Rotor
The rotor design with magnets attracted to magnetic body surfaces in openings enhances productivity by improving assembly workability and maintaining motor performance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- MINEBEAMITSUMI INC
- Filing Date
- 2024-11-08
- Publication Date
- 2026-05-20
AI Technical Summary
The productivity of rotors with internal magnets needs improvement.
A rotor design featuring a plurality of openings along the rotation axis, with magnets positioned in these openings and a magnetic body between them, where the magnets are magnetically attracted to specific surfaces of the magnetic body, creating regions of higher magnetic resistance to enhance assembly and reduce protrusion during assembly.
This design improves assembly workability by attracting magnets to the magnetic body surfaces, suppressing protrusion and maintaining motor characteristics like torque.
Smart Images
Figure 2026083960000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a rotor.
Background Art
[0002] As a rotor used in a motor, one having a magnet (permanent magnet) inside is known. For example, Patent Document 1 discloses a rotor for a brushless motor, in which the magnet is fitted into a through hole.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In a rotor having a magnet inside, an improvement in productivity is required. The present invention takes an improvement in the productivity of the rotor as an example of the problem.
Means for Solving the Problems
[0005] An example of the present invention is a rotor comprising a plurality of openings extending in the direction of rotation axis, a plurality of magnets disposed in the plurality of openings, and a magnetic body disposed between the plurality of magnets in the circumferential direction, wherein the magnetic body comprises a first side surface, a second side surface, and an intermediate portion between the first side surface and the second side surface, the plurality of magnets include a first magnet on the first side surface side of the magnetic body and a second magnet on the second side surface side of the magnetic body, the first magnet and the second magnet repel each other magnetically in the circumferential direction via the magnetic body, a region having higher magnetic resistance than the magnetic body is formed between the first magnet and the second magnet in the circumferential direction, the region extends in the direction of rotation axis, the first magnet is magnetically attracted to the first side surface of the magnetic body, and the second magnet is magnetically attracted to the second side surface of the magnetic body. [Brief explanation of the drawing]
[0006] [Figure 1] This is a cross-sectional view along the rotation axis of a motor equipped with a rotor according to the first embodiment, and is a cross-sectional view of BB in Figure 2. [Figure 2] This is a cross-sectional view along the radial direction of a motor equipped with a rotor according to the first embodiment, and is the AA cross-sectional view in Figure 1. [Figure 3] This is a partial cross-sectional view along the radial direction of a rotor according to the first embodiment. [Figure 4] This is an enlarged cross-sectional perspective view showing a portion of the rotor core of the rotor according to the first embodiment. [Figure 5] This is a radial cross-sectional view of a motor equipped with a rotor according to a second embodiment. [Figure 6] This is a partial cross-sectional view of the rotor along the radial direction according to the second embodiment. [Figure 7] This is an enlarged cross-sectional perspective view showing a portion of the rotor according to the second embodiment. [Modes for carrying out the invention]
[0007] In describing each embodiment of the present invention, for the sake of convenience, the direction along the rotation axis X (the central axis of the shaft 130) (the direction in which the rotation axis X extends) is referred to as the axial direction or rotation axis direction. In the rotation axis direction, the direction of arrow a in Figure 1 is referred to as one side, and the direction of arrow b, which is the opposite direction, is referred to as the other side. Furthermore, the direction of arrow cd perpendicular to the rotation axis X is referred to as the radial direction, the direction of arrow c moving away from the rotation axis X is referred to as the outer side or one side in the radial direction, and the direction of arrow d approaching the rotation axis X is referred to as the inner side or the other side in the radial direction. In addition, the direction of rotation around the rotation axis X is referred to as the circumferential direction. In a certain member or part, the outer surface in the radial direction (direction of arrow c) may be referred to as the outer circumferential surface, and the inner surface in the radial direction (direction of arrow d) may be referred to as the inner circumferential surface. In a certain member or part, the outer part in the radial direction (direction of arrow c) may be referred to as the outer circumferential part, and the inner part in the radial direction (direction of arrow d) may be referred to as the inner circumferential part.
[0008] [First Embodiment] Hereinafter, a first embodiment, which is an example of the present invention, will be described with reference to the drawings. Figure 1 is a cross-sectional view of the motor 100 along the rotation axis X, and is the BB cross-sectional view in Figure 2. Figure 2 is a cross-sectional view of the motor 100 along the radial direction, and is the AA cross-sectional view in Figure 1. The motor 100 is an example of a motor equipped with the rotor 160 according to this embodiment. The rotor 160 according to this embodiment may be provided in a motor having other configurations.
