JP2020020461A - Eddy current damper - Google Patents

Abstract

To provide an eddy current damper in which local temperature rise of a conductive member can be suppressed.SOLUTION: An eddy current damper 1 is provided in which damping force is obtained by relatively rotating permanent magnets 6 and a conductive member 4 by using a screw shaft 2 and a ball nut 3. The eddy current damper 1 includes a cylindrical magnet holding member 5, the plurality of permanent magnets 6, and the cylindrical conductive member 4. The plurality of permanent magnets 6 are fixed to the magnet holding member 5, and magnetic poles of the permanent magnets 6 are arranged in an alternately inverted manner in a circumferential direction of the magnet holding member 5. The conductive member 4 is opposed to the plurality of permanent magnets 6 at an interval, and relatively rotatable with respect to the plurality of permanent magnets 6. Axial displacement of the screw shaft 2 relatively moves the plurality of permanent magnets 6 and the conductive member 4 in an axial direction of the screw shaft 2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an eddy current damper.

  2. Description of the Related Art In order to protect a building from vibrations caused by an earthquake or the like, a vibration damping device is attached to the building. The vibration damping device attenuates vibration by converting kinetic energy given to the building into other energy such as heat energy. An oil damper is known as such a vibration damping device. The oil damper attenuates vibration by using the resistance of a viscous fluid filled in a cylinder.

  However, since the viscosity of the viscous fluid depends on the temperature of the viscous fluid, the damping force of the oil damper depends on the temperature of the viscous fluid. Therefore, when using an oil damper for a building, it is necessary to select an appropriate viscous fluid in consideration of the use environment. An eddy current damper is known as a damper whose damping force does not depend on temperature.

  An eddy current damper is disclosed, for example, in Japanese Patent Publication No. 5-86496 (Patent Document 1).

  The eddy current damper of Patent Document 1 includes a plurality of permanent magnets attached to a main cylinder, a hysteresis material connected to a screw shaft, a ball nut meshing with the screw shaft, and a sub-cylinder connected to the ball nut. Is provided. The plurality of permanent magnets differ in the arrangement of magnetic poles alternately. The hysteresis material faces the plurality of permanent magnets and is relatively rotatable. When kinetic energy is applied to the eddy current damper, the sub-cylinder and the ball nut reciprocate in the axial direction, and the hysteresis member rotates by the action of the ball screw. This causes a hysteresis loss and consumes kinetic energy. Patent Literature 1 discloses that eddy current is generated in the hysteresis material, and kinetic energy is consumed (damping force is obtained) due to eddy current loss.

Japanese Patent Publication No. 5-86496

  However, in the eddy current damper of Patent Document 1, an eddy current is generated near the surface of the hysteresis material (conductive member) on the side facing the permanent magnet, so that this region is intensively heated and locally heated to a high temperature. I do. If the temperature of the conductive member is locally increased, the strength of the conductive member itself and its peripheral components may be adversely affected. In addition, when the heat of the locally heated conductive member is transmitted to the permanent magnet, the permanent magnet is demagnetized, and the damping force of the eddy current damper may be reduced.

  An object of the present invention is to provide an eddy current damper capable of suppressing a local temperature rise of a conductive member.

  The eddy current damper of the present invention obtains a damping force by relatively rotating the permanent magnet and the conductive member using the screw shaft and the ball nut. The eddy current damper includes a cylindrical magnet holding member, a plurality of permanent magnets, and a cylindrical conductive member. The plurality of permanent magnets are fixed to a magnet holding member, and are arranged by alternately reversing the arrangement of magnetic poles in a circumferential direction of the magnet holding member. The conductive member faces the plurality of permanent magnets with a gap therebetween, and is rotatable relative to the plurality of permanent magnets. The screw shaft is displaced in the axial direction to relatively move the plurality of permanent magnets and the conductive member in the axial direction of the screw shaft.

  According to the eddy current damper of the present invention, a local temperature rise of the conductive member can be suppressed.

