper to limit the damper current It may comprise the step of applying.

After calculating the change allowance, checking whether the change allowance is a maximum change allowance that is a maximum value of the change allowance, and comparing the reference change amount with the change allowance when the change allowance is less than the maximum change allowance. You can run

If the change allowance is equal to the maximum change allowance, the step of applying the reference damper current to the proportional control solenoid valve of the continuously variable control damper may be performed.

When the change allowance is equal to or greater than the change amount of the reference current, applying the reference damper current to the proportional control solenoid valve of the continuously variable control damper may be performed.

The control method of the continuously variable control damper according to the present invention is to limit the amount of current to be applied to the proportional control solenoid valve of the continuously variable control damper according to the relative movement speed of the continuously variable control damper to maintain the body vibration control performance and at the same time to prevent unnecessary current changes. This prevents noise and mechanical durability deterioration of the proportional control solenoid valve due to rapid current changes.

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 control method of a continuously variable control damper according to an exemplary embodiment of the present invention.
3 is a reference value for damper current in the method of controlling the continuously variable control damper of FIG. 2.
4 is a reference value of a change allowable amount in the control method of the continuously variable control damper of FIG. 2.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. Here, parts having similar configurations and operations throughout the specification are denoted by the same reference numerals.

2 is a flowchart illustrating a control method of a continuously variable control damper according to an embodiment of the present invention.

As shown in FIG. 2, the control method of the continuously variable control damper first calculates the required damping force for controlling the vertical vibration of the vehicle body by using the vertical vibration velocity value of the vehicle body based on a virtual fixed coordinate above the vehicle body. (S1). This required damping force is calculated through Equation 1.

Where Fs is the required damping force, Cs is the control gain, and Zs is the vertical vibration displacement of the vehicle body. That is, the required damping force Fs may be calculated as a product of the control gain Cs according to the running speed of the vehicle and the rate of change dZs / dt of vertical vibration displacement over time of the vehicle body, that is, the vertical vibration speed. Herein, the control gain Cs according to the traveling speed of the vehicle is a value stored separately in the controller, and is the same when the traveling 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 the linear interpolation method using the relative damping force Fs and the relative movement speed of the continuously variable control damper mounted to control the vertical vibration of the vehicle body. This reference damper current is applied to the solenoid valve which proportionally controls the opening and closing degree of the oil flow path in the continuously variable control damper in order to control the damping force of the continuously variable control damper. This reference damper current is calculated from FIG. 3, which is a characteristic map of the damping force characteristic of the continuously variable control damper previously measured according to the amount of current applied to the proportional control solenoid valve and the relative movement speed of the continuously variable control damper.

Here, the required damping force Fs is comprised of the tensile damping force FT which is the required damping force when the damper relative movement speed Ds is positive and the compression damping force FC which is the required damping force when the damper relative movement speed Ds is negative. The required damping forces FT and FC are calculated only when the sign (+/-) of the required damping force Fs and the sign (+/-) of the damper relative movement speed Ds are the same.

The reference damper current Cd is calculated to correspond to the required damping force Fs and the damper relative movement speed Ds between 1300 mA of maximum current and 300 mA of minimum current. This reference damper current is applied to a continuously variable control damper proportional control solenoid valve with a low current value that changes the damper to a hard state when the upper and lower vibration speeds of the vehicle body is large, and when the vertical vibration speed of the vehicle body is small. A high current value is applied to the damper solenoid valve that changes the damper to a soft state.

For example, when the measured damper relative movement speed Ds is A and the required damping force Fs is B, the reference damper current according to the damper relative movement speed Ds and the required damping force Fs is linear. Calculated using linear interpolation.

To this end, first, the sections in which the measured damper relative motion speed Ds is located are determined (D3 and D4), and the measured damper relative motion is measured by linear interpolation using the small section D3 and the large section D4. The maximum damping force HA and the lowest damping force LA of the continuously variable control damper damping force characteristic corresponding to the speed Ds are calculated.

In addition, linear interpolation is applied once again within the maximum damping force HA and the minimum damping force LA to calculate a reference damper current Cd corresponding to the required damping force B. FIG.

At this time, the difference between the current value currently applied to the continuously variable control damper and the calculated reference damper current Cd is referred to as the reference current change amount.

The allowable amount of change of the current to be applied to the proportional control solenoid valve of the continuously variable control damper according to the absolute value (| Ds |) of the damper relative movement speed Ds is the absolute value (| Ds) of the damper relative movement speed shown in FIG. (S3) is calculated using linear interpolation from the change allowance (Cca) curve of the damper current according to |). Herein, the change allowance amount Cca of the damper current is a quantity that sets the allowable range of the current reduction amount to decrease the current value applied to the continuously variable control damper, that is, to physically increase the damping force of the continuously variable control damper.

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

Then, it is checked whether the change allowable amount is equal to the maximum change allowable amount by comparing with the maximum change allowable amount which is the maximum value of the change allowable amount Cca and the change allowable amount Cca (S4). Here, the maximum allowable change amount is 1000 mA by the difference between the maximum current (1300 mA) and the minimum 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 applied to the proportional control solenoid valve as it is (S8) to increase the damping force to suppress vibration generated in the vehicle body. That is, when the change allowable amount Cca is equal to the maximum change allowable amount (1000 mA), even when the current being applied to the proportional control solenoid valve is 1300 mA, which is the maximum current, and the calculated reference damper current Cd is calculated to be 300 mA, Since the change allowable amount Cca is 1000 mA, without limitation, 300 mA, which is the reference damper current Cd, is applied to the damper as it is.

When 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 and the change allowable amount (S5).

If the change allowance Cca is equal to or greater than the change amount of the reference current, the vibration generated in the vehicle body is suppressed by increasing the damping force by applying the calculated reference damper current to the proportional control solenoid valve (S8) without any limitation.

On the contrary, when the change allowable amount Cca is smaller than the reference current change amount, the limited damper current limiting the calculated reference damper current is calculated (S6).

For example, the current change allowable amount Cca calculated from the relative movement speed of the continuously variable control damper currently measured is 50 mA, the current value currently being applied to the proportional control solenoid valve is 1300 mA, and the reference damper current value Cd is 300 mA. If so, the reference current change amount is 1000 mA.

If not limited by the change allowance (Cca), the damper current should vary by 1000 mA from 1300 mA to 300 mA, but the change allowance (Cca) calculated from the relative movement speed (Ds) of the continuously variable control damper is actually 80% The current value that can be applied to the control solenoid valve is limited to 1250mA, which is reduced by 50mA, the change allowance (Cca).

As described above, when the change allowance Cca is smaller than the reference current change amount Cd, the change of the unnecessary current can be prevented through the change allowance Cca. That is, the change allowance Cca can prevent the current from changing when the relative variable speed of the continuously variable control damper is very small so that an effective damping force cannot be generated physically for the vibration control of the vehicle body.

Finally, the calculated 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.

What has been described above is just one embodiment for carrying out the control method of the continuous variable control damper according to the present invention, and the present invention is not limited to the above-described embodiment, as claimed in the following claims. Without departing from the gist of the invention, anyone of ordinary skill in the art to which the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

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

Claims (4)

Calculating a required damping force for controlling the vertical vibration of the vehicle body through the vertical vibration velocity 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 movement speed;
Calculating a changeable change amount from a current value currently applied to the damper according to the absolute value of the damper relative movement speed;
Comparing a reference change amount which is a difference between the current being applied to the current damper and the reference damper current and the change allowance amount, and calculating a limit damper current limiting the reference damper current when the change allowance amount is small; And
And applying the limiting damper current to a proportional control solenoid valve of the continuously variable control damper. The method according to claim 1,
After calculating the change allowance, checking whether the change allowance is a maximum change allowance that is a maximum value of the change allowance, and comparing the reference change amount with the change allowance when the change allowance is less than the maximum change allowance. Control method of a continuous variable control damper, characterized in that for executing. The method according to claim 2,
And applying the reference damper current to the proportional control solenoid valve of the continuous variable control damper if 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 continuous variable control damper when the change allowable amount is equal to or greater than the reference current change amount.

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