JP7256388B2 - Eddy current damper - Google Patents

Description

The present disclosure relates to eddy current dampers.

A damping device is known as a mechanism for protecting a building from vibrations caused by an earthquake or the like. A damping device is attached, for example, so as to connect pillars and beams in a building, and attenuates vibrations input to the building.

For example, Patent Literature 1 discloses a fluid damper, which is a type of vibration damping device. In this fluid damper, a viscous body or the like is enclosed in a chamber defined by a rotating inner cylinder that rotates in synchronization with vibration and a fixed outer cylinder that accommodates the rotating inner cylinder. When vibration is transmitted to the fluid damper, the kinetic energy of the vibration causes the rotation inner cylinder to rotate, and a shearing force acts on the viscous body or the like in the chamber. As a result, the viscous body or the like generates heat, kinetic energy is converted into thermal energy, and vibration is damped.

For example, Patent Literature 2 discloses an eddy current damper, which is a different type of damping device from the fluid damper. In this eddy-current damper, a plurality of permanent magnets are arranged along the circumferential direction on the outer peripheral surface of a cylindrical stator, and a conductive circular tube is opposed to the permanent magnets. When vibration is transmitted to the eddy current damper, the permanent magnet and the conductor tube rotate relative to each other, and the conductor tube moves within the magnetic field formed by the permanent magnet. Eddy currents are generated in the conductor tube as it moves within the magnetic field. This eddy current creates a new magnetic field that opposes the magnetic field of the permanent magnets, thereby damping the vibration.

Japanese Patent No. 3408706 Japanese Patent No. 6294502

By the way, when a hydrodynamic damper or an eddy current damper is shipped as a product, a test for measuring the damping force is performed to check whether the damping force is within a predetermined range around a reference value. If the measured damping force is out of the predetermined range, work is performed to adjust the damping force. In the fluid damper exemplified in Patent Document 1, for example, the damping force is adjusted by adjusting the pressure inside the chamber.

On the other hand, in the eddy current damper exemplified in Patent Document 2, the number of permanent magnets contributes to the damping force. . Even if the eddy-current damper could be disassembled, it would be difficult to attach a new permanent magnet due to attraction and repulsion with the already attached permanent magnet. Moreover, since the permanent magnets are fixed with an adhesive or the like, it is difficult to remove the permanent magnets that have already been attached. In addition, the distance between the damping ring (conductor circular tube in Patent Document 2) where eddy currents are generated and the permanent magnet also contributes to the damping force. etc. are required, which is not realistic. For these reasons, it is not easy to adjust the damping force of the eddy current damper at the time of product shipment.

An object of the present disclosure is to provide an eddy current damper that can easily adjust damping force.

An eddy current damper according to the present disclosure includes a magnet retaining ring, a plurality of permanent magnets, and a damping ring. A plurality of permanent magnets are fixed to the magnet retaining ring and arranged along the circumferential direction of the magnet retaining ring. A damping ring is arranged coaxially with the magnet retaining ring so as to face the plurality of permanent magnets with a gap therebetween. The damping ring rotates relative to the magnet retaining ring and is electrically conductive. Of the magnet retaining ring and the braking ring, the radially outer ring includes a plurality of holes opening to the outer peripheral surface, and an adjustment material inserted into each of the holes.

According to the eddy current damper according to the present disclosure, it is possible to easily adjust the damping force.

FIG. 1 is a longitudinal sectional view of an eddy current damper according to the first embodiment. FIG. 2 is a partially enlarged cross-sectional view of the eddy current damper. 3 is an enlarged view of FIG. 2. FIG. FIG. 4 is a schematic diagram showing the positional relationship between the holes and the permanent magnets. FIG. 5 is a schematic diagram showing magnetic flux from a permanent magnet in a cross-sectional view. FIG. 6 is a schematic diagram showing the magnetic flux from the permanent magnet as seen from the outside of the braking ring. FIG. 7 is a partial enlarged cross-sectional view of an eddy current damper in which an adjustment member shorter than that of FIG. 3 is inserted. FIG. 8 is a diagram for explaining a method of inserting the adjustment member and set screw into the hole. FIG. 9 is a diagram for explaining a method of inserting the adjustment member and set screw into the hole. FIG. 10 is a diagram for explaining a method of inserting the adjusting material and set screw into the hole. FIG. 11 is a diagram for explaining a method of inserting the adjustment member and set screw into the hole. FIG. 12 is a partial enlarged view of a longitudinal section of the eddy current damper according to the second embodiment. FIG. 13 is a partially enlarged cross-sectional view of the eddy current damper. FIG. 14 is a schematic diagram showing the positional relationship between the holes and the permanent magnets.

