Rotor, motor, and production method for rotor

Abstract

According to the embodiments, a rotor (10) comprises a rotor core (20), a rotary shaft (40), and a plurality of permanent magnets (30). The rotor core (20) has a shaft hole and a plurality of magnet provision holes (21). The rotary shaft (40) is cylindrical. At each magnet provision hole (21), the width of the magnet provision hole (21) in the direction orthogonal to the radial direction of the rotary shaft (40) at the magnet provision hole (21) is greater than the width of the permanent magnets (30) in the same direction. In a first region (R1), the permanent magnets (30) are provided in the magnet provision holes (21) so as to be offset clockwise in the circumferential direction as seen in plan view from the extension direction of the rotary shaft (40). In a second region (R2), the permanent magnets (30) are provided in the magnet provision holes (21) so as to be offset counterclockwise in the circumferential direction as seen in plan view from the extension direction of the rotary shaft (40).

Description

Rotor, motor, and rotor manufacturing method

[0001] The present disclosure relates to a rotor, a motor, and a method for manufacturing a rotor, and more particularly to a rotor including a plurality of permanent magnets, a motor including the rotor, and a method for manufacturing a rotor.

[0002] Patent Document 1 discloses a rotor having a plurality of permanent magnets, and an inner rotor type synchronous motor having a rotor.

[0003] In the rotor of Patent Document 1, multiple rotor magnets are attached to magnet accommodating holes (magnet placement holes) formed near the outer periphery of the rotor core. In the rotor of Patent Document 1, the multiple magnet accommodating holes are provided so that the magnetic pole centers are offset in order to reduce torque ripple.

[0004] JP 2013-132154 A

[0005] However, in the rotor of Patent Document 1, the circumferential spacing between two magnet accommodating holes adjacent to each other in the circumferential direction of the rotor in the rotor core is not uniform, which can cause cogging torque.

[0006] The present disclosure provides a rotor, a motor, and a method for manufacturing a rotor that can reduce cogging torque.

[0007] A rotor according to one aspect of the present disclosure includes a rotor core, a rotating shaft, and a plurality of permanent magnets. The rotor core has an axial hole and a plurality of magnet arrangement holes. The rotating shaft is disposed in the axial hole of the rotor core and is cylindrical. The plurality of permanent magnets correspond one-to-one to the plurality of magnet arrangement holes. In a plan view from a first direction, for any one of the plurality of magnet arrangement holes, the width of one magnet arrangement hole in a second direction is greater than the width of a corresponding permanent magnet in the second direction. The first direction is the axial direction of the rotating shaft. The second direction is perpendicular to the radial direction of the rotating shaft for one magnet arrangement hole. In a first region of the rotor core, in a plan view from the first direction, the plurality of permanent magnets are disposed in each of the plurality of magnet arrangement holes, offset in a clockwise direction circumferentially of the rotating shaft. The first region and the second region are defined by an imaginary plane. The imaginary plane passes through the axial hole of the rotor core but does not pass through any of the plurality of permanent magnets. In the second region of the rotor core, the plurality of permanent magnets are arranged in the plurality of magnet arrangement holes so as to be offset in the counterclockwise direction around the rotation axis in a plan view from the first direction.

[0008] A motor according to one aspect of the present disclosure includes the rotor described above and a stator. The stator is disposed around the rotor core. The stator includes a plurality of coils. The number of the plurality of coils is equal to or greater than the number of the plurality of permanent magnets.

[0009] A rotor manufacturing method according to one aspect of the present disclosure is a method for manufacturing a rotor including a rotating shaft, a rotor core, and a plurality of permanent magnets. The rotor manufacturing method includes a first step, a second step, and a third step. In the first step, a rotor core is prepared having a shaft hole corresponding to the rotating shaft and a plurality of magnet arrangement holes corresponding one-to-one to the plurality of permanent magnets. In the second step, a first magnet and a second magnet among the plurality of permanent magnets are inserted into each of two magnet arrangement holes adjacent to each other in the circumferential direction of the rotating shaft so that a first magnetic pole of the first magnet faces a second magnetic pole of the second magnet, the second magnetic pole having the same magnetic pole as the first magnetic pole, in the circumferential direction of the rotating shaft. In the third step, the plurality of permanent magnets are inserted into each of the first region and the second region so that two adjacent permanent magnets among the plurality of permanent magnets in the circumferential direction of the rotating shaft face each other in the circumferential direction of the rotating shaft. The first region and the second region are defined by an imaginary plane passing through the shaft hole and between the first magnet and the second magnet. In the third step, the magnets are inserted into the first region, starting with the magnet arrangement hole closest to the first magnet in the circumferential direction of the rotation shaft. The first region includes the first magnet. In the third step, the magnets are inserted into the second region, starting with the magnet arrangement hole closest to the second magnet in the circumferential direction of the rotation shaft.

[0010] According to the rotor, motor, and rotor manufacturing method according to one aspect of the present disclosure, it is possible to reduce cogging torque in a motor or a motor including a rotor.

[0011] FIG. 1 is a schematic plan view of a motor according to an embodiment. FIG. 2 is a schematic plan view of a rotor according to an embodiment. FIG. 3 is an exploded perspective view of the rotor. FIG. 4 is a schematic cross-sectional view of a rotor core in the rotor, corresponding to the X1-X1 cross section in FIG. 2. FIG. 5 is an enlarged plan view of a portion of the rotor. FIG. 6 is an enlarged plan view of a portion of the rotor different from FIG. 5. FIG. 7 is a schematic plan view showing a state in which two permanent magnets are attached to the rotor core in the rotor. FIG. 8 is a schematic explanatory diagram showing a state in which four permanent magnets are attached to the rotor core in the rotor. FIG. 9 is a schematic cross-sectional view of a rotor core of a rotor according to a modified example.

[0012] Hereinafter, rotors, motors, and rotor manufacturing methods according to embodiments of the present disclosure will be described in detail with reference to the drawings. However, the drawings described in the following embodiments are schematic diagrams, and the ratios of the sizes and thicknesses of the components do not necessarily reflect the actual dimensional ratios. Note that the configurations described in the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0013] (Embodiment) (1) Motor A motor 1 according to an embodiment is a brushless motor. As shown in Fig. 1, the motor 1 includes a stator 2 and a rotor 10 according to an embodiment. The stator 2 is disposed around a rotor core 20 of the rotor 10. Fig. 1 is a schematic plan view of the motor 1 as seen from the direction in which a rotation shaft 40 of the rotor 10 extends, i.e., the axial direction D1 of the rotation shaft 40 (hereinafter referred to as the "first direction D1").

[0014] The rotor 10 has a rotor core 20, a plurality of (ten in FIG. 1 ) permanent magnets 30, and a rotating shaft 40. The plurality of permanent magnets 30 are held in the rotor core 20. The stator 2 has a stator core 60 and a plurality of (twelve in FIG. 1 ) coils 69. The stator core 60 is arranged around the rotor core 20. The plurality of coils 69 are wound around the stator core 60. The difference between the number of coils 69 and the number of permanent magnets 30 is two or more (two in FIG. 1 ).

[0015] The rotor 10 rotates relative to the stator 2. That is, the rotor 10 rotates when magnetic flux (magnetic force) generated from the multiple coils 69 acts on the multiple permanent magnets 30. The rotational force (driving force) of the rotor 10 is output from the rotating shaft 40 to the outside of the motor 1.

