KR20020095660A - Bracket with dynamic damper using MR fluid - Google Patents

Abstract

PURPOSE: A bracket equipped with a dynamic damper, using MR(Magneto-rheological) fluids is provided to meet a complex characteristic capable of efficiently shutting off high frequency vibration component while having efficient support stiffness at low frequency. CONSTITUTION: A bracket(10) equipped with a dynamic damper(20), using MR fluids(21) comprises a rubber case(22) installed to a side of the side, MR fluids stored in the case, a housing(23) connected to the case, and an electromagnet(24), installed inside the housing. The electromagnet receives voltage according to the output value from an ECU(40) of receiving a signal from an acceleration sensor(30) and then calculating vibration value, and gives magnetic field to the MR fluids. The bracket can be simplified, lightened, and miniaturized, since just the electromagnet for giving magnetic field, to control damping force, is added without using many machine elements.

Description

Bracket with dynamic damper using MRR fluid {Bracket with dynamic damper using MR fluid}

The present invention relates to a bracket used for mounting an engine or a transmission of an automobile, and more particularly, to a bracket provided with a dynamic damper using a magneto-rheological (MR) fluid.

In general, the anti-vibration bracket used in a vehicle or a mechanical structure is to reduce the noise and vibration by supporting between the excitation circle and the structure while minimizing the transmission force from the excitation circle to the structure.

As such, the bracket should theoretically have low rigidity in order to increase vibration damping force, while the design conditions should be given to satisfy the contrary requirement to maintain static support rigidity in order to support the load of the excitation circle.

However, polymer materials commonly used, such as rubber, which are dustproof materials alone, cannot satisfy the above two requirements. Also, the performance required for vehicles or mechanical structures has recently changed to higher quality functions such as improved ride comfort and precision driving. There was a problem that can not meet the trend.

For example, the engine or transmission of an automobile includes a periodic change of the center position due to the vertical movement of the piston and the connecting rod, the inertial force of the reciprocating portion occurring in the cylinder axial direction, the inertial force caused by the connecting rod swinging from the left and right of the crankshaft, Periodically changes in the rotational force applied to the crankshaft are constantly vibrated structurally.

Therefore, the engine or the transmission is installed in the vehicle body via the anti-vibration bracket, the bracket is to support the role and to insulate the vibration.

In terms of vibration, when the vibration occurs in the engine or transmission, it is transmitted to the vehicle body through the bracket. When the natural frequency of the bracket and the frequency of the vibration component coincide, the vibration is amplified. The natural frequency of the bracket is designed to be larger than the frequency range of the vibration generated at, or the dynamic damper is used to reduce the vibration in question.

Here, conventionally, an ER (elector rheological) fluid is mainly used as a dynamic damper. As ER fluid is used, the following problems occur.

First, since an electrode must be installed directly inside the ER fluid case to directly contact the electrode with the ER fluid, problems with the electrode insertion structure, ER fluid case sealing problems that may occur when the electrode is inserted, and problems in manufacturing the ER fluid case are difficult. do.

Second, a high voltage power supply is needed to drive the ER fluid.

Accordingly, the present invention has been made to solve the above problems, and provides a bracket with a dynamic damper that satisfies the complex characteristics that can sufficiently block the high-frequency vibration components while having sufficient support stiffness at low frequencies There is a purpose.

Another object of the present invention is to provide a bracket having a dynamic damper using a magneto-rheological (MR) fluid.

1 is a schematic diagram showing an installation state of a bracket provided with a dynamic damper according to the present invention;

2 is an operation flowchart of a bracket according to the present invention;

3A, 3B and 3C are graphs showing a state in which vibration is reduced by the bracket according to the present invention.

Explanation of symbols on the main parts of the drawings

10: bracket 20: dynamic damper

21: MR fluid 22: case

23 housing 24 electromagnet

30: acceleration sensor 40: ECU

In order to achieve the above object, the present invention, in the bracket for connecting the vehicle body mount and the engine, characterized in that the dynamic damper is installed on one side of the bracket.

In addition, the present invention is characterized in that the MR fluid is used in the dynamic damper.

To this end, the present invention provides a magnetic field to the MR fluid of the case according to the bracket, the case attached to one side of the bracket and the MR fluid is filled, the acceleration sensor and ECU for calculating the vibration amount of the engine, etc., and the signal of the ECU It includes an electromagnet for application.

On the other hand, looking at the vibration damping method of the bracket having the structure as described above, measuring the vibration speed applied to the bracket, calculating the frequency through the measured acceleration, determining the maximum vibration frequency, maximum vibration Calculating the spring coefficient and damping value of the dynamic damper which can cancel the vibration at the generated frequency, calculating the strength of the voltage corresponding to the calculated spring coefficient and the damping value, and applying the calculated voltage to the electromagnet Attenuating the vibration by varying the vibration damping force of the made.