An eddy current damper according to an embodiment includes a magnet retaining ring, a plurality of permanent magnets, and a damping ring. A plurality of permanent magnets are fixed to the magnet retaining ring and arranged along the circumferential direction of the magnet retaining ring. A damping ring is arranged coaxially with the magnet retaining ring so as to face the plurality of permanent magnets with a gap therebetween. The damping ring rotates relative to the magnet retaining ring and is electrically conductive. Of the magnet retaining ring and the braking ring, the ring disposed radially outward includes a plurality of holes opening on the outer peripheral surface and an adjusting member inserted into each of the holes (first configuration ).

In the eddy current damper according to the first configuration, the damping force is reduced in advance by providing a hole in the magnet holding ring or the braking ring, and the damping force is adjusted by inserting an adjusting material into the hole. That is, when the hole is a mere space, the magnetic flux from the permanent magnet flows so as to bypass the hole, and the magnetic resistance increases, so the damping force of the eddy current damper decreases. On the other hand, when the adjustment material is inserted into the hole, the magnetic flux from the permanent magnet passes through the adjustment material in the hole, and the magnetic resistance becomes lower, so the attenuation of the eddy current damper is greater than when the hole is a mere space. power can be increased. The hole opens to the outer peripheral surface of the magnet retaining ring or the braking ring, whichever is arranged on the outer side. Therefore, even after the eddy current damper is assembled, the adjustment material can be inserted into the hole from the outside. Therefore, the damping force of the eddy current damper can be easily adjusted.

In the eddy current damper according to the first configuration, each of the holes may radially pass through the outer ring (second configuration).

In the eddy current damper according to the second configuration, since the hole is a through hole, it is not necessary to control the depth when forming the hole in the magnet holding ring or the braking ring. Therefore, the eddy current damper can be easily manufactured.

In the eddy current damper according to the first or second configuration, the adjustment material includes an adjustment material body, and a set screw disposed radially outside the adjustment material body and tightened into the hole. (third configuration).

In the eddy current damper according to the third configuration, since the set screw is provided on the outside of the adjustment material body, it is possible to suppress the adjustment material body from slipping out of the hole.

In the eddy current damper according to any one of the first to third configurations, it is preferable that the damping ring be arranged radially outside the magnet retaining ring (fourth configuration).

In the eddy current damper according to the fourth configuration, each hole preferably faces a magnet row composed of a plurality of permanent magnets (fifth configuration).

Magnetic flux emitted from the north pole of one permanent magnet passes through the damping ring and reaches the south pole of an adjacent permanent magnet. Since the magnetic flux tries to pass through the shortest path, it tends to flow at a high density through the portion of the braking ring that faces the magnet array. In the eddy current damper according to the fifth configuration, a hole is provided in a portion of the braking ring that faces the magnet array, and the magnetic flux does not flow in the shortest path. The force can be significantly reduced. Therefore, a large adjustment range of the damping force can be obtained.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same reference numerals are given to the same or corresponding parts in the drawings, and the description thereof will not be repeated.

<First embodiment>
[Configuration of eddy current damper 1]
FIG. 1 is a longitudinal sectional view of an eddy current damper 1 according to the first embodiment. A longitudinal section refers to a section along the central axis X of the eddy current damper 1 . A cross section perpendicular to the central axis X of the eddy current damper 1 is a cross section. An eddy current damper 1 is attached to a building. The eddy current damper 1 is fixed to a pillar or beam of a building via mounting members 16A and 16B.