[0009] As shown in Figure 1, the motor 100 comprises a housing 110, a cover 120, and a shaft 130. The motor 100 has a generally cylindrical shape. However, the motor 100 may have other shapes. The housing 110 comprises a housing body 111, a flange 112, and a bottom 113. The housing body 111 has a generally cylindrical shape. However, the housing body 111 may have other shapes. The flange 112 is a portion that extends radially outward (arrow c) from one end (direction a) in the rotation axis direction of the housing body 111. The bottom 113 is a portion that covers part or all of the other side (direction b) in the rotation axis direction of the housing body 111. The cover 120 has a generally disc-shaped plate portion (plate-like portion) 121. The shape of the outer circumference of the plate portion 121 corresponds to the shape of the outer circumference of the flange 112 of the housing 110 (shape of the outer edge in the radial direction). The outer periphery of the plate portion 121 of the lid 120 is connected to the flange 112 of the housing 110 by fastening members (not shown), such as a plurality of bolts, which are inserted in the direction of the rotation axis.
[0010] In the radial direction, a circular hole 120h is formed on the inside of the lid 120 (in the direction of arrow d). The hole 120h is formed coaxially with the housing body 111 and the shaft 130. The hole 120h penetrates the plate portion 121 of the lid 120 in the direction of the rotation axis. As shown in Figure 1, in the radial direction, a cylindrical projection 122 is provided on the outside of the hole 120h of the lid 120 (in the direction of arrow c). The projection 122 protrudes to the other side in the direction of the rotation axis (in the direction of arrow b). The projection 122 is provided coaxially with the circular hole 120h. The projection 122 holds the first bearing 141, which will be described later.
[0011] As shown in Figure 1, the shaft 130 is a substantially cylindrical or cylindrical member as a whole. In the direction of rotation axis, the shaft 130 extends from near the bottom 113 of the housing 110 to one side (direction of arrow a) of the lid 120. The shaft 130 passes through the hole 120h of the lid 120 and protrudes to one side (direction of arrow a) in the direction of rotation axis.
[0012] The shaft 130 has one end 131 on one side in the direction of rotation axis (direction of arrow a) and the other end 134 on the other side (direction of arrow b). The shaft 130 may have teeth (concave or convex) on the outer circumferential surface of one end 131 for extracting driving force to the outside. In the illustrated embodiment, the radial dimensions (diameters) of the outer circumferential surfaces of one end 131 and the other end 134 of the shaft 130 are slightly smaller than the dimensions (diameters) of the other parts of the shaft 130. However, the dimensions (diameters) of one end 131 or the other end 134 of the shaft 130 may be the same as the dimensions (diameters) of the other parts of the shaft 130, or they may be larger than the dimensions (diameters) of the other parts of the shaft 130. As shown in the illustration, the shaft 130 may have an annular portion 132 on one side of the central part in the direction of rotation axis (direction of arrow a) which has a larger radial dimension (diameter) of the outer circumferential surface than the other parts.
[0013] The motor 100 has a first bearing 141. In the radial direction, the first bearing 141 is located on the outside (in the direction of arrow c) of one end 131 of the shaft 130. The first bearing 141 is a ball bearing comprising an inner ring 141i, an outer ring 141o, and rolling elements. The first bearing 141 is not limited to a ball bearing, and may be various other types of bearings, such as a sleeve bearing. The first bearing 141 may also be another form of ball bearing having rolling elements and an outer ring fitted into recesses on the outer surface of the shaft.
[0014] The inner ring 141i of the first bearing 141 is bonded or press-fitted to the outer circumferential surface of one end 131 of the shaft 130. The inner ring 141i of the first bearing 141 is fixed to the shaft 130 and rotates together with the shaft 130 around the rotation axis X. In the direction of rotation, the inner ring 141i of the first bearing 141 is in contact with the annular portion 132 of the shaft 130 from one side (direction of arrow a). This positions the shaft 130 in the direction of rotation. The outer ring 141o of the first bearing 141 is bonded or press-fitted to the inner circumferential surface of the projection 122 of the cover 120. This holds the outer ring 141o of the first bearing 141 to the projection 122 of the cover 120. With this configuration, the first bearing 141 rotatably supports the shaft 130 relative to the cover 120.
[0015] The motor 100 has a second bearing 142. In the radial direction, the second bearing 142 is located on the outside (in the direction of arrow c) of the other end 134 of the shaft 130. The second bearing 142 is a ball bearing comprising an inner ring 142i, an outer ring 142o, and rolling elements. The second bearing 142 is not limited to a ball bearing, and may be various other types of bearings, such as a sleeve bearing. The second bearing 142 may also be another form of ball bearing having rolling elements and an outer ring fitted into recesses on the outer surface of the shaft.
