Eddy current damper

Abstract

The eddy current damper (10) of the present invention includes a conductive member (1), a magnet holding member (2), a plurality of permanent magnets (3), and sliding members (91, 92). The magnet holding member (2) is disposed inside the conductive member (1). The permanent magnets (3) are held by the outer peripheral surface of the magnet holding member (2) and are opposite to the inner peripheral surface of the conductive member (1) separated by a gap (G). Protrusions (11, 12, 21, 22) are provided on one or both of the inner peripheral surface of the conductive member (1) and the outer peripheral surface of the magnet holding member (2). When the damper (10) is viewed in cross-section along the central axis, gaps (g1, g2) are formed between the protrusions (11, 12, 21, 22) and the opposite portions. The gaps (g1, g2) between the protrusions (11, 12, 21, 22) and the opposite portions are smaller than the gap (G) between the inner peripheral surface of the conductive member (1) and the permanent magnets (3). The sliding member (91, 92) is disposed in the portion opposite to the protrusion (11, 12, 21, 22), the inner peripheral surface of the conductive member (1), or the outer peripheral surface of the magnet holding member (2).

Description

Technical Field

[0001] This invention relates to an eddy current damper. Background Technology

[0002] Vibration damping devices are used to protect buildings from vibrations caused by earthquakes and other events. These devices are installed, for example, on the columns or beams of a building to suppress its vibrations. One known type of vibration damping device is the eddy current-type damper.

[0003] Patent Document 1 discloses an eddy current damper comprising a cylindrical conductive component, a cylindrical magnet holding component, and a plurality of permanent magnets. In the eddy current damper of Patent Document 1, the magnet holding component is disposed, for example, inside the conductive component. The permanent magnets are held by the magnet holding component and are positioned opposite the conductive component with a gap between them. A ball screw nut is fixed to one axial end of the magnet holding component. The screw shaft of the ball screw passes through the nut and extends into the magnet holding component. The screw shaft and the conductive component are respectively mounted on a column or beam of a building via mounting components.

[0004] When a building vibrates due to an earthquake or other event, and the vibration is input into the eddy current damper of Patent Document 1, the screw shaft of the ball screw moves axially. Simultaneously, the nut and magnet retaining component of the ball screw rotate around the screw shaft. As a result, the permanent magnet held in the magnet retaining component rotates relative to the conductive component, thus generating eddy currents in the conductive component. Through the interaction between these eddy currents and the magnetic field formed by the permanent magnet, a resistance (Lorentz force) is generated in the opposite direction to the rotation of the nut and magnet retaining component, hindering their rotation. Consequently, the axial movement of the screw shaft is also hindered, and the building's vibration is attenuated.

[0005] Patent documents 2 and 3 also disclose an eddy current damper comprising a conductive component, a magnet holding component, and a plurality of permanent magnets. In the eddy current damper of patent document 2, the permanent magnets are disposed within a recess on the outer peripheral surface of the magnet holding component. Heat sinks may also be provided at the axial ends of the outer peripheral surface of the magnet holding component located on both sides of the recess. According to patent document 2, air flows within the eddy current damper as the heat sinks rotate together with the magnet holding component, dissipating heat from the conductive component and the permanent magnets.

[0006] In the eddy current damper of Patent Document 3, a strong magnetic ring is provided on the outer peripheral surface of the magnet holding member. The strong magnetic ring is provided at both ends of the magnet holding member along the axial direction. The strong magnetic ring is positioned opposite the inner peripheral surface of the conductive member with a gap between it and the magnetic field. Patent Document 3 describes that a magnetic circuit formed by the strong magnetic ring is formed near the permanent magnet, and the magnetic field of this magnetic circuit does not face the nut of the ball screw. This prevents leakage of the magnetic field from the magnetic circuit formed by the permanent magnet and prevents the magnetic field from reaching the nut. Therefore, it is possible to prevent the reduction in vibration damping performance caused by leakage of the magnetic field from the magnetic circuit.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: International Publication No. 2019 / 044722

[0010] Patent Document 2: Japanese Patent Application Publication No. 2019-100438

[0011] Patent Document 3: Japanese Patent Application Publication No. 2019-078332

[0012] The problem that the invention aims to solve

[0013] As described in various patent documents, in eddy current dampers using permanent magnets, multiple permanent magnets are positioned opposite conductive components with gaps between them. The smaller these gaps are, the more easily the magnetic field of the permanent magnets can affect the conductive components. Therefore, to increase the resistance of the eddy current damper, it is preferable to minimize the gap between the permanent magnets and the conductive components. However, if the gap between the permanent magnets and the conductive components is reduced, the permanent magnets may come into contact with the conductive components.

[0014] For example, consider the radial oscillation of the nut in a ball screw during rotation, relative to the clearance between the balls rolling in the screw grooves. In this case, the magnet retaining component holding the permanent magnet also oscillates radially along with the nut. When using an eddy current damper, the more the balls wear, the wider the clearance between the balls and the nut becomes, thus increasing the oscillation of the nut during rotation. This oscillation of the nut can potentially create contact between the permanent magnet and a conductive component.

[0015] Alternatively, due to the gaps (wobbling) between the components constituting the eddy current damper, the magnet holding component that holds the permanent magnet may sometimes move radially. Because the magnetic force (attraction) of the permanent magnet acts between the permanent magnet and the conductive component, the permanent magnet and the magnet holding component can easily approach the conductive component. Therefore, contact between the permanent magnet and the conductive component is possible.

[0016] Alternatively, when vibrations from the building are input at an axial angle relative to the screw shaft of the ball screw, the components constituting the eddy current damper may deform or move radially. This can potentially lead to contact between a permanent magnet and a conductive component.

[0017] Thus, through the swinging of the nut, the attraction of the permanent magnet, the direction of the vibration input, or a combination thereof, the permanent magnet may come into contact with the conductive component in the use of eddy current dampers. Contact is particularly likely to occur when the gap between the permanent magnet and the conductive component is too small. In the event of contact, the permanent magnet is at risk of breakage. However, from the viewpoint of increasing the resistance of the eddy current damper, it is necessary to reduce the gap between the permanent magnet and the conductive component. Summary of the Invention

[0018] The objective of this invention is to provide an eddy current damper that can reduce the gap between a permanent magnet and a conductive component while preventing contact between the permanent magnet and the conductive component.