FIG. 1 is a cross-sectional view of the eddy current damper of the first embodiment in a plane along the axial direction. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is a sectional view taken along line III-III in FIG. FIG. 4 is a partially enlarged view of FIG. FIG. 5 is a cross-sectional view of the eddy current damper of the first embodiment when the screw shaft is at a stroke end position. FIG. 6 is a cross-sectional view of the eddy current damper of the second embodiment taken along a plane along the axial direction. FIG. 7 is a perspective view of a conductive member of the eddy current damper of the second embodiment. FIG. 8 is a cross-sectional view of the eddy current damper of the second embodiment when the screw shaft is at a stroke end position. FIG. 9 is a cross-sectional view of the eddy current damper of the third embodiment in a plane along the axial direction. FIG. 10 is a cross-sectional view of the eddy current damper of the fourth embodiment taken along a plane along the axial direction.

  (1) The eddy current damper of the present embodiment obtains a damping force by relatively rotating a permanent magnet and a conductive member using a screw shaft and a ball nut. The eddy current damper includes a cylindrical magnet holding member, a plurality of permanent magnets, and a cylindrical conductive member. The plurality of permanent magnets are fixed to a magnet holding member, and are arranged by alternately reversing the arrangement of magnetic poles in a circumferential direction of the magnet holding member. The conductive member faces the plurality of permanent magnets with a gap therebetween, and is rotatable relative to the plurality of permanent magnets. The screw shaft is displaced in the axial direction to relatively move the plurality of permanent magnets and the conductive member in the axial direction of the screw shaft.

  When vibration is applied to the eddy current damper of (1), the screw shaft reciprocates in the axial direction. When the permanent magnet and the conductive member facing the permanent magnet are relatively moved in the axial direction using the reciprocating motion of the screw shaft, the region of the conductive member facing the permanent magnet also moves in the axial direction. This prevents eddy currents from being concentrated on a specific location of the conductive member and prevents the conductive member from being locally heated.

  (2) In the eddy current damper of (1), the magnet holding member is fixed to the screw shaft, the conductive member is fixed to the ball nut, and the inner peripheral surface of the conductive member faces a plurality of permanent magnets. Is preferred.

  In such an eddy current damper of (2), the permanent magnet and the conductive member relatively move in the axial direction as the magnet holding member reciprocates with the screw shaft. Further, the permanent magnet is provided inside the conductive member, and the rotation of the conductive member causes the permanent magnet and the conductive member to relatively rotate. Since the conductive member that generates heat rotates, the conductive member is air-cooled, and the temperature rise of the conductive member is further suppressed.

  (3) In the eddy current damper of (2), the conductive member preferably includes a plurality of through holes in a region other than a region capable of facing the plurality of permanent magnets.

  In such an eddy current damper of (3), the through-hole is not provided in the region of the conductive member facing the permanent magnet (the region where the eddy current is generated), so that the damping force of the eddy current damper is maintained. It is. On the other hand, since the through hole is provided in a region of the conductive member that does not face the permanent magnet, the inside and outside of the conductive member can be ventilated. By ventilating the inside and outside of the conductive member, a rise in the temperature of the conductive member is further suppressed.

  (4) In the eddy current damper of (1), the magnet holding member is fixed to the ball nut, the conductive member is fixed to the screw shaft, and the outer peripheral surface of the conductive member faces a plurality of permanent magnets. Is preferred.

  In such an eddy current damper of (4), the permanent magnet and the conductive member relatively move in the axial direction as the conductive member reciprocates with the screw shaft. In addition, the conductive member is provided inside the magnet holding member, and the permanent magnet and the conductive member rotate relatively as the magnet holding member (permanent magnet) rotates.

  (5) In the eddy current damper of (4), it is preferable that the magnet holding member includes a plurality of through holes in a region other than a region where the plurality of permanent magnets are fixed.

