KR101257348B1 - 2 stage friction damper using shape memory alloy - Google Patents

Abstract

The present invention is a cylinder having a predetermined space therein; A piston rod moving longitudinally in the cylinder; A friction member friction with an outer circumferential surface of the piston rod to generate a damping force; A friction member receiver formed in the cylinder to accommodate the friction member; And a fixing member which is lifted up and down in a direction perpendicular to the piston rod to fix the friction member inside the friction member receiving portion. And a shape memory alloy member which is deformed by an electric current applied from the outside to selectively raise or lower the fixing member, and selectively fixes the friction member, thereby providing a two-stage friction damper using the shape memory alloy. Therefore, both the damping force required for low frequency vibration and the damping force required for high frequency vibration can be satisfied.

Description

Two stage friction damper using shape memory alloy {2 STAGE FRICTION DAMPER USING SHAPE MEMORY ALLOY}

The present invention relates to a friction damper using a shape memory alloy, and more particularly, a two-stage friction damper using a shape memory alloy capable of satisfying both the damping force required for low frequency vibration and the damping force required for high frequency vibration. It is about.

The friction damper has the function of absorbing or eliminating oscillation of the mechanical element caused, for example, by imbalance.

1 is a cross-sectional view of a friction damper according to the prior art. As shown, the friction damper according to the prior art includes a cylinder 6 and a piston rod 7 in which a predetermined portion is inserted into the cylinder 6. It is composed of In addition, a fixture (61) for connecting the cylinder (6) to one side of the vibration generating medium, a fixture (71) for connecting the piston rod (7) to the other side of the vibration generating medium, and one end of the piston rod (7). A friction member 9 which is formed in the inner surface of the cylinder 6 to perform a frictional action, and an air vent 72 formed inside the piston rod 7 to prevent the air inside the cylinder 6 from being compressed; It consists of.

The operation of the friction damper 8 will be described with reference to the configuration of the friction damper 8 according to the prior art.

When a certain amount of vibration is generated in the friction generating medium of the mechanical device, a relatively different positional displacement occurs between the inner circumferential surface of the cylinder 6 and the outer circumferential surface of the piston rod 7. The vibration amount is changed into frictional heat and attenuated by the friction member 9 formed between the cylinder 6 and the piston rod 7.

In addition, the vent 72 is a passage through which air escapes to the outside in order to prevent the air inside the cylinder 6 from being compressed to weaken the damping force when the piston rod 7 is moved to the left with reference to the drawings. To form.

On the other hand, in the vibration generating medium, a case in which a large amount of vibration is generated and a case in which a small amount of vibration is generated may be divided and both cases may be generated.

However, the same damping force is always generated by the conventional friction damper 8 as described in the drawing. Therefore, in the case where a small vibration displacement is generated (high frequency region), the friction damper 8 acts as a rigid body, which not only can quickly damp the vibration amount but also the noise is large.

On the other hand, when a large vibration displacement occurs (resonant region), the vibration amount cannot be attenuated quickly by the vibration amount exceeding the displacement limit of the damper 8, and the damper 8 may be damaged.

Thus, friction dampers require high damping coefficients (damping forces) in large vibration displacements (resonance regions) and low damping coefficients (damping forces) in small vibration displacements (high frequency regions), while conventional friction dampers always provide constant friction. Since only a constant attenuation coefficient can be obtained with an area, there is a problem that an appropriate attenuation coefficient cannot be obtained that can satisfy both vibrations generated in the resonance region and the high frequency region.

In addition, the conventional fluid damper has a problem in that an elastic effect due to the restoring force of the air chamber is generated by providing an air chamber for volume compensation for displacement, a damper that can reduce such elastic effect is required.

The present invention has been invented to solve the above problems, and can satisfy both the damping force required for low frequency vibration and the damping force required for high frequency vibration, and shape memory capable of damping the elastic effect due to the restoring force. It is an object of the present invention to provide a two-stage friction damper using an alloy.

In other words, the present invention provides a shape memory alloy which can operate as a damper to damp vibration when a large vibration of a low frequency is applied, and secure a dustproof performance by lowering the damping force when a small vibration of a high frequency is applied. The purpose is to provide a two-stage friction damper used.

According to an aspect of the present invention for achieving the above object, a cylinder having a predetermined space therein; A piston rod moving longitudinally in the cylinder; A friction member friction with an outer circumferential surface of the piston rod to generate a damping force; A friction member receiver formed in the cylinder to accommodate the friction member; A fixing member which is lifted up and down in a direction perpendicular to the piston rod to fix the friction member inside the friction member accommodating part; And a shape memory alloy member which is deformed by a current applied from the outside to selectively lift or lower the fixing member, and selectively fixes the friction member. .

