Static electricity removal device, motor

Abstract

To provide a technology capable of efficiently assembling a device that eliminates a problem caused by potential fluctuation in a shaft.SOLUTION: A static eliminator electrically connected to a shaft includes a frame, a conductor extending in a linear shape or in a strip shape, and a conductor holding portion that holds the conductor. The frame extends in the circumferential direction and is arranged radially outside of the shaft. The radially inner end portion of the frame radially faces at least a partial circumferential region of the radially outer surface of the shaft. The conductor holding portion has a plurality of first columns. The first columns extend axially from the frame and are arranged in the circumferential direction. Each of the frame and the first column has electrical conductivity. The same conductor is wound over at least two first columns. Between the first columns adjacent along the same conductor, the conductor is in contact with the shaft.SELECTED DRAWING: Figure 2A

Description

[Technical field]

[0001] The present invention relates to a static eliminator and a motor. [Background technology]

[0002] Conventionally, devices for grounding a shaft to prevent electrolytic corrosion of a motor are known. For example, in a charge discharge assembly for dissipating electrostatic charges accumulated on a shaft, a number of filaments arranged on the outer periphery of the shaft are formed in a U-shape around an annular molding plate to which the filaments are fixed. The assembly of the filaments and the annular molding plate is held in an annular channel formed in an annular frame. Distal end portions of the filaments extend past the inner diameter of the annular molding plate. The filaments contact the shaft when the motor is at rest or at a low speed. (See JP 2005-124391 A) [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-124391 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned electric charge discharge assembly, since the filaments are formed in a U-shape and arranged on the outer circumference of the shaft, the assembly is complicated and requires many steps, which may increase the manufacturing cost and reduce the productivity.

[0005] The present invention aims to provide a technique for efficiently assembling a device that eliminates problems caused by potential fluctuations within a shaft. [Means for solving the problem]

[0006] An exemplary static eliminator of the present invention is electrically connected to a shaft extending in the axial direction along a central axis. The static eliminator includes a frame extending in a circumferential direction centered on the central axis, a conductor extending in a linear or band shape, and a conductor holding part that holds the conductor. The frame is disposed radially outward from the shaft. A radially inner end of the frame faces radially at least a partial region in the circumferential direction of the radially outer surface of the shaft. The conductor holding part has a plurality of first column parts extending in the axial direction from the frame. Each of the first column parts is aligned in the circumferential direction. The frame and the first column parts are each electrically conductive. The same conductor is wound around at least two of the first column parts. Between the first column parts adjacent to each other along the same conductor, the conductor contacts the shaft.

[0007] An exemplary motor of the present invention includes the static eliminator, the shaft, and a rolling bearing. The shaft extends in an axial direction along the central axis. The rolling bearing supports the shaft so as to be rotatable about the central axis. Effect of the Invention

[0008] According to the exemplary static eliminator and motor of the present invention, a technique can be provided that enables efficient assembly of a device that eliminates problems caused by potential fluctuations in the shaft. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the configuration of a motor. [Figure 2A] FIG. 2A is a top view showing an example of the configuration of the static eliminator according to the embodiment. [Figure 2B] FIG. 2B is a side view of the static eliminator according to the embodiment. [Figure 3A] FIG. 3A is a top view showing a first modified example of the frame. [Figure 3B] FIG. 3B is a top view showing a second modified example of the frame. [Figure 3C]FIG. 3C is a top view showing a third modified example of the frame. [Figure 4] FIG. 4 is a side view showing another embodiment of the conductor. [Figure 5A] FIG. 5A is a top view showing a first modified example of the arrangement of the electric conductor holder. [Figure 5B] FIG. 5B is a top view showing a second modified example of the arrangement of the electric conductor holding portion. [Figure 6] FIG. 6 shows an example of a configuration in which different conductors are wound around different first pillar portions. [Figure 7] FIG. 7 is a side view showing a modified example of the arrangement of the first pillar portion. [Figure 8A] FIG. 8A is a side view showing a modified example of winding of the conductor. [Figure 8B] FIG. 8B is a side view showing another modified example of winding of the conductor. [Figure 9] FIG. 9 is a side view showing a configuration example of a static eliminator according to a first modified example. [Figure 10A] FIG. 10A is a top view showing a configuration example of a static eliminator according to a second modified example. [Figure 10B] FIG. 10B is a side view of the static eliminator according to the second modified example. [Figure 10C] FIG. 10C is a top view showing an example of a case where a conductor is broken in the second modified example. [Figure 11] FIG. 11 is a side view showing a configuration example of a static eliminator according to a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Exemplary embodiments are described below with reference to the drawings.

[0011] In this specification, in motor 1, the direction parallel to central axis CA is referred to as the "axial direction." Within the axial direction, the direction from bearing 131 to bearing 132, which will be described later, is referred to as the "one axial direction," and the direction from bearing 132 to bearing 131 is referred to as the "other axial direction." For each component, the end in one axial direction is referred to as the "one axial end," and the end in the other axial direction is referred to as the "other axial end." Additionally, for the surface of each component, the surface facing one axial direction is referred to as the "one axial end face," and the surface facing the other axial direction is referred to as the "other axial end face."

