Method for manufacturing rotor, rotor, and electric motor

Abstract

This method for manufacturing a rotor (10) includes: a step of arranging a rotor core (12) and a plurality of magnets (13) arranged along the outer peripheral surface of the rotor core (12) in a mold (100); a step of inserting a position regulation pin (110) into each gap (G) between two adjacent magnets (13) in the plurality of magnets (13); a step of fixing the plurality of magnets (13) to the rotor core (12) by injecting a resin material (14L) in a fluid state into the mold (100) and curing the resin material (14L); and a step of discharging the position regulation pin (110) from the gap (G).

Description

Rotor Manufacturing Method, Rotor and Electric Motor

[0001] The present disclosure relates to a rotor manufacturing method, a rotor and an electric motor.

[0002] Electric motors are used in various devices such as household electrical appliances and industrial electrical equipment. For example, as an electric motor used in an air conditioner, a fan motor having a rotating fan attached to a rotating shaft is known.

[0003] An electric motor includes a rotor having a rotating shaft and a stator that generates magnetic force to rotate the rotor. As an electric motor, a surface permanent magnet (SPM) motor is known. An SPM rotor in which a plurality of permanent magnets are arranged on the outer circumferential surface of a rotor core is used in an SPM motor (Patent Document 1).

[0004] Japanese Patent No. 3309844

[0005] In an SPM rotor, the magnets are fixed to the rotor core so that the magnets do not scatter due to centrifugal force. The rotor core is formed in a substantially cylindrical shape. For example, a technique for fixing magnets to a rotor core with resin has been proposed. In this case, a plurality of magnets arranged along the outer circumferential surface of the rotor core and the rotor core are placed in a mold, a fluid resin material is injected into the mold and cured, whereby the plurality of magnets can be fixed to the rotor core.

[0006] However, when a rotor is manufactured in this manner, the positions of the magnets may deviate in the circumferential direction. That is, the magnets may deviate from predetermined angular positions. Torque performance decreases in an electric motor incorporating a rotor with magnets deviated in the circumferential direction.

[0007] Therefore, in order to prevent the circumferential position (angular position) of the magnets from deviating, a protrusion is provided on the outer circumferential surface of the rotor core, the protrusion is inserted into the gap between two adjacent magnets, and the magnets and the rotor core are placed in a mold to restrict the positions of the magnets. In this state, it is conceivable to inject a liquid resin material into the mold and cure the resin material.

[0008] However, if such protrusions are provided on the outer surface of the rotor core, the dimensions of the base material of the electromagnetic steel sheet constituting the rotor core will increase by the height of the protrusions, thus increasing the cost of the rotor core.

[0009] On the other hand, if the height of the protrusions is reduced to suppress the cost increase of the rotor core caused by the protrusions, the magnets will ride up on the protrusions during rotor manufacturing, ultimately causing the magnets to shift in the circumferential direction.

[0010] Therefore, a certain height of the protrusion is necessary, but in order to prevent the magnet from riding up onto the protrusion, the height of the protrusion must be at least half the length of the magnet's side surface. However, since the protrusion is part of the rotor core, which is a magnetic material, increasing the height of the protrusion causes the magnetic flux of two adjacent magnets to short-circuit through the protrusion, reducing the amount of magnetic flux the magnet provides to the stator. In other words, the amount of magnetic flux required for the rotor decreases. As a result, the torque performance of the electric motor decreases.

[0011] Thus, in SPM rotors manufactured using conventional methods, the position of the magnets shifts in the circumferential direction, and the amount of magnetic flux in the rotor decreases due to protrusions on the outer surface of the rotor core, resulting in a decrease in the performance of the electric motor.

[0012] This disclosure was made to solve these problems and aims to provide a method for manufacturing a rotor, a rotor, and an electric motor that can realize a high-performance electric motor.

[0013] To achieve the above objective, one embodiment of a rotor manufacturing method according to the present disclosure includes the steps of: placing a rotor core and a plurality of magnets arranged along the outer circumferential surface of the rotor core in a mold; inserting a position regulating pin into the gap between each of two adjacent magnets among the plurality of magnets; injecting a fluid resin material into the mold and curing the resin material to fix the plurality of magnets to the rotor core; and discharging the position regulating pin from the gap.

[0014] Furthermore, one embodiment of the rotor according to the present disclosure comprises a rotor core, a plurality of magnets arranged on the outer circumferential surface of the rotor core and aligned in the circumferential direction of the rotor core, and a resin for fixing the plurality of magnets to the rotor core, wherein a gap exists between each of two adjacent magnets among the plurality of magnets, and the resin has an embedded portion which is a part embedded in the gap, and a recessed hole is formed in the embedded portion.

[0015] Furthermore, one embodiment of the electric motor according to this disclosure comprises the rotor described above and a stator that generates a magnetic force acting on the rotor.

[0016] According to this disclosure, a rotor and motor capable of realizing a high-performance electric motor can be obtained.

[0017] Figure 1 is a perspective view of an electric motor according to an embodiment. Figure 2 is a cross-sectional view of an electric motor according to an embodiment when cut along a plane containing the axis of the rotating shaft. Figure 3 is a cross-sectional view of an electric motor according to an embodiment when cut along the line III-III in Figure 2. Figure 4 is a perspective view of a rotor according to an embodiment viewed from one side. Figure 5 is a perspective view of a rotor according to an embodiment viewed from the other side. Figure 6 is an exploded perspective view of a rotor according to an embodiment. Figure 7 is a cross-sectional view of a rotor according to an embodiment when cut along a plane containing the axis of the rotating shaft and including the magnet. Figure 8 is a cross-sectional view of a rotor according to an embodiment when cut along a plane containing the axis of the rotating shaft and passing through a hole formed in the resin. Figure 9 is a cross-sectional view of a rotor according to an embodiment when cut along a plane perpendicular to the axis of the rotating shaft and passing through a hole formed in the resin. Figure 10 is a cross-sectional view of a rotor according to an embodiment when cut along a plane perpendicular to the axis of the rotating shaft and not passing through a hole in the resin. Figure 11 is an exploded perspective view of a rotor according to another embodiment. Figure 12A is a diagram showing the rotor core and magnet arrangement process in the manufacturing method of a rotor according to an embodiment. Figure 12B is a diagram showing the pin insertion process in the rotor manufacturing method according to the embodiment. Figure 12C is a diagram showing the magnet fixing process in the rotor manufacturing method according to the embodiment. Figure 12D is a diagram showing the pin ejection process in the rotor manufacturing method according to the embodiment. Figure 13 is a cross-sectional view of a comparative example rotor. Figure 14A is a diagram showing the rotor core and magnet arrangement process in the rotor manufacturing method of the comparative example rotor. Figure 14B is a diagram showing the magnet fixing process in the rotor manufacturing method of the comparative example rotor. Figure 15 is a cross-sectional view of a modified rotor when cut in a plane perpendicular to the axis of rotation and not passing through the holes in the resin.