[0016] (2) Rotor Fig. 2 is a schematic plan view of the rotor 10, and Fig. 3 is an exploded perspective view of the rotor 10. As shown in Fig. 2 and Fig. 3, the rotor 10 includes a rotor core 20, a rotating shaft 40, and a plurality of permanent magnets 30. Note that Fig. 2 shows the rotor core 20 and the plurality of permanent magnets 30, but does not illustrate the rotating shaft 40.

[0017] (2.1) Rotor Core FIG. 4 is a schematic cross-sectional view of the rotor core 20 in the rotor 10, corresponding to the X1-X1 cross section in FIG. 2. FIG. 5 is an enlarged plan view of the vicinity of the permanent magnet 34a in the rotor 10, and FIG. 6 is an enlarged plan view of the vicinity of the permanent magnet 35a in the rotor 10. The rotor core 20 is formed in a cylindrical shape. As shown in FIG. 4, the rotor core 20 is a so-called laminated core in which a plurality of steel plates 23 are stacked along a first direction D1. Each of the plurality of steel plates 23 corresponds to an example of a metal plate of the present disclosure. As shown in FIG. 4, the stacking direction of the plurality of steel plates 23 is the first direction D1. The plurality of steel plates 23 are formed, for example, by rolling in which they are pressed in the first direction D1 and stretched in a direction perpendicular to the first direction D1 (hereinafter referred to as the "rolling direction"). The metal plate of the present disclosure is not limited to the steel plate 23 in this embodiment, but may be formed of other metals used in laminated cores (for example, alloy plates such as permendur or amorphous).

[0018] The rotor core 20 has an end face 20 a on one side in the first direction D1. The rotor core 20 has an end face 20 a and an end face 20 b on both ends in the first direction D1. As shown in FIG. 3 , an axial hole 100 is formed in the center of the rotor core 20, penetrating the rotor core 20 in the first direction D1 and opening at the end face 20 a and the end face 20 b.

[0019] As shown in FIGS. 2 and 3 , the rotor core 20 has a plurality of magnet arrangement holes 21 (ten in FIGS. 2 and 3 ). Each of the magnet arrangement holes 21 is rectangular, for example, when viewed from a first direction D1. More specifically, the longitudinal direction of each of the magnet arrangement holes 21 is the radial direction of the rotor core 20 when viewed from the first direction D1. The lateral direction of each of the magnet arrangement holes 21 is the circumferential direction D2 of the rotor core 20 (more specifically, a second direction perpendicular to the radial direction of the rotor core 20) when viewed from the first direction D1. Here, the circumferential direction D2 of the rotor core 20 is the direction along the circumference of a circle centered at the center of rotation A1 of the rotor 10 when viewed from the first direction D1. The center of rotation A1 of the rotor 10 is, for example, the axis of the rotation shaft 40. 5 and 6 , the width d1 of each of the plurality of magnet arrangement holes 21 in the radial direction of the rotor core 20 is greater than the width d2 of each of the plurality of magnet arrangement holes 21 in a second direction perpendicular to the radial direction of the rotor core 20. In this embodiment, the radial direction of the rotating shaft 40 and the radial direction of the rotor core 20 coincide with each other, and the circumferential direction D2 of the rotating shaft 40 and the circumferential direction D2 of the rotor core 20 coincide with each other.

[0020] 5 and 6 , the rotor core 20 has a third surface 21a and a fourth surface 21b facing each other in the circumferential direction D2 as inner circumferential surfaces of each of the plurality of magnet arrangement holes 21. In a plan view from the first direction D1, the third surface 21a and the fourth surface 21b are arranged clockwise in this order. That is, in the rotor core 20, the third surfaces 21a and the fourth surfaces 21b are arranged alternately in the circumferential direction D2.

[0021] Each of the plurality of magnet arrangement holes 21 is open, for example, to end faces 20a and 20b, which are both ends in the first direction D1 of the rotor core 20. Note that in the rotor core 20, each of the plurality of magnet arrangement holes 21 may be, for example, a rectangular parallelepiped recess that is open to the end face 20a of the rotor core 20.

[0022] The multiple magnet arrangement holes 21 are evenly arranged in the circumferential direction D2 of the rotor core 20. "The multiple magnet arrangement holes 21 are evenly arranged in the circumferential direction D2 of the rotor core 20" means that when the rotor core 20 and a rotor core 20 rotated by a predetermined angle about the rotation center A1 of the rotor 10 are overlapped, the multiple magnet arrangement holes 21 in the two rotor cores 20 overlap one-to-one. Here, the predetermined angle is, for example, an angle obtained by dividing 360° by the number of magnet arrangement holes 21 (10 in this embodiment), specifically, 36 degrees. "The multiple magnet arrangement holes 21 overlap between the rotor core 20 and a rotor core 20 rotated by a predetermined angle about the rotation center A1 of the rotor 10 as the rotation axis" means that all of the multiple magnet arrangement holes 21 in the rotor core 20 rotated by the predetermined angle overlap with any of the multiple magnet arrangement holes 21 in the rotor core 20 before rotation, and the size of each overlapping area is equal to or larger than the size of the permanent magnet 30.

[0023] (2.2) Rotating Shaft The rotating shaft 40 is a cylindrical member, and is, for example, a round bar-shaped member as shown in FIG. 3 . Note that "the rotating shaft 40 is cylindrical" does not only mean that the rotating shaft 40 is completely rotationally symmetrical with respect to the center of rotation A1 of the rotor 10, but also means that when the rotating shaft 40 and another rotating shaft 40 rotated by a predetermined angle around the center of rotation A1 of the rotor 10 as the rotation axis are overlapped with each other, 50% or more of the rotating shaft 40 overlaps with the center of rotation A1 of the rotor 10. The rotating shaft 40 is disposed in the axial hole 100 of the rotor core 20. The rotating shaft 40 cannot move relative to the rotor core 20.

[0024] (2.3) Permanent Magnets The permanent magnets 30 are arranged in a one-to-one relationship in the magnet arrangement holes 21. The permanent magnets 30 are, for example, rare earth magnets containing rare earth, such as neodymium magnets.

[0025] Each of the multiple permanent magnets 30 has, for example, a rectangular parallelepiped shape. More specifically, when viewed from the first direction D1, each of the multiple permanent magnets 30 has a rectangular shape with its longitudinal direction aligned with the radial direction of the rotor core 20 in the corresponding magnet arrangement hole 21. That is, as shown in FIGS. 5 and 6 , for each of the multiple permanent magnets 30, the width d3 of the permanent magnet 30 along the radial direction of the rotor core 20 in the corresponding magnet arrangement hole 21 is greater than the width d4 of the rotor core 20 in the second direction in the corresponding magnet arrangement hole 21. This allows the effective area of ​​the multiple permanent magnets 30 in the rotor 10 to be increased. This therefore increases the density of magnetic flux in the rotor 10, thereby improving torque.

[0026] The width d4 in the second direction of each of the multiple permanent magnets 30 is smaller than the width d2 in the second direction of each of the multiple magnet arrangement holes 21. This makes it easy to arrange each of the multiple permanent magnets 30 in the corresponding magnet arrangement hole 21 of the rotor core 20 in the rotor 10 according to this embodiment. Note that the width d3 in the radial direction of each of the multiple permanent magnets 30 is smaller than the width d1 in the radial direction of each of the multiple magnet arrangement holes 21. This makes it easy to arrange each of the multiple permanent magnets 30 in the corresponding magnet arrangement hole 21 of the rotor core 20 in the rotor 10 according to this embodiment.