[0012] Additionally, the direction perpendicular to the central axis CA is referred to as the "radial direction." Within the radial direction, the direction approaching the central axis CA is referred to as the "radial inner direction," and the direction away from the central axis CA is referred to as the "radial outer direction." For each component, the end portion on the radial inner side is referred to as the "radial inner end portion," and the end portion on the radial outer side is referred to as the "radial outer end portion." Additionally, for the side surfaces of each component, the side surface facing radially inward is referred to as the "radial inner side surface," and the side surface facing radially outward is referred to as the "radial outer side surface."

[0013] Additionally, the direction of rotation about the central axis CA is referred to as the "circumferential direction." For each component, the end portion on one side of the circumferential direction is referred to as the "one circumferential end portion," and the end portion on the other side of the circumferential direction is referred to as the "other circumferential end portion." Additionally, for the side surfaces of each component, the side surface facing the circumferential direction is referred to as the "circumferential side surface." Furthermore, the side surface facing one side of the circumferential direction is referred to as the "one circumferential side surface," and the side surface facing the other side of the circumferential direction is referred to as the "other circumferential side surface."

[0014] In this specification, "annular" refers not only to a shape that is continuous and uninterrupted throughout the entire circumferential area centered on the central axis CA, but also to a shape that has one or more interruptions in a portion of the entire area centered on the central axis CA. It also refers to a shape that describes a closed curve on a curved surface that intersects with the central axis CA.

[0015] In addition, in the positional relationship between any one of a direction, a line, and a plane and any other, "parallel" includes not only a state in which the two do not intersect at all no matter how far they are extended, but also a state in which they are substantially parallel. Furthermore, "perpendicular" and "orthogonal" each include not only a state in which the two intersect at 90 degrees, but also a state in which they are substantially perpendicular and a state in which they are substantially orthogonal, respectively. In other words, "parallel," "perpendicular," and "orthogonal" each include a state in which there is an angle deviation in the positional relationship between the two to an extent that does not deviate from the gist of the present invention.

[0016] Note that these are names used merely for the purpose of explanation, and are not intended to limit the actual positional relationships, directions, names, and the like.

[0017] <1. Embodiment> Fig. 1 is a cross-sectional view showing an example of the configuration of a motor 1. Fig. 1 shows the cross-sectional structure of the motor 1 taken along an imaginary cutting plane including a central axis CA.

[0018] <1-1.Motor> The motor 1 includes a shaft 10, a rotor 11, a stator 12, bearings 131 and 132, a housing 14, a bearing holder 15, a substrate 16, and a static eliminator 2. As shown in Fig. 1, the motor 1 is an inner rotor type motor in which the rotor 11 is disposed radially inward from the stator 12. However, the present invention is not limited to this example, and the motor 1 may be an outer rotor type motor in which the rotor 11 is disposed radially outward from the stator 12.

[0019] The shaft 10 extends in the axial direction along the central axis. The shaft 10 supports the rotor 11 and is rotatable together with the rotor 11 about the central axis CA. The rotor 11 is fixed to the radially outer surface of the shaft 10. The stator 12 is annular and surrounds the central axis CA, and is held in a housing 14. The stator 12 drives and rotates the rotor 11 in response to the supply of a drive current. Note that this is not limited to the example, and the shaft 10 may be a fixed shaft attached to the stator 12. Note that when the shaft 10 is a fixed shaft, a rolling bearing is disposed between the rotor 11 and the shaft 10 instead of the bearings 131 and 132.

[0020] Each of the bearings 131, 132 is a rolling bearing such as a ball bearing or a roller bearing, and supports the shaft 10 rotatably about the central axis CA. The inner rings of the bearings 131, 132 are fixed to the radially outer surface of the shaft 10. The outer ring of the bearing 131 is fixed to an inner cylinder portion 143 (described later) of the housing 14. The outer ring of the bearing 132 is fixed to the bearing holder 15. Note that this is not limiting, and one of the bearings 131, 132 does not have to be a rolling bearing, and may be, for example, a sliding bearing.

[0021] The housing 14 is a bottomed cylindrical body. In this embodiment, the housing 14 is made of a conductive material such as metal. The housing 14 has a housing tubular portion 141, a bracket portion 142, and an inner tubular portion 143. The housing tubular portion 141 is cylindrical and extends in the axial direction, and houses the rotor 11 and the stator 12. The stator 12 is fixed to the inner peripheral surface of the housing tubular portion 141. The bracket portion 142 is annular and surrounds the central axis CA, and is plate-shaped and expands in the radial direction, and covers the other axial end of the housing tubular portion 141. The radial outer end of the bracket portion 142 is connected to the other axial end of the housing tubular portion 141. The inner tubular portion 143 is cylindrical and surrounds the central axis CA, and extends from the radial inner end of the bracket portion 142 in one axial direction. The inner tubular portion 143 holds the bearing 131. An outer ring of the bearing 131 is fixed to the inside of the inner tubular portion 143.

