Rotor, motor, and method for producing rotor

Abstract

This rotor is provided with: a rotating shaft that extends in the axial direction in which the axial center extends; a rotor core through which the rotating shaft is inserted; and a plurality of magnets that are radially disposed around the rotating shaft inside the rotor core. The rotor core and the plurality of magnets are fixed by resin; however, the radially outer surface of each of the plurality of magnets is not covered with the resin.

Description

Rotor, motor, and method of manufacturing the rotor

[0001] The present disclosure relates to a rotor, a motor including the rotor, and a method for manufacturing the rotor.

[0002] 2. Description of the Related Art Motors are used in a variety of electrical appliances, such as household appliances and industrial appliances. For example, air conditioners use fan motors in which a rotary fan is attached to the rotating shaft of the motor.

[0003] An interior permanent magnet (IPM) motor is known as a motor having a rotor with a permanent magnet embedded in a rotor core, in which multiple magnets are embedded in the rotor core. A conventional motor of this type is a spoke-type IPM motor having a rotor with multiple magnets arranged in a spoke-like (radial) pattern (see, for example, Patent Documents 1 and 2).

[0004] In the IPM motors disclosed in Patent Documents 1 and 2, the rotor has a rotor core that includes an inner core through which a rotating shaft is inserted and an outer core that holds multiple magnets. The outer core is divided into multiple split cores along the circumferential direction. A magnet is disposed in the gap between two adjacent split cores. The inner core, outer core (multiple split cores), and multiple magnets are fixed together by a molded resin formed by injection molding.

[0005] However, in the IPM motor structures disclosed in Patent Documents 1 and 2, the outer core is composed of multiple split cores, which increases the number of parts, reducing rotor assembly precision and potentially degrading motor performance. Specifically, when the inner core, outer core (multiple split cores), and multiple magnets are injection-molded and fixed with resin, the magnets inserted between two adjacent split cores may shift from their intended positions. This results in cogging torque and torque ripple, reducing motor performance.

[0006] In particular, when a rotor is manufactured by injection molding a pre-magnetized magnet inserted into the gap between two split cores, the following problem occurs: Due to manufacturing tolerances, a clearance exists between the split cores and the magnets. In a spoke-type IPM motor, multiple magnets are arranged with their main surfaces facing each other, resulting in a large magnetic repulsion force. As a result, when a pre-magnetized magnet is inserted into the gap between the two split cores, the split cores and magnets are likely to shift from their intended positions. This results in cogging torque and torque ripple.

[0007] In this case, it is possible to magnetize the magnets after assembling the pre-magnetized magnets into the rotor core. However, when manufacturing a rotor, it is difficult to magnetize multiple magnets arranged radially (like spokes) to saturation all at once. Therefore, one manufacturing method involves magnetizing only specific magnets in one magnetization run, and then magnetizing the rotor core multiple times while it is rotating. This manufacturing method not only reduces production takt time, but also poses the risk of applying an inverse magnetic field (demagnetizing magnetic field) to magnets that are not to be magnetized, resulting in a decrease in motor performance.

[0008] Instead of completely separating the split cores, it has been considered to connect two adjacent split cores with a connecting portion. However, in this case, the boundary between the connecting portion and the split cores is weak. Therefore, when a magnet is inserted into the gap between two adjacent split cores, stress is applied to the boundary between the connecting portion and the split cores, which may cause the split cores to deform and move around the boundary. This may ultimately result in the split cores and magnets being displaced from their intended positions. In particular, when a rotor is fabricated by inserting pre-magnetized magnets into the gap between two split cores, the repulsive force between the two opposing magnets causes the split cores to deform and move around the boundary between the connecting portion and the split cores as a fulcrum. This may result in the split cores and magnets being displaced from their intended positions.

[0009] JP 2022-117166 A JP 2023-92367 A

[0010] The present disclosure has been made to solve these problems, and aims to provide a spoke-type IPM motor having a rotor in which multiple radially arranged magnets and a rotor core are fixed with resin, in which the magnets are precisely positioned in predetermined positions.

[0011] In order to achieve the above object, a rotor according to one embodiment of the present disclosure comprises a rotating shaft extending in the axial direction along which the axis extends, a rotor core through which the rotating shaft is inserted, and a plurality of magnets arranged radially inside the rotor core around the rotating shaft, wherein the rotor core and the plurality of magnets are fixed with resin, and the radial outer surface of each of the plurality of magnets is not covered with the resin.

[0012] The rotor core has an inner core through which the rotating shaft passes, and an outer core that is positioned radially outward of the inner core and holds the multiple magnets, and the inner core, the outer core, and the multiple magnets are fixed by the resin, and the outer core has a plurality of first cores arranged in a ring shape around the rotating shaft, and a pair of second cores that sandwich the multiple first cores from the axial direction, and each of the multiple magnets is inserted into the gap between two adjacent first cores of the multiple first cores, and each of the pair of second cores has a plurality of core portions that correspond one-to-one to the multiple first cores, and a plurality of connecting portions that sequentially connect the multiple core portions in a circumferential direction around the rotating shaft, and each of the multiple connecting portions preferably connects a portion of two adjacent core portions of the multiple core portions other than the radially outer ends thereof.

[0013] Each of the plurality of connecting portions may connect radially inner ends of the two adjacent core portions to each other.

[0014] Each of the plurality of core portions preferably has a protrusion that protrudes in the circumferential direction from the radially outer end portion.

[0015] It is preferable that each of the plurality of first cores has a protrusion that protrudes in the circumferential direction from the radially outer end portion.

[0016] It is preferable that the outer core has a plurality of communication holes that communicate with the plurality of first cores and the plurality of core portions in the second core, respectively, and that the resin is filled into the plurality of communication holes.

[0017] In addition, another aspect of a rotor according to the present disclosure comprises a rotating shaft extending in the axial direction along which the axis extends, a rotor core through which the rotating shaft is inserted, and a plurality of magnets arranged radially inside the rotor core around the rotating shaft, wherein the rotor core and the plurality of magnets are fixed with resin, the rotor core has a plurality of cores arranged in a ring shape around the rotating shaft, each of the plurality of cores having a protrusion protruding circumferentially from its radially outer end, and each of the plurality of magnets being inserted into a gap between two adjacent cores in the plurality of cores and in contact with the protrusion.

[0018] The radially outer surface of each of the plurality of magnets may be covered with the resin.

[0019] A motor according to one aspect of the present disclosure includes any of the rotors described above and a stator that generates a magnetic force acting on the rotor.

[0020] A rotor manufacturing method of a first aspect according to the present disclosure includes the steps of setting a rotor core in a mold, inserting multiple magnets radially into the rotor core set in the mold, and injecting resin into the mold to mold the rotor core and the multiple magnets, wherein in the step of inserting the multiple magnets into the rotor core, the mold is brought into contact with the radial outer surfaces of the multiple magnets.

[0021] A method of manufacturing a rotor according to a second aspect of the present disclosure includes the steps of: setting a rotor core in a mold; inserting a plurality of magnets radially into the rotor core set in the mold; and injecting resin into the mold to mold the rotor core and the plurality of magnets, wherein the rotor core has an inner core through which a rotational axis passes; and an outer core positioned radially outward of the inner core and holding the plurality of magnets, the outer core having a plurality of first cores arranged in an annular shape around the rotational axis; and a pair of second cores sandwiching the plurality of first cores in the axial direction of the rotational axis, each of the pair of second cores having a plurality of core portions corresponding one-to-one to the plurality of first cores, and a front core. The rotor core has a plurality of connecting portions that sequentially connect the plurality of core portions in a circumferential direction around the rotating shaft, and each of the plurality of connecting portions connects two adjacent core portions among the plurality of core portions at a point other than the radially outer ends thereof, and in the process of setting the rotor core in the mold, the inner core and the outer core are set in the mold, and in the process of inserting the plurality of magnets into the rotor core, each of the plurality of magnets is inserted into the gap between two adjacent first cores among the plurality of first cores, and in the process of injecting resin into the mold to mold the rotor core and the plurality of magnets, the inner core, the outer core and the plurality of magnets are molded integrally using the resin.

[0022] In the step of inserting the plurality of magnets into the rotor core, the plurality of magnetized magnets may be inserted into the rotor core.