[0016] The inner ring 142i of the second bearing 142 is bonded or press-fitted to the outer circumferential surface of the other end 134 of the shaft 130. The inner ring 142i of the second bearing 142 is fixed to the shaft 130 and rotates integrally with the shaft 130 around the rotation axis X. The inner circumferential surface of the bottom 113 of the housing 110 is provided with a cylindrical retaining portion 113a that protrudes to one side (direction of arrow a) in the rotation axis direction. The outer ring 142o of the second bearing 142 is bonded or press-fitted to the inner circumferential surface of the retaining portion 113a of the housing 110. As a result, the outer ring 142o of the second bearing 142 is held by the retaining portion 113a of the housing 110. With this configuration, the second bearing 142 rotatably supports the shaft 130 relative to the housing 110.
[0017] As shown in FIG. 1, the rotor 160 is disposed between the annular portion 132 and the other end portion 134 of the shaft 130 in the rotational axis direction. The inner peripheral surface of the annular portion 164 of the rotor 160, which will be described later, is fixed to the outer peripheral surface of the shaft 130. The shaft 130 rotates integrally with the rotor 160.
[0018] The motor 100 has a stator 150. As shown in FIGS. 1 and 2, the stator 150 is supported inside (in the direction of arrow d) in the radial direction of the housing body 111 of the housing 110. The stator 150 is disposed so as to face the rotor 160 in the radial direction. In the radial direction, the stator 150 is disposed outside (in the direction of arrow c) the rotor 160. The stator 150 surrounds the rotor 160 from the outside in the radial direction.
[0019] As shown in FIG. 2, the stator 150 has a stator core (magnetic body) 151 and a coil 152. The stator core 151 is a laminate in which a plurality of magnetic bodies such as silicon steel sheets are stacked in the rotational axis direction. The stator core 151 has an annular portion 154 and a plurality of teeth (magnetic pole portions) 153. The number of teeth in the plurality of teeth 153 is 12 in FIG. 2, but any other number may be used as long as the motor functions. The annular portion 154 is disposed coaxially with the shaft 130. The plurality of teeth 153 extend from the annular portion 154 toward the shaft 130. The plurality of teeth 153 are formed at equal intervals in the circumferential direction. The plurality of teeth 153 face the rotor 160. The coil 152 is wound around each of the plurality of teeth 153. The stator core 151 and the coil 152 are insulated by an insulator (not shown) formed of an insulator.
[0020] When the motor 100 operates and current flows through the coil 152, due to the electromagnetic action between the stator 150 and the rotor 160, the rotor 160 and the shaft 130 fixed to the rotor 160 rotate integrally. The driving force of the motor 100 can be taken out, for example, from one end portion 131 of the shaft 130.
[0021] As shown in FIG. 2, the rotor 160 includes a plurality of magnets 161, another plurality of magnets 162 different from the plurality of magnets 161, and a rotor core 163. For convenience, the plurality of magnets 161 may be referred to as "a plurality of outer magnets 161", and the plurality of magnets 162 may be referred to as "a plurality of inner magnets 162". The number of magnets in the plurality of outer magnets 161 and the plurality of inner magnets 162 is 20 each in FIG. 2, but may be any other number as long as it functions as a motor. The rotor core 163 is formed, for example, from a plurality of magnetic plates laminated in the rotational axis direction. The rotor core 163 has an annular portion 164, a plurality of connecting portions 166, 167 extending outward in the radial direction (in the direction of arrow c) from the annular portion 164, and a plurality of magnetic bodies 165 (hereinafter, may also be referred to as "a plurality of magnetic pole pieces 165" for convenience) extending radially at equal intervals in the circumferential direction from the annular portion 164 via the connecting portions 166, 167. The number of magnetic pole pieces in the plurality of magnetic pole pieces 165 is 20 in FIG. 2, but may be any other number as long as it functions as a motor. The plurality of connecting portions 166, 167 connect the annular portion 164 and the plurality of magnetic pole pieces 165.
[0022] The rotor 160 has a plurality of openings 168 extending in the rotational axis direction. Each of the plurality of openings 168 is a space between two adjacent magnetic pole pieces included in the plurality of magnetic pole pieces 165. Each of the plurality of openings 168 has a substantially rectangular cross-section (a cross-section perpendicular to the rotational axis direction). Each of the plurality of outer magnets 161 is a permanent magnet that extends in the rotational axis direction and is substantially rectangular parallelepiped as a whole. Each of the plurality of outer magnets 161 is disposed in each of the plurality of openings 168. In the circumferential direction, each of the plurality of magnetic bodies 165 is disposed between the plurality of outer magnets 161.