[0019] The eddy current damper of the present invention includes a conductive component, a magnet holding component, a plurality of permanent magnets, and a sliding component. The conductive component is cylindrical. The magnet holding component is disposed inside the conductive component. The magnet holding component is cylindrical. The magnet holding component is configured to rotate about its central axis. The permanent magnets are arranged circumferentially along the magnet holding component. The permanent magnets are held by the outer peripheral surface of the magnet holding component. The permanent magnets are opposed to the inner peripheral surface of the conductive component with a gap. The sliding component has a coefficient of friction smaller than that of the inner peripheral surface of the conductive component and the outer peripheral surface of the magnet holding component. A protrusion is provided on one or both of the inner peripheral surface of the conductive component and the outer peripheral surface of the magnet holding component. The protrusion protrudes radially from the conductive component or the magnet holding component and extends circumferentially. When the eddy current damper is viewed in cross-section along the central axis, a gap is formed between the protrusion and the opposing portion that is radially opposite to the protrusion. When the eddy current damper is viewed in cross-section along the central axis, the gap between the protrusion and the opposing portion is smaller than the gap between the inner peripheral surface of the conductive component and the permanent magnet. A slider may be provided, for example, on the protrusion. Alternatively, a slider may be provided on the inner circumferential surface of the conductive component or the outer circumferential surface of the magnet retaining component, on the portion opposite to the protrusion.

[0020] Invention Effects

[0021] The eddy current damper according to the present invention can reduce the gap between the permanent magnet and the conductive component while preventing contact between the permanent magnet and the conductive component. Attached Figure Description

[0022] Figure 1 This is a longitudinal cross-sectional view of the eddy current damper of the first embodiment.

[0023] Figure 2 This is a cross-sectional view of the eddy current damper of the first embodiment.

[0024] Figure 3 yes Figure 1 A partially enlarged longitudinal section of the eddy current damper shown.

[0025] Figure 4 This is a longitudinal cross-sectional view of the eddy current damper according to the second embodiment, and is an enlarged view showing a portion of the eddy current damper.

[0026] Figure 5 This is a longitudinal cross-sectional view of the eddy current damper according to the third embodiment, and is an enlarged view showing a portion of the eddy current damper.

[0027] Figure 6 This is a longitudinal cross-sectional view of the eddy current damper according to the fourth embodiment, and is an enlarged view showing a portion of the eddy current damper.

[0028] Figure 7 This is a longitudinal cross-sectional view of the eddy current damper according to the fifth embodiment, and is an enlarged view showing a portion of the eddy current damper.

[0029] Figure 8 This is a longitudinal cross-sectional view of a modified example of an eddy current damper according to various embodiments, and is an enlarged view of a portion of the eddy current damper.

[0030] Figure 9 This is a longitudinal cross-sectional view of an eddy current damper, a variation of the various embodiments, and is an enlarged view of a portion of the eddy current damper. Detailed Implementation

[0031] The eddy current damper of this embodiment includes a conductive component, a magnet holding component, multiple permanent magnets, and a sliding component. The conductive component is cylindrical. The magnet holding component is disposed inside the conductive component. The magnet holding component is cylindrical and configured to rotate about its central axis. The permanent magnets are arranged circumferentially along the magnet holding component. The permanent magnets are held by the outer peripheral surface of the magnet holding component. The permanent magnets are opposed to the inner peripheral surface of the conductive component, separated by a gap. The sliding component has a coefficient of friction smaller than that of the inner peripheral surface of the conductive component and the outer peripheral surface of the magnet holding component. A protrusion is provided on one or both of the inner peripheral surface of the conductive component and the outer peripheral surface of the magnet holding component. The protrusion protrudes radially from the conductive component or the magnet holding component and extends circumferentially. When the eddy current damper is viewed in cross-section along the central axis, a gap is formed between the protrusion and its opposing portion in the radial direction. When the eddy current damper is viewed in cross-section along the central axis, the gap between the protrusion and the opposing portion is smaller than the gap between the inner peripheral surface of the conductive component and the permanent magnet. A slider may be provided, for example, on the protrusion. Alternatively, a slider may be provided on the inner circumferential surface of the conductive member or the outer circumferential surface of the magnet retaining member, on the portion opposite to the protrusion (first structure).

[0032] In the first structure of the eddy current damper, a protrusion is provided on one or both of the inner circumferential surface of the conductive member and the outer circumferential surface of the opposing magnet holding member. When the eddy current damper is viewed in a cross-section (longitudinal section) along the central axis of the magnet holding member, the gap between the protrusion and its opposing portion is greater than the gap between the inner circumferential surface of the conductive member and the permanent magnet. Therefore, when the permanent magnet held on the magnet holding member moves close to the conductive member for some reason, the inner circumferential surface of the conductive member and the outer circumferential surface of the magnet holding member preferentially contact the protrusion. In this case, the permanent magnet does not contact the inner circumferential surface of the conductive member. Therefore, according to the first structure of the eddy current damper, contact between the permanent magnet and the conductive member can be prevented. In addition, by preventing contact between the permanent magnet and the conductive member, the gap between the permanent magnet and the conductive member can be reduced. As a result, the drag of the eddy current damper can be increased.

[0033] In the eddy current damper of the first structure, a sliding member is provided on the protrusion formed on the inner peripheral surface of the conductive member and / or the outer peripheral surface of the magnet holding member, or on the portion of the inner peripheral surface of the conductive member or the outer peripheral surface of the magnet holding member opposite to the protrusion. Therefore, the frictional resistance between the inner peripheral surface of the conductive member and the outer peripheral surface of the magnet holding member at the protrusion location can be reduced. Therefore, when the inner peripheral surface of the conductive member and the outer peripheral surface of the magnet holding member contact at the protrusion location, the resistance to rotation of the magnet holding member due to this contact can be suppressed. Furthermore, since wear on the inner peripheral surface of the conductive member and the outer peripheral surface of the magnet holding member can be reduced, the gap between the inner peripheral surface of the conductive member and the outer peripheral surface of the magnet holding member at the protrusion location can be maintained at a small level. Thus, contact between the permanent magnet and the conductive member can be prevented for a long period.

