JP2019078331A - Eddy current-type damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an eddy current type damper capable of suppressing a decrease in vibration damping performance and a decrease in durability due to a temperature rise of a ball nut. An eddy current type damper 1 has a screw shaft 7, a plurality of first permanent magnets 3, a plurality of second permanent magnets 4, a cylindrical magnet holding member 2, and a cylindrical shape having conductivity. A conductive member 5, a ball nut 6 that meshes with a screw shaft 7, and a heat insulating member 12 are provided. The first permanent magnets 3 are arranged around the screw shaft 7 along the circumferential direction. The second permanent magnet 4 is arranged between the first permanent magnets 3, and the arrangement of the first permanent magnet 3 and the magnetic pole is reversed. The magnet holding member 2 holds the first permanent magnet 3 and the second permanent magnet 4. The conductive member 5 faces the first permanent magnet 3 and the second permanent magnet 4 with a gap. The ball nut 6 is fixed to the magnet holding member 2. The heat insulating member 12 is provided at a mounting portion between the ball nut 6 and the magnet holding member 2. [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 (eg, 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. 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.

  A conventional eddy current type 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 is conductive. Hereinafter, the hysteresis material is also referred to as a conductive member. The main cylinder is also referred to as a magnet holding member. The hysteresis material faces the plurality of permanent magnets and is capable of relative rotation. When kinetic energy is given to the eddy current type damper, the sub cylinder and the ball nut move in the axial direction by the guidance of the main cylinder, 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 damper of Patent Document 1, a plurality of permanent magnets are arranged along the circumferential direction. When kinetic energy is given to the damper, the conductive member (hysteresis material) rotates in the magnetic field generated by each of the permanent magnets. At this time, eddy currents are generated in the regions of the surface of the conductive member facing the respective permanent magnets. Thereby, a damping force is applied to the rotating conductive member, and a damping force is generated. Furthermore, each of the regions where the eddy current is generated generates heat. Therefore, the temperature of the conductive member rises. In addition, the temperature of the magnet holding member (main cylinder) close to the heat generating surface of the conductive member gradually rises due to the radiation heat from the conductive member.

  Here, in an eddy current type damper used as a vibration control device, a screw shaft or a ball nut reciprocates in the axial direction in order to damp the vibration. At that time, it is important to be able to smoothly convert the linear motion and the rotational motion by the ball screw. In particular, it is important that backlash does not occur or unbalanced load does not occur when switching between reciprocating movements. Therefore, extremely high dimensional accuracy is required for the engagement portion between the ball nut and the screw shaft.

  However, in the case of the eddy current damper of Patent Document 1, the heat of the magnet holding member is transmitted to the ball nut. This is because the ball nut is in sliding contact with the magnet holding member. Therefore, the temperature of the ball nut rises. In this case, the ball nut thermally expands. When the ball nut thermally expands, the dimensional accuracy of the meshing portion is deteriorated as a result. As a result, the motion conversion efficiency by the ball screw may be reduced, and the vibration damping performance may be reduced.

  Usually, a lubricant is supplied to the engagement portion between the ball nut and the screw shaft. The purpose of this is to reduce the contact resistance of the meshing portion by the lubricant. However, if the temperature of the ball nut rises, the temperature of the lubricant also rises. In this case, the properties of the lubricant are lost, and the screw shaft may be seized on the ball nut.

  Usually, high hardness steel is used for the ball nut. This is to increase the wear resistance of the engagement portion. However, if the temperature of the ball nut rises excessively, the ball nut softens. In this case, there is a possibility that the wear resistance of the engagement portion may be reduced.

  In short, in the conventional eddy current type damper, there is a possibility that the damping performance against vibration may be deteriorated or the durability may be deteriorated due to the temperature rise of the ball nut due to the temperature rise of the conductive member.

  An object of the present invention is to provide an eddy current damper that can suppress the deterioration of vibration damping performance and the deterioration of durability due to the temperature rise of a ball nut.

  The eddy current damper of the present embodiment is disposed between a screw shaft, a plurality of first permanent magnets arranged along a circumferential direction around the screw shaft, and the first permanent magnets, A plurality of second permanent magnets in which the arrangement of the magnet and the magnetic pole is reversed, a cylindrical magnet holding member holding the first permanent magnet and the second permanent magnet, and conductivity, the first permanent magnet and the second permanent When a cylindrical conductive member opposed to a magnet with a gap is provided, a ball nut fixed to a magnet holding member or a conductive member and meshed with a screw shaft, and a ball nut fixed to a magnet holding member, the ball nut and the magnet holding A heat conduction suppressing mechanism is provided at an attachment portion with the member, and when the ball nut is fixed to the conductive member, provided at the attachment portion between the ball nut and the conductive member.

  According to the eddy current damper of the present embodiment, even if an eddy current is generated in the conductive member and the temperature of the conductive member rises, the temperature rise of the ball nut is suppressed by the heat conduction suppressing mechanism. Therefore, it is possible to suppress a decrease in vibration damping performance and a decrease in durability due to the temperature rise of the ball nut.

FIG. 1 is a cross-sectional view of the eddy current damper in a plane along the axial direction. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is a cross-sectional view in a plane perpendicular to the axial direction of the eddy current damper. FIG. 4 is a partially enlarged view of FIG. FIG. 5 is a perspective view showing a first permanent magnet and a second permanent magnet. 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 a surface of the eddy current damper of the fifth embodiment along the axial direction. FIG. 16 is a cross-sectional view of a surface of the eddy current damper of the sixth embodiment along the axial direction. FIG. 17 is a cross-sectional view of a surface of the eddy current damper of the seventh embodiment taken along the axial direction. FIG. 18 is a cross-sectional view of a surface of the eddy current damper of the eighth embodiment taken along the axial direction. FIG. 19 is a cross-sectional view of a surface of the eddy current damper of the ninth embodiment taken along the axial direction.

