Rotor and motor

Abstract

To provide a rotor that can reduce cogging torque while suppressing concentration of a pressing load from a magnet cover to permanent magnets, and a motor.SOLUTION: A rotor comprises a rotor core 32, permanent magnets 33, and a magnet cover 71. The rotor core 32 has a core main body part 32A and a plurality of salient poles 32B. The permanent magnets 33 are arranged between the salient poles 32B. The magnet cover 71 covers an outside of the rotor core 32 and the permanent magnets 33. The permanent magnets 33 each have, on both side areas in a circumferential direction of a magnet outside surface 33c facing an inner peripheral surface of the magnet cover 71, gradual space parts in which a clearance between an inner peripheral surface of a stator and the permanent magnet gradually increases from a center area in the circumferential direction to the outside. The magnet outside surface 33c and the magnet cover 71 are provided, between the two gradual space parts on the magnet outside surface 33c, with at least one non-contact part that is not in contact with both of them, and a plurality of contact parts that is in contact with both of them on both sides in the circumferential direction of the non-contact part.SELECTED DRAWING: Figure 6

Description

[Technical field]

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

[0002] Some motors used in vehicle wiper devices and the like have permanent magnets provided on the rotor side. A known arrangement of the permanent magnets on the rotor used in this type of motor is a surface permanent magnet (SPM) arrangement in which the permanent magnets are arranged on the outer periphery of the rotor core.

[0003] A rotor that adopts this method has a rotor core that has a roughly cylindrical core body and multiple salient poles that protrude radially from the outer periphery of the core body, with permanent magnets arranged between adjacent salient poles in the circumferential direction (a so-called inset type rotor). The salient poles of this type of rotor protrude radially outward, making it easier for the interlinkage magnetic flux from the stator coil to flow. The salient poles also generate reluctance torque, which rotates the rotor core to reduce the magnetic resistance (reluctance torque) of the magnetic path of the interlinkage magnetic flux.

[0004] Furthermore, as this type of rotor, a rotor core and a plurality of permanent magnets are housed inside a substantially cylindrical magnet cover, and the rotor core and the plurality of permanent magnets are covered by the magnet cover. In this rotor, the outer periphery of the permanent magnets arranged between the adjacent salient poles of the rotor core is pressed by the peripheral wall of the magnet cover, thereby fixing the permanent magnets to the rotor core. Meanwhile, the stator arranged on the outer periphery of the rotor is provided with a plurality of teeth protruding radially inward, and a coil is wound around each tooth. The tip of each tooth faces the outer periphery of the rotor with a small gap between them. The interlinkage magnetic flux formed by each coil generates magnetic attraction and repulsion forces between the magnetic flux formed by the permanent magnets on the rotor side, and generates the above-mentioned reluctance torque in the rotor.

[0005] Permanent magnets arranged between the salient poles of the rotor core suddenly change the magnetic flux density acting on the teeth when they pass over the tips of the teeth on the stator side during rotor rotation. This sudden change in magnetic flux density causes cogging torque when the rotor rotates. As a countermeasure, a rotor has been devised in which the outer shape of the permanent magnets is devised to suppress the sudden change in magnetic flux density when the rotor rotates (for example, see Patent Document 1).

[0006] The rotor described in Patent Document 1 has an outer arc surface (hereinafter referred to as "outer surface") of a permanent magnet arranged between the salient poles of a stator core, the outer arc surface having a radius of curvature smaller than the radius of curvature of an imaginary circle passing through the tips of the salient poles, and the circumferential center of the outer surface of the permanent magnet is set to be closest to the inner surface of the stator. The distance between the outer surface of the permanent magnet and the inner surface of the stator gradually increases from the circumferential center toward the outside. This makes the change in magnetic flux density acting on the teeth on the stator side during rotation of the rotor gentle, suppressing cogging torque. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2020-99121 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the rotor described in Patent Document 1, the circumferential center of the outer peripheral surface of the permanent magnet bulges outward in the radial direction of the rotor core compared to other parts of the outer peripheral surface. Therefore, when the permanent magnet is assembled into the cylindrical part of the magnet cover together with the stator core, the pressing load from the magnet cover is concentrated at the circumferential center of the outer peripheral surface of the permanent magnet, and there is a concern that the concentrated load may cause deterioration or damage to the permanent magnet.

[0009] SUMMARY OF THE PRESENT EMBODIMENTS The present invention is directed to providing a rotor and a motor capable of reducing cogging torque while suppressing the concentration of the pressing load from the magnet cover onto the permanent magnet. [Means for solving the problem]

[0010] In order to solve the above problems, the rotor according to the present invention employs the following configuration. In other words, the rotor of the present invention is a rotor rotatably arranged on the inner circumference of an annular stator, and comprises a rotor core having an approximately circular core body and a plurality of salient poles protruding radially from the outer circumference of the core body, permanent magnets arranged between adjacent salient poles in the circumferential direction of the rotor core, and a magnet cover covering the outside of the rotor core and the permanent magnets, wherein the permanent magnet has a gradual separation portion in both circumferential regions of the magnet outer surface facing the inner circumference of the magnet cover, in which the separation distance from the inner circumference of the stator gradually increases from the circumferential central region toward the outside, and the magnet outer surface and the magnet cover are provided with at least one non-abutment portion that does not abut against each other between the two gradual separation portions of the magnet outer surface, and a plurality of abutment portions that abut against each other on both circumferential sides of the non-abutment portion. Effect of the Invention