[0034] The gap between the protrusion and its opposite part is preferably less than 70% of the gap between the inner circumferential surface of the conductive component and the permanent magnet (second structure).

[0035] The aforementioned eddy current damper can also include a ball screw. The ball screw includes a nut and a screw shaft. The nut is fixed, for example, to one axial end of the magnet retaining member. The screw shaft passes through the nut. In this case, a protrusion (third structure) can also be configured axially closer to the end where the nut is fixed than the other end of the magnet retaining member.

[0036] As mentioned above, one of the main reasons for contact between the permanent magnet and the conductive component is the oscillation of the nut in a ball screw. In contrast, in the third structure, a protrusion is provided at both ends of the magnet retaining component along the axial direction, near the end of the fixed nut. Therefore, when using an eddy current damper, even if the rotating nut oscillates and the magnet retaining component moves towards the conductive component along with the nut, the protrusion will immediately contact the inner circumferential surface of the conductive component or the outer circumferential surface of the magnet retaining component, thereby limiting the movement of the magnet retaining component. Therefore, contact between the permanent magnet and the conductive component can be prevented more effectively.

[0037] The protrusions can also be disposed at both ends of the magnet holding member along the axial direction. Alternatively, the protrusions can be disposed at positions in the conductive member corresponding to the two ends of the magnet holding member (fourth structure).

[0038] In the fourth structure, protrusions are arranged at both ends of the magnet holding member along the axial direction or at positions corresponding to the ends of the magnet holding member in the conductive member. In this case, the inner circumferential surface of the conductive member contacts the outer circumferential surface of the magnet holding member through multiple protrusions. Therefore, the load between the inner circumferential surface of the conductive member and the outer circumferential surface of the magnet holding member can be distributed to multiple protrusions, thereby reducing the contact surface pressure between each protrusion and the inner circumferential surface of the conductive member or the outer circumferential surface of the magnet holding member.

[0039] The protrusion can also be provided on the outer peripheral surface of the magnet retaining component (fifth structure).

[0040] When viewing the eddy current damper in a cross-section along the central axis, the protrusion can also have an arc shape (sixth structure).

[0041] In the sixth structure, in the longitudinal section of the eddy current damper, the protrusion has an arc shape. In this case, since the protrusion can make linear contact with the opposing part, the contact area between the protrusion and the opposing part is reduced. As a result, the frictional resistance between the inner peripheral surface of the conductive component at the protrusion position and the outer peripheral surface of the magnet holding component can be reduced.

[0042] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same or equivalent structures are labeled with the same symbols, and the same descriptions are not repeated.

[0043] <First Implementation Method>

[0044] [Overall structure of eddy current damper]

[0045] Figure 1 This is a longitudinal cross-sectional view showing the schematic structure of the eddy current damper 10 according to the first embodiment. The eddy current damper 10 is mounted on a column or beam of a building, for example, by mounting components 20a and 20b, to suppress the vibration of the building.

[0046] Reference Figure 1 The eddy current damper 10 includes a conductive component 1, a magnet holding component 2, multiple permanent magnets 3, and a ball screw 4.

[0047] (Conductive components)

[0048] The conductive component 1 has the following characteristics: Figure 1 The dotted line X shown represents the cylindrical shape of the central axis. The conductive component 1, for example, has a substantially cylindrical shape. Hereinafter, with respect to the eddy current damper 10 and its constituent parts, the direction in which the central axis X of the conductive component 1 extends is referred to as the axial direction, and the radial direction of the circle or cylinder around the central axis X is simply referred to as the radial direction.

[0049] The conductive component 1 is supported at both axial ends by support components 51 and 52. Support components 51 and 52 are each cylindrical. In this embodiment, the portion of support components 51 and 52 on the conductive component 1 side is formed as a conical cylinder, while the other portions are cylindrical. Support components 51 and 52 are substantially coaxially arranged with the conductive component 1. One support component 51 is connected to one axial end of the conductive component 1. The other support component 52 is connected to the other axial end of the conductive component 1. The support components 52 are mounted on a column or beam of a building via mounting component 20b. Thus, the conductive component 1 is fixed to the building.

[0050] exist Figure 1 In the example, the support members 51 and 52 are integrally formed with the conductive member 1. However, the support members 51 and 52 may also be separate from the conductive member 1. When the support members 51 and 52 are separate from the conductive member 1, the support members 51 and 52 can be connected to the conductive member 1, for example, using bolts.

[0051] The conductive component 1 is made of a conductive material. The material of the conductive component 1 can be a strongly magnetic material such as carbon steel or cast iron. Alternatively, the material of the conductive component 1 can be a weakly magnetic material such as ferritic stainless steel, or a non-magnetic material such as aluminum alloy, austenitic stainless steel, or copper alloy.

[0052] (Magnet holding component)

[0053] The magnet holding member 2 is cylindrical. For example, it is substantially cylindrical. The magnet holding member 2 has a central axis X common to the conductive member 1 and is disposed inside the conductive member 1. That is, the magnet holding member 2 is substantially coaxial with the conductive member 1 in the radial direction inside the conductive member 1. The magnet holding member 2 is configured to be rotatable about the central axis X.

[0054] The two ends of the magnet holding component 2 are supported by support components 61 and 62 in the axial direction. The support components 61 and 62 are respectively arranged in the radial direction inside the support components 51 and 52 of the conductive component 1.

[0055] A support member 61 includes, for example, an annular flange portion 611 and a cylindrical portion 612. The flange portion 611 and the cylindrical portion 612 are substantially coaxially arranged with the magnet retaining member 2. The flange portion 611 is fixed to one axial end of the magnet retaining member 2 via a ball screw 4. The cylindrical portion 612 extends from the flange portion 611 toward the mounting member 20a. The cylindrical portion 612 is inserted into the cylindrical portion of the support member 51 of the conductive member 1.

[0056] Another support member 62 includes, for example, an annular flange portion 621 and a cylindrical portion 622. The flange portion 621 and the cylindrical portion 622 are substantially coaxially configured with the magnet retaining member 2. The flange portion 621 is connected to the other axial end of the magnet retaining member 2. The cylindrical portion 622 extends from the flange portion 621 toward the mounting member 20b. The cylindrical portion 622 is inserted into the cylindrical portion of the support member 52 of the conductive member 1.

