KR100445987B1 - 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 relates to a cylinder assembly comprising: a first cylinder portion (fixed fluid portion) in which a fluid having fixed viscosity characteristics is stored, and a second cylinder portion in which magnetorheological fluid is stored; A piston rod assembly having a first rod portion, a second rod portion, a magnetorheological fluid chamber and a variable fluid inlet passage; A body part made of a magnetic material is coupled to a lower end of the second rod part and installed to perturb in the second cylinder, and a fixed fluid passage through which a fixed fluid can pass and a magnetorheological fluid can pass through one end of the body part. Rheological fluid flow paths are formed independently of each other, and a magnetic field adjusting means is installed to change the viscosity of the magnetorheological fluid passing through the magnetorheological fluid flow path. By applying to, the attenuation performance and shock absorber functionality can be greatly improved by allowing each benefit to be utilized simultaneously.

Description

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

The present invention relates to a shock absorber using a magnetorheological fluid, by applying a general fluid having excellent damping performance to a single shock absorber at the same time by applying a magnetorheological fluid capable of controlling damping force and a high basic viscosity. It relates to shock absorbers using magnetorheological fluids.

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. In addition to performing the normal damping function of converting the current to the coil 4, by controlling the amount of current applied to the coil 4 by varying the magnetic field formed around the piston (2) by using the behavior of the magnetorheological fluid mentioned above Can be changed.

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.

Therefore, the present invention is to solve such a conventional problem, a shock absorber that improves the damping characteristics by using a magnetorheological fluid that can adjust the damping force and the normal viscosity of the fluid with excellent damping performance at the same time to improve the damping characteristics The purpose is to provide.

In the shock absorber that can adjust the damping force using the magnetorheological fluid, the present invention provides a first cylinder part (fixed fluid part) and a magnetorheological fluid in which a fluid having a fixed viscosity characteristic is stored. A cylinder assembly, the cylinder assembly being divided into a second cylinder portion, the diameter of the second cylinder portion being larger than that of the first cylinder portion (magnetic fluid flow portion) and fixed to one end of the axle; A first rod part which is fixed to one end of the vehicle body through the upper part of the cylinder assembly, a second rod part which is formed in a straight line with the first rod part and is installed to be perturbable inside the first cylinder part, and an end of the second rod part A piston rod assembly comprising a magnetorheological fluid chamber coupled to the variable fluid flow path, and a variable fluid inflow passage formed in the second rod portion in a longitudinal direction; The body part made of magnetic material is coupled to the bottom of the second rod part and installed to perturb in the second cylinder, and the fixed fluid flow path through which the fixed fluid passes and the magnetorheological fluid through which the fixed fluid passes through one end of the body part. Provided is a shock absorber using a magnetorheological fluid, the fluid flow paths being formed independently of each other and including a piston assembly having magnetic field control means installed to change the viscosity of the magnetorheological fluid passing through the magnetorheological fluid flow path.

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 of a piston rod assembly according to the present invention;

5 is a sectional view showing a piston assembly according to the present invention;

6 is a cross-sectional view showing another embodiment of a piston assembly according to the present invention;

7 and 8 are cross-sectional views showing the operation of the shock absorber using the magnetorheological fluid according to the present invention.

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

20; Cylinder assembly 21; 1st cylinder part

22; Second cylinder portion 30; Piston rod assembly

31; A first rod part 32; 2nd rod part

33; Magnetorheological fluid chamber 34; Magnetorheological fluid inflow passage

35; Stepped section 40; Piston assembly

41; Body part 42; Fixed fluid flow path

43; Magnetorheological fluid path 44; 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 according to the present invention, Figure 5 is a cross-sectional view showing a piston assembly according to the present invention. 6 is a cross-sectional view showing another embodiment of the piston assembly according to the present invention.

As shown, the shock absorber using magnetorheological fluid according to the present invention consists of a cylinder assembly 20, a piston assembly 40 and a piston rod assembly 30.

The cylinder assembly 20 according to the present invention is a fluid generally used, that is, a first cylinder portion 21 in which a fluid having a fixed viscosity characteristic is stored, and a magnetorheological fluid, that is, a fluid capable of arbitrarily adjusting the viscosity characteristic. Is divided into a second cylinder portion 22 in which the first cylinder portion 21, that is, the fixed fluid portion 21 is smaller than the diameter of the second cylinder portion 22, that is, the magnetorheological fluid portion 22. Is formed larger. In addition, the fixed fluid portion 21 and the magnetorheological fluid portion 22 are blocked by the airtight means 23 so as not to mix with each other.