[0023] In addition, a rotor manufacturing method of a third aspect according to the present disclosure includes the steps of setting a rotor core in a mold, inserting a plurality of magnets radially into the rotor core set in the mold, and injecting resin into the mold to mold the rotor core and the plurality of magnets, wherein the rotor core has a plurality of cores arranged in a ring shape around the rotation axis, and each of the plurality of cores has a protrusion protruding circumferentially from its radially outer end, and in the step of inserting the plurality of magnets into the rotor core, each of the plurality of magnets is inserted into the gap between two adjacent cores in the plurality of cores, and the mold is brought into contact with the circumferential side of the protrusion of the core.

[0024] According to the present disclosure, in a spoke-type IPM motor having a rotor in which multiple radially arranged magnets and a rotor core are fixed with resin, it is possible to obtain a rotor and motor in which the magnets are precisely positioned in predetermined positions.

[0025] FIG. 1 is an external perspective view of a motor according to an embodiment. FIG. 2 is a cross-sectional view of the motor according to the embodiment. FIG. 3 is a perspective view of a rotor according to the embodiment. FIG. 4 is an exploded perspective view of the rotor according to the embodiment. FIG. 5 is a cross-sectional perspective view of the rotor according to the embodiment, taken along a plane that passes through a pair of magnets facing each other across the rotation axis and is parallel to the rotation axis. FIG. 6 is a cross-sectional perspective view of the rotor according to the embodiment, taken along a plane that passes through a first core of the outer core and is parallel to the rotation axis. FIG. 7 is a cross-sectional view of the rotor according to the embodiment, taken along a plane that passes through the first core of the outer core and is perpendicular to the rotation axis. FIG. 8 is a cross-sectional view of the rotor according to the embodiment, taken along a plane that passes through a second core of the outer core and is perpendicular to the rotation axis. FIG. 9 is an exploded perspective view of an outer core used in a rotor core in a rotor according to an embodiment. FIG. 10 is a perspective view of an outer core in which an outer connecting portion and an inner connecting portion are provided on the core portion of the second core. FIG. 11 is a view for explaining a method of manufacturing a rotor according to an embodiment. FIG. 12 is a cross-sectional view showing the rotor core and magnets set in a mold. Fig. 13 is an enlarged cross-sectional view of the rotor core and magnet set in a mold, Fig. 14 is a cross-sectional view showing the rotor core and magnet set in a mold in a rotor manufacturing method according to a modified example, and Fig. 15 is a cross-sectional view of the rotor according to the modified example.

[0026] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the superordinate concept of the present disclosure will be described as optional components.

[0027] Each figure is a schematic diagram and is not necessarily an exact representation. Therefore, the scales and the like are not necessarily the same in each figure. In all figures, the same reference numerals are used to denote substantially the same components, and redundant explanations will be omitted or simplified.

[0028] In this specification, the terms "up" and "down" do not necessarily refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition. In this embodiment, for convenience, the direction in which the axis C of the rotating shaft 10 extends is defined as the up-down direction. However, this up-down direction may differ from the actual up-down direction depending on the usage state of the motor 1, etc. In this embodiment, the radial direction of the stator 2 and the rotor 3 is defined as the "radial direction," and the rotation direction of the rotor 3 is defined as the "circumferential direction." In other words, the direction perpendicular to the axis C of the rotating shaft 10 of the rotor 3 is defined as the "radial direction," and the direction orbiting the axis C of the rotating shaft 10 is defined as the "circumferential direction." The direction in which the axis C of the rotating shaft 10 extends (the longitudinal direction of the rotating shaft 10) is defined as the "axial direction."

[0029] (Embodiment) The configuration of a motor 1 according to an embodiment will be described with reference to Figures 1 and 2. Figure 1 is a perspective view of the appearance of the motor 1 according to the embodiment. Figure 2 is a cross-sectional view of the motor 1 according to the embodiment.

[0030] 2 , the motor 1 includes a stator 2 and a rotor 3 disposed opposite the stator 2. The motor 1 further includes a first bearing 4, a second bearing 5, a first bracket 6, and a second bracket 7.

[0031] 1 and 2, the motor 1 is a molded motor in which the stator 2 is covered with a molding resin 8. The motor 1 is also a brushless motor that does not use brushes.

[0032] 2 , the stator 2 is disposed opposite the rotor 3 with a small air gap between them. The stator 2 is disposed so as to surround the rotor core 20 of the rotor 3. In other words, the motor 1 is an inner rotor type motor in which the rotor 3 is disposed inside the stator 2.

[0033] The stator 2 generates a magnetic force that acts on the rotor 3. Specifically, the stator 2 is configured so that north and south poles are generated alternately in the circumferential direction on an air gap surface that faces a rotor core 20 of the rotor 3. The stator 2 and the rotor 3 form a magnetic circuit. The stator 2 has a stator core 2a and a winding 2b.

[0034] The stator core 2a of the stator 2 generates a magnetic force for rotating the rotor 3. The stator core 2a is, for example, a laminated body in which a plurality of steel plates are stacked in the direction in which the axis C of the rotating shaft 10 extends. Each of the plurality of steel plates is a magnetic material. Each of the plurality of steel plates is, for example, a punched electromagnetic steel plate formed into a predetermined shape. The stator core 2a is not limited to a laminated body of a plurality of steel plates, and may also be a bulk body made of a magnetic material.

[0035] The stator core 2a has a plurality of teeth that protrude toward the rotor 3. The plurality of teeth are arranged to protrude toward the axis C of the rotating shaft 10. The plurality of teeth are arranged at equal intervals in the circumferential direction, with slots formed between two adjacent teeth. The plurality of teeth extend radially in a direction perpendicular to the axis C of the rotating shaft 10 (radial direction).

[0036] The winding 2b is an armature winding of the stator 2. The winding 2b is a winding coil wound around the stator core 2a as a stator coil. The winding 2b is wound around multiple teeth of the stator core 2a. Specifically, the winding 2b is wound around each of the multiple teeth via an insulator 2c. In other words, multiple windings 2b are wound around the stator 2. Each winding 2b is a concentrated winding coil wound around a corresponding tooth. Each winding 2b is housed in a slot in the stator core 2a.

[0037] When current is applied to the windings 2b, a magnetic force is generated from each of the multiple teeth of the stator core 2a. For example, the multiple windings 2b are electrically connected as a three-phase winding so that the rotor 3 rotates as a three-phase synchronous motor. In other words, the motor 1 in this embodiment is an interior permanent magnet synchronous motor (IPMSM). In this case, the multiple windings 2b are composed of unit coils for each of the three phases, U-phase, V-phase, and W-phase, which are electrically out of phase with each other by 120 degrees. In other words, the windings 2b attached to each tooth are energized and driven by three-phase alternating current that is applied to each of the U-phase, V-phase, and W-phase units. As a result, a main magnetic flux of the stator 2 is generated in each tooth.

[0038] The stator 2 is a molded stator covered with a molded resin 8. For example, the stator 2 can be covered with the molded resin 8 by injection molding. The molded resin 8 covers the outer portion of the stator 2 over the entire circumferential direction of the stator 2. Specifically, the molded resin 8 covers the outer portions of the stator core 2a and the windings 2b. The molded resin 8 forms a housing that contains the rotor 3. Specifically, the molded resin 8 is formed in a cylindrical shape with a bottom. As shown in FIG. 1 , the molded resin 8 forms the outer shell of the motor 1.

[0039] The molded resin 8 has a plurality of protruding portions that protrude radially outward. The protruding portions are the legs of the motor 1. The protruding portions function as mounting portions for mounting the motor 1 to an installation object. The molded resin 8 is made of an insulating resin material with excellent thermal conductivity, such as polyester resin or epoxy resin. The molded resin 8 is made of a thermosetting resin. In this embodiment, the molded resin 8 is made of unsaturated polyester (BMC (Bulk Molding Compound)), which is a thermosetting resin. Specifically, the molded resin 8 is made of white BMC.

[0040] As shown in Fig. 2, a circuit board 9 to which the windings 2b of the stator 2 are connected is embedded in the molded resin 8. In this case, the ends of the windings 2b of each phase are connected at winding connection portions of the circuit board 9. For example, the circuit board 9 is formed with pattern wiring for electrically connecting the plurality of windings 2b for each of the U, V, and W phases. The ends of the windings 2b of each phase are electrically connected to the pattern wiring of the circuit board 9 by solder or the like.