[0057] exist Figure 1 In the example, the support member 62 is integrally formed with the magnet retaining member 2. However, the support member 62 may also be separate from the magnet retaining member 2. In the case where the support member 62 is separate from the magnet retaining member 2, the support member 62 can be connected to the magnet retaining member 2, for example, using bolts.

[0058] Bearings 71 and 72 for supporting axial loads are provided between the support members 51 and 52 of the conductive member 1 and the support members 61 and 62 of the magnet holding member 2. In this embodiment, the bearing 71 is axially disposed between the cylindrical portion of the support member 51 and the flange portion 611 of the support member 61. The bearing 72 is axially disposed between the cylindrical portion of the support member 52 and the flange portion 621 of the support member 62.

[0059] Bearings 81 and 82 for supporting radial loads are also provided between the support members 51 and 52 of the conductive member 1 and the support members 61 and 62 of the magnet retaining member 2. In this embodiment, the bearing 81 is radially disposed between the cylindrical portion of the support member 51 and the cylindrical portion 612 of the support member 61. The bearing 82 is radially disposed between the cylindrical portion of the support member 52 and the cylindrical portion 622 of the support member 62.

[0060] As bearings 71, 72, 81, and 82, known bearings can be appropriately selected and used. Bearings 71 and 72 used to support axial loads can be, for example, rolling bearings such as ball bearings or roller bearings, or sliding bearings. Similarly, bearings 81 and 82 used to support radial loads can be, for example, rolling bearings such as ball bearings or roller bearings, or sliding bearings.

[0061] In this embodiment, the magnet holding member 2 is made of a magnetic material. Preferably, the magnet holding member 2 is made of a material with high magnetic permeability. Materials with high magnetic permeability include, for example, strongly magnetic materials such as carbon steel or cast iron.

[0062] (Permanent magnet)

[0063] Multiple permanent magnets 3 are held by the outer peripheral surface of the magnet holding member 2. Each of the permanent magnets 3 is fixed to the outer peripheral surface of the magnet holding member 2, for example, by an adhesive. Each of the permanent magnets 3 can also be fixed to the outer peripheral surface of the magnet holding member 2 by bolts or the like. The permanent magnets 3 are spaced apart from the inner peripheral surface of the conductive member 1 and face each other.

[0064] Figure 2 This is a cross-sectional view (transverse section) of the eddy current damper 10 cut by a plane perpendicular to the central axis X. Figure 2 In the text, only a portion of the conductive component 1, the magnet holding component 2, and the multiple permanent magnets 3 are represented.

[0065] Reference Figure 2The permanent magnets 3 are arranged circumferentially on the outer peripheral surface of the magnet holding member 2. These permanent magnets 3 are arranged substantially at equal intervals along the entire circumference of the magnet holding member 2. In this embodiment, the individual magnetic poles (N pole and S pole) of the permanent magnets 3 are arranged radially. The permanent magnets 3 are arranged on the magnet holding member 2 such that adjacent permanent magnets 3 in the circumferential direction of the magnet holding member 2 have opposite magnetic poles. That is, in a certain permanent magnet 3, the N pole is arranged radially outward and the S pole is arranged radially inward; in the permanent magnets 3 located on both sides of this permanent magnet 3, the S pole is arranged radially outward and the N pole is arranged radially inward.

[0066] (Ball screw)

[0067] return Figure 1 The ball screw 4 includes a nut 41 and a screw shaft 42.

[0068] The nut 41 includes an annular flange portion 411 and a cylindrical portion 412. The flange portion 411 and the cylindrical portion 412 are substantially coaxially arranged with the magnet retaining member 2. The flange portion 411 is disposed between the magnet retaining member 2 and the support member 61. More specifically, the flange portion 411 is disposed between one axial end of the magnet retaining member 2 and the flange portion 611 of the support member 61. The cylindrical portion 412 extends from the flange portion 411 into the magnet retaining member 2.

[0069] Nut 41 is fixed to magnet holding member 2. More specifically, nut 41 is fixed to one axial end of magnet holding member 2 via flange 411. Nut 41 is also fixed to support member 61 of magnet holding member 2. More specifically, nut 41 is fixed to flange 611 of support member 61 via flange 411. Nut 41 is fixed to magnet holding member 2 and support member 61, for example, by bolts.

[0070] The screw shaft 42 passes through the nut 41. The screw shaft 42 is configured to move axially relative to the nut 41, and with axial movement, the nut 41 rotates about the screw shaft 42 (central axis X). As the nut 41 rotates, the magnet retaining member 2 rotates about the central axis X.

[0071] The ball bearing is located between the outer circumferential surface of the screw shaft 42 and the inner circumferential surface of the nut 41. As the screw shaft 42 moves axially, the ball bearing rolls along the screw grooves located on the outer circumferential surface of the screw shaft 42 and the inner circumferential surface of the nut 41. One axial end of the screw shaft 42 is mounted on a column or beam of the building via a mounting component 20a. That is, the screw shaft 42 is fixed to the building.

[0072] [Detailed Structure of Eddy Current Dampers]

[0073] Figure 3This is a longitudinal section of the eddy current damper 10. Figure 1 A magnified view of a portion of the image. Below, refer to... Figure 3 A more detailed description of the structure of the eddy current damper 10 is provided below.

[0074] like Figure 3 As shown, in this embodiment, radially protruding protrusions 21 and 22 are provided on the outer peripheral surface of the magnet holding member 2. The protrusions 21 and 22 are portions of the outer peripheral surface of the magnet holding member 2 that protrude towards the conductive member 1 compared to other portions. The protrusions 21 and 22 protrude towards the conductive member 1 relative to the permanent magnet 3. That is, a portion of the surface of the protrusions 21 and 22 is located radially outside the permanent magnet 3.

[0075] The protrusions 21 and 22 extend circumferentially along the magnet holding member 2. Preferably, the protrusions 21 and 22 are respectively provided on the entire circumference of the magnet holding member 2. For example, the protrusions 21 and 22 are provided continuously on the entire circumference of the magnet holding member 2. That is, the protrusions 21 and 22 are respectively, for example, annular. Alternatively, the protrusions 21 and 22 may also be divided into multiple portions in the circumferential direction of the magnet holding member 2.