On the other hand, the outer cylinder portion 24 is installed to maintain a predetermined space along the outer circumference of the cylinder assembly 20, the lower portion of the cylinder assembly 20, the outer cylinder 24 during the damping action of the fluid of the fixed fluid portion 21 And a conventional base valve 25 structure that allows movement to the space between the cylinder assembly and the cylinder assembly 20. In addition, the lower end of the cylinder assembly 20 is typically provided with an axle coupling portion 26 to be coupled to the axle.

The piston rod assembly 30 according to the present invention is formed in a straight line with the first rod portion 31 and the first rod portion 31 fixed to one end of the vehicle body through the upper portion of the cylinder assembly 20. The second rod part 32 installed to be perturbable in the cylinder part 22, the magnetorheological fluid chamber 33 coupled to the end of the second rod part 32, and the second rod part 32. It consists of a magnetorheological fluid inlet passage 34 formed in the longitudinal direction. As shown, the diameter of the second rod portion 32 is formed to be similar to or slightly smaller than the inner diameter of the second cylinder portion 22, and the first rod portion 31 is smaller than the diameter of the second rod portion 32. It is made smaller so that the volume change of the second cylinder portion 22 occurs during the vertical movement of the piston rod assembly 30.

On the other hand, the magnetorheological fluid inflow passage 34 serves as a passage connecting the magnetorheological fluid stored in the second cylinder portion 22 to be introduced into the piston assembly 40, the first rod portion 31 A plurality of stepped portions 35 are formed at regular intervals by the difference in diameter between the second rod portion 32 and the second rod portion 32.

On the other hand, the magnetorheological fluid chamber 33 is screwed to the end of the second rod portion 32 is interlocked with the piston rod assembly 30, a space portion for storing the magnetorheological fluid therein is formed a second When the cylinder part 22 is compressed, the magnetorheological fluid can be stored in the magnetorheological fluid chamber 33 having a relatively low pressure via the magnetorheological fluid inflow path 34 and the piston assembly 40.

The piston assembly 40 according to the present invention has a body portion 41 having a diameter similar to or slightly smaller than the inner diameter of the second cylinder portion 22 so as to be perturbable within the second cylinder portion 22. The 41 is coupled to the lower end of the second rod part 32 and is located between the second rod part 32 and the magnetorheological fluid chamber 33. In addition, the material of the body portion 41 is preferably made of a magnetic material such as low carbon steel.

At one end of the body portion 41, the fixed fluid flow path 42 through which the fixed fluid can pass and the magnetorheological fluid flow path 43 through which the magnetorheological fluid can pass are formed independently of each other, and the body part 41 The magnetic field control means is installed in the inside of the circumference to change the viscosity of the magnetorheological fluid passing through the magnetorheological fluid flow path 44.

Magnetic field regulating means can be implemented through conventional solenoid structures. That is, by winding the coil 44 inside the body portion 41 made of a magnetic material, the strength of the magnetic field may be adjusted according to the magnitude of the current applied to the coil 44. On the other hand, the outer periphery of the body portion 41 is coupled to the conventional hermetic member 45 made of a material such as Teflon to block the flow of fluid and protect the perturbation surface. Therefore, the intensity of the magnetic field is adjusted according to the amount of current applied to the coil 44 to affect the viscosity characteristics of the magnetorheological fluid passing through the magnetorheological fluid passage 43.