[0041] The rotor 3 rotates due to the magnetic force generated in the stator 2. Specifically, the rotor 3 has a rotating shaft 10. The rotor 3 rotates around an axis C of the rotating shaft 10 as the center of rotation.

[0042] The rotor 3 generates a magnetic force that acts on the stator 2. The rotor 3 has a configuration in which N and S poles that form the main magnetic flux are repeated multiple times along the circumferential direction. The direction of the main magnetic flux generated by the rotor 3 is perpendicular to the direction in which the axis C of the rotating shaft 10 extends (radial direction).

[0043] As shown in Fig. 2, the rotor 3 is disposed opposite the stator 2 with an air gap between them. As will be described in detail later, the rotor 3 has a rotating shaft 10, a rotor core 20, and a magnet 30. The rotor 3 is an IPM rotor in which the magnet 30 is embedded in the rotor core 20. Therefore, the motor 1 is an IPM motor.

[0044] The rotating shaft 10 of the rotor 3 is supported by a first bearing 4 and a second bearing 5. The first bearing 4 and the second bearing 5 work as a pair of bearings to rotatably support the rotating shaft 10. In this way, the rotating shaft 10 is held in a rotatable state by the first bearing 4 and the second bearing 5. This allows the rotor 3 to rotate relative to the stator 2. As an example, the first bearing 4 and the second bearing 5 are ball bearings. However, this is not limiting. The first bearing 4 and the second bearing 5 may be thrust bearings or the like.

[0045] The first bearing 4 is held by a first bracket 6. The first bracket 6 is fixed to one end of the molded resin 8 in the direction in which the axis C of the rotating shaft 10 extends. The second bearing 5 is held by a second bracket 7. The second bracket 7 is fixed to the other end of the molded resin 8 in the direction in which the axis C of the rotating shaft 10 extends.

[0046] The first bracket 6 and the second bracket 7 are made of a metal material such as iron, for example. For example, the first bracket 6 and the second bracket 7 are made of a metal plate with a uniform thickness.

[0047] In the motor 1 configured as described above, when current is applied to the winding 2b of the stator 2, a field current flows through the winding 2b, generating a magnetic field. This generates magnetic flux that flows from the stator 2 toward the rotor 3. Specifically, magnetic flux is generated from each of the multiple teeth of the stator core 2a of the stator 2 toward the rotor core 20 of the rotor 3. Meanwhile, in the rotor 3, magnetic flux that passes through the stator 2 is generated by the magnet 30 embedded in the rotor core 20. A magnetic force generated by the interaction between the magnetic flux generated by the stator 2 and the magnetic flux generated by the magnet 30 of the rotor 3 becomes a torque that rotates the rotor 3, and the rotor 3 then rotates.

[0048] The motor 1 is used in, for example, an air conditioner or other air conditioner. Specifically, the motor 1 is mounted in an outdoor unit of the air conditioner as a fan motor having a rotary fan attached to a rotary shaft 10.

[0049] The detailed configuration of the rotor 3 will be described with reference to FIG. 2 and FIGS. 3 to 10 . FIG. 3 is a perspective view of the rotor 3 according to the embodiment. FIG. 4 is an exploded perspective view of the rotor 3 according to the embodiment. FIG. 5 is a cross-sectional perspective view of the rotor 3 according to the embodiment, taken along a plane that passes through a pair of magnets 30 facing each other across the rotation shaft 10 and is parallel to the rotation shaft 10. FIG. 6 is a cross-sectional perspective view of the rotor 3 according to the embodiment, taken along a plane that passes through the first core 21 of the outer core 20b and is parallel to the rotation shaft 10. FIG. 7 is a cross-sectional view of the rotor 3 according to the embodiment, taken along a plane that passes through the first core 21 of the outer core 20b and is perpendicular to the rotation shaft 10. FIG. 8 is a cross-sectional view of the rotor 3 according to the embodiment, taken along a plane that passes through the second core 22 of the outer core 20b and is perpendicular to the rotation shaft 10. FIG. 9 is an exploded perspective view of the outer core 20b used in the rotor core 20 in the rotor 3 according to the embodiment. FIG. 10 is a perspective view of an outer core 20b in which an outer connecting portion 22b and an inner connecting portion 22b are provided on the core portion 22a of the second core 22. As shown in FIG.

[0050] As shown in FIGS. 2 to 6, the rotor 3 includes a rotating shaft 10, a rotor core 20 through which the rotating shaft 10 is inserted, and a plurality of magnets 30 held by the rotor core 20.

[0051] The rotating shaft 10 has an axis C that is the center when the rotor 3 rotates. The rotating shaft 10 extends in the direction in which the axis C extends. The rotating shaft 10 is a long shaft. The rotating shaft 10 is a metal rod made of a metal material such as SUS (Steel Use Stainless Steel). The rotating shaft 10 is fixed to the rotor core 20. Specifically, the rotating shaft 10 penetrates the rotor core 20. The rotating shaft 10 is fixed to the rotor core 20 so as to extend on both sides of the rotor core 20 in the direction in which the axis C extends.

[0052] 2, one end of the rotating shaft 10 protrudes to the outside through the through-hole of the first bracket 6. The portion of the rotating shaft 10 protruding from the first bracket 6 serves as an output shaft. For example, a load such as a rotary fan is attached to one end of the rotating shaft 10.

[0053] The other end of the rotating shaft 10 does not protrude to the outside from the second bracket 7, but may protrude to the outside from the second bracket 7. In other words, both ends of the rotating shaft 10 may protrude from the first bracket 6 and the second bracket 7, respectively.

[0054] As shown in Fig. 2, the rotor core 20 is disposed so as to face the stator core 2a of the stator 2 with an air gap therebetween. As shown in Figs. 4 to 8, the rotor core 20 has an inner core 20a and an outer core 20b. As shown in Fig. 7, the inner core 20a holds the rotating shaft 10. The outer core 20b holds a plurality of magnets 30.

[0055] The inner core 20a is located radially inward of the outer core 20b. In other words, the inner core 20a is an inner core located more inward than the outer core 20b.

[0056] The rotating shaft 10 passes through the inner core 20a. The rotating shaft 10 is fixed to the inner core 20a. Specifically, a through hole 20a1 is formed in the inner core 20a. The rotating shaft 10 is fixed to the inner core 20a by being press-fitted or shrink-fitted into the through hole 20a1. As shown in FIG. 4 , the inner core 20a is a cylindrical member having an overall cylindrical shape.

[0057] 5 to 7, the outer core 20b is located radially outward from the inner core 20a. In other words, the outer core 20b is an outer core located further outward than the inner core 20a. Specifically, the outer core 20b surrounds the inner core 20a.

[0058] Each of the inner core 20a and the outer core 20b is a laminate formed by stacking a plurality of steel plates, which are magnetic materials, in the direction of extension of the axial center C of the rotating shaft 10. Each of the plurality of steel plates in each of the inner core 20a and the outer core 20b is, for example, a punched electromagnetic steel plate formed into a predetermined shape. In each of the inner core 20a and the outer core 20b, the plurality of steel plates are fixed to each other by, for example, crimping or welding. The inner core 20a and the outer core 20b are fixed to each other by the resin 40 interposed between the inner core 20a and the outer core 20b.

[0059] The steel plates constituting the inner core 20a and the outer core 20b may be formed simultaneously, for example, by simultaneously punching a single steel plate. In other words, the steel plates constituting the inner core 20a and the steel plates constituting the outer core 20b may be formed using the same mold. This can improve manufacturing costs and assembly takt time. It can also simplify the structure of the injection molding mold used to integrate the inner core 20a and the outer core 20b with the resin 40.

[0060] 3 to 9, the outer core 20b has a plurality of first cores 21 and a pair of second cores 22 that sandwich the plurality of first cores 21 in the direction in which the axis C of the rotating shaft 10 extends. The first cores 21 and the second cores 22 have different shapes. In other words, the outer core 20b is composed of two types of cores, the first cores 21 and the second cores 22, which have different shapes.