[0018] The embodiments of this disclosure will be described below with reference to the drawings. The embodiments described below are all specific examples of this disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions of components, and connection configurations shown in the following embodiments are examples and are not intended to limit this disclosure. Accordingly, any components in the following embodiments that are not described in the independent claims representing the highest-level concepts of this disclosure will be described as optional components.

[0019] Please note that each figure is a schematic diagram and not necessarily a strictly accurate representation. Therefore, the scale and other aspects may not necessarily be consistent across all figures. In addition, the same reference numerals are used for substantially identical components in each figure, and redundant explanations are omitted or simplified.

[0020] Furthermore, in this specification, the terms "up" and "down" do not necessarily refer to the absolute upward (vertically upward) and downward (vertically downward) directions in spatial perception. In this embodiment, for convenience, the direction in which the axis C of the rotating shaft 11 extends is defined as the up and down direction, but this up and down direction may differ from the actual up and down direction depending on the operating conditions of the electric motor 1. Also, in this embodiment, the radial direction of the rotor 10 and stator 20 is defined as the "radial direction," and the rotational direction of the rotor 10 is defined as the "circumferential direction." In other words, the direction perpendicular to the axis C of the rotating shaft 11 is the "radial direction," and the direction that circles the axis C of the rotating shaft 11 is the "circumferential direction." Note that the direction in which the axis C of the rotating shaft 11 extends (the longitudinal direction of the rotating shaft 11) is the "axial direction."

[0021] (Embodiment) First, the configuration of the electric motor 1 according to the embodiment will be described using Figures 1 to 3. Figure 1 is a perspective view of the electric motor 1 according to the embodiment. Figures 2 and 3 are cross-sectional views of the electric motor 1 according to the embodiment. Figure 2 shows a cross-section when cut along a plane containing the axis C of the rotating shaft 11, and Figure 3 shows a cross-section when cut along the line III-III in Figure 2. Note that only the parts that appear in the cross-section are shown in Figures 2 and 3.

[0022] As shown in Figures 1 to 3, the electric motor 1 comprises a rotor 10 having a rotating shaft 11, a stator 20, a sleeve bearing 30 supporting the rotating shaft 11, a holder 40 housing the sleeve bearing 30, a first housing ring 51, and a second housing ring 52.

[0023] In this embodiment, the electric motor 1 is a brushless motor that does not use brushes. Furthermore, the electric motor 1 is a molded motor in which the stator 20 is covered with molded resin 60.

[0024] As shown in Figures 2 and 3, the electric motor 1 is an inner-rotor type motor in which the rotor 10 is positioned inside the stator 20. In other words, the stator 20 is positioned to surround the rotor 10. The rotor 10 and the stator 20 are positioned with a gap between them.

[0025] The rotor 10 generates a magnetic force that acts on the stator 20. In this embodiment, the direction of the main magnetic flux generated by the rotor 10 is perpendicular to the direction in which the axis C of the rotation shaft 11 extends (radial direction). The rotor 10 has a configuration in which multiple N poles and S poles are repeated along the circumferential direction, and rotates due to the magnetic force generated by the stator 20. The rotor 10 rotates with the axis C of the rotation shaft 11 as its center of rotation.

[0026] The rotor 10 is positioned with respect to the stator 20 via an air gap. Specifically, a small air gap exists between the surface of the rotor 10 and the surface of the stator 20. As will be described in detail later, the rotor 10 has a rotating shaft 11, a rotor core 12 through which the rotating shaft 11 is inserted, and a plurality of magnets 13 held in the rotor core 12. In this embodiment, the rotor 10 is an SPM rotor in which the magnets 13 are arranged on the outer surface of the rotor core 12. Therefore, the electric motor 1 in this embodiment is an SPM motor.

[0027] The rotating shaft 11 is a shaft containing the axis C, and is a long, rod-shaped member. For example, the rotating shaft 11 is a metal rod made of a metal material such as SUS. The axis C of the rotating shaft 11 is the center of rotation when the rotor 10 rotates. The longitudinal direction of the rotating shaft 11 is the direction in which the rotating shaft 11 extends (extension direction), and is the direction of the axis C.

[0028] The rotating shaft 11 includes a first end 11a, which is one end in the direction in which the rotating shaft 11 extends, and a second end 11b, which is the other end in the direction in which the rotating shaft 11 extends. The second end 11b is the end opposite to the first end 11a. Both ends of the rotating shaft 11, the first end 11a and the second end 11b, protrude outward. Specifically, the first end 11a of the rotating shaft 11 protrudes outward from the through hole of the first housing ring 51. Also, the second end 11b of the rotating shaft 11 protrudes outward from the through hole of the second housing ring 52. The portions of the rotating shaft 11 that protrude from the first housing ring 51 and the second housing ring 52 can be used as the output shaft of the rotating shaft 11.

[0029] The stator 20 generates a magnetic force that acts on the rotor 10. The stator 20 is configured such that multiple north poles and south poles alternate along the circumferential direction to generate a magnetic flux on the air gap surface with the rotor 10. In this embodiment, the stator 20 is composed of an electromagnet and has a stator core 21 (iron core) and windings 22 attached to the stator core 21. Note that the windings 22 are shown schematically in Figures 2 and 3.

[0030] The stator core 21 generates a magnetic force to rotate the rotor 10. The stator core 21 is a magnetic body made of a magnetic material. For example, the stator core 21 is a laminate in which a plurality of electromagnetic steel sheets formed into a predetermined shape are stacked in the direction in which the axis C of the rotating shaft 11 extends (axial direction). Note that the stator core 21 is not limited to a laminate of electromagnetic steel sheets, but may be a bulk body made of a magnetic material. As shown in Figures 2 and 3, a small air gap exists between the inner circumferential surface of the stator core 21 and the magnet 13 of the rotor 10.

[0031] As shown in Figure 3, the stator core 21 has a plurality of teeth 21a that generate the main magnetic flux. Each of the plurality of teeth 21a is a magnetic pole tooth and generates a magnetic force when energized by the winding 22. The plurality of teeth 21a are formed to protrude inward in the radial direction, which is perpendicular to the axis C of the rotation axis 11. In other words, the plurality of teeth 21a protrude toward the rotation axis 11. The plurality of teeth 21a are arranged at equal intervals along the circumferential direction, forming a slot between two adjacent teeth 21a. In this embodiment, the stator core 21 is provided with 12 teeth 21a. In other words, the number of slots in the stator 20 is 12.

[0032] The winding 22 is a winding coil wound around the teeth 21a of the stator core 21 via an insulator 23. The winding 22 is wound around the stator core 21 in such a way that it generates a magnetic force that acts on the magnet 13 of the rotor 10 when current flows through it. The winding 22 is, for example, a concentrated winding wound around each tooth 21a via an insulator 23 and is housed in a slot of the stator core 21. The wire constituting the winding 22 is, for example, an insulated coated wire, and has a conductive wire made of a conductive material such as copper or aluminum as the core wire, and an insulating film that covers this conductive wire. The insulator 23 is made of an insulating resin material or the like and is placed between the winding 22 and the stator core 21.