The eddy current damper 1 includes a screw shaft 11 , a ball nut 12 , a magnet retaining ring 13 , a plurality of permanent magnets 14 and a damping ring 15 .

(Screw shaft 11)
The screw shaft 11 is rod-shaped and has a threaded portion on its outer peripheral surface. The screw shaft 11 extends along the central axis X. As shown in FIG. One end of the screw shaft 11 is connected to the mounting member 16A. The other end of the screw shaft 11 is a free end. The screw shaft 11 passes through the ball nut 12 .

(Ball nut 12)
The ball nut 12 is generally hat-shaped. Ball nut 12 includes a cylindrical portion 121 and a flange portion 122 . A spiral groove corresponding to the threaded portion of the screw shaft 11 is formed on the inner peripheral surface of the cylindrical portion 121 . A plurality of balls are arranged in the spiral groove, and these balls roll between the spiral groove and the threaded portion of the screw shaft 11 . That is, the ball nut 12 constitutes a ball screw together with the screw shaft 11 .

(Magnet retaining ring 13)
The magnet retaining ring 13 has a substantially cylindrical shape with the central axis X as the axis. One of both ends of the magnet retaining ring 13 is fixed to the support member 131 and the other is fixed to the support member 132 . The support member 131 is fixed to the flange portion 122 of the ball nut 12 with bolts or the like. The magnet retaining ring 13 is thereby attached to the ball nut 12 .

Although the material of the magnet retaining ring 13 is not particularly limited, it is preferably a material with high magnetic permeability. Materials with high magnetic permeability are, for example, carbon steel, cast iron, and the like. The magnet retaining ring 13 may be composed of a plurality of rings connected in the direction in which the central axis X extends (axial direction), or may be a single ring.

(Permanent magnet 14)
A plurality of permanent magnets 14 are held by a magnet holding ring 13 . The permanent magnets 14 are arranged along the circumferential direction of the magnet retaining ring 13 to form a magnet row. A permanent magnet 14 is fixed to the outer peripheral surface of the magnet retaining ring 13 . Each of the permanent magnets 14 is fixed to the magnet retaining ring 13 by, for example, adhesive, screws, or the like. In the example of this embodiment, the magnet retaining ring 13 is provided with one magnet row. However, the magnet retaining ring 13 may be provided with two or more magnet rows.

The orientation of the magnetic poles of each permanent magnet 14 is along the radial direction of the magnet retaining ring 13 . That is, in each permanent magnet 14, one magnetic pole of the N pole and the S pole is arranged radially outward, and the other magnetic pole is arranged radially inward. The orientation of the magnetic poles of each permanent magnet 14 is opposite to the orientation of the magnetic poles of adjacent permanent magnets 14 in the circumferential direction of the magnet retaining ring 13 . That is, the permanent magnets 14 are arranged with their magnetic pole directions alternately reversed along the circumferential direction of the magnet retaining ring 13 . Each permanent magnet 14 may be arranged in contact with the adjacent permanent magnet 14, or may be arranged with a gap between them. When a gap is provided between adjacent permanent magnets 14 , the permanent magnets 14 are preferably arranged at regular intervals over the entire circumference of the magnet retaining ring 13 .

(braking ring 15)
The braking ring 15, like the magnet retaining ring 13, has a substantially cylindrical shape with the central axis X as its axis. That is, the braking ring 15 is arranged coaxially with the magnet retaining ring 13 . The damping ring 15 is arranged radially outside the magnet retaining ring 13 . The inner peripheral surface of the braking ring 15 faces the permanent magnet 14 with a small gap in the radial direction. One end of the braking ring 15 is fixed to the support member 151 with a bolt or the like. The other end of the braking ring 15 is fixed to the support member 152 with bolts or the like. The support members 151 and 152 that support the braking ring 15 are arranged on the outer peripheral sides of the support members 131 and 132 that support the magnet retaining ring 13, respectively. A radial bearing 19A and a thrust bearing 19B are arranged between the support members 151 and 152 and the support members 131 and 132, respectively. The radial bearing 19A and the thrust bearing 19B allow relative rotation between the support members 151, 152 and the support members 131, 132. Therefore, the braking ring 15 and the magnet retaining ring 13 can rotate about the central axis X relatively.

