KR100445988B1 - Shock absorber using magnetorheological fluid - Google Patents

Abstract

The present invention discloses a shock absorber capable of adjusting the damping force using a magnetorheological fluid.

The present invention provides a first cylinder for storing a fluid having a fixed viscosity characteristic, a second cylinder provided with a magnetorheological fluid and installed inside the first cylinder, and a first space between the first cylinder and the second cylinder. A first piston installed in a donut shape so as to reciprocate in a portion, a second piston installed reciprocally in a second cylinder, and having a magnetic field magnetic field adjusting means installed therein so as to change the viscosity of the magnetorheological fluid; And a first piston rod inserted into the first space portion and fixedly coupled to the upper portion of the first piston, and a second piston rod inserted into the second space portion and fixed to the second piston to adjust the damping force. Attenuation by applying magneto-fluids and general fluids with excellent fluid stability to a single shock absorber so that each benefit can be used simultaneously It can significantly improve the performance and functionality of the shock absorber.

Description

Shock absorber using magnetorheological fluid {SHOCK ABSORBER USING MAGNETORHEOLOGICAL FLUID}

The present invention relates to a shock absorber using a magnetorheological fluid, a magnetorheological fluid capable of controlling the damping force and a general fluid having excellent fluid stability to a single shock absorber so as to utilize each of the advantages simultaneously. It relates to a shock absorber using.

Suspension device is mainly installed between the vehicle body and the axle to reduce the shock or vibration transmitted from the road surface while driving to improve the adhesion between the wheel and the road surface and to improve the riding comfort.

In particular, the shock absorber absorbs the free vibration of the spring generated on the road surface and improves the riding comfort. When the spring is compressed, the shock absorber is rapidly compressed and increases the resistance of the fluid when it is increased, and gradually increases the up and down kinetic energy of the spring. It converts into heat energy.

The shock absorber is a passive shock absorber that generates only a constant damping force initially set regardless of the external input, and a semi-active shock absorber that can change the damping force of the system according to the change of the external input. ) And an active shock absorber to reduce vibration by generating reaction forces to external inputs.

Among them, in consideration of performance vs. energy consumption, research and efforts have recently been conducted for semi-active shock absorbers having a performance which is significantly lower than that of an active shock absorber in comparison with an active shock absorber.

As part of this research and effort, a significant amount of damping devices using magnetorheological fluids, which are fluids that can be easily controlled among smart materials, have been developed.

A magnetorheological fluid is a non-colloidal solution containing micro paramagnetic particles. When the magnetic field is not applied, the magnetorheological fluid has a viscosity of 0.20 Pa-sec to 0.30 Pa-sec at room temperature and is 150 kPa / m to 250 kPa / m (2 kOe to 3 kOe). When a magnetic field of) is applied, it has a high yield stress of 50 kPa to 100 kPa. In addition, the magnetorheological fluid has a maximum response stress limited by magnetic saturation with a fast response time, and also has a characteristic insensitive to the operating range of -40 ° C to 150 ° C and impurities introduced.

The magnetorheological fluid having such a property changes from a liquid state to a gel state when a magnetic field is applied, and the particles contained in the fluid form a chain, thereby changing the shear yield stress of the fluid. In other words, when a magnetic field is not applied, the Newtonian fluid exhibits a behavior. However, when a magnetic field is applied, particles dispersed in the fluid form a chain and have a yield stress even in the absence of shear strain. This indicates the behavior of the Bingham fluid, in which the dissipated torque increases with increasing.

1 and 2 are cross-sectional views showing an example of a shock absorber using a conventional magnetorheological fluid.

As shown in FIG. 1, a piston 2 for generating a damping force of a shock absorber is installed inside an elongated cylindrical cylinder 1, and the piston 2 has a piston rod 3 penetrating the upper portion of the cylinder 1. ), It slides along the inner wall of the cylinder 1 so as to be able to move up and down. On the other hand, the magnetorheological fluid is filled in the cylinder 1.