[0033] When the windings 22 are energized, a magnetic field is generated from each of the multiple teeth 21a. For example, the multiple windings 22 are electrically connected as a three-phase winding so that the rotor 10 rotates as a three-phase synchronous motor. In other words, the motor 1 in this embodiment is a surface-mounted permanent magnet synchronous motor (SPMSM). In this case, the multiple windings 22 are composed of unit coils for the U-phase, V-phase, and W-phase, each of which is electrically 120 degrees out of phase with respect to the others. That is, the windings 22 attached to each tooth 21a are energized and driven by three-phase alternating current, which is energized for each of the U-phase, V-phase, and W-phase. As a result, a main magnetic flux is generated in each tooth 21a.

[0034] In the electric motor 1 configured in this way, when current is supplied to the windings 22 of the stator 20, a field current flows through the windings 22, generating a magnetic field. This generates a magnetic flux directed from the stator 20 toward the rotor 10. Specifically, a magnetic flux is generated from each of the multiple teeth 21a of the stator core 21 in the stator 20 toward the rotor 10. Meanwhile, in the rotor 10, a magnetic flux is generated passing through the stator 20 by the magnets 13 placed on the outer surface of the rotor core 12. The magnetic force generated by the interaction between the magnetic flux generated from the magnets 13 of the rotor 10 and the magnetic flux generated in the stator 20 becomes a torque that rotates the rotor 10, causing the rotor 10 to rotate.

[0035] As shown in Figures 1 to 3, the stator 20 is covered with molded resin 60. The molded resin 60 covers the outer portion of the stator 20 around its entire circumference. Specifically, the molded resin 60 covers the outer portions of the stator core 21 and the windings 22.

[0036] As shown in Figure 2, the molded resin 60 covering the stator 20 constitutes a housing that encloses the rotor 10. The molded resin 60 is formed into a cylindrical shape with openings at both ends in the direction in which the rotating shaft 11 extends. One opening of the molded resin 60 is covered by a first housing ring 51, and the other opening of the molded resin 60 is covered by a second housing ring 52.

[0037] The molding resin 60 is made of an insulating resin material with excellent thermal conductivity, such as polyester resin or epoxy resin. The molding resin 60 is also made of a thermosetting resin. In this embodiment, the molding resin 60 is made of an unsaturated polyester, which is a thermosetting resin. Specifically, the molding resin 60 is made of a white BMC unsaturated polyester resin.

[0038] Although not shown in the figures, a circuit board to which the windings 22 of the stator 20 are connected may be embedded in the molded resin 60. In this case, the ends of the windings 22 of each phase are connected at the winding connection section of the circuit board. For example, the circuit board has pattern wiring formed therein for electrically connecting multiple windings 22 for each of the U, V, and W phases, and the ends of the windings 22 of each phase are electrically connected to the pattern wiring of the circuit board by solder or the like.

[0039] The sleeve bearing 30 is a bearing that rotatably supports the rotating shaft 11. The sleeve bearing 30 is a sliding bearing. Specifically, the sleeve bearing 30 is a cylindrical, metal sleeve bearing. In this embodiment, the sleeve bearing 30 is an oil-impregnated metal bearing, and is made of sintered metal impregnated with lubricating oil.

[0040] As shown in Figure 2, the rotating shaft 11 passes through the sleeve bearing 30. The rotating shaft 11 is inserted through a through hole formed in the sleeve bearing 30. The rotating shaft 11 and the inner surface of the through hole in the sleeve bearing 30 are in contact. In this embodiment, the sleeve bearing 30 contacts the rotating shaft 11 at two points: the inner surface of the upper end and the inner surface of the lower end of the sleeve bearing 30. The rotating shaft 11 is supported by only one sleeve bearing 30. Therefore, one sleeve bearing 30 supports the rotating shaft 11 at two points. The sleeve bearing 30 is slidable along the rotating shaft 11.

[0041] A first slinger 71 and a second slinger 72 are provided to prevent lubricating oil that has leaked out of the sleeve bearing 30 from leaking to the outside. The sleeve bearing 30 is sandwiched between the first slinger 71 and the second slinger 72. The first slinger 71 and the second slinger 72 are fixed to the rotating shaft 11. Therefore, the first slinger 71 and the second slinger 72 rotate together with the rotating shaft 11. In this embodiment, the first slinger 71 and the second slinger 72 are fixed to the rotating shaft 11 by being press-fitted onto the rotating shaft 11.

[0042] The first slinger 71 is in contact with the rotor core 12 of the rotor 10, but is not limited to this. The second slinger 72 is housed in the holder 40. The first slinger 71 and the second slinger 72 are made of a resin material such as polyamide resin. One or more washers may be placed between the first slinger 71 and the sleeve bearing 30. Also, one or more washers may be placed between the second slinger 72 and the sleeve bearing 30.

[0043] The holder 40 holds the sleeve bearing 30. The holder 40 may be made of a metal material or a resin material. In this embodiment, the holder 40 is a metal holder made of metal. The holder 40 is fixed to the molded resin 60. The holder 40 is a bottomed cylindrical shape.

[0044] As shown in Fig. 2, the first housing ring 51 and the second housing ring 52 are fixed to a mold resin 60. The first housing ring 51 is provided so as to close one opening of the mold resin 60, and the second housing ring 52 is provided so as to close the other opening of the mold resin 60.

[0045] The rotating shaft 11 passes through the first housing ring 51 and the second housing ring 52. Specifically, the first housing ring 51 is formed with a through-hole 51a through which the rotating shaft 11 passes, and the second housing ring 52 is formed with a through-hole 52a through which the rotating shaft 11 passes. The rotating shaft 11 is not in contact with the through-hole 51a and the through-hole 52a.

[0046] The first housing ring 51, the second housing ring 52, and the mold resin 60 constitute outer shell components that form the outer shell of the electric motor 1.

[0047] The first housing ring 51 and the second housing ring 52 are made of a metal material such as iron. For example, the first housing ring 51 and the second housing ring 52 are formed into a predetermined shape by subjecting a metal plate having a constant thickness to press working or the like. Although the first housing ring 51 and the second housing ring 52 are made of the same metal material, the present invention is not limited thereto.

[0048] Note that, in the electric motor 1 according to the present embodiment, a vibration-proof ring 80 is attached to each of the first housing ring 51 and the second housing ring 52. In other words, the electric motor 1 includes two vibration-proof rings 80. One of the two vibration-proof rings 80 is fitted into the cylindrical portion of the protruding part of the first housing ring 51, and the other of the two vibration-proof rings 80 is fitted into the cylindrical portion of the protruding part of the second housing ring 52. The vibration-proof ring 80 is a vibration-proof member that suppresses transmission of vibration generated in the electric motor 1 to the outside of the electric motor 1 during operation of the electric motor 1.