[0076] Protrusions 21 and 22 are axially disposed on both sides of the permanent magnet 3. Protrusions 21 and 22 are respectively disposed at both axial ends of the magnet holding member 2. One protrusion 21 is disposed on the outer peripheral surface of the magnet holding member 2 at one axial end, in other words, at the end adjacent to the nut 41. The other protrusion 22 is disposed on the outer peripheral surface of the magnet holding member 2 at the other axial end, in other words, at the end away from the nut 41.

[0077] In this embodiment, the eddy current damper 10 further includes sliding members 91 and 92. Sliding member 91 is disposed on the inner circumferential surface of the conductive member 1, opposite to the protrusion 21 disposed on the outer circumferential surface of the magnet holding member 2. Sliding member 92 is disposed on the inner circumferential surface of the conductive member 1, opposite to the protrusion 22 disposed on the outer circumferential surface of the magnet holding member 2. Sliding members 91 and 92 are continuously disposed along the entire circumference of the conductive member 1.

[0078] Slider members 91 and 92 have a coefficient of friction smaller than that of the inner circumferential surface of the conductive member 1 and the outer circumferential surface of the magnet retaining member 2. Slider members 91 and 92 can be made of a low-friction material, such as fluororesin. Alternatively, a groove can be provided on the inner circumferential surface of the conductive member 1, and a low-friction material can be embedded in this groove to serve as slider members 91 and 92. Or, slider members 91 and 92 can also be a coating made of a low-friction material.

[0079] From along the central axis X ( Figure 1When observing the eddy current damper 10 in a longitudinal section, a gap g1 is formed between the protrusion 21 on the outer peripheral surface of the magnet holding member 2 and the portion of the eddy current damper 10 that is radially opposite to the protrusion 21 (opposing portion). The gap g1 is smaller than the gap G between the inner peripheral surface of the conductive member 1 and the permanent magnet 3. Similarly, when observing the eddy current damper 10 in a longitudinal section, a gap g2 is formed between the protrusion 22 on the outer peripheral surface of the magnet holding member 2 and the portion of the eddy current damper 10 that is radially opposite to the protrusion 22 (opposing portion). The gap g2 is smaller than the gap G between the inner peripheral surface of the conductive member 1 and the permanent magnet 3. Gap g1 and g2 are spaces between the inner peripheral surface of the conductive member 1 and the outer peripheral surface of the magnet holding member 2, located at the positions of the protrusions 21 and 22. When the eddy current damper 10 is viewed in longitudinal section, the gaps g1 and g2 are defined by the shortest distance from the protrusions 21 and 22 to their opposite portions. As in this embodiment, when the sliding members 91 and 92 are provided on the inner circumferential surface of the conductive member 1, the gaps g1 and g2 are respectively the radial distances from the top surfaces of the protrusions 21 and 22 to the surfaces of the sliding members 91 and 92. On the other hand, when the eddy current damper 10 is viewed in longitudinal section, the gap G is defined by the shortest distance between the conductive member 1 and the permanent magnet 3. In other words, the gap G is the radial distance from the surface of the permanent magnet 3 to the inner circumferential surface of the conductive member 1.

[0080] The gaps g1 and g2 formed between the protrusions 21 and 22 and the sliding members 91 and 92 can be, for example, less than 70% of the gap G between the conductive member 1 and the permanent magnet 3. Although not particularly limited, the gap G between the conductive member 1 and the permanent magnet 3 can be, for example, more than 0.5 mm and less than 2.0 mm. The axial distance between each of the protrusions 21 and 22 and the permanent magnet 3 can be, for example, about 5 times the gap G.

[0081] [Operation of the eddy current damper]

[0082] Refer again Figure 1 When a building vibrates due to earthquakes or other events, and vibration is input to the eddy current damper 10, the screw shaft 42 of the ball screw 4 moves axially. Simultaneously, the nut 41 of the ball screw 4 rotates about the central axis X. The magnet retaining member 2 and the permanent magnet 3 rotate together with the nut 41 about the central axis X. As a result, the permanent magnet 3 rotates relative to the conductive member 1 fixed to the building, thus generating eddy currents in the conductive member 1. Through the interaction between these eddy currents and the magnetic field formed by the permanent magnet 3, a resistance (Lorentz force) is generated in the opposite direction to the rotation of the nut 41 and the magnet retaining member 2, hindering their rotation. Consequently, the axial movement of the screw shaft 42 is also hindered, and the vibration of the building is attenuated.

[0083] [Effect]

[0084] In the eddy current damper 10 of this embodiment, protrusions 21 and 22 are provided on the outer peripheral surface of the magnet holding member 2. Furthermore, the gaps g1 and g2 between the protrusions 21 and 22 and their opposite portions, i.e., the sliding members 91 and 92, are smaller than the gap G between the inner peripheral surface of the conductive member 1 and the permanent magnet 3. Therefore, during the operation of the eddy current damper 10, when the magnet holding member 2 and the permanent magnet 3 move close to the conductive member 1 for some reason, the protrusions 21 and 22 of the magnet holding member 2 contact the opposite portion on the conductive member 1 side preferentially before the permanent magnet 3. Thus, contact between the permanent magnet 3 and the conductive member 1 can be prevented. Furthermore, since contact between the permanent magnet 3 and the conductive member 1 is not generated, the gap G between the permanent magnet 3 and the conductive member 1 can be reduced. As a result, the resistance of the eddy current damper 10 can be increased.

[0085] In this embodiment, sliding members 91 and 92 are provided on the inner circumferential surface of the conductive member 1 at the portion opposite to the protrusions 21 and 22. This reduces the frictional resistance between the protrusions 21 and 22 and the conductive member 1. Therefore, during the operation of the eddy current damper 10, when the protrusions 21 and 22 contact the conductive member 1, the situation where this contact hinders the rotation of the magnet holding member 2 can be suppressed. Furthermore, wear on the protrusions 21 and 22, as well as wear on the portion of the inner circumferential surface of the conductive member 1 opposite to the protrusions 21 and 22, can be reduced. Therefore, the widening of gaps g1 and g2 at the positions of the protrusions 21 and 22 with the use of the eddy current damper 10 can be suppressed. That is, since gaps g1 and g2 can be kept small, contact between the permanent magnet 3 and the conductive member 1 can be prevented for a long period.