[0022] The bearing holder 15 covers one axial end of the housing tubular portion 141 and holds the bearing 132. In this embodiment, the bearing holder 15 is made of a conductive material such as metal. As described later, the static eliminator 2 is attached to the bearing holder 15. The bearing holder 15 has a cover portion 151 and a holder tubular portion 152. The cover portion 151 is annular and surrounds the central axis CA, and is a plate-like member extending in the radial direction. The cover portion 151 is connected to one axial end of the housing tubular portion 141 and covers one axial end of the housing tubular portion 141. The holder tubular portion 152 is cylindrical and surrounds the central axis CA, and extends in the axial direction from the radial inner end of the cover portion 151. An outer ring of the bearing 132 is fixed to the inner peripheral surface of the holder tubular portion 152. In this embodiment, the static eliminator 2 is further attached to the inner peripheral surface of the holder tubular portion 152.

[0023] The substrate 16 is supported by the inner cylindrical portion 143, and extends radially outward from the radially outer surface of the inner cylindrical portion 143. On the substrate 16, an electric circuit for supplying a drive current to the stator 12 and the like are mounted.

[0024] <1-2. Static eliminator> Next, the static eliminator 2 will be described with reference to Fig. 1 to Fig. 2B. Fig. 2A is a top view showing a configuration example of the static eliminator 2 according to the embodiment. Fig. 2B is a side view of the static eliminator 2 according to the embodiment.

[0025] The static eliminator 2 is electrically connected to the shaft 10 extending in the axial direction along the central axis CA. In this embodiment, the static eliminator 2 is attached to a metallic bearing holder 15 and electrically connected to the bearing holder 15. By providing the motor 1 with the static eliminator 2, even if a potential fluctuation occurs in the shaft 10, the current flowing from the shaft 10 can be released to a conductive member to which the static eliminator 2 is attached (the metallic bearing holder 15 in this embodiment). Therefore, since no current flows through the rolling bearings 131 and 132, the occurrence of electrolytic corrosion caused by the potential fluctuation in the shaft 10 can be prevented.

[0026] The static eliminator 2 has a frame 21, a conductor 22, and a conductor holding portion 23.

[0027] <1-2-1.Frame> The frame 21 extends in the circumferential direction around the central axis CA. As described above, the static eliminator 2 includes the frame 21. The frame 21 is annular and has a plate shape that surrounds the central axis CA and extends in the radial direction. The frame 21 is made of a conductive material such as metal. The frame 21 is disposed radially outward from the shaft 10. The radial inner ends of the frame 21 face each other with a gap in the radial direction. In this embodiment, as shown in FIG. 2A, the radial inner end of the frame 21 faces the entire range of the radial inner end of the frame 21 in the circumferential direction. However, this is not limited to the example, and the radial inner end of the frame 21 may face a part of the range of the radial inner end of the frame 21 in the circumferential direction (for example, see FIG. 3A). In other words, the radial inner end of the frame 21 may face at least a part of the circumferential area of ​​the radial outer surface of the shaft 10 in the radial direction.

[0028] The frame 21 is electrically conductive and fitted inside the holder tube 152. The radial outer end of the frame 21 is attached to the inner circumferential surface of the holder tube 152. This electrically connects the frame 21 to the bearing holder 15. The frame 21 may be attached to the holder tube 152 by press-fitting, brazing using silver solder, or welding. The arrangement of the static eliminator 2 is not limited to this example. For example, the static eliminator 2 may be attached to one axial end of the holder tube 152 or to the lid 151. In the latter case, the holder tube 152 may extend from the radial inner end of the lid 151 to the other axial direction.

[0029] In this embodiment, the planar shape of the frame body 21 is circular as shown in Fig. 2A. For example, the radially outer end portion of the frame body 21 as viewed from the axial direction is circular. However, the planar shape of the frame body 21 is not limited to the example shown in Fig. 2A and may be other than circular, and may be, for example, a polygonal shape such as a triangle or a rectangle (see Fig. 3B), or an ellipse.

[0030] In this embodiment, as shown in FIG. 2A, the radial inner end of the frame body 21 is circular when viewed from the axial direction and extends in the circumferential direction along the radial outer side surface of the shaft. Furthermore, the radial interval between the radial outer side surface of the shaft 10 and the radial inner end of the frame body 21 is equal in the circumferential direction. However, the radial inner end of the frame body 21 is not limited to this example, and may not have a shape that follows the radial outer side surface of the shaft, and the above interval may not be equal in the circumferential direction. For example, the radial inner end of the frame body 21 may be a polygonal shape such as a triangle, a rectangle, or a hexagon (see FIG. 3C), or an ellipse, when viewed from the axial direction.