[0011] In the rotor according to the present invention, since the gradual separation portions are provided on both circumferential regions of the outer magnet surface of the permanent magnet, a sudden change in magnetic flux density is suppressed when the permanent magnet crosses the teeth on the stator side during rotation of the rotor. Furthermore, in the rotor according to the present invention, since the outer magnet surface of the permanent magnet and the magnet cover are provided with a plurality of abutting portions that abut against each other between the two gradual separation portions, the pressing load acting on the permanent magnet from the magnet cover is dispersed by the plurality of abutting portions. Therefore, when the rotor according to the present invention is used, it is possible to reduce the cogging torque while suppressing the concentration of the pressing load from the magnet cover to the permanent magnet. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a perspective view of a motor unit according to the embodiment. [Diagram 2] 2 is a cross-sectional view of the motor unit according to the embodiment taken along line II-II in FIG. [Diagram 3] FIG. 2 is a perspective view of a rotor according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 2 is an exploded perspective view of the rotor according to the embodiment. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is an enlarged view of part VII in FIG. [Figure 8] FIG. 8 is a cross-sectional view of another embodiment 1 corresponding to FIG. 7. [Figure 9] FIG. 8 is a cross-sectional view of another embodiment 2 corresponding to FIG. 7. [Figure 10] FIG. 8 is a cross-sectional view of another embodiment 3 corresponding to FIG. 7. [Figure 11] FIG. 8 is a cross-sectional view of another embodiment 4 corresponding to FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments described below, the same parts are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0014] (Motor unit) Fig. 1 is a perspective view of a motor unit 1 used in a vehicle. Fig. 2 is a cross-sectional view of the motor unit 1 taken along line II-II in Fig. 1. The motor unit 1 is used, for example, as a drive source for a wiper device of a vehicle. As shown in Figures 1 and 2, the motor unit 1 includes a motor 2, a speed reducer 3 that reduces the rotation speed of the motor 2 and outputs the reduced speed, and a controller 4 that controls the drive of the motor 2. In the following description, the term "axial direction" refers to the direction along the rotation axis of the rotating shaft 31 of the motor 2, and the term "circumferential direction" refers to the circumferential direction of the rotating shaft 31. Additionally, the term "radial direction" refers to the radial direction of the rotating shaft 31.

[0015] (Motor) The motor 2 includes a motor case 5, a substantially cylindrical stator 8 housed in the motor case 5, and a rotor 9 disposed radially inside the stator 8 and rotatable relative to the stator 8. The motor 2 of this embodiment is a so-called brushless motor that does not require brushes to supply power to the stator 8.

[0016] (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 is made up 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 cylindrical shape with a bottom. The first motor case 6 is molded integrally with the gear case 40 so that the bottom 10 is connected to the gear case 40 of the reduction unit 3. A through hole through which the rotating shaft 31 of the motor 2 can be inserted is formed in approximately the center in the radial direction of the bottom 10.

[0017] Further, outer flange portions 16, 17 that protrude radially outward are formed at the openings 6a, 7a of the first motor case 6 and the second motor case 7, respectively. In the motor case 5, the outer flange portions 16, 17 are butted against each other to form an internal space. A stator 8 and a rotor 9 are disposed in the internal space of the motor case 5. The stator 8 is fixed to the inner peripheral surface of the motor case 5.

[0018] (Stator) The stator 8 includes 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 includes an annular core body 21 and a plurality of (e.g., six) teeth 22 protruding radially inward from an inner periphery of the core body 21. The inner periphery of the core body 21 and each of the teeth 22 are covered with a resin insulator 23. The coils 24 are wound around corresponding predetermined teeth 22 from above the insulator 23. Each coil 24 generates a magnetic field for rotating the rotor 9 when power is supplied from the controller 4.

[0019] The rotor 9 is rotatably disposed on the radial inside of the stator 8 via a small gap. The rotor 9 includes a substantially cylindrical rotor core 32, into whose inner periphery the rotating shaft 31 is press-fitted, and four permanent magnets 33 (see Figs. 4 and 5) assembled to the outer periphery of the rotor core 32. In this embodiment, the rotating shaft 31 is integrally formed with a worm shaft 44 constituting the reduction unit 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 rotation axis (axis center C). For example, a ferrite magnet is used as the permanent magnet 33. However, the permanent magnet 33 is not limited thereto, and a neodymium sintered magnet or the like can also be used. The detailed structure of the rotor 9 will be described later.

[0020] (Deceleration part) The reduction unit 3 includes a gear case 40 integrated with the motor case 5, and a worm reduction mechanism 41 housed in 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 therein. In addition, an opening 43 that communicates with the through hole of the first motor case 6 and the gear housing section 42 is formed in the side wall 40b of the gear case 40 at a location where the first motor case 6 is integrally formed.