[0023] Each of the multiple inner magnets 162 is a permanent magnet that extends in the direction of the rotation axis and is collectively approximately rectangular in shape. In the direction of the rotation axis, the dimensions of each of the multiple inner magnets 162 are the same as or approximately the same as the dimensions of each of the multiple outer magnets 161. In the radial direction, the dimensions of each of the multiple inner magnets 162 are smaller than the dimensions of each of the multiple outer magnets 161. In the radial direction, the multiple inner magnets 162 are positioned between the annular portion 164 and the multiple pole pieces 165. In the radial direction, the multiple inner magnets 162 are positioned inside the multiple outer magnets 161. In the circumferential direction, each of the multiple inner magnets 162 is positioned in the space having a substantially trapezoidal cross-section (a cross-section perpendicular to the direction of the rotation axis) between two adjacent connecting portions of the multiple connecting portions 166, 167. In the radial direction, the multiple inner magnets 162 are positioned outside the annular portion 164 (direction of arrow c) and inside the multiple pole pieces 165 (direction of arrow d).
[0024] The rotor 160 will now be described in more detail with reference to Figures 3 and 4. Figure 3 is an enlarged cross-sectional view of the periphery of one magnetic material 165A (hereinafter sometimes referred to as "magnetic pole piece 165A" for convenience) included in the plurality of magnetic pole pieces 165 in the rotor 160. Figure 4 is an enlarged cross-sectional perspective view of the rotor core 163 showing the magnetic pole piece 165A. In this embodiment, all magnetic materials (magnetic pole pieces) included in the plurality of magnetic pole pieces 165 have the same configuration as magnetic pole piece 165A. However, some of the magnetic materials (magnetic pole pieces) included in the plurality of magnetic pole pieces 165 may have a different configuration from magnetic pole piece 165A.
[0025] As shown in Figure 3, in the circumferential direction, the pole piece 165A comprises a first side surface 165Aa, a second side surface 165Ab, and an intermediate portion 165Ac. In the circumferential direction, the intermediate portion 165Ac is located between the first side surface 165Aa and the second side surface 165Ab. The pole piece 165A has a shape that widens circumferentially towards the radially outward direction (direction of arrow c). The outer circumferential surface of the pole piece 165A is part of a hypothetical cylinder C centered on the axis of rotation X. Note that the outer circumferential surface of the pole piece 165A may have a curved shape, such as part of a perfect circle or part of an ellipse.
[0026] Figure 3 illustrates two magnets included in the multiple outer magnets 161. For convenience, the magnet on the first side surface 165Aa of the pole piece 165A is referred to as the first magnet 161A, and the magnet on the second side surface 165Ab of the pole piece 165A is referred to as the second magnet 161B. The dimensions and shape of the first magnet 161A and the second magnet 161B are substantially the same. In the circumferential direction, the first magnet 161A and the second magnet 161B sandwich the pole piece 165A. That is, in the circumferential direction, the first magnet 161A, the pole piece 165A, and the second magnet 161B are arranged in this order. The first magnet 161A and the second magnet 161B are located radially inward (in the direction of arrow d) from a hypothetical cylinder C centered on the axis of rotation X.
[0027] In the circumferential direction, the first magnet 161A and the second magnet 161B repel each other magnetically via the pole piece 165A. That is, the magnetic pole of the first magnet 161A on the side with the pole piece 165A (the magnetic pole of surface 161Ab) is the same as the magnetic pole of the second magnet 161B on the side with the pole piece 165A (the magnetic pole of surface 161Ba). If the surface 161Ab side of the first magnet 161A is a north pole, then the surface 161Ba side of the second magnet 161B is also a north pole. If the surface 161Ab side of the first magnet 161A is a south pole, then the surface 161Ba side of the second magnet 161B is also a south pole.
[0028] In the circumferential direction, air gaps Ga and Gb are formed between the first magnet 161A and the second magnet 161B, which are regions having higher magnetic resistance than the pole piece 165A. The cross-sectional shape of air gaps Ga and Gb (cross-section perpendicular to the rotation axis direction) is rectangular or approximately rectangular. However, the cross-sectional shape of air gaps Ga and Gb (cross-section perpendicular to the rotation axis direction) may be other shapes, such as curved shapes. In the circumferential direction, air gap Ga is formed between the first magnet 161A and the inner circumferential portion 165Ad of the pole piece 165A. In the circumferential direction, air gap Gb is formed between the second magnet 161B and the inner circumferential portion 165Ad of the pole piece 165A. Air gaps Ga and Gb are located in the innermost portion (direction of arrow d) when the pole piece 165A is virtually divided into three equal parts radially. Air gaps Ga and Gb extend in the direction of the rotation axis. In the direction of rotation axis, both air gaps Ga and Gb extend from one end to the other end of the magnetic pole piece 165. Air may be interposed in air gaps Ga and Gb, or they may be filled with a material such as resin or a metal such as aluminum that has a higher magnetic resistance than the magnetic pole piece 165A. In the radial direction, air gaps Ga and Gb are located outside (in the direction of arrow c) of the connecting portions 166 and 167. In the radial direction, air gaps Ga and Gb are located outside (in the direction of arrow c) of the inner magnets 162A included in the plurality of inner magnets 162.
