Rotor and electric motor

Abstract

To provide a rotor capable of reliably fixing the position of a permanent magnet to a rotor core without providing a member that covers an outer peripheral surface of the permanent magnet and an outside of a salient pole, and to provide an electric motor.SOLUTION: A rotor includes a rotor core 32 and a permanent magnet 33. The rotor core 32 includes a core body 32A and a plurality of salient poles 32B. In the rotor core 32, a magnet accommodation part is formed by the two salient poles 32B adjacent to each other and the outer peripheral surface of the core body 32A. The permanent magnet 33 is disposed in the magnet accommodation part on the outer periphery of the core body 32A. The rotor core 32 has a communication hole 70 communicating between the two magnet accommodation parts sandwiching the salient pole 32B therebetween and / or between an inner peripheral side space of the core body 32A and the magnet accommodation part. A bond magnet 75 is filled into the magnet accommodation part and the communication hole 70. A portion, of the bond magnet 75, filled into the magnet accommodation part constitutes the permanent magnet 33.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a rotor of an electric motor used for driving in-vehicle devices and the like, and an electric motor using the rotor.

Background Art

[0002] As an electric motor used for driving in-vehicle devices such as a wiper device, there is one in which a permanent magnet is provided on the rotor side. As an arrangement method of the permanent magnet of the rotor used in this type of electric motor, an arrangement in which the permanent magnet is arranged on the outer peripheral portion of the rotor core (SPM: Surface Permanent Magnet) is known.

[0003] As an electric motor adopting this method, the rotor core of the rotor includes a substantially cylindrical core body and a plurality of salient poles protruding in the radial direction from the outer peripheral portion of the core body, and permanent magnets are arranged between adjacent salient poles in the circumferential direction. In this electric motor, since the protruding direction of the salient poles of the rotor is directed outward in the radial direction, the magnetic flux linked by the coil of the stator easily flows into the salient poles. The salient poles generate reluctance torque that rotates the rotor core so as to reduce the magnetic resistance of the magnetic path of the linked magnetic flux when the electric motor is driven.

[0004] Further, as this type of electric motor, there is known one in which a rotor core and a plurality of permanent magnets are housed inside a non-magnetic substantially cylindrical magnet cover, and the outside of the rotor core and the plurality of permanent magnets is covered by the magnet cover (for example, see Patent Document 1).

[0005] In this electric motor, the outer circumference of the permanent magnets positioned between adjacent salient poles of the rotor core is pressed down by the peripheral wall of the magnet cover, thereby fixing the permanent magnets in place on the rotor core. On the other hand, the stator, located on the outer circumference of the rotor, is provided with multiple teeth that protrude radially inward, and coils are wound around each tooth. The tips of each tooth face the outer surface of the rotor with a minute gap in between. The magnetic flux linkage formed by each coil generates magnetic attraction and repulsion forces with respect to the magnetic flux formed by the permanent magnets on the rotor side, and also generates the aforementioned reluctance torque on the rotor. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 2015-511110 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the rotor used in the electric motor described in Patent Document 1 has a rotor core and multiple permanent magnets covered by a non-magnetic, relatively expensive magnetic cover, which tends to cause high product costs.

[0008] Furthermore, in the rotor used in the electric motor described in Patent Document 1, the outer surface of the permanent magnet and the outside of the tip of the salient pole are covered by a non-magnetic magnet cover, which increases the air gap between the inner surface of the stator (the tip surface of the teeth) and the permanent magnet or salient pole. In particular, in the case of an electric motor that uses the reluctance torque described above, if the distance between the inner surface of the stator and the tip of the salient pole becomes large, sufficient reluctance torque cannot be obtained.

[0009] Therefore, the present invention aims to provide a rotor and an electric motor that can reliably position and fix permanent magnets to a rotor core without providing a member to cover the outer surface of the permanent magnets and the outside of the salient poles. [Means for solving the problem]

[0010] To solve the above problems, the rotor according to the present invention employs the following configuration. That is, the rotor according to the first aspect of the present invention comprises a rotor core having a substantially annular core body and a plurality of salient poles projecting radially from the outer periphery of the core body, wherein a magnet housing portion is formed by two adjacent salient poles and the outer periphery of the core body, and a permanent magnet disposed in the magnet housing portion on the outer periphery of the core body, wherein the rotor core has a communication hole that connects at least one of the space between the two magnet housing portions with the salient poles in between, and the space between the inner periphery of the core body and the magnet housing portion, and the magnet housing portion and the communication hole are filled with bonded magnets, and the permanent magnet is composed of said bonded magnets.

[0011] With the above configuration, the solidified bonded magnets form magnetic blocks in each magnet housing and the inner circumferential space of the core body, and these magnetic blocks are interconnected by the magnetic blocks in the communication holes. As a result, the permanent magnets placed in the magnet housing of the rotor core are securely fixed in position on the rotor core without the need for any members to cover the outer surface of the permanent magnets and the outside of the salient poles.

[0012] A rotor according to a second aspect of the present invention, in the rotor according to the first aspect, has a communication hole that connects the two magnet housings, which sandwich the salient pole between them, with the inner circumferential space of the core body.