[0031] Furthermore, in this embodiment, as shown in FIG. 2A etc., the frame body 21 surrounds the shaft 10. In other words, the radially outer surface of the shaft 10 faces the radially inner end of the frame body 21 in the radial direction over the entire circumference in the circumferential direction. However, this is not limited to the example, and the frame body 21 may have a shape that surrounds a part of the shaft 10. Also, the radially outer surface of the shaft 10 may face the frame body 21 in the radial direction in a part of the circumferential direction, while not facing the frame body 21 in the radial direction in another part of the circumferential direction. For example, the frame body 21 may be in the shape of a circular arc when viewed from the axial direction. (See FIG. 3A)

[0032] <1-2-2. Conductors> The conductor 22 is a member that is elongated and bendable. The conductor 22 is conductive. That is, the conductor 22 is formed using a material that is conductive. The material of the conductor 22 is preferably a material with good sliding properties, and more preferably a material with a low coefficient of friction. The material of the conductor 22 can be, for example, a composite resin containing a conductive filler such as carbon fiber or metal. Although the conductor 22 is linear in FIG. 2B, it may be strip-shaped as shown in FIG. 4. This can increase the area where the single conductor 22 contacts the shaft 10. Thus, in this embodiment, the conductor 22 is a member that extends in a linear or strip-like shape.

[0033] <1-2-3. Conductor holding part> The conductor holding portion 23 holds the conductor 22. The conductor holding portion 23 has a plurality of first column portions 231. Each of the first column portions extends in the axial direction from the frame body 21 and is arranged in the circumferential direction. The first column portions 231 are conductive. In this embodiment, the same conductor 22 is wound around all of the first column portions 231. However, this is not limited to the example, and the same conductor 22 may be wound around some of the first column portions 231. In other words, it is sufficient that the same conductor 22 is wound around at least two first column portions 231. Between the first column portions 231 adjacent to each other along the same conductor 22, the conductor 22 contacts the shaft 10.

[0034] In the static eliminator 2, the conductor 22 in contact with the shaft 10 is wound around at least two first columnar portions 231. In addition, the frame body 21, the first columnar portion 231 extending from the frame body 21 in the axial direction, and the frame body 21 each have electrical conductivity. Therefore, the static eliminator 2 can electrically connect the shaft 10 to the frame body 21 via the conductor 22 and the first columnar portion 231. Therefore, even if a potential fluctuation occurs in the shaft 10, a current flows from the shaft 10 to the conductor 22, the first columnar portion 231, and the frame body 21 in that order, and the potential fluctuation in the shaft 10 is immediately eliminated. Therefore, problems caused by the potential fluctuation in the shaft 10 can be eliminated.

[0035] For example, in a PWM-controlled motor, so-called electrolytic corrosion is likely to occur due to potential fluctuations occurring in the shaft. Electrolytic corrosion is a phenomenon that occurs when a current that flows from a shaft to a rolling bearing (for example, a ball bearing, a roller bearing, etc.) discharges in the rolling bearing, damaging the rolling bearing. When electrolytic corrosion occurs, for example, so-called fluting occurs, in which the bearing surfaces of the outer and inner rings on which the rolling members (bearing balls, bearing rollers, etc.) roll are damaged in a wavy shape. On the other hand, in the static eliminator 2 described above, the shaft 10 comes into contact with the conductor 22, so that the current flowing from the shaft 10 can be released to a conductive member (for example, a metallic bearing holder 15, etc.) to which the frame 21 is attached. Therefore, no current flows through the rolling bearings 131 and 132, and the occurrence of the above-mentioned electrolytic corrosion can be prevented.

[0036] In addition, since the wire- or band-shaped conductor 22 is wound around at least two first column sections 231 extending in the axial direction, the conductor 22 can be easily attached. Therefore, the static eliminator 2 that solves the problem caused by the potential fluctuation in the shaft 10 can be efficiently assembled.

[0037] Moreover, the conductor 22 has a predetermined elasticity in the direction in which the conductor 22 extends. For example, between the first pillars 231 adjacent along the same conductor 22, the conductor 22 can bend radially outward while maintaining tension. For example, when the conductor 22 contacts the radially outer surface of the shaft 10, the portion of the conductor 22 that contacts the shaft 10 bends radially outward. Therefore, when viewed from a direction from one of the first pillars 231 adjacent along the same conductor 22 to the other, the portion of the conductor 22 between the adjacent first pillars 231 is radially outward from the adjacent first pillars 231. In this way, for example, the conductor 22 stretched between the first pillars 231 can be pressed against the shaft 10 to come into contact with it. Therefore, it is easier to maintain contact between the conductor 22 and the shaft 10, and the contact area between them can be increased. Therefore, it is possible to ensure a conductive path between the conductor 22 and the shaft 10, and improve the conductivity between them.