The braking ring 15 is electrically conductive. The damping ring 15 may be magnetic or non-magnetic. For example, the material of the braking ring 15 may be a conductive ferromagnetic material such as carbon steel or cast iron, or may be a conductive weak magnetic material such as ferritic stainless steel. The material of the braking ring 15 may be, for example, a non-magnetic material such as aluminum alloy, austenitic stainless steel, or copper alloy.

[Operation of eddy current damper 1]
When vibration is input to the eddy current damper 1 having such a configuration, the screw shaft 11 moves in the axial direction, and the ball nut 12, the magnet retaining ring 13 and the permanent magnet 14 rotate accordingly. When the permanent magnet 14 rotates, the braking ring 15 relatively moves within the magnetic field of the permanent magnet 14 , and an eddy current is generated in the braking ring 15 . The generation of the eddy current causes the Lorentz force to act on the braking ring 15, and as a reaction thereto, force acts on the permanent magnet 14 in the direction opposite to the direction of rotation. As a result, the rotation of the magnet retaining ring 13 that retains the permanent magnet 14 and the ball nut 12 to which the magnet retaining ring 13 is attached is braked, and the movement of the screw shaft 11 is suppressed. Therefore, vibration can be damped.

[Details of braking ring 15]
The braking ring 15 will be described in more detail with reference to FIG. FIG. 2 is a partially enlarged cross-sectional view of the eddy current damper 1. As shown in FIG. The damping ring 15 includes a plurality of holes 153 and a plurality of adjusters 154 .

The plurality of holes 153 are arranged in the circumferential direction of the braking ring 15 . The hole 153 is arranged in the braking ring 15 so that the braking ring 15 has a symmetrical shape with respect to a plane containing the central axis X. As shown in FIG. In the example of this embodiment, the holes 153 are arranged at regular intervals in the circumferential direction of the braking ring 15 . However, the holes 153 do not necessarily have to be arranged at regular intervals.

Each of the holes 153 opens to the outer peripheral surface 156 of the braking ring 15 . Each of the holes 153 extends radially through the braking ring 15 . However, the hole portion 153 may not be a through hole. For example, the hole 153 may be provided to a predetermined depth from the outer peripheral surface 156 of the braking ring 15 and may not open to the inner peripheral surface 157 of the braking ring 15 . An adjustment member 154 is inserted into each of the holes 153 .

The configuration of the hole portion 153 and the adjustment member 154 will be described in more detail with reference to FIG. 3 . 3 is an enlarged view of FIG. 2. FIG. However, in FIG. 3, for convenience of explanation, the permanent magnet 14 is moved from the state shown in FIG. Hole 153 includes a threaded portion 153A and a tapered portion 153B. The threaded portion 153A is provided from the outer peripheral surface 156 of the braking ring 15 to a predetermined depth. A spiral thread groove is formed on the wall surface of the threaded portion 153A. The tapered portion 153B is provided from the inner peripheral surface 157 of the braking ring 15 to the threaded portion 153A. The tapered portion 153B tapers radially inward. The tapered portion 153B is a truncated conical space. The cross-sectional shapes of the threaded portion 153A and tapered portion 153B are typically circular, but may be elliptical, polygonal, or the like.

The adjustment material 154 includes an adjustment material body 1541 and a set screw 1542 .

