JP2019100438A - Eddy current damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an eddy current type damper capable of suppressing an excessive temperature rise of a conductive member and a permanent magnet. An eddy current type damper 1 includes a conductive member 8, a magnet holding member 4, a first permanent magnet 6, a second permanent magnet 7, a screw shaft 2, and a ball nut 3. The cylindrical conductive member 8 has conductivity. The cylindrical magnet holding member 4 includes a surface 5 facing the conductive member 8 with a gap and a recess 9 provided on the surface 5. The first permanent magnet 6 is fixed to the recess 9 and faces the conductive member 8 with a gap. The second permanent magnet 7 is fixed to the concave portion 9, faces the conductive member 8 with a gap, is adjacent to the first permanent magnet 6 in the circumferential direction of the magnet holding member 4, and has the magnetic poles of the first permanent magnet 6. The arrangement is reversed. The ball nut 3 is fixed to the magnet holding member 4 or the conductive member 8 and meshes with the screw shaft 2. The thermal conductivity of the magnet holding member 4 is higher than the thermal conductivity of the first permanent magnet 6 and the thermal conductivity of the second permanent magnet 7. [Selection diagram] Fig. 2

Description

  The present invention relates to an eddy current damper.

  In order to protect the building from vibrations due to earthquakes, etc., a damping system is attached to the building. The vibration control device converts kinetic energy given to the building into other energy such as thermal energy. This suppresses large shaking of the building. The vibration control device is, for example, a damper. The types of dampers are, for example, oil type and shear resistance type. In general, oil type and shear resistance type dampers are often used in buildings. The oil type damper uses the incompressible fluid in the cylinder to damp the vibration. The shear resistance damper damps the vibration by using the shear resistance of the viscous fluid.

  However, the viscosity of the viscous fluid used in particular in shear resistant dampers depends on the temperature of the viscous fluid. That is, the damping force of the shear resistance damper depends on the temperature of the viscous fluid. Therefore, when using a shear resistant damper in a building, it is necessary to select an appropriate viscous fluid in consideration of the use environment. Further, in a damper using a fluid such as an oil type or a shear resistance type, the pressure of the fluid may rise due to temperature rise and the like, and mechanical elements such as the seal material of the cylinder may be damaged. As a damper whose damping force does not depend on temperature, there is an eddy current damper.

  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 member connected to a screw shaft, a ball nut meshing with the screw shaft, and a sub cylinder connected to a ball nut. Equipped with The plurality of permanent magnets alternate in the arrangement of the magnetic poles. The hysteresis material faces the plurality of permanent magnets and is capable of relative rotation. When kinetic energy is applied to the eddy current damper, the sub cylinder and the ball nut move in the axial direction, and the hysteresis material is rotated by the action of the ball screw. Thereby, kinetic energy is consumed by the hysteresis loss. Further, it is described in Patent Document 1 that kinetic energy is consumed by an eddy current loss because an eddy current is generated in the hysteresis material.

Japanese Examined Patent Publication 5-86496

  In the eddy current type damper, heat is generated intensively in a member (conductive member) where the eddy current is generated. Therefore, if aftershocks occur many times in a short time or one earthquake lasts for a long time, the conductive member becomes hot. A conductive member is provided in the vicinity of the permanent magnet to generate an eddy current. When the conductive member becomes high temperature, radiant heat also makes the permanent magnet high temperature. When the permanent magnet becomes high temperature, the permanent magnet demagnetizes and the generated eddy current weakens. This reduces the damping force of the eddy current damper. Therefore, it is desirable that the eddy current damper include a cooling mechanism.

  However, Patent Document 1 does not disclose the cooling mechanism of the eddy current damper at all.

  An object of the present invention is to provide an eddy current damper that can suppress excessive temperature rise of a conductive member and a permanent magnet.

  The eddy current damper of the present embodiment includes a conductive member, a magnet holding member, a first permanent magnet, a second permanent magnet, a screw shaft, and a ball nut. The cylindrical conductive member has conductivity. The cylindrical magnet holding member includes a surface facing the conductive member with a gap and a recess provided on the surface. The first permanent magnet is fixed to the recess and faces the conductive member with a gap. The second permanent magnet is fixed to the recess, faces the conductive member with a gap, is adjacent to the first permanent magnet in the circumferential direction of the magnet holding member, and the arrangement of the first permanent magnet and the magnetic pole is reversed. The ball nut is fixed to the magnet holding member or the conductive member and engages with the screw shaft. The thermal conductivity of the magnet holding member is higher than the thermal conductivity of the first permanent magnet and the thermal conductivity of the second permanent magnet.

  According to the eddy current damper of the present embodiment, it is possible to suppress an excessive temperature rise of the conductive member and the permanent magnet.