[0049] The electric motor 1 configured in this way can be used, for example, as a fan motor mounted on the indoor unit of an air conditioner. In this case, the electric motor 1 is mounted on a support base via a vibration-damping ring 80. When the electric motor 1 is used as a fan motor, a rotating fan (load fan) is attached to the rotating shaft 11 of the electric motor 1 as a load.

[0050] Here, the detailed configuration of the rotor 10 will be described using Figures 4 to 10, with reference to Figures 2 and 3. Figures 4 and 5 are perspective views of the rotor 10 according to the embodiment. Figure 6 is an exploded perspective view of the rotor 10 according to the embodiment. Figures 7 to 10 are cross-sectional views of the rotor 10 according to the embodiment. Figure 7 is a cross-sectional view of the rotor 10 when cut by a plane that includes the axis C of the rotating shaft 11 and also includes the magnet 13, and Figure 8 is a cross-sectional view of the rotor 10 when cut by a plane that includes the axis C of the rotating shaft 11 and also passes through the hole 15 formed in the resin 14. Figure 9 is a cross-sectional view of the rotor 10 when cut by a plane perpendicular to the axis C of the rotating shaft 11 and also passes through the hole 15 formed in the resin 14, and Figure 10 is a cross-sectional view of the rotor 10 when cut by a plane perpendicular to the axis C of the rotating shaft 11 and also does not pass through the hole 15 formed in the resin 14. Specifically, Figure 9 shows a cross-section along the IX-IX line in Figure 8, and Figure 10 shows a cross-section along the X-X line in Figure 8. Note that the rotation axis 11 is omitted in Figures 4 to 10.

[0051] As described above, the rotor 10 includes a rotating shaft 11, a rotor core 12 inserted through the rotating shaft 11, and a plurality of magnets 13 held in the rotor core 12. The rotor 10 further includes a resin 14 that fixes the plurality of magnets 13 to the rotor core 12.

[0052] The rotor core 12 shown in Figures 4 to 10 is the iron core that forms the core of the rotor 10. In this embodiment, the rotor core 12 is a laminate in which a plurality of steel plates are stacked in the direction in which the rotation axis 11 extends (axis C direction). Each of the plurality of steel plates is a magnetic material, for example, a punched electrical steel plate formed into a predetermined shape. The plurality of steel plates are fixed to each other by crimping or welding. Note that the rotor core 12 is not limited to a laminate of a plurality of steel plates, but may also be a bulk body made of magnetic material.

[0053] As shown in Figures 2 and 3, the rotating shaft 11, which is inserted through the rotor core 12, is fixed to the rotor core 12. Specifically, an insertion hole 12a is formed in the center of the rotor core 12, and the rotating shaft 11 is fixed to the rotor core 12 by press-fitting or shrink-fitting into this insertion hole 12a.

[0054] As shown in Figures 5 and 7, in this embodiment, the rotor core 12 has a shape with a recess. Specifically, the rotor core 12 is composed of two annular members with different inner diameters of through holes formed in the center. Therefore, the multiple steel plates constituting the rotor core 12 are composed of two types of steel plates with different punching patterns. The insertion hole 12a of the rotor core 12 is a through hole in the annular member with a smaller inner diameter.

[0055] The rotor core 12 has a yoke (rotor yoke). Specifically, at least the annular outer circumference of the rotor core 12 is the yoke. In other words, the part of the rotor core 12 facing the magnet 13 is the yoke. The yoke of the rotor core 12 is a back yoke located behind the magnet 13. The outer circumferences of the two annular members of the rotor core 12 with different inner diameters of through holes both face the magnet 13 and both are yokes. The entire rotor core 12 may also be a yoke.

[0056] As shown in Figure 6, the rotor core 12 has projections 12b. The projections 12b are provided on the outer circumferential surface of the rotor core 12. Specifically, the rotor core 12 is provided with multiple projections 12b. Each projection 12b protrudes radially outward from the outer circumferential surface of the rotor core 12.

[0057] As shown in Figures 9 and 10, each of the multiple protrusions 12b is located in the gap G between two adjacent magnets 13. In other words, each protrusion 12b is sandwiched between two adjacent magnets 13. Specifically, the protrusions 12b are provided for all magnets 13 so as to be located in the gap G between two adjacent magnets 13. In this embodiment, the rotor 10 has eight magnets 13, so the rotor core 12 is provided with eight protrusions 12b.

[0058] The height of the projection 12b is less than half the thickness of the side surface of the magnet 13 in the radial direction of the rotor core 12. Specifically, the height of the projection 12b is 1 / 3 or less of the thickness of the side surface of the magnet 13, and more specifically, 1 / 4 or less of the thickness of the side surface of the magnet 13. In this embodiment, the height of the projection 12b is 1 / 8 of the thickness of the side surface of the magnet 13.

[0059] Furthermore, as shown in Figure 11, the height of the projection 12b may be zero. In other words, the rotor core 12A does not need to have a projection 12b.

[0060] In this embodiment, the multiple protrusions 12b are of the same height. Specifically, all the protrusions 12b are of the same height. Also, as shown in Figure 6, each of the multiple protrusions 12b extends along the axis C direction of the rotation shaft 11. Specifically, each protrusion 12b is provided from one end to the other end of the rotor core 12 in the axis C direction of the rotation shaft 11. Note that the heights of the multiple protrusions 12b do not have to be the same. In other words, multiple protrusions 12b of different heights may be provided on the rotor core 12.

[0061] The outer circumferential surface of the rotor core 12 includes a cylindrical surface. Therefore, when viewed from the direction of the axis C of the rotation shaft 11, the outer shape of the rotor core 12 includes a circular arc. Specifically, the outer circumferential surface of the rotor core 12 is cylindrical as a whole, except for the projection 12b. Therefore, when viewed from the direction of the axis C of the rotation shaft 11, the outer shape of the rotor core 12 is circular, except for the projection 12b.

[0062] As shown in Figures 9 and 10, multiple magnets 13 are arranged on the outer circumferential surface of the rotor core 12. The multiple magnets 13 are in contact with the outer circumferential surface of the rotor core 12. Furthermore, the multiple magnets 13 are arranged in the circumferential direction of the rotor core 12. In other words, the multiple magnets 13 are arranged in an annular shape. Each of the multiple magnets 13 is positioned at a predetermined position (angle position) in the circumferential direction. In this embodiment, all of the multiple magnets 13 have the same shape and are arranged at equal intervals along the circumferential direction. Specifically, eight magnets 13 are arranged in an annular shape at equal intervals so that the rotor 10 has eight poles. In other words, the eight magnets 13 are arranged at 45-degree intervals.

[0063] The multiple magnets 13 are arranged so that two adjacent magnets 13 are close together. In this embodiment, there is a gap G between each of the two adjacent magnets 13 in the multiple magnets 13. That is, there are multiple gaps G along the circumferential direction of the rotor 10. A projection 12b provided on the rotor core 12 is inserted into the gap G between two adjacent magnets 13. In other words, two adjacent magnets 13 are aligned via the projection 12b.