The adjusting material body 1541 is inserted into the tapered portion 153B. The adjustment material main body 1541 has substantially the same shape as the tapered portion 153B. For example, when the tapered portion 153B is a truncated cone-shaped space, the adjustment material main body 1541 has a truncated cone shape. The volume of the adjustment material main body 1541 is slightly smaller than the volume of the tapered portion 153B. However, the volume of the adjustment material main body 1541 may be the same as or slightly larger than the volume of the tapered portion 153B. The adjusting material main body 1541 is arranged so as not to protrude radially inward from the inner peripheral surface 157 of the braking ring 15 . That is, the inner surface 1541A of the adjusting material main body 1541 is arranged on the same plane as the inner peripheral surface 157 of the braking ring 15 or arranged at a position recessed from the inner peripheral surface 157 . The adjusting material main body 1541 has a bolt hole 1541B.

The material of the adjustment material main body 1541 is not particularly limited. The adjustment material main body 1541 may or may not have conductivity. The adjustment material main body 1541 may be magnetic or non-magnetic. However, the adjustment material main body 1541 has at least one of the properties of conductivity and magnetism. The surface hardness of the adjustment material main body 1541 is preferably smaller than the hardness of the wall surface of the hole 153 .

The set screw 1542 has a shape corresponding to the threaded portion 153A. A set screw 1542 is tightened onto the threaded portion 153A. The set screw 1542 is arranged radially outside the adjustment body 1541 of the damping ring 15 . Set screw 1542 is preferably in contact with adjustment material body 1541 to fix the position of adjustment material body 1541 . The setscrew 1542 has a hexagon hole or a cross hole on the screw head.

FIG. 4 is a schematic diagram showing the positional relationship between the hole 153 and the permanent magnet 14. As shown in FIG. FIG. 4 is a diagram of the braking ring 15 viewed from the outside. Each hole 153 faces a magnet array 141 composed of a plurality of permanent magnets 14 in the radial direction of the braking ring 15 . Therefore, while the brake ring 15 and the permanent magnets 14 make one relative rotation, the holes 153 sequentially overlap all the permanent magnets 14 when viewed in the radial direction of the brake ring 15 . In other words, the hole 153 is arranged within the range of the width (length in the axial direction) of the magnet array 141 indicated by the chain double-dashed line in FIG. Preferably, hole 153 is provided at the center of magnet row 141 in the width direction.

[effect]
In the eddy current damper 1 according to the first embodiment, the brake ring 15 is provided with the hole 153, and the adjusting material 154 is inserted into the hole 153. As shown in FIG. Thereby, the damping force of the eddy current damper 1 can be adjusted. This point will be specifically described with reference to FIGS. 5 and 6. FIG.

FIG. 5 is a schematic diagram showing the magnetic flux 14A from the permanent magnet 14 in cross section. Referring to FIG. 5, magnetic flux 14A emitted from the N pole of a certain permanent magnet 14 passes through braking ring 15 and tries to reach the S pole of the adjacent permanent magnet 14 through the shortest route. However, when the hole 153 is provided on the shortest path of the magnetic flux 14A, the magnetic flux 14A flows through the braking ring 15 so as to bypass the hole 153 as indicated by the broken line in FIG. growing. Also, eddy currents cannot flow through the holes 153 . Therefore, the Lorentz force acting on the braking ring 15 is reduced. Along with this, the force that hinders the rotation of the permanent magnet 14 is also reduced, and the damping force of the eddy current damper 1 is reduced.

However, when the adjustment material 154 (adjustment material main body 1541) is inserted into the hole 153, the adjustment material main body 1541 allows the magnetic flux 14A to pass through the shortest path as indicated by the solid line arrow in FIG. As a result, the reduced Lorentz force and the force that inhibits the rotation of the permanent magnet 14 can be increased, and the damping force can be recovered. The degree of recovery of the damping force can be adjusted by appropriately setting the material, dimensions, etc. of the adjustment material main body 1541 .

A case in which the damping force is adjusted by the material of the adjustment material main body 1541 will be described in detail. When the adjustment material main body 1541 is made of a magnetic material, the magnetic flux 14A can easily pass through the hole 153, and the damping force can be recovered to a relatively large extent. If the adjustment material main body 1541 is made of a non-magnetic material, the magnetic flux 14A does not pass through the hole 153 so much, so the degree of recovery of the damping force is reduced.