FIG. 1 is an axial sectional view of the eddy current damper. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is a perspective view showing the recess. FIG. 4 is a cross-sectional view perpendicular to the axial direction of the eddy current damper. FIG. 5 is a partially enlarged view of FIG. FIG. 6 is a schematic view showing a magnetic circuit of the eddy current damper. FIG. 7 is a perspective view showing a first permanent magnet and a second permanent magnet in which the arrangement of magnetic poles is in the circumferential direction. FIG. 8 is a schematic view showing a magnetic circuit of the eddy current damper of FIG. FIG. 9 is a perspective view showing a plurality of first permanent magnets and a plurality of second permanent magnets arranged in the axial direction. FIG. 10 is a cross-sectional view in a plane along the axial direction of the eddy current damper of the second embodiment. FIG. 11 is a cross-sectional view in a plane perpendicular to the axial direction of the eddy current damper of the second embodiment. FIG. 12 is a cross-sectional view of a surface of the eddy current damper of the third embodiment along the axial direction. FIG. 13 is a partially enlarged view of FIG. FIG. 14 is a cross-sectional view of a surface of the eddy current damper of the fourth embodiment along the axial direction. FIG. 15 is a cross-sectional view of an eddy current damper including fins. FIG. 16 is a cross sectional view showing another embodiment of the fin. FIG. 17 is a cross-sectional view showing another embodiment of the fin.

  (1) The eddy current damper of the present embodiment includes a conductive member, a magnet holding member, a first permanent magnet, a second permanent magnet, a screw shaft, and a ball nut. The cylindrical conductive member has conductivity. The cylindrical magnet holding member includes a surface facing the conductive member with a gap and a recess provided on the surface. The first permanent magnet is fixed to the recess and faces the conductive member with a gap. The second permanent magnet is fixed to the recess, faces the conductive member with a gap, is adjacent to the first permanent magnet in the circumferential direction of the magnet holding member, and the arrangement of the first permanent magnet and the magnetic pole is reversed. The ball nut is fixed to the magnet holding member or the conductive member and engages with the screw shaft. The thermal conductivity of the magnet holding member is higher than the thermal conductivity of the first permanent magnet and the thermal conductivity of the second permanent magnet.

  The screw shaft and the ball nut constitute a ball screw. Vibration is applied to the eddy current damper, and when the screw shaft translates, the ball nut engaged with the screw shaft rotates. The magnet holding member or the conductive member is fixed to the ball nut. Therefore, when the ball nut rotates, the magnet holding member or the conductive member also rotates. The first permanent magnet and the second permanent magnet are fixed to the magnet holding member. Thus, when the magnet holding member or the conductive member rotates, an eddy current is generated in the conductive member, and a damping force is obtained. On the other hand, the conductive member generates heat due to the eddy current. Here, the first permanent magnet and the second permanent magnet are fixed to the recess provided on the surface (the outer peripheral surface or the inner peripheral surface) facing the conductive member of the magnet holding member. Therefore, with respect to the distance between the conductive member and the surface of the magnet holding member and the distance between the conductive member and the first permanent magnet and the second permanent magnet, the permanent magnet is fixed to the surface of the conventional magnet Thus, the distance between the conductive member and the surface of the magnet holding member can be shortened. In addition, the thermal conductivity of the magnet holding member is high. Therefore, the heat generated in the conductive member is preferentially transmitted to the magnet holding member. The magnet holding member has a larger heat capacity than the first permanent magnet and the second permanent magnet. Therefore, excessive temperature rise of the first permanent magnet, the second permanent magnet, and the conductive member is suppressed.

  (2) In the eddy current type damper of (1), the distance between the surface of the magnet holding member and the conductive member is the same as the distance between the surface of the first permanent magnet facing the conductive member and the conductive member. preferable.

  When the surface (the outer peripheral surface or the inner peripheral surface) of the magnet holding member approaches the conductive member, the heat of the conductive member is preferentially absorbed. Therefore, it is preferable that the surface of the magnet holding member be closer to the conductive member unless interference occurs. On the other hand, the first permanent magnet forms a magnetic circuit together with the second permanent magnet to generate an eddy current in the conductive member. The stronger the eddy current, the higher the damping force of the eddy current damper, so it is preferable that the first permanent magnet be as close as possible to the conductive member. Therefore, it is preferable that the surface of the magnet holding member and the surface of the first permanent magnet facing the conductive member be as close as possible to the conductive member. The same applies to the second permanent magnet.

  (3) It is preferable that the eddy current type damper of said (1) or (2) is further equipped with the fin fixed to the magnet holding member.

  According to such a configuration, when the magnet holding member rotates, the fins also rotate. Therefore, the air in the eddy current damper is more diffused, and the excessive temperature rise of each permanent magnet and the conductive member is further suppressed. In addition, even when the magnet holding member does not rotate (when the ball nut is fixed to the conductive member), the capacity of the conductive member capable of absorbing the heat increases by the amount of provision of the fins. Therefore, excessive temperature rise of each permanent magnet and the conductive member is further suppressed.