The piston 2 has a spool shape, and a flange portion having a larger diameter is formed at the upper and lower portions, respectively, to form a structure capable of accommodating the coil 4 wound between the flange portions. The piston 2 is usually made of a magnetic material such as low carbon steel. On the other hand, the guide rail 5 is coupled to the outer periphery of the piston 2 at regular intervals. The maximum diameter of the piston (2) is formed smaller than the inner diameter of the cylinder (1), the outer surface of the guide rail (5) abuts the inner diameter of the cylinder (1). The guide rail 5 is formed of a nonmagnetic material, and a gap is formed between the piston 2 and the cylinder 1 by the guide rail 5, and the gap of the magnetorheological fluid passing through the piston 2 is formed. It performs a valve function to control the flow rate.

Meanwhile, as shown in FIG. 2, a hollow part 6 is formed inside the piston rod so that electrical connection means for applying a current to the coil 4 from outside the shock absorber can pass therethrough.

The shock absorber using the conventional magnetorheological fluid configured as described above is rapidly compressed when the spring is compressed by the free vibration of the spring generated on the road surface, and increases the resistance of the magnetorheological fluid when it is increased, and gradually operates it to heat up and down the kinetic energy of the spring. Attenuation using the behavior of the magnetorheological fluid mentioned above by varying the magnetic field formed around the piston 2 by adjusting the amount of current applied to the coil 4 in addition to performing a conventional damping function of The property can be varied.

However, the shock absorber using the magnetorheological fluid has an advantage in that the damping force can be controlled. However, the magnetorheological fluid has a disadvantage in that the basic property of the magnetorheological fluid is weaker than the basic viscosity of the general fluid currently used. The shock absorber using has a disadvantage in that it is difficult to be commercialized in comparison with the general shock absorber in terms of economical efficiency compared to damping performance.

Accordingly, the present invention is to solve such a conventional problem, to provide a shock absorber that improves the damping characteristics by using a magnetorheological fluid that can adjust the damping force and a conventional fluid having high damping performance at the same time having a high basic viscosity. Its purpose is to.

In the shock absorber that can adjust the damping force using the magnetorheological fluid, the present invention provides a first cylinder for storing a fluid having a fixed viscosity characteristic, and a magnetorheological fluid for storing the first cylinder. A second cylinder installed therein, a first piston installed in a donut shape so as to reciprocate in a first space between the first cylinder and the second cylinder, and reciprocally installed in the second cylinder, A second piston having a magnetic field magnetic field adjusting means installed therein so as to change the viscosity of the magnetorheological fluid, a first piston rod inserted into the first space and fixed to the upper portion of the first piston, and the second piston It provides a shock absorber using a magnetic variable fluid including a second piston rod inserted into the space portion and fixed to the second piston.

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the invention described below with reference to the accompanying drawings by those skilled in the art.

1 is a cross-sectional view showing a shock absorber using a conventional magnetorheological fluid,

Figure 2 is a cross-sectional view showing a coupling structure of a conventional piston and a piston rod,

3 is a cross-sectional view showing a shock absorber using a magnetorheological fluid according to the present invention;

4 is a perspective view showing a coupling structure of a piston and a piston rod according to the present invention;

5 is a cross-sectional view showing the internal structure of a second piston according to the present invention;

Figure 6 is a plan view of the top of the cylinder according to the present invention.

<Description of the symbols for the main parts of the drawings>

20; Cylinder assembly 21; First cylinder

22; Second cylinder 30; Piston rod assembly

31; First piston rod 32; Piston rod

33; Connecting member 40; First piston

50; Second piston 51; coil

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

3 is a cross-sectional view showing a shock absorber using a magnetorheological fluid according to the present invention, Figure 4 is a perspective view showing a piston rod assembly 30 and a piston according to the present invention, Figure 5 is a magnetorheological fluid according to the present invention It is sectional drawing which shows the piston for fluids.

As shown, the shock absorber using magnetorheological fluid according to the present invention consists of a cylinder assembly 20, a piston assembly and a piston rod assembly 30.