In the above-described configuration, a separate fixing member receiving portion is formed in the friction member receiving portion, one end of the shape memory alloy member is fixed inside the fixing member receiving portion, and the other end of the shape memory alloy member is attached to the fixing member. It may be fixed.

In the above configuration, when the friction member is located in the region of the friction member receiving portion, the fixing member is lifted from the fixing member receiving portion and moved to a position contacting the bottom surface of the friction member to limit the moving width of the friction member. can do.

In the two-stage friction damper using the shape memory alloy according to the present invention, when no current is applied to the shape memory alloy, a low damping force that can cope with a high frequency vibration is generated by the free streak section of the friction member, and the shape memory When the current is applied to the alloy, the friction member is fixed according to the increase in the rigidity of the shape memory alloy member, so that the damping force can be lowered as a high damping force is generated that can cope with low frequency vibration, thereby improving the dustproof performance.

1 is a cross-sectional view schematically showing a conventional direct acting piston type friction damper,
2 is a cross-sectional view showing a free stroke state of a two-stage friction damper using a shape memory alloy according to an embodiment of the present invention; and
3 is a cross-sectional view showing a state in which a fixing member of a two-stage friction damper using a shape memory alloy according to an embodiment of the present invention fixes the friction member.

Hereinafter, a preferred embodiment of a friction damper using a shape memory alloy according to the present invention will be described in detail with reference to the accompanying drawings. For reference, in the following description of the present invention, terms referring to the components of the present invention are named in consideration of the function of each component, and should not be understood as a meaning of limiting the technical components of the present invention. Will be.

2 is a cross-sectional view showing a free stroke state of a two-stage friction damper using a shape memory alloy according to an embodiment of the present invention, and FIG. 3 is a two-stage friction damper using a shape memory alloy according to an embodiment of the present invention. 2 and 3, the friction damper of the present invention includes a cylinder 110, a piston rod 120, a friction member 130, and a friction member accommodation unit 160. ), A fixing member 150, and a shape memory alloy 150.

The cylinder 110 is a cylindrical body, and has a predetermined space in which the piston rod 120 can be moved in the longitudinal direction.

The piston rod 120 penetrates one end of the cylinder 110 in a longitudinal direction and is connected to a vibration generating medium (not shown) located outside of the cylinder 110, and generates vibration according to the reciprocating movement inside the cylinder 110. Dampens the vibration of the medium.

The friction member 130 is rubbed with the outer circumferential surface of the piston rod 120 to provide a damping force for damping the vibration of the external vibration generating medium. The friction member 130 may be attached to a polyurethane material such as a sponge or a synthetic fiber material of various forms having a certain durability and wear resistance.

The friction member accommodating part 160 is a space having a length L _{1 such} that the friction member 130 is accommodated and moved in the movement direction of the piston rod 120, and is formed at one side of the cylinder 110. . That is, the friction member accommodating part 160 is formed integrally with the cylinder 110 and has a larger diameter than other parts of the cylinder 110.

Preferably, the friction member accommodating part 160 is formed to surround the outer circumferential surface of the piston rod 120. In addition, the friction member 130 has a size that can be moved in the vertical direction as the piston rod 120 moves around the outer circumferential surface of the piston rod 120 within the friction member accommodating part 160. Therefore, the friction member 130 moves along the piston rod 120 in contact with the piston rod 120 when the piston rod 120 moves.

Meanwhile, the fixing member accommodating part 170 is formed adjacent to the friction member accommodating part 160. The fixing member accommodating part 170 is formed integrally with the cylinder 110 and is formed to have a larger diameter than the friction member accommodating part 160.

The fixing member accommodating part 170 is mounted to the fixing member 150, which can be moved up and down in the vertical direction from the fixing member accommodating part 170 by the shape memory alloy member 140. have. That is, the shape memory alloy member 140 is a coil spring-shaped metal connected to both ends of the fixing member 150 inside the fixing member accommodating portion 170. Specifically, the shape memory alloy member 140 is stretched and contracted in a direction perpendicular to the longitudinal direction of the piston rod 120. Therefore, the fixing member 150 can be raised and lowered perpendicularly to the longitudinal direction of the piston rod 120.

In addition, when the shape memory alloy member 140 is deformed through a heat generated by an electric current applied from the outside to form a tensioned state (that is, a lifted state of the fixing member), the fixing member 150 is frictional as shown in FIG. 3. Positioning within the bottom surface 131 of the member 130 limits the moving length (L ₂ ) of the friction member 130. At this time, the fixing member 150 may be formed of an elastic material to increase the damping force by providing a high damper force.

That is, as shown in FIG. 3, when the shape memory alloy member 140 is tensioned according to the application of the current of the shape memory alloy member 140, the fixing member 150 may move the friction member 130 by a predetermined width (moving length; L). ₂ ) the fixing member 150 may provide a high damper force.