  (4) It is preferable that the eddy current type damper of said (1)-(3) is further equipped with the fin fixed to the electrically-conductive member.

  According to such a configuration, when the conductive member does not rotate, the fins absorb or dissipate heat in the eddy current damper. When the conductive member rotates, the air in the eddy current damper is more diffused, or the fins are cooled by contact with the outside air. Thereby, excessive temperature rise of each permanent magnet and the conductive member is further suppressed.

  Hereinafter, the eddy current damper of the present embodiment will be described with reference to the drawings.

First Embodiment
FIG. 1 is an axial sectional view of the eddy current damper. Referring to FIG. 1, the eddy current damper 1 includes a conductive member 8, a magnet holding member 4, a first permanent magnet 6, a second permanent magnet 7, a screw shaft 2, and a ball nut 3. Including.

[Conductive member]
The conductive member 8 has a cylindrical shape with the screw shaft 2 as a central axis. The conductive member 8 can accommodate the magnet holding member 4, the first permanent magnet 6, the second permanent magnet 7, the ball nut 3, and the screw shaft 2. That is, the magnet holding member 4 is concentrically disposed inside the conductive member 8.

  The conductive member 8 rotatably supports the magnet holding member 4. A radial bearing 16 is provided between the magnet holding member 4 and the conductive member 8 in the radial direction of the magnet holding member 4. Further, a thrust bearing 17 is provided between the magnet holding member 4 and the conductive member 8 in the axial direction of the magnet holding member 4. Of course, the types of radial bearings and thrust bearings are not particularly limited, and may be of ball type, roller type, slide type or the like.

  FIG. 2 is a partially enlarged view of FIG. Referring to FIG. 2, the inner circumferential surface of conductive member 8 opposes first permanent magnet 6 and second permanent magnet 7 with a gap. As described later, in order to generate an eddy current on the surface (inner peripheral surface) of the conductive member 8, the conductive member 8 rotates relative to the magnet holding member 4. In order to avoid interference, a gap is provided between the conductive member 8 and the first permanent magnet 6 and the second permanent magnet 7. The fixture 14 integral with the conductive member 8 is fixed in the building support surface or in the building (see FIG. 1). Therefore, the conductive member 8 does not rotate around the screw shaft 2.

  The conductive member has conductivity. The material of the conductive member is, for example, a ferromagnetic material such as carbon steel or cast iron. In addition, the material of the conductive member may be a weak magnetic material such as ferritic stainless steel or a nonmagnetic material such as aluminum alloy, austenitic stainless steel, copper alloy or the like. The thermal conductivity of these materials is higher than that of permanent magnets.

Magnet holding member
The magnet holding member 4 has a cylindrical shape with the screw shaft 2 as a central axis. The magnet holding member 4 can accommodate the ball nut 3 and the screw shaft 2. Magnet holding member 4 includes a surface (peripheral surface) 5 and a recess 9 provided on surface 5. The surface (peripheral surface) 5 faces the conductive member 8 with a gap in order to avoid interference.

  Generally, the first permanent magnet 6 and the second permanent magnet 7 are fixed to the surface (peripheral surface) 5 of the magnet holding member. Therefore, the distance between the first permanent magnet 6 and the second permanent magnet 7 and the conductive member 8 is shorter than the distance between the surface (peripheral surface) 5 of the magnet holding member and the conductive member 8. Therefore, the heat of the conductive member 8 generated by the eddy current is easily transmitted to the first permanent magnet 6 and the second permanent magnet 7. However, the eddy current damper of the present embodiment includes the recess 9. The recess 9 includes a bottom surface 10. The distance between the bottom surface 10 and the conductive member 8 is longer than the distance between the surface (peripheral surface) 5 of the magnet holding member and the conductive member 8. The first permanent magnet 6 and the second permanent magnet 7 are fixed to the bottom surface 10. Therefore, the distance between the first permanent magnet 6 and the second permanent magnet 7 and the conductive member 8 becomes long. Thus, the heat of the conductive member 8 is less likely to be transmitted to the first permanent magnet 6 and the second permanent magnet 7.

  Also, looking at the distance between the conductive member 8 and the surface 5 of the magnet holding member and the distance between the conductive member 8 and the first permanent magnet 6 and the second permanent magnet 7, the first permanent magnet and the second permanent magnet By fixing, the distance between the conductive member 8 and the surface 5 of the magnet holding member can be shortened compared to the case where the first permanent magnet and the second permanent magnet are fixed to the surface (peripheral surface) of the magnet holding member. it can. Since the surface (peripheral surface) 5 faces the conductive member 8, the heat of the conductive member 8 is easily transmitted to the magnet holding member 4. Furthermore, the thermal conductivity of the magnet holding member is higher than the thermal conductivity of the first permanent magnet and the thermal conductivity of the second permanent magnet. Therefore, due to the characteristics of heat, the heat of the conductive member is easily transmitted to the magnet holding member having high thermal conductivity.