[0061] Each of the first core 21 and the second core 22 constituting the outer core 20b is a laminated body formed by stacking multiple steel plates in the direction of the axis C of the rotating shaft 10. The multiple first cores 21 form the main magnetic pole portions of the outer core 20b. Therefore, the thickness (height in the direction of the axis C of the rotating shaft 10) of each first core 21 is greater than the thickness of each second core 22. Specifically, the number of steel plates constituting the first core 21 is greater than the number of steel plates constituting the second core 22. As an example, if the thickness of each of the steel plates constituting the first core 21 and the second core 22 is 0.5 mm, the first core 21 is composed of 96 steel plates (48 mm thick), and the second core 22 is composed of four steel plates (2 mm thick). Since one of the purposes of the second core 22 is to ensure the strength of the entire outer core 20b, the fewer steel plates used for the second core 22, the better.

[0062] Each of the multiple first cores 21 constitutes a magnetic pole portion of the rotor core 20. As shown in FIG. 7 , the multiple first cores 21 are arranged in an annular shape around the rotating shaft 10. The multiple first cores 21 are divided cores that are arranged separately from each other in the circumferential direction. In this embodiment, ten first cores 21 are arranged in an annular shape. Each of the multiple first cores 21 has the same shape and size. In other words, each of the multiple first cores 21 is the same component. Each of the multiple first cores 21 has a substantially sector shape in a plan view. In this case, as shown in FIG. 7 , the multiple first cores 21, each of which is substantially sector-shaped, are arranged so that the overall shape is circular.

[0063] 7 , the multiple first cores 21 are arranged such that a gap GP exists between two adjacent first cores 21. Each of the multiple magnets 30 is inserted into the gap GP. In other words, the gap GP forms a part of the magnet insertion hole 23 in the rotor core 20.

[0064] As shown in Figures 7 and 9, each of the multiple first cores 21 has a protrusion 21a that protrudes circumferentially from its radially outer end. The protrusion 21a is an outer protrusion provided on the outer peripheral end of the first core 21. The protrusions 21a are provided on both radially outer ends of each first core 21. By providing the protrusions 21a on the first core 21, it is possible to prevent the magnet 30 from falling off the outer core 20b. In other words, the protrusions 21a are magnet holding protrusions that hold the magnet 30 to the outer core 20b. The protrusions 21a function as stoppers that prevent the magnet 30 from jumping out of the outer core 20b.

[0065] 8 and 9 , each of the pair of second cores 22 sandwiching the plurality of first cores 21 is spoke-shaped. Each of the pair of second cores 22 has a plurality of core portions 22a and a plurality of connecting portions 22b that sequentially connect the plurality of core portions 22a. The plurality of core portions 22a and the plurality of connecting portions 22b are integrally formed. In other words, the second core 22 can be obtained by stacking a plurality of steel plates, each having a portion corresponding to the core portions 22a and a portion corresponding to the connecting portions 22b.

[0066] As shown in Fig. 9, the multiple core portions 22a in the second core 22 correspond one-to-one to the multiple first cores 21. Specifically, when viewed from the direction of the axis C of the rotating shaft 10, the shape of each of the multiple core portions 22a is the same as the shape of each of the multiple first cores 21. Since the shape of the first core 21 in a plan view is substantially fan-shaped, the shape of each core portion 22a in a plan view is also substantially fan-shaped. Each of the multiple core portions 22a is in contact with a corresponding one of the multiple first cores 21.

[0067] Each of the multiple core portions 22a has a protrusion 22a1 protruding in the circumferential direction from its radially outer end. The protrusion 22a1 is an outer protrusion provided at the outer peripheral end of the core portion 22a. The protrusion 22a1 is provided at both radially outer ends of each core portion 22a. By providing the protrusion 22a1 on the core portion 22a, it is possible to prevent the magnet 30 from falling off the outer core 20b. In other words, the protrusion 22a1 on the core portion 22a is a magnet holding protrusion that holds the magnet 30 to the outer core 20b, similar to the protrusion 21a on the first core 21 (split core). The protrusion 22a1 on the core portion 22a functions as a stopper that prevents the magnet 30 from jumping out of the outer core 20b.

[0068] The protrusions 22a1 of the core portion 22a correspond one-to-one to the protrusions 21a of the first core 21 (split core). Specifically, when viewed from the direction of the axis C of the rotating shaft 10, the shape of the protrusions 22a1 of the core portion 22a is the same as the shape of the protrusions 21a of the first core 21.

[0069] Each of the plurality of connecting portions 22 b connects two adjacent core portions 22 a among the plurality of core portions 22 a. That is, each connecting portion 22 b is a connecting bridge connecting one of two adjacent core portions 22 a to the other. Specifically, each of the plurality of connecting portions 22 b connects two circumferentially adjacent core portions 22 a.

[0070] Each of the multiple connecting portions 22b connects two adjacent core portions 22a at locations other than their radially outer ends. As shown in FIGS. 8 and 9 , the connecting portion 22b is provided radially inward on the side end surface of the core portion 22a. Specifically, the connecting portion 22b is an inner connecting portion provided at the radially inner end of the side end surface of the core portion 22a. That is, each connecting portion 22b connects the radially inner ends of two adjacent core portions 22a (specifically, the tips of the core portions 22a). The connecting portion 22b is located on the opposite side of the inner core 20a from the end face of the inner core 20a in the direction along the axis C of the rotating shaft 10. The connecting portion 22b is located radially outward from the inner surface of the inner core 20a in the radial direction intersecting the axis C of the rotating shaft 10. The connecting portion 22b is linear. However, this is not limited thereto. For example, the connecting portion 22b may be arc-shaped.

[0071] 5 and 8, through holes HL are formed in the second core 22. Each through hole HL is an open area surrounded by two adjacent core portions 22a and the connecting portion 22b. Ten through holes HL are formed in the second core 22.

[0072] The magnet 30 is inserted into the through hole HL in the second core 22. In other words, the through hole HL, like the gap GP between two adjacent first cores 21, constitutes part of the magnet insertion hole 23 in the rotor core 20. As shown in Figures 4 and 5 , each of the multiple magnet insertion holes 23 in the rotor core 20 is formed by the through hole HL in the second core 22 and the gap GP between two adjacent first cores 21. The opening shape of the through hole HL in the second core 22 and the opening shape of the gap GP are the same.

[0073] As shown in FIGS. 5 to 8 , the multiple magnets 30 are arranged inside the rotor core 20. Specifically, as shown in FIG. 5 , each of the multiple magnets 30 is inserted into a magnet insertion hole 23 (through hole HL + gap GP) of the rotor core 20. That is, each of the multiple magnets 30 is inserted into a through hole HL in the second core 22 of the outer core 20b of the rotor core 20, and is also inserted into a gap GP between two adjacent first cores 21 in the outer core 20b. In this embodiment, ten magnet insertion holes 23 are provided in the rotor core 20, and therefore ten magnets 30 are used. The magnets 30 inserted into the magnet insertion holes 23 are held in the rotor core 20 by connecting portions 22b provided on the second core 22 and protrusions 21a provided on the first core 21.

[0074] The magnet 30 inserted into the magnet insertion hole 23 (through hole HL + gap GP) may be in contact with the first core 21 and the second core 22. Specifically, the magnet 30 may be in contact with the protrusion 21 a of the first core 21 and the protrusion of the core portion 22 a of the second core 22. Similar to the protrusion 21 a of the first core 21, the protrusion of the core portion 22 a of the second core 22 protrudes in the circumferential direction from the radially outer end.

[0075] 7 and 8, the magnets 30 are arranged in a ring shape around the rotating shaft 10. The magnets 30 are arranged radially around the rotating shaft 10. In other words, the motor 1 is a spoke-type IPM motor having a rotor 3 on which the magnets 30 are arranged in a spoke-like (radial) shape.

[0076] The multiple magnets 30 are arranged at equal intervals in the circumferential direction around the rotating shaft 10. The multiple magnets 30 are arranged so that the magnetic pole faces of the same polarity face each other between two adjacent magnets 30. In other words, between two adjacent magnets 30, the magnetic pole face that becomes the south pole of one magnet 30 faces the magnetic pole face that becomes the south pole of the other magnet 30, or the magnetic pole face that becomes the north pole of one magnet 30 faces the magnetic pole face that becomes the north pole of the other magnet 30.