[0029] In the radial direction, the dimensions of the air gaps Ga and Gb may be, for example, 1 / 2, 1 / 3, or 1 / 4 of the dimensions of the first magnet 161A and the second magnet 161B. In the circumferential direction, the dimensions of the air gaps Ga and Gb may be, for example, 1 / 5, 1 / 8, 1 / 10, or 1 / 12 of the dimensions of the first magnet 161A and the second magnet 161B. One or both of the air gaps Ga and Gb may be formed in multiple locations in the radial direction.
[0030] As shown in Figure 4, a recess 165Ae is formed on the first side surface 165Aa of the pole piece 165A, and a recess 165Af is formed on the second side surface 165Ab. Recesses 165Ae and 165Af are formed on the inner circumference 165Ad of the pole piece 165A. Air gaps Ga and Gb are formed by recesses 165Ae and 165Af, respectively. In the direction of rotation axis, both recesses 165Ae and 165Af extend from one end (direction of arrow a) to the other end (direction of arrow b) of the pole piece 165.
[0031] The first magnet 161A is subjected to a magnetic attractive force F1a between it and the first side surface 165Aa of the pole piece 165A, and a magnetic repulsive force F2a between it and the second magnet 161B. Similarly, the second magnet 161B is subjected to a magnetic attractive force F1b between it and the second side surface 165Ab of the pole piece 165A, and a magnetic repulsive force F2b between it and the first magnet 161A. The magnitudes of the magnetic repulsive forces F2a and F2b between the first magnet 161A and the second magnet 161B are adjusted by the air gaps Ga and Gb. When the attractive forces F1a and F1b exceed the repulsive forces F2a and F2b, the first magnet 161A is attracted to the first side surface 165Aa of the pole piece 165A, and the second magnet 161B is attracted to the second side surface 165Ab of the pole piece 165A.
[0032] As shown in Figure 3, the pole piece 165A is connected to the annular portion 164 by two adjacent connecting portions 166 and 167. The two adjacent connecting portions 166 and 167 connected to the pole piece 165A extend circumferentially toward each other as they move radially outward (in the direction of arrow c), that is, as they approach the pole piece 165A. However, the two adjacent connecting portions 166 and 167 connected to the pole piece 165A may also extend circumferentially toward each other as they move radially outward (in the direction of arrow c), or they may extend while maintaining an equal distance from each other. A space S having a substantially trapezoidal cross-section (a cross-section perpendicular to the direction of the rotation axis) is formed between the two adjacent connecting portions 166 and 167 connected to the pole piece 165A. The inner magnets 162A included in the plurality of inner magnets 162 are arranged in space S between the annular portion 164 and the pole piece 165A. The portion of space S excluding the inner magnet 162A may be filled with a non-magnetic material such as resin or a metal such as aluminum.
[0033] The magnetic pole on the side of the magnetic pole piece 165A of the inner magnet 162A is the same as the magnetic pole on the side of the magnetic pole piece 165A of the first magnet 161A and the magnetic pole on the side of the magnetic pole piece 165A of the second magnet 161B. If the surface 161Ab of the first magnet 161A and the surface 161Ba of the second magnet 161B are north poles, then the magnetic pole piece 165A of the inner magnet 162A is also a north pole. If the surface 161Ab of the first magnet 161A and the surface 161Ba of the second magnet 161B are south poles, then the magnetic pole piece 165A of the inner magnet 162A is also a south pole. In this way, a magnetic force of either a north pole or a south pole is applied to each of the multiple magnetic pole pieces 165, and they are emitted radially outward as a single magnetic flux (in the direction of arrow c). The magnetic poles of the multiple magnetic pole pieces 165 are configured so that north poles and south poles alternate in the circumferential direction.
[0034] In the rotor 160 according to this embodiment, the first magnet 161A is attracted to the first side surface 165Aa of the pole piece 165A, and the second magnet 161B is attracted to the second side surface 165Ab of the pole piece 165A. Therefore, during assembly, the protrusion of the multiple outer magnets 161 is suppressed or prevented, improving workability. The attractive forces F1a and F1b can be adjusted, for example, by the position, shape, and size of the air gaps Ga and Gb. Furthermore, in the rotor 160 according to this embodiment, regions having higher magnetic resistance than the pole piece 165A (air gaps Ga and Gb) are formed between the inner circumference 165Ad of the pole piece 165A and the first magnet 161A in the direction from the pole piece 165A toward the first magnet 161A, and between the inner circumference 165Ad of the pole piece 165A and the second magnet 161B in the direction from the pole piece 165A toward the second magnet 161B. By providing such regions on the inner circumference 165Ad of the pole piece 165A, it is possible to improve workability while suppressing the influence on motor characteristics such as torque.