  The eddy current damper according to the present embodiment includes a screw shaft, a plurality of first permanent magnets, a plurality of second permanent magnets, a cylindrical magnet holding member, a cylindrical conductive member having conductivity, and a screw. A ball nut engaged with the shaft, and a heat conduction suppressing mechanism. The first permanent magnets are arranged circumferentially around the screw axis. The second permanent magnet is disposed between the first permanent magnets, and the arrangement of the first permanent magnet and the magnetic pole is reversed. The magnet holding member holds the first permanent magnet and the second permanent magnet. The conductive member opposes the first permanent magnet and the second permanent magnet with a gap. The ball nut is fixed to the magnet holding member or the conductive member. When the ball nut is fixed to the magnet holding member, the heat conduction suppressing mechanism is provided at the mounting portion of the ball nut and the magnet holding member. When the ball nut is fixed to the conductive member, the heat conduction suppressing mechanism is provided at the attachment portion between the ball nut and the conductive member.

  According to the eddy current damper of the present embodiment, when kinetic energy is given to the damper, the screw shaft moves in the axial direction. The axial movement of the screw shaft causes the ball nut to rotate. Thereby, the conductive member rotates relative to the first and second permanent magnets in the magnetic field generated by each of the first and second permanent magnets. At this time, eddy currents are generated in the regions of the surface of the conductive member facing the respective first and second permanent magnets. Thereby, a damping force is applied to the rotating conductive member, and a damping force is generated. Furthermore, each of the regions where the eddy current is generated generates heat. Therefore, the temperature of the conductive member rises. In addition, the temperature of the magnet holding member adjacent to the heat generating surface of the conductive member is also gradually raised by the radiant heat from the conductive member.

  Here, when the ball nut is fixed to the magnet holding member, heat conduction from the magnet holding member to the ball nut is suppressed by the heat conduction suppressing mechanism provided in the mounting portion between the ball nut and the magnet holding member. When the ball nut is fixed to the conductive member, heat conduction from the conductive member to the ball nut is suppressed by the heat conduction suppressing mechanism provided in the mounting portion between the ball nut and the conductive member. In any case, the temperature rise of the ball nut is suppressed.

  In that case, the thermal expansion of the ball nut is suppressed, and the dimensional accuracy of the engagement portion between the ball nut and the screw shaft is secured. Therefore, the motion conversion efficiency by the ball screw can be secured. Further, the temperature rise of the lubricant present in the meshing portion is suppressed. Therefore, the characteristics of the lubricant can be secured. Furthermore, the softening of the ball nut is suppressed. Therefore, it is possible to suppress a decrease in vibration damping performance and a decrease in durability due to the temperature rise of the ball nut.

  The above-described eddy current damper of the present embodiment can adopt any of the following configurations (1) to (4).

  (1) The magnet holding member is disposed inside the conductive member. The first permanent magnet and the second permanent magnet are attached to the outer circumferential surface of the magnet holding member. A ball nut is fixed to the magnet holding member.

  In this case, the inner circumferential surface of the conductive member faces the first and second permanent magnets with a gap. A heat conduction suppressing mechanism is provided at the mounting portion between the ball nut and the magnet holding member. The axial movement of the screw shaft rotates the ball nut and the magnet holding member. On the other hand, the conductive member does not rotate. As a result, the magnetic flux passing through the conductive member from the first permanent magnet and the second permanent magnet changes, and an eddy current is generated on the inner circumferential surface of the conductive member. A demagnetizing field is generated by the eddy current, and a reaction force (braking force) is applied to the rotating magnet holding member. As a result, the screw shaft receives a damping force.

  Further, in this case, the conductive member is disposed outside the magnet holding member to be in contact with the outside air. Thereby, the conductive member is cooled by the outside air. As a result, the temperature rise of the conductive member can be suppressed.

  (2) The conductive member is disposed inside the magnet holding member. The first permanent magnet and the second permanent magnet are attached to the inner circumferential surface of the magnet holding member. The ball nut is fixed to the conductive member.

  In this case, the outer circumferential surface of the conductive member faces the first and second permanent magnets with a gap. A heat conduction suppressing mechanism is provided at the mounting portion between the ball nut and the conductive member. The axial movement of the screw shaft rotates the ball nut and the conductive member. On the other hand, the magnet holding member does not rotate. As a result, the magnetic flux passing through the conductive member from the first permanent magnet and the second permanent magnet changes, and an eddy current is generated on the outer peripheral surface of the conductive member. A demagnetizing field is generated by this eddy current, and a reaction force is given to the rotating conductive member. As a result, the screw shaft receives a damping force.

  Further, in this case, the magnet holding member is disposed outside the conductive member and is in contact with the outside air. Thereby, the magnet holding member is cooled by the outside air. As a result, the temperature rise of the first and second permanent magnets can be suppressed.

  (3) The magnet holding member is disposed inside the conductive member. The first permanent magnet and the second permanent magnet are attached to the outer circumferential surface of the magnet holding member. The ball nut is fixed to the conductive member.