A case in which the damping force is adjusted by the dimensions of the adjustment material main body 1541 will be described in detail. As described above, in the magnetic circuit formed by the adjacent permanent magnets 14, the magnetic flux 14A tries to pass through the shortest path. That is, the magnetic flux 14A tends to flow through the surface (the inner peripheral surface 157) of the braking ring 15 facing the permanent magnet 14 and its vicinity. For example, as shown in FIG. 3, when the inner surface 1541A of the adjustment material main body 1541 is aligned with the inner peripheral surface 157 of the braking ring 15, the magnetic flux 14A easily passes through the braking ring 15 in the shortest route, and the damping force is compared. can be significantly recovered. On the other hand, as shown in FIG. 7, the length of the adjusting material main body 1541 in the radial direction of the braking ring 15 is shortened, and the inner surface 1541A of the adjusting material main body 1541 is positioned outside the inner peripheral surface 157 of the braking ring 15. do. In this case, since the distance from one permanent magnet 14 to the other permanent magnet 14 becomes longer for the magnetic flux 14A to reach the other permanent magnet 14, the degree of recovery of the damping force becomes smaller. The damping force decreases as the gap between the permanent magnet 14 and the inner surface 1541A of the adjustment material main body 1541 increases.

Thus, according to the eddy current damper 1 according to the first embodiment, the damping force can be adjusted by the adjustment material 154 inserted into the hole 153 . Moreover, the hole 153 opens to the outer peripheral surface 156 of the braking ring 15 that is arranged outside the magnet holding ring 13 . Therefore, the damping force of the eddy current damper 1 can be easily adjusted even after the eddy current damper 1 has been assembled, such as when the product is shipped.

8 to 11 are diagrams for explaining a specific procedure for inserting the adjustment material 154 into the hole 153. FIG. Referring to FIG. 8, first, eddy current damper 1 assembled with parts other than adjustment member 154 is prepared. The braking ring 15 of the eddy-current damper 1 is pre-drilled with a hole 153 by a drill or the like. In order to insert the adjusting material body 1541 into the hole 153 , the bolt 100 is attached to the bolt hole 1541 B of the adjusting material body 1541 . Next, as shown in FIG. 9, the adjustment material main body 1541 is placed on the tapered portion 153B, and the bolt 100 is hit with a tool such as a hammer to insert the adjustment material main body 1541 to a predetermined position. After that, as shown in FIG. 10, the bolt 100 is removed from the adjusting material main body 1541 .

Subsequently, as shown in FIG. 11, a set screw 1542 is inserted into the hole 153 . For example, a tool such as a screwdriver is attached to the hexagonal hole or cross hole of the set screw 1542, and the set screw 1542 is tightened into the screw portion 153A while rotating the tool. The tool is then removed from set screw 1542 . This completes the insertion of the adjustment member 154 into the hole 153 . The adjusting material 154 is determined in material and size so that the damping force of the eddy current damper 1 is within a predetermined range.

As described above, in the eddy current damper 1 according to the first embodiment, the adjustment material 154 can be attached and detached from the outside. can be adjusted.

The hole 153 can be formed by machining from the outer peripheral surface 156 side of the braking ring 15 . In the eddy current damper 1 according to the first embodiment, the hole 153 penetrates the braking ring 15 in the radial direction. Therefore, when forming the hole 153, it is not necessary to consider the depth of the hole 153, and the hole 153 can be formed easily.

In the eddy current damper 1 according to the first embodiment, the tapered portion 153B of the hole portion 153 into which the adjustment material main body 1541 is inserted tapers inward in the radial direction of the braking ring 15 . Therefore, the adjustment material main body 1541 can be easily attached and detached, and the damping force can be easily adjusted. In addition, it is possible to prevent the adjusting material main body 1541 from coming out inside the braking ring 15 . A set screw 1542 is arranged on the outside of the adjusting material body 1541 . This setscrew 1542 can also prevent the adjuster body 1541 from slipping out of the brake ring 15 . Furthermore, by fixing the position of the adjustment material main body 1541 by the set screw 1542 and the tapered portion 153B of the hole 153, the position of the adjustment material main body 1541 is difficult to change, and the damping force can be stabilized.