[0027] Each of the multiple permanent magnets 30 has a first surface 31 and a second surface 32. In each of the multiple permanent magnets 30, the first surface 31 and the second surface 32 are arranged in this order in the clockwise circumferential direction of the rotor core 20 when viewed from a plane in the first direction D1. In each of the multiple permanent magnets 30, the first surface 31 and the second surface 32 have magnetic poles that are different from each other. Specifically, as shown in FIG. 5 , when the first surface 31 of the permanent magnet 30 is the magnetic pole 33b that is an S pole, the second surface 32 is the magnetic pole 33a that is an N pole. Also, as shown in FIG. 6 , when the first surface 31 of the permanent magnet 30 is the magnetic pole 33a that is an N pole, the second surface 32 is the magnetic pole 33b that is an S pole.

[0028] (2.4) Arrangement of Permanent Magnets Among the multiple permanent magnets 30, two adjacent permanent magnets 30 in the circumferential direction D2 have the same magnetic poles facing each other, as shown in Fig. 2. That is, in two adjacent permanent magnets 30, i.e., a first permanent magnet 30 and a second permanent magnet 30, the magnetic pole 33a of the first permanent magnet 30 faces the magnetic pole 33a of the second permanent magnet 30, or the magnetic pole 33b of the first permanent magnet 30 faces the magnetic pole 33b of the second permanent magnet 30. In other words, in two adjacent permanent magnets 30, the first surface 31 of the first permanent magnet 30 and the second surface 32 of the second permanent magnet 30 have the same magnetic pole, and the second surface 32 of the first permanent magnet 30 and the first surface 31 of the second permanent magnet 30 have the same magnetic pole.

[0029] The rotor core 20 has a first region R1 and a second region R2 defined by an imaginary plane P1. The imaginary plane P1 passes through the axial hole 100 of the rotor core 20 but does not pass through any of the magnet arrangement holes 21. More specifically, the imaginary plane P1 passes through the rotation center A1 of the rotor 10. Note that "the imaginary plane P1 passes through the rotation center A1 of the rotor 10" includes cases where the imaginary plane P1 passes near the rotation center A1 of the rotor 10. The imaginary plane P1 may also pass through the axis of the rotation shaft 40. "The imaginary plane P1 passes through the axis of the rotation shaft 40" includes cases where the imaginary plane P1 passes near the axis of the rotation shaft 40. The first region R1 and the second region R2 each include half (five in FIG. 2 ) of the multiple magnet arrangement holes 21. That is, the first region R1 and the second region R2 include the same number of magnet arrangement holes 21. In the first region R1, as shown in FIGS. 2 and 5 , the multiple permanent magnets 30 are arranged in each of the multiple magnet arrangement holes 21 with a clockwise offset in the circumferential direction D2 in a plan view from the first direction D1. Here, "the multiple permanent magnets 30 are arranged in each of the multiple magnet arrangement holes 21 with a clockwise offset in the circumferential direction D2" means that, as shown in FIG. 5 , in a plan view from the first direction D1, the distance d5 between the third surface 21a of the magnet arrangement hole 21 and the first surface 31 of the permanent magnet 30 is greater than the distance between the fourth surface 21b of the magnet arrangement hole 21 and the second surface 32 of the permanent magnet 30. Here, the distance between the fourth surface 21b of the magnet arrangement hole 21 and the second surface 32 of the permanent magnet 30 may be zero. The multiple permanent magnets 34b to 34e included in the first region R1 are arranged in each of the multiple magnet arrangement holes 21 with a clockwise offset in the circumferential direction D2, similar to the permanent magnet 34a shown in FIG. 5 . That is, the multiple permanent magnets 34a to 34e included in the first region R1 are all arranged in the multiple magnet arrangement holes 21 while being shifted clockwise in the circumferential direction D2.

[0030] 2, in the first region R1, each of the plurality of permanent magnets 34a to 34e may be in contact with the fourth surface 21b of the magnet arrangement hole 21 and the second surface 32 of the permanent magnet 30. This reduces the variation in the distance between two adjacent permanent magnets 30 in the circumferential direction D2 in the first region R1, thereby reducing the cogging torque.

[0031] 2 and 6 , in the second region R2, the permanent magnets 30 are arranged in each of the magnet arrangement holes 21 while being offset counterclockwise in the circumferential direction D2 in a plan view from the first direction D1. Here, "the permanent magnets 30 are arranged in each of the magnet arrangement holes 21 while being offset counterclockwise in the circumferential direction D2" means that, as shown in FIG. 6 , in a plan view from the first direction D1, the distance d6 between the fourth surface 21b of the magnet arrangement hole 21 and the second surface 32 of the permanent magnet 30 is greater than the distance between the third surface 21a of the magnet arrangement hole 21 and the first surface 31 of the permanent magnet 30. Here, the third surface 21a of the magnet arrangement hole 21 and the first surface 31 of the permanent magnet 30 may be in contact with each other, and the distance between the third surface 21a of the magnet arrangement hole 21 and the first surface 31 of the permanent magnet 30 may be zero. 2, the multiple permanent magnets 35b to 35e included in the second region R2 are arranged in each of the multiple magnet arrangement holes 21 with a shift in the counterclockwise direction of the circumferential direction D2, similar to the permanent magnet 35a shown in Fig. 6. That is, the multiple permanent magnets 35a to 35e included in the second region R2 are all arranged in each of the multiple magnet arrangement holes 21 with a shift in the counterclockwise direction of the circumferential direction D2.

[0032] 2, in the second region R2, each of the plurality of permanent magnets 35a to 35e may be in contact with the third surface 21a of the magnet arrangement hole 21 and the first surface 31 of the permanent magnet 30. This reduces the variation in the distance between two adjacent permanent magnets 30 in the circumferential direction D2 in the first region R1, thereby reducing the cogging torque.

[0033] In the motor 1 according to this embodiment, the arrangement of the multiple permanent magnets 30 on the rotor 10 is not rotationally symmetrical with respect to the center of rotation A1 of the rotor 10. In particular, the distance between the centers of two adjacent permanent magnets 30 in the circumferential direction D2 is wider between the adjacent permanent magnets 34a and 35a across the imaginary plane P1, and narrower between the adjacent permanent magnets 34e and 35e. Therefore, in the motor 1 according to this embodiment, the magnetomotive force distribution of the rotor 10 based on the above-described features makes it possible to reduce cogging torque.

[0034] (3) Rotor Manufacturing Method Next, a method for manufacturing the rotor 10 will be described. However, the manufacturing method described below is an example, and the order of multiple steps or the order of some of the steps may be changed. Note that the manufacturing method described below is automated using various manufacturing devices, but all or some of the steps may also be performed manually. Also, a description of the manufacturing method for the rotor core 20 will be omitted.

[0035] Fig. 7 is a schematic plan view showing the state in which two permanent magnets 34a and 35a are attached to the rotor core 20 in the rotor 10. Fig. 8 is a schematic explanatory diagram showing the state in which four permanent magnets 34a, 35a, 34b, and 35b are attached to the rotor core 20 in the rotor 10. The manufacturing method of the rotor 10 (hereinafter abbreviated as "manufacturing method") described below includes at least a first step, a second step, and a third step.