[0064] Since the rotor 10 is an SPM rotor, as shown in Figure 3, each of the multiple magnets 13 directly faces the stator core 21 of the stator 20 via an air gap. For this reason, the outer surfaces of the multiple magnets 13 are exposed surfaces and are the outer surfaces of the rotor 10. Thus, the surfaces of the magnets 13 facing the stator 20 (radially outer surfaces) are the air gap surfaces of the rotor 10 relative to the stator 20. Specifically, an air gap exists between the radially outer surfaces (exposed surfaces) of the multiple magnets 13 and the radially inner surfaces of the teeth 21a of the stator core 21.

[0065] The multiple magnets 13 are magnetized permanent magnets. The magnetization direction of each magnet 13 is in the radial direction of the rotor core 12. The multiple magnets 13 are arranged such that north poles and south poles alternate multiple times along the circumferential direction. Therefore, the magnetization directions of two adjacent magnets 13 are opposite, with the south pole and north pole facing in opposite directions. In other words, for two adjacent magnets 13, the magnetic pole surface that becomes the south pole of one magnet 13 is the outer surface (exposed surface) of the magnet 13, and the magnetic pole surface that becomes the south pole of the other magnet 13 is the inner surface (the surface on the outer circumferential side of the rotor core 12).

[0066] Magnet 13 is a sintered magnet. For example, magnet 13 is a ferrite magnet made of a sintered ferrite magnet. However, magnet 13 is not limited to a ferrite magnet. For example, magnet 13 may be a rare earth magnet. In this case, a neodymium rare earth magnet mainly composed of neodymium-iron-boron (Nd-Fe-B) can be used as magnet 13.

[0067] In this embodiment, as shown in Figure 3, the outer circumferential surface of the rotor core 12 is cylindrical, so the magnets 13 arranged on the outer circumferential surface of the rotor core 12 are arc-shaped. Specifically, the inner and outer circumferential surfaces of the magnets 13 are cylindrical. In other words, the cross-sectional shape of the magnets 13 when cut by a plane perpendicular to the axis C direction of the rotation axis 11 is arc-shaped. In this embodiment, each of the multiple magnets 13 is a fan-shaped segment type magnet. Also, as shown in Figure 7, each magnet 13 extends along the axis C direction of the rotation axis 11. Specifically, each magnet 13 extends from one end to the other end of the rotor core 12 in the axis C direction of the rotation axis 11.

[0068] Regarding the timing of magnetization of the magnet 13, it is possible to magnetize the magnet 13 after fixing it to the rotor core 12, or to magnetize it in advance before fixing it to the rotor core 12. However, considering the ease of positioning the magnet 13 in the mold when fixing it to the rotor core 12, it is preferable to magnetize the magnet 13 after fixing it to the rotor core 12.

[0069] As shown in Figures 9 and 10, the multiple magnets 13 are fixed to the rotor core 12 by resin 14. The multiple magnets 13 are fixed to the rotor core 12 by an injection molding machine. In other words, the resin 14 is a resin molded body formed by solidifying resin material injected into the mold of an injection molding machine in which the rotor core 12 and the multiple magnets 13 are set.

[0070] The resin 14 is made of an insulating resin material with excellent thermal conductivity, such as polyester resin or epoxy resin. Alternatively, the resin 14 may be made of a thermosetting resin. For example, the resin 14 may be made of an unsaturated polyester, which is a thermosetting resin. Specifically, the resin 14 may be made of a white BMC unsaturated polyester resin. Note that the resin 14 may be made of polybutylene terephthalate (PBT) or the like, instead of polyester resin or epoxy resin.

[0071] As shown in Figures 9 and 10, the magnet 13 is fixed to the rotor core 12 by covering a portion of the magnet 13 with resin 14. In other words, a portion of the resin 14 covers a portion of the outer circumferential surface of the magnet 13. Therefore, the resin 14 has a covering portion 14a that covers a portion of the outer circumferential surface of the magnet 13.

[0072] Furthermore, the resin 14 has embedded portions 14b, which are parts embedded in the gap G between two adjacent magnets 13. The embedded portions 14b are present in all the gaps G between two adjacent magnets 13. In other words, the resin 14 has multiple embedded portions 14b.

[0073] A recessed hole 15 is formed in the embedded portion 14b of the resin 14. As shown in Figures 4 to 6 and Figure 8, the hole 15 is a concave recess formed in a part of the outer surface of the resin 14. The hole 15 has a side surface and a bottom surface. For example, the hole 15 is a rectangular parallelepiped, and the opening shape of the hole 15 is rectangular. However, the hole 15 is not limited to a rectangular parallelepiped, and may be a cylinder, an elliptical cylinder, or a column with an oval cross-section. In this case, the opening shape of the hole 15 is circular, elliptical, or has an oval cross-section. In addition, the opening shape of the hole 15 may be any other shape as long as the objective of this disclosure is achieved.

[0074] As shown in Figure 9, the holes 15 are formed in each of the multiple embedded portions 14b. Specifically, holes 15 are formed in all of the embedded portions 14b. Each hole 15 reaches the respective side surface of two adjacent magnets 13. Therefore, the respective side surfaces of two adjacent magnets 13 are exposed.

[0075] As shown in Figures 4 to 6, multiple holes 15 are formed in each of the multiple embedded portions 14b along the axial direction of the rotor core 12 (i.e., in the direction of the axis C of the rotation axis 11). Specifically, two holes 15 are formed in each embedded portion 14b. In other words, two holes 15 are formed in each of the gaps G between two adjacent magnets 13. One of the two holes 15 is formed at one end of the rotor core 12 in the direction of the axis C of the rotation axis 11, and the other of the two holes 15 is formed at the other end of the rotor core 12 in the direction of the axis C of the rotation axis 11.

[0076] Next, the manufacturing method of the rotor 10 configured in this way will be explained using Figures 12A to 12D. Figures 12A to 12D are diagrams illustrating the manufacturing method of the rotor 10 according to the embodiment. Figure 12A shows the rotor core and magnet arrangement process, Figure 12B shows the pin insertion process, Figure 12C shows the magnet fixing process, and Figure 12D shows the pin ejection process.

[0077] When manufacturing the rotor 10, first, as shown in Figure 12A, the rotor core 12 and a plurality of magnets 13 arranged along the outer circumferential surface of the rotor core 12 are placed in the mold 100 of the injection molding machine (first step: rotor core and magnet placement step).

[0078] Specifically, the rotor core 12 is placed in the mold 100, and a plurality of magnets 13 are placed between the rotor core 12 and the mold 100. As a result, the plurality of magnets 13 are sandwiched between the rotor core 12 and the inner surface of the mold 100, thereby restricting the position of each magnet 13 in the radial direction of the rotor core 12. At this time, it is preferable that the plurality of magnets 13 are in contact with the outer surface of the rotor core 12. In this case, it is preferable to move the radially movable push pin radially inward and press the push pin against the outer surface of the magnet 13. This makes it possible to press the magnet 13 against the rotor core 12, and thus maintain the state in which the magnet 13 is in contact with the rotor core 12.