Magnetic flux 14A from permanent magnet 14 tries to pass through the shortest path as described above. Therefore, in the braking ring 15 , the magnetic flux 14A concentrates on the portion facing the magnet array 141 . In the eddy current damper 1 according to the first embodiment, a hole 153 is provided in a portion of the braking ring 15 that faces the magnet row 141 . Therefore, the damping force before the adjustment material 154 is inserted can be greatly reduced. Therefore, the adjustment width of the damping force by the adjusting member 154 can be increased.

In the eddy current damper 1 according to the first embodiment, the surface hardness of the adjustment material main body 1541 can be made smaller than the hardness of the wall surface of the hole 153 , that is, the hardness of the braking ring 15 . In this case, when the adjustment material main body 1541 is inserted into the hole 153, the adjustment material main body 1541 is elastically deformed, and the adhesion between the adjustment material main body 1541 and the hole 153 can be enhanced. This makes it easier for the magnetic flux 14A to pass through the hole 153 into which the adjusting material 154 is inserted, and the damping force can be increased. However, the surface hardness of the adjustment material main body 1541 may be greater than or equal to the hardness of the wall surface of the hole 153 .

<Second embodiment>
FIG. 12 is a partial enlarged view of the longitudinal section of the eddy current damper 2 according to the second embodiment. The eddy current damper 2 differs from the eddy current damper 1 according to the first embodiment in the arrangement of the magnet retaining ring 13, the braking ring 15, and the holes 153. FIG.

As shown in FIG. 12, one end of magnet retaining ring 13 is fixed to support member 151 . One end of the braking ring 15 is fixed to the support member 131 . The damping ring 15 is arranged radially inside the magnet retaining ring 13 and coaxial with the magnet retaining ring 13 . That is, in the eddy current damper 2, the radial positional relationship between the magnet retaining ring 13 and the braking ring 15 is opposite to that of the eddy current damper 1 according to the first embodiment.

The permanent magnet 14 is fixed to the inner peripheral surface of the magnet holding ring 13 and faces the outer peripheral surface of the braking ring 15 with a small gap therebetween. When vibration is input to the eddy current damper 2 having such a configuration, the damping ring 15 rotates and moves within the magnetic field generated by the permanent magnet 14 .

FIG. 13 is a partially enlarged cross-sectional view of the eddy current damper 2. As shown in FIG. A hole 153 is provided in the magnet retaining ring 13 . Although not shown, a plurality of holes 153 are arranged side by side in the circumferential direction of the magnet retaining ring 13 . The hole 153 opens to the outer peripheral surface 133 of the magnet retaining ring 13 . The hole 153 extends radially through the magnet retaining ring 13 . An adjusting material 154 is inserted into the hole 153 .

FIG. 14 is a schematic diagram showing the positional relationship between the hole 153 and the permanent magnet 14. As shown in FIG. FIG. 14 is a view of the magnet retaining ring 13 as seen from the outside. Each of the holes 153 is arranged within the range of the width of the magnet row 141 indicated by the two-dot chain line in FIG. Each of the holes 153 is arranged between adjacent permanent magnets 14 when viewed in the radial direction. Preferably, the hole 153 is arranged at the center of the magnet array 141 in the width direction and between adjacent permanent magnets 14 .

In the second embodiment, the damping force of the eddy-current damper 2 is reduced in advance by providing the magnet holding ring 13 with the holes 153 for bypassing the magnetic flux from the permanent magnets 14 . However, by inserting the adjusting material 154 (adjusting material body 1541) into the hole 153, the magnetic flux from the permanent magnet 14 passes through the hole 153, and the damping force of the eddy current damper 2 is restored. The degree of recovery of the damping force can be adjusted by appropriately setting the material, dimensions, etc. of the adjustment material main body 1541, as in the first embodiment.

Since the hole 153 is open to the outer peripheral surface 133 of the magnet retaining ring 13, the damping force of the eddy current damper 2 can be easily adjusted even after the eddy current damper 2 has been assembled, such as when shipping the product. can do.