[0036] In the first step, a rotor core 20 is prepared, which has a shaft hole 100 corresponding to the rotating shaft 40 and a plurality of magnet arrangement holes 21. The plurality of magnet arrangement holes 21 correspond one-to-one to an unspecified number of permanent magnets 30. In the first step, the plurality of magnet arrangement holes 21 are arranged at equal angular intervals in the circumferential direction D2 of the rotor core 20. Here, "arranging the plurality of magnet arrangement holes 21 at equal angular intervals" means that the plurality of magnet arrangement holes 21 in the rotor core 20 are n-fold symmetric (n is the number of magnet arrangement holes 21) with respect to the center of rotation A1 of the rotor 10.

[0037] In the second step, two of the permanent magnets 30, the permanent magnets 34a and 35a, are attached to the rotor core 20. As shown in FIG. 7 , in the second step, the permanent magnets 34a and 35a are inserted into two of the magnet arrangement holes 21 of the rotor core 20 that are adjacent to each other in the circumferential direction D2. At this time, the permanent magnets 34a and 35a are inserted into the rotor core 20 so that the permanent magnets 35a, 34a are aligned clockwise in this order in a plan view from the first direction D1. The permanent magnets 34a and 35a are also inserted into the rotor core 20 so that the magnetic poles 33b of the permanent magnets 34a and 35a face each other in the circumferential direction D2. The permanent magnets 34a and 35a correspond to an example of a first magnet in the present disclosure. The permanent magnets 35a correspond to an example of a second magnet in the present disclosure. Furthermore, the magnetic pole 33b of the permanent magnet 34a corresponds to an example of a first magnetic pole in the present disclosure, and the magnetic pole 33b of the permanent magnet 35a corresponds to an example of a second magnetic pole in the present disclosure.

[0038] Because the magnetic pole 33b of the permanent magnet 34a and the magnetic pole 33b of the permanent magnet 35a are the same magnetic pole 33b, a repulsive force is generated between the permanent magnets 34a and 35a. As a result, in the permanent magnet 34a, the repulsive force from the permanent magnet 35a causes the distance d5 (see FIG. 5 ) between the first surface 31 of the permanent magnet 34a and the third surface 21a of the magnet arrangement hole 21 to be greater than the distance between the second surface 32 of the permanent magnet 34a and the fourth surface 21b of the magnet arrangement hole 21. Therefore, the permanent magnets 34a are arranged in the magnet arrangement hole 21 so as to be offset clockwise in the circumferential direction D2 when viewed in a plan view from the first direction D1. Similarly, in the permanent magnet 35a, due to the repulsive force from the permanent magnet 34a, the distance d6 (see FIG. 6) between the second surface 32 of the permanent magnet 35a and the fourth surface 21b of the magnet arrangement hole 21 is greater than the distance between the first surface 31 of the permanent magnet 35a and the third surface 21a of the magnet arrangement hole 21. Therefore, the permanent magnet 35a is arranged in the magnet arrangement hole 21 offset counterclockwise in the circumferential direction D2 in a plan view from the first direction D1.

[0039] That is, in the second step, due to the repulsive force between the permanent magnets 34a and 35a, when viewed in a plane from the first direction D1, the permanent magnet 34a can be arranged in the magnet arrangement hole 21 with a clockwise shift in the circumferential direction D2, and the permanent magnet 35a can be arranged in the magnet arrangement hole 21 with a counterclockwise shift in the circumferential direction D2.

[0040] In a third step, a plurality of permanent magnets 30 are attached to the first region R1 and the second region R2 of the rotor core 20. Here, an imaginary plane P1, which is the boundary between the first region R1 and the second region R2, passes through the space between the magnet arrangement hole 21 into which the permanent magnet 34a is inserted and the magnet arrangement hole 21 into which the permanent magnet 35a is inserted, and through the axial hole 100. More specifically, the imaginary plane P1 passes through the rotation center A1 of the rotor 10. Note that "the imaginary plane P1 passes through the rotation center A1 of the rotor 10" includes the case where the imaginary plane P1 passes near the rotation center A1 of the rotor 10. Furthermore, the imaginary plane P1 may pass through the axis of the rotation shaft 40. "the imaginary plane P1 passes through the axis of the rotation shaft 40" includes the case where the imaginary plane P1 passes near the axis of the rotation shaft 40.

[0041] The first region R1 is one of the two regions of the rotor core 20 defined by the imaginary plane P1 that includes the permanent magnets 34a. More specifically, the first region R1 includes half (five in FIG. 8 ) of the multiple magnet arrangement holes 21 in the rotor core 20. The second region R2 is one of the two regions of the rotor core 20 defined by the imaginary plane P1 that is not the first region R1. More specifically, the second region R2 is one of the regions of the rotor core 20 that includes the permanent magnets 35a. The second region R2 includes half (five in FIG. 8 ) of the multiple magnet arrangement holes 21 in the rotor core 20.

[0042] In the third step, the plurality of permanent magnets 30 are inserted so that two adjacent permanent magnets 30 in the circumferential direction D2 have the same magnetic poles facing each other in the circumferential direction D2.

[0043] In the third step, in the first region R1, the permanent magnets 30 are inserted one by one in the magnet arrangement holes 21, starting from the magnet arrangement hole 21 closest to the permanent magnet 34a in the circumferential direction D2. More specifically, in the third step, in the first region R1, the permanent magnets 30 are arranged in the rotor core 20 in the order of the permanent magnets 34b, 34c, 34d, and 34e (see FIG. 2).

[0044] 8, in the third step, the permanent magnet 34b is inserted into the magnet arrangement hole 21 adjacent to the magnet arrangement hole 21 into which the permanent magnet 34a is inserted so that the second surface 32 of the permanent magnet 34a and the first surface 31 of the permanent magnet 34b have the same magnetic pole 33a. As a result, the repulsive force from the permanent magnet 34a allows the permanent magnet 34b to be arranged in the magnet arrangement hole 21 with a clockwise shift in the circumferential direction D2 when viewed from above in the first direction D1.

[0045] In the third step, the permanent magnet 34c is inserted into the magnet arrangement hole 21 so that the first surface 31 of the permanent magnet 34c and the second surface 32 of the permanent magnet 34b have the same magnetic pole 33b. Therefore, due to the repulsive force from the permanent magnet 34b, the permanent magnet 34c can be arranged in the magnet arrangement hole 21 with a clockwise offset in the circumferential direction D2 when viewed in a plan view from the first direction D1. Similarly, in the third step, the permanent magnet 34d is inserted into the magnet arrangement hole 21 so that the first surface 31 of the permanent magnet 34d and the second surface 32 of the permanent magnet 34c have the same magnetic pole 33a. Therefore, due to the repulsive force from the permanent magnet 34c, the permanent magnet 34d can be arranged in the magnet arrangement hole 21 with a clockwise offset in the circumferential direction D2 when viewed in a plan view from the first direction D1. Similarly, in the third step, the permanent magnet 34e is inserted into the magnet arrangement hole 21 so that the first surface 31 of the permanent magnet 34e and the second surface 32 of the permanent magnet 34d have the same magnetic pole 33b. Therefore, due to the repulsive force from the permanent magnet 34d, the permanent magnet 34e can be arranged in the magnet arrangement hole 21 with a clockwise offset in the circumferential direction D2 when viewed in a plan view from the first direction D1.