[0013] In this case, the bonded magnets solidified within the communication holes connect the magnet blocks in adjacent magnet housings, and simultaneously connect these magnet blocks to the magnet blocks in the inner circumferential space of the core body. Therefore, by adopting this configuration, the permanent magnets placed in the magnet housings of the rotor core can be more stably fixed to the rotor core.

[0014] A rotor according to a third aspect of the present invention is provided in the rotor according to the second aspect, wherein a slip-restricting groove extending along the axial direction of the core body is provided on the inner circumferential surface of the core body at the position where the communication hole opens.

[0015] In this case, when the molten bonded magnet solidifies within the escape-restricting groove, the resulting magnet block reliably restricts the radially outward displacement of the magnet block within the magnet housing, as well as positional displacement in the circumferential, radial, and axial directions.

[0016] A rotor according to a fourth aspect of the present invention is a rotor according to a third aspect, wherein the slip-restricting groove is arranged in a region that extends radially inward from each salient pole.

[0017] In this case, the magnet block solidified within the slip-restriction groove effectively functions as a magnetic path for the magnetic flux flowing between adjacent magnet blocks in the magnet housing section, separated by salient poles. Therefore, adopting this configuration makes it possible to improve motor characteristics.

[0018] A fifth aspect of the present invention is a rotor in which, in the rotor of the first to fourth aspects, the rotor core is constructed by stacking a plurality of core plates in the axial direction, and the core plate comprises a first core plate formed integrally over its entire area and a second core plate consisting of a plurality of plate pieces with separation gaps between the plurality of plate pieces, and the communication hole is formed by the separation gap surrounded by the first core plate and the second core plate.

[0019] In this case, when the first core plate and the second core plate are stacked in the axial direction, the separation gaps between the multiple plate pieces of the second core plate, together with the first core plate, form a communication hole. In this state, bond magnets are filled into each magnet housing and separation gap, and when the bond magnets solidify, the magnet blocks in the magnet housings are connected to the magnet blocks in other parts through the magnet blocks in the separation gaps. Therefore, when this configuration is adopted, by forming a structure in which a plurality of core plates are stacked in the axial direction, it becomes possible to improve the magnetic properties of the rotor core and to easily form communication holes in the rotor core.

[0020] The rotor according to the sixth aspect of the present invention is the rotor according to the fifth aspect, wherein each of the core plates has a main body forming portion that forms the core body and a salient pole forming portion that forms the salient pole, and the separation gap of the second core plate is a gap that separates the main body forming portion in the circumferential direction and separates the salient pole forming portion from the main body forming portion.

[0021] In this case, by providing the separation gap in the second core plate as described above, two magnet accommodating portions sandwiching the salient pole and the inner peripheral side space of the core body communicate with each other. Therefore, when this configuration is adopted, it becomes possible to easily form a structure that allows two magnet accommodating portions sandwiching the salient pole and the inner peripheral side space of the core body to communicate with each other.

[0022] The rotor according to the seventh aspect of the present invention is the rotor according to the sixth aspect, wherein the plurality of plate pieces include a plurality of substantially arc-shaped main body plate pieces that constitute the main body forming portion and a plurality of substantially rectangular salient pole plate pieces that constitute the salient pole forming portion.

[0023] In this case, a plurality of main body plate pieces and salient pole plate pieces of the same shape are prepared respectively, and by arranging them in a predetermined shape, the second core plate can be constituted. Therefore, when this configuration is adopted, it becomes possible to efficiently produce the rotor core and to improve the productivity of the rotor.

[0024] Boss portions that are concavo-convexly fitted with the first core plate adjacent in the stacking direction or the second core plate may be provided on each of the plate pieces of the second core plate.

[0025] In this case, by fitting the boss portions of each plate piece of the second core plate into the concavo-convex portions of other core plates adjacent in the stacking direction, each plate piece can be easily positioned and fixed with respect to the other core plates.

[0026] Further, an electric motor according to one aspect of the present invention includes an annular stator that generates a rotating magnetic field, and a rotor that is disposed radially inside the stator and rotates by receiving the rotating magnetic field, wherein the rotor is a rotor according to any one of the first aspect to the eighth aspect.

Advantages of the Invention

[0027] In the rotor and the electric motor according to the present invention, the magnet accommodating portion and the communication hole of the rotor core are filled with bonded magnets, and the permanent magnets between the salient poles are constituted by the bonded magnets. When the rotor and the electric motor according to the present invention are adopted, the permanent magnets can be reliably positioned and fixed to the rotor core without providing a member for covering the outer peripheral surface of the permanent magnets and the outside of the salient poles.