[0038] The conductor holding portion 23 further includes a first flange 232. The first flange 232 extends from the first columnar portion 231 at least radially outward. The first flange 232 is disposed closer to the tip of the first columnar portion 231 than the conductor 22 wound around the first columnar portion 231, and is disposed at the tip of the first columnar portion 231 in this embodiment. Preferably, the first flange 232 further extends from the first columnar portion 231 in the circumferential direction. By disposing the first flange 232, the wound conductor 22 is less likely to come off the first columnar portion 231. Therefore, the conductor holding portion 23 can hold the conductor 22 more reliably.

[0039] <1-2-4. Fixed part> Next, preferably, the static eliminator 2 further includes a fixing portion 24. The fixing portion 24 is disposed in at least one conductor holding portion 23 and fixes the conductor 22 to the conductor holding portion 23. In detail, the fixing portion 24 fixes the conductor 22 to at least one of the first column portion 231 and the first flange portion 232. In this manner, the conductor 22 can be fixed to the conductor holding portion 23 in at least one conductor holding portion 23, so that even if the conductor 22 wound around the first column portion 231 in at least one conductor holding portion 23 breaks, it is possible to prevent the conductor 22 from coming off the first column portion 231.

[0040] More preferably, the fixing portion 24 is conductive. That is, a conductive material is used for the fixing portion 24. In this way, the fixing portion 24 can be used as a part of the conductive path between the conductor 22 and the first column portion 231. The conductivity between the conductor 22 and the first column portion 231 can be improved. For the fixing portion 24, a composite resin containing a conductive filler such as a metal, solder, a brazing material such as silver brazing, or the like can be used. In this embodiment, for example, an epoxy resin containing silver powder is used.

[0041] It should be noted that the above examples do not exclude a configuration in which the fixing portion 24 is not disposed on the first pillar portion 231.

[0042] <1-2-5. Other forms> In this embodiment, as shown in Figures 2A and 2B, three first pillars 231 are arranged on one axial end face of the frame 21. However, the number of first pillars 231 is not limited to this example, and may be any number other than three (see Figures 5A and 5B).

[0043] In addition, in this embodiment, as shown in FIG. 2A, the first columnar portion 231 around which the same conductor 22 is wound is arranged to surround the shaft 10. Therefore, the same conductor 22 is wound around the shaft 10. In other words, the shaft 10 is arranged inside the wound conductor 22 when viewed from the axial direction. However, without being limited to this example, the first columnar portion 231 around which the same conductor 22 is wound may be arranged at a position radially opposed to a partial range in the circumferential direction of the radially outer side surface of the shaft 10. In other words, the same conductor 22 may be wound around the first columnar portion 231 arranged in a partial range in the circumferential direction of the radially inner end portion of the frame body 21. In this case, the shaft 10 in contact with the conductor 22 may be arranged outside the wound conductor 22. (For example, see FIG. 3A.)

[0044] In this embodiment, as shown in FIG. 2A, the conductor 22 is wound around all the first column portions 231. However, this is not limited to the example, and the same conductor 22 may be wound around some of the first column portions 231. In this case, other same conductors 22 may be wound around other parts of the first column portions 231. FIG. 6 shows an example of a configuration in which different conductors 22 are wound around different first column portions 231. In FIG. 6, the different conductors 22 are wound around every other different first column portion 231 among the six first column portions 231 arranged in the circumferential direction. In other words, some of the first column portions 231 around which some of the conductors 22 are wound are alternately arranged with some of the first column portions 231 around which other parts of the conductors 22 are wound. In this way, some of the conductors 22 may be wound around some of the first columnar portions 231 that are located at the same axial position to surround the shaft 10. Also, other of the conductors 22 may be wound around some of the remaining first columnar portions 231 that are located at the same axial position to surround the shaft 10. Also, in the circumferential direction, the above-mentioned first columnar portions 231 may be arranged alternately with the above-mentioned remaining first columnar portions 231 at a predetermined number of positions (one in FIG. 6). In this way, the area of ​​contact between the shaft 10 and the conductors 22 in the circumferential direction increases, so that the conductive path between the shaft 10 and the frame body 21 can be made thicker. Also, even if some of the conductors 22 are cut and come off some of the first columnar portions 231, the other conductors 22 are wound around some of the remaining first columnar portions 231, so that the conductive path between the shaft 10 and the frame body 21 can be maintained.

[0045] In this embodiment, as shown in FIG. 2B, the first columnar portion 231 is disposed only on one axial end surface of the frame body 21. However, the first columnar portion 231 is not limited to this example, and may be disposed on both axial end surfaces of the frame body 21. FIG. 7 is a side view showing a modified arrangement of the first columnar portion 231. The static eliminator 2 has a plurality of conductors 22. As shown in FIG. 7, some of the first columnar portions 231 and some of the conductors 22 may be disposed on one axial end surface of the frame body 21. Furthermore, other parts of the first columnar portions 231 and other parts of the conductors 22 may be disposed on the other axial end surface of the frame body 21. In this way, since more conductors 22 can be disposed side by side in the axial direction, the conductive path of the current flowing from the shaft 10 to the first columnar portion 231 via the conductors 22 can be further thickened. Therefore, it becomes easier to prevent problems caused by potential fluctuations in the shaft 10.