  In this case, the inner circumferential surface of the conductive member faces the first and second permanent magnets with a gap. A heat conduction suppressing mechanism is provided at the mounting portion between the ball nut and the conductive member. The axial movement of the screw shaft rotates the ball nut and the conductive member. On the other hand, the magnet holding member does not rotate. As a result, the magnetic flux passing through the conductive member from the first and second permanent magnets changes, and an eddy current is generated on the inner peripheral surface of the conductive member. A demagnetizing field is generated by this eddy current, and a reaction force is given to the rotating conductive member. As a result, the screw shaft receives a damping force.

  Further, in this case, the conductive member is disposed outside the magnet holding member to be in contact with the outside air. Thus, the rotating conductive member is efficiently cooled by the outside air. As a result, the temperature rise of the conductive member can be suppressed.

  (4) The conductive member is disposed inside the magnet holding member. The first permanent magnet and the second permanent magnet are attached to the inner circumferential surface of the magnet holding member. A ball nut is fixed to the magnet holding member.

  In this case, the outer circumferential surface of the conductive member faces the first and second permanent magnets with a gap. A heat conduction suppressing mechanism is provided at the mounting portion between the ball nut and the magnet holding member. The axial movement of the screw shaft rotates the ball nut and the magnet holding member. On the other hand, the conductive member does not rotate. As a result, the magnetic flux passing through the conductive member from the first and second permanent magnets changes, and an eddy current is generated on the outer peripheral surface of the conductive member. A demagnetizing field is generated by this eddy current, and a reaction force is given to the rotating magnet holding member. As a result, the screw shaft receives a damping force.

  Further, in this case, the magnet holding member is disposed outside the conductive member and is in contact with the outside air. Thus, the rotating magnet holding member is efficiently cooled by the outside air. As a result, the temperature rise of the first and second permanent magnets can be suppressed.

  In the eddy current damper of the present embodiment, when the ball nut is fixed to the magnet holding member, the heat conduction suppressing mechanism includes a heat insulating member provided between the mounting surface of the ball nut and the mounting surface of the magnet holding member. Is preferred. In this case, the heat conduction from the magnet holding member to the ball nut is blocked by the heat insulating member. When the ball nut is fixed to the conductive member, the heat conduction suppressing mechanism preferably includes a heat insulating member provided between the mounting surface of the ball nut and the mounting surface of the conductive member. In this case, heat conduction from the conductive member to the ball nut is blocked by the heat insulating member. In any case, the temperature rise of the ball nut can be further suppressed.

  The material of the heat insulating member is not particularly limited. Typically, the material of the heat insulating member is glass fiber, rock wool, calcium silicate or the like. The heat insulating member may be formed by mixing glass fibers and a synthetic resin and formed into a plate, or may be formed by mixing rock wool and a synthetic resin and formed into a plate.

  In the eddy current damper of the present embodiment, when the ball nut is fixed to the magnet holding member, the heat conduction suppressing mechanism is a recess formed in at least one of the mounting surface of the ball nut and the mounting surface of the magnet holding member. Is preferred. In this case, since the contact area between the magnet holding member and the ball nut is small, heat conduction from the magnet holding member to the ball nut is suppressed. When the ball nut is fixed to the conductive member, the heat conduction suppressing mechanism preferably includes a recess formed in at least one of the mounting surface of the ball nut and the mounting surface of the conductive member. In this case, since the contact area between the conductive member and the ball nut is small, heat conduction from the conductive member to the ball nut is suppressed. In any case, the temperature rise of the ball nut can be suppressed by simply forming the recess.

  The shape of the recess is not particularly limited. As a typical example, the recess is a groove along the circumferential direction around the screw axis. The recess may be a radial groove centered on the screw axis. The recess may be a hole.

  In the eddy current damper of the present embodiment, a plurality of first permanent magnets are disposed along the axial direction of the magnet holding member, and a plurality of second permanent magnets are disposed along the axial direction of the magnet holding member. It is also good.

  In this case, even if the size of one first permanent magnet and one second permanent magnet is small, the total size of the plurality of first and second permanent magnets is large. Therefore, the cost of the first and second permanent magnets can be reduced while increasing the damping force of the eddy current damper. In addition, attachment of the first and second permanent magnets to the magnet holding member is easy.

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

First Embodiment
FIG. 1 is a cross-sectional view of the eddy current damper in a plane along the axial direction. FIG. 2 is a partially enlarged view of FIG. Referring to FIGS. 1 and 2, the eddy current damper 1 includes a magnet holding member 2, a plurality of first permanent magnets 3, a plurality of second permanent magnets 4, a conductive member 5, and a ball nut 6. , Screw shaft 7 and a heat insulating member 12 (see FIG. 2).

Magnet holding member
The magnet holding member 2 has a cylindrical shape with the screw shaft 7 as a central axis. The magnet holding member 2 can accommodate the ball nut 6 and the screw shaft 7. The material of the magnet holding member 2 is not particularly limited. However, the material of the magnet holding member 2 is preferably steel or the like having high permeability. The material of the magnet holding member 2 is, for example, a ferromagnetic material such as carbon steel or cast iron. In this case, the magnet holding member 2 plays a role as a yoke. That is, the magnetic flux from the first permanent magnet 3 and the second permanent magnet 4 hardly leaks to the outside, and the damping force of the eddy current damper 1 is increased. As described later, the magnet holding member 2 is rotatable with respect to the conductive member 5.