[0046] That is, in the third step, in the first region R1, the permanent magnets 30 are inserted one by one in a predetermined order into the magnet arrangement holes 21. As a result, in the first region R1, due to the repulsive force between two permanent magnets 30 adjacent to each other in the circumferential direction D2, the permanent magnets 30 can be arranged in the magnet arrangement holes 21 with a clockwise offset in the circumferential direction D2 in a plan view from the first direction D1.

[0047] In the third step, the permanent magnets 30 are inserted one by one into the magnet arrangement holes 21 in the second region R2, starting from the magnet arrangement hole 21 closest to the permanent magnet 35a in the circumferential direction D2. More specifically, in the third step, the permanent magnets 30 are arranged in the rotor core 20 in the second region R2 in the order of the permanent magnets 35b, 35c, 35d, and 35e (see FIG. 2).

[0048] 8, the permanent magnet 35b is inserted into the magnet arrangement hole 21 adjacent to the magnet arrangement hole 21 into which the permanent magnet 35a is inserted so that the first surface 31 of the permanent magnet 35a and the second surface 32 of the permanent magnet 35b have the same magnetic pole 33a. As a result, the repulsive force from the permanent magnet 35a allows the permanent magnet 35b to be arranged in the magnet arrangement hole 21 offset counterclockwise in the circumferential direction D2 when viewed in a plan view from the first direction D1.

[0049] In the third step, the permanent magnet 35c is inserted into the magnet arrangement hole 21 so that the second surface 32 of the permanent magnet 35c and the first surface 31 of the permanent magnet 35b have the same magnetic pole 33b. Therefore, due to the repulsive force from the permanent magnet 35b, the permanent magnet 35c can be arranged in the magnet arrangement hole 21 with a counterclockwise offset in the circumferential direction D2 when viewed in plan from the first direction D1. Similarly, in the third step, the permanent magnet 35d is inserted into the magnet arrangement hole 21 so that the second surface 32 of the permanent magnet 35d and the first surface 31 of the permanent magnet 35c have the same magnetic pole 33a. Therefore, due to the repulsive force from the permanent magnet 35c, the permanent magnet 35d can be arranged in the magnet arrangement hole 21 with a counterclockwise offset in the circumferential direction D2 when viewed in plan from the first direction D1. Similarly, in the third step, the permanent magnet 35e is inserted into the magnet arrangement hole 21 so that the second surface 32 of the permanent magnet 35e and the first surface 31 of the permanent magnet 35d have the same magnetic pole 33b. Therefore, due to the repulsive force from the permanent magnet 35d, the permanent magnet 35e can be arranged in the magnet arrangement hole 21 with a counterclockwise shift in the circumferential direction D2 when viewed in a plan view from the first direction D1.

[0050] That is, in the third step, in the second region R2, the permanent magnets 30 are inserted one by one in a predetermined order into the magnet arrangement holes 21. As a result, in the second region R2, due to the repulsive force between two permanent magnets 30 adjacent in the circumferential direction D2, it becomes possible to arrange each of the permanent magnets 30 in the magnet arrangement holes 21 with a shift in the counterclockwise direction in the circumferential direction D2 when viewed in a plan view from the first direction D1.

[0051] After the third step, a resin layer may be formed by applying adhesive to the gaps between each of the permanent magnets 30 and the magnet placement holes 21 of the rotor core 20. By forming the resin layer, the relative positional relationship of the permanent magnets 30 can be further stabilized.

[0052] In the third step, the insertion of the permanent magnets 30 into the magnet arrangement holes 21 in the first region R1 and the insertion of the permanent magnets 30 into the magnet arrangement holes 21 in the second region R2 may be performed simultaneously, one by one. For example, in the third step, the insertion of the permanent magnet 34b into the rotor core 20 and the insertion of the permanent magnet 35b into the rotor core 20 may be performed simultaneously. Furthermore, for example, the permanent magnets 30 may be inserted alternately into the first region R1 and the second region R2, one by one. The order in which the permanent magnets 30 are inserted into the rotor core 20 is not limited to the above example, and any order may be used as long as the order in which the permanent magnets 30 are inserted into the magnet arrangement holes 21 in the first region R1 and the order in which the permanent magnets 30 are inserted into the magnet arrangement holes 21 in the second region R2 are the same as those described above.

[0053] (4) Other Components of the Motor The following describes the stator 2, which is a component of the motor 1 other than the rotor 10. As described above, the stator 2 has the stator core 60 and a plurality of coils 69 (12 coils in FIG. 1).

[0054] The stator core 60 is a so-called laminated core in which a plurality of steel plates are laminated in a first direction D1. As shown in Fig. 1, the stator core 60 has a plurality of teeth 61 (12 in Fig. 1) and an outer circumferential portion 62. The teeth 61 protrude inward from the outer circumferential portion 62 toward the rotation center A1 of the rotor 10. The teeth 61 are provided at equal intervals in the circumferential direction of the outer circumferential portion 62 (the rotation direction of the rotor 10). The teeth 61 correspond one-to-one to the coils 69. A corresponding coil 69 is wound around each of the teeth 61.

[0055] The outer peripheral portion 62 has, for example, a hollow cylindrical shape.

[0056] (5) Effects The rotor 10 according to the embodiment includes a rotor core 20, a rotating shaft 40, and a plurality of permanent magnets 30. The rotor core 20 has a shaft hole 100 and a plurality of magnet arrangement holes 21. The rotating shaft 40 is cylindrical and disposed in the shaft hole 100 of the rotor core 20. The plurality of permanent magnets 30 correspond one-to-one to the plurality of magnet arrangement holes 21. In a plan view from a first direction D1, which is the axial direction of the rotating shaft 40, for any one of the plurality of magnet arrangement holes 21, the width d2 of the magnet arrangement hole 21 in a second direction perpendicular to the radial direction of the rotating shaft 40 at the one magnet arrangement hole 21 is greater than the width d4 of the permanent magnet 30 corresponding to the one of the plurality of permanent magnets 30 in the second direction. In the first region R1 of the rotor core 20, in a plan view from the first direction D1, the multiple permanent magnets 30 are arranged in each of the multiple magnet arrangement holes 21 while being offset in the clockwise direction in the circumferential direction D2 of the rotating shaft 40. The first region R1 and the second region R2 are partitioned by an imaginary plane P1. The imaginary plane P1 passes through the axial hole 100 of the rotor core 20, but does not pass through any of the multiple permanent magnets 30. In the second region R2 of the rotor core 20, in a plan view from the first direction D1, the multiple permanent magnets 30 are arranged in each of the multiple magnet arrangement holes 21 while being offset in the counterclockwise direction in the circumferential direction D2 of the rotating shaft 40.

[0057] With the above configuration, in the rotor 10 according to this embodiment, the arrangement of the multiple permanent magnets 30 is not rotationally symmetrical with respect to the rotation center A1 of the rotor 10. Therefore, in the motor 1 including the rotor 10, it is possible to reduce cogging torque.