[0046] In this embodiment, as shown in Fig. 2B, the same conductor 22 is wound once around multiple first columnar portions 231. However, the conductor 22 is not limited to the above example. Fig. 8A is a side view showing a modified example of the winding of the conductor 22. Fig. 8B is a side view showing another modified example of the winding of the conductor 22.

[0047] 8A, the same conductor 22 may be wound multiple times around at least two first pillar portions 231. This can make the conductive path of the current flowing from the shaft 10 to the first pillar portion 231 via the conductor 22 thicker. This makes it easier to prevent problems caused by potential fluctuations in the shaft 10.

[0048] Furthermore, multiple conductors 22 may be wound around at least two first pillar portions 231. In other words, multiple conductors 22 may be wound around the same first pillar portion 231. This makes it possible to make the conductive path of the current flowing from the shaft 10 to the first pillar portion 231 via the conductors 22 thicker. This makes it easier to prevent problems caused by potential fluctuations in the shaft 10.

[0049] Furthermore, as shown in FIG. 8B, adjacent conductors 22 in a direction perpendicular to the direction in which the conductors 22 extend may be entangled with each other. In other words, a plurality of conductors 22 wound around the same first columnar portion 231 may be entangled with each other. By entangling the conductors 22 with each other, the strength (e.g., tensile strength, etc.) of the conductors 22 can be improved. Furthermore, even if a part of the entangled conductors 22 between adjacent first columnar portions 231 along the same conductor 22 is cut, the cut conductor 22 is entangled with the other conductors 22, and therefore is unlikely to come off the first columnar portion 231 or separate from the shaft 10. Therefore, even if a part of the conductor 22 is cut, the electrical connection between the shaft 10 and the conductor 22 can be maintained.

[0050] 2. Modifications of the embodiment Next, first to third modified examples of the embodiment will be described. In the following, in each modified example, the configuration different from the above-mentioned embodiment and other modified examples will be described. In each modified example, the same components as those in the above-mentioned embodiment and other modified examples are given the same reference numerals, and the description thereof may be omitted.

[0051] <2-1. First modified example> A static eliminator 2 according to a first modified example will be described with reference to Fig. 9. Fig. 9 is a side view showing a configuration example of the static eliminator 2 according to the first modified example. As shown in Fig. 9, in the first modified example, the frame 21 has a plurality of plate frames 211 stacked at intervals in the axial direction. Each plate frame 211 is annular and surrounds the central axis CA, and is a plate-like shape extending in the radial direction. Note that the number of plate frames 211 is three in Fig. 9, but is not limited to the example shown in Fig. 9, and may be a number other than three.

[0052] In Fig. 9, all the first columnar portions 231 and all the conductors 22 are arranged between the plate frames 211. One axial end of the first columnar portions 231 is connected to the other axial end face of the plate frame 211 on one axial side. The other axial end of the first columnar portions 231 is connected to one axial end face of the plate frame 211 on the other axial side. The conductors 22 are wound around the first columnar portions 231 arranged between the same plate frames 211.

[0053] 9, some of the first columnar portions 231 and some of the conductors 22 may be arranged between the plate frames 211. The remaining first columnar portions 231 may be arranged on at least one of the axial one end face of the plate frame 211 arranged on the most axial one side and the axial other end face of the plate frame 211 arranged on the most axial other side, as in the same manner as in Figs. 2B and 7, for example. The remaining conductors 22 may be wound around the first columnar portions 231 arranged on at least one of the above-mentioned faces.

[0054] That is, at least a portion of the first column portions 231 and at least a portion of the conductors 22 may be disposed between axially adjacent plate frames 211. In this manner, more conductors 22 can be disposed side by side in the axial direction, so that the electric path of the current flowing from the shaft 10 to the first column portions 231 via the conductors 22 can be made wider. This makes it easier to prevent problems caused by potential fluctuations in the shaft 10. Also, because at least a portion of the conductors 22 are disposed between the plate frames 211, these conductors 22 can be prevented from coming loose in the axial direction.

[0055] <2-2. Second modified example> Next, a static eliminator 2 according to a second modified example will be described with reference to Fig. 10A to Fig. 10C. Fig. 10A to Fig. 10C show a configuration example of the static eliminator 2 according to the second modified example. Fig. 10A is a top view showing the configuration example of the static eliminator 2 according to the second modified example. Fig. 10B is a side view of the static eliminator 2 according to the second modified example. Fig. 10C is a top view showing an example of a case where the conductor 22 is broken in the second modified example.

[0056] The static eliminator 2 according to the second modification further includes a clamping section 25. The clamping section 25 has a second column section 251 extending from the frame body 21 in the axial direction. In FIG. 10A, two second column sections 251 are arranged in the vicinity of each first column section 231. The second column sections 251 are arranged on both circumferential sides of the first column section 231 for each first column section 231, and are aligned with the first column section 231 in the circumferential direction. However, without being limited to the example of FIG. 10A, the number of second column sections 251 arranged in the vicinity of each first column section 231 may be one or more than two. In addition, at least one second column section 251 may be arranged in a direction perpendicular to the axial direction for each first column section 231, and may be arranged, for example, on the radially outer side of the first column section 231.