  With such a configuration, the heat generated in the conductive member is preferentially transmitted to the magnet holding member. The magnet holding member has a cylindrical shape and has a larger heat capacity than the first permanent magnet and the second permanent magnet. Therefore, even if the same amount of heat is transmitted, the amount of temperature increase of the magnet holding member may be smaller than the amount of temperature increase of the first permanent magnet and the second permanent magnet. In short, by dispersing the heat conventionally transferred to the first permanent magnet and the second permanent magnet to parts other than the permanent magnet of the eddy current damper, the excessive temperature rise of the conductive member is suppressed, and The temperature rise of the first permanent magnet and the second permanent magnet is also suppressed.

  The material of the magnet holding member 4 is not particularly limited. However, the material of the magnet holding member 4 is preferably steel or the like having high permeability. The material of the magnet holding member 4 is, for example, a ferromagnetic material such as carbon steel or cast iron. In this case, the magnet holding member 4 plays a role as a yoke. That is, the magnetic flux from the first permanent magnet 6 and the second permanent magnet 7 hardly leaks to the outside, and the damping force of the eddy current damper 1 increases.

  The magnet holding member 4 is fixed to the ball nut 3. Therefore, when the ball nut 3 rotates, the magnet holding member 4 also rotates, and the magnet holding member 4 can rotate relative to the conductive member 8.

  FIG. 3 is a perspective view showing the recess. Referring to FIG. 3, recesses 9 are provided along the circumferential direction of magnet holding member 4. The length of the recess 9 along the axial direction of the magnet holding member 4 is not particularly limited, but it needs to be able to accommodate the first permanent magnet 6 and the second permanent magnet 7. Further, the length of the recess 9 along the axial direction of the magnet holding member 4 is shorter than the length of the surface (peripheral surface) 5 of the magnet holding member 4. Thereby, even if the recess 9 is provided on the outer peripheral surface of the magnet holding member 4, the surface (outer peripheral surface) 5 facing the conductive member can exist.

  In FIG. 3, the case where the plurality of first permanent magnets 6 and the plurality of second permanent magnets 7 are fixed to one recess 9 is shown. However, the eddy current damper of the present embodiment is not limited to this. For example, a plurality of recesses 9 may be provided along the circumferential direction of the magnet holding member 4. The first permanent magnet 6 and the second permanent magnet 7 may be fixed to each recess 9 one by one.

[First Permanent Magnet and Second Permanent Magnet]
The first permanent magnet 6 is fixed to the recess 9. The second permanent magnet 7 is also similar to the first permanent magnet 6. The second permanent magnet 7 is adjacent to the first permanent magnet 6 in the circumferential direction of the magnet holding member 4. More specifically, the first permanent magnet 6 is adjacent to the second permanent magnet 7 with a gap in the circumferential direction of the magnet holding member 4. The size and the nature of the second permanent magnet 7 are the same as the size and the nature of the first permanent magnet 6.

  FIG. 4 is a cross-sectional view perpendicular to the axial direction of the eddy current damper. Referring to FIG. 4, the case where the plurality of first permanent magnets 6 and the plurality of second permanent magnets 7 are fixed to the magnet holding member 4 is shown. In this case, one second permanent magnet 7 is disposed between two adjacent first permanent magnets 6 with a gap. That is, the first permanent magnet 6 and the second permanent magnet 7 are alternately arranged in the circumferential direction of the magnet holding member 4.

  FIG. 5 is a partially enlarged view of FIG. Referring to FIG. 5, the magnetic poles of first permanent magnet 6 and second permanent magnet 7 are arranged in the radial direction of magnet holding member 4. The arrangement of the magnetic poles of the second permanent magnet 7 is opposite to the arrangement of the magnetic poles of the first permanent magnet 6. Specifically, in the radial direction of the magnet holding member 4, the N pole of the first permanent magnet 6 is disposed outside, and the S pole is disposed inside. Therefore, the south pole of the first permanent magnet 6 is in contact with the magnet holding member 4 (bottom surface 10 of the recess 9). On the other hand, in the radial direction of the magnet holding member 4, the N pole of the second permanent magnet 7 is disposed inside, and the S pole thereof is disposed outside. Therefore, the N pole of the second permanent magnet 7 contacts the magnet holding member 4. Such a configuration can generate an eddy current in the conductive member. This point will be described later.

  The first permanent magnet 6 and the second permanent magnet 7 are fixed to the magnet holding member 4 by an adhesive, for example. Of course, not only the adhesive but also the first permanent magnet 6 and the second permanent magnet 7 may be fixed by screws or the like.