[0086] In this embodiment, protrusions 21 and 22 are respectively provided at both ends of the magnet holding member 2 along the axial direction. Therefore, during the operation of the eddy current damper 10, when the magnet holding member 2 holding the permanent magnet 3 moves close to the conductive member 1, the outer peripheral surface of the magnet holding member 2 contacts the opposite portion on the conductive member 1 side through the multiple protrusions 21 and 22. Therefore, the load between the inner peripheral surface of the conductive member 1 and the outer peripheral surface of the magnet holding member 2 can be distributed to the multiple protrusions 21 and 22, and the contact surface pressure between each of the protrusions 21 and 22 and the conductive member 1 can be reduced.

[0087] In this embodiment, the protrusion 21 is positioned closer to the end adjacent to the nut 41 than the end furthest from the nut 41 at either end of the magnet holding member 2 along its axial direction. That is, the protrusion 21 is positioned near the nut 41. Therefore, when using the eddy current damper 10, even if the rotating nut 41 swings and the magnet holding member 2 moves towards the conductive member 1 along with the nut 41, the protrusion 21 will immediately contact the opposite portion on the conductive member 1 side, thereby limiting the movement of the magnet holding member 2. Therefore, contact between the permanent magnet 3 and the conductive member 1 can be prevented more effectively.

[0088] In this embodiment, protrusions 21 and 22 are provided on the outer peripheral surface of the magnet holding member 2. On the other hand, no portion protruding toward the magnet holding member 2 is provided on the inner peripheral surface of the conductive member 1 beyond the radially outer surface of the permanent magnet 3. In this case, the eddy current damper 10 can be easily disassembled.

[0089] <Second Implementation Method>

[0090] Figure 4 This is a longitudinal sectional view of the eddy current damper 10A according to the second embodiment, and is an enlarged view showing a portion of the eddy current damper 10A. (See attached image.) Figure 4 As shown, the difference between the eddy current damper 10A of this embodiment and the eddy current damper 10 of the first embodiment is that the protrusion 21 is provided only near the nut 41 on the outer peripheral surface of the magnet holding member 2.

[0091] The eddy current damper 10A of this embodiment also achieves the same effect as the eddy current damper 10 of the first embodiment. That is, during the operation of the eddy current damper 10A, even when the magnet holding member 2 and the permanent magnet 3 move close to the conductive member 1, the protrusion 21 of the magnet holding member 2 can contact the opposite portion on the conductive member 1 side preferentially before the permanent magnet 3. Therefore, contact between the permanent magnet 3 and the conductive member 1 can be prevented, and the gap G between the permanent magnet 3 and the conductive member 1 can be reduced. In addition, since the protrusion 21 is provided near the nut 41, contact between the permanent magnet 3 and the conductive member 1 can be effectively prevented, especially due to the swing of the nut 41, when the magnet holding member 2 and the permanent magnet 3 approach the conductive member 1.

[0092] <Third Implementation Method>

[0093] Figure 5 This is a longitudinal sectional view of the eddy current damper 10B according to the third embodiment, and is an enlarged view showing a portion of the eddy current damper 10B. Figure 5As shown, the difference between the eddy current damper 10B of this embodiment and the eddy current damper 10 of the first embodiment is that the sliding members 91 and 92 are not provided on the conductive member 1, but on the protrusions 21 and 22 of the magnet holding member 2.

[0094] Even when the sliders 91 and 92 are configured as in this embodiment, the frictional resistance between the protrusions 21 and 22 and the conductive member 1 can be reduced, just as in the first embodiment. Therefore, it is possible to suppress the resistance to rotation of the magnet holding member 2 due to contact between the protrusions 21 and 22 and the conductive member 1. Furthermore, wear on the inner circumferential surfaces of the protrusions 21 and 22 and the conductive member 1 can be reduced.

[0095] <Fourth Implementation Method>

[0096] Figure 6 This is a longitudinal sectional view of the eddy current damper 10C according to the fourth embodiment, and is an enlarged view showing a portion of the eddy current damper 10C. Figure 6 As shown, the difference between the eddy current damper 10C of this embodiment and the eddy current damper 10 of the first embodiment is that the protrusions 11 and 12 are provided on the inner peripheral surface of the conductive member 1 instead of the outer peripheral surface of the magnet holding member 2.

[0097] In this embodiment, radially protruding protrusions 11 and 12 are provided on the inner peripheral surface of the conductive member 1. The protrusions 11 and 12 are portions of the inner peripheral surface of the conductive member 1 that protrude towards the magnet holding member 2 compared to other portions. Sliding members 91 and 92 are provided on the protrusions 11 and 12. However, the sliding members 91 and 92 may also be provided on the outer peripheral surface of the magnet holding member 2, at the portion opposite to the protrusions 11 and 12.

[0098] The protrusions 11 and 12 extend circumferentially along the conductive member 1 and the magnet holding member 2, respectively. Preferably, the protrusions 11 and 12 are respectively provided on the entire circumference of the conductive member 1. For example, the protrusions 11 and 12 are provided continuously on the entire circumference of the conductive member 1. That is, the protrusions 11 and 12 are respectively, for example, annular. Alternatively, the protrusions 11 and 12 may be divided into multiple portions in the circumferential direction of the conductive member 1.

[0099] Protrusions 11 and 12 and protrusions 21 and 22 in the first embodiment ( Figure 3 Similarly, protrusions 11 and 12 are axially disposed on both sides of the permanent magnet 3. Protrusions 11 and 12 are respectively disposed in the conductive member 1 at positions corresponding to the two axial ends of the magnet holding member 2. One protrusion 11 is disposed on one axial end side of the inner circumferential surface of the conductive member 1. Protrusion 11 is disposed at one of the two axial ends of the magnet holding member 2 near the end of the fixing nut 41. The other protrusion 12 is disposed on the other axial end side of the inner circumferential surface of the conductive member 1.