The cylinder assembly 20 according to the present invention comprises a first cylinder 21 in which a general fluid, that is, a fluid having fixed viscosity characteristics, is stored, and a magnetorheological fluid, that is, a fluid in which a driver can arbitrarily adjust the viscosity characteristic is stored. It consists of two cylinders 22. The second cylinder 22 is installed separately in the first cylinder 21, the first cylinder 21 and the second cylinder 22 is installed so that the flow of fluid to each other can be blocked.

The lower part of the cylinder assembly 20 is typically provided with an axle coupling portion 23 to be coupled to the axle.

The piston assembly consists of a first piston 40 coupled to the first cylinder 21 and a second piston 50 coupled to the second cylinder 22. Since the second cylinder 22 is inserted in the center of the first cylinder 21, the cross-sectional shape of the first space 24 has a donut shape. Thus, the first piston 40 forms a donut shape with a central portion drilled therein. The diameter of the hollow portion 41 bored in the center is formed at least larger than the outer diameter of the second cylinder 22. At one end of the first piston 40, a plurality of valve holes 42 through which fluid can pass in the longitudinal direction are formed in a conventional structure. The outer and inner circumferences of the first piston 40 respectively perturbed at the inner circumference of the first cylinder 21 and the outer circumference of the second cylinder 22 are respectively teflon to block the flow of fluid and to protect the perturbation surface. Conventional hermetic members 43 and 44 made of the same material are joined.

On the other hand, the second piston 50 is inserted into the second cylinder 22 is installed to be perturbed in the vertical direction. The second piston 50 is provided with a magnetic field adjusting means therein so that the viscosity characteristic of the magnetorheological fluid stored in the second cylinder 22 can be varied.

Magnetic field regulating means can be implemented through conventional solenoid structures. That is, the material of the second piston 50 may be formed of a magnetic material, and the strength of the magnetic field may be adjusted according to the magnitude of the current applied to the coil 51 by winding the coil 51 around the outer circumference thereof.

Referring to the structure of the second piston 50 in more detail, as shown in FIG. 5, the second piston 50 is made of a magnetic material of low carbon steel and has a larger diameter flange portion (top and bottom, respectively) 52 and 53 are formed to form a spool, and the coil 51 is wound between the flange portions 52 and 53. On the other hand, a valve hole 55 penetrating the upper and lower portions of the second piston 50 is formed so that a part of the magnetorheological fluid can pass through the valve hole 55. The outer circumference of the second piston 50, like the first piston 40, is combined with a conventional hermetic member 56 made of a material such as Teflon to block the flow of fluid and protect the perturbation surface. The second piston 50 has a magnetic field strength adjusted according to the amount of current applied to the coil 51 to affect the viscosity characteristics of the magnetorheological fluid passing through the valve hole 55.

The maximum diameter of the second piston 50 should be smaller than the inner diameter of the hollow part 41 formed at the center of the first piston 40, and the degree of perturbation of the inner circumferential surface of the second cylinder 22. It is formed in size.

As shown in FIG. 4, the piston rod assembly 30 performs vertical movement of the first piston 40 inserted into the first cylinder 21 and the second piston 50 inserted into the second cylinder 22. It forms a structure that can be integrated. That is, the first piston rod 31 inserted into the first space portion 23 and fixedly coupled to the upper portion of the first piston 40, and inserted into the second space portion 25 to the second piston 50. It consists of a second piston rod (32) fixedly coupled.

In the exemplary drawing, three sets of the first piston rod 31 are arranged on the same radius at equal intervals of 120 degrees, and the second piston rod 32 is formed in the concentric form of the three first piston rods 31. It has a single axis in the center. Such three first piston rods 31 and one second piston rod 32 are integrally coupled via a three-way connecting member 33 provided on the shaft of the second piston rod 32. Meanwhile, the first piston rod 31 is merely an example for stably fixing the first piston 40 having a donut shape, and the shape and number thereof may be changed or adjusted as necessary.