[0079] Furthermore, when arranging multiple magnets 13 along the outer circumferential surface of the rotor core 12, the multiple magnets 13 are positioned such that the protrusions 12b provided on the outer circumferential surface of the rotor core 12 are inserted into the gaps G between two adjacent magnets 13. This prevents the multiple magnets 13 from moving in the circumferential direction due to the protrusions 12b of the rotor core 12, thus enabling the circumferential positioning of the multiple magnets 13. Therefore, the multiple magnets 13 can be positioned at predetermined positions (angular positions) in the circumferential direction of the rotor core 12.

[0080] The mold 100 is composed of, for example, multiple blocks. For instance, an injection molding machine is vertical. In this case, the mold 100 is configured to open and close in the vertical direction (in the direction of the axis C of the rotation axis 11).

[0081] Next, as shown in Figure 12B, a position regulating pin 110 is inserted into the gap G between each of two adjacent magnets 13 among the multiple magnets 13 (second step: pin insertion step).

[0082] The position regulating pins 110 are pin back pins and can be moved radially around the rotor core 12. In other words, the position regulating pins 110 can be moved radially outward or radially inward around the rotor core 12. The position regulating pins 110 are provided in the mold 100 together with a sliding mechanism (not shown) that slides the position regulating pins 110. The number of position regulating pins 110 corresponds to the number of gaps G between two adjacent magnets 13. In this embodiment, eight position regulating pins 110 are arranged at equal intervals to surround the rotor core 12. The position regulating pins 110 are housed in a position regulating pin housing 120 provided in the mold 100.

[0083] In this process, as shown by the arrows in Figure 12B, all the position regulating pins 110 are moved simultaneously radially inward from the rotor core 12, and all the position regulating pins 110 are slid so that they protrude from the outside of the rotor core 12 into the inside of the mold 100. This allows each position regulating pin 110 to be inserted into the gap G between each of two adjacent magnets 13 among the multiple magnets 13.

[0084] In this case, the position regulating pin 110 is inserted into the gap G such that the tip of the position regulating pin 110 faces the tip of the projection 12b of the rotor core 12. In this embodiment, the tip of the position regulating pin 110 and the tip of the projection 12b of the rotor core 12 are not in contact, but the tip of the position regulating pin 110 and the tip of the projection 12b of the rotor core 12 may be in contact. In other words, the tip of the position regulating pin 110 may be brought into contact with the tip of the projection 12b of the rotor core 12.

[0085] In this way, by inserting the position regulating pin 110 into the gap G between each of two adjacent magnets 13, the movement of the multiple magnets 13 in the circumferential direction can be suppressed, thereby regulating the position of the multiple magnets 13. As a result, the multiple magnets 13 can be positioned in the circumferential direction, so that they are placed at predetermined positions (angular positions) in the circumferential direction of the rotor core 12. Thus, the position regulating pin 110 functions as a positioning pin that positions the rotor core 12 in the circumferential direction.

[0086] Furthermore, in the process of inserting the position regulating pin 110 into the gap G, the position regulating pin 110 is brought into contact with the respective sides of two adjacent magnets 13. This allows the magnets 13 to be supported by the position regulating pin 110, thereby ensuring the circumferential positioning of multiple magnets 13.

[0087] Although not shown in the figures, multiple position regulating pins 110 are provided in each of the multiple gaps G along the axial direction of the rotor core 12. Specifically, two position regulating pins 110 are provided in each gap G along the axial direction of the rotor core 12. Therefore, in the process of inserting the position regulating pins 110 into the gaps G, two position regulating pins 110 are inserted into each gap G. As a result, each magnet 13 can be supported by the multiple position regulating pins 110 inserted into each gap G, thereby enabling more reliable circumferential positioning of the multiple magnets 13.

[0088] Next, as shown in Figure 12C, the fluid resin material 14L is injected into the mold 100 and cured to fix the multiple magnets 13 to the rotor core 12 (third step: magnet fixing step).

[0089] Specifically, with a position-regulating pin 110 inserted into the gap G between two adjacent magnets 13, a fluid resin material 14L is injected into the mold 100 through a gate (not shown) provided in the mold 100, filling the voids within the mold 100 with the fluid resin material 14L. The injected fluid resin material 14L fills the gap G between the two adjacent magnets 13 and covers the outer edges of the magnets 13. At this time, the position-regulating pin 110 is inserted into the gap G between the two adjacent magnets 13, and each magnet 13 remains supported by the position-regulating pin 110. Therefore, even if the fluid resin material 14L flows into the mold 100, the position of the magnets 13 does not shift.

[0090] After injecting the fluid resin material 14L into the mold 100, the fluid resin material 14L is cured. In this embodiment, since a thermosetting resin is used as the fluid resin material 14L, the fluid resin material 14L is cured by heating it. At this time, a position regulating pin 110 is inserted into the gap G between two adjacent magnets 13, so that the position of the magnets 13 is not displaced by stress caused by expansion or contraction when the fluid resin material 14L hardens.

[0091] In this way, by curing the fluid resin material 14L, the resin material 14L becomes a resin 14 of a predetermined shape, and the rotor core 12 and the multiple magnets 13 are integrated and fixed by the resin 14. The resin 14 formed in this way has a covering portion 14a that covers the ends of the outer surface of the magnets 13 and an embedded portion 14b that is embedded in the gap G.

[0092] Next, as shown in Figure 12D, the position regulating pin 110 is ejected from the gap G between two adjacent magnets 13 (fourth step: pin ejection step).

[0093] Specifically, all position regulating pins 110 are simultaneously slid outward in the radial direction of the rotor core 12. At this time, the position regulating pins 110 are retracted until their tips are located inside the position regulating pin housing 120. In this way, the position regulating pins 110 can be ejected from the gaps G between the two adjacent magnets 13.

[0094] As a result, a hole 15 is formed in the portion of the embedded part 14b of the resin 14 where the position regulating pin 110 was located. In other words, the hole 15 is the hole where the position regulating pin 110 was removed. Therefore, the shape of the hole 15 corresponds to the shape of the position regulating pin 110. In this embodiment, since the position regulating pin 110 is a rectangular pin, the hole 15 is a rectangular parallelepiped.

[0095] Furthermore, in this embodiment, when the position regulating pin 110 is inserted into the gap G, the position regulating pin 110 is in contact with each side surface of the two adjacent magnets 13. Therefore, when the position regulating pin 110 is removed from the gap G, the hole 15 reaches each side surface of the two adjacent magnets 13, and the side surfaces of each magnet 13 are exposed through the hole 15.