[0035] [Second Embodiment] Hereinafter, a second embodiment, which is an example of the present invention, will be described with reference to the drawings. Figure 5 is a cross-sectional view of the motor 200 along the radial direction. The motor 200 is an example of a motor equipped with a rotor 260 according to this embodiment. The rotor 260 according to this embodiment may be provided in a motor with other configurations. The motor 200 has the same configuration as the motor 100 described in the first embodiment, except that it is equipped with a rotor 260. The rotor 260 has the same configuration as the rotor 160 described in the first embodiment, except that it is equipped with multiple magnetic materials 265 (hereinafter, for convenience, sometimes referred to as "multiple magnetic pole pieces 265") instead of multiple magnetic materials 165. Hereinafter, members and parts having the same function and configuration as the motor 100 and rotor 160 according to the first embodiment will be denoted by the same reference numerals, and their detailed description will be omitted.
[0036] As shown in Figure 5, the rotor 260 comprises a plurality of magnets 161, a plurality of other magnets 162 distinct from the plurality of magnets 161, and a rotor core 263. For convenience, the plurality of magnets 161 may be referred to as "a plurality of outer magnets 161," and the plurality of magnets 162 as "a plurality of inner magnets 162." In Figure 5, the number of magnets in the plurality of outer magnets 161 and the plurality of inner magnets 162 is 20 each, but any other number may be used as long as it functions as a motor. The rotor core 263 is formed from a plurality of magnetic plates stacked in the direction of the rotation axis. The rotor core 263 has an annular portion 164, a plurality of connecting portions 166, 167 extending radially outward from the annular portion 164 (in the direction of arrow c), and a plurality of magnetic pole pieces 265 extending radially at equal intervals in the circumferential direction from the annular portion 164 via the connecting portions 166, 167. In Figure 5, the number of pole pieces in the multiple pole pieces 265 is 20, but any other number is acceptable as long as it functions as a motor. The multiple connecting parts 166 and 167 connect the annular part 164 to the multiple pole pieces 265.
[0037] The rotor 260 has a plurality of openings 268 extending in the direction of the rotation axis. Each of the plurality of openings 268 is the space between two adjacent pole pieces included in a plurality of pole pieces 265. Each of the plurality of openings 268 has a substantially rectangular cross-section (a cross-section perpendicular to the direction of the rotation axis). Each of the plurality of outer magnets 161 is positioned in each of the plurality of openings 268. In the circumferential direction, each of the plurality of pole pieces 265 is positioned between the plurality of outer magnets 161. In the radial direction, the plurality of inner magnets 162 are positioned outside the annular portion 164 (direction of arrow c) and inside the plurality of pole pieces 265 (direction of arrow d).
[0038] The rotor 260 will now be described in more detail with reference to Figures 6 and 7. Figure 6 is an enlarged cross-sectional view of the periphery of one magnetic material 265A (hereinafter sometimes referred to as "magnetic pole piece 265A" for convenience) included in the plurality of magnetic pole pieces 265 in the rotor 260. Figure 7 is an enlarged cross-sectional perspective view of the periphery of magnetic pole piece 265A in the rotor 260. In this embodiment, all magnetic materials (magnetic pole pieces) included in the plurality of magnetic pole pieces 265 have the same configuration as magnetic pole piece 265A. However, some of the magnetic materials (magnetic pole pieces) included in the plurality of magnetic pole pieces 265 may have a different configuration from magnetic pole piece 265A.
[0039] As shown in Figure 6, in the circumferential direction, the pole piece 265A comprises a first side surface 265Aa, a second side surface 265Ab, and an intermediate portion 265Ac. In the circumferential direction, the intermediate portion 265Ac is located between the first side surface 265Aa and the second side surface 265Ab. The pole piece 265A has a shape that widens circumferentially towards the radially outward direction (direction of arrow c). The outer circumferential surface of the pole piece 265A is part of a hypothetical cylinder C centered on the axis of rotation X. Note that the outer circumferential surface of the pole piece 265A may have a curved shape, such as part of a perfect circle or part of an ellipse.