[0058] Furthermore, in the rotor 10 according to the embodiment, in a plan view from the first direction D1, each of the multiple permanent magnets 30 has a first surface 31 and a second surface 32 that face the circumferential direction D2 of the rotation shaft 40. In the plan view from the first direction D1, the first surface 31 and the second surface 32 of each of the multiple permanent magnets 30 are arranged in this order in the clockwise direction of the circumferential direction D2 of the rotation shaft 40. In the first region R1 of the rotor core 20, in a plan view from the first direction D1, the second surface 32 of each of the multiple permanent magnets 30 is in contact with a fourth surface 21b that is the inner circumferential surface of the multiple magnet arrangement holes 21 of the rotor core 20. In the second region R2 of the rotor core 20, in a plan view from the first direction D1, the first surface 31 of each of the multiple permanent magnets 30 is in contact with a third surface 21a that is the inner circumferential surface of the multiple magnet arrangement holes 21 of the rotor core 20. This makes it easy to arrange the multiple permanent magnets 30 in each of the first region R1 and the second region R2, making it possible to easily reduce the cogging torque.

[0059] Furthermore, in the rotor 10 according to this embodiment, the multiple magnet arrangement holes 21 are evenly arranged in the circumferential direction D2 of the rotating shaft 40. Therefore, in the rotor 10, it is not necessary to unevenly arrange the multiple magnet arrangement holes 21 in order to configure the arrangement of the multiple permanent magnets 30 as not rotationally symmetrical about the rotation center A1 of the rotor 10. Therefore, the shape of the rotor core 20 can be made rotationally symmetrical or nearly so about the rotation center A1 of the rotor 10, which makes it possible to reduce cogging torque.

[0060] Furthermore, in the rotor 10 according to this embodiment, in a plan view from the first direction D1, the longitudinal direction of each of the multiple permanent magnets 30 is the radial direction of the rotating shaft 40. This increases the effective area of ​​the permanent magnets 30 in the rotor 10, making it possible to increase the density of the magnetic flux. This in turn makes it possible to improve the torque of the rotor 10.

[0061] Furthermore, in the rotor 10 according to this embodiment, the rotor core 20 includes a plurality of steel plates 23 stacked in the first direction D1. This makes it possible to reduce iron loss due to eddy currents generated in the rotor core 20.

[0062] Furthermore, in the rotor 10 according to this embodiment, the plurality of permanent magnets 30 contain rare earth elements, which allows for a high density of magnetic flux in the permanent magnets 30. This reduces the cogging torque of the rotor 10 and also allows for an increase in torque.

[0063] The motor 1 according to the embodiment includes the rotor 10 according to the embodiment and a stator 2. The stator 2 is disposed around the rotor core 20. The stator 2 includes a plurality of coils 69. The difference between the number of the plurality of coils 69 and the number of the plurality of permanent magnets 30 is two or more. This makes it possible to reduce cogging torque in the motor 1 according to the embodiment.

[0064] The manufacturing method of the rotor 10 according to the embodiment is a method for manufacturing the rotor 10 including a rotating shaft 40, a rotor core 20, and a plurality of permanent magnets 30. The manufacturing method of the rotor 10 includes a first step, a second step, and a third step. In the first step, a rotor core 20 is prepared, which has a shaft hole 100 corresponding to the rotating shaft 40 and a plurality of magnet arrangement holes 21 corresponding one-to-one to the plurality of permanent magnets 30. In the second step, a permanent magnet 34 a and a permanent magnet 35 a of the plurality of permanent magnets 30 are inserted into two of the plurality of magnet arrangement holes 21 that are adjacent to each other in the circumferential direction D2 of the rotating shaft 40, so that the magnetic pole 33 b of the permanent magnet 34 a and the magnetic pole 33 b of the permanent magnet 35 a face each other in the circumferential direction D2 of the rotating shaft 40. In the third step, the multiple permanent magnets 30 are inserted into each of the first region R1 and the second region R2 so that two adjacent permanent magnets 30 in the circumferential direction D2 of the rotating shaft 40 have the same magnetic poles facing each other in the circumferential direction D2 of the rotating shaft 40. The first region R1 and the second region R2 are defined by an imaginary plane P1 that passes through the shaft hole 100 and the space between the permanent magnets 34a and 35a. In the third step, the multiple permanent magnets 30 are inserted into the first region R1, starting with the magnet arrangement hole 21 closest to the permanent magnet 34a in the circumferential direction D2 of the rotating shaft 40. The first region R1 includes the permanent magnet 34a. In the third step, the multiple permanent magnets 30 are inserted into the second region R2, starting with the magnet arrangement hole 21 closest to the permanent magnet 35a in the circumferential direction D2 of the rotating shaft 40.

[0065] According to the manufacturing method of the rotor 10 of the embodiment, it is possible to easily manufacture a rotor 10 in which the arrangement of the multiple permanent magnets 30 is not rotationally symmetrical with respect to the center of rotation A1 of the rotor 10 by utilizing the repulsive force between the multiple permanent magnets 30.

[0066] 9 is a schematic cross-sectional view of the rotor core 20 of the rotor 10 according to a modified example. In the rotor 10 according to the modified example, the rotor core 20 includes a steel plate 23a and a steel plate 23b having mutually different rolling directions.

[0067] In the rotor 10 according to the modified example, the rotor core 20 includes steel plates 23 a and 23 b. The steel plates 23 a and 23 b are stacked in the first direction D1. The steel plates 23 a and 23 b are formed by rolling.

[0068] The steel plate 23a is formed by rolling, in which the steel plate 23a is pressed in a first direction D1 and elongated in a direction D3 (hereinafter referred to as the "rolling direction D3") (see FIG. 9) perpendicular to the first direction D1. The steel plate 23b is formed by rolling, in which the steel plate 23a is pressed in the first direction D1 and elongated in a direction D4 (hereinafter referred to as the "rolling direction D4") (see FIG. 9) perpendicular to the first direction D1. The rolling direction D3 and the rolling direction D4 intersect (are perpendicular in FIG. 9), for example, when viewed from a plane in the first direction D1.

[0069] In the rotor 10 according to the modified example, the rolling direction D3 of the steel plate 23a and the rolling direction D4 of the steel plate 23b are not parallel to each other in the rotor core 20. More specifically, in a plan view from the first direction D1, the rolling direction D3 of the steel plate 23a and the rolling direction D4 of the steel plate 23b intersect with each other as shown in Fig. 9. The steel plate 23a corresponds to an example of the first metal plate of the present disclosure, and the steel plate 23b corresponds to an example of the second metal plate of the present disclosure.

[0070] The steel plates 23 formed by rolling may not have a completely uniform thickness. Therefore, if the rolling directions of the steel plates 23 in the rotor core 20 are aligned, the density of the multiple steel plates 23 in the first direction D1 may not be constant, which may result in bias in the magnetic properties of the rotor core 20 and cause cogging torque. In contrast, in the rotor 10 according to the modified example, the rolling direction D3 of the steel plates 23a and the rolling direction D4 of the steel plates 23b in the rotor core 20 are not parallel. Therefore, even if there is variation in the thickness of the steel plates 23a and the steel plates 23b, the density of the multiple steel plates 23 in the first direction D1 is likely to be uniform. Therefore, the rotor 10 according to the modified example can further reduce cogging torque. Of the plurality of steel plates 23, the rolling direction of the steel plates 23 other than the steel plates 23a and 23b may be parallel to the rolling direction D3, parallel to the rolling direction D4, or may not be parallel to either the rolling direction D3 or the rolling direction D4. This makes it possible to further reduce the cogging torque of the rotor 10.