Brief Description of the Drawings

[0028] [Figure 1] Perspective view of the electric motor of the embodiment. [Figure 2] Cross-sectional view taken along line II-II of FIG. 1. [Figure 3] Perspective view of the rotor of the embodiment. [Figure 4] Partial cross-sectional perspective view of the rotor of the embodiment sectioned at the IV-IV cross-section of FIG. 3. [Figure 5] Cross-sectional view taken along line V-V of FIG. 3. [Figure 6] Perspective view of the first core plate of the embodiment. [Figure 7] Perspective view of the second core plate of the embodiment. [Figure 8] Perspective view of the rotor core of the embodiment. [Figure 9] Perspective view of the rotor of another embodiment. [Figure 10] Plan view of the second core plate of Modification 1. [Figure 11] Plan view of the second core plate in modified example 2. [Figure 12] A plan view of the second core plate in modified example 3. [Modes for carrying out the invention]

[0029] Embodiments of the present invention will be described below with reference to the drawings. In each embodiment and modification described below, the same parts will be denoted by common reference numerals, and redundant descriptions will be omitted.

[0030] (Motor unit) Figure 1 is a perspective view of a motor unit 1 used in a vehicle. Figure 2 is a cross-sectional view of the motor unit 1 cut along the rotation axis of the electric motor 2. The motor unit 1 is used, for example, as a power source for a vehicle's wiper system. As shown in Figures 1 and 2, the motor unit 1 comprises an electric motor 2, a reduction unit 3 that reduces the rotation of the electric motor 2 and outputs the reduced speed, and a controller 4 that controls the drive of the electric motor 2. In this specification, with respect to the electric motor 2 and motor unit 1, "axial direction" means the direction along the rotation axis (axis C1) of the rotation shaft 31 of the electric motor 2, and "circumferential direction" means the circumferential direction centered on the rotation axis (axis C1) of the rotation shaft 31. Furthermore, "radial direction" means the radial direction centered on the rotation axis (axis C1) of the rotation shaft 31.

[0031] (Electric motor) The electric motor 2 comprises a motor case 5, a substantially cylindrical stator 8 housed within the motor case 5, and a rotor 9 positioned radially inward of the stator 8 and rotatably mounted relative to the stator 8. The electric motor 2 of this embodiment is a so-called brushless motor that does not require brushes to supply power to the stator 8.

[0032] (Motor case) The motor case 5 is made of a material with excellent heat dissipation properties, such as an aluminum alloy. The motor case 5 consists of a first motor case 6 and a second motor case 7, which are configured to be separable in the axial direction. The first motor case 6 and the second motor case 7 are each formed in a bottomed cylindrical shape. The first motor case 6 is integrally molded with the gear case 40 of the reduction unit 3 such that its bottom portion 10 is connected to the gear case 40. A through hole is formed approximately in the radial center of the bottom portion 10, through which the rotating shaft 31 of the electric motor 2 can be inserted.

[0033] Furthermore, outer flange portions 16 and 17 are formed at the openings 6a and 7a of the first motor case 6 and the second motor case 7, respectively, extending radially outward. The motor case 5 has an internal space formed by abutting the outer flange portions 16 and 17 together. The stator 8 and rotor 9 are arranged in the internal space of the motor case 5. The stator 8 is fixed to the inner circumferential surface of the motor case 5.

[0034] (Stator) The stator 8 comprises a stator core 20 made of laminated electromagnetic steel sheets or the like, and a plurality of coils 24 wound around the stator core 20. The stator core 20 has an annular core body portion 21 and a plurality of teeth 22 protruding radially inward from the inner circumference of the core body portion 21. The inner surface of the core body portion 21 and each tooth 22 are covered by a resin insulator 23. The coils 24 are wound around the corresponding predetermined teeth 22 from above the insulator 23. Each coil 24 generates a magnetic field (rotating magnetic field) for rotating the rotor 9 by power supplied through the controller 4.

[0035] The rotor 9 is rotatably positioned radially inward of the stator 8 with a small gap between them. The rotor 9 is positioned radially inward of the stator 8 and rotates in response to the rotational magnetic field generated by the coils 24 of the stator 8. The rotor 9 comprises a substantially cylindrical rotor core 32 in which a rotating shaft 31 is press-fitted and fixed to the inner circumference, and permanent magnets 33 positioned on the outer circumference of the rotor core 32. In this embodiment, the rotating shaft 31 is formed integrally with the worm shaft 44 that constitutes the reduction gear 3. The rotating shaft 31 and the worm shaft 44 are rotatably supported by the motor case 5 and the gear case 40. The rotating shaft 31 and the worm shaft 44 rotate around the axis of rotation (axis center C1). The detailed structure of the rotor 9 will be described later.

[0036] (Deceleration part) The reduction unit 3 comprises a gear case 40 integrated with the motor case 5, and a worm reduction mechanism 41 housed within the gear case 40. The gear case 40 is made of a metal material with excellent heat dissipation properties, such as an aluminum alloy. The gear case 40 is formed in a box shape with an opening 40a on one side. The gear case 40 has a gear housing section 42 that houses the worm reduction mechanism 41 inside. In addition, an opening 43 is formed in the side wall 40b of the gear case 40 where the first motor case 6 is integrally formed, connecting the through hole of the first motor case 6 to the gear housing section 42.

[0037] A roughly cylindrical bearing boss 49 is provided protruding from the upper wall 40c of the gear case 40. The bearing boss 49 is for rotatably supporting the output shaft 48 of the worm reduction mechanism 41, and a sliding bearing (not shown) is arranged on its inner circumference. An O-ring (not shown) is fitted to the inside of the tip of the bearing boss 49. In addition, multiple ribs 52 are provided protruding from the outer circumference of the bearing boss 49 to ensure rigidity.