Figure 5 is a cross-sectional view taken along the line AA 'of Figure 3 in accordance with the present invention, showing a cross section of the piston assembly. As shown, the piston assembly 40 is formed in a disk shape having a thickness, the center portion is formed with a hole 46 through which the end of the second piston rod 32 can be penetrated, the same half from the center The fixed fluid flow path 42 is formed in a 120 degree space | interval on a mirror, and the coil 44 is wound concentrically in the outer part. In addition, three magnetorheological fluid passages 43 are formed on the concentric circles outwardly of the coil 44, and each magnetorheological fluid passage 43 is connected to the hole 46 formed at the center thereof. Is provided. Therefore, it is in communication with the magnetorheological fluid inflow passage 34 formed in the second piston rod 32. On the other hand, the number and shape of the fixed fluid flow path 42 and the magnetorheological fluid flow path 43 may be adjusted or changed as necessary. For example, as shown in FIG. 6, in order to maximize the influence of the magnetic field, the magnetorheological fluid flow path 48 may be shaped like a slot. Meanwhile, the non-described 45 is a conventional hermetic member 45 made of Teflon or the like which is coupled to block the flow of fluid between the piston assembly 40 and the inner wall surface of the second cylinder portion 22 and to protect the perturbation surface. )to be.

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. By controlling the amount of current applied to vary the magnetic field formed around the piston assembly 40, it is possible to adjust the attenuation characteristic by adjusting the viscosity characteristic of the jogging rheology fluid passing through the magnetorheological fluid passage 43.

7 and 8 are cross-sectional views showing the operation of the shock absorber using the magnetorheological fluid according to the present invention. FIG. 7 shows the behavior during compression movement of the shock absorber, and FIG. 8 shows the behavior during extension (rebound) movement.

As shown in FIG. 7, the volume of the first cylinder portion 31 and the second cylinder portion 32 decreases as the piston rod assembly 30 is relatively raised with respect to the cylinder assembly 20 during the compression movement. The magnetorheological fluid and the fixed fluid flow out in the direction of the arrow, respectively, and perform attenuation functions.

At this time, when a certain amount of current is applied to the coil 44, a magnetic field is formed in the body portion 41 of the piston assembly 40 to change the viscosity characteristics of the magnetorheological fluid passing through the magnetorheological fluid passage 43. Can give In other words, as the amount of current applied to the coil 44 is increased, the viscosity of the magnetorheological fluid is increased to increase the damping force.

Meanwhile, as shown in FIG. 8, the piston rod assembly 30 is lowered relative to the cylinder assembly 32 during the extension movement, so that the volume of the first cylinder portion 31 and the second cylinder portion 32 decreases. As it grows, the magnetorheological fluid and the fixed fluid flow out in the direction of the arrow, respectively, and perform attenuation functions.

At this time, when a large amount of current is applied to the coil 44, the strength of the magnetic field formed in the body portion 41 is large, the viscosity of the magnetorheological fluid passing through the magnetorheological fluid flow path 43 is increased, thereby increasing the damping force. .

The shock absorber using the magnetorheological fluid according to the present invention is an expensive magnetorheological fluid that is used because the magnetorheological fluid is filled only in the second cylinder part 22 and the magnetorheological fluid chamber 33 having a relatively small diameter. The amount of can be significantly reduced, resulting in cost savings.

In addition, it is possible to increase the overall damping characteristics of shock absorbers by using excellent fluids 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. Can be used at the same time.

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 and a general fluid that can control the damping force to a single shock absorber, each advantage can be utilized simultaneously, thereby greatly improving the damping performance and the functionality of the shock absorber. You can get the effect.

Claims (1)

In shock absorber that can adjust damping force by using magnetorheological fluid, It is divided into a first cylinder part (fixed fluid part) in which a fluid having a fixed viscosity characteristic is stored and a second cylinder part in which magnetorheological fluid is stored, and a diameter of the second cylinder part is larger than that of the first cylinder part (magnetic fluid fluid part). A cylinder assembly largely formed and fixed to one end of the axle; A first rod part fixed to one end of the vehicle body through the upper part of the cylinder assembly, a second rod part formed in a line with the first rod part and installed to be perturbable inside the first cylinder part, and the second A piston rod assembly including a magnetorheological fluid chamber coupled to an end of the rod portion, and a variable fluid inlet passage formed in a lengthwise direction inside the second rod portion; A body part made of magnetic material is coupled to a lower end of the second rod part and installed to perturb in the second cylinder. A fixed fluid passage through which a fixed fluid can pass and a magnetorheological fluid can pass through one end of the body part. 10. A shock absorber using a magnetorheological fluid comprising a piston assembly having magnetorheological fluid flow paths formed independently of each other and provided with magnetic field control means for changing the viscosity of the magnetorheological fluid passing through the magnetorheological fluid flow path.