Here, the shape memory alloy member 140 is installed in the friction damper according to the present invention after the following process. First, the shape memory alloy member 140 is subjected to shape memory heat treatment, and the shape memory alloy member 140 subjected to the shape memory heat treatment is easily deformed by an external force at a transformation temperature or less, so that an external force is applied so that its length becomes the initial set length. do. Thereafter, the shape memory alloy member 140 which is deformed to be reduced in the vertical direction is inserted between the friction member 130 and the fixing member accommodating portion 170.

When current is applied to the shape memory alloy member 140 thus installed, heat is generated. When the generated heat is raised to the shape recovery start temperature, the shape memory alloy member 140 is deformed and its length is increased.

Therefore, as shown in FIG. 3, the fixing member 150 moves to a position where the bottom surface 131 of the friction member 130 is supported in accordance with the tension of the shape memory alloy member 140 (supported by the fixing member receiving portion). being). In this state, when the piston rod 120 is reciprocated, the friction member 130 maintains the state fixed to the fixing member 150, so that a large damping force is generated.

On the other hand, when the current applied as shown in FIG. 2 is removed, the shape memory alloy member 140 returns to its original rigidity, whereby the shape memory alloy member 140 operates as an elastic body, and the friction member 130 is a piston. As the rod 120 moves, the friction member accommodating part 160 becomes movable.

In the present invention, the deformation of the shape memory alloy member 140 is increased in the manner in which the current is applied. However, when the current is applied to the shape memory alloy member according to the shape of the external force applied after the shape memory heat treatment, the rigidity This can be modified in a reduced manner.

The operation of the friction damper using the shape memory alloy according to the present invention will be described below.

First, when the vibration from the external vibration generating medium is small, that is, in the high frequency section, a low damping force is required. In this case, no current is applied to the shape memory alloy member 140 (as shown in FIG. 2).

In this state, when a small vibration from the vibration generating medium is generated and the piston rod 120 moves, the friction member 130 is fixed at the friction member accommodating part 160 according to the movement of the piston rod 120. The length L ₁ up to 170 can be moved.

As a result, the friction member 130 has a wide free-stroke section, and a small amount of damping force is generated.

On the other hand, when the vibration is large from the external vibration generating medium, that is, a large damping force is required in the low frequency section. In this case, a current is applied to the shape memory alloy member 140.

Therefore, the shape memory alloy member 140 is tensioned and the fixed member 150 is lifted. Accordingly, the fixing member 150 is in a state of supporting the bottom surface 131 of the friction member 130, so that the friction member 130 is in a fixed state. In this state, when a large vibration is generated from the vibration generating medium and the piston rod 120 moves, as shown in FIG. 3, the movement of the friction member 130 is limited even when the piston rod 120 moves.

As a result, the moving length L ₂ of the friction member 130 in the piston rod 120 is shortened, whereby a large magnitude of damping force can be generated.

As described above, the friction damper according to the present invention has a two-stage stroke section, and when a small damping force is required, no current is applied to the shape memory alloy member 140, so that the friction member 130 Has a free stroke section, when the damping force has a small magnitude and a large damping force is required, a current is applied to the shape memory alloy member 140 so that the friction member 130 cannot be moved. Will have

The embodiments of the present invention described above are merely illustrative of the technical idea of the present invention, and the protection scope of the present invention should be interpreted by the following claims. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. It should be interpreted that it is included in the scope of right.

110: cylinder 120: piston rod
130: friction member 140: shape memory alloy member
150: fixing member 160: friction member receiving portion
170: holding member receiving portion

Claims (3)

A cylinder 110 having a predetermined space therein;
A piston rod 120 moving in the longitudinal direction in the cylinder 110;
A friction member 130 which friction with the outer circumferential surface of the piston rod 120 to generate a damping force;
A friction member accommodating part 160 formed in the cylinder 110 to accommodate the friction member 130;
A fixing member 150 which is lowered in a vertical direction to the piston rod 120 to fix the friction member 130 in the friction member accommodating part 160; And
The shape memory alloy includes a shape memory alloy member 140 that selectively deforms and lowers the fixing member 150 by being deformed by a current applied from the outside, thereby selectively restricting the moving length of the friction member 130. Stage friction damper The method of claim 1,
The friction member accommodating part 160 is provided with a fixing member accommodating part 170 having a diameter larger than that of the friction member accommodating part 160.
One end of the shape memory alloy member 140 is fixed to the inside of the fixing member receiving portion 170, the other end of the shape memory alloy member 140 is fixed to the fixing member 150 Two stage friction damper using memory alloy. The method of claim 2,
The fixing member 150 is lifted from the fixing member accommodating part 170 when the friction member 130 is located in the region of the friction member accommodating part 160 to be in contact with the bottom surface of the friction member 130. Two-stage friction damper using a shape memory alloy, characterized in that moved to limit the movement width of the friction member (130).

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