[0100] Similar to the first embodiment, a gap g1 is formed between the protrusion 11 on the inner peripheral surface of the conductive member 1 and the portion (opposing portion) of the eddy current damper 10C that is radially opposite to the protrusion 11. The gap g1 is smaller than the gap G between the inner peripheral surface of the conductive member 1 and the permanent magnet 3. Furthermore, a gap g2 is formed between the protrusion 12 on the inner peripheral surface of the conductive member 1 and the portion (opposing portion) of the eddy current damper 10C that is radially opposite to the protrusion 12. The gap g2 is smaller than the gap G between the inner peripheral surface of the conductive member 1 and the permanent magnet 3. When the eddy current damper 10C is viewed in longitudinal section, the gaps g1 and g2 are defined by the shortest distance from the sliding members 91 and 92 on the protrusions 11 and 12 to the opposing portions of the protrusions 11 and 12. Figure 6 In the example, gaps g1 and g2 are the radial distances from the surfaces of sliders 91 and 92 to the outer peripheral surface of magnet retaining component 2, respectively.

[0101] In this embodiment, the eddy current damper 10C achieves the same effect as the eddy current damper 10 of the first embodiment because the gaps g1 and g2 between the protrusions 11 and 12 and their opposite portions are smaller than the gap G between the inner circumferential surface of the conductive member 1 and the permanent magnet 3. That is, during the operation of the eddy current damper 10C, when the magnet holding member 2 and the permanent magnet 3 move close to the conductive member 1 for some reason, the magnet holding member 2 contacts the protrusions 11 and 12 of the conductive member 1 preferentially before the permanent magnet 3. Therefore, contact between the permanent magnet 3 and the conductive member 1 can be prevented.

[0102] In this embodiment, a plurality of protrusions 11 and 12 are provided on the inner peripheral surface of the conductive component 1. However, as in the second embodiment, for example, only one protrusion 11 may be provided on the inner peripheral surface of the conductive component 1.

[0103] <Fifth Implementation Method>

[0104] Figure 7 This is a longitudinal sectional view of the eddy current damper 10D according to the fifth embodiment, and is an enlarged view showing a portion of the eddy current damper 10D. The difference between the eddy current damper 10D of this embodiment and the eddy current dampers of the above embodiments is that protrusions are provided on both the inner peripheral surface of the conductive member 1 and the outer peripheral surface of the magnet holding member 2.

[0105] like Figure 7As shown, protrusions 11 and 12 are provided on the inner peripheral surface of the conductive component 1. Protrusions 21 and 22 are provided on the outer peripheral surface of the magnet holding component 2. The protrusions 11 and 12 of the conductive component 1 are radially opposite to the protrusions 21 and 22 of the magnet holding component 2. Sliding members 91 and 92 are provided on the protrusions 21 and 22 of the magnet holding component 2. However, sliding members 91 or 92 may also be provided on the protrusions 11 or 12 of the conductive component 1.

[0106] The gap g1 formed between the protrusion 11 on the inner peripheral surface of the conductive component 1 and the protrusion 21 on the outer peripheral surface of the magnet holding component 2 is smaller than the gap G between the inner peripheral surface of the conductive component 1 and the permanent magnet 3. Similarly, the gap g2 formed between the protrusion 12 on the inner peripheral surface of the conductive component 1 and the protrusion 22 on the outer peripheral surface of the magnet holding component 2 is smaller than the gap G between the inner peripheral surface of the conductive component 1 and the permanent magnet 3. Gap g1 and g2 are the radial distances from the surfaces of the sliding members 91 and 92 on the protrusions 21 and 22 to the top surfaces of the protrusions 11 and 12, respectively.

[0107] The eddy current damper 10D of this embodiment also achieves the same effect as the eddy current damper 10 of the first embodiment because the gaps g1 and g2 between the protrusions 11 and 12 of the conductive member 1 and the protrusions 21 and 22 of the magnet holding member 2 opposite to them are smaller than the gap G between the inner peripheral surface of the conductive member 1 and the permanent magnet 3. That is, during the operation of the eddy current damper 10D, when the magnet holding member 2 and the permanent magnet 3 move close to the conductive member 1 for some reason, the protrusions 21 and 22 of the magnet holding member 2 contact the protrusions 11 and 12 of the conductive member 1 preferentially before the permanent magnet 3. Therefore, contact between the permanent magnet 3 and the conductive member 1 can be prevented.

[0108] In this embodiment, a plurality of protrusions 11 and 12 are provided on the inner peripheral surface of the conductive member 1, and a plurality of protrusions 21 and 22 are provided on the outer peripheral surface of the magnet holding member 2. However, for example, only one protrusion 11 may be provided on the inner peripheral surface of the conductive member 1. Similarly, for example, only one protrusion 21 may be provided on the outer peripheral surface of the magnet holding member 2.

[0109] The structures of the eddy current dampers in the above embodiments, especially the structures of the protrusions 11, 12, 21, 22 and the sliding members 91, 92, can be appropriately combined.

[0110] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. Various modifications can be made as long as they do not depart from the spirit of the invention.

[0111] In the above embodiments, in the longitudinal cross-sectional view of the eddy current damper, the protrusions 11 and 12 on the inner peripheral surface of the conductive component 1 and the protrusions 21 and 22 on the outer peripheral surface of the magnet holding component 2 are rectangular. However, the shapes of the protrusions 11, 12, 21, and 22 are not limited to this.

[0112] For example, such as Figure 8 As shown, the protrusions 21 and 22 on the outer peripheral surface of the magnet retaining member 2 can also have a convex arc shape on the conductive member 1 side in the longitudinal sectional view of the eddy current damper. In this case, even if the protrusions 21 and 22 of the magnet retaining member come into contact with the conductive member 1 during the use of the eddy current damper, the protrusions 21 and 22 can make linear contact with the conductive member 1, thus reducing the contact area. Therefore, the frictional resistance between the inner peripheral surface of the conductive member 1 and the outer peripheral surface of the magnet retaining member 2 at the location of the protrusions 21 and 22 can be reduced. Although the figure is omitted, the protrusions 11 and 12 on the inner peripheral surface of the conductive member 1 ( Figure 6 and Figure 7 It is also possible for the eddy current damper to have a convex arc shape on the magnet holding member 2 side in the longitudinal sectional view. In the longitudinal sectional view of the eddy current damper, when the protrusions 11, 12 of the conductive member 1 or the protrusions 21, 22 of the magnet holding member 2 have an arc shape, the gaps g1, g2 become the radial distance between the apex of the protrusions 11, 12 or the protrusions 21, 22 and their opposite portions. In this case, as Figure 8 As shown, sliders 91 and 92 can also be provided on the portion of the inner circumferential surface of the conductive member 1 opposite to the protrusions 21 and 22, or on the portion of the outer circumferential surface of the magnet holding member 2 opposite to the protrusions 11 and 12. Alternatively, sliders 91 and 92 can be provided on the protrusions 11 and 12 or the protrusions 21 and 22.