[0057] In other words, the second column section 251 only needs to be adjacent to at least one first column section 231 in a direction perpendicular to the axial direction, with the conductor 22 sandwiched between them. In this way, the conductor 22 can be fixed by being sandwiched between the first column section 231 and the second column section 251. Therefore, even if the wound conductor 22 breaks as shown in Fig. 10C, the conductor 22 is unlikely to come off the first column section 231 or separate from the shaft 10. Therefore, the electrical connection between the shaft 10 and the first column section 231 via the conductor 22 can be maintained.

[0058] Preferably, the clamping portion 25 further has a second flange 252. The second flange 252 spreads from the second pillar portion 251 toward at least the first pillar portion 231 in a direction perpendicular to the axial direction. The second flange 252 is disposed closer to the tip of the first pillar portion 231 than the conductor 22 wound around the first pillar portion 231, and is disposed at the tip of the second pillar portion 251 in FIG. 10B. This makes it even more difficult for the wound conductor 22 to come off between the first pillar portion 231 and the second pillar portion 251. Therefore, the conductor 22 can be more reliably held between them.

[0059] Furthermore, in the second modified example, preferably, the fixing portion 24 is further arranged in at least one of the clamping portions 25, and fixes the conductor 22 to at least one of the second pillar portion 251 and the second flange portion 252. In this way, the conductor 22 can be fixed to the clamping portion 25 in at least one of the clamping portions 25, so that the conductor 22 clamped between the first pillar portion 231 can be held more reliably. However, this example does not exclude a configuration in which the fixing portion 24 is not arranged in the clamping portion 25.

[0060] <2-3.Third modified example> Next, a static eliminator 2 according to a third modified example will be described with reference to Fig. 11. Fig. 11 is a side view showing an example of the configuration of the static eliminator 2 according to the third modified example.

[0061] The motor 1 includes a bearing holder 15 that holds a rolling bearing 132. In the third modification, the frame 21 of the static eliminator 2 is part of the bearing holder 15, and is a lid portion 151 in FIG. 11. The conductor holders 23 are disposed at the radially inner end of the lid portion 151 that faces the shaft 10 in the radial direction, and are aligned in the circumferential direction. The first pillar portion 231 protrudes from the lid portion 151 in the axial direction.

[0062] In this way, the conductor holding part 23 can be disposed in the bearing holder 15 of the motor 1, and the static eliminator 2 can be integrated with the bearing holder 15. This allows the number of parts of the motor 1 to be reduced, and therefore the number of assembly steps for the motor 1 to be reduced.

[0063] <3.Other> The embodiments of the present invention have been described above. Note that the scope of the present invention is not limited to the above-described embodiments. The present invention can be implemented by adding various modifications to the above-described embodiments without departing from the spirit of the invention. Furthermore, the matters described in the above-described embodiments can be appropriately combined in any manner as long as no contradiction occurs. [Industrial Applicability]

[0064] The present invention is useful in devices for grounding shafts. [Explanation of symbols]

[0065] REFERENCE SIGNS LIST 1 motor, 10 shaft, 11 rotor, 12 stator, 131, 132 bearing, 14 housing, 141 housing cylinder, 142 bracket portion, 143 inner cylinder, 15 bearing holder, 151 cover portion, 152 holder cylinder portion, 16 circuit board, 2 static eliminator, 21 frame, 211 plate frame, 22 conductor, 23 conductor holding portion, 231 first pillar portion, 232 first flange portion, 24 fixing portion, 25 clamping portion, 251 second pillar portion, 252 second flange portion, CA central axis

Claims

1. A static eliminator electrically connected to a shaft extending axially along a central axis, A frame body extending in a circumferential direction about the central axis; A conductor extending in a linear or strip shape; A conductor holder that holds the conductor; Equipped with The frame is disposed radially outward from the shaft, The radially inner end of the frame is radially opposed to at least a portion of a circumferential region of the radially outer surface of the shaft, The conductor holding portion has a plurality of first pillar portions extending axially from the frame body, The first pillar portions are arranged in a circumferential direction, the frame body and the first columnar portion each have electrical conductivity, The same conductor is wound around at least two of the first pillar portions, Between the first pillar portions adjacent to each other along the same conductor, the conductor contacts the shaft, A static eliminator, wherein the shaft is disposed inside the wound conductor when viewed in the axial direction.