[0077] Each of the multiple magnets 30 is a magnetized permanent magnet. Each magnet 30 is plate-shaped. The magnet 30 is a plate-shaped, substantially rectangular parallelepiped, and has a rectangular shape in plan view. Therefore, as shown in FIGS. 7 and 8 , the cross-sectional shape of the magnet 30 when cut along a plane perpendicular to the axis C of the rotating shaft 10 is rectangular. As shown in FIG. 5 , the cross-sectional shape of the magnet 30 when cut along a plane passing through the axis C of the rotating shaft 10 is also rectangular. As shown in FIGS. 7 and 8 , each magnet 30 is arranged so that its longitudinal direction is the radial direction of the rotor core 20 in plan view.

[0078] The magnet 30 protrudes from each of the upper and lower end faces of the outer core 20b in the direction of extension of the axis C of the rotating shaft 10. Specifically, both ends of the magnet 30 in the direction of extension of the axis C of the rotating shaft 10 protrude beyond the main surfaces of each of the pair of second cores 22. As a result, even if the corners of the magnet 30 are chamfered to improve the ease of insertion of the magnet 30 into the magnet insertion hole 23 and the resulting finish varies, the chamfered portions of the magnet 30 are positioned outside the outer core 20b, not inside. This prevents variations in magnetic flux due to the chamfered portions of the magnet 30. By having the magnet 30 protrude from the upper or lower end face of the outer core 20b, the magnetic flux of the magnet 30 can be easily detected by a Hall element disposed near the rotor 3.

[0079] As an example, the magnet 30 is a ferrite magnet made of sintered ferrite. However, the magnet 30 is not limited to a ferrite magnet. For example, the magnet 30 may be a rare earth magnet. In this case, a neodymium rare earth magnet whose main components are neodymium, iron, and boron (Nd—Fe—B) can be used as the magnet 30.

[0080] As shown in FIGS. 5 to 8 , the multiple magnets 30 are fixed to the rotor core 20 by a resin 40 (molded resin) formed by injection molding. That is, the rotor core 20 and the multiple magnets 30 are fixed by the resin 40. The rotor core 20 is composed of an inner core 20a and an outer core 20b. Therefore, the inner core 20a, the outer core 20b, and the multiple magnets 30 are fixed by the resin 40. Specifically, the magnets 30 are fixed by the resin 40 that has entered the gap GP between two adjacent first cores 21 in the outer core 20b. Instead of fixing the magnets 30 to the outer core 20b by the resin 40, the magnets 30 may be fixed to the outer core 20b by separately filling the gap between the magnets 30 and the first core 21 with an adhesive.

[0081] 5 to 7, the resin 40 is also present between the inner core 20a and the outer core 20b. This fixes the inner core 20a and the outer core 20b together with the resin 40. The portion of the resin 40 between the inner core 20a and the outer core 20b is substantially cylindrical in shape. In other words, the resin 40 has a cylindrical portion located between the inner core 20a and the outer core 20b.

[0082] As shown in Figure 7, knurled projections and recesses are formed on the outer peripheral surface of the inner core 20a in the circumferential direction. This increases the surface area of ​​the inner core 20a and allows the resin 40 to penetrate into the recesses of the projections and recesses. This allows the resin 40 to be firmly fixed to the inner core 20a by an anchor effect. As a result, misalignment between the inner core 20a and the resin 40 during rotation of the rotary shaft 10 can be prevented, preventing the inner core 20a from spinning freely.

[0083] 6 to 8, the resin 40 is also filled in the communication holes 24 provided in the outer core 20b. The communication holes 24 of the outer core 20b communicate with the through holes of each of the multiple first cores 21 and the through holes of each of the multiple core portions 22a in the second core 22. In other words, the resin 40 fills the through holes of each of the first cores 21 and the through holes of each of the core portions 22a. The cross-sectional shape of the communication holes 24 is, for example, circular. However, this is not limiting.

[0084] The communication holes 24 can also be used as pin holes into which mold pins are inserted when injection molding the rotor core 20 and the plurality of magnets 30. This makes it possible to easily position the outer core 20b in the mold by inserting the mold pins into the communication holes 24 when placing the outer core 20b in the mold for injection molding. If injection molding is performed with the mold pins inserted in the communication holes 24, the resin 40 will not be filled into the communication holes 24, and the communication holes 24 will become empty spaces.

[0085] As shown in Figures 3, 5, and 6, resin 40 not only fills the gap between inner core 20a and outer core 20b, but also covers the upper and lower portions of rotor core 20 and magnet 30. Resin 40 covering the upper and lower portions of rotor core 20 and magnet 30 is a disk-shaped plate having a through-hole that penetrates rotating shaft 10. Grooves or holes may be provided in the plate portion of resin 40 to adjust the balance of rotor 3. Fins or other structures may be provided on the lid of resin 40 to improve heat dissipation.

[0086] As described above, each of the magnets 30 is covered with the resin 40. However, the resin 40 does not cover the entirety of each magnet 30. Specifically, the radially outer surface 30a of each of the magnets 30 is not covered with the resin 40. In this embodiment, the outer surface 30a of each magnet 30 is not entirely covered with the resin 40, and the entire outer surface 30a is exposed. In other words, the outer surface 30a of each magnet 30 is an exposed surface. As shown in FIGS. 3 and 6 , the outer peripheral surface of the rotor 3 has an opening that exposes the outer surface 30a of each magnet 30. The opening has a rectangular slit shape that extends along the direction in which the axis C of the rotating shaft 10 extends. The outer surface 30a of each magnet 30 exposed from this opening is, like the shape of the opening, an elongated rectangle that extends in the direction of the axis C of the rotating shaft 10.

[0087] In this embodiment, the outer surface 30a of the magnet 30 is covered only by the protrusions 21a of the first core 21 and the protrusions 22a1 of the core portion 22a of the second core 22. In other words, only the ends of the outer surface 30a of the magnet 30 in the width direction are covered by the protrusions 21a and the protrusions 22a1.

[0088] The resin 40 is made of an insulating resin material with excellent thermal conductivity, such as polyester resin or epoxy resin. The resin 40 is made of a thermosetting resin. In this embodiment, the resin 40 is made of black BMC. The resin 40 may be made of polybutylene terephthalate (PBT) instead of BMC.

[0089] As described above, the rotor 3 according to this embodiment includes the rotor core 20 through which the rotating shaft 10 is inserted, and the plurality of magnets 30 arranged radially around the rotating shaft 10 inside the rotor core 20. The rotor core 20 and the plurality of magnets 30 are fixed together by the resin 40. However, the radially outer surface 30a of each of the plurality of magnets 30 is not covered with the resin 40. In other words, the outer surface 30a of the magnet 30 is exposed.

[0090] This allows for a larger output from the rotor 3. For this reason, the magnets 30 used in the rotor 3 can be ferrite magnets, which have a lower magnetic force than rare earth magnets and are less expensive, rather than expensive rare earth magnets with a high magnetic force. In other words, even if the magnets 30 are ferrite magnets, it is possible to achieve a rotor 3 that can obtain a predetermined output. This allows for a low-cost rotor 3 and motor 1.

[0091] In the rotor 3 according to this embodiment, the rotor core 20 includes an inner core 20a and an outer core 20b. The inner core 20a, the outer core 20b, and the plurality of magnets 30 are fixed together by resin 40. The outer core 20b includes a plurality of first cores 21 arranged in an annular shape around the rotating shaft 10 and a pair of second cores 22 that sandwich the plurality of first cores 21 from the direction of the axial center C of the rotating shaft 10. Each of the plurality of magnets 30 is inserted into a gap GP between two adjacent first cores 21 among the plurality of first cores 21. Each of the pair of second cores 22 includes a plurality of core portions 22a that correspond one-to-one to the plurality of first cores 21, and a plurality of connecting portions 22b that sequentially connect the plurality of core portions 22a in the circumferential direction. Each of the connecting portions 22b connects two adjacent core portions 22a among the plurality of core portions 22a at locations other than the radially outer ends.

[0092] The rotor 3 configured in this manner uses a plurality of first cores 21 (split cores) that are separated from one another, but the plurality of first cores 21 are sandwiched between a pair of second cores 22 that have a plurality of connecting portions 22b that sequentially connect the plurality of core portions 22a in the circumferential direction. As a result, even though separated first cores 21 (split cores) are used, the magnet 30 inserted in the gap GP between two adjacent first cores 21 can be held by the connecting portions 22b of the second cores 22.