[0021] A generally cylindrical bearing boss 49 protrudes from the bottom wall 40c of the gear case 40. The bearing boss 49 rotatably supports the output shaft 48 of the worm reduction mechanism 41, and a plain bearing (not shown) is disposed on the inner periphery of the bearing boss 49. An O-ring (not shown) is attached to the inside of the tip of the bearing boss 49. In addition, a plurality of ribs 52 protrude from the outer periphery of the bearing boss 49 to ensure rigidity.

[0022] The worm reduction mechanism 41 housed in the gear housing 42 is composed of a worm shaft 44 and a worm wheel 45 meshed 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. The worm wheel 45 is coaxially and integrally provided with an output shaft 48 of the motor 2. The worm wheel 45 and the output shaft 48 are arranged such that their rotation axes are substantially perpendicular to the rotation axis (axis center C) of the worm shaft 44 (rotation shaft 31 of the motor 2). The output shaft 48 protrudes to the outside through a bearing boss 49 of the gear case 40. A spline 48a that can be connected to an object to be driven by the motor is formed at the protruding tip of the output shaft 48.

[0023] In addition, a sensor magnet (not shown) is provided on the worm wheel 45. The position of this sensor magnet is detected by a magnetic detection element 61 provided in the controller 4 (described later). In other words, the rotational position of the worm wheel 45 is detected by the magnetic detection element 61 of the controller 4.

[0024] (controller) The controller 4 has a controller board 62 on which a magnetic detection element 61 is mounted. The controller board 62 is disposed in the opening 40a of the gear case 40 so that the magnetic detection element 61 faces the sensor magnet of the worm wheel 45. The opening 40a of the gear case 40 is closed by a cover 63.

[0025] Terminal portions of the multiple coils 24 drawn out from the stator core 20 are connected to the controller board 62. In addition, a terminal of a connector 11 (see FIG. 1) provided on a cover 63 is electrically connected to the controller board 62. In addition to the magnetic detection element 61, the controller board 62 also has mounted thereon a power module (not shown) made up of switching elements such as FETs (Field Effect Transistors) that control the drive voltage supplied to the coils 24, a capacitor (not shown) that smoothes the voltage, and the like.

[0026] (Detailed structure of rotor) Fig. 3 is a perspective view of the rotor 9 of this embodiment, and Fig. 4 is a cross-sectional view of the rotor 9 taken along line IV-IV in Fig. 3. Fig. 5 is an exploded perspective view of the rotor 9, and Fig. 6 is a cross-sectional view of the rotor 9 taken along line VI-VI in Fig. 4. As shown in these figures, the rotor 9 comprises a rotor core 32 that can rotate around the rotation axis (axis center C) together with the rotation shaft 31 (see Figure 2), four permanent magnets 33 arranged on the outer periphery of the rotor core 32, a pair of load-receiving blocks 70 arranged respectively on one end and the other end in the axial direction of the rotor core 32, and a metal magnet cover 71 that covers the rotor core 32 and the permanent magnets 33 together with the pair of load-receiving blocks 70 from the outside in the axial and radial directions.

[0027] The rotor core 32 has a substantially cylindrical core body 32A and four salient poles 32B protruding in the radial direction from the outer circumferential surface of the core body 32A. The rotor core 32 is formed, for example, by stacking a plurality of electromagnetic steel plates in the axial direction. Note that the configuration of the rotor core 32 is not limited to this configuration. The rotor core 32 may be formed, for example, by pressure molding soft magnetic powder.

[0028] The arc surface on the outer periphery of the core main body portion 32A has an arc shape in which the arc center is eccentric radially outward with respect to the axis C (axis of rotation) of the rotor 9 and the radius of curvature is smaller than the curvature deformation of a virtual circle passing through the maximum radially outer bulge portion (the portion furthest radially outward from the axis C).

[0029] The four salient poles 32B radially protrude at equal intervals from the outer periphery of the core body 32A, and the protruding portions extend in the axial direction. The side surface of each salient pole 32B facing the circumferential direction of the rotor core 32 is formed by a flat surface. A permanent magnet 33 is disposed between each of the salient poles 32B adjacent to each other in the circumferential direction of the rotor core 32. Each salient pole 32B is formed so that the distance from the axis C (axis of rotation) of the rotor 9 to the radially outer end is substantially the same as the distance from the axis C (axis of rotation) of the rotor 9 to a maximum outer diameter portion 65 (see FIGS. 6 and 7) of the permanent magnet 33, which will be described later.

[0030] The inner peripheral surface of the core body 32A is formed with four arcuate surfaces centered on the axis C (axis of rotation) of the rotor 9, and escape grooves 73 extending radially outward from between adjacent arcuate surfaces. Each escape groove 73 extends radially outward by the same length, and the end in the extending direction is an arcuate engaging portion 73a. A locking claw 74 of a load-receiving block 70, which will be described later, is fitted into the engaging portion 73a of each escape groove 73. The rotating shaft 31 of the motor 2 is press-fitted and fixed into the four arcuate surfaces on the inner peripheral surface of the rotor core 32.