On the other hand, the electrical connection means for applying a current to the coil installed in the second piston 50 is not shown in the exemplary drawings according to the present invention, as shown in the conventional exemplary drawing 2, as shown in the piston rod By forming a hollow portion and extending the coil extension line through the hollow portion to the outside of the shock absorber can be implemented through a conventional structure to supply power from the outside.

On the other hand, Figure 6 is a plan view showing the upper portion of the cylinder according to the present invention, the center portion is formed with a hole 25 into which the second piston rod 32 is inserted, the same radius around the hole 25 Holes 27 into which the first piston rod 31 is inserted are formed at equal intervals of 120 degrees. Typically, at the inner circumference of the holes 26 and 27, airtight means 28 are provided to stably support the up and down piston rod assembly 30 and to prevent the general fluid and the magnetorheological fluid stored therein from leaking through the holes. Is installed.

The shock absorber using the magnetorheological fluid according to the present invention configured as described above uses a damping characteristic of a fluid having a fixed viscosity characteristic when converting the up and down kinetic energy of the spring of the spring generated on the road surface into thermal energy. It is possible to control the damping characteristic by adjusting the viscosity characteristic of the magnetorheological fluid by varying the magnetic field formed around the second piston 50 by adjusting the amount of current applied.

In other words, the damping characteristics of the shock absorber can be improved by using the excellent fluid with fixed viscosity characteristics so far, and the magnetorheological fluid can adjust the damping characteristics according to the driving conditions of the vehicle or the driver's choice.

Such a shock absorber using the magnetorheological fluid according to the present invention can significantly reduce the amount of expensive magnetorheological fluid used because the magnetorheological fluid is filled only inside the second cylinder 22 having a relatively small diameter. Therefore, the cost can be reduced.

In the above description, it should be understood that those skilled in the art can only make modifications and changes to the present invention without changing the gist of the present invention as it merely illustrates a preferred embodiment of the present invention.

As described above, according to the present invention, by applying a magnetorheological fluid capable of adjusting the damping force and a general fluid having excellent fluid stability to a single shock absorber, each of the advantages can be utilized at the same time, thereby improving the damping performance and the functionality of the shock absorber. The effect which can be improved significantly can be obtained.

Claims (7)

In shock absorber that can adjust damping force by using magnetorheological fluid, A first cylinder in which a fluid having a fixed viscosity characteristic is stored; A second cylinder in which the magnetorheological fluid is stored and installed in the first cylinder; A first piston installed in a donut shape so as to reciprocate in a first space portion between the first cylinder and the second cylinder; A second piston installed reciprocally in the second cylinder and having a magnetic field magnetic field adjusting means installed therein to change the viscosity of the magnetorheological fluid; A first piston rod inserted into the first space and fixed to an upper portion of the first piston; A shock absorber using a magnetorheological fluid including a second piston rod inserted into the second space and fixedly coupled to a second piston. The shock absorber using magnetorheological fluid according to claim 1, wherein the first cylinder and the second cylinder are installed to block the flow of the fluid. The shock absorber using magnetorheological fluid according to claim 1, wherein the diameter of the hollow part of the first piston is at least larger than the outer diameter of the second cylinder (22). 2. The shock absorber using magnetorheological fluid according to claim 1, wherein an airtight member is coupled to an outer circumference and an inner circumference of the first piston to respectively block the flow of the fluid and to protect the perturbation surface. The method of claim 1, wherein the magnetic field adjusting means is formed so that the material of the second piston is formed of a magnetic material, and the coil is wound around its outer circumference to adjust the strength of the magnetic field according to the magnitude of the current applied to the coil. Shock absorber using a magnetorheological fluid, characterized in that. The method of claim 1, wherein the maximum diameter of the second piston is smaller than the inner diameter of the hole formed in the central portion of the first piston, characterized in that the size formed so as to perturb the inner peripheral surface of the second cylinder. Shock absorber using magnetorheological fluid. The shock absorber according to claim 1, wherein the piston rod assembly is integrally coupled through a three-way connecting member installed on the shaft of the second piston rod.