  In the eddy current damper of (5), the through hole is provided in the magnet holding member, so that the inside and the outside of the magnet holding member can be ventilated. By ventilating the inside and outside of the magnet holding member, the temperature rise of the conductive member provided inside the magnet holding member is further suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts have the same reference characters allotted, and description thereof will not be repeated.

[First Embodiment]
FIG. 1 is a cross-sectional view of the eddy current damper of the first embodiment in a plane along the axial direction. The eddy current damper 1 includes a magnet holding member 5, a plurality of permanent magnets 6, and a conductive member 4. The eddy current damper 1 obtains a damping force by relatively rotating the permanent magnet 6 and the conductive member 4 using the screw shaft 2 and the ball nut 3. In this specification, “axial direction” means the axial direction of the screw shaft 2.

[Screw shaft]
The screw shaft 2 is a member extending linearly, and is fixed to a fixture 21 attached to a building. When the building shakes, the vibration is transmitted to the screw shaft 2 via the fixture 21, the screw shaft 2 is displaced in the axial direction, and reciprocates (stroke) in synchronization with the vibration. FIG. 1 shows a state where the screw shaft 2 is located at the center of the stroke. The stroke center position means the center of the reciprocating movement range along the axial direction of the screw shaft 2. The eddy current damper 1 is attached to a building with the screw shaft 2 at the center of the stroke. A screw portion is formed on the outer peripheral surface of the screw shaft 2.

[Ball nut]
The ball nut 3 forms the screw shaft 2 and a ball screw. The ball nut 3 includes a through hole and a flange. The screw shaft 2 is passed through the through hole, and a screw portion that meshes with the screw portion of the screw shaft 2 is formed on the inner peripheral surface of the through hole. Therefore, when the screw shaft 2 is displaced in the axial direction, the ball nut 3 rotates. That is, the ball nut 3 converts the translational movement of the screw shaft 2 into a rotational movement. The flange portion has a hollow disk shape when viewed from the axial direction.

[Magnet holding member]
FIG. 2 is a partially enlarged view of FIG. The magnet holding member 5 has a cylindrical shape including an inner peripheral surface and an outer peripheral surface. The inner peripheral surface of the magnet holding member 5 is fixed to the screw shaft 2. Therefore, when the screw shaft 2 strokes in the axial direction, the magnet holding member 5 also strokes. The method for fixing the magnet holding member 5 to the screw shaft 2 may be welding or mounting via a mounting member, and is not particularly limited.

  The magnet holding member 5 holds a plurality of permanent magnets 6. The material of the magnet holding member 5 is preferably a magnetic material such as carbon steel or cast iron. In this case, the magnet holding member 5 functions as a yoke, and suppresses the leakage of the magnetic flux from the permanent magnet 6 to the outside.

[permanent magnet]
FIG. 3 is a sectional view taken along line III-III in FIG. The plurality of permanent magnets 6 are fixed to the outer peripheral surface of the magnet holding member 5. The plurality of permanent magnets 6 are arranged in the circumferential direction of the magnet holding member 5, and a gap is provided between two adjacent permanent magnets 6.

  FIG. 4 is a partially enlarged view of FIG. The plurality of permanent magnets 6 are arranged by alternately reversing the arrangement of magnetic poles in the circumferential direction of the magnet holding member 5. In other words, the permanent magnets 6 adjacent to each other in the circumferential direction of the magnet holding member 5 have their magnetic poles reversed from each other. Although FIG. 4 shows a case where the magnetic poles of the permanent magnet 6 are arranged in the radial direction of the magnet holding member 5, the arrangement of the magnetic poles is not limited to this, and the axial direction of the magnet holding member 5 (that is, the axis of the screw shaft). Direction).

[Conductive member]
Referring to FIG. 2, conductive member 4 has a cylindrical shape including an inner peripheral surface and an outer peripheral surface and extending in the axial direction. The axial length of the conductive member 4 is longer than the reciprocating distance of the permanent magnet 6 in the axial direction. A part of the ball nut 3, a part of the screw shaft 2, the magnet holding member 5, and the permanent magnet 6 are accommodated inside the conductive member 4 (inside space of the cylinder). By housing the ball nut 3 and the like inside the conductive member 4, the eddy current damper 1 can be reduced in size.