[0038] The worm reduction mechanism 41 housed in the gear housing 42 consists of a worm shaft 44 and a worm wheel 45 that meshes with the worm shaft 44. The worm shaft 44 is rotatably supported at both axial ends by the gear case 40 via bearings 46 and 47. An output shaft 48 is coaxially and integrally provided on the worm wheel 45. The rotation axes of the worm wheel 45 and the output shaft 48 are arranged so as to be approximately perpendicular to the rotation axis (axis center C1) of the worm shaft 44 (rotation axis 31 of the electric motor 2). The output shaft 48 protrudes outward from the bearing boss 49 of the gear case 40. A spline 48a is formed at the protruding tip of the output shaft 48, which can be connected to an object to be motor-driven.

[0039] Furthermore, the worm wheel 45 is equipped with a sensor magnet (not shown). The position of this sensor magnet is detected by a magnetic detection element 50 provided in the controller 4, which will be described later. In other words, the rotational position of the worm wheel 45 is detected by the magnetic detection element 50 of the controller 4.

[0040] (controller) The controller 4 has a controller board 51 on which a magnetic detection element 50 is mounted. The controller board 51 is positioned within an opening 40a of the gear case 40 such that the magnetic detection element 50 faces the sensor magnet of the worm wheel 45. The opening 40a of the gear case 40 is closed by a cover 53.

[0041] The controller board 51 is connected to the terminals of multiple coils 24 drawn from the stator core 20. The controller board 51 is also electrically connected to the terminals of the connector 11 (see Figure 1) provided on the cover 53. In addition to the magnetic detection element 50, the controller board 51 is also equipped with a power module (not shown) consisting of switching elements such as FETs (Field Effect Transistors) that control the drive voltage supplied to the coils 24, and capacitors (not shown) that smooth the voltage.

[0042] (Detailed rotor structure) Figure 3 is a perspective view of the rotor 9 of this embodiment, and Figure 4 is a partial cross-sectional perspective view of the rotor 9. The cross-section shown in Figure 4 corresponds to the IV-IV cross-section of the rotor 9 in Figure 3. Figure 5 is a cross-sectional view of the rotor 9 along the VV line in Figure 3. The rotor 9 comprises a rotor core 32 made of a magnetic material and permanent magnets 33 arranged on the outer circumference of the rotor core 32.

[0043] The rotor core 32 comprises a substantially cylindrical core body 32A and four salient poles 32B projecting radially from the outer circumference of the core body 32A. The rotor core 32 forms a magnet housing portion 59 with a substantially fan shape in plan view, formed by two adjacent salient poles 32B in the circumferential direction and the outer surface of the core body 32A. In this embodiment, a total of four magnet housing portions 59 are formed on the outer circumference of the core body 32A. A permanent magnet 33 is arranged in each magnet housing portion 59. Furthermore, a slip-restriction groove 58 is formed in the radially inward extension region of each salient pole 32B on the inner peripheral edge of the core body 32A. The slip-restriction groove 58 is formed in a plan view shape that is curved so that its bottom is convex radially outward, and this plan view shape extends along the axial direction of the core body 32A.

[0044] The rotor core 32 is constructed by stacking multiple core plates 60 made of a magnetic material such as electrical steel sheet in the axial direction. The core plates 60 are composed of a first core plate 61 and a second core plate 62, which have different structures, as will be described in detail later. An axial hole 34 is formed in the inner circumference of the core body 32A, into which the rotating shaft 31 (see Figure 2) is fixed by press-fitting. The inner surface of the axial hole 34 is divided at multiple points (four points) in the circumferential direction by the aforementioned slip-restriction grooves 58. Because the axial hole 34 is divided at multiple points on its inner surface by the slip-restriction grooves 58, the press-fitting resistance is reduced when the rotating shaft 31 is press-fitted into the inner circumference. Furthermore, the four salient poles 32B of the rotor core 32 protrude radially from the outer circumference of the core body 32A at equal intervals, and their protruding portions extend along the axial direction.

[0045] Figure 6 is a perspective view of the first core plate 61, and Figure 7 is a perspective view of the second core plate 62. The first core plate 61 is composed entirely of a single plate material, while the second core plate 62 is composed of multiple plate pieces. As shown in Figure 6, the first core plate 61 has an annular body forming portion 61a that constitutes the core body 32A of the rotor core 32, and salient pole forming portions 61b that constitute each salient pole 32B of the rotor core 32. The multiple salient pole forming portions 61b of the first core plate 61 extend radially from the outer circumference of the body forming portion 61a. In addition, groove forming portions 61c that form the aforementioned slip-restricting groove 58 are formed on the inner peripheral edge of the body forming portion 61a. The groove forming portion 61c has an arc-shaped groove at its bottom, and when multiple first core plates 61 are stacked in the axial direction, a continuous slip-restricting groove 58 is formed in the axial direction.