[0031] The permanent magnet 33 is formed in a generally arc shape when viewed in the axial direction. At both ends in the circumferential direction (arc direction) of the permanent magnet 33, there are provided a flat side end face 33a facing the flat side face of the salient pole 32B, and an inclined face 33b extending from the radially outer end of the side end face 33a at an angle in a direction away from the salient pole 32B. The permanent magnet 33 is formed such that when the permanent magnet 33 is assembled to the rotor core 32, the side end faces 33a and the inclined faces 33b on both sides in the circumferential direction are separated from the side faces of the salient pole 32B of the rotor core 32. A magnet outer surface 33c is provided on the radial outer side of the permanent magnet 33, connecting the radial outer ends of the inclined surfaces 33b on both circumferential sides. A magnet inner surface 33d is provided on the radial inner side of the permanent magnet 33, connecting the radial inner ends of the side end surfaces 33a on both circumferential sides. The detailed structures of the magnet outer surface 33c and magnet inner surface 33d of the permanent magnet 33 will be described later.

[0032] The axial length of each permanent magnet 33 is set to be longer than the axial length of the salient pole 32B of the rotor core 32. When assembled to the rotor core 32, each permanent magnet 33 is set to protrude from the salient pole 32B by approximately the same length on both ends in the axial direction.

[0033] 3 to 5, the magnet cover 71 has a cylindrical peripheral wall 71a and a pair of flange portions 71b, 71c that bend and extend radially inward from one end and the other end of the peripheral wall 71a, respectively. The rotor core 32 and the permanent magnets 33 are housed inside the peripheral wall 71a together with a pair of load receiving blocks 70. At least one of the pair of flange portions 71b, 71c is a crimped flange that is plastically deformed by crimping in a state in which the rotor core 32 and the permanent magnets 33 are disposed inside the peripheral wall 71a together with the pair of load receiving blocks 70. In this embodiment, one of the flange portions 71b is formed by bending radially inward in advance, and after the rotor core 32 and the permanent magnet 33 are housed inside the magnet cover 71 together with a pair of load-receiving blocks 70, the other flange portion 71c is crimped.

[0034] A pair of load receiving blocks 70 arranged on one and the other axial ends of the rotor core 32 have the same shape. The pair of load receiving blocks 70 are assembled to the rotor core 32 in an inverted state. The load-receiving block 70 has an annular portion 70A arranged to overlap the axial end face of the core body portion 32A of the rotor core 32, and four leg portions 70B that protrude radially from the outer circumferential surface of the annular portion 70A and are arranged to overlap the axial end faces of each salient pole 32B of the rotor core 32. The four leg portions 70B protrude at equal intervals on the outer periphery of the annular portion 70A. The load-receiving block 70 is formed, for example, from a hard resin. The load-receiving block 70 is formed in a shape that substantially overlaps with the rotor core 32 when viewed in the axial direction.

[0035] Locking claws 74 that protrude approximately along the axial direction toward the rotor core 32 are formed integrally with the inner peripheral edge of the annular portion 70A of the load receiving block 70 at positions extending radially inward from each leg portion 70B. The locking claws 74 are formed in an approximately semicircular cross section, and are fitted into escape grooves 73 (engagement portions 73a) on the inner circumference of the rotor core 32 when the load receiving block 70 is assembled to the end face of the rotor core 32. With each locking claw 74 fitting into the corresponding escape groove 73 (engagement portion 73a), the load receiving block 70 is restricted from relative displacement in the radial and circumferential directions with respect to the rotor core 32.

[0036] The pair of load receiving blocks 70 are assembled to one and the other axial end of the rotor core 32 having the permanent magnets 33 disposed between the salient poles 32B, and in this state are housed together with the rotor core 32 in a press-fit state within the peripheral wall 71a of the magnet cover 71. Then, the flange portion 71c at the end of the magnet cover 71 is crimped, so that the pair of load receiving blocks 70 are crimped and fixed to the magnet cover 71 together with the rotor core 32. At this time, the crimping load applied in the axial direction from the flange portion 71c is transmitted to the rotor core 32 via the load receiving blocks 70, and does not directly act on the permanent magnets. Therefore, deterioration and damage of the permanent magnets 33 due to the crimping of the flange portion 71c is suppressed.

[0037] (Detailed structure of permanent magnet) FIG. 7 is an enlarged view of part VII of the rotor 9 in FIG. 7, the magnet outer surface 33c of the permanent magnet 33 is provided with a flat surface 66 in a circumferential central region A1, and with arc surfaces 67 in outer regions A2 on both sides in the circumferential direction. The arc surfaces 67 of the outer regions A2 are formed in an arc shape such that, when the permanent magnet 33 is assembled to the rotor core 32, the arc center is eccentric radially outward with respect to the axis C (axis of rotation) of the rotor 9, and the radius of curvature is smaller than the radius of curvature of an imaginary circle passing through the tips of the four salient poles 32B of the rotor core 32. On the other hand, the inner peripheral surface (inner peripheral surface of the peripheral wall 71a) of the magnet cover 71 in which the permanent magnet is housed together with the rotor core 32 is formed in a perfect circular shape centered on the axis C (axis of rotation) of the rotor 9.