  One end of the conductive member 4 is fixed to a flange of the ball nut 3. Therefore, when the ball nut 3 rotates, the conductive member 4 also rotates accordingly. The other end of the conductive member 4 is fixed to a fixture 22 attached to a building via the thrust bearing 11. Therefore, even if the conductive member 4 rotates, the fixture 22 does not rotate. The other end of the conductive member 4 is supported by a support member 13 via a radial bearing 14.

  The inner peripheral surface of the conductive member 4 faces the plurality of permanent magnets 6 with a gap. “Opposing” means that when only the target member is projected in the radial direction of the magnet holding member 5, both overlap. The size of the gap is preferably as small as possible so that the magnetic flux from the permanent magnet 6 can efficiently reach the conductive member 4. Further, the distance between each permanent magnet 6 and the inner peripheral surface of the conductive member 4 is preferably constant.

  The material of the conductive member 4 is a material having conductivity, such as steel, for generating an eddy current by a magnetic field formed by the permanent magnet 6.

  In addition, the eddy current damper 1 may include a cover 12 for protecting the conductive member 4 and the like. The cover 12 has a cylindrical shape and accommodates a part of the conductive member 4, the ball nut 3 and the screw shaft 2 therein. One end of the cover 12 is fixed to the ball nut 3 via the thrust bearing 11 and the radial bearing 14. Further, the other end of the cover 12 is fixed to a fixture 22 fixed to the building.

  When vibration is applied to the eddy current damper 1 of the first embodiment having the above-described configuration and the conductive member 4 rotates, the magnetic flux passing through the inner peripheral surface of the conductive member 4 changes. An electric current is generated. When an eddy current is generated, a new magnetic flux (a demagnetizing field) is generated. This demagnetizing field hinders the rotation of the conductive member 4 (that is, hinders the rotation of the ball nut 3). When the rotation of the ball nut 3 is hindered, the axial movement of the screw shaft 2 is also hindered, and the vibration is attenuated. This becomes the damping force due to the eddy current.

  On the other hand, when an eddy current is generated in the conductive member 4, the temperature of the conductive member 4 increases due to Joule heat. If the position of the permanent magnet 6 in the axial direction does not move relative to the conductive member 4, the eddy current is intensively generated in a specific region of the conductive member 4 facing the permanent magnet 6. The region is likely to be locally hot. If the temperature of the conductive member 4 becomes locally high, there is a possibility that the strength and the like of the conductive member 4 itself and its peripheral components are adversely affected. In addition, since the heat of the conductive member 4 that has been locally heated is transmitted to the permanent magnet 6, the permanent magnet 6 may be demagnetized, and the damping force of the eddy current damper may be reduced.

  However, according to the eddy current damper 1 of the first embodiment, since the position of the permanent magnet 6 in the axial direction moves relatively to the conductive member 4, a local temperature rise of the conductive member 4 can be suppressed. . Hereinafter, this point will be described in detail.

[Suppression of local temperature rise of conductive member]
Referring to FIG. 2, when vibration is applied to eddy current damper 1 in a state where screw shaft 2 is at the stroke center position, screw shaft 2 moves from the stroke center position to the stroke end position. The stroke end position means an end of a reciprocating movement range of the screw shaft 2 in the axial direction.

  FIG. 5 is a cross-sectional view of the eddy current damper of the first embodiment when the screw shaft is at a stroke end position. If the screw shaft 2 (that is, the permanent magnet 6) moves in the axial direction, the conductive member 4 does not move in the axial direction, so that the region of the conductive member 4 facing the permanent magnet 6 also moves. That is, in the eddy current damper 1 according to the first embodiment, the eddy current does not always continue to be generated only in a specific region of the conductive member 4, but the eddy current generation region changes in the axial direction with the stroke of the screw shaft 2. Go to Therefore, compared to an eddy current damper in which the eddy current generation region does not move in the axial direction, the amount of heat generated by the eddy current can be dispersed over a wide range of the conductive member 4, and the temperature of the conductive member 4 locally increases. Is suppressed.