2. A static elimination device electrically connected to a shaft extending axially along a central axis, A frame body extending in a circumferential direction about the central axis; A conductor extending in a linear or strip shape; A conductor holder that holds the conductor; Equipped with The frame is disposed radially outward from the shaft, The radially inner end of the frame is radially opposed to at least a portion of a circumferential region of the radially outer surface of the shaft, The conductor holding portion has a plurality of first pillar portions extending axially from the frame body, The first pillar portions are arranged in a circumferential direction, the frame body and the first columnar portion each have electrical conductivity, The same conductor is wound around at least two of the first pillar portions, Between the first pillar portions adjacent to each other along the same conductor, the conductor contacts the shaft, A static eliminator, wherein the same conductor is wound multiple times around the at least two first column portions.

3. The static eliminator according to claim 1 or 2, wherein a plurality of the conductors are wound around the at least two first columnar portions.

4. The static eliminator according to claim 2 , wherein the conductors adjacent to each other in a direction perpendicular to a direction in which the conductors extend are entangled with each other.

5. Some of the conductors are wound around some of the first columnar portions that are located at the same axial position to surround the shaft, The other part of the conductor is wound around the remaining part of the first column parts that are located at the same axial position, and surrounds the shaft, The static eliminator according to claim 1 , wherein the first column portions and the remaining first column portions are arranged alternately at intervals of a predetermined number in a circumferential direction.

6. A static elimination device electrically connected to a shaft extending axially along a central axis, A frame body extending in a circumferential direction about the central axis; A conductor extending in a linear or strip shape; A conductor holder that holds the conductor; Equipped with The frame is disposed radially outward from the shaft, The radially inner end of the frame is radially opposed to at least a portion of a circumferential region of the radially outer surface of the shaft, The conductor holding portion has a plurality of first pillar portions extending axially from the frame body, The first pillar portions are arranged in a circumferential direction, the frame body and the first columnar portion each have electrical conductivity, The same conductor is wound around at least two of the first pillar portions, Between the first pillar portions adjacent to each other along the same conductor, the conductor contacts the shaft, The frame body has a plurality of plate frames stacked at intervals in the axial direction, At least a portion of the first column portion and at least a portion of the conductor are disposed between the plate frames.

7. A part of the first columnar portions and a part of the conductors are disposed on one axial end surface of the frame body, The static eliminator according to claim 1 , wherein another portion of the first columnar portions and another portion of the conductors are disposed on another axial end face of the frame.

8. The static eliminator according to claim 1 , wherein the conductor holding portion further includes a first flange portion extending outward at least in a radial direction from the first column portion.

9. A static elimination device electrically connected to a shaft extending axially along a central axis, A frame body extending in a circumferential direction about the central axis; A conductor extending in a linear or strip shape; A conductor holder that holds the conductor; Equipped with The frame is disposed radially outward from the shaft, The radially inner end of the frame is radially opposed to at least a portion of a circumferential region of the radially outer surface of the shaft, The conductor holding portion has a plurality of first pillar portions extending axially from the frame body, The first pillar portions are arranged in a circumferential direction, the frame body and the first columnar portion each have electrical conductivity, The same conductor is wound around at least two of the first pillar portions, Between the first pillar portions adjacent to each other along the same conductor, the conductor contacts the shaft, A clamping portion having a second pillar portion extending axially from the frame body, The second columnar portion is adjacent to at least one of the first columnar portions in a direction perpendicular to the axial direction, with the conductor sandwiched between the second columnar portion and at least one of the first columnar portions.

10. The static eliminator according to claim 9 , wherein the clamping portion further includes a second flange portion that spreads out from the second column portion toward at least the first column portion in a direction perpendicular to the axial direction.

11. A static elimination device electrically connected to a shaft extending axially along a central axis, A frame body extending in a circumferential direction about the central axis; A conductor extending in a linear or strip shape; A conductor holder that holds the conductor; Equipped with The frame is disposed radially outward from the shaft, The radially inner end of the frame is radially opposed to at least a portion of a circumferential region of the radially outer surface of the shaft, The conductor holding portion has a plurality of first pillar portions extending axially from the frame body, The first pillar portions are arranged in a circumferential direction, the frame body and the first columnar portion each have electrical conductivity, The same conductor is wound around at least two of the first pillar portions, Between the first pillar portions adjacent to each other along the same conductor, the conductor contacts the shaft, The static eliminator further comprises a fixing portion disposed on at least one of the conductor holding portions and fixing the conductor to the conductor holding portion.

12. The static eliminator according to claim 11 , wherein the fixing portion is conductive.

13. The static eliminator according to claim 1 , wherein the conductor is capable of bending radially outward while maintaining tension between the first pillar portions adjacent to each other along the same conductor.

14. The static eliminator according to any one of claims 1 to 13, The shaft extends axially along the central axis; a rolling bearing that supports the shaft so as to be rotatable about the central axis; A motor comprising:

15. 15. The motor of claim 14, wherein when viewed from a direction from one of the adjacent first column portions toward the other along the same conductor, a portion of the conductor between the adjacent first column portions is located radially outward from the adjacent first column portions.

16. A bearing holder for holding the rolling bearing is further provided. The motor according to claim 14 or 15, wherein the frame of the static eliminator is a part of the bearing holder.

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