[0046] Furthermore, a U-shaped groove 67 is formed on the end face in the extending direction of each salient pole forming portion 61b, recessed inward in the radial direction. This U-shaped groove 67 is designed to make the stator 8 less susceptible to the effects of sudden changes in the magnetic force on the rotor 9 side when the salient pole 32B crosses the gap between adjacent teeth 22 (see Figure 2) on the stator 8 side during the rotation of the rotor 9. This suppresses the generation of torque ripple.

[0047] As shown in Figure 7, the second core plate 62 has four main plate pieces 63 that are substantially fan-shaped (arc-shaped) in plan view and constitute the core body 32A of the rotor core 32, and four salient pole plate pieces 64 that are substantially rectangular in plan view and constitute the salient poles 32B of the rotor core 32. The main plate pieces 63 constitute the main body forming portion 62a of the second core plate 62. The salient pole plate pieces 64 constitute the salient pole forming portion 62b of the second core plate 62.

[0048] The four main body plate pieces 63 are arranged to axially align with the annular main body forming portion 61a of the first core plate 61, and as shown in Figures 5 and 7, a separation gap 65a is secured between two adjacent main body plate pieces 63 in the circumferential direction. The separation gap 65a penetrates a portion of the core body 32A radially with a constant circumferential width.

[0049] The four salient pole plate pieces 64 are arranged to axially align with the salient pole forming portion 61b of the first core plate 61, and as shown in Figures 5 and 7, a separation gap 65b is secured radially outside the separation gap 65a between the main body plate pieces 63. The separation gap 65b penetrates a portion of the base side of the salient pole 32B in the circumferential direction with a constant radial width. The separation gap 65b connects two circumferentially adjacent magnet housing portions 59 to each other, and also connects the magnet housing portions 59 to the inner circumferential space 66 of the core body 32A via the separation gap 65a between the main body plate pieces 63 located radially inward. As described above, the interconnected separation gaps 65a and 65b are gaps that separate the main body forming portion 62a of the second core plate 62 in the circumferential direction, and separate the salient pole forming portion 62b of the second core plate 62 from the main body forming portion 62a.

[0050] A U-shaped groove 67 is formed on the extending end face (radially outer end face) of each salient pole plate piece 64, similar to the salient pole forming portion 61b of the first core plate 61. Also, as shown in Figure 7, each main body plate piece 63 and salient pole plate piece 64 has a boss portion 68 that protrudes to one side in the axial direction. Furthermore, as shown in Figure 6, a similar boss portion 68 is formed on the second core plate 62 of the first core plate 61 at a position corresponding to the above-mentioned boss portions 68. The boss portions 68 are formed in a bottomed cylindrical shape by press molding or the like so as to bulge out on one side in the axial direction of each core plate 60 (61, 62). These core plates 60 (61, 62), which are stacked in the axial direction, are fixed in a position by fitting the convex side of the boss portion 68 of the upper core plate 60 (61, 62) to the concave side of the boss portion 68 of the lower core plate 60 (61, 62).

[0051] Since the second core plate 62 has boss portions 68 formed on each main plate piece 63 and salient pole plate piece 64, the boss portions 68 can be fitted into the upper and lower boss portions 68, thereby fixing each plate piece 63, 64 in a positioned state. Furthermore, the first core plate 61, located at the lowest layer, has a through hole 68a (see Figure 4) instead of a boss portion 68.

[0052] Figure 8 is a perspective view of a rotor core 32 in which a first core plate 61 and a second core plate 62 are stacked in the axial direction. In this embodiment, the upper and lower regions of the rotor core 32 are constructed by stacking multiple first core plates 61, and the intermediate region is constructed by stacking multiple second core plates 62. Each second core plate 62 has a main body plate piece 63 and a salient pole plate piece 64 arranged such that separation gaps 65a and 65b are formed between each plate piece as described above. For this reason, a communication hole 70 is formed between the stacked block of multiple second core plates 62 and the upper and lower first core plates 61, connecting two magnet housing portions 59 that sandwich each salient pole 32B between them and the inner circumferential space 66 of the core body 32A. In this embodiment, four communication holes 70 are provided, the same number as the salient poles 32B. In addition, each communication hole 70 communicates with a release-restricting groove 58 that extends along the axial direction of the core body 32A on the inner circumferential side of the core body 32A.

[0053] As shown in Figure 8, bond magnets 75 are filled into each magnet housing portion 59, communication hole 70, and escape-restricting groove 58 of the rotor core 32, which is constructed by stacking a first core plate 61 and a second core plate 62. The bond magnets 75 are continuously filled into each of the above-mentioned parts, for example by injection molding, while the rotor core 32 is housed in a mold.

[0054] The bonded magnet 75 is filled into each magnet housing 59, communication hole 70, and escape-restricting groove 58 in a molten state. As shown in Figures 3 to 5, the bonded magnet 75 solidifies inside these areas, causing the magnet blocks B1 solidified in adjacent magnet housings 59 to be interconnected through the magnet blocks B2 in the communication holes 70, and the magnet blocks B3 solidified in the escape-restricting groove 58 to be connected to two magnet blocks B1 solidified in adjacent magnet housings 59 through the magnet blocks B2 in the communication holes 70. Furthermore, the magnet blocks B1 solidified in each magnet housing section 59 become permanent magnets 33 that generate magnetic attraction and repulsion forces with the flux linkage formed by the coil 24 (see Figure 2) on the stator 8 side.