[First Permanent Magnet and Second Permanent Magnet]
FIG. 3 is a cross-sectional view in a plane perpendicular to the axial direction of the eddy current damper. FIG. 4 is a partially enlarged view of FIG. FIG. 5 is a perspective view showing a first permanent magnet and a second permanent magnet. Referring to FIGS. 3 to 5, the plurality of first permanent magnets 3 and the plurality of second permanent magnets 4 are attached to the outer circumferential surface of the magnet holding member 2. The first permanent magnet 3 is arranged along the circumferential direction of the magnet holding member 2 around a screw axis. Similarly, the second permanent magnets 4 are arranged along the circumferential direction of the magnet holding member 2 around the screw shaft. The second permanent magnet 4 is disposed between the first permanent magnets 3. That is, the first permanent magnets 3 and the second permanent magnets 4 are alternately arranged along the circumferential direction of the magnet holding member 2.

  The magnetic poles of the first permanent magnet 3 and the second permanent magnet 4 are disposed in the radial direction of the magnet holding member 2. The arrangement of the magnetic poles of the second permanent magnet 4 is opposite to the arrangement of the magnetic poles of the first permanent magnet 3. For example, referring to FIGS. 4 and 5, in the radial direction of magnet holding member 2, the N pole of first permanent magnet 3 is disposed outside, and the S pole thereof is disposed inside. Therefore, the south pole of the first permanent magnet 3 is in contact with the magnet holding member 2. On the other hand, in the radial direction of the magnet holding member 2, the N pole of the second permanent magnet 4 is disposed inside, and the S pole thereof is disposed outside. Therefore, the N pole of the second permanent magnet 4 contacts the magnet holding member 2.

  The size and the nature of the second permanent magnet 4 are the same as the size and the nature of the first permanent magnet 3. The first permanent magnet 3 and the second permanent magnet 4 are fixed to the magnet holding member 2 by an adhesive, for example. Of course, not only the adhesive but also the first permanent magnet 3 and the second permanent magnet 4 may be fixed by screws or the like.

[Conductive member]
Referring to FIGS. 1 and 2, conductive member 5 has a cylindrical shape with screw shaft 7 as a central axis. The conductive member 5 can accommodate the magnet holding member 2, the first permanent magnet 3, the second permanent magnet 4, the ball nut 6, and the screw shaft 7. That is, the magnet holding member 2 is concentrically disposed inside the conductive member 5. The inner circumferential surface of the conductive member 5 opposes the first permanent magnet 3 and the second permanent magnet 4 with a gap. As described later, in order to generate an eddy current on the surface (inner peripheral surface) of the conductive member 5, the conductive member 5 rotates relative to the magnet holding member 2. Therefore, a gap is provided between the conductive member 5 and the first permanent magnet 3 and the second permanent magnet 4. The fixture 8 a is connected to the conductive member 5. The fixture 8a integral with the conductive member 5 is fixed in the building support surface or in the building. Therefore, the conductive member 5 does not rotate around the screw shaft 7.

  The conductive member 5 has conductivity. The material of the conductive member 5 is, for example, a ferromagnetic material such as carbon steel or cast iron. In addition, the material of the conductive member 5 may be a weak magnetic material such as ferritic stainless steel, or may be a nonmagnetic material such as aluminum alloy, austenitic stainless steel, copper alloy or the like.

  The conductive member 5 rotatably supports the magnet holding member 2. For example, referring to FIG. 1, a radial bearing 9 is provided between magnet holding member 2 and conductive member 5 in the radial direction of magnet holding member 2. Further, a thrust bearing 10 is provided between the magnet holding member 2 and the conductive member 5 in the axial direction of the magnet holding member 2. The types of the radial bearing 9 and the thrust bearing 10 are not particularly limited, and it is a matter of course that a ball type, a roller type, a sliding type or the like may be used.

[Ball nut]
The ball nut 6 is disposed inside the magnet holding member 2 and the conductive member 5. The ball nut 6 is fixed to the magnet holding member 2. Therefore, when the ball nut 6 rotates, the magnet holding member 2 also rotates. The type of ball nut 6 is not particularly limited. The ball nut 6 may use a well-known ball nut. A threaded portion is formed on the inner circumferential surface of the ball nut 6.

  Referring to FIG. 2, in the present embodiment, the ball nut 6 has a flange 6a. The inner end face 6 b of the flange 6 a of the ball nut 6 faces one end face 2 a of the magnet holding member 2. Between the inner end face 6 b of the flange 6 a of the ball nut 6 and the end face 2 a of the magnet holding member 2, an annular plate-like heat insulating member 12 is provided. In a state in which the heat insulating member 12 is sandwiched between the inner end surface 6b of the flange 6a of the ball nut 6 and the end surface 2a of the magnet holding member 2, the flange 6a of the ball nut 6 is attached to the magnet holding member 2 by a bolt (not shown). It is fixed. That is, the heat insulating member 12 is provided at the mounting portion between the ball nut 6 and the magnet holding member 2.

[Screw shaft]
The screw shaft 7 penetrates the ball nut 6 and engages with the ball nut 6 through the ball. On the outer peripheral surface of the screw shaft 7, a screw portion corresponding to the screw portion of the ball nut 6 is formed. The screw shaft 7 and the ball nut 6 constitute a ball screw. The ball screw converts the axial movement of the screw shaft 7 into the rotational movement of the ball nut 6. The fixture 8 b is connected to the screw shaft 7. The fixture 8b integral with the screw shaft 7 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 a building and a building support surface, the fixture 8b integral with the screw shaft 7 is fixed in the building and integrated with the conductive member 5 The fixture 8a 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 8b integral with the screw shaft 7 is fixed to the upper beam side of any layer and integrated with the conductive member 5 The fixture 8a is fixed to the lower beam side between arbitrary layers. Therefore, the screw shaft 7 does not rotate around the axis.