[0071] In the manufacturing method of the rotor 10 according to the modified example, when preparing the rotor core 20, the steel plates 23a and 23b may be manufactured from the same rolled steel plate. Specifically, the steel plates 23a and 23b are each punched out from a single rolled steel plate. Then, when stacking the steel plates 23a and 23b, the steel plates 23a and 23b are rotated relative to each other so that the rolling direction D3 of the steel plate 23a and the rolling direction D4 of the steel plate 23b are not parallel to each other. This makes it possible to easily manufacture the rotor core 20 of the rotor 10 according to the modified example.

[0072] (2) Effects In the rotor 10 according to the modified example, each of the plurality of steel plates 23 is formed by rolling. The plurality of steel plates 23 includes a steel plate 23a and a steel plate 23b. In a plan view from the first direction D1, the rolling direction D3 of the steel plate 23a intersects with the rolling direction D4 of the steel plate 23b. This increases the uniformity of the magnetic properties of the rotor core 20, making it possible to further reduce cogging torque.

[0073] (Other Modifications of the Embodiments) In the rotor 10 and motor 1 according to the embodiments and modifications, the rotor 10 includes ten permanent magnets 30, but the number of permanent magnets 30 in the rotor 10 is not limited to ten and may be an even number of eight or less, or an even number of 12 or more. Similarly, the number of coils 69 in the stator 2 is not limited to 12 and may be 11 or less, or 13 or more. It is preferable that the difference between the number of permanent magnets 30 in the rotor 10 and the number of coils 69 in the stator 2 be two or more.

[0074] (Aspect) A rotor (10) according to a first aspect includes a rotor core (20), a rotating shaft (40), and a plurality of permanent magnets (30). The rotor core (20) has an axial hole (100) and a plurality of magnet arrangement holes (21). The rotating shaft (40) is arranged in the axial hole (100) of the rotor core (20) and is cylindrical. The plurality of permanent magnets (30) correspond one-to-one to the plurality of magnet arrangement holes (21). In a plan view from a first direction (D1), for any one of the plurality of magnet arrangement holes (21), a width (d2) of the magnet arrangement hole (21) in a second direction perpendicular to the radial direction of the rotating shaft (40) at the one magnet arrangement hole (21) is greater than a width (d4) of one of the plurality of permanent magnets (30) corresponding to the one of the plurality of magnet arrangement holes (21) in the second direction. The first direction (D1) is the axial direction of the rotating shaft (40). In the first region (R1) of the rotor core (20), in a plan view from the first direction (D1), the multiple permanent magnets (30) are arranged in each of the multiple magnet arrangement holes (21) with a shift in the clockwise direction of the circumferential direction (D2) of the rotating shaft (40). The first region (R1) and the second region (R2) are partitioned by an imaginary plane (P1). The imaginary plane (P1) passes through the axial hole (100) of the rotor core (20) but does not pass through any of the multiple permanent magnets (30). In the second region (R2) of the rotor core (20), in a plan view from the first direction (D1), the multiple permanent magnets (30) are arranged in each of the multiple magnet arrangement holes (21) with a shift in the counterclockwise direction of the circumferential direction (D2) of the rotating shaft (40).

[0075] According to the rotor (10) of the above aspect, the arrangement of the multiple permanent magnets (30) is not rotationally symmetrical with respect to the center of rotation (A1) of the rotor (10). Therefore, it is possible to reduce cogging torque in a motor (1) including the rotor (10).

[0076] In the rotor (10) according to the second aspect, in the first aspect, each of the plurality of permanent magnets (30) has a first surface (31) and a second surface (32) that face each other in a circumferential direction (D2) of the rotation shaft (40) when viewed from a first direction (D1). In each of the plurality of permanent magnets (30), when viewed from a first direction (D1), the first surface (31) and the second surface (32) are arranged in this order in a clockwise direction in the circumferential direction (D2) of the rotation shaft (40). In the first region (R1) of the rotor core (20), when viewed from a first direction (D1), the second surface (32) of each of the plurality of permanent magnets (30) contacts inner circumferential surfaces (21 b) of the plurality of magnet arrangement holes (21) of the rotor core (20). When viewed in a plane from the first direction (D1), in the second region (R2) of the rotor core (20), each of the multiple permanent magnets (30) has a first surface (31) in contact with the inner surface (21a) of the multiple magnet arrangement holes (21) of the rotor core (20).

[0077] According to the rotor (10) of the above aspect, it is easy to arrange multiple permanent magnets (30) in each of the first region (R1) and the second region (R2), making it possible to easily reduce cogging torque.

[0078] In the rotor (10) according to the third aspect, in the first or second aspect, the plurality of magnet arrangement holes (21) are arranged evenly in the circumferential direction (D2) of the rotating shaft (40).

[0079] According to the rotor (10) of the above aspect, it is not necessary to unevenly arrange the multiple magnet arrangement holes (21) in order to arrange the multiple permanent magnets (30) in a configuration that is not rotationally symmetrical about the rotation center (A1) of the rotor (10). Therefore, the shape of the rotor core (20) can be made rotationally symmetric or nearly so about the rotation center (A1) of the rotor (10), thereby reducing cogging torque.

[0080] In the rotor (10) according to the fourth aspect, in any of the first to third aspects, when viewed in a plan view from the first direction (D1), each of the plurality of permanent magnets (30) has a longitudinal direction that is the radial direction of the rotation shaft (40).

[0081] According to the rotor (10) of the above aspect, the effective area of ​​the permanent magnet (30) is large, so that the magnetic flux can be made denser, thereby improving the torque of the rotor (10).

[0082] In a rotor (10) according to a fifth aspect, in any one of the first to fourth aspects, the rotor core (20) includes a plurality of metal plates (23) stacked in a first direction (D1).

[0083] According to the rotor (10) of the above aspect, it is possible to reduce iron loss due to eddy currents generated in the rotor core (20).

[0084] In a rotor (10) according to a sixth aspect, in the fifth aspect, each of the plurality of metal plates (23) is formed by rolling. The plurality of metal plates (23) includes a first metal plate (23 a) and a second metal plate (23 b). In a plan view from a first direction (D1), a rolling direction (D3) of the first metal plate (23 a) and a rolling direction (D4) of the second metal plate (23 b) intersect.

[0085] According to the rotor (10) of the above aspect, the uniformity of the magnetic properties of the rotor core (20) is increased, and it is possible to further reduce the cogging torque.

[0086] A rotor (10) according to a seventh aspect is the rotor (10) of any one of the first to sixth aspects, wherein the plurality of permanent magnets (30) contain a rare earth.

[0087] According to the rotor (10) of the above aspect, it is possible to increase the density of the magnetic flux of the permanent magnet (30), thereby reducing the cogging torque of the rotor (10) and improving the torque.

[0088] A motor (1) according to an eighth aspect includes the rotor (10) according to any one of the first to seventh aspects and a stator (2). The stator (2) is arranged around a rotor core (20). The stator (2) includes a plurality of coils (69). The difference between the number of the plurality of coils (69) and the number of the plurality of permanent magnets (30) is two or more.

[0089] According to the motor (1) of the above aspect, it is possible to reduce the cogging torque.