  Suppressing the local temperature rise of the conductive member 4 means that the maximum temperature of the conductive member 4 decreases. If the maximum temperature of the conductive member 4 is low, the influence of the radiant heat from the conductive member 4 is weakened, so that the temperature rise of the permanent magnet 6 due to the radiant heat is also suppressed.

  Moreover, in the eddy current damper 1 of the first embodiment, the conductive member 4 itself that generates heat rotates, so that the conductive member 4 can be directly air-cooled. Thereby, the temperature rise of the conductive member 4 can be further suppressed.

  The eddy current damper of the first embodiment has been described above. However, the eddy current damper of the present invention is not limited to this, and the following embodiments can be adopted.

[Second embodiment]
FIG. 6 is a cross-sectional view of the eddy current damper of the second embodiment taken along a plane along the axial direction. The eddy current damper 1 of the second embodiment differs from the first embodiment in that a through hole 7 is provided in the conductive member 4. In the following description, only differences from the first embodiment will be described, and description of the same configuration as the first embodiment will be omitted.

[Through hole]
FIG. 7 is a perspective view of a conductive member of the eddy current damper of the second embodiment. The conductive member 4 includes a first row of through holes 15 and a second row of through holes 16.

  The first through-hole row 15 includes a plurality of through-holes 7 arranged in the circumferential direction of the conductive member 4. The through hole 7 penetrates the conductive member 4 along the radial direction of the conductive member 4.

  Referring to FIG. 6, through hole 7 allows ventilation between the inside of conductive member 4 and the outside of conductive member 4. Therefore, by the stroke of the screw shaft 2, the air inside the conductive member 4 can be agitated, and the temperature rise of the conductive member 4 can be suppressed.

  Also, in the eddy current damper of the second embodiment, similarly to the first embodiment, the conductive member 4 that generates heat itself rotates, so that the conductive member 4 can be directly air-cooled. Thereby, the temperature rise of the conductive member 4 can be further suppressed.

  Referring to FIG. 7, the shape of through-hole 7 is a polygon, a circle, an ellipse, or the like, and the shape is not particularly limited.

  It is preferable that the through holes 7 are arranged at regular intervals along the circumferential direction of the conductive member 4. If the through holes 7 are arranged at equal intervals, the air inside the conductive member 4 is easily stirred uniformly. Therefore, the temperature rise of the conductive member 4 can be suppressed uniformly in the circumferential direction.

  FIG. 7 shows a case where the through holes 7 of the first through hole row 15 and the through holes 7 of the second through hole row 16 are provided in the same phase in the circumferential direction of the conductive member 4. The through-holes 7 in the row 15 and the through-holes 7 in the second through-hole row 16 do not have to be in phase.

  Subsequently, the arrangement of the first through-hole row 15 and the second through-hole row 16 will be described.

  FIG. 8 is a cross-sectional view of the eddy current damper of the second embodiment when the screw shaft is at a stroke end position. Since the region A of the conductive member 4 which can face the permanent magnet 6 is a region where an eddy current is generated, the conductive member 4 is desirably present in the entire axial direction and the circumferential direction of the conductive member. Therefore, in the eddy current damper 1 of the second embodiment, the through hole 7 is not provided in the region A where the conductive member can face the permanent magnet.

  On the other hand, the regions on both sides in the axial direction of the region A of the conductive member that can face the permanent magnet are outside the reciprocating range of the permanent magnet 6 and therefore cannot face the permanent magnet 6. Therefore, in this region, no eddy current is generated, or even if it is generated, the eddy current is weak and does not significantly affect the damping force of the eddy current damper. Therefore, in the eddy current damper of the second embodiment, the first through-hole row 15 and the second through-hole row 16 are provided in a region other than the region A of the conductive member that can face the permanent magnet.