[0040] Figure 6 illustrates two magnets included in the multiple outer magnets 161. For convenience, the magnet on the first side 265Aa of the pole piece 265A is referred to as the first magnet 161A, and the magnet on the second side 265Ab of the pole piece 265A is referred to as the second magnet 161B. The dimensions and shape of the first magnet 161A and the second magnet 161B are substantially the same. In the circumferential direction, the first magnet 161A and the second magnet 161B sandwich the pole piece 265A. That is, in the circumferential direction, the first magnet 161A, the pole piece 265A, and the second magnet 161B are arranged in this order.
[0041] In the circumferential direction, the first magnet 161A and the second magnet 161B repel each other magnetically via the pole piece 265A. That is, the magnetic pole of the first magnet 161A on the side of the pole piece 265A (the magnetic pole of surface 161Ab) is the same as the magnetic pole of the second magnet 161B on the side of the pole piece 265A (the magnetic pole of surface 161Ba). If the surface 161Ab side of the first magnet 161A is a north pole, then the surface 161Ba side of the second magnet 161B is also a north pole. If the surface 161Ab side of the first magnet 161A is a south pole, then the surface 161Ba side of the second magnet 161B is also a south pole.
[0042] In the circumferential direction, a hole H is formed between the first magnet 161A and the second magnet 161B, which is a region having higher magnetic resistance than the pole piece 265A. In the circumferential direction, the hole H is formed in the intermediate portion 265Ac of the pole piece 265A, between the first side surface 265Aa and the second side surface 265Ab. In the radial direction, the hole H is formed in the inner circumference portion 265Ad of the pole piece 265A. The hole H is located in the innermost portion (direction of arrow d) when the pole piece 265A is virtually divided into three equal parts radially. The hole H extends in the direction of the rotation axis. As shown in Figure 7, in the direction of the rotation axis, the hole H extends from one end to the other end of the pole piece 265. The hole H may contain air, or it may be filled with a material such as resin or a metal such as aluminum that has higher magnetic resistance than the pole piece 265A. In the radial direction, hole H is located outside (in the direction of arrow c) the connecting portions 166 and 167. In the radial direction, hole H is located outside (in the direction of arrow c) the inner magnet 162A included in the plurality of inner magnets 162.
[0043] In the radial direction, the dimensions of the holes H may be, for example, 1 / 2, 1 / 3, 1 / 4, 1 / 5, or 1 / 6 of the dimensions of the first magnet 161A and the second magnet 161B. In the circumferential direction, the dimensions of the holes H may be, for example, 2 / 3 or less, or 1 / 2 of the dimensions of the first magnet 161A and the second magnet 161B. The holes H may have a circular cross-section (a cross-section perpendicular to the axis of rotation), an elliptical cross-section, a polygonal cross-section such as a square, pentagon, or hexagon, or a cross-section of any other shape, as shown in the figure. Multiple holes H may be formed in the pole piece 265A. When multiple holes H are formed, the multiple holes H may be arranged, for example, in the circumferential direction, in the radial direction, or in any other direction.
[0044] The first magnet 161A is subjected to a magnetic attractive force F1a between it and the first side surface 265Aa of the pole piece 265A, and a magnetic repulsive force F2a between it and the second magnet 161B. Similarly, the second magnet 161B is subjected to a magnetic attractive force F1b between it and the second side surface 265Ab of the pole piece 265A, and a magnetic repulsive force F2b between it and the first magnet 161A. The magnitudes of the magnetic repulsive forces F2a and F2b between the first magnet 161A and the second magnet 161B are adjusted by the hole H. When the attractive forces F1a and F1b exceed the repulsive forces F2a and F2b, the first magnet 161A is attracted to the first side surface 265Aa of the pole piece 265A, and the second magnet 161B is attracted to the second side surface 265Ab of the pole piece 265A.
[0045] As shown in Figure 6, the pole piece 265A is connected to the annular portion 164 by two adjacent connecting portions 166 and 167. The two adjacent connecting portions 166 and 167 connected to the pole piece 265A extend circumferentially toward each other as they move radially outward (in the direction of arrow c), that is, as they approach the pole piece 265A. However, the two adjacent connecting portions 166 and 167 connected to the pole piece 265A may extend circumferentially toward each other as they move radially outward (in the direction of arrow c). A space S having a substantially trapezoidal cross-section (a cross-section perpendicular to the rotation axis) is formed between the two adjacent connecting portions 166 and 167 connected to the pole piece 265A. The inner magnets 162A included in the plurality of inner magnets 162 are positioned in space S between the annular portion 164 and the pole piece 265A. The portion of space S excluding the inner magnet 162A may be filled with a non-magnetic material such as resin or a metal such as aluminum.