[0096] As described above, a rotor assembly can be manufactured in which multiple magnets 13 are fixed to the rotor core 12. Subsequently, the rotor 10 is completed by attaching the rotating shaft 11 to the insertion hole 12a of the rotor core 12 of the rotor assembly.

[0097] Next, the effects of the rotor 10 according to this embodiment will be explained in comparison with the comparative example rotor 10X. Figure 13 is a cross-sectional view of the comparative example rotor 10X. Figures 14A and 14B are diagrams illustrating the manufacturing method of the comparative example rotor 10X. Figure 14A shows the rotor core and magnet arrangement process, and Figure 14B shows the magnet fixing process.

[0098] As shown in Figure 13, in the comparative example rotor 10X, which is an SPM rotor, the magnets 13 are fixed to the rotor core 12X with resin 14X to prevent them from being scattered by centrifugal force. In addition, in the comparative example rotor 10X, a projection 12b is provided on the outer circumferential surface of the rotor core 12X. The projection 12b is inserted into the gap G between two adjacent magnets 13.

[0099] When manufacturing a comparative example rotor 10X with such a structure, as shown in Figure 14A, the rotor core 12X is placed in the mold 100X of an injection molding machine, and multiple magnets 13 are placed between the rotor core 12X and the mold 100X. Then, as shown in Figure 14B, a fluid resin material 14L is injected into the mold 100X and the resin material 14L is cured to fix the multiple magnets 13 to the rotor core 12X.

[0100] At this time, as shown in Figures 14A and 14B, the projections 12b of the rotor core 12X are inserted into the gap G between two adjacent magnets 13 to prevent the circumferential position (angular position) of the magnet 13 from shifting, and the magnets 13 and rotor core 12X are placed in the mold 100X. However, if the height of the projections 12b is reduced to suppress the cost increase of the rotor core 12X due to the projections 12b, the magnets 13 ride up onto the projections 12b when the fluid resin material 14L is injected into the mold 100X or when the resin material 14L is cured, and as a result the position of the magnets 13 shifts in the circumferential direction.

[0101] Therefore, in order to prevent the magnet 13 from riding up onto the protrusion 12b, the height of the protrusion 12b needs to be increased to a certain extent. For example, the height of the protrusion 12b needs to be at least half the length of the side surface of the magnet 13.

[0102] However, since the protrusion 12b is part of the rotor core 12X, which is a magnetic material, increasing the height of the protrusion 12b causes the magnetic flux of two adjacent magnets 13 to short-circuit through the protrusion 12b, reducing the amount of magnetic flux that the magnets 13 can provide to the stator. In other words, the amount of magnetic flux required for the rotor 10X decreases. As a result, the torque performance of the electric motor decreases. Also, increasing the height of the protrusion 12b increases the base material dimensions A (hoop width × feed pitch) of the electromagnetic steel sheet constituting the rotor core 12X by the amount of the height of the protrusion 12b, as shown in Figure 13, and thus increases the cost of the rotor core 12X.

[0103] In contrast, the method for manufacturing the rotor 10 according to this embodiment includes the steps of: placing the rotor core 12 and a plurality of magnets 13 arranged along the outer circumferential surface of the rotor core 12 in a mold 100; inserting position regulating pins 110 into the gaps G between two adjacent magnets 13 in the plurality of magnets 13; injecting a fluid resin material 14L into the mold 100 and hardening the resin material 14L to fix the plurality of magnets 13 to the rotor core 12; and discharging the position regulating pins 110 from the gaps G.

[0104] As described above, in the manufacturing method of the rotor 10 according to this embodiment, a fluid resin material 14L is injected into a mold 100 with a position regulating pin 110 inserted into the gap G between each of two adjacent magnets 13, and the resin material 14L is cured. This makes it possible to suppress the circumferential displacement of the multiple magnets 13 even if the height of the protrusions 12b of the rotor core 12 is low.

[0105] For example, even if the height of the projection 12b is less than half or less than one-third of the length of the side surface of the magnet 13, the magnet 13 is supported by the position regulating pin 110, so displacement of the magnet 13 in the circumferential direction can be suppressed. In particular, even if there is no projection 12b on the rotor core 12 (even if the height of the projection 12b = 0), displacement of the magnet 13 in the circumferential direction can be suppressed.

[0106] This allows the height of the protrusion 12b to be reduced, thereby suppressing short-circuiting of the magnetic flux of two adjacent magnets 13 flanking the protrusion 12b. Consequently, the reduction in the amount of magnetic flux of the magnets 13 due to the protrusion 12b can be suppressed. As a result, the reduction in the amount of magnetic flux of the rotor 10 can be suppressed, thus suppressing a decrease in the torque performance of the electric motor 1. Moreover, by reducing the height of the protrusion 12b, the base material dimensions B (hoop width × feed pitch) of the electromagnetic steel sheet constituting the rotor core 12 can be reduced, as shown in Figure 10. This also suppresses the cost increase of the rotor core 12 due to the protrusion 12b.

[0107] Furthermore, since the circumferential displacement of the magnet 13 can be suppressed, the magnet 13 can be positioned at a predetermined circumferential position (angle position) on the rotor core 12. This also suppresses a decrease in the torque performance of the electric motor 1 due to the circumferential displacement of the magnet 13.

[0108] As described above, the manufacturing method for the rotor 10 according to this embodiment makes it possible to manufacture a rotor 10 that can realize a high-performance electric motor 1 having high torque performance.

[0109] Furthermore, a rotor 10 manufactured by the manufacturing method of the rotor 10 according to this embodiment comprises a rotor core 12, a plurality of magnets 13 arranged on the outer circumferential surface of the rotor core 12 and aligned in the circumferential direction of the rotor core 12, and a resin 14 that fixes the plurality of magnets 13 to the rotor core 12. A gap G exists between each of two adjacent magnets 13, and the resin 14 has an embedded portion 14b which is a part embedded in the gap G, and a recessed hole 15 is formed in the embedded portion 14b.

[0110] (Modification) The electric motor 1 relating to this disclosure has been described above based on embodiments, but this disclosure is not limited to the above embodiments.

[0111] For example, in the above embodiment, all of the multiple holes 15 formed in the resin 14 of the rotor 10 were open, but this is not limited to this. Specifically, in a later process, an embedded member made of resin material or the like may be embedded in at least one of the multiple holes 15. When open holes 15 are formed in the resin 14, wind noise may be generated when the rotor 10 rotates at high speed due to the drive of the electric motor 1, but the generation of wind noise can be suppressed by filling the holes 15 with an embedded member. From the viewpoint of preventing wind noise, it is preferable to fill all of the holes 15 with an embedded member. In addition, one or more of the holes 15 may be filled with an embedded member in order to adjust the weight balance of the rotor 10. In addition to filling one or more of the holes 15 with an embedded member in order to adjust the weight balance of the rotor 10, one or more of the holes 15 may also be enlarged.