[0055] (Effects of the embodiment) In this embodiment, the rotor 9 has bonded magnets 75 filled in the magnet housing portion 59 and the communication hole 70 of the rotor core 32, and these bonded magnets 75 constitute the permanent magnets 33 between the salient poles 32B. Therefore, when the bonded magnets 75 filled in the magnet housing portion 59 and the communication hole 70 solidify, the bonded magnets 75 become magnet blocks in the magnet housing portion 59 and the inner circumferential space 66 of the core body 32A, and each magnet block is interconnected by the magnet blocks in the communication hole 70. Consequently, when the rotor 9 and electric motor 2 of this embodiment are used, the permanent magnets 33 can be reliably positioned and fixed to the rotor core 32 without providing a member to cover the outer circumferential surface of the permanent magnets 33 and the outside of the salient poles 32B.

[0056] Furthermore, the rotor 9 and electric motor 2 of this embodiment can eliminate the members covering the outer surface of the permanent magnet 33 and the outside of the salient pole 32B, as described above. Therefore, by adopting the rotor 9 and electric motor 2 of this embodiment, it becomes possible to contribute to United Nations-led Sustainable Development Goals (SDGs) Goal 7, "Ensure access to affordable, reliable, sustainable, and modern energy for all," and Goal 9, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0057] Furthermore, in this embodiment, the rotor 9 has a communication hole 70 formed in the rotor core 32 that connects two magnet housings 59, which sandwich the salient pole 32B between them, with the inner circumferential space 66 of the core body 32A. As a result, the bonded magnet 75 solidified within the communication hole 70 connects the magnet blocks in adjacent magnet housings 59, and at the same time connects these magnet blocks with the magnet blocks in the inner circumferential space 66 of the core body 32A. Therefore, by adopting this configuration, the permanent magnets 33 arranged in the magnet housing portion 59 of the rotor core 32 can be more stably positioned and fixed to the rotor core 32. However, in this embodiment, one communication hole 70 connects the two magnet housings 59 with the salient pole 32B in between to the inner circumferential space 66 of the core body 32A, but the configuration of the communication hole 70 is not limited to this. For example, the communication hole 70 may connect only the two magnet housings 59 with the salient pole 32B in between to each other, or it may connect each magnet housing 59 to the inner circumferential space 66 of the core body 32A.

[0058] Furthermore, in this embodiment, the rotor 9 is provided with a release-restricting groove 58 extending along the axial direction of the core body 32A at the position where the communication hole 70 opens on the inner circumferential surface of the core body 32A. Therefore, when the molten bonded magnet 75 solidifies within the release-restricting groove 58, the magnet block formed by solidification within the release-restricting groove 58 reliably restricts the radially outward displacement of the magnet block (permanent magnet 33) in the magnet housing 59, as well as positional displacement in the circumferential, radial, and axial directions. Therefore, by adopting this configuration, the permanent magnet 33 can be more stably positioned and fixed to the rotor core 32.

[0059] Furthermore, in this embodiment, the rotor 9 has the release-restricting groove 58 positioned in a region that extends radially inward from each salient pole 32B. As a result, the magnet blocks solidified within the release-restricting groove 58 effectively function as a magnetic path for the magnetic flux flowing between adjacent magnet blocks (permanent magnets 33) in the magnet housing section 59 across the salient pole 32B. Therefore, by adopting this configuration, magnetic flux can flow smoothly within the rotor core 32, making it possible to improve the motor characteristics of the electric motor 2.

[0060] Furthermore, in this embodiment, the rotor 9 is constructed by stacking a plurality of core plates 60 in the axial direction to form the rotor core 32. The core plates 60 include a first core plate 61 which is formed as a single unit throughout, and a second core plate 62 which consists of a plurality of plate pieces with separation gaps 65a and 65b between the plate pieces. The communication hole 70 is formed by the separation gaps 65a and 65b surrounded by the first core plate 61 and the second core plate 62. As a result, when bond magnets 75 are filled into each magnet housing portion 59 and the separation gaps 65a and 65b, and the bond magnets 75 solidify, the magnet blocks in the magnet housing portion 59 are connected to the magnet blocks in other portions through the magnet blocks in the separation gaps 65a and 65b. Therefore, by adopting this configuration, it becomes possible to improve the magnetic properties of the rotor core 32 by creating a structure in which multiple core plates 60 (first core plate 61 and second core plate 62) are stacked in the axial direction, and it also becomes possible to easily form communication holes 70 in the rotor core 32.

[0061] Furthermore, in this embodiment, the rotor 9 is provided with each core plate 60 having body forming portions 61a, 62a that form the core body 32A and salient pole forming portions 61b, 62b that form the salient poles 32B, and the separation gaps 65a, 65b of the second core plate 62 are gaps that separate the body forming portion 62a in the circumferential direction and separate the salient pole forming portion 62b from the body forming portion 62a. Therefore, by adopting this configuration, it becomes possible to easily form a structure (a structure having a communication hole 70) that connects the two magnet housings 59 with the salient pole 32B in between to the inner circumferential space 66 of the core body 32A.