[0046] The magnetic pole on the side of the magnetic pole piece 265A of the inner magnet 162A is the same as the magnetic pole on the side of the magnetic pole piece 265A of the first magnet 161A and the magnetic pole on the side of the magnetic pole piece 265A of the second magnet 161B. If the surface 161Ab of the first magnet 161A and the surface 161Ba of the second magnet 161B are north poles, then the magnetic pole piece 265A of the inner magnet 162A is also a north pole. If the surface 161Ab of the first magnet 161A and the surface 161Ba of the second magnet 161B are south poles, then the magnetic pole piece 265A of the inner magnet 162A is also a south pole. In this way, a magnetic force of either a north pole or a south pole is applied to each of the multiple magnetic pole pieces 265, and they are emitted radially outward as a single magnetic flux (in the direction of arrow c). The magnetic poles of the multiple magnetic pole pieces 265 are configured so that north poles and south poles alternate in the circumferential direction.
[0047] In the rotor 260 according to this embodiment, the first magnet 161A is attracted to the first side surface 265Aa of the pole piece 265A, and the second magnet 161B is attracted to the second side surface 265Ab of the pole piece 265A. Therefore, during assembly, the protrusion of the multiple outer magnets 161 is suppressed or prevented, improving workability. The attractive forces F1a and F1b can be adjusted, for example, by the position, shape, and size of the holes H. Furthermore, in the rotor 260 according to this embodiment, the region (hole H) having a higher magnetic resistance than the pole piece 265A is formed in the inner circumference 265Ad of the pole piece 265A. Therefore, workability can be improved while suppressing the influence on motor characteristics such as torque.
[0048] Although preferred embodiments of the rotor of the present invention have been described above, the rotor of the present invention is not limited to any of the above-described embodiments. For example, the number of magnetic materials (magnetic pole pieces), the number of openings, and the number of magnets of the rotor of the present invention may be any number as long as it functions as a rotor. The rotor of the present invention does not have to have an internal magnet. The rotor of the present invention may have both the air gap shown in the first embodiment and the hole shown in the second embodiment. The rotor of the present invention may also be the rotor of an outer rotor type motor that surrounds the stator.
[0049] Furthermore, those skilled in the art can modify the rotor of the present invention as appropriate, and change the shape, dimensions, and combinations of various components, in accordance with conventionally known knowledge. As long as such modifications still possess the configuration of the present invention, they are of course included within the scope of the present invention. [Explanation of Symbols]
[0050] 100, 200...motor, 160, 260...rotor, 161...multiple magnets (multiple outer magnets), 161A...first magnet, 161B...second magnet, 162A...inner magnet, 164...annular section, 165A, 265A...magnetic material (magnetic pole pieces), 165Aa, 265Aa...first side surface, 165Ab, 265Ab...second side surface, 165Ac, 265Ac...intermediate section, 165Ad, 265Ad...inner circumference, 165Ae, 165Af...recess, 168, 268...multiple openings, Ga, Gb...region (void), H...region (hole).
Claims
1. Multiple openings extending in the direction of the rotation axis, Multiple magnets arranged in the multiple openings, The device comprises a magnetic material positioned between the plurality of magnets in the circumferential direction, In the circumferential direction, the magnetic material comprises a first surface, a second surface, and an intermediate portion between the first surface and the second surface. The plurality of magnets include a first magnet located on the first side surface of the magnetic material and a second magnet located on the second side surface of the magnetic material. In the circumferential direction, the first magnet and the second magnet repel each other magnetically through the magnetic material. In the circumferential direction, a region having higher magnetic resistance than the magnetic material is formed between the first magnet and the second magnet. The aforementioned region extends in the direction of the rotation axis, The first magnet is magnetically attracted to the first side surface of the magnetic material. The rotor is magnetically attracted to the second side surface of the magnetic material by the second magnet.
2. The rotor according to claim 1, wherein the magnitude of the magnetic repulsive force between the first magnet and the second magnet is adjusted by the region.
3. The rotor according to claim 1 or 2, wherein, in the circumferential direction, the region is formed between the first magnet or the second magnet and the magnetic material, or in the intermediate portion.
4. The rotor according to claim 3, wherein, in the circumferential direction, the region is formed between the inner circumference of the magnetic material and the first magnet.
5. The rotor according to claim 3 or 4, wherein, in the circumferential direction, the region is formed between the inner circumference of the magnetic material and the second magnet.
6. The rotor according to any one of claims 1 to 5, wherein the region is formed by a recess or a hole.
7. The rotor according to any one of claims 1 to 6, comprising an annular portion connected to the magnetic material.
8. The aforementioned multiple magnets are used as multiple outer magnets, The rotor according to claim 7, further comprising an inner magnet disposed radially between the annular portion and the magnetic material.
9. The rotor according to claim 8, wherein the magnetic pole on the magnetic material side of the inner magnet is the same as the magnetic pole on the magnetic material side of the first magnet and the magnetic pole on the magnetic material side of the second magnet.