  Fixing of the fixture 8b integral with the screw shaft 7 and the fixture 8a integral with the conductive member 5 may be reversed to the above description. That is, the fixture 8b integral with the screw shaft 7 may be fixed to the building support surface, and the fixture 8a integral with the conductive member 5 may be fixed within the building.

  The screw shaft 7 is movable axially forward and backward inside the magnet holding member 2 and the conductive member 5. Therefore, when kinetic energy is given to the eddy current damper 1 by vibration or the like, the screw shaft 7 moves in the axial direction. When the screw shaft 7 moves in the axial direction, the ball nut 6 rotates around the screw shaft 7 by the action of the ball screw. As the ball nut 6 rotates, the magnet holding member 2 rotates. As a result, since the first permanent magnet 3 and the second permanent magnet 4 integral with the magnet holding member 2 rotate relative to the conductive member 5, an eddy current is generated in the conductive member 5. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

  According to the eddy current damper 1 of the present embodiment, the heat conduction from the magnet holding member 2 to the ball nut 6 is blocked by the heat insulating member 12 provided in the mounting portion between the ball nut 6 and the magnet holding member 2. . That is, the heat insulating member 12 functions as a heat conduction suppressing mechanism. Thereby, the temperature rise of the ball nut 6 is suppressed. Therefore, it is possible to suppress the deterioration of the vibration damping performance and the deterioration of the durability due to the temperature rise of the ball nut 6.

  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 3 is opposite to the arrangement of the magnetic poles of the adjacent second permanent magnet 4. Therefore, the magnetic flux emitted from the N pole of the first permanent magnet 3 reaches the S pole of the adjacent second permanent magnet 4. The magnetic flux emitted from the N pole of the second permanent magnet reaches the S pole of the adjacent first permanent magnet 3. Thus, a magnetic circuit is formed among the first permanent magnet 3, the second permanent magnet 4, the conductive member 5 and the magnet holding member 2. Since the gap between the first and second permanent magnets 3 and 4 and the conductive member 5 is sufficiently small, the conductive member 5 is in the magnetic field.

  When the magnet holding member 2 rotates (see the arrow in FIG. 6), the first permanent magnet 3 and the second permanent magnet 4 move relative to the conductive member 5. Therefore, the magnetic flux passing through the surface of the conductive member 5 (the inner peripheral surface of the conductive member 5 opposed to the first permanent magnet 3 and the second permanent magnet 4 in FIG. 6) changes. As a result, an eddy current is generated on the surface of the conductive member 5 (the inner peripheral surface of the conductive member 5 in FIG. 6). 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 2 (the first permanent magnet 3 and the second permanent magnet 4) and the conductive member 5. In the case of this embodiment, the rotation of the magnet holding member 2 is prevented. If rotation of the magnet holding member 2 is prevented, rotation of the ball nut 6 integral with the magnet holding member 2 is also prevented. If the rotation of the ball nut 6 is blocked, the axial movement of the screw shaft 7 is also blocked. 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.

  According to the eddy current damper of the present embodiment, the arrangement of the magnetic poles of the first permanent magnet is reversed to the arrangement of the magnetic poles of the second permanent magnet adjacent to the first permanent magnet in the circumferential direction of the magnet holding member . Therefore, a magnetic field due to the first permanent magnet and the second permanent magnet is generated in the circumferential direction of the magnet holding member. Further, by arranging a plurality of first permanent magnets and second permanent magnets in the circumferential direction of the magnet holding member, the amount of magnetic flux reaching the conductive member is increased. As a result, the eddy current generated in the conductive member is increased, and the damping force of the eddy current damper is increased.

[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 3 and the second permanent magnet 4 is along the circumferential direction of the magnet holding member 2. Even in this case, the arrangement of the magnetic poles of the first permanent magnet 3 is opposite to the arrangement of the magnetic poles of the second permanent magnet 4. A ferromagnetic pole piece 11 is provided between the first permanent magnet 3 and the second permanent magnet 4.

  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 3 passes through pole piece 11 to reach the S pole of first permanent magnet 3. The same applies to the second permanent magnet 4. Thus, a magnetic circuit is formed among the first permanent magnet 3, the second permanent magnet 4, the pole piece 11 and the conductive member 5. Thus, the damping force is obtained in the eddy current damper 1 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 large 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 may be 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 3 and second permanent magnets 4 may be arranged in the axial direction of one magnet holding member 2. Thereby, the size of each of the one first permanent magnet 3 and the one second permanent magnet 4 may be small. On the other hand, the total size of the plurality of first permanent magnets 3 and the second permanent magnets 4 attached to the magnet holding member 2 is large. Therefore, the cost of the first permanent magnet 3 and the second permanent magnet 4 can be reduced. Moreover, attachment to the magnet holding member 2 of the 1st permanent magnet 3 and the 2nd permanent magnet 4 is also easy.

  The circumferential arrangement of the magnet holding member 2 of the axially arranged first and second permanent magnets 3 and 4 is the same as described above. That is, the first permanent magnets 3 and the second permanent magnets 4 are alternately arranged along the circumferential direction of the magnet holding member 2.