[0038] When the permanent magnet 33 is disposed between adjacent salient poles 32B of the rotor core 32, the boundary between the flat surface 66 of the central region A1 of the magnet outer surface 33c and each of the arc surfaces 67 of the outer region A2 is defined as a maximum outer diameter portion 65. The maximum outer diameter portion 65 is a portion where the length from the radial center position (axis center C) of the rotor core 32 is maximum. Therefore, when the permanent magnet 33 is pressed into the inner peripheral surface of the magnet cover 71 (the inner peripheral surface of the peripheral wall 71a) together with the rotor core 32, the two maximum outer diameter portions 65 of the magnet outer surface 33c come into contact with the inner peripheral surface of the magnet cover 71, and the flat surfaces 66 do not come into contact with the inner peripheral surface of the magnet cover 71. In this embodiment, the flat surface 66 and the opposing inner periphery of the magnet cover 71 form a non-contact portion, and each maximum outer diameter portion 65 and the opposing inner periphery of the magnet cover 71 form a contact portion. The flat surface 66 also forms a small outer diameter portion whose length from the center position in the radial direction of the rotor core 32 is shorter than that of the maximum outer diameter portion 65.

[0039] Furthermore, when the permanent magnet 33 is press-fitted together with the rotor core 32 into the inner circumferential surface of the magnet cover 71, the arcuate surface 67 of the outer region A2 of the magnet outer side surface 33c is spaced gradually from the maximum outer diameter portion 65 (the central region in the circumferential direction) toward the outside in the circumferential direction from the inner circumferential surface of the magnet cover 71. Therefore, when the rotor 9 is coaxially disposed on the inner circumferential portion of the stator 8 (see FIG. 2), the arcuate surfaces 67 of the magnet outer side surface 33c are also spaced gradually from the maximum outer diameter portion 65 (the central region in the circumferential direction) toward the outside in the circumferential direction from the inner circumferential surface of the stator 8. In this embodiment, the arc surface 67 of the outer region A2 of the magnet outer side surface 33c constitutes the gradual separation portion. The arc surface 67, whose separation distance from the inner peripheral surface of the stator 8 gradually increases outward in the circumferential direction, smooths the change in the magnetic flux density acting on the teeth 22 (see FIG. 2) on the stator 8 side when the rotor 9 rotates, thereby suppressing the cogging torque of the motor 2.

[0040] In addition, the magnet inner surface 33d of the permanent magnet 33 is configured as an arc surface having an inner diameter larger than the outer diameter of the outer peripheral surface of the core body portion 32A. In other words, the radius of curvature of the arc of the magnet inner surface 33d is set to be larger than the curvature deformation of the arc of the outer peripheral surface of the core body portion 32A, and the magnet inner surface 33d abuts on the outer peripheral surface of the core body portion 32A in the central region in the circumferential direction. Therefore, the pressing load input from the magnet cover 71 to the permanent magnet 33 is transmitted to the outer peripheral surface of the core body portion 32A through the central region in the circumferential direction of the magnet inner surface 33d.

[0041] (Effects of the embodiment) As described above, in the rotor 9 of this embodiment, the arc surfaces 67 are provided in the outer regions A2 on both circumferential sides of the magnet outer surface 33c of the permanent magnet 33 such that the separation distance from the inner circumferential surface of the stator 8 gradually increases from the central region A1 in the circumferential direction outward. Therefore, in the rotor 9 of this embodiment, it is possible to suppress a sudden change in magnetic flux density when the permanent magnet 33 crosses the teeth 22 on the stator 8 side during rotation of the rotor 9.

[0042] Furthermore, in the rotor 9 of this embodiment, a maximum outer diameter portion 65 that is an abutment portion with the magnet cover 71 is provided at the circumferentially inner position of the two arcuate surfaces 67 on the magnet outer surface 33c of the permanent magnet 33, and a small outer diameter portion (flat surface 66) is provided between the two maximum outer diameter portions 65. Therefore, in the rotor 9 of this embodiment, the pressing load from the magnet cover 71 can be distributed to multiple locations and transmitted to the permanent magnet 33. This makes it possible to suppress concentration of the pressing load from the magnet cover 71 and prevent deterioration and damage of the permanent magnet 33.

[0043] Therefore, when the rotor 9 of this embodiment is adopted, it is possible to reduce the concentration of the pressing load from the magnet cover 71 to the permanent magnets 33, while reducing the cogging torque. Therefore, by adopting the rotor 9 of this embodiment, it is possible to prevent deterioration and damage of the permanent magnets 33 and improve the performance of the motor 2 using the rotor 9. As a result, it is possible to contribute to Goal 7 of the Sustainable Development Goals (SDGs) led by the United Nations, which is to "Ensure access to affordable, reliable, sustainable and modern energy for all."

[0044] Furthermore, in the rotor 9 of this embodiment, a flat surface 66 is provided as a small outer diameter portion so as to linearly connect two maximum outer diameter portions 65 (circumferentially inner ends of the arc surfaces 67) of the magnet outer surface 33c when viewed in the axial direction. For this reason, when this configuration is adopted, two gradually separated portions (arc surfaces 67) and one small outer diameter portion (flat surface 66) can be formed on the magnet outer surface 33c with a simple configuration, and the maximum outer diameter portion 65 can be disposed at the boundary between each gradually separated portion (arc surface 67) and the small outer diameter portion (flat surface 66).