[0093] Furthermore, the outer core 20b can be made into a single component by sandwiching a plurality of separated first cores 21 between a pair of second cores 22. Therefore, depending on the layout when punching the first cores 21 and the second cores 22 from a steel plate, multiple first cores 21 can be used, which can reduce material costs. Furthermore, because the outer core 20b can be treated as a single component, a decrease in assembly accuracy when assembling the rotor core 20 and the rotor 3 can be suppressed.

[0094] Furthermore, in the rotor 3 according to this embodiment, each of the plurality of connecting portions 22b connecting the plurality of core portions 22a connects the radially inner ends of two adjacent core portions 22a.

[0095] This configuration allows the second core 22 to connect two adjacent core portions 22a without connecting the radially outer ends of the two adjacent core portions 22a, thereby stabilizing the output of the motor 1. This will be described in detail below.

[0096] From the viewpoint of holding the magnet 30, as in the outer core 20bX shown in FIG. 10 , it is possible to provide each of a pair of second cores 22X sandwiching the separated first core 21 from above and below with not only a connecting portion 22b (inner connecting portion) connecting the radially inner ends of two adjacent core portions 22a, but also a connecting portion 22c (outer connecting portion) connecting the radially outer ends of two adjacent core portions 22a. However, from the viewpoint of motor output, it is preferable not to provide the outer connecting portion 22c, which has a high contribution rate to generating magnetic flux facing the stator 2. Therefore, the second core 22 of the outer core 20b of the rotor core 20 in the rotor 3 does not have a connecting portion located radially outside the magnet 30, but only has a connecting portion 22b located radially inside the magnet 30. This stabilizes the output of the motor 1.

[0097] In the rotor 3 according to this embodiment, each of the plurality of core portions 22a in the second core 22 of the outer core 20b of the rotor core 20 has a projection 22a1 that projects in the circumferential direction from the radially outer end portion.

[0098] With this configuration, when the magnet 30 is inserted into the magnet insertion hole 23 (through hole HL + gap GP) of the rotor core 20, the protrusion 22a1 is positioned radially outward of the magnet 30. This allows the protrusion 22a1 to function as a stopper that restricts radially outward movement of the magnet 30. This makes it possible to prevent the magnet 30 from falling out of the magnet insertion hole 23, even if the second core 22 does not have to be provided with a connecting portion 22c as shown in FIG.

[0099] In the rotor 3 according to this embodiment, each of the plurality of first cores 21 in the outer core 20b of the rotor core 20 has a projection 21a that projects in the circumferential direction from the radially outer end.

[0100] With this configuration, when the magnet 30 is inserted into the magnet insertion hole 23 (through hole HL + gap GP) of the rotor core 20, the protrusion 21a is positioned radially outward of the magnet 30. This allows the protrusion 21a to function as a stopper that restricts radially outward movement of the magnet 30. Therefore, even if the second core 22 does not have a connecting portion 22c as shown in Figure 10, it is possible to prevent the magnet 30 from falling out of the magnet insertion hole 23.

[0101] In the rotor 3 according to this embodiment, the outer core 20b has a plurality of communication holes 24, each of which communicates with one of the plurality of first cores 21 and one of the plurality of core portions 22a of the second core 22. The communication holes 24 are filled with resin 40.

[0102] With this configuration, the resin 40 filled in the communication holes 24 has an anchor effect, so that the outer core 20b and the resin 40 can be firmly fixed together.

[0103] Next, a method for manufacturing the rotor 3 configured as above will be described with reference to Fig. 11. Fig. 11 is a diagram for explaining the method for manufacturing the rotor 3 according to the embodiment. In Fig. 11, (a) shows the process of setting the outer core 20b in a mold, (b) shows the process of setting the inner core 20a in the mold, and (c) shows the process of setting the magnet 30 in the mold. The mold is omitted in Fig. 11. In Fig. 11, the diagram on the left is a perspective view, and the diagram on the right is a top view.

[0104] First, the rotor core 20 is set in a mold for injection molding. In this embodiment, the inner core 20a and the outer core 20b are set in the mold.

[0105] Specifically, as shown in FIG. 11(a), the outer core 20b, in which the first core 21 and the second core 22 are assembled in advance, is set in a mold.

[0106] 11(b), the inner core 20a is set in the mold. Specifically, the inner core 20a is placed inside the outer core 20b. At this time, the inner core 20a can be easily placed in a predetermined position in the mold by abutting a mold pin against a recess that is arc-shaped in a plan view and provided on the outer peripheral surface of the inner core 20a.

[0107] In this way, the rotor core 20 can be set in the mold by setting the outer core 20b and the inner core 20a in the mold. In this embodiment, the inner core 20a is set after the outer core 20b is set. However, this is not limited to this. Specifically, the outer core 20b may be set after the inner core 20a is set.

[0108] Next, as shown in Figure 11 (c) , a plurality of magnets 30 are inserted radially into the rotor core 20 set in the mold. Specifically, a magnet 30 is inserted into each of the plurality of magnet insertion holes 23 of the rotor core 20. In this embodiment, a plurality of magnetized magnets 30 are inserted into the rotor core 20. That is, the magnets 30 are magnetized in advance, and then the magnetized magnets 30 are inserted into the magnet insertion holes 23 of the rotor core 20. The magnet insertion holes 23 are defined by the gaps GP between two adjacent first cores 21 in the plurality of first cores 21 and the through holes HL of the second cores 22, and therefore each of the plurality of magnets 30 is inserted into the magnet insertion holes 23 defined by the gaps GP and the through holes HL.

[0109] FIG. 12 is a cross-sectional view showing the rotor core 20 and magnets 30 set in the mold 100. FIG. 13 is an enlarged cross-sectional view of the rotor core 20 and magnets 30 set in the mold 100. When the plurality of magnets 30 are inserted into the rotor core 20 in this manner, as shown in FIGS. 12 and 13 , the mold 100 is brought into contact with the radially outer surfaces 30 a of the plurality of magnets 30. Specifically, the top surfaces of the protrusions 110 provided on the mold 100 are brought into surface contact with the outer surfaces 30 a of the magnets 30. This allows the plurality of magnets 30 to be held in the mold 100. In this embodiment, when the plurality of magnets 30 are inserted into the rotor core 20, the circumferential side surfaces of the protrusions 21 a of the first core 21 are in contact with the mold 100. Specifically, the side surfaces of the protrusions 110 of the mold 100 are brought into contact with the entire circumferential side surfaces of the protrusions 21 a of the first core 21.

[0110] The shape of the top surface of the convex portion 110 of the mold 100 is a rectangle extending in the longitudinal direction of the magnet 30. The width of the top surface of the convex portion 110 of the mold 100 is constant. In this embodiment, as shown in FIGS. 12 and 13 , the convex portion 110 of the mold 100 is set so as to fit between the protrusion 21 a of one of two adjacent first cores 21 and the protrusion 21 a of the other first core 21. At this time, although not shown, the convex portion 110 of the mold 100 is set so as to fit between the protrusion 22 a 1 of one of two adjacent core portions 22 a of the second core 22 and the protrusion 22 a 1 of the other core portion 22 a. Therefore, the width of the top surface of the convex portion 110 of the mold 100 is the same as the width of the two adjacent protrusions 21 a and the width of the two adjacent protrusions 22 a 1. The width of two adjacent protrusions 21a and the width of two adjacent protrusions 22a1 are set to be tighter than the clearance between magnet 30 and first core 21 (or core portion 22a of second core 22).

[0111] The mold 100 is in contact not only with the outer surface 30a of the magnet 30 but also with the outer surface (outer peripheral surface) of the outer core 20b. Specifically, the mold 100 is in surface contact with the outer surface of the first core 21 in the outer core 20b, and is also in surface contact with the outer surface of the second core 22 in the outer core 20b. In this way, the mold 100 not only holds the multiple magnets 30, but also holds the outer core 20b of the rotor core 20.

[0112] Next, although not shown, after the magnets 30 are set inside the rotor core 20, resin 40 is injected into the mold 100 to mold the rotor core 20 and the plurality of magnets 30. This makes it possible to obtain a molded product in which the rotor core 20 and the plurality of magnets 30 are integrally molded with the resin 40. Specifically, the inner core 20a, the outer core 20b, and the plurality of magnets 30 are integrally molded with the resin 40.