  In order to increase the damping force of the eddy current damper 1, the first permanent magnet 3 is preferably adjacent to the second permanent magnet 4 in the axial direction of the magnet holding member 2. In this case, the magnetic circuit is generated not only in the circumferential direction of the magnet holding member 2 but also in the axial direction. Therefore, the eddy current generated in the conductive member 5 is increased. As a result, the damping force of the eddy current damper 1 is increased.

  However, the arrangement of the first permanent magnet 3 and the second permanent magnet 4 in the axial direction of the magnet holding member 2 is not particularly limited. That is, in the axial direction of the magnet holding member 2, the first permanent magnet 3 may be disposed adjacent to the first permanent magnet 3 or may be disposed adjacent to the second permanent magnet 4.

  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 further did. 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 2 can accommodate conductive member 5, ball nut 6 and screw shaft 7. The first permanent magnet 3 and the second permanent magnet 4 are attached to the inner peripheral surface of the magnet holding member 2. Therefore, the outer peripheral surface of the conductive member 5 faces the first permanent magnet 3 and the second permanent magnet 4 with a gap.

  The fixture 8 a shown in FIG. 1 is connected to the magnet holding member 2. Therefore, the magnet holding member 2 does not rotate around the screw shaft 7. On the other hand, the ball nut 6 is connected to the conductive member 5. Therefore, when the ball nut 6 rotates, the conductive member 5 rotates. Even in such a configuration, as described above, since the first permanent magnet 3 and the second permanent magnet 4 integral with the magnet holding member 2 rotate relative to the conductive member 5, an eddy current is generated in the conductive member 5 Occurs. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

  Referring to FIG. 10, in the present embodiment, the inner end face 6 b of the flange 6 a of the ball nut 6 faces one end face 5 a of the conductive member 5. A heat insulating member 12 is provided between the inner end surface 6 b of the flange 6 a of the ball nut 6 and the end surface 5 a of the conductive member 5. In a state in which the heat insulating member 12 is sandwiched between the inner end surface 6b of the flange 6a of the ball nut 6 and the end surface 5a of the conductive member 5, the flange 6a of the ball nut 6 is fixed to the conductive member 5 by a bolt (not shown). Ru. That is, the heat insulating member 12 is provided at the attachment portion between the ball nut 6 and the conductive member 5.

  According to the eddy current damper 1 of the present embodiment, the heat conduction from the conductive member 5 to the ball nut 6 is blocked by the heat insulating member 12 provided at the attachment portion between the ball nut 6 and the conductive member 5. That is, the heat insulating member 12 functions as a heat conduction suppressing mechanism. Thereby, the temperature rise of the ball nut 6 is suppressed. Therefore, it is possible to suppress the deterioration of the vibration damping performance and the deterioration of the durability due to the temperature rise of the ball nut 6.

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 5 can accommodate the magnet holding member 2, the ball nut 6, and the screw shaft 7. The first permanent magnet 3 and the second permanent magnet 4 are attached to the outer peripheral surface of the magnet holding member 2. Therefore, the inner circumferential surface of the conductive member 5 faces the first permanent magnet 3 and the second permanent magnet 4 with a gap.

  The fixture 8 a is connected to the magnet holding member 2. Therefore, the magnet holding member 2 does not rotate around the screw shaft 7. On the other hand, the ball nut 6 is connected to the conductive member 5. Therefore, when the ball nut 6 rotates, the conductive member 5 rotates. Even in such a configuration, as described above, since the first permanent magnet 3 and the second permanent magnet 4 integral with the magnet holding member 2 rotate relative to the conductive member 5, an eddy current is generated in the conductive member 5 Occurs. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

  Referring to FIG. 13, in the present embodiment, the heat insulating member 12 is provided between the inner end surface 6b of the flange 6a of the ball nut 6 and the end surface 5a of the conductive member 5 as in the second embodiment. Therefore, according to the eddy current damper 1 of the present embodiment, the temperature rise of the ball nut 6 is suppressed as in the second embodiment. Therefore, it is possible to suppress the deterioration of the vibration damping performance and the deterioration of the durability due to the temperature rise of the ball nut 6.

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 2 can accommodate conductive member 5, ball nut 6 and screw shaft 7. The first permanent magnet 3 and the second permanent magnet 4 are attached to the inner peripheral surface of the magnet holding member 2. Therefore, the outer peripheral surface of the conductive member 5 faces the first permanent magnet 3 and the second permanent magnet 4 with a gap.

  The fixture 8 a shown in FIG. 1 is connected to the conductive member 5. Therefore, the conductive member 5 does not rotate around the screw shaft 7. On the other hand, the ball nut 6 is fixed to the magnet holding member 2. Therefore, when the ball nut 6 rotates, the magnet holding member 2 rotates. Even in such a configuration, as described above, since the first permanent magnet 3 and the second permanent magnet 4 integral with the magnet holding member 2 rotate relative to the conductive member 5, an eddy current is generated in the conductive member 5 Occurs. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

  Referring to FIG. 14, in the present embodiment, the heat insulating member 12 is provided between the inner end surface 6b of the flange 6a of the ball nut 6 and the end surface 2a of the magnet holding member 2 as in the first embodiment. . Therefore, according to the eddy current damper 1 of the present embodiment, the temperature rise of the ball nut 6 is suppressed as in the first embodiment. Therefore, it is possible to suppress the deterioration of the vibration damping performance and the deterioration of the durability due to the temperature rise of the ball nut 6.

  As described above, when the eddy current damper generates a damping force, the temperature of the conductive member rises. The first permanent magnet and the second permanent magnet face the conductive member. Therefore, the temperatures of the first permanent magnet and the second permanent magnet may increase due to radiant heat from the conductive member. If the temperature of the permanent magnet is increased, the magnetic force may be reduced.