[0090] A manufacturing method for a rotor (10) according to a ninth aspect is a manufacturing method for a rotor (10) including a rotating shaft (40), a rotor core (20), and a plurality of permanent magnets (30). The manufacturing method for the rotor (10) includes a first step, a second step, and a third step. In the first step, a rotor core (20) is prepared, the rotor core (20) having an axial hole (100) corresponding to the rotating shaft (40) and a plurality of magnet arrangement holes (21) corresponding one-to-one to the plurality of permanent magnets (30). In a second step, a first magnet (34 a) and a second magnet (35 a) of the plurality of permanent magnets (30) are inserted into two of the plurality of magnet arrangement holes (21) that are adjacent to each other in the circumferential direction (D2) of the rotation shaft (40) so that the first magnetic pole (33 b) of the first magnet (34 a) and the second magnetic pole (33 b) of the second magnet (35 a), which has the same magnetic pole as the first magnetic pole (33 b), face each other in the circumferential direction (D2) of the rotation shaft (40). In a third step, the plurality of permanent magnets (30) are inserted into each of the first region (R1) and the second region (R2) so that two of the plurality of permanent magnets (30) that are adjacent in the circumferential direction (D2) of the rotation shaft (40) face each other in the circumferential direction (D2) of the rotation shaft (40). The first region (R1) and the second region (R2) are partitioned by a virtual plane (P1) that passes through the shaft hole (100) and the space between the first magnet (34a) and the second magnet (35a). In a third step, in the first region (R1), multiple permanent magnets (30) are inserted into the multiple magnet arrangement holes (21) in order, starting with the magnet arrangement hole (21) closest to the first magnet (34a) in the circumferential direction (D2) of the rotation shaft (40). The first region (R1) includes the first magnet (34a). In the third step, in the second region (R2), multiple permanent magnets (30) are inserted into the multiple magnet arrangement holes (21) in order, starting with the magnet arrangement hole (21) closest to the second magnet (35a) in the circumferential direction (D2) of the rotation shaft (40).

[0091] According to the manufacturing method of the rotor (10) relating to the above aspect, it is possible to easily manufacture a rotor (10) in which the arrangement of the multiple permanent magnets (30) is not rotationally symmetrical with respect to the center of rotation (A1) of the rotor (10) by utilizing the repulsive force between the multiple permanent magnets (30).

[0092] REFERENCE SIGNS LIST 1 Motor 2 Stator 10 Rotor 20 Rotor core 21 Magnet arrangement hole 21a Third surface (inner peripheral surface) 21b Fourth surface (inner peripheral surface) 23 Steel plate (metal plate) 23a Steel plate (first metal plate) 23b Steel plate (second metal plate) 30 Permanent magnet 31 First surface 32 Second surface 34a Permanent magnet (first magnet) 35a Permanent magnet (second magnet) 33b Magnetic pole (first magnetic pole, second magnetic pole) 40 Rotating shaft 69 Coil 100 Shaft hole D1 Axial direction (first direction) D2 Circumferential direction D3 Rolling direction D4 Rolling direction R1 First region R2 Second region P1 Virtual plane d2 Width of magnet arrangement hole d4 Width of permanent magnet

Claims

1. A rotor core having an axial hole and a plurality of magnet arrangement holes; a cylindrical rotating shaft arranged in the axial hole of the rotor core; and a plurality of permanent magnets corresponding one-to-one to the plurality of magnet arrangement holes, wherein in a plan view from a first direction which is the axial direction of the rotating shaft, in any one of the plurality of magnet arrangement holes, the width of the one magnet arrangement hole in a second direction perpendicular to the radial direction of the rotating shaft in the one magnet arrangement hole is greater than the width of a permanent magnet in the second direction corresponding to the one of the plurality of permanent magnets, in the one magnet arrangement hole, of the one magnet arrangement hole; in the first region of a first region and a second region of the rotor core defined by an imaginary plane which passes through the axial hole of the rotor core but does not pass through any of the plurality of permanent magnets, in the first region, in the plan view from the first direction, the plurality of permanent magnets are arranged in each of the plurality of magnet arrangement holes with a shift in the clockwise direction of the circumferential direction of the rotating shaft; and in the second region of the rotor core, in the plan view from the first direction, the plurality of permanent magnets are arranged in each of the plurality of magnet arrangement holes with a shift in the counterclockwise direction of the circumferential direction of the rotating shaft. Rotor.

2. The rotor described in claim 1, wherein, when viewed in a plan view from the first direction, each of the multiple permanent magnets has a first face and a second face that face in the circumferential direction of the rotating shaft, each of the multiple permanent magnets is arranged in the order of the first face and the second face in a clockwise direction in the circumferential direction of the rotating shaft, and in the first region of the rotor core, the second face of each of the multiple permanent magnets contacts the inner surfaces of the multiple magnet arrangement holes of the rotor core, and in the second region of the rotor core, the first face of each of the multiple permanent magnets contacts the inner surfaces of the multiple magnet arrangement holes of the rotor core.

3. The rotor according to claim 1, wherein the plurality of magnet arrangement holes are evenly arranged in the circumferential direction of the rotating shaft.

4. The rotor according to claim 1, wherein, in a plan view from the first direction, each of the plurality of permanent magnets has a longitudinal direction that is the radial direction of the rotating shaft.

5. The rotor according to claim 1, wherein the rotor core includes a plurality of metal plates stacked in the first direction.

6. A rotor as described in claim 5, wherein each of the plurality of metal plates is formed by rolling, the plurality of metal plates include a first metal plate and a second metal plate, and when viewed in a plan view from the first direction, a rolling direction of the first metal plate and a rolling direction of the second metal plate intersect with each other.

7. The rotor of claim 1, wherein said plurality of permanent magnets includes rare earth.

8. A motor comprising: a rotor according to claim 1; and a stator arranged around said rotor core, said stator including a plurality of coils, and a difference between the number of said plurality of coils and the number of said plurality of permanent magnets is 2 or more.

9. A method for manufacturing a rotor including a rotating shaft, a rotor core, and a plurality of permanent magnets, comprising: a first step of preparing the rotor core having an axial hole corresponding to the rotating shaft and a plurality of magnet arrangement holes corresponding one-to-one to the plurality of permanent magnets; a second step of inserting a first magnet and a second magnet among the plurality of permanent magnets into each of two magnet arrangement holes that are adjacent to each other in the circumferential direction of the rotating shaft, such that a first magnetic pole of the first magnet and a second magnetic pole of the second magnet, which is the same magnetic pole as the first magnetic pole, face each other in the circumferential direction of the rotating shaft; and a third step of inserting the plurality of permanent magnets into each of a first region and a second region defined by an imaginary plane passing between the first magnet and the second magnet and the axial hole, such that two permanent magnets that are adjacent to each other in the circumferential direction of the rotating shaft face each other with the same magnetic poles in the circumferential direction of the rotating shaft, A method for manufacturing a rotor, comprising: in the first region including the first magnet, inserting the multiple magnets into the multiple magnet arrangement holes in order starting from the magnet arrangement hole closest to the first magnet in the circumferential direction of the rotating shaft; and in the second region, inserting the multiple magnets into the multiple magnet arrangement holes in order starting from the magnet arrangement hole closest to the second magnet in the circumferential direction of the rotating shaft.

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