[0045] In addition, in the rotor 9 of this embodiment, the magnet inner surface 33d of the permanent magnet 33 is configured as an arc surface with an inner diameter larger than the outer diameter of the core body 32A, and the circumferential center region of the magnet inner surface 33d abuts on the outer circumferential surface of the core body 32A. Therefore, no air layer that hinders the flow of magnetic flux is formed between the circumferential center of the magnet inner surface 33d and the outer circumferential surface of the core body 32A. Therefore, when this configuration is adopted, the flow of magnetic flux between the center region of the magnet inner surface 33d and the core body becomes smooth, and the magnetic characteristics of the rotor 9 are improved.

[0046] (Another embodiment 1) FIG. 8 is a cross-sectional view of Alternative Embodiment 1 corresponding to FIG. 7 of the above embodiment. The rotor 109 of this embodiment differs from the above embodiment only in the shape of the magnet outer surface 133c of the permanent magnet 133. The magnet outer surface 133c has an arcuate surface 67 in the circumferential outer region A2 similar to that of the above embodiment. Meanwhile, the circumferential central region A1 is configured with an arcuate surface 68 that is convex radially outward and has a larger radius of curvature than the inner circumferential surface of the magnet cover 71. The boundary between each of the arcuate surfaces 67 on both sides in the circumferential direction and the central arcuate surface 68 is defined as a maximum outer diameter portion 65. In this embodiment, the central arcuate surface 68 constitutes the small outer diameter portion.

[0047] The rotor 109 of this embodiment has a basic configuration similar to that of the above embodiment, and therefore can provide the same basic effects as those of the above embodiment. However, in the rotor 109 of this embodiment, the arc surface 68 continues smoothly on the circumferential inside of the maximum outer diameter part 65, so that no edge part is formed near the maximum outer diameter part 65. Therefore, stress does not concentrate on the edge part when a pressing load is input from the magnet cover 71. Therefore, when this configuration is adopted, deterioration and damage of the permanent magnets 33 can be more effectively prevented. Furthermore, in the rotor 109 of this embodiment, the small outer diameter portion, the arc surface 68, is formed in the central region A1 so as to be continuous with the arc surface 67 of the magnet outer surface 33c, which is the gradually separated portion, so that the change in magnetic flux density that occurs when the permanent magnet 133 crosses the tip end of the teeth 22 (see FIG. 2) of the stator side 8 during rotation of the rotor 9 can be made more gradual. Therefore, when this configuration is adopted, the cogging torque can be further suppressed.

[0048] (Another embodiment 2) FIG. 9 is a cross-sectional view of Alternative Embodiment 2 corresponding to FIG. The rotor 209 of this embodiment differs from the above embodiment only in the shape of the magnet outer surface 233c of the permanent magnet 233. The magnet outer surface 233c has an arcuate surface 67 in the circumferential outer region A2, similar to the above embodiment. The circumferential central region A1 is configured with an arcuate surface 69 that is recessed radially inward. The boundary between each of the arcuate surfaces 67 on both sides in the circumferential direction and the central arcuate surface 69 is defined as a maximum outer diameter portion 65. In this embodiment, the central arcuate surface 69 constitutes the small outer diameter portion.

[0049] The rotor 209 of this embodiment has a basic configuration similar to that of the above embodiment, and therefore can provide the same basic effects as those of the above embodiment. However, in the rotor 209 of this embodiment, the small outer diameter portion of the magnet outer surface 233c is formed by the arc surface 69 recessed radially inward, so that, like the above embodiment, the permanent magnet 333 can be made even smaller and lighter while preventing deterioration and damage to the permanent magnet 233 caused by the pressing load from the magnet cover 71.

[0050] (Other embodiment 3) FIG. 10 is a cross-sectional view of Alternative Embodiment 3 corresponding to FIG. 7 of the above embodiment. The rotor 309 of this embodiment differs from the above embodiment only in the shape of the magnet inner side surface 333d of the permanent magnet 333. The magnet inner side surface 333d is formed in an arc shape with a smaller radius of curvature than the arc of the outer circumferential surface of the core body portion 32A of the rotor core 32. As a result, the magnet inner side surface 333d abuts against the outer circumferential surface of the core body portion 32A at two abutment portions 75 that are spaced apart in the circumferential direction. The two abutment portions 75 are disposed at symmetrical positions about the central position of the magnet inner side surface 333d in the circumferential direction.

[0051] The rotor 309 of this embodiment has a basic configuration similar to that of the above embodiment, and therefore can provide a basic effect similar to that of the above embodiment. However, in the rotor 309 of this embodiment, the magnet inner side surface 333d abuts against the outer circumferential surface of the core body 32A at two abutment portions 75 spaced apart in the circumferential direction, so that the pressing load acting between the magnet inner side surface 333d and the outer circumferential surface of the core body 32A can be dispersed to multiple locations. Therefore, when this configuration is adopted, the pressing load acting between the permanent magnet 333 and the outer circumferential surface of the core body 32A can be prevented from concentrating at one location, and deterioration and damage of the permanent magnet 333 can be more reliably prevented.