  In the eddy current damper of the first embodiment, the conductive member 5 is disposed outside the magnet holding member 2. That is, the conductive member 5 is disposed at the outermost side to be in contact with the outside air. Thereby, the conductive member 5 is cooled by the outside air. Therefore, the temperature rise of the conductive member 5 can be suppressed. As a result, temperature rise of the first permanent magnet and the second permanent magnet can be suppressed.

  In the eddy current damper of the second embodiment, the magnet holding member 2 is disposed outside the conductive member 5. That is, the magnet holding member 2 is disposed at the outermost side to be in contact with the outside air. Thereby, the magnet holding member 2 is cooled by external air. Therefore, the first permanent magnet and the second permanent magnet can be cooled through the magnet holding member 2. As a result, temperature rise of the first permanent magnet and the second permanent magnet can be suppressed.

  In the eddy current damper of the third embodiment, the conductive member 5 is disposed outside the magnet holding member 2. That is, the conductive member 5 is disposed at the outermost side to be in contact with the outside air. In addition, the conductive member 5 rotates around the screw shaft 7. Thus, the rotating conductive member 5 is efficiently cooled by the outside air. Therefore, the temperature rise of the conductive member 5 can be suppressed. As a result, temperature rise of the first permanent magnet and the second permanent magnet can be suppressed.

  In the eddy current damper of the fourth embodiment, the magnet holding member 2 is disposed outside the conductive member 5. That is, the magnet holding member 2 is disposed at the outermost side to be in contact with the outside air. In addition, the magnet holding member 2 rotates around the screw shaft 7. Thereby, the rotating magnet holding member 2 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 2. As a result, the temperature rise of the first permanent magnet 3 and the second permanent magnet 4 can be suppressed.

Fifth Embodiment
The eddy current damper of the fifth embodiment is a modification of the eddy current damper of the first embodiment described above.

  FIG. 15 is a cross-sectional view of a surface of the eddy current damper of the fifth embodiment along the axial direction. Referring to FIG. 15, in the present embodiment, a recessed portion 13 is formed on the end surface 2 a of the magnet holding member 2 opposed to the inner end surface 6 b of the flange 6 a of the ball nut 6. The recess 13 is a groove along the circumferential direction around the screw shaft 7. On the other hand, the inner end surface 6b of the flange 6a of the ball nut 6 is a flat surface without a recess. With the inner end face 6b of the flange 6a of the ball nut 6 in contact with the end face 2a of the magnet holding member 2, the flange 6a of the ball nut 6 is fixed to the magnet holding member 2 by a bolt (not shown). That is, the recess 13 is formed in the mounting portion between the ball nut 6 and the magnet holding member 2.

  According to the eddy current damper 1 of the present embodiment, the contact area between the magnet holding member 2 and the ball nut 6 is small due to the recess 13 formed in the mounting portion between the ball nut 6 and the magnet holding member 2. Therefore, heat conduction from the magnet holding member 2 to the ball nut 6 is suppressed. That is, the recess 13 functions as a heat conduction suppressing mechanism. Thereby, the temperature rise of the ball nut 6 is suppressed. Therefore, it is possible to suppress a decrease in vibration damping performance and a decrease in durability due to the temperature rise of the ball nut 6.

Sixth Embodiment
The eddy current damper of the sixth embodiment is a modification of the above-described eddy current damper of the second embodiment.

  FIG. 16 is a cross-sectional view of a surface of the eddy current damper of the sixth embodiment along the axial direction. Referring to FIG. 16, in the present embodiment, a recess 13 is formed on the end surface 5 a of the conductive member 5 opposed to the inner end surface 6 b of the flange 6 a of the ball nut 6. The recess 13 is a groove along the circumferential direction around the screw shaft 7. On the other hand, the inner end surface 6b of the flange 6a of the ball nut 6 is a flat surface without a recess. With the inner end face 6b of the flange 6a of the ball nut 6 in contact with the end face 5a of the conductive member 5, the flange 6a of the ball nut 6 is fixed to the conductive member 5 by a bolt (not shown). That is, the recessed portion 13 is formed in the mounting portion between the ball nut 6 and the conductive member 5.

  According to the eddy current damper 1 of the present embodiment, the contact area between the conductive member 5 and the ball nut 6 is small due to the recess 13 formed in the attachment portion between the ball nut 6 and the conductive member 5. Therefore, heat conduction from the conductive member 5 to the ball nut 6 is suppressed. That is, the recess 13 functions as a heat conduction suppressing mechanism. Thereby, the temperature rise of the ball nut 6 is suppressed. Therefore, it is possible to suppress the deterioration of the vibration damping performance and the deterioration of the durability due to the temperature rise of the ball nut 6.

Seventh Embodiment
The eddy current damper of the seventh embodiment is a modification of the above-described eddy current damper of the third embodiment.

  FIG. 17 is a cross-sectional view of a surface of the eddy current damper of the seventh embodiment taken along the axial direction. Referring to FIG. 17, in the present embodiment, as in the sixth embodiment described above, the recess 13 is formed on the end surface 5a of the conductive member 5 opposed to the inner end surface 6b of the flange 6a of the ball nut 6. Therefore, according to the eddy current damper 1 of the present embodiment, the temperature rise of the ball nut 6 is suppressed as in the above-described sixth embodiment. Therefore, it is possible to suppress a decrease in vibration damping performance and a decrease in durability due to the temperature rise of the ball nut 6.