Although the embodiments according to the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present disclosure.

In each of the embodiments described above, the adjustment member 154 includes an adjustment member body 1541 and a set screw 1542 . However, the adjustment member 154 may include only the adjustment member main body 1541 or may include only the set screw 1542 . Even if the adjusting member 154 includes only the set screw 1542, the damping force of the eddy current dampers 1 and 2 can be adjusted by appropriately setting the material, size, etc. of the set screw 1542. FIG.

In each of the above embodiments, the orientation of the magnetic poles of the permanent magnets 14 is along the radial direction of the magnet retaining ring 13 . However, the orientation of the magnetic poles of the permanent magnets 14 is not limited to this. The orientation of the magnetic poles of the permanent magnets 14 may be along the circumferential direction of the magnet retaining ring 13 or may be along the central axis X direction.

In each of the embodiments described above, a fixing agent or adhesive may be applied to the threaded portion of the set screw 1542 . Also, in each of the above embodiments, the set screw 1542 may be a tapered screw that tapers radially inward. In these cases, the airtightness in the eddy current dampers 1 and 2 is enhanced, and the entry of foreign matter into the eddy current dampers 1 and 2 can be suppressed.

In each of the above embodiments, the hole portion 153 is provided with a tapered portion 153B as a portion into which the adjusting material main body 1541 is inserted. However, the shape of the hole 153 is not limited to this. The cross-sectional area of the hole 153 may be constant throughout.

In the first embodiment, the magnet retaining ring 13 is fixed to the ball nut 12 and rotates. However, instead of the magnet retaining ring 13, the damping ring 15 may be fixed to the ball nut 12 and rotated. Similarly, in the second embodiment, the magnet retaining ring 13 may be fixed to the ball nut 12 and rotated.

In the second embodiment, the hole 153 penetrates the magnet retaining ring 13 . However, the configuration of the hole 153 is not limited to this. The hole 153 does not have to pass through the magnet retaining ring 13 . In this case, the bottom of the hole 153 exists on the inner peripheral side of the magnet retaining ring 13 . Depending on the thickness of the bottom portion, the magnetic flux from the permanent magnets 14 is concentrated on the bottom portion, and the magnetic flux can efficiently flow between the adjacent permanent magnets 14 . Therefore, the damping force of the eddy current damper 2 can be increased more than when the hole 153 is not provided in the magnet retaining ring 13 . Even when the damping force is increased in advance in this manner, the damping force of the eddy current damper 2 can be changed by inserting the adjustment member 154 into the hole 153 .

1, 2: Eddy current damper 11: Screw shaft 12: Ball nut 13: Magnet retaining ring 133: Outer peripheral surface 14: Permanent magnet 14A: Magnetic flux 141: Magnet row 15: Braking ring 153: Hole 154: Adjusting material 156: Outer peripheral surface 1541: adjustment material main body 1542: set screw

Claims (4)

An eddy current damper,
a magnet retaining ring;
a plurality of permanent magnets fixed to the magnet retaining ring and arranged along the circumferential direction of the magnet retaining ring;
a damping ring disposed coaxially with the magnet retaining ring so as to face the plurality of permanent magnets with a gap therebetween, rotating relative to the magnet retaining ring, and having electrical conductivity;
Of the magnet retaining ring and the braking ring, the ring arranged radially outward is
a plurality of holes opening on the outer peripheral surface;
an adjusting material inserted into each of the holes ,
The adjustment material is
an adjustment material body;
an eddy current damper disposed radially outside the adjustment body and tightened into the hole . The eddy current damper according to claim 1,
An eddy current damper, wherein each of said holes extends through said outer ring in said radial direction. The eddy current damper according to claim 1 or claim 2 ,
An eddy current damper, wherein the damping ring is positioned radially outward of the magnet retaining ring. The eddy current damper according to claim 3 ,
The eddy-current damper, wherein each of the holes faces the magnet row composed of the plurality of permanent magnets.

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