[0062] Furthermore, in this embodiment, the rotor 9 comprises a second core plate 62 which includes a plurality of substantially arc-shaped main body plate pieces 63 constituting the main body forming portion 62a and a plurality of rectangular salient pole plate pieces 64 constituting the salient pole forming portion 62b. Therefore, the second core plate 62 can be constructed by preparing a plurality of main body plate pieces 63 and salient pole plate pieces 64 of the same shape and arranging them in a predetermined shape. Therefore, by adopting this configuration, it becomes possible to efficiently produce the rotor core 32 and increase the productivity of the rotor 9.

[0063] Furthermore, in this embodiment, the rotor 9 is provided with boss portions 68 on each body plate piece 63 and salient pole plate piece 64 of the second core plate 62 that interlock with the adjacent first core plate 61 or second core plate 62 in the stacking direction. Therefore, by interlocking the boss portions 68 of each body plate piece 63 and salient pole plate piece 64 with other core plates adjacent in the stacking direction, each plate piece 63, 64 can be easily fixed in position relative to other core plates. Therefore, when this configuration is adopted, the bond magnet 75 can be stably ejected with the rotor core 32 assembled.

[0064] Furthermore, in this embodiment, the rotor 9 has multiple second core plates 62 arranged together in the central axial region of the rotor core 32. As a result, the cross-sectional area of ​​the communication holes 70 formed by the separation gaps 65a and 65b of the multiple second core plates 62 becomes larger. Consequently, when filling the magnet housing 59 and the communication holes 70 with bonded magnets 75, the fluidity of the bonded magnets 75 is improved. Therefore, adopting this configuration will increase the productivity of the rotor 9.

[0065] <Other Embodiments> Figure 9 is a perspective view of the rotor 109 of this embodiment. The rotor 109 of this embodiment has a basic configuration that is almost the same as that of the above embodiment, but the way in which the first core plate 61 and the second core plate 62 are stacked differs from that of the above embodiment. The shapes of the first core plate 61 and the second core plate 62 are the same as those of the above embodiment.

[0066] In this embodiment, the rotor 109 has a first core plate 61 and a second core plate 62 of the rotor core arranged alternately along the axial direction. As a result, the communication holes 70 formed by the separation gaps 65a and 65b (see Figure 7) of the second core plate 62 are distributed over a wide area in the axial direction of the rotor core. Therefore, when the rotor 109 of this embodiment is adopted, the permanent magnet 33 can be firmly fixed to the rotor core, and the magnetic properties of the rotor core can be made substantially uniform throughout the entire axial range.

[0067] <Example 1> Figure 10 is a plan view of the second core plate 262 of this modified example. In this modified example, the second core plate 262 has a release-restricting groove 58 and a separation gap 265a formed between the ends of adjacent substantially fan-shaped (substantially arc-shaped) main plate pieces 63. The separation gap 265a communicates with the separation gap 265b between the main plate piece 63 and the salient pole plate piece 64, and is formed so that its width gradually decreases from the separation gap 265b toward the radially inward release-restricting groove 58. In this modified example as well, the same functionality as in the above embodiment can be obtained. Furthermore, the surface forming the separation gap 265a at the end of the main plate piece 63 may be formed by a curved surface. In this case, the fluidity of the bonded magnet is improved when filling the magnet housing portion and the communication hole with bonded magnet.

[0068] <Modification 2> Figure 11 is a plan view of the second core plate 362 of this modified example. In this modified example, the second core plate 362 has a substantially fan-shaped (substantially arc-shaped) main plate piece 63, and a projection 77 extending radially outward from the circumferential end of the main plate piece 63 to form the base of the salient pole. Furthermore, a release-restricting groove 58 and a separation gap 365a are formed between the ends (including the projection 77) of adjacent main plate pieces 63. The separation gap 365a communicates with the separation gap 365b between the projection 77 of an adjacent pair of main plate pieces 63 and the salient pole plate piece 64, and extends linearly from the separation gap 365b toward the radially inward release-restricting groove 58. In this modified example as well, the same function as in the above embodiment can be obtained.

[0069] <Variation 3> Figure 12 is a plan view of the second core plate 462 of this modified example. In this modified example, the second core plate 462 has projections 77 extending radially outward from the circumferential ends of the roughly fan-shaped (roughly arc-shaped) main plate pieces 63, similar to Modification 2, to form the base of the salient pole. Between the ends (including the projections 77) of adjacent main plate pieces 63, a release-restricting groove 58 and a separation gap 465a are formed. Between the projections 77 of an adjacent pair of main plate pieces 63 and the salient pole plate piece 64, a roughly L-shaped separation gap 465b is formed, with its center projecting radially inward. The top of the separation gap 465b communicates with the separation gap 465a between adjacent main plate pieces 63. In this modified example as well, the same functions as in the above embodiment can be obtained. In this modified example, the separation gap 465b is formed in a roughly L-shape with its center protruding radially inward, which improves the fluidity of the bonded magnet when filling the magnet housing and communication hole with the bonded magnet. Furthermore, in this modified example, the separation gap 465b is formed in a roughly L-shape, but the shape of the separation gap 465b may be other shapes such as a curved shape. In this case as well, if the separation gap 465b is made into a curved shape that bulges convexly inward in the radial direction, the fluidity of the bond magnet toward the communication hole can be improved.