[0113] The eddy current dampers of the above embodiments have bearings 81 and 82 for supporting radial loads. However, as Figure 9 As shown, the gap between the inner circumferential surface of the conductive member 1 at the protrusions 21 and 22 and the outer circumferential surface of the magnet retaining member 2 is very small. When the magnet retaining member 2 rotates, the conductive member 1 and the magnet retaining member 2 are almost always in contact at the protrusions 21 and 22. Therefore, when the sliding members 91 and 92 function as sliding bearings for supporting radial loads, bearings 81 and 82 can be omitted. Figure 1 Similarly, when protrusions 11 and 12 are provided on the inner peripheral surface of the conductive component 1 ( Figure 6 and Figure 7 The gap between the inner circumferential surface of the conductive component 1 at the positions of the protrusions 11 and 12 and the outer circumferential surface of the magnet retaining component 2 is very small, and when the sliding components 91 and 92 function as sliding bearings for supporting radial loads, bearings 81 and 82 can be omitted. Figure 1 This enables the axial miniaturization of eddy current dampers.

[0114] In the eddy current dampers of the above embodiments, a row of permanent magnets 3 arranged circumferentially is provided on the outer peripheral surface of the magnet holding member 2. However, multiple rows of permanent magnets 3 may also be provided on the outer peripheral surface of the magnet holding member 2. In this case, the protrusions provided on the inner peripheral surface of the conductive member 1 and / or the outer peripheral surface of the magnet holding member 2 may be arranged between the rows of permanent magnets 3.

[0115] In the first to third embodiments and the fifth embodiment described above, one protrusion 21 or two protrusions 21, 22 are provided on the outer peripheral surface of the magnet holding member 2. In the fourth and fifth embodiments described above, one protrusion 11 or two protrusions 11, 22 are provided on the inner peripheral surface of the conductive member 1. However, the number of protrusions provided on one or both of the inner peripheral surface of the conductive member 1 and the outer peripheral surface of the magnet holding member 2 is not particularly limited. For example, three or more protrusions may be provided on the outer peripheral surface of the magnet holding member 2. Similarly, three or more protrusions may be provided on the inner peripheral surface of the conductive member 1.

[0116] In the above embodiments and their variations, the eddy current damper ( Figure 1 and Figures 3-9 The diagram shows examples of protrusions 11, 12, or 21, 22 integrally formed with the conductive member 1 or the magnet retaining member 2, but is not limited to this. The protrusions may also be components different from the conductive member 1 or the magnet retaining member 2. When the protrusions are different from the conductive member 1 or the magnet retaining member 2, they can be mounted on the conductive member 1 or the magnet retaining member 2, for example, by bolts. Alternatively, the protrusions may be made of a material having a coefficient of friction smaller than that of the conductive member 1 and the magnet retaining member 2, allowing the protrusions themselves to function as sliding elements.

[0117] In the embodiments described above, the magnetic poles (N pole and S pole) of the permanent magnet 3 are arranged radially along the magnet holding member 2. However, the magnetic poles (N pole and S pole) of the permanent magnet 3 may also be arranged circumferentially along the magnet holding member 2. In this case, it is preferable to arrange pole pieces between adjacent permanent magnets 3 in the circumferential direction, and the magnet holding member 2 is preferably made of a non-magnetic material.

[0118] Symbol Explanation

[0119] 10, 10A, 10B, 10C, 10D: Eddy current dampers

[0120] 1: Conductive components

[0121] 11, 12: convex part

[0122] 2: Magnet retaining components

[0123] 21, 22: convex part

[0124] 3: Permanent magnets

[0125] 4: Ball screw

[0126] 41: Nut

[0127] 42: Screw shaft

[0128] 91, 92: Sliding parts

Claims

1. An eddy current damper, comprising: A conductive component, which is cylindrical; A magnet holding component, disposed inside the conductive component, has a cylindrical shape and is configured to rotate about a central axis; Multiple permanent magnets are arranged circumferentially along the magnet holding member and held by the outer peripheral surface of the magnet holding member, and are opposed to the inner peripheral surface of the conductive member by a gap; A sliding member having a coefficient of friction smaller than that of the inner peripheral surface of the conductive member and the outer peripheral surface of the magnet retaining member. One or both of the inner circumferential surface of the conductive component and the outer circumferential surface of the magnet retaining component are provided with a protrusion that protrudes radially toward the conductive component or the magnet retaining component and extends circumferentially. When the eddy current damper is viewed in cross-section along the central axis, a gap is formed between the protrusion and its radially opposite portion. This gap is smaller than the gap between the inner circumferential surface of the conductive member and the permanent magnet. The slider is disposed in the portion of the protrusion, or the inner peripheral surface of the conductive component, or the outer peripheral surface of the magnet retaining component, opposite to the protrusion.

2. The eddy current damper as described in claim 1, wherein, The gap between the protrusion and the opposing portion is less than 70% of the gap between the inner circumferential surface of the conductive component and the permanent magnet.

3. The eddy current damper as described in claim 1 or 2, wherein, It also includes a ball screw, which comprises: a nut fixed to one end of the magnet retaining member along its axial direction; and a screw shaft passing through the nut. The protrusion is positioned axially closer to one end than the other end of the magnet retaining member.

4. The eddy current damper as described in claim 1 or 2, wherein, The protrusions are respectively arranged at the two ends of the magnet holding member along the axial direction or at the positions corresponding to the two ends in the conductive member.

5. The eddy current damper as described in claim 1 or 2, wherein, The protrusion is disposed on the outer peripheral surface of the magnet retaining member.

6. The eddy current damper as described in claim 1 or 2, wherein, The protrusion has an arc shape when the eddy current damper is viewed in cross-section along the central axis.

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