  Referring to FIG. 2, in the radial direction of magnet holding member 4, the distance between surface 5 of conductive member 8 facing conductive member 8 and conductive member 8 faces conductive member 8 of first permanent magnet 6. The distance between the surface and the conductive member 8 is preferably the same. That is, the surface (peripheral surface) 5 of the magnet holding member is preferably present on the same curved surface as the surface of the first permanent magnet 6 facing the conductive member 8. As described above, as the surface (outer peripheral surface) 5 of the magnet holding member approaches the conductive member 8, the heat of the conductive member 8 is preferentially absorbed. Therefore, it is preferable that the surface (outer peripheral surface) 5 of the magnet holding member be closer to the inner peripheral surface of the conductive member 8 unless interference occurs. On the other hand, as described later, the first permanent magnet 6 forms a magnetic circuit together with the second permanent magnet 7 and causes the conductive member 8 to generate an eddy current. The stronger the eddy current, the higher the damping force of the eddy current damper. Therefore, it is preferable that the first permanent magnet 6 be as close as possible to the inner circumferential surface of the conductive member 8 as well. Therefore, when both the surface (peripheral surface) 5 of the magnet holding member and the surface of the first permanent magnet 6 facing the conductive member 8 approach the conductive member 8 as close as possible, the distance from the conductive member 8 becomes the same.

[Screw shaft]
Referring to FIG. 1, a screw portion is formed on the outer peripheral surface of screw shaft 2. The screw shaft 2 includes a central axis. The screw shaft 2 extends in the central axial direction. The screw shaft 2 penetrates the ball nut 3 and engages with the ball nut 3 via the ball.

[Ball nut]
The ball nut 3 meshes with the screw shaft 2. The inner circumferential surface of the ball nut 3 is formed with a screw portion that engages with the screw shaft 2. The ball nut 3 is disposed inside the magnet holding member 4 and the conductive member 8. The type of ball nut 3 is not particularly limited. The ball nut 3 may use a well-known ball nut.

  That is, the screw shaft 2 and the ball nut 3 constitute a ball screw. The ball screw converts an axial translational movement of the screw shaft 2 into a rotational movement of the ball nut 3. The fixture 15 is connected to the screw shaft 2. The fixture 15 integral with the screw shaft 2 is fixed in the building support surface or in the building. In the case where the eddy current damper 1 is installed, for example, in the seismic isolation layer between the inside of the building and the building support surface, the fixture 15 integral with the screw shaft 2 is fixed in the building and integrated with the conductive member 8 The fixture 14 is fixed to the building support surface. In the case where the eddy current type damper 1 is installed, for example, in any layer in a building, the fixture 15 integral with the screw shaft 2 is fixed to the upper beam side of any layer and integrated with the conductive member 8. The fixture 14 is fixed to the lower beam side of any layer. Therefore, the screw shaft 2 does not rotate around its central axis.

  Fixing of the fixture 15 integral with the screw shaft 2 and the fixture 14 integral with the conductive member 8 may be reverse to the above description. That is, the fixture 15 integral with the screw shaft 2 may be fixed to the building support surface, and the fixture 14 integral with the conductive member 8 may be fixed within the building.

  The screw shaft 2 can be axially advanced or retracted inside the magnet holding member 4 and the conductive member 8. Therefore, when kinetic energy is given to the eddy current damper 1 by vibration or the like, the screw shaft 2 moves in the axial direction. If the screw shaft 2 moves in the axial direction, the ball nut 3 rotates around the central axis of the screw shaft by the function of the ball screw. As the ball nut 3 rotates, the magnet holding member 4 fixed to the ball nut 3 rotates. As a result, since the first permanent magnet 6 and the second permanent magnet 7 integral with the magnet holding member 4 rotate relative to the conductive member 8, an eddy current is generated in the conductive member 8. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

  Subsequently, the generation principle of the eddy current and the generation principle of the damping force by the eddy current will be described.

[Attenuation force due to eddy current]
FIG. 6 is a schematic view showing a magnetic circuit of the eddy current damper. Referring to FIG. 6, the arrangement of the magnetic poles of the first permanent magnet 6 is opposite to the arrangement of the magnetic poles of the adjacent second permanent magnet 7. Therefore, the magnetic flux emitted from the N pole of the first permanent magnet 6 reaches the S pole of the adjacent second permanent magnet 7. The magnetic flux emitted from the N pole of the second permanent magnet 7 reaches the S pole of the adjacent first permanent magnet 6. Thus, a magnetic circuit is formed among the first permanent magnet 6, the second permanent magnet 7, the conductive member 8 and the magnet holding member 4. Since the gap between the first permanent magnet 6 and the second permanent magnet 7 and the conductive member 8 is sufficiently small, the conductive member 8 is in the magnetic field.