Eighth Embodiment
The eddy current damper of the eighth embodiment is a modification of the above-described eddy current damper of the fourth embodiment.

  FIG. 18 is a cross-sectional view of a surface of the eddy current damper of the eighth embodiment taken along the axial direction. Referring to FIG. 18, in the present embodiment, the recess 13 is formed on the end face 2a of the magnet holding member 2 opposed to the inner end face 6b of the flange 6a of the ball nut 6 as in the fifth embodiment. . Therefore, according to the eddy current damper 1 of the present embodiment, the temperature rise of the ball nut 6 is suppressed as in the fifth embodiment. Therefore, it is possible to suppress the deterioration of the vibration damping performance and the deterioration of the durability due to the temperature rise of the ball nut 6.

[Ninth embodiment]
The eddy current damper of the ninth embodiment is a modification of the above-described eddy current damper of the fifth embodiment.

  FIG. 19 is a cross-sectional view of a surface of the eddy current damper of the ninth embodiment taken along the axial direction. Referring to FIG. 19, in the present embodiment, a recess 14 is formed on the inner end surface 6 b of the flange 6 a of the ball nut 6 facing the end surface 2 a of the magnet holding member 2. The recess 14 is a groove along the circumferential direction around the screw shaft 7. On the other hand, the end face 2a of the magnet holding member 2 is a flat surface without a recess. However, the recess 13 may be formed on the end face 2 a of the magnet holding member 2. With the inner end face 6b of the flange 6a of the ball nut 6 in contact with the end face 2a of the magnet holding member 2, the flange 6a of the ball nut 6 is fixed to the magnet holding member 2 by a bolt (not shown). That is, the recess 14 is formed in the mounting portion between the ball nut 6 and the magnet holding member 2.

  According to the eddy current damper 1 of the present embodiment, the magnet holding member 2 and the ball nut are formed by the concave portion 14 formed in the mounting portion between the ball nut 6 and the magnet holding member 2 as in the fifth embodiment described above. The contact area with 6 is small. Therefore, heat conduction from the magnet holding member 2 to the ball nut 6 is suppressed. That is, the recess 14 functions as a heat conduction suppressing mechanism. Thereby, the temperature rise of the ball nut 6 is suppressed. Therefore, it is possible to suppress the deterioration of the vibration damping performance and the deterioration of the durability due to the temperature rise of the ball nut 6.

  The recess 14 of the ninth embodiment can also be applied to the above-described eddy current damper of the sixth to eighth embodiments. When applying the recess 14 to the above-described eddy current damper of the sixth and seventh embodiments, the end face 5 a of the conductive member 5 is a flat surface without a recess. However, the recess 13 may be formed on the end face 5 a of the conductive member 5. In the case where the recess 14 is applied to the above-described eddy current damper of the eighth embodiment, the end face 2a of the magnet holding member 2 is a flat surface without a recess. However, the recess 13 may be formed on the end face 2 a of the magnet holding member 2.

  The heat insulating member 12 of the first to fourth embodiments can also be applied to the eddy current dampers of the fifth to ninth embodiments including the recess 13 and / or the recess 14.

  The eddy current damper of the present embodiment has been described above. Since the eddy current is generated by the change of the magnetic flux passing through the conductive member 5, the first permanent magnet 3 and the second permanent magnet 4 may rotate relative to the conductive member 5. Further, as long as the conductive member 5 is present in the magnetic field generated by the first permanent magnet 3 and the second permanent magnet 4, the positional relationship between the conductive member and the magnet holding member is not particularly limited.

  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: Magnet holding member 3: First permanent magnet 4: Second permanent magnet 5: Conductive member 6: Ball nut 7: Screw shaft 8a, 8b: Fittings 9: Radial bearing 10: Thrust bearing 11 : Pole piece 12: heat insulating member 13, 14: recess

Claims (3)

Screw shaft,
A plurality of first permanent magnets arranged circumferentially around the screw shaft;
A plurality of second permanent magnets disposed between the first permanent magnets, wherein the arrangement of the first permanent magnet and the magnetic pole is reversed;
A cylindrical magnet holding member for holding the first permanent magnet and the second permanent magnet;
A cylindrical conductive member having conductivity and facing the first permanent magnet and the second permanent magnet with a gap in between;
A ball nut fixed to the magnet holding member or the conductive member and engaged with the screw shaft;
When the ball nut is fixed to the magnet holding member, the ball nut and the magnet holding member are provided at the attachment portion, and when the ball nut is fixed to the conductive member, the ball nut and the conductive member An eddy current damper comprising a heat conduction suppressing mechanism provided at a mounting portion of An eddy current damper according to claim 1, wherein
When the ball nut is fixed to the magnet holding member, the heat conduction suppressing mechanism includes a heat insulating member provided between the mounting surface of the ball nut and the mounting surface of the magnet holding member,
When the said ball nut is fixed to the said electrically conductive member, the said heat conduction suppression mechanism contains the heat insulation member provided between the attachment surface of the said ball nut, and the attached surface of the said electrically conductive member, The eddy current type damper. An eddy current damper according to claim 1 or 2, wherein
When the ball nut is fixed to the magnet holding member, the heat conduction suppressing mechanism includes a recess formed on at least one of the mounting surface of the ball nut and the mounting surface of the magnet holding member.
When the ball nut is fixed to the conductive member, the heat conduction suppressing mechanism includes an eddy current damper including a recess formed in at least one of the mounting surface of the ball nut and the mounting surface of the conductive member. .

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