[0113] At this time, the mold 100 is in contact with the radially outer surface 30a of the magnet 30. Therefore, when the molded product is removed from the mold 100, the outer surface 30a of the magnet 30 is not covered with the resin 40 and is exposed. Thereafter, the rotor 3 can be obtained by fixing the rotating shaft 10 to the molded product in which the rotor core 20 and the multiple magnets 30 are integrally molded with the resin 40.

[0114] As described above, in the manufacturing method of the rotor 3 according to this embodiment, in the process of inserting the plurality of magnets 30 into the rotor core 20, the die 100 is brought into contact with the radial outer surfaces 30a of the plurality of magnets 30.

[0115] As a result, the multiple magnets 30 arranged radially inside the rotor core 20 are held by the mold 100. In other words, the multiple magnets 30 are fixed in predetermined positions in the mold 100 so that they do not move. Therefore, injection molding can be performed with the multiple magnets 30 fixed in place, and the rotor core 20 and the multiple magnets 30 can be fixed with the resin 40. This makes it possible to obtain a rotor 3 in which the multiple magnets 30 are precisely arranged in predetermined positions. Furthermore, by combining this rotor 3 with the stator 2, it is possible to obtain a motor 1 in which cogging torque and torque ripple caused by misalignment of the magnets 30 are suppressed.

[0116] In particular, in this embodiment, the rotor core 20 is also held by the mold 100. This makes it possible to prevent the rotor core 20 from moving when the magnets 30 are inserted into the rotor core 20. Therefore, injection molding can be performed in a fixed state, with not only the plurality of magnets 30 but also the rotor core 20, and the rotor core 20 and the plurality of magnets 30 fixed together with the resin 40. This makes it possible to obtain a rotor 3 in which the plurality of magnets 30 and the rotor core 20 are precisely arranged in predetermined positions.

[0117] Furthermore, by precisely arranging the multiple magnets 30 in predetermined positions, the precision of the inter-pole pitch between the north and south poles of the multiple magnets 30 is improved. Therefore, when position control is performed using the magnetic force of the magnets 30 using, for example, a Hall sensor, there is no variation in the timing of energization. This allows for accurate position control of the motor 1. For example, it is possible to prevent deterioration of controllability, resulting in unstable rotation speed, and increased or variable noise or vibration.

[0118] Furthermore, in the rotor 3 according to this embodiment, as described above, the rotor core 20 is composed of an inner core 20a and an outer core 20b. The outer core 20b has a plurality of first cores 21 (split cores) that are circumferentially separated and arranged in an annular shape, and a pair of second cores 22 that sandwich the plurality of first cores 21 from the direction of the axis C of the rotating shaft 10. The second core 22 has a plurality of core portions 22a and a connecting portion 22b that connects two adjacent core portions 22a among the plurality of core portions 22a. The connecting portion 22b connects the two adjacent core portions 22a at locations other than their radially outer ends. In the manufacturing method of the rotor 3 according to this embodiment, in the step of setting the rotor core 20 in the mold 100, the inner core 20a and the outer core 20b are set in the mold 100. In the process of inserting the plurality of magnets 30 into the rotor core 20, each of the plurality of magnets 30 is inserted into a gap GP between two adjacent first cores 21 among the plurality of first cores 21. In the process of injecting resin 40 into the mold 100 to mold the rotor core 20 and the plurality of magnets 30, the inner core 20 a, the outer core 20 b, and the plurality of magnets 30 are integrally molded with the resin 40.

[0119] When the multiple core portions 22a of the second core 22 are connected by the connecting portions 22b in this way, the boundary portions between the connecting portions 22b and the core portions 22a are weak in strength. Therefore, when the magnet 30 is inserted into the gap GP between two adjacent core portions 22a during assembly to the outer core 20b, stress is applied to the boundary portions between the connecting portions 22b and the core portions 22a, and this boundary portion may act as a fulcrum, causing deformation and movement of the core portions 22a. In other words, there is a risk that a portion of the second core 22 in the outer core 20b may be deformed. As a result, the core portions 22a may be displaced from their predetermined positions, and the magnet 30 inserted into the gap GP between the core portions 22a may also be displaced from its predetermined position.

[0120] In contrast, in the manufacturing method of the rotor 3 in this embodiment, as described above, when the rotor core 20 and the plurality of magnets 30 are injection molded with resin 40, the plurality of magnets 30 and the second core 22 are held by the mold 100. This prevents the core portion 22a of the second core 22 from deforming and moving when the magnet 30 is assembled to the outer core 20b, even if the second core 22 has the connecting portion 22b. Therefore, it is possible to obtain a rotor 3 in which the plurality of magnets 30 and the rotor core 20 are precisely arranged in predetermined positions.

[0121] Furthermore, in the manufacturing method of the rotor 3 in this embodiment, in the step of inserting the plurality of magnets 30 into the rotor core 20 , the plurality of magnetized magnets 30 are inserted into the rotor core 20 .

[0122] As described above, when the multiple core portions 22a of the second core 22 are connected by the connecting portions 22b, the boundary portions between the connecting portions 22b and the core portions 22a are weak. Therefore, in a spoke-type IPM motor, the multiple magnets 30 are arranged with their main surfaces facing each other, and the repulsive force due to magnetic force is large. Therefore, when a pre-magnetized magnet 30 is inserted into the gap GP between two adjacent core portions 22a, stress is applied to the boundary portions between the connecting portions 22b and the core portions 22a, and the core portions 22a may deform and move with this boundary portion as a fulcrum.

[0123] In contrast, in the manufacturing method of the rotor 3 in this embodiment, as described above, when the rotor core 20 and the plurality of magnets 30 are injection molded with resin 40, the plurality of magnets 30 and the second core 22 are held by the mold 100. This makes it possible to prevent the core portion 22a of the second core 22 from deforming and moving even when the magnetized plurality of magnets 30 are inserted into the rotor core 20. Therefore, it is possible to obtain a rotor 3 in which the plurality of magnets 30 and the rotor core 20 are accurately arranged in predetermined positions.

[0124] Furthermore, the magnetized magnets 30 are inserted into the rotor core 20, and then the rotor core 20 and the multiple magnets 30 are fixed together with resin 40 by injection molding to form a single component. This improves production tact time compared to when magnets are magnetized after pre-magnetized magnets are inserted into the rotor core 20 and fixed together with resin 40 to form a single component. Furthermore, because an inverse magnetic field (demagnetizing magnetic field) is not applied to magnets that are not to be magnetized, a decrease in motor performance can be prevented.

[0125] Furthermore, in this embodiment, in order to prevent the radially outer surface 30a of the magnet 30 from being covered with the resin 40, when manufacturing the rotor 3, the top surfaces of the convex portions 110 of the mold 100 are brought into contact with the radially outer surface 30a of the magnet 30 in the process of inserting the multiple magnets 30 into the rotor core 20. However, as a result, the convex portions 110 of the mold 100 may push the magnet 30 radially inward, which may cause the magnet 30 to lose contact with the protrusions 21a of the first core 21 and the protrusions of the core portion 22a of the second core 22. In other words, gaps may be generated between the magnet 30 and the protrusions 21a of the first core 21 and the protrusions of the core portion 22a of the second core 22, causing the magnet 30 to be displaced from its predetermined position.

[0126] 14 is a cross-sectional view showing the rotor core 20 and magnets 30 set in a mold in a manufacturing method of a rotor 3 according to a modified example. As shown in FIG. 14 , in the process of inserting the multiple magnets 30 into the rotor core 20, it is preferable to prevent the mold 100 from contacting the radially outer surface 30a of the magnets 30. Specifically, it is preferable to position the mold 100A so that the top surfaces of the protrusions 110A provided on the mold 100A do not contact the outer surface 30a of the magnets 30, and a gap exists between the top surfaces of the protrusions 110A of the mold 100A and the outer surface 30a of the magnets 30. This allows the magnets 30 to easily contact the protrusions 21a of the first core 21 and the protrusions of the core portions 22a of the second core 22.