  When the magnet holding member 4 rotates (see the arrow in FIG. 6), the first permanent magnet 6 and the second permanent magnet 7 move relative to the conductive member 8. Therefore, the magnetic flux passing through the surface of the conductive member 8 (in FIG. 6, the inner peripheral surface of the conductive member 8 opposed to the first permanent magnet 6 and the second permanent magnet 7) changes. As a result, an eddy current is generated on the surface of the conductive member 8. When an eddy current is generated, a new magnetic flux (demagnetizing field) is generated. The new magnetic flux prevents relative rotation between the magnet holding member 4 and the conductive member 8. That is, the rotation of the magnet holding member 4 is hindered. If the rotation of the magnet holding member 4 is prevented, the rotation of the ball nut 3 fixed to the magnet holding member 4 is also prevented. If the rotation of the ball nut 3 is impeded, the axial movement of the screw shaft 2 is also impeded. This is the damping force of the eddy current damper 1. Eddy current generated by kinetic energy due to vibration or the like raises the temperature of the conductive member. That is, kinetic energy given to the eddy current damper is converted to thermal energy to obtain a damping force.

  Then, the suitable aspect and other embodiment of the eddy current type damper of this embodiment are described.

[Pole arrangement]
In the above description, the arrangement of the magnetic poles of the first permanent magnet and the second permanent magnet has been described in the case of the radial direction of the magnet holding member. However, the arrangement of the magnetic poles of the first permanent magnet and the second permanent magnet is not limited to this.

  FIG. 7 is a perspective view showing a first permanent magnet and a second permanent magnet in which the arrangement of magnetic poles is in the circumferential direction. Referring to FIG. 7, the arrangement of the magnetic poles of the first permanent magnet 6 and the second permanent magnet 7 is along the circumferential direction of the magnet holding member 4. Even in this case, the arrangement of the magnetic poles of the first permanent magnet 6 is opposite to the arrangement of the magnetic poles of the second permanent magnet 7. A ferromagnetic pole piece 11 is provided between the first permanent magnet 6 and the second permanent magnet 7.

  FIG. 8 is a schematic view showing a magnetic circuit of the eddy current damper of FIG. Referring to FIG. 8, the magnetic flux emitted from the N pole of first permanent magnet 6 passes through pole piece 11 to reach the S pole of first permanent magnet 6. The same applies to the second permanent magnet 7. A magnetic circuit is formed among the first permanent magnet 6, the second permanent magnet 7, the pole piece 11 and the conductive member 8. Thus, the damping force is obtained in the eddy current damper as described above.

[Arrangement of permanent magnet in axial direction]
In order to further increase the damping force of the eddy current damper, the eddy current generated in the conductive member may be increased. One way to generate strong eddy currents is to increase the amount of magnetic flux exiting the first and second permanent magnets. That is, the sizes of the first permanent magnet and the second permanent magnet are increased. However, the large-sized first permanent magnet and the second permanent magnet are expensive, and their attachment to the magnet holding member is not easy.

  FIG. 9 is a perspective view showing a plurality of first permanent magnets and a plurality of second permanent magnets arranged in the axial direction. Referring to FIG. 9, a plurality of first permanent magnets 6 and second permanent magnets 7 may be arranged in the axial direction of one magnet holding member 4. Thereby, the size of each of the one first permanent magnet 6 and the one second permanent magnet 7 may be small. Therefore, the cost of the first permanent magnet 6 and the second permanent magnet 7 can be reduced. In addition, attachment of the first permanent magnet 6 and the second permanent magnet 7 to the magnet holding member 4 is also easy. Further, the total size of the plurality of first permanent magnets 6 and the second permanent magnets 7 attached to the magnet holding member 4 is large. Therefore, the strength of the eddy current generated in the conductive member becomes strong.

  The circumferential arrangement of the magnet holding member 4 of the axially arranged first and second permanent magnets 6 and 7 is the same as described above. That is, the first permanent magnets 6 and the second permanent magnets 7 are alternately arranged along the circumferential direction of the magnet holding member 4, and the arrangement of the magnetic poles is reversed.

  In order to increase the damping force of the eddy current damper, the first permanent magnet 6 is preferably adjacent to the second permanent magnet 7 in the axial direction of the magnet holding member 4. In this case, the magnetic circuit is generated not only in the circumferential direction of the magnet holding member 4 but also in the axial direction. Therefore, the eddy current generated in the conductive member 8 becomes strong. As a result, the damping force of the eddy current damper is increased.

  However, the arrangement of the first permanent magnet 6 and the second permanent magnet 7 in the axial direction of the magnet holding member 4 is not particularly limited. That is, in the axial direction of the magnet holding member 4, the first permanent magnet 6 may be disposed adjacent to the first permanent magnet 6 or may be disposed adjacent to the second permanent magnet 7.