[0112] Furthermore, in the above embodiment, the surface on the rotor 10 where the magnet 13B and the rotor core 12 are in contact is cylindrical, but this is not limited to this. For example, as shown in the rotor 10B in Figure 15, the surface on which the magnet 13B and the rotor core 12B are in contact may be a flat surface. Specifically, the magnet 13B has a flat portion 13a as the surface facing the rotor core 12B. The magnet 13B may have a shape that forms a substantially D-shaped cross section in a plane perpendicular to the axis C of the rotation shaft 11 shown in Figure 15. The rotor core 12B also has a flat surface 12c as the surface facing the magnet 13B. Multiple magnets 13B are attached to the rotor core 12B. Therefore, the rotor core 12B may be substantially polygonal in a plane perpendicular to the axis C of the rotation shaft 11. In this modified example, eight magnets 13B are attached to the rotor core 12B. Therefore, the rotor core 12B has eight sides based on eight planes 12c in a plane perpendicular to the axis C of the rotation axis 11 shown in Figure 15. The rotor core 12B is substantially octagonal in a plane perpendicular to the axis C of the rotation axis 11. In the rotor 10B shown in Figure 15, the magnet 13B and the rotor core 12B are in contact with each other on their planes. As a result, the magnet 13B and the rotor core 12B are in contact more stably than in the embodiment exemplified above. In this modified example, as explained using Figures 12A to 12D, the position regulating pin is inserted into the gap G located between adjacent magnets 13B.

[0113] Furthermore, in the above embodiment, a sleeve bearing was used as the bearing that rotatably supports the rotating shaft 11, but the invention is not limited to this. Specifically, the bearing may be a ball bearing or the like. In this case, there may be one bearing or two bearings. For example, the rotating shaft 11 may be supported by two ball bearings.

[0114] Furthermore, although the rotor 10 has 8 poles in the above embodiment, it is not limited to this. Also, although the stator 20 has 12 slots in the above embodiment, it is not limited to this. The number of poles of the rotor 10 and the number of slots of the stator 20 can be any number.

[0115] Furthermore, in the above embodiment, the windings 22 of the stator 20 were wound around the stator core 21 in a concentrated winding manner, but this is not the only possible configuration. For example, the windings 22 of the stator 20 may be wound around the stator core 21 in a distributed winding manner.

[0116] Furthermore, in the above embodiment, the electric motor 1 was a double-shaft motor in which each end of the rotating shaft 11 protrudes from the first housing ring 51 and the second housing ring 52, respectively, but it is not limited to this. Specifically, the electric motor 1 may be a single-shaft motor in which only one end of the rotating shaft 11 protrudes from only one of the first housing ring 51 and the second housing ring 52.

[0117] Furthermore, although the electric motor 1 in the above embodiment was a molded motor, it is not limited to this. The technology of this disclosure can be applied to motors other than molded motors. In other words, the technology of this disclosure can also be applied to motors in which the stator 20 is not covered with molded resin 60.

[0118] Furthermore, although the electric motor 1 in the above embodiment was a brushless motor, it is not limited to this. The technology disclosed herein can also be applied to brushed motors that use brushes.

[0119] Furthermore, although the above embodiment describes the case in which the electric motor 1 is applied to the fan motor of an air conditioner, which is an air conditioning device, it is not limited to this. For example, the electric motor 1 in the above embodiment can be used in various electrical devices such as household electrical appliances and industrial electrical appliances.

[0120] Furthermore, this disclosure also includes forms obtained by applying various modifications to the above embodiments and their respective modifications that a person skilled in the art could conceive, as well as forms realized by arbitrarily combining the components and functions of the embodiments and their respective modifications without departing from the spirit of this disclosure. In addition, this disclosure also includes any combination of two or more claims from the multiple claims described in the claims of this application, provided that they are not technically contradictory. For example, if the cited claims described in the claims of this application are made into a multi-claim or multi-multi-claim so as to refer to all of the higher-level claims without technically contradictory, then all combinations of claims included in that multi-claim or multi-multi-claim are also included in this disclosure.

[0121] The electric motor described herein can be widely used in various devices, including air conditioners.

[0122] 1. Electric motor 10, 10A, 10B Rotor 11 Rotating shaft 11a First end 11b Second end 12, 12A, 12B Rotor core 12a Through hole 12b Projection 12c Flat surface 13, 13B Magnet 13a Flat surface 14 Resin 14a Covering part 14b Embedded part 14L Resin material 15 Hole 20 Stator 21 Stator core 21a Teeth 22 Winding 23 Insulator 30 Sleeve bearing 40 Holder 51 First housing ring 51a, 52a Through hole 52 Second housing ring 60 Molded resin 71 First slinger 72 Second slinger 80 Vibration damping ring 100 Mold 110 Position regulating pin 120 Position regulating pin housing

Claims

1. A method for manufacturing a rotor, comprising the steps of: placing a rotor core and a plurality of magnets arranged along the outer circumferential surface of the rotor core into a mold; inserting a position-regulating pin into the gap between each of two adjacent magnets among the plurality of magnets; injecting a fluid resin material into the mold and hardening the resin material to fix the plurality of magnets to the rotor core; and discharging the position-regulating pin from the gap.

2. The method for manufacturing a rotor according to claim 1, wherein in the step of inserting the position regulating pin into the gap, the position regulating pin is brought into contact with each of the two adjacent magnets.

3. The method for manufacturing a rotor according to claim 1, wherein, in the step of inserting the position regulating pins into the gaps, a plurality of position regulating pins are inserted into each of the plurality of gaps along the axial direction of the rotor core.

4. The outer circumferential surface of the rotor core is provided with a projection located in the gap between each of the two adjacent magnets, wherein the height of the projection is less than half the thickness of the side surface of the magnet, the method for manufacturing a rotor according to any one of claims 1 to 3.

5. A rotor comprising: a rotor core; a plurality of magnets arranged on the outer circumferential surface of the rotor core and aligned in the circumferential direction of the rotor core; and a resin for fixing the plurality of magnets to the rotor core, wherein a gap exists between each of two adjacent magnets among the plurality of magnets, and the resin has an embedded portion which is a part embedded in the gap, and a recessed hole is formed in the embedded portion.

6. The rotor according to claim 5, wherein the holes reach the respective sides of the two adjacent magnets, and the sides are exposed.

7. The rotor according to claim 5, wherein in each of the plurality of embedded portions, a plurality of holes are formed along the axial direction of the rotor core.

8. The rotor according to any one of claims 5 to 7, wherein the outer circumferential surface of the rotor core is provided with a projection located in the gap between each of the two adjacent magnets, and the height of the projection is less than half the thickness of the side surface of the magnet.

9. The rotor according to any one of claims 5 to 7, wherein an embedded member is embedded in one of the multiple holes.

10. The rotor according to any one of claims 5 to 7, wherein the outer circumferential surface of the rotor core includes a cylindrical surface, and each of the plurality of magnets is a fan-segment type magnet.

11. An electric motor comprising a rotor according to any one of claims 5 to 7, and a stator that generates a magnetic force acting on the rotor.

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