[0052] Furthermore, in the rotor 309 of this embodiment, the permanent magnet 333 is supported in a stable position by the core body 32B because the two abutment portions 75 spaced apart in the circumferential direction of the magnet inner surface 333d abut against the outer circumferential surface of the core body 32A. This makes it possible to suppress the permanent magnet 333 from shifting in position when the rotor 309 is in operation. Therefore, when this configuration is adopted, it is possible to suppress the generation of noise associated with the rattle of the permanent magnet 333, and to stabilize the magnetic performance of the rotor 309 due to the permanent magnet 333.

[0053] (Other embodiment 4) FIG. 11 is a cross-sectional view of Alternative Embodiment 4 corresponding to FIG. 7 of the above embodiment. In the rotor 409 of this embodiment, a configuration for forming a non-contact portion in the central region in the circumferential direction is provided on the peripheral wall 471a side of the magnet cover 471. The magnet outer side surface 433c of the permanent magnet 433 is formed by a uniform arc surface 67 as a whole. The arc surface 67 of the magnet outer side surface 433c is formed in an arc shape such that, when the permanent magnet 433 is assembled to the rotor core 32, the arc center is eccentric radially outward with respect to the axis (rotation axis) of the rotor 409, and the radius of curvature is smaller than the radius of curvature of an imaginary circle passing through the tips of the four salient poles 32B of the rotor core 32. In this embodiment, outer regions on both sides in the circumferential direction of the arcuate surface 67 of the magnet outer side surface 33c form the gradually separated portion.

[0054] In contrast, the magnet cover 471 is provided with two cover side abutment portions 91 that abut the magnet outer surface 433c at circumferentially inner positions of each spaced portion (outer region) of the magnet outer surface 433c, and a bulge portion 90 in which a portion of the inner surface bulges radially outward between the two cover side abutment portions 91. In this embodiment, the two cover side contact portions 91 form the contact portions of the magnet cover 471 , and the bulging portion 90 forms the non-contact portion of the magnet cover 471 .

[0055] In the rotor 409 of this embodiment, arc surfaces 67 are provided on both circumferential regions of the magnet outer surface 433c of the permanent magnet 433 such that the separation distance from the inner circumferential surface of the stator gradually increases from the circumferential central region toward the outside. Therefore, in the case of this embodiment as well, it is possible to suppress a sudden change in magnetic flux density when the permanent magnet 33 crosses the teeth 22 on the stator 8 side during rotation of the rotor 9.

[0056] In addition, the rotor 409 of this embodiment is provided with two cover-side abutment parts 91 that abut against the magnet outer surface 433c, and a bulging part 90 in which a part of the inner circumferential surface bulges outward in the radial direction between the two cover-side abutment parts 91. The part between the bulging part 90 and the magnet outer surface 433c is a non-abutment part. Therefore, in the case of this embodiment, too, the pressing load from the magnet cover 471 can be distributed to a plurality of places and transmitted to the permanent magnet 433. Therefore, the concentration of the pressing load from the magnet cover 471 can be suppressed, and deterioration and damage of the permanent magnet 433 can be prevented in advance. Therefore, even when the rotor 409 of this embodiment is adopted, the concentration of the pressing load from the magnet cover 471 to the permanent magnet 433 can be suppressed, and the cogging torque can be reduced.

[0057] The present invention is not limited to the above-described embodiment, and various design modifications are possible without departing from the spirit and scope of the present invention. In the above embodiment, one non-contact portion that does not abut against each other and two abutment portions arranged on both sides of the non-abutment portion are arranged between the outer surface of the permanent magnet and the magnet cover, but it is also possible to have two or more non-abutment portions and arrange an abutment portion on both sides of each non-abutment portion. In addition, in the above embodiment, the circumferential outer region of the outer magnet surface of the permanent magnet is formed by an arcuate surface of a constant outer diameter, but the gradual separation portion may be formed by a curved surface that does not have a constant outer diameter, so long as the separation distance from the inner circumferential surface of the stator gradually increases from the circumferential central region of the outer magnet surface outward. [Explanation of symbols]

[0058] Reference Signs List 1...motor unit, 2...motor, 3...reduction section, 4...controller, 5...motor case, 6...first motor case, 6a...opening, 7...second motor case, 7...target, 7a...opening, 8...stator, 9...rotor, 10...bottom, 11...connector, 16...outer flange section, 17...outer flange section, 20...stator core, 21...core main body section, 22...teeth, 23...insulator, 24...coil, 31...rotating shaft, 32...rotor core, 32A...core main body section, 32B...salient pole, 33...permanent magnet, 33a...side end face, 33b Inclined surface, 33c... magnet outer surface, 33d... magnet inner surface, 40... gear case, 40a... opening, 40b... side wall, 40c... bottom wall, 41... worm reduction mechanism, 42... gear housing, 43... opening, 44... worm shaft, 45... worm wheel, 46... bearing, 47... bearing, 48... output shaft, 48a... spline, 49... bearing boss, 52... rib, 61... magnetic detection element, 62... controller board, 63... cover, 65... maximum outer diameter portion, 66... ​​flat surface, 67... arc surface, 68... arc surface, 69... arc surface, 70... load receiving block, 70A... annular portion, 70B... leg portion, 71...magnet cover, 71a...circumferential wall, 71b...flange portion, 71c...flange portion, 73...groove, 73a...engagement portion, 74...locking claw, 75...contact portion, 90...bulge portion, 91...cover side contact portion, 109...rotor, 133...permanent magnet, 133c...magnet outer surface, 209...rotor, 233...permanent magnet, 233c...magnet outer surface, 309...rotor, 333...permanent magnet, 333d...magnet inner surface, 409...rotor, 433...permanent magnet, 433c...magnet outer surface, 471...magnet cover, 471a...circumferential wall, A1...central region, A2...outer region, C...axis center