  In the first embodiment described above, the case where the magnet holding member is disposed inside the conductive member, the first permanent magnet and the second permanent magnet are attached to the outer peripheral surface of the magnet holding member, and the magnet holding member rotates . However, the eddy current damper of the present embodiment is not limited to this.

Second Embodiment
In the eddy current damper of the second embodiment, the magnet holding member is disposed outside the conductive member and does not rotate. Eddy current is generated by rotation of the inner conductive member.

  FIG. 10 is a cross-sectional view in a plane along the axial direction of the eddy current damper of the second embodiment. FIG. 11 is a cross-sectional view in a plane perpendicular to the axial direction of the eddy current damper of the second embodiment. Referring to FIGS. 10 and 11, magnet holding member 4 can accommodate conductive member 8, ball nut 3 and screw shaft 2. The first permanent magnet 6 and the second permanent magnet 7 are attached to the inner circumferential surface of the magnet holding member 4. Therefore, the outer peripheral surface of the conductive member 8 opposes the first permanent magnet 6, the second permanent magnet 7, and the surface (inner peripheral surface) 5 of the magnet holding member 4 with a gap.

  In the second embodiment, the magnet holding member 4 does not rotate around the screw shaft 2. On the other hand, the ball nut 3 is fixed to the conductive member 8. Therefore, when the ball nut 3 rotates, the conductive member 8 rotates. Even in such a configuration, as described above, since the first permanent magnet 6 and the second permanent magnet 7 integral with the magnet holding member 4 rotate relative to the conductive member 8, an eddy current is generated in the conductive member 8 Occurs. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

  Further, in the eddy current damper of the second embodiment, the magnet holding member 4 is disposed outside the conductive member 8. That is, the magnet holding member 4 is disposed on the outermost side and contacts the outside air. Thereby, the magnet holding member 4 is cooled by external air. Therefore, the first permanent magnet and the second permanent magnet can be cooled through the magnet holding member 4. As a result, the temperature rise of the conductive member, the first permanent magnet and the second permanent magnet can be suppressed.

Third Embodiment
In the eddy current damper of the third embodiment, the magnet holding member is disposed inside the conductive member and does not rotate. An eddy current is generated by rotation of the outer conductive member.

  FIG. 12 is a cross-sectional view of a surface of the eddy current damper of the third embodiment along the axial direction. FIG. 13 is a partially enlarged view of FIG. Referring to FIGS. 12 and 13, the conductive member 8 can accommodate the magnet holding member 4, the ball nut 3 and the screw shaft 2. The first permanent magnet 6 and the second permanent magnet 7 are attached to the outer peripheral surface of the magnet holding member 4. Therefore, the inner peripheral surface of the conductive member 8 opposes the first permanent magnet 6, the second permanent magnet 7 and the surface (outer peripheral surface) 5 of the magnet holding member 4 with a gap.

  In the third embodiment, the magnet holding member 4 does not rotate around the screw shaft 2. On the other hand, the ball nut 3 is connected to the conductive member 8. Therefore, when the ball nut 3 rotates, the conductive member 8 rotates. Even in such a configuration, as described above, since the first permanent magnet 6 and the second permanent magnet 7 integral with the magnet holding member 4 rotate relative to the conductive member 8, an eddy current is generated in the conductive member 8 Occurs. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

  Further, in the eddy current damper of the third embodiment, the conductive member 8 is disposed outside the magnet holding member 4. That is, the conductive member 8 is disposed at the outermost side to be in contact with the outside air. In addition, the conductive member 8 rotates around the screw shaft 2. Thus, the rotating conductive member 8 is efficiently cooled by the outside air. Therefore, the temperature rise of the conductive member 8 can be suppressed. As a result, temperature rise of the first permanent magnet and the second permanent magnet can be suppressed.

Fourth Embodiment
In the eddy current damper of the fourth embodiment, the conductive member is disposed inside the magnet holding member and does not rotate. Eddy current is generated by rotation of the outer magnet holding member.

  FIG. 14 is a cross-sectional view of a surface of the eddy current damper of the fourth embodiment along the axial direction. Referring to FIG. 14, magnet holding member 4 can accommodate conductive member 8, ball nut 3 and screw shaft 2. The first permanent magnet 6 and the second permanent magnet 7 are attached to the inner circumferential surface of the magnet holding member 4. Therefore, the outer peripheral surface of the conductive member 8 opposes the first permanent magnet 6, the second permanent magnet 7, and the surface (inner peripheral surface) 5 of the magnet holding member 4 with a gap.