[0070] It should be noted that the present invention is not limited to the embodiments described above, and various design modifications are possible without departing from the spirit of the invention. For example, in the above embodiment, the communication hole 70 communicates with the inner circumferential space 66 of the core body 32A at an extension position radially inward of the salient pole 32B. However, the opening position of the communication hole 70 on the inner circumferential side of the core body 32A does not necessarily have to be at an extension position radially inward of the salient pole 32B. The opening position of the communication hole 70 may be at a position shifted circumferentially from the extension position of the salient pole 32B.

[0071] Furthermore, in the above embodiment, a detachment-restricting groove 58 is formed on the inner circumferential surface of the core body 32A along the axial direction, but the detachment-restricting groove 58 is not necessarily required.

[0072] Furthermore, in the above embodiment, the rotor core 32 is composed of a plurality of core plates 60 stacked in the axial direction, but the rotor core 32 does not necessarily have to be composed of a plurality of core plates 60. The rotor core 32 may be composed of, for example, a single-piece block. [Explanation of Symbols]

[0073] 1…Motor unit, 2…Electric motor, 3…Reduction unit, 4…Controller, 5…Motor case, 6…First motor case, 6a…Opening, 7…Second motor case, 7a…Opening, 8…Stator, 9,109…Rotor, 10…Bottom, 11…Connector, 16,17…Outer flange, 20…Stator core, 21…Core body, 22…Teeth, 24…Coil, 31…Rotating shaft, 32…Rotor core, 32A…Core body, 32B…Salliative pole, 33…Permanent magnet, 34…Shaft hole, 40…, 40a…Opening, 40b…Side wall, 40c…Top wall, 41…Worm reduction mechanism, 42…Gear housing, 43…Opening, 44…Worm shaft, 45…Worm wheel, 46,47…Bearing, 48…Output shaft, 48a… Spline, 49...Bearing boss, 50...Magnetic detection element, 51...Controller board, 52...Rib, 53...Cover, 58...Removal restriction groove, 59...Magnet housing, 60...Core plate, 61...First core plate, 61a...Main body forming part, 61b...Sailing pole forming part, 61c...Groove forming part, 62, 262, 362, 462...Second core plate, 62a...Main body forming part, 62b...Sailing pole forming part, 63...Main plate piece, 64...Sailing pole plate piece, 65a, 65b...Separation gap, 66...Inner circumference space, 67...U-shaped groove, 68...Boss part, 68a...Through hole, 70...Communication hole, 75...Bonded magnet, 77...Protruding piece, 265a, 265b...Separation gap, 365a, 365b...Separation gap, 465a, 465b...Separation gap

Claims

1. A rotor core having a substantially annular core body and a plurality of salient poles projecting radially from the outer periphery of the core body, wherein a magnet housing portion is formed by two adjacent salient poles and the outer periphery of the core body, The core body comprises a permanent magnet disposed in the magnet housing portion on the outer circumference of the core body, The rotor core has a communication hole that connects at least one of the two magnet housings that sandwich the salient pole between them, and the inner circumferential space of the core body and the magnet housing, A rotor characterized in that the magnet housing portion and the communication hole are filled with bonded magnets, and the permanent magnet is composed of said bonded magnets.

2. The rotor according to claim 1, characterized in that the communication hole connects the two magnet housings with the salient pole in between and the inner circumferential space of the core body.

3. The rotor according to claim 2, characterized in that a slip-restricting groove extending along the axial direction of the core body is provided at the position where the communication hole opens on the inner circumferential surface of the core body.

4. The rotor according to claim 3, characterized in that the slip-restricting groove is located in a region that extends radially inward from each salient pole.

5. The rotor core is constructed by stacking multiple core plates in the axial direction. The aforementioned core plate is A first core plate formed as a single unit throughout, A second core plate comprising a plurality of plate pieces with separation gaps between the plurality of plate pieces, The rotor according to claim 1, characterized in that the communication hole is formed by the separation gap surrounded by the first core plate and the second core plate.

6. Each of the core plates has a body forming portion that forms the core body and a salient pole forming portion that forms the salient pole, The rotor according to claim 5, characterized in that the separation gap of the second core plate is a gap that separates the main body forming portion in the circumferential direction and separates the salient pole forming portion from the main body forming portion.

7. Multiple of the aforementioned plate pieces are The main body forming portion comprises a plurality of substantially arc-shaped main body plate pieces, The rotor according to claim 6, further comprising a plurality of substantially rectangular salient pole plate pieces constituting the salient pole forming portion.

8. The rotor according to claim 5, characterized in that each plate piece of the second core plate is provided with a boss portion that interlocks with an adjacent first core plate or second core plate in the stacking direction.

9. A ring-shaped stator that generates a rotating magnetic field, The stator comprises a rotor positioned radially inward and rotating in response to the rotating magnetic field, The rotor is characterized in that it is the rotor described in any one of claims 1 to 8.

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