[0127] In this case, in order to stabilize the position of the first core 21, it is preferable to bring the side surfaces of the convex portions 110A of the mold 100A into contact with the circumferential side surfaces of the protrusions 21a of the first core 21. In this modification, as shown in Fig. 14, the side surfaces of the convex portions 110A of the mold 100A are not brought into contact with the entire circumferential side surfaces of the protrusions 21a of the first core 21, but are brought into contact with only a portion (approximately the outer half) of the circumferential side surfaces of the protrusions 21a of the first core 21.

[0128] After the multiple magnets 30 are inserted into the rotor core 20, when resin is injected into the mold 100A to mold the rotor core 20 and the multiple magnets 30, in this modified example, as shown in FIG. 14 , there is a gap between the top surface of the protrusion 110A of the mold 100A and the outer surface 30a of the magnet 30, so the resin fills the gap between the top surface of the protrusion 110A of the mold 100A and the outer surface 30a of the magnet 30. FIG. 15 is a cross-sectional view of a rotor 3A according to the modified example. As shown in FIG. 15 , in the rotor 3A, the radial outer surface 30a of the magnet 30 is also covered with resin 40A. Specifically, the entire radial outer surface 30a of each of the multiple magnets 30 is covered with resin 40A.

[0129] (Other Modifications) The rotor 3 and the motor 1 according to the present disclosure have been described above based on the embodiments, but the present disclosure is not limited to the above-described embodiments.

[0130] For example, in the above embodiment, the magnet 30 inserted into the rotor core 20 has a rectangular shape in top view. However, this is not limited to this. For example, the shape of the magnet 30 in top view may be trapezoidal or barrel-shaped.

[0131] In the above embodiment, the winding 2b of the stator 2 is wound around the stator core 2a in a concentrated winding manner. However, this is not limiting. For example, the winding 2b of the stator 2 may be wound around the stator core 2a in a distributed winding manner.

[0132] In the above embodiment, the motor 1 is a molded motor. However, this is not limiting. The technology of the present disclosure can be applied to motors other than molded motors. In other words, the technology of the present disclosure can be applied to motors in which the stator 2 is not covered with mold resin 8.

[0133] In the above embodiment, the motor 1 has been described as being applied to a fan motor in an air conditioner. However, the present invention is not limited to this. For example, the motor 1 in the above embodiment can be used in a variety of electrical appliances, including household appliances such as vacuum cleaners and refrigerators, and industrial appliances such as automotive appliances and robots.

[0134] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments that would occur to those skilled in the art, or forms realized by arbitrarily combining the components and functions of the embodiments within the scope of the present disclosure. The present disclosure also includes any combination of two or more claims from the multiple claims set forth in the claims at the time of filing, provided that there is no technical contradiction. For example, when a dependent claim set forth in the claims at the time of filing is made into a multiple claim or multiple multiple claims that cite all of the superordinate claims within the scope of the technical contradiction, the present disclosure also includes any combination of all claims included in that multiple claim or multiple multiple claims.

[0135] The electric motor according to the present disclosure can be widely used in devices equipped with an electric motor in various fields, including fan motors used in air conditioners and the like.

[0136] REFERENCE SIGNS LIST 1 Motor 2 Stator 2a Stator core 2b Winding 2c Insulator 3, 3A Rotor 4 First bearing 5 Second bearing 6 First bracket 7 Second bracket 8 Molded resin 9 Circuit board 10 Rotating shaft 20 Rotor core 20a Inner core 20a1 Through hole 20b Outer core 20bX Outer core 21 First core 21a Protrusion 22, 22X Second core 22a Core portion 22a1 Protrusion 22b, 22c Connecting portion 23 Magnet insertion hole 24 Communication hole 30 Magnet 30a Outer surface 40, 40A Resin 100, 100A Mold 110, 110A Protrusion GP Gap HL Through hole

Claims

1. A rotor comprising: a rotating shaft extending in the axial direction of an axis; a rotor core through which the rotating shaft is inserted; and a plurality of magnets arranged radially inside the rotor core around the rotating shaft, wherein the rotor core and the plurality of magnets are fixed with resin, and the radial outer surface of each of the plurality of magnets is not covered with the resin.

2. The rotor according to claim 1, wherein the rotor core has an inner core through which the rotating shaft passes, and an outer core located radially outward of the inner core and holding the plurality of magnets, the inner core, the outer core, and the plurality of magnets being fixed by the resin, the outer core having a plurality of first cores arranged in an annular shape around the rotating shaft, and a pair of second cores sandwiching the plurality of first cores in the axial direction, each of the plurality of magnets being inserted into a gap between two adjacent first cores of the plurality of first cores, each of the pair of second cores having a plurality of core sections corresponding one-to-one to the plurality of first cores, and a plurality of connecting sections that sequentially connect the plurality of core sections in a circumferential direction around the rotating shaft, and each of the plurality of connecting sections connecting two adjacent core sections of the plurality of core sections at a location other than the radially outer ends thereof.

3. The rotor according to claim 2, wherein each of the plurality of connecting portions connects radially inner ends of two adjacent core portions.

4. The rotor according to claim 2, wherein each of the plurality of core portions has a protrusion that protrudes in the circumferential direction from the radially outer end portion.

5. A rotor according to any one of claims 2 to 4, wherein each of the plurality of first cores has a protrusion that protrudes in the circumferential direction from the radially outer end.

6. A rotor according to any one of claims 2 to 4, wherein the outer core has a plurality of communication holes respectively communicating with the plurality of first cores and the plurality of core portions of the second core, and the resin is filled into the plurality of communication holes.

7. A rotor comprising: a rotating shaft extending in the axial direction of an axis; a rotor core through which the rotating shaft is inserted; and a plurality of magnets arranged radially inside the rotor core around the rotating shaft, wherein the rotor core and the plurality of magnets are fixed with resin; the rotor core has a plurality of cores arranged in a ring shape around the rotating shaft, each of the plurality of cores having a protrusion protruding circumferentially from its radially outer end; and each of the plurality of magnets is inserted into a gap between two adjacent cores in the plurality of cores and is in contact with the protrusion.

8. The rotor according to claim 7, wherein the radially outer surface of each of the plurality of magnets is covered with the resin.

9. A motor comprising: a rotor according to any one of claims 1 to 4, 7 and 8; and a stator that generates a magnetic force acting on the rotor.

10. A method for manufacturing a rotor, comprising: a step of setting a rotor core in a mold; a step of inserting a plurality of magnets radially into the rotor core set in the mold; and a step of injecting resin into the mold to mold the rotor core and the plurality of magnets, wherein in the step of inserting the plurality of magnets into the rotor core, the mold is brought into contact with the radial outer surfaces of the plurality of magnets.

11. The rotor core has an inner core through which the rotating shaft passes, and an outer core located radially outward of the inner core and holding the plurality of magnets, the outer core having a plurality of first cores arranged in an annular shape around the rotating shaft, and a pair of second cores sandwiching the plurality of first cores in the axial direction of the rotating shaft, each of the pair of second cores having a plurality of core portions corresponding one-to-one to the plurality of first cores, and a plurality of connecting portions sequentially connecting the plurality of core portions in a circumferential direction around the rotating shaft, each of the plurality of connecting portions connecting two adjacent core portions among the plurality of core portions at a location other than the radially outer ends, the step of setting the rotor core in the mold includes setting the inner core and the outer core in the mold, and the step of inserting the plurality of magnets into the rotor core includes inserting each of the plurality of magnets into a gap between two adjacent first cores among the plurality of first cores, 11. The rotor manufacturing method according to claim 10, wherein in the step of injecting resin into the mold to mold the rotor core and the plurality of magnets, the inner core, the outer core, and the plurality of magnets are integrally molded with the resin.

12. The method for manufacturing a rotor according to claim 11, wherein in the step of inserting the plurality of magnets into the rotor core, the plurality of magnetized magnets are inserted into the rotor core.

13. A method for manufacturing a rotor, comprising: a step of setting a rotor core in a mold; a step of inserting a plurality of magnets radially into the rotor core set in the mold; and a step of injecting resin into the mold to mold the rotor core and the plurality of magnets, wherein the rotor core has a plurality of cores arranged in a ring shape around the rotation axis, and each of the plurality of cores has a protrusion protruding circumferentially from an outer radial end, and in the step of inserting the plurality of magnets into the rotor core, each of the plurality of magnets is inserted into a gap between two adjacent cores in the plurality of cores, and the mold is brought into contact with the circumferential side of the protrusion of the core.

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