  More specifically, regions other than the region A of the conductive member that can face the permanent magnet are provided on both axial sides of the region A of the conductive member that can face the permanent magnet. The first through-hole row 15 is provided on one of them, and the second through-hole row 16 is provided on the other.

[Magnet holding member]
The cylindrical magnet holding member 5 preferably includes two end faces 23. The two end surfaces 23 have a hollow flat disk shape when viewed from the axial direction, and extend along the radial direction of the magnet holding member 5 when viewed in a cross section perpendicular to the axial direction.

  According to such a configuration, when the magnet holding member 5 is displaced, the air inside the conductive member 4 is compressed by the end surface 23 of the magnet holding member 5 and is easily released from the through hole 7. For example, suppose that magnet holding member 5 is displaced to the left in FIG. 6 with reference to FIG. Then, the air inside the conductive member 4 in the traveling direction of the magnet holding member 5 is compressed and flows out from the through holes 7 of the first through hole row 15. On the other hand, air flows from the outside of the conductive member 4 to the inside of the conductive member 4 on the opposite side (right side) of the magnet holding member 5 through the through holes 7 of the second through hole row 16.

  Thereby, the inside and the outside of the conductive member 4 can be ventilated on both sides in the axial direction, and the temperature rise of not only one end of the conductive member 4 but also the other end in the axial direction can be suppressed. When the magnet holding member 5 is displaced to the right in FIG. 6, the above description is reversed.

  Next, an eddy current damper according to a third embodiment will be described.

[Third embodiment]
FIG. 9 is a cross-sectional view of the eddy current damper of the third embodiment in a plane along the axial direction. The eddy current damper 1 of the third embodiment differs from the first embodiment in that the magnet holding member 5 is arranged outside the conductive member 4 and rotates. In the following description, only differences from the first embodiment will be described, and description of the same configuration as the first embodiment will be omitted.

[Magnet holding member]
The magnet holding member 5 has a cylindrical shape including an inner peripheral surface and an outer peripheral surface and extending in the axial direction. A part of the ball nut 3, a part of the screw shaft 2, the conductive member 4, and the permanent magnet 6 are accommodated inside the magnet holding member 5 (inside space of the cylinder). By accommodating the ball nut 3 and the like inside the magnet holding member 5, the eddy current damper can be reduced in size.

  One end of the magnet holding member 5 is fixed to the flange of the ball nut 3. Therefore, when the ball nut 3 rotates, the magnet holding member 5 also rotates accordingly. The other end of the magnet holding member 5 is fixed to a fixture 22 attached to the building via the thrust bearing 11. Therefore, even if the magnet holding member 5 rotates, the fixture 22 does not rotate.

[permanent magnet]
The plurality of permanent magnets 6 are fixed to the inner peripheral surface of the magnet holding member 5.

[Conductive member]
The conductive member 4 has a cylindrical shape including an inner peripheral surface and an outer peripheral surface. The inner peripheral surface of the conductive member 4 is fixed to the screw shaft 2. Therefore, when the screw shaft 2 strokes in the axial direction, the conductive member 4 also strokes. The outer peripheral surface of the conductive member 4 faces the plurality of permanent magnets 6 with a gap.

  When vibration is applied to the eddy current damper of the third embodiment having such a configuration, the conductive member 4 strokes in the axial direction. That is, the conductive member 4 and the permanent magnet 6 move relatively in the axial direction. Therefore, similarly to the first embodiment, the amount of heat generated by the eddy current can be dispersed over a wide range of the conductive member 4, and the temperature of the conductive member 4 is locally prevented from rising.

[Fourth embodiment]
FIG. 10 is a cross-sectional view of the eddy current damper of the fourth embodiment taken along a plane along the axial direction. The eddy current damper 1 of the fourth embodiment differs from the third embodiment in that a through hole 7 is provided in the magnet holding member 5. In the following description, only differences from the third embodiment will be described, and description of the same configuration as the third embodiment will be omitted.