  In the fourth embodiment, the conductive member 8 does not rotate around the screw shaft 2. On the other hand, the ball nut 3 is fixed to the magnet holding member 4. Therefore, when the ball nut 3 rotates, the magnet holding member 4 rotates. Even in such a configuration, as described above, since the first permanent magnet 6 and the second permanent magnet 7 integral with the magnet holding member 4 rotate relative to the conductive member 8, an eddy current is generated in the conductive member 8 Occurs. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

  Further, in the eddy current damper of the fourth embodiment, the magnet holding member 4 is disposed outside the conductive member 8. That is, the magnet holding member 4 is disposed on the outermost side and contacts the outside air. Further, the magnet holding member 4 rotates around the screw shaft 2. Thus, the rotating magnet holding member 4 is efficiently cooled by the outside air. Therefore, the first permanent magnet and the second permanent magnet can be cooled through the magnet holding member 4. As a result, temperature rise of the first permanent magnet and the second permanent magnet can be suppressed.

[fin]
In order to further enhance the cooling effect of the conductive member and each permanent magnet, the eddy current damper may include fins. Below, the case where a fin is provided in the eddy current type damper of a 1st embodiment is explained as an example. However, the eddy current dampers of the second to fourth embodiments can also include the same fins as those described below.

  FIG. 15 is a cross-sectional view of an eddy current damper including fins. Referring to FIG. 15, fins 13 are fixed to the outer peripheral surface of magnet holding member 4. When the magnet holding member 4 rotates, the fins 13 also rotate around the central axis of the magnet holding member 4. The rotation of the fins 13 causes the air in the eddy current damper to flow, and the heat of the conductive member 8 and the permanent magnets is diffused. Therefore, excessive temperature rise of the conductive member and each permanent magnet is further suppressed. Even when the magnet holding member 4 does not rotate, the capacity capable of absorbing the heat from the conductive member is increased by the amount of the fins provided. Therefore, excessive temperature rise of each permanent magnet and the conductive member is further suppressed.

  FIG. 16 is a cross sectional view showing another embodiment of the fin. Referring to FIG. 16, fins 13 are fixed to the inner circumferential surface of conductive member 8. The conductive member 8 does not rotate around the axis of the magnet holding member 4. In this case, the fins 13 absorb the heat in the eddy current damper. Therefore, excessive temperature rise of the conductive member and each permanent magnet is further suppressed. When the conductive member 8 rotates, the fins 13 also rotate, so the air in the eddy current damper flows, and the heat of the conductive member 8 and each permanent magnet is diffused. Therefore, excessive temperature rise of the conductive member and each permanent magnet is further suppressed.

  FIG. 17 is a cross-sectional view showing another embodiment of the fin. Referring to FIG. 17, fins 13 are fixed to the outer peripheral surface of conductive member 8. In this case, the fins 13 release the heat of the conductive member 8 to the outside. As a result, the temperature of the conductive member 8 is lowered, and the conductive member 8 can absorb the heat of each permanent magnet. Therefore, excessive temperature rise of the conductive member and each permanent magnet is further suppressed. Even when the conductive member 8 rotates, since the rotating fins 13 contact the outside air, the fins are cooled and the heat of the conductive member 8 is absorbed. Therefore, excessive temperature rise of the conductive member and each permanent magnet is further suppressed.

  The number of fins 13 is not particularly limited. For example, a plurality of fins 13 may be arranged in the circumferential direction of the magnet holding member 4. Moreover, you may use combining the fin shown to FIGS. 15-17.

  The eddy current damper of the present embodiment has been described above. In addition, it goes without saying that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the present invention.

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

1: Eddy current type damper 2: Screw shaft 3: Ball nut 4: Magnet holding member 5: Surface 6: First permanent magnet 7: Second permanent magnet 8: Conductive member 9: Recess 10: Bottom surface 11: Pole piece 13: Fins 14: Fittings (one piece with the conductive member)
15: Attachment (Integrated with screw shaft)
16: Radial bearing 17: Thrust bearing

Claims (4)

A cylindrical conductive member having conductivity;
A cylindrical magnet holding member including a surface facing the conductive member with a gap therebetween and a recess provided on the surface;
A first permanent magnet fixed to the recess and facing the conductive member with a gap therebetween;
A second permanent member fixed to the recess and facing the conductive member with a gap, adjacent to the first permanent magnet in the circumferential direction of the magnet holding member, and in which the arrangement of the first permanent magnet and the magnetic pole is reversed With a magnet,
Screw shaft,
And a ball nut fixed to the magnet holding member or the conductive member and engaged with the screw shaft.
The thermal conductivity of the magnet holding member is higher than the thermal conductivity of the first permanent magnet and the thermal conductivity of the second permanent magnet. An eddy current damper according to claim 1, wherein
The distance between the surface of the magnet holding member and the conductive member is the same as the distance between the surface of the first permanent magnet facing the conductive member and the conductive member. The eddy current damper according to claim 1, further comprising:
An eddy current damper, comprising a fin fixed to the magnet holding member. The eddy current damper according to any one of claims 1 to 3, further comprising:
An eddy current damper comprising a fin fixed to the conductive member.

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