Hereinafter, the present invention will be described in detail with reference to the flowchart of FIG. 2.

1 is a schematic diagram showing an installation state of a bracket provided with a dynamic damper according to the present invention.

According to the drawings, the present invention is a bracket 10 is connected between the engine and the mount of the vehicle body, the bracket is a dynamic damper 20 attached to the side, the mass imposed on the dynamic damper, for detecting the vibration of the bracket The acceleration sensor 30 includes an ECU 40 for receiving a signal from the acceleration sensor, processing the signal, and applying a voltage to the dynamic damper.

Here, the dynamic damper 20 is attached to one side of the bracket and the case 22 filled with MR fluid 21 therein, a housing 23 connected to the case and made of mass, and installed inside the housing and the ECU It comprises an electromagnet for applying a corresponding voltage from 40 to apply a magnetic field to the MR fluid.

The MR fluid 21 has a characteristic that the viscosity (yield stress) changes with the change of the magnetic field. Therefore, the MR fluid changes viscosity and spring coefficient according to the strength of the magnetic field that is changed by voltage.

The case 22 is preferably made of a rubber material.

In addition, the electromagnet 24 has a structure in which a conductive coil is wound around the iron core, and one pole is installed in the housing 23 in a direction toward the case to apply a magnetic field to the MR fluid.

The housing 23 serves as a mass of the dynamic damper 20 in addition to supporting the electromagnet.

Hereinafter, the operation of the present invention will be described with reference to the flowchart of FIG. 2.

When the engine or transmission is operated, vibration is generated, and the vibration is transmitted to the vehicle body through the bracket 10.

The vibration transmitted through the bracket 10 is measured by the acceleration sensor 30 installed on the bracket 10 side. The vibration data thus measured is input to the ECU 40.

The ECU 40 calculates the frequency of the maximum vibration component by converting the time axis among the vibration components to the frequency axis (FFT; Fast FouriMR Transform), and calculates vibration of the engine or transmission through the bracket 10 based on the calculated frequency. The spring coefficient and the damping value of the dynamic damper 20 can be calculated as much as possible.

Next, the ECU 40 calculates a voltage to be added to the electromagnet 24 according to the calculated value, and applies the voltage to the electromagnet installed in the housing 23.

As a current is applied to the conductive coil surrounding the iron core of the electromagnet 24, a magnetic field is induced around the coil, and the magnetic field induced by the current forms a closed circuit, that is, a magnetic field line.

The magnetic force line flows through the MR fluid 21 flowing with the bracket 10, and thus the vibration damping force of the MR fluid is varied as the magnetic field acts on the MR fluid.

That is, when the current value applied to the coil is changed according to the magnitude of vibration transmitted from the excitation source, the intensity of the magnetic field induced in the coil is changed, and the viscosity of the MR fluid 21 is changed according to the strength of the magnetic field. The fluid has a spring coefficient and viscosity that can reduce the vibration of the bracket 10 as much as possible. Therefore, the vibration from the excitation source can be effectively attenuated.

For example, when the vibration component of the bracket has a low frequency, the strength of the magnetic field acting on the MR fluid is weakened so that the dynamic damper is set to attenuate the vibration in the low frequency region (see FIG. 3A).

In addition, when the vibration component of the bracket has a high frequency, the magnetic field acting on the MR fluid is strengthened so that the vibration can be attenuated in the high frequency region of the dynamic damper (see FIG. 3B).

In addition, the vibration mode (bracket) mode of the bracket is present over a variety of frequencies, the vibration by each vibration mode can be continuously attenuated by adjusting the magnetic field applied to the MR fluid from the electromagnet. The graph for this is well illustrated in FIG. 3C.

According to the bracket provided with the dynamic damper according to the present invention as described above, not only the performance is excellent, but also the use of only the electromagnet for applying the magnetic field for the damping force control without using many mechanical elements, simplifying the device. . It is possible to reduce the weight and size, and the price is low and the possibility of failure is greatly reduced.

In addition, it generates a wide range of continuous attenuation, low power consumption of several watts (Watt) and has a fast response speed of 1 to 2 msec.

In addition, the structure of the MR fluid case is simple because the MR fluid is sealed in the MR fluid case.

In addition, since it is possible to control the characteristics of the dynamic damper at a lower voltage compared to the case of using the ER fluid, it is easy to control and less sensitive to temperature, so there is an advantage that it can be used without correction to a certain temperature change.

Claims (1)

In the bracket connected between the engine and the mount of the vehicle body, The bracket is a rubber case attached to the side, MR fluid filled inside the case, a housing connected to the case and made of a mass, a housing installed inside the housing and receiving a signal from the acceleration sensor to calculate the vibration value. Bracket having a dynamic damper using the MR fluid further comprising a dynamic damper including an electromagnet for applying a magnetic field to the MR fluid by applying a voltage according to the.