Claims

1. A rotor rotatably disposed on an inner periphery of an annular stator, a rotor core having a substantially annular core body and a plurality of salient poles protruding in a radial direction from an outer periphery of the core body; a permanent magnet disposed between each of the salient poles adjacent to each other in the circumferential direction of the rotor core; a magnet cover that covers the rotor core and the outer side of the permanent magnet, the permanent magnet has a gradual separation portion in which the separation distance from the inner peripheral surface of the stator gradually increases from a circumferential central region toward the outside in both circumferential regions of the magnet outer surface facing the inner peripheral surface of the magnet cover, The magnet outer surface and the magnet cover are provided with at least one non-contact portion that does not contact each other between the two gradually separated portions of the magnet outer surface, and a plurality of contact portions that contact each other on both sides of the non-contact portion in the circumferential direction, a maximum outer diameter portion having a maximum length from a center position in the radial direction of the rotor core is provided at a circumferentially inner position of each of the gradually separated portions on the outer surface of the magnet; a small outer diameter portion is provided between the two maximum outer diameter portions on the outer surface of the magnet, the small outer diameter portion having a length from a center position in a radial direction of the rotor core shorter than the maximum outer diameter portion; the two maximum outer diameter portions constitute the abutment portion on the outer surface of the magnet, and the small outer diameter portion constitutes the non-abutment portion on the outer surface of the magnet, A rotor according to claim 1, wherein the small outer diameter portion is formed by a flat surface that linearly connects the two maximum outer diameter portions when viewed in the axial direction.

2. A rotor rotatably disposed on an inner periphery of an annular stator, a rotor core having a substantially annular core body and a plurality of salient poles protruding in a radial direction from an outer periphery of the core body; a permanent magnet disposed between each of the salient poles adjacent to each other in the circumferential direction of the rotor core; a magnet cover that covers the rotor core and the outer side of the permanent magnet, the permanent magnet has a gradual separation portion in which the separation distance from the inner peripheral surface of the stator gradually increases from a circumferential central region toward the outside in both circumferential regions of the magnet outer surface facing the inner peripheral surface of the magnet cover, The magnet outer surface and the magnet cover are provided with at least one non-contact portion that does not contact each other between the two gradually separated portions of the magnet outer surface, and a plurality of contact portions that contact each other on both sides of the non-contact portion in the circumferential direction, a maximum outer diameter portion having a maximum length from a center position in the radial direction of the rotor core is provided at a circumferentially inner position of each of the gradually separated portions on the outer surface of the magnet; a small outer diameter portion is provided between the two maximum outer diameter portions on the outer surface of the magnet, the small outer diameter portion having a length from a center position in a radial direction of the rotor core shorter than the maximum outer diameter portion; the two maximum outer diameter portions constitute the abutment portion on the outer surface of the magnet, and the small outer diameter portion constitutes the non-abutment portion on the outer surface of the magnet, The rotor is characterized in that the small outer diameter portion is formed by a radially outwardly convex arc surface having a radius of curvature larger than that of the inner peripheral surface of the magnet cover.

3. A rotor rotatably disposed on an inner periphery of an annular stator, a rotor core having a substantially annular core body and a plurality of salient poles protruding in a radial direction from an outer periphery of the core body; a permanent magnet disposed between each of the salient poles adjacent to each other in the circumferential direction of the rotor core; a magnet cover that covers the rotor core and the outer side of the permanent magnet, the permanent magnet has a gradual separation portion in which the separation distance from the inner peripheral surface of the stator gradually increases from a circumferential central region toward the outside in both circumferential regions of the magnet outer surface facing the inner peripheral surface of the magnet cover, The magnet outer surface and the magnet cover are provided with at least one non-contact portion that does not contact each other between the two gradually separated portions of the magnet outer surface, and a plurality of contact portions that contact each other on both sides of the non-contact portion in the circumferential direction, The magnet cover is provided with two cover-side abutment portions that abut against the magnet outer surface at circumferentially inner positions of each spaced portion of the magnet outer surface, and a bulging portion in which a part of an inner circumferential surface bulges radially outward between the two cover-side abutment portions, a rotor, characterized in that the cover-side abutment portion constitutes the abutment portion of the magnet cover, and the bulge portion constitutes the non-abutment portion of the magnet cover.

4. 4. A rotor as claimed in claim 1, characterized in that an inner magnet surface of the permanent magnet facing the outer peripheral surface of the core body portion is formed by an arcuate surface having an inner diameter larger than the outer diameter of the outer peripheral surface of the core body portion, and a circumferential central region of the inner magnet surface abuts against the outer peripheral surface of the core body portion.

5. A rotor according to any one of claims 1 to 4; a stator disposed on an outer periphery of the rotor and configured to generate a magnetic field.

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