  The eddy current damper of the fourth embodiment has a configuration in which the conductive member 4 and the magnet holding member 5 of the eddy current damper of the second embodiment in which the through-hole 7 is provided in the conductive member 4 are interchanged. Therefore, the magnet holding member of the eddy current damper of the fourth embodiment will be described below, but the shape is the same as the conductive member of the eddy current damper of the second embodiment shown in FIG.

[Magnet holding member]
Referring to FIG. 10, magnet holding member 5 includes a first row of through holes 15 and a second row of through holes 16.

  The through hole 7 penetrates the magnet holding member 5 along the radial direction of the magnet holding member 5. The through hole 7 allows the inside of the magnet holding member 5 and the outside of the magnet holding member 5 to ventilate. Therefore, by the stroke of the screw shaft 2, the air inside the magnet holding member 5 can be agitated, and the temperature rise of the conductive member 4 can be suppressed.

  In the eddy current damper of the fourth embodiment, the through hole 7 is not provided in the area B of the magnet holding member where the permanent magnet is provided. The first through-hole row 15 and the second through-hole row 16 are provided in an area other than the area where the permanent magnet of the magnet holding member is provided.

  More specifically, areas other than the area B where the permanent magnet of the magnet holding member is provided are provided on both sides in the axial direction of the area B where the permanent magnet of the magnet holding member is provided. The first through-hole row 15 is provided on one of them, and the second through-hole row 16 is provided on the other.

  Thereby, the inside and the outside of the magnet holding member 5 can be ventilated on both sides in the axial direction, and the temperature rise is suppressed not only at one end of the conductive member 4 but also at the other end in the axial direction.

  The eddy current damper of the present embodiment has been described above. In addition, it is needless to say that the present invention is not limited to the above embodiment, and various changes can be made without departing from the spirit of the present invention.

  INDUSTRIAL APPLICABILITY The eddy current damper of the present invention is useful for a vibration damping device and a seismic isolation device for a building.

1: eddy current damper 2: screw shaft 3: ball nut 4: conductive member 5: magnet holding member 6: permanent magnet 7: through hole 11: thrust bearing 12: cover 13: support member 14: radial bearing 15: first Through-hole row 16: Second through-hole row 21: Fixture 22: Fixture 23: End face of magnet holding member A: Area opposed to permanent magnet of conductive member B: Area where permanent magnet of magnet holding member is provided

Claims (5)

An eddy current damper that obtains a damping force by relatively rotating a permanent magnet and a conductive member using a screw shaft and a ball nut,
A cylindrical magnet holding member,
A plurality of permanent magnets fixed to the magnet holding member and arranged by alternately reversing the arrangement of magnetic poles in the circumferential direction of the magnet holding member,
A cylindrical conductive member that is opposed to the plurality of permanent magnets with a gap therebetween and is rotatable relative to the plurality of permanent magnets,
An eddy current damper, wherein the screw shaft is displaced in the axial direction to relatively move the plurality of permanent magnets and the conductive member in the axial direction of the screw shaft. The eddy current damper according to claim 1,
The magnet holding member is fixed to the screw shaft,
The conductive member is fixed to the ball nut,
An eddy current damper, wherein an inner peripheral surface of the conductive member faces the plurality of permanent magnets. The eddy current damper according to claim 2,
The eddy current damper, wherein the conductive member includes a plurality of through holes in a region other than a region capable of facing the plurality of permanent magnets. The eddy current damper according to claim 1,
The magnet holding member is fixed to the ball nut,
The conductive member is fixed to the screw shaft,
An eddy current damper, wherein an outer peripheral surface of the conductive member faces the plurality of permanent magnets. The eddy current damper according to claim 4, wherein
The eddy current damper, wherein the magnet holding member includes a plurality of through holes in a region other than a region where the plurality of permanent magnets are fixed.

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