Rotor, electric motor, blower, air conditioner, and method for manufacturing rotor

Abstract

The present invention provides a rotor including: a first resin magnet which has an outer periphery that extends circumferentially around a central axis and which is magnetized to have a polar anisotropic orientation; and P second resin magnets (where P is an even number) which are provided on the outer periphery of the first resin magnet, which are magnetized to have a polar anisotropic orientation, and which have stronger magnetic poles than the first resin magnet. The distance D1 from the central axis to the outer periphery of the first resin magnet and the distance D2 from the central axis to the outer periphery of each of the plurality of second resin magnets satisfy D1 < D2. The first resin magnet is formed so as to cover at least one end surface of each second resin magnet in the axial direction.

Description

Rotor, electric motor, blower, air conditioner, and method of manufacturing rotor

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

[0002] Regarding the rotor of an electric motor, a rotor having two types of resin magnets, i.e., bonded magnets, with different magnetic properties is known. For example, the rotor disclosed in Patent Document 1 has an annular ferrite bonded magnet and a plurality of rare earth bonded magnets attached to the outer periphery of the annular ferrite bonded magnet.

[0003] In the rotor manufacturing process described above, an annular ferrite bonded magnet is formed, and then a rare earth bonded magnet is embedded in the outer periphery of the ferrite bonded magnet.

[0004] JP 2007-208104 A (see abstract)

[0005] However, in the rotor described above, there is a possibility that the rare earth bonded magnets may fall off from the ferrite bonded magnets.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to prevent the second resin magnet from falling off in a rotor having a ring-shaped first resin magnet and a second resin magnet arranged on its outer periphery.

[0007] The rotor of the present disclosure includes a first resin magnet having an outer periphery extending circumferentially about a central axis and magnetized to have polar anisotropic orientation, and P (P is an even number) second resin magnets disposed on the outer periphery of the first resin magnet, magnetized to have polar anisotropic orientation, and having stronger magnetic poles than the first resin magnet. The distance D1 from the central axis to the outer periphery of the first resin magnet and the distance D2 from the central axis to the outer periphery of each of the P second resin magnets satisfy D1 < D2. The first resin magnet is formed to cover at least one end face of each second resin magnet in the axial direction of the central axis.

[0008] According to the present disclosure, because the first resin magnet covers at least one axial end of the second resin magnet, the integrity of the first and second resin magnets is improved, preventing the second resin magnet from falling off. Furthermore, because D1 < D2 holds, even if a burr occurs at the boundary between the first and second resin magnets, the burr does not protrude from the outer periphery of the rotor, thereby preventing the burr from falling off.

[0009] 4A is a cross-sectional view showing a main portion of the electric motor of embodiment 1. FIG. 4B is a partial cross-sectional view of the electric motor shown in FIG. 1A. FIG. 4B is a partial longitudinal cross-sectional view showing the entire electric motor of embodiment 1. FIG. 4A is a plan view showing the rotor of embodiment 1. FIG. 4B is a side view showing the rotor of embodiment 1. FIG. 4A is a cross-sectional view taken along line 4A-4A shown in FIG. 3B. FIG. 4B is a cross-sectional view taken along line 4B-4B shown in FIG. 4A. FIG. 4B is a plan view showing an enlarged view of the first resin magnet and the second resin magnet of embodiment 1. FIG. 4A is a diagram showing the flow of magnetic flux in the electric motor of embodiment 1. FIG. 4B is a diagram showing the flow of magnetic flux in the rotor of embodiment 1. FIG. 4B is a flowchart showing a method for manufacturing the rotor of embodiment 1. FIG. 4C is a schematic diagram showing a second mold used to mold the second resin magnet of embodiment 1. FIG. 4D is a schematic diagram showing a first mold used to mold the first resin magnet of embodiment 1. 12A is a schematic diagram showing the state in which a second resin magnet is placed in the first mold of FIG. 9 . (B) is a schematic diagram showing the state in which the raw material of the first resin magnet is filled in the first mold. (A) is a cross-sectional view showing the rotor magnet of Comparative Example 1. (A) is a cross-sectional view showing the rotor of Comparative Example 2. (B) is a cross-sectional view taken along line 12B-12B in FIG. 12A . (C) is a schematic diagram showing the state in which the raw material of the second resin magnet is filled in the second mold. (A) is a plan view showing the rotor of embodiment 2. (B) is a cross-sectional view taken along line 13B-13B in FIG. 13A . (A) is a schematic diagram showing the state in which a second resin magnet is placed in the first mold of embodiment 2. (A) is a plan view showing the rotor of embodiment 3. (B) is a cross-sectional view taken along line 15B-15B in FIG. 15A . 18(A) is a schematic diagram showing the state in which a second resin magnet is placed in a first mold according to embodiment 3. FIG. 18(B) is a perspective view showing a second resin magnet unit according to embodiment 4. FIG. 18(A) is a cross-sectional view showing a rotor according to embodiment 4. FIG. 18(B) is a cross-sectional view taken along line 18B-18B shown in FIG. 18(A). FIG. 18(B) is a schematic diagram showing the molding state of a first resin magnet according to embodiment 4 in a first mold. FIG. 18(A) is a perspective view showing a second resin magnet unit according to a modified example of embodiment 4. FIG. 18(A) is a plan view showing a rotor magnet according to a modified example of embodiment 4.23(B) is a cross-sectional view taken along line 21B-21B in FIG. 21(A). A schematic diagram showing the operation of placing a second resin magnet according to a modified example of the fourth embodiment in a first mold. A plan view showing a rotor according to the fifth embodiment. A side view showing a rotor according to the fourth embodiment. A cross-sectional view taken along line 24A-24A in FIG. 23(B). A cross-sectional view taken along line 24B-24B in FIG. 24(A). A schematic diagram showing the state in which a second resin magnet has been placed in a first mold according to the fifth embodiment. A plan view showing a rotor according to the sixth embodiment. A side view showing a rotor according to the fifth embodiment. A cross-sectional view taken along line 27A-27A in FIG. 26(B). A cross-sectional view taken along line 27B-27B in FIG. 27(A). A plan view showing a rotor according to the seventh embodiment. (B) is a side view showing a rotor of embodiment 6. (A) is a cross-sectional view taken along line 29A-29A in FIG. 28(A). (B) and (C) are cross-sectional views showing other configuration examples of embodiment 7. (A) to (F) are schematic diagrams showing examples of the outer peripheral shape of a first resin magnet. A diagram showing a blower of embodiment 8. A diagram showing an air conditioning apparatus of embodiment 9.

[0010] <First Embodiment> <Configuration of electric motor 100> Fig. 1(A) is a cross-sectional view showing a main part of an electric motor 100 according to a first embodiment. Fig. 1(B) is a partial cross-sectional view showing a main part of the electric motor 100. Fig. 2 is a partial vertical cross-sectional view showing the entire electric motor 100. The electric motor 100 is, for example, a permanent magnet synchronous motor.

[0011] As shown in Figures 1A and 1B, the electric motor 100 has a rotor 1 and a stator 5. The rotor 1 is disposed inside the annular stator 5. In other words, the electric motor 100 is an inner rotor type electric motor. An air gap G is formed between the rotor 1 and the stator 5. The air gap G is, for example, a gap of 0.5 mm. Note that Figure 1B shows the stator 5 in cross section, out of the rotor 1 and the stator 5.

[0012] The rotor 1 has a shaft 11 as a rotation axis. The central axis of the shaft 11, which defines the center of rotation of the rotor 1, is referred to as the central axis Ax. The direction of the central axis Ax is referred to as the "axial direction." The direction along the circumference of a circle centered on the central axis Ax is referred to as the "circumferential direction," and the radial direction of the circle centered on the central axis Ax is referred to as the "radial direction."

[0013] The stator 5 includes a stator core 51, a coil 52, an insulator 53 (FIG. 2), and a molded resin portion 55 (FIG. 2).

[0014] The stator core 51 has an annular yoke 51a centered on the central axis Ax and a plurality of teeth 51b extending radially inward from the yoke 51a. The teeth 51b are arranged at equal intervals in the circumferential direction. The teeth 51b face the outer periphery of the rotor 1 via an air gap G. In the example shown in FIG. 1A, the number of teeth 51b is nine, but is not limited to nine and may be two or more.

[0015] The coil 52 is wound around the teeth 51b of the stator core 51. The coil 52 is made of copper wire or aluminum wire. The insulator 53 shown in FIG. 2 is made of resin and electrically insulates the stator core 51 and the coil 52.

[0016] 2, the molded resin part 55 covers the stator core 51, the coils 52, and the insulator 53. An opening is formed on one axial side (the left side in the figure) of the molded resin part 55, and a bottom is formed on the other axial side (the right side in the figure).

[0017] A bracket 14 is attached to the opening of the molded resin part 55, and a bearing 12 is held by the bracket 14. A bearing 13 is held at the bottom of the molded resin part 55. The bearings 12 and 13 are coaxial with each other and support a shaft 11. The shaft 11 protrudes axially from the opening of the molded resin part 55.

[0018] 2, the electric motor 100 further includes a circuit board 60 on one axial side of the rotor 1 and the stator 5. The circuit board 60 is covered with a molded resin part 55. A drive circuit 61 and the like are mounted on the circuit board 60. A magnetic sensor 62 that detects the rotational position of the rotor 1 may also be mounted on the rotor 1 side of the circuit board 60, which will be described later (FIG. 26(B)).

[0019] It should be noted that the electric motor 100 does not necessarily have to include the circuit board 60. Furthermore, the electric motor 100 is not limited to one in which the stator core 51 and the like are covered with the molded resin part 55. For example, the stator core 51 may be fitted inside a cylindrical frame.

[0020] <Configuration of rotor 1> Next, the configuration of the rotor 1 will be described. Fig. 3(A) is a plan view showing the rotor 1. Fig. 3(B) is a side view showing the rotor 1. Fig. 4(A) is a cross-sectional view of the rotor 1 taken along line 4A-4A shown in Fig. 3(B). Fig. 4(B) is a cross-sectional view of the rotor 1 taken along line 4B-4B shown in Fig. 4(A).

[0021] As shown in Fig. 4(A), the rotor 1 has a shaft 11 and an annular rotor magnet 10 supported by the shaft 11. The rotor magnet 10 has a first resin magnet 20 and a plurality of second resin magnets 30. The first resin magnet 20 is formed in an annular shape centered on the central axis Ax. The second resin magnets 30 are arranged around the outer periphery of the first resin magnet 20 at intervals in the circumferential direction.

[0022] The number of second resin magnets 30 is represented as P (P is an even number). The number of second resin magnets 30 is the same as the number of poles of the rotor 1. The first resin magnets 20 are, for example, ferrite bonded magnets and are also referred to as first magnets. The second resin magnets 30 are, for example, rare earth bonded magnets and are also referred to as second magnets.

[0023] The first resin magnet 20 is supported on the shaft 11 via a retaining portion 40 made of resin. The retaining portion 40 is made of a thermosetting resin such as unsaturated polyester resin. The retaining portion 40 may also be made of a thermoplastic resin such as PBT (polybutylene terephthalate).

[0024] The retaining portion 40 has an inner cylindrical portion 41, an outer cylindrical portion 43, and a plurality of ribs 42. The inner cylindrical portion 41 is cylindrical and is fixed to the outer periphery of the shaft 11. The outer cylindrical portion 43 is annular and is fixed to the inner periphery 23 of the first resin magnet 20. The ribs 42 extend radially from the inner cylindrical portion 41 and connect the inner cylindrical portion 41 and the outer cylindrical portion 43. A hollow portion is formed between adjacent ribs 42 in the circumferential direction. The number of ribs 42 is, for example, five, but is not limited to five.

[0025] Here, an example will be described in which the first resin magnet 20 and the shaft 11 are connected by the holding portion 40, but the first resin magnet 20 and the shaft 11 may be directly fixed together without providing the holding portion 40. In this case, the shaft 11 is joined to the inner periphery 23 of the first resin magnet 20.

[0026] <Configuration of First Resin Magnet 20> First resin magnet 20 includes a ferrite magnet and a resin. The resin included in first resin magnet 20 is, for example, at least one of nylon, PPS (polyphenylene sulfide), and epoxy resin.

[0027] The first resin magnet 20 is magnetized to have a polar anisotropic orientation, so that N and S poles are formed alternately in the circumferential direction on the outer periphery 22 of the first resin magnet 20.

[0028] The first resin magnet 20 has an outer periphery 22 extending in the circumferential direction, and a plurality of grooves 21 are formed in this outer periphery 22. The grooves 21 are spaced apart in the circumferential direction, more specifically, arranged at equal intervals. The grooves 21 are formed at positions corresponding to the north poles and at positions corresponding to the south poles. The number of grooves 21 is the same as the number of poles of the rotor 1, i.e., P. A second resin magnet 30 is disposed in each groove 21.

[0029] Figure 5 is an enlarged view of the first resin magnet 20 and the second resin magnet 30 of the rotor 1. Each groove 21 of the first resin magnet 20 has a bottom surface 21a and two side surfaces 21b. The bottom surface 21a of the groove 21 faces radially outward. In the example shown in Figure 5, the bottom surface 21a is curved, for example in an arc shape, so that it is convex radially inward.

[0030] The two side surfaces 21b of the groove 21 extend radially outward from both widthwise ends of the bottom surface 21a. In the example shown in Figure 5, the two side surfaces 21b of the groove 21 extend so that the distance between them becomes narrower as they move radially outward. In the first resin magnet 20, the portion between the circumferentially adjacent N-pole groove 21 and S-pole groove 21 forms the inter-pole portion of the rotor 1. In the inter-pole portion of the rotor 1, the outer periphery 22 of the first resin magnet 20 forms the outer periphery of the rotor 1.

[0031] <Configuration of Second Resin Magnet 30> The second resin magnet 30 includes a rare earth magnet and a resin. The rare earth magnet is, for example, a neodymium magnet containing neodymium (Nd), iron (Fe), and boron (B), or a samarium-iron-nitrogen magnet containing samarium (Sm), Fe, and nitrogen (N). The resin included in the second resin magnet 30 is, for example, the same as the resin included in the first resin magnet 20. In other words, the resin included in the second resin magnet 30 is, for example, at least one of nylon, PPS, and epoxy resin.

[0032] The magnetic pole strength (i.e., magnetic quantity) of the second resin magnet 30 is greater than the magnetic pole strength of the first resin magnet 20. In other words, the magnetic force of the second resin magnet 30 is greater than the magnetic force of the first resin magnet 20. In this way, the second resin magnet 30 is formed from a different material than the first resin magnet 20, and has different magnetic properties.

[0033] The second resin magnet 30 is disposed in the groove 21 of the first resin magnet 20. The first resin magnet 20 and the second resin magnet 30 are integrally molded (also called "two-color molding"), whereby the second resin magnet 30 is joined to the groove 21 of the first resin magnet 20.

[0034] As shown in Figure 5, the second resin magnet 30 has an inner periphery 31 facing radially inward, an outer periphery 32 facing radially outward, and side edges 33 on both sides in the circumferential direction. In the example shown in Figure 5, the inner periphery 31 of the second resin magnet 30 is a curved surface that convex radially inward. Furthermore, the outer periphery 32 of the second resin magnet 30 is a curved surface that convex radially outward.

[0035] An inner periphery 31 of the second resin magnet 30 is bonded to the bottom surface 21 a of the groove 21 of the first resin magnet 20. An outer periphery 32 of the second resin magnet 30 forms part of the outer periphery of the rotor 1. A side end 33 of the second resin magnet 30 is bonded to a side surface 21 b of the groove 21 of the first resin magnet 20.

[0036] The second resin magnets 30 are magnetized to have a polar anisotropic orientation. Circumferentially adjacent second resin magnets 30 have magnetic poles with opposite polarities. The second resin magnets 30 form the pole centers of the magnetic poles.

[0037] The distance from the central axis Ax to the outer periphery 22 of the first resin magnet 20 (more specifically, the outer periphery 22 in the inter-pole portion) is defined as D1. The distance from the central axis Ax to the outer periphery 32 of the second resin magnet 30 is defined as D2. The distances D1 and D2 satisfy the relationship D1 < D2. In other words, the outer periphery 32 of the second resin magnet 30 protrudes radially outward beyond the outer periphery 22 of the first resin magnet 20.

[0038] As described below, the first resin magnet 20 and the second resin magnet 30 are integrally molded by placing the pre-molded second resin magnet 30 in a mold and then filling the mold with the raw material of the first resin magnet 20.

[0039] 3(A) and 3(B), the first resin magnet 20 is formed so as to cover one axial end face of each second resin magnet 30. In other words, the first resin magnet 20 has an end face portion 25 that covers one axial end face of each second resin magnet 30.

[0040] The end surface portion 25 is formed in an annular shape. The distance from the central axis Ax to the outer periphery 25a of the end surface portion 25 is defined as D3. The outer periphery 25a is circumferentially shaped about the central axis Ax, and the distance D3 is constant regardless of the circumferential position. However, the distance D3 may be different between the inter-pole portion and the magnetic pole portion (i.e., the north pole or south pole) (see FIG. 23A, which will be described later).

[0041] The distance D3 from the central axis Ax to the outer periphery 25a of the end surface portion 25 is shorter than the distance D2 from the central axis Ax to the outer periphery 32 of the second resin magnet 30. In other words, D3 < D2 holds. Therefore, the end surface portion 25 does not protrude radially outward beyond the first resin magnet 20.

[0042] Furthermore, the distance D3 from the central axis Ax to the outer periphery 25a of the end surface portion 25 is equal to the distance D1 (FIG. 5) from the central axis Ax to the outer periphery 22 of the first resin magnet 20. In other words, D3 = D1. However, the distances D1 and D3 may be different (FIGS. 30(C) and (D) described later).

[0043] Fig. 6(A) is a schematic diagram showing the flow of magnetic flux in the electric motor 100. Fig. 6(B) is a schematic diagram showing the flow of magnetic flux in the rotor 1. As shown in Fig. 6(A), magnetic flux emerging from the inner periphery of the S-pole second resin magnet 30 passes through the inside of the first resin magnet 20 as shown by the arrows and flows into the inner periphery of the adjacent N-pole second resin magnet 30. Magnetic flux emerging from the outer periphery of the N-pole second resin magnet 30 flows into the teeth 51b of the stator 5 and interlinks with the coils 52.

[0044] 6(B), in the end surface portion 25 of the first resin magnet 20, magnetic flux also flows as shown by the arrows from the portion of the S pole located on the second resin magnet 30 to the portion of the N pole located on the second resin magnet 30. In other words, the end surface portion 25 functions as a magnetic path, just like the other portions of the first resin magnet 20.

[0045] <Method of Manufacturing Rotor 1> Next, a description will be given of a method of manufacturing the rotor 1. Fig. 7 is a flowchart showing the method of manufacturing the rotor 1. Here, the first resin magnet 20 and the second resin magnet 30 are insert-molded by injection molding.

[0046] More specifically, first, the second resin magnet 30 is molded using the second mold 70, and then the second resin magnet 30 is placed in the first mold 80 to mold the first resin magnet 20. In addition to the first mold 80 and the second mold 70, an orientation magnet and a magnetizer are also used.

[0047] In step S1, the raw material of second resin magnet 30 is filled into second mold 70 for molding second resin magnet 30.

[0048] Figure 8 is a cross-sectional view showing the second mold 70. The second mold 70 has an inner mold 71 and an outer mold 72, both of which are cylindrical. A groove 71a is formed on the outer periphery of the inner mold 71, the groove 71a having the same shape as the groove 21 (Figure 5) of the first resin magnet 20 described above. A cavity 71h is formed between the groove 71a of the inner mold 71 and the inner periphery 72a of the outer mold 72.

[0049] The raw material of the second resin magnet 30 is filled into the inside of the groove 71a of the inner mold 71, that is, the above-mentioned cavity 71h, through a gate not shown.

[0050] In step S2, the second resin magnet 30 is molded while being oriented. In step S2, for example, an orientation magnet is used to generate a magnetic field with polar anisotropy inside the second mold 70, and P second resin magnets 30 are molded while orienting the raw material of the second resin magnet 30.

[0051] In step S3, the molded second resin magnet 30 is cooled.

[0052] In step S4, the second resin magnet 30 is removed from the second mold 70.

[0053] In step S5, the removed second resin magnet 30 is demagnetized. The reason for demagnetizing is to prevent the second resin magnet 30 from being attracted to surrounding members in the next step S6 and the like.

[0054] By performing the above steps S1 to S5, P second resin magnets 30 are obtained. It is not necessary to mold P second resin magnets 30 at once; for example, they may be molded one by one. Furthermore, other molding methods such as press molding may be used instead of injection molding.

[0055] In step S6, P second resin magnets 30 are placed inside a first mold 80 for molding the first resin magnet 20.

[0056] 9 is a vertical cross-sectional view showing the state in which the second resin magnet 30 is placed in the first mold 80. The first mold 80 has a lower mold 81 as a fixed mold and an upper mold 82 as a movable mold.

[0057] The lower mold 81 has a cavity H, which is a molding space, and the cavity H is opened and closed by the movement of the upper mold 82. A sprue 86a is formed in the center of the upper mold 82 and opens at the upper end of the upper mold 82. The lower mold 81 has a plurality of runners 86b that communicate with the sprue 86a and extend radially, and gates 86c that connect each runner 86b to the cavity H. The sprue 86a, runners 86b, and gates 86c form a resin flow path 86 that supplies molten resin to the cavity H.

[0058] Figure 10(A) is a cross-sectional view taken along line 10A-10A in Figure 9. The lower mold 81 has a cylindrical cavity H, with a columnar core 84 at its center. The inner periphery 81a of the lower mold 81 is formed with protrusions 83 that protrude radially inward. The protrusions 83 are arranged at equal intervals in the circumferential direction, and the number of protrusions 83 is the same as the number of second resin magnets 30. The protrusions 83 are formed so as to be located between two second resin magnets 30 that are adjacent to each other in the circumferential direction.

[0059] 9, upper mold 82 is formed with a step 85a that protrudes from the outer periphery of the top end surface of second resin magnet 30. This step 85a is intended to make distance D3 (FIG. 3A) from central axis Ax to the outer periphery of end face portion 25 smaller than distance D2 (FIG. 3A) from central axis Ax to outer periphery 32 of second resin magnet 30.

[0060] The upper die 82 of the first mold 80 is raised to open the cavity H of the lower die 81, and P second resin magnets 30 are arranged evenly in the circumferential direction. The circumferential positions of the second resin magnets 30 are determined by the protrusions 83 provided on the lower die 81, making it easy to arrange the second resin magnets 30.

[0061] The second resin magnet 30 is arranged so that one axial end face thereof is the upper face and the other axial end face thereof is the lower face. As shown in Figure 9, a space for forming the end face portion 25 is formed above the second resin magnet 30 in the cavity H.

[0062] In step S7, the raw material of first resin magnet 20 is filled into first mold 80. That is, upper mold 82 is lowered to clamp lower mold 81 and upper mold 82 together, and cavity H is filled with the raw material of first resin magnet 20.

[0063] In step S8 (FIG. 7), the raw material of the first resin magnet 20 is oriented while being molded. In step S8, for example, an orienting magnet is used to generate a magnetic field with polar anisotropy inside the first mold 80, and the first resin magnet 20 is molded while oriented. This forms the rotor magnet 10 in which the first resin magnet 20 and P second resin magnets 30 are integrally molded.

[0064] 10(B) is a schematic diagram showing the state of filling of the raw material of the first resin magnet 20 inside the first mold 80. As shown in FIG. 10(B), the second resin magnet 30 is arranged along the inner periphery 81a of the lower mold 81, and the raw material of the first resin magnet 20 is filled on the inner periphery side of the second resin magnet 30.

[0065] Of the raw material of first resin magnet 20 filled into first mold 80, the portion that comes into contact with protrusion 83 becomes outer periphery 22 of first resin magnet 20. Therefore, as shown in Figure 5, a configuration is obtained in which distance D1 from central axis Ax to outer periphery 22 of first resin magnet 20 is shorter than distance D2 from central axis Ax to outer periphery 32 of second resin magnet 30.

[0066] The molding pressure of the raw material of first resin magnet 20 presses second resin magnet 30 toward its outer periphery, and outer periphery 32 of second resin magnet 30 is pressed against inner periphery 81a of lower die 81. This prevents the raw material of first resin magnet 20 from wrapping around to the surface of outer periphery 32 of second resin magnet 30, and prevents the occurrence of burrs (FIG. 12(B)), which will be described later.

[0067] Furthermore, of the raw material of the first resin magnet 20 filled in the cavity H, the raw material filled above the second resin magnet 30 becomes the end surface portion 25 (Figure 3 (A)).

[0068] In step S9, the rotor magnet 10 formed in step S8 is cooled.

[0069] In step S10, the cooled rotor magnet 10 is removed from the first mold 80.

[0070] In step S11, the rotor magnet 10 removed in step S10 is demagnetized. The reason for demagnetizing is to prevent the rotor magnet 10 from being attracted to surrounding members in the next step S12 and the like.

[0071] In step S12, the rotor magnet 10 is connected to the shaft 11, which is the axis of rotation. As an example, the rotor magnet 10 and shaft 11 are placed in a third mold, and a thermosetting resin such as unsaturated polyester resin or a thermoplastic resin such as PBT is filled to form the retaining portion 40. In this way, the rotor magnet 10 is connected to the shaft 11 via the retaining portion 40.

[0072] In step S13, for example, a magnetizer is used to magnetize the rotor magnet 10. As a result, the first resin magnet 20 and the P number of second resin magnets 30 are magnetized so that the magnetic flux shown in Figures 6(A) and 6(B) flows, and the rotor 1 is completed.

[0073] If the rotor 1 does not have a holding portion 40, the shaft 11 may be fixed directly to the rotor magnet 10 in step S12.

[0074] <Operation> Next, the operation of the first embodiment will be described in comparison with the first and second comparative examples.

[0075] Comparative Example 1. Figure 11 is a cross-sectional view showing rotor magnet 10J of a rotor of Comparative Example 1. Rotor magnet 10J of the rotor of Comparative Example 1 has an annular first resin magnet 20J and an annular second resin magnet 30J that covers the outer periphery of first resin magnet 20J. As in embodiment 1, rotor magnet 10J is supported on shaft 11 (Figure 1).

[0076] The second resin magnet 30J of Comparative Example 1 is magnetized so that the magnetization direction at the pole center is radial and the magnetization direction at the inter-pole portion is circumferential, thereby obtaining a sinusoidal magnetic flux density on the surface of the rotor magnet 10J.

[0077] However, since the second resin magnet 30J is formed in an annular shape so as to cover the first resin magnet 20J, a large amount of the second resin magnet 30J is used, which increases the manufacturing cost.

[0078] In contrast, in the rotor 1 of embodiment 1, as shown in Figure 4(A), P second resin magnets 30 are provided on the surface of the first resin magnet 20. Because the second resin magnets 30 are arranged at the pole centers of the rotor magnet 10, a magnetic flux density equivalent to that of comparative example 1 is obtained at the pole centers. Because the second resin magnets 30 are not arranged in the inter-pole portions, the magnetic flux density is reduced, but because the first resin magnets 20 are arranged in the inter-pole portions, this reduction in magnetic flux density can be compensated for.

[0079] This makes it possible to reduce the amount of second resin magnet 30 used while suppressing a decrease in magnetic flux density on the surface of rotor magnet 10. Although rotor magnet 10 uses a greater amount of first resin magnet 20 than rotor magnet 10J of Comparative Example 1, the unit price of the material for second resin magnet 30 is more than 10 times the unit price of the material for first resin magnet 20, so the manufacturing cost of rotor magnet 10 as a whole is significantly lower than that of rotor magnet 10J of Comparative Example 1.

[0080] Comparative Example 2. Figure 12(A) is a cross-sectional view corresponding to Figure 4(A) and shows a rotor 1K of Comparative Example 2. Figure 12(B) is a cross-sectional view taken along line 12B-12B in Figure 12(A). As shown in Figure 12(A), the rotor magnet 10K of the rotor 1K of Comparative Example 2 has, similar to the rotor magnet 10 of the rotor 1 of embodiment 1, an annular first resin magnet 20K and P second resin magnets 30K provided on the outer periphery 22 of the first resin magnet 20K.

[0081] However, in the rotor 1K of Comparative Example 2, as shown in Figure 12(B), the first resin magnet 20K does not cover the axial end face of the second resin magnet 30K. Therefore, the first resin magnet 20K comes into contact with the second resin magnet 30K only on the inner surface of the groove 21.

[0082] A force acts on the rotor 1K due to temperature changes or centrifugal force during rotation, causing the second resin magnet 30K to fall out of the groove 21 of the first resin magnet 20K. If the contact area between the first resin magnet 20K and the second resin magnet 30K is small, it is difficult to prevent the second resin magnet 30K from falling out.

[0083] In contrast, in the rotor 1 of the first embodiment, as shown in Figure 3(B), the first resin magnet 20 has an end surface portion 25 that covers the axial end surface of the second resin magnet 30. Therefore, the first resin magnet 20 contacts the second resin magnet 30 not only at the inner surface of the groove portion 21 but also at the end surface portion 25. Increasing the contact area between the first resin magnet 20 and the second resin magnet 30 in this way makes it possible to prevent the second resin magnet 30 from falling off.

[0084] In addition, in the molding process of rotor 1K of comparison example 2, first resin magnet 20K is molded using a first mold, and then first resin magnet 20K is placed in second mold 91 to mold second resin magnet 30K.

[0085] Fig. 12(C) is a schematic diagram showing the state of filling of the raw material of the second resin magnet 30K inside the second mold 91. As shown in Fig. 12(C), the raw material of the second resin magnet 30K is filled inside the groove portion 21 of the first resin magnet 20K placed inside the second mold 91.

[0086] A molding pressure is applied to the raw material of second resin magnet 30K as shown by the arrows in Figure 12(C). The molding pressure acts to expand the gap between bottom surface 21a of groove 21 of first resin magnet 20K and inner periphery 91a of second mold 91.

[0087] As a result, the raw material of the second resin magnet 30K enters the gap (indicated by the symbol A) between the outer periphery 22 of the first resin magnet 20K and the inner periphery 91a of the second mold 91. The resin that enters the gap A in this way becomes a burr that protrudes from the second resin magnet 30K. If a burr protrudes from the outer periphery of the rotor, there is a possibility that the burr will come into contact with the stator core 51 when the rotor 1K is assembled inside the stator 5, and fall off, falling into the electric motor 100.

[0088] In contrast, in embodiment 1, as shown in Figure 7, after molding the second resin magnet 30, the second resin magnet 30 is placed in a first mold 80 to mold the first resin magnet 20. Therefore, as shown in Figure 10 (B), the molding pressure applied to the raw material of the first resin magnet 20 presses the second resin magnet 30 against the inner periphery 81a of the lower mold 81. Because no gap is created between the second resin magnet 30 and the lower mold 81, the occurrence of burrs can be suppressed.

[0089] 10(B), in the first embodiment, the distance D1 from the central axis Ax to the outer periphery 22 of the first resin magnet 20 is shorter than the distance D2 from the central axis Ax to the outer periphery 32 of the second resin magnet 30, so even if a burr occurs between the first resin magnet 20 and the second resin magnet 30, the burr is unlikely to protrude beyond the outer periphery of the rotor 1. Therefore, when the rotor 1 is assembled into the stator 5, the burr is prevented from coming into contact with the stator 5 and falling into the electric motor 100.

[0090] Here, an example has been described in which the first resin magnet 20 is formed so as to cover one axial end face of the second resin magnet 30, but the first resin magnet 20 may also be formed so as to cover both axial end faces of the second resin magnet 30. In that case, the first resin magnet 20 has an end face portion 25 that covers one axial end face of the second resin magnet 30, as well as an end face portion 26 that covers the other axial end face of the second resin magnet 30 (see Figure 13(B) described below).

[0091] Furthermore, although an example in which the first resin magnet 20 is a ferrite bonded magnet and the second resin magnet 30 is a rare earth bonded magnet has been described here, other combinations are also possible as long as the magnetic force of the second resin magnet 30 is stronger than the magnetic force of the first resin magnet 20.

[0092] Effect of First Embodiment As described above, the rotor 1 of the first embodiment has an annular first resin magnet 20 and P (P is an even number) second resin magnets 30 arranged on the outer periphery 22 of the first resin magnet 20, with the first resin magnet 20 being formed to cover one axial end face of the second resin magnet 30. Furthermore, the distance D1 from the central axis Ax to the outer periphery 22 of the first resin magnet 20 and the distance D2 from the central axis Ax to the outer periphery 32 of the second resin magnet 30 satisfy the relationship D1 < D2. This improves the integrity of the first resin magnet 20 and the second resin magnet 30, preventing the second resin magnet 30 from falling off. Furthermore, because D1 < D2 holds, even if burrs occur at the boundary between the first resin magnet 20 and the second resin magnet 30, the burrs are less likely to protrude from the outer periphery of the rotor 1, thereby preventing the burrs from falling off.

[0093] The rotor 1 is manufactured by the following steps: molding the second resin magnet 30; placing the second resin magnet 30 inside a first mold 80 and filling the first mold 80 with the raw material for the first resin magnet 20 to mold the first resin magnet 20; and magnetizing the first resin magnet 20 and the second resin magnet 30. In the molding step of the first resin magnet 20, the first resin magnet 20 is formed so as to cover at least one axial end face of the second resin magnet 30. When molding the first resin magnet 20, the second resin magnet 30 is pressed against the inner periphery 81 a of the first mold 80 by molding pressure, thereby suppressing the occurrence of burrs and the like. Because the first resin magnet 20 is formed so as to cover at least one axial end face of the second resin magnet 30, the integrity of the first resin magnet 20 and the second resin magnet 30 is improved, and the second resin magnet 30 can be prevented from falling off.

[0094] Second Embodiment Next, a second embodiment will be described. Figure 13(A) is a plan view showing a rotor 1A of the second embodiment. Figure 13(B) is a cross-sectional view taken along line 13B-13B shown in Figure 13(A). The rotor 1A of the second embodiment differs from the rotor 1 of the first embodiment in the shapes of the first resin magnet 20A and the second resin magnet 30A of the rotor magnet 10A.

[0095] 13(B), the first resin magnet 20A has an end surface portion 25 that covers one axial end surface of the second resin magnet 30A, and an end surface portion 26 that covers the other axial end surface of the second resin magnet 30A. The shape and size of the end surface portion 26 are the same as those of the end surface portion 25.

[0096] A protrusion 34a is formed on one axial end face of the second resin magnet 30A, and a protrusion 34b is formed on the other axial end face of the second resin magnet 30A. The protrusions 34a and 34b are, for example, cylindrical members that protrude in the axial direction, but may have other shapes.

[0097] End surface portion 25 covers one axial end face of second resin magnet 30A and surrounds protrusion 34a. End surface portion 26 covers the other axial end face of second resin magnet 30A and surrounds protrusion 34b. This increases the contact area between first resin magnet 20A and second resin magnet 30A, improving the effectiveness of preventing second resin magnet 30A from falling off.

[0098] The amount of protrusion of the convex portion 34a of the second resin magnet 30A is preferably the same as the thickness of the end surface portion 25 of the first resin magnet 20A. Similarly, the amount of protrusion of the convex portion 34b of the second resin magnet 30A is preferably the same as the thickness of the end surface portion 26 of the first resin magnet 20A.

[0099] In the manufacturing process of rotor 1A of embodiment 2, second resin magnet 30A is first molded using a second mold, and then second resin magnet 30A is placed in a first mold to mold first resin magnet 20A. Second resin magnet 30A is molded in the same manner as second resin magnet 30 of embodiment 1, except that convex portions 34a, 34b are formed on both axial end surfaces.

[0100] 14 is a longitudinal cross-sectional view showing a first mold 80A used to mold first resin magnet 20A. Similar to first mold 80 of embodiment 1, first mold 80A has a lower mold 81 and an upper mold 82. A pre-molded second resin magnet 30A is placed in cavity H of lower mold 81. Protrusion 34b of second resin magnet 30A abuts against the bottom of cavity H.

[0101] Upper mold 82 is formed with a step 85a that contacts the outer periphery of the upper surface of second resin magnet 30A. Lower mold 81 is formed with a step 85b that contacts the outer periphery of the lower surface of second resin magnet 30A. Steps 85a, 85b are located radially outward of protrusions 34a, 34b of second resin magnet 30A.

[0102] The convex portion 34b of the second resin magnet 30A abuts the bottom surface of the cavity H, and the upper and lower surfaces of the second resin magnet 30A abut against the step portions 85a, 85b, so that the second resin magnet 30A is supported within the cavity H and the posture of the second resin magnet 30A can be maintained during molding.

[0103] By filling the first mold 80A with the raw material for the first resin magnet 20A, the first resin magnet 20A is molded integrally with P pieces of the second resin magnets 30A, as described in embodiment 1. This results in a rotor magnet 10A in which the first resin magnet 20A and the second resin magnet 30A are molded integrally.

[0104] End surface portion 25 of first resin magnet 20A is formed to cover one axial end face of second resin magnet 30A and surround protrusion 34a, while end surface portion 26 is formed to cover the other axial end face of second resin magnet 30A and surround protrusion 34b.

[0105] The manufacturing method of rotor 1A of embodiment 2 is the same as the manufacturing method of rotor 1 of embodiment 1, except that convex portions 34a, 34b are formed on second resin magnet 30A and end face portions 25, 26 of first resin magnet 20A are formed so as to surround convex portions 34a, 34b.

[0106] Except for the above points, the rotor 1A of the second embodiment is configured similarly to the rotor 1 of the first embodiment.

[0107] As described above, in embodiment 2, the second resin magnet 30A has convex portions 34a, 34b, and the end face portions 25, 26 of the first resin magnet 20A are formed to surround the convex portions 34a, 34b, thereby increasing the contact area between the first resin magnet 20A and the second resin magnet 30A and improving the effect of preventing the second resin magnet 30A from falling off.

[0108] Note that Figures 13(A) to 14 show an example in which the second resin magnet 30A has convex portions 34a, 34b and the first resin magnet 20A has end surface portions 25, 26, but the second resin magnet 30A may have only one of the convex portions 34a, 34b formed thereon, and the end surface portion of the first resin magnet 20A may be formed only on the same side as the convex portion of the second resin magnet 30A.

[0109] Third Embodiment Next, a third embodiment will be described. Figure 15(A) is a plan view showing a rotor 1B of the third embodiment. Figure 15(B) is a cross-sectional view taken along line 15A-15A shown in Figure 15(A). The rotor 1B of the third embodiment differs from the rotor 1 of the first embodiment in the shapes of the first resin magnet 20B and the second resin magnet 30B of the rotor magnet 10B.

[0110] 15(B), first resin magnet 20B has end surface portion 25 that covers one axial end face of second resin magnet 30B, and end surface portion 26 that covers the other axial end face of second resin magnet 30B. End surface portion 25 and end surface portion 26 are as described in embodiment 2.

[0111] Furthermore, a recess 35a is formed on one axial end face of the second resin magnet 30B, and a recess 35b is formed on the other axial end face of the second resin magnet 30B. The recesses 35a and 35b are, for example, holes that are deep in the axial direction and have a circular cross section, but may have other shapes.

[0112] End surface portion 25 covers one axial end face of second resin magnet 30B and fits into recess 35a. End surface portion 26 covers the other axial end face of second resin magnet 30B and fits into recess 35b. This increases the contact area between first resin magnet 20B and second resin magnet 30B, improving the effect of preventing second resin magnet 30B from falling off.

[0113] In the manufacturing process of rotor 1B of embodiment 3, second resin magnet 30B is first molded using a second mold, and then second resin magnet 30B is placed in a first mold to mold first resin magnet 20B. Second resin magnet 30B is molded in the same manner as second resin magnet 30 of embodiment 1, except that recesses 35a, 35b are formed on both axial end surfaces.

[0114] 16 is a vertical cross-sectional view showing a first mold 80B used to mold first resin magnet 20B. Similar to first mold 80 of embodiment 1, first mold 80B has a lower mold 81 and an upper mold 82. A pre-molded second resin magnet 30B is placed in cavity H of lower mold 81.

[0115] The upper mold 82 is formed with a step 85a that abuts against the outer periphery of the upper surface of the second resin magnet 30B. The lower mold 81 is formed with a step 85b that abuts against the outer periphery of the lower surface of the second resin magnet 30B. The step portions 85a, 85b are located radially outward of the recesses 35a, 35b of the second resin magnet 30B. Because the upper and lower surfaces of the second resin magnet 30B abut against the step portions 85a, 85b, the second resin magnet 30B is supported within the cavity H, and the posture of the second resin magnet 30B can be maintained during molding.

[0116] By filling the first mold 80B with the raw material of the first resin magnet 20B, the first resin magnet 20B is molded integrally with P pieces of the second resin magnets 30B, as described in embodiment 1. This results in a rotor magnet 10B in which the first resin magnet 20B and the second resin magnet 30B are molded integrally, as shown in FIG. 15(B).

[0117] End surface portion 25 of second resin magnet 30B covers one axial end face of second resin magnet 30B and fits into recess 35a, while end surface portion 26 covers the other axial end face of second resin magnet 30B and fits into recess 35b.

[0118] The manufacturing method of rotor 1B of embodiment 3 is the same as the manufacturing method of rotor 1 of embodiment 1, except that recesses 35a, 35b are formed in second resin magnet 30B and first resin magnet 20B is formed so as to fit into recesses 35a, 35b.

[0119] Except for the above points, the rotor 1B of the third embodiment is configured similarly to the rotor 1 of the first embodiment.

[0120] As described above, in embodiment 3, the second resin magnet 30B has recesses 35a, 35b, and the end face portions 25, 26 of the first resin magnet 20B are formed to fit into the recesses 35a, 35b, thereby increasing the contact area between the first resin magnet 20B and the second resin magnet 30B and improving the effect of preventing the second resin magnet 30B from falling off.

[0121] Figures 15(A) to 16 show an example in which the second resin magnet 30B has recesses 35a, 35b and the first resin magnet 20B has end surface portions 25, 26, but the second resin magnet 30B may have only one of the recesses 35a, 35b formed, and the end surface portion of the first resin magnet 20B may be formed only on the same side as the recess of the second resin magnet 30B.

[0122] Next, a fourth embodiment will be described. Figure 17 is a perspective view showing the second resin magnet 30C of a rotor 1C of the fourth embodiment. The rotor 1C of the fourth embodiment differs from the rotor 1 of the first embodiment in that P second resin magnets 30C of a rotor magnet 10C are connected by connecting portions 36.

[0123] The connecting portion 36 is formed in a ring shape centered on the central axis Ax. The P second resin magnets 30C and the connecting portion 36 constitute the second resin magnet unit 130. The connecting portion 36 is formed in the axial center of the second resin magnet 30C.

[0124] Fig. 18(A) is a cross-sectional view showing the rotor 1C. Fig. 18(B) is a side view showing the rotor 1C. Fig. 18(A) corresponds to the cross-sectional view taken along line 18A-18A shown in Fig. 18(B).

[0125] 18(B), the first resin magnet 20C has an end surface portion 25 that covers one axial end surface of the second resin magnet 30C, and an end surface portion 26 that covers the other axial end surface. However, the first resin magnet 20C may have only one of the end surface portions 25, 26.

[0126] 18(A), P second resin magnets 30C are connected by annular connecting portions 36. It is not necessary for all second resin magnets 30C of the rotor magnet 10C to be connected by connecting portions 36, as long as at least two second resin magnets 30C are connected by connecting portions 36. In other words, the connecting portions 36 may be arc-shaped.

[0127] The material of the connecting portion 36 is preferably the same as that of the second resin magnet 30C. If the material of the connecting portion 36 is the same as that of the second resin magnet 30C, the magnetic force of the rotor magnet 10C can be increased.

[0128] A hole 36h is formed in the connecting portion 36. The hole 36h is a through-hole that passes through the connecting portion 36 in the axial direction, but it does not necessarily have to be a through-hole, and may be any portion into which the first resin magnet 20C fits, as will be explained next. It is desirable that the hole 36h be provided in the inter-polar portion so as not to overlap with the second resin magnet 30C.

[0129] The first resin magnet 20C is molded integrally with P second resin magnets 30C and so as to surround the connecting portion 36. The first resin magnet 20C also fits into the hole 36h of the connecting portion 36. This further increases the contact area between the first resin magnet 20C and the second resin magnet 30C.

[0130] When molding the first resin magnet 20C, P pre-molded second resin magnets 30C are placed in the cavity H of the first mold 80A shown in Figure 14. Because the P second resin magnets 30C can be handled as the second resin magnet unit 130, the arrangement and positioning of the second resin magnets 30C can be easily performed.

[0131] 19 is a schematic diagram showing the molding state of first resin magnet 20C in first mold 80A (FIG. 14). When molding first resin magnet 20C, the raw material of first resin magnet 20C enters between outer periphery 36a of connecting portion 36 and protrusion 83 of first mold 80A. In other words, a portion of first resin magnet 20C is formed to cover outer periphery 36a of connecting portion 36.

[0132] Therefore, the distance D1 from the central axis Ax to the outer periphery 22 of the first resin magnet 20C and the distance D4 from the central axis Ax to the outer periphery 36a of the connecting portion 36 satisfy D1 > D4.

[0133] The integrity of the first resin magnet 20C and the second resin magnet 30C can be improved by having a portion of the first resin magnet 20C cover the outer periphery 36a of the connecting portion 36. In addition, because the above-mentioned relationship D1 > D4 holds, the portion of the first resin magnet 20C that covers the outer periphery 36a of the connecting portion 36 can be formed to a thickness that does not cause cracking or peeling, thereby improving the reliability of the rotor magnet 10C.

[0134] Furthermore, when molding first resin magnet 20C, a gap is created between connecting portion 36 and protruding portion 83 of first mold 80A, so even if there is variation in the dimensions of connecting portion 36, there is no interference between connecting portion 36 and protruding portion 83. This improves the productivity of rotor 1C.

[0135] 19, it is desirable that the distances D1 and D4 and the distance D2 from the central axis Ax to the outer periphery 32 of the second resin magnet 30C satisfy the relationship D2 > D1 > D4. Because the second resin magnet 30C is located at the outermost radial position, even if burrs occur between the first resin magnet 20C and the second resin magnet 30C, the burrs are unlikely to protrude from the outer periphery of the rotor 1C.

[0136] In addition, the second resin magnet 30C may be formed with at least one of the convex portions 34a, 34b described in the second embodiment, or at least one of the concave portions 35a, 35b described in the third embodiment.

[0137] Except for the above-mentioned points, the rotor 1C of the fourth embodiment is configured similarly to the rotor 1 of the first embodiment.

[0138] As described above, in the rotor 1C of embodiment 4, two or more second resin magnets 30C are connected by the connecting portions 36, and the first resin magnet 20C is formed to surround the connecting portions 36. This improves the integrity of the first resin magnets 20C and the second resin magnets 30C, and enhances the effect of preventing the second resin magnets 30C from falling off. In addition, this simplifies the work of placing and positioning the second resin magnets 30C within the first mold 80, simplifying the manufacturing process of the rotor 1C.

[0139] Furthermore, since the distance D1 from the central axis Ax to the outer periphery 22 of the first resin magnet 20C and the distance D4 from the central axis Ax to the outer periphery 36a of the connecting portion 36 satisfy D1 > D4, a portion of the first resin magnet 20C covers the outer periphery 36a of the connecting portion 36, thereby improving the unity between the first resin magnet 20C and the second resin magnet 30C.

[0140] Furthermore, since the connecting portion 36 has a hole 36h and the first resin magnet 20C fits into the hole 36h, the contact area between the first resin magnet 20C and the second resin magnet 30C is further increased, further improving the unity. Note that the connecting portion 36 may be provided with a protrusion (see protrusion 37h shown in Figure 20) instead of the hole 36h.

[0141] Modification Example: Figure 20 is a perspective view showing second resin magnets 30D of a rotor magnet 10D according to a modification example of embodiment 4. The P second resin magnets 30D of the modification example are connected at one end of each axial direction by connecting portions 37. The P second resin magnets 30D and the connecting portions 37 form a second resin magnet unit 230.

[0142] The shape and material of the connecting portion 37 are the same as those of the connecting portion 36 in embodiment 4. Here, all of the second resin magnets 30D of the rotor magnet 10D are connected by the connecting portion 37, but it is sufficient that at least two of the second resin magnets 30D are connected.

[0143] Fig. 21(A) is a plan view showing a rotor 1D according to a modification of embodiment 4. Fig. 21(B) is a cross-sectional view taken along line 21B-21B shown in Fig. 21(A).

[0144] 21(B), the first resin magnet 20D has an end surface portion 25 that covers one axial end surface of the second resin magnet 30D, and an end surface portion 26 that covers the other axial end surface. However, it may have only one of the end surface portions 25, 26.

[0145] A connecting portion 37 that connects P second resin magnets 30D is provided at one axial end of the rotor magnet 10D. The connecting portion 37 is formed with a protrusion 37h.

[0146] First resin magnet 20D is molded integrally with P second resin magnets 30D and so as to surround connecting portion 37. Furthermore, end surface portion 25 of first resin magnet 20D is formed so as to cover the end face of second resin magnet 30D and surround protrusion portion 37h.

[0147] The improved integration between the first resin magnet 20D and the second resin magnet 30D can enhance the effectiveness of preventing the second resin magnet 30D from falling off. In particular, as shown in Figure 20, one axial end face of the connecting portion 37 and one axial end face of the second resin magnet 30D are on the same plane, so the protrusion 37h can be made large, further enhancing the effectiveness of preventing the magnet from falling off.

[0148] When molding the first resin magnet 20D, P second resin magnets 30D are placed in the lower mold 81 of the first mold 80D, as shown in Figure 22. Because the P second resin magnets 30D can be handled as the second resin magnet unit 230, the work of placing and positioning the second resin magnets 30D can be easily performed.

[0149] In particular, since the connecting portion 37 is formed at one axial end of the second resin magnet 30D, the second resin magnet unit 230 can be inserted into the first mold 80D from the connecting portion 37 side as shown in Figure 22.

[0150] If the connecting portion 37 were provided in the axial center of the second resin magnet 30D, when the second resin magnet 30D is inserted into the first mold 80D, the end of the second resin magnet 30D in the insertion direction would be displaced radially outward due to the orienting magnetic field, potentially interfering with the protrusion 83 ( FIG. 19 ) of the lower mold 81. In this modified example, the connecting portion 37 is provided at one axial end of the second resin magnet 30D, and therefore interference with the protrusion 83 can be suppressed by inserting the second resin magnet unit 230 from the connecting portion 37 side. This improves rotor productivity.

[0151] As described above, the first resin magnet 20D is molded integrally with P second resin magnets 30D, and is formed so as to surround the connecting portion 37. This improves the unity between the first resin magnet 20D and the second resin magnet 30D, and can enhance the effect of preventing the second resin magnet 30D from falling off.

[0152] Except for the points mentioned above, the rotor 1D of the modified example of the fourth embodiment is configured similarly to the rotor 1C of the fourth embodiment.

[0153] As described above, in the rotor of the modified example of embodiment 4, a connecting portion 37 is formed at one axial end of the second resin magnet 30D, making it easier to insert the second resin magnet 30D into the first mold 80D and improving the productivity of the rotor.

[0154] Furthermore, since the connecting portion 37 has the protrusion 37h and the first resin magnet 20D surrounds the protrusion 37h, the contact area between the first resin magnet 20D and the second resin magnet 30D is increased, further enhancing the unity. Note that the connecting portion 37 may be provided with a hole (see hole 36h shown in Figure 17) instead of the protrusion 37h.

[0155] In this modification, the connecting portion 37 is provided at one axial end of the second resin magnet 30D, but the connecting portion 37 may be provided on one side of the axial center of the second resin magnet 30D. In this case, too, the second resin magnet unit 230 (FIG. 20) can be inserted into the first mold 80D from the end closest to the connecting portion 37, making the insertion process easier.

[0156] Fifth Embodiment Next, a fifth embodiment will be described. Fig. 23(A) is a plan view showing a rotor 1E according to the fifth embodiment. Fig. 23(B) is a side view showing the rotor 1E. The rotor 1E according to the fifth embodiment differs from the rotor 1 according to the first embodiment in the shape of the first resin magnet 20E of the rotor magnet 10E.

[0157] 23(B), end surface portion 25 of first resin magnet 20E is formed so as to completely cover one axial end face of each second resin magnet 30E. Similarly, end surface portion 26 of first resin magnet 20E is formed so as to completely cover the other axial end face of each second resin magnet 30E.

[0158] 23A, of the outer periphery of the end surface portion 25, the magnetic pole outer periphery 25c located on the second resin magnet 30E is located radially outward of the inter-pole outer periphery 25d located in the inter-pole portion. In other words, the distance D5 from the central axis Ax to the magnetic pole outer periphery 25c of the end surface portion 25 is longer than the distance D6 from the central axis Ax to the inter-pole outer periphery 25d of the end surface portion 25. In other words, the distances D5 and D6 satisfy D5 > D6.

[0159] End surface portion 26 (FIG. 23(B)) of first resin magnet 20E is hidden in FIG. 23(A), but has a planar shape similar to end surface portion 25.

[0160] Fig. 24(A) is a cross-sectional view of the rotor 1E taken along line 24A-24A in Fig. 23(B), and Fig. 24(B) is a cross-sectional view of the rotor 1E taken along line 24B-24B in Fig. 24(A).

[0161] In Figure 24 (A), the distance D1 from the central axis Ax to the outer periphery 22 of the first resin magnet 20E and the distance D2 from the central axis Ax to the outer periphery 32 of the second resin magnet 30E satisfy D1 < D2, as explained with reference to Figure 5 in embodiment 1.

[0162] The distance D1 from the central axis Ax to the outer periphery 22 of the first resin magnet 20E is equal to the distance D6 (FIG. 23(A)) from the central axis Ax to the inter-pole outer peripheries 25d, 26d of the end surface portions 25, 26. In other words, D1 = D6 holds. This is because the outer periphery 22 and the inter-pole outer peripheries 25d, 26d are the parts that faced the protrusions 83 (FIG. 10(B)) of the first mold 80E (FIG. 25) during molding.

[0163] 24(B), the magnetic pole outer peripheries 25c, 26c of the end face portions 25, 26 of the first resin magnet 20E are located at the same radial position as the outer periphery 32 of the second resin magnet 30E. This allows the amount of magnetic flux flowing from the rotor 1E into the stator 5 to be increased.

[0164] 25 is a vertical cross-sectional view showing a first mold 80E used to mold first resin magnet 20E. First mold 80E has a lower mold 81 and an upper mold 82. A pre-molded second resin magnet 30E is placed in cavity H of lower mold 81.

[0165] A step portion 85b is formed in the lower mold 81. The second resin magnet 30E is held by this step portion 85b. However, in the fifth embodiment, it is desirable that the step portion 85b be as small as possible.

[0166] By filling the first mold 80E with the raw material of the first resin magnet 20E, the first resin magnet 20E is molded integrally with P pieces of the second resin magnets 30E, as described in embodiment 1. This results in a rotor magnet 10E in which the first resin magnet 20E and the second resin magnet 30E are molded integrally.

[0167] End surface portion 25 of second resin magnet 30E covers one axial end surface of second resin magnet 30E, and end surface portion 26 covers the other axial end surface of second resin magnet 30E. Note that end surface portion 26 has a recess corresponding to step portion 85b, which is filled with the raw material of first resin magnet 20E in a subsequent process.

[0168] In addition, the second resin magnet 30E may be provided with the convex portions 34a, 34b described in embodiment 2, the concave portions 35a, 35b described in embodiment 3, the connecting portion 36 described in embodiment 4, or the connecting portion 37 described in the modified example.

[0169] Except for the points mentioned above, the rotor 1E of the fifth embodiment is configured similarly to the rotor 1 of the first embodiment.

[0170] As described above, in the rotor 1E of embodiment 5, the end face portions 25, 26 of the first resin magnet 20E completely cover both axial end faces of the second resin magnet 30E, thereby increasing the contact area between the first resin magnet 20E and the second resin magnet 30E and improving their unity, thereby enhancing the effect of preventing the second resin magnet 30E from falling off.

[0171] Furthermore, since the magnetic pole outer peripheries 25c, 26c of the end face portions 25, 26 are at the same radial position as the outer periphery 32 of the second resin magnet 30E, the amount of magnetic flux flowing from the rotor 1E to the stator 5 can be increased, thereby improving motor efficiency.

[0172] Here, an example has been described in which end surface portions 25, 26 are formed on first resin magnet 20E, but it is also possible to form only one of end surface portions 25, 26. Alternatively, end surface portions 25, 26 may be formed on first resin magnet 20E, with one of them completely covering the axial end face of second resin magnet 30E.

[0173] Sixth Embodiment Next, a sixth embodiment will be described. Fig. 26(A) is a plan view showing a rotor 1F according to the sixth embodiment. Fig. 26(B) is a side view showing the rotor 1F. The rotor 1F according to the sixth embodiment differs from the rotor 1 according to the first embodiment in that a position detection magnet 27 is formed integrally with a rotor magnet 10F.

[0174] As shown in Figure 26 (B), the rotor 1F has a rotor magnet 10F having a first resin magnet 20F and P second resin magnets 30F, and a position detection magnet 27 formed at one axial end of the rotor magnet 10F.

[0175] The first resin magnet 20F has an end surface portion 25 that covers one axial end face of the second resin magnet 30F. The position detecting magnet 27 is formed on the end surface portion 25. The position detecting magnet 27 is an annular magnet centered on the central axis Ax.

[0176] The position detecting magnet 27 has a plurality of magnetic poles spaced equally apart in the circumferential direction. The number of poles of the position detecting magnet 27 is the same as the number of poles of the rotor magnet 10F (i.e., P). The magnetization direction of the position detecting magnet 27 is the axial direction.

[0177] Fig. 27(A) is a cross-sectional view of the rotor 1F taken along line 27A-27A in Fig. 26(B), and Fig. 27(B) is a cross-sectional view of the rotor 1F taken along line 27B-27B in Fig. 27(A).

[0178] As shown in FIG. 27(A), the arrangement of the second resin magnet 30F on the outer periphery of the first resin magnet 20F is similar to the arrangement of the second resin magnet 30 described in the first embodiment.

[0179] As shown in Figure 27(B), the position-detecting magnet 27 is provided on one axial side of the first resin magnet 20F. The position-detecting magnet 27 is formed integrally with the first resin magnet 20F. That is, the position-detecting magnet 27 is formed from the same material as the first resin magnet 20F. This allows for effective use of the material (e.g., ferrite resin magnet) that constitutes the first resin magnet 20F.

[0180] The magnetic flux of the first resin magnet 20F and the second resin magnet 30F is directed toward the stator core 51 (FIG. 1) as indicated by arrow F1. In contrast, the magnetic flux of the position detection magnet 27 is directed toward a magnetic sensor 62 (FIG. 26(B)), such as a Hall effect element, provided on the circuit board 60 of the stator 5 as indicated by arrow F2. Note that in FIG. 27(B), the hatching of the first resin magnet 20F and the second resin magnet 30F is omitted to make the magnetic flux easier to understand.

[0181] In FIG. 27B, the position detecting magnet 27 is formed radially inward of the second resin magnet 30F, but it may be formed in a position facing the magnetic sensor 62 on the circuit board 60.

[0182] In the magnetization process of the rotor 1F (step S13 shown in FIG. 7), the rotor magnet 10F is magnetized so that its magnetization direction is in the radial direction, and the position detecting magnet 27 is magnetized so that its magnetization direction is in the axial direction. Because the position detecting magnet 27 is located on one side of the rotor magnet 10F in the axial direction, the magnetic force of the rotor magnet 10F is not reduced when the position detecting magnet 27 is magnetized. In other words, the rotor magnet 10F and the position detecting magnet 27, which have different magnetization directions, can be formed integrally without reducing the magnetic forces of the two magnets.

[0183] Here, the position-detecting magnet 27 is formed on the end surface 25 of the first resin magnet 20F, but the position-detecting magnet 27 may also be formed on the side of the first resin magnet 20F opposite the end surface 25. In other words, it is sufficient that the position-detecting magnet 27 is formed at one end of the first resin magnet 20F in the axial direction.

[0184] The end surface portion 25 shown in Figure 26 (A) has the shape described in embodiment 6 (Figure 23 (A)), but is not limited to this and may have, for example, the shape described in embodiment 1 (Figure 3 (A)).

[0185] In addition, the second resin magnet 30F may be provided with the convex portions 34a, 34b described in embodiment 2, the concave portions 35a, 35b described in embodiment 3, the connecting portion 36 described in embodiment 4, or the connecting portion 37 described in the modified example.

[0186] Except for the points mentioned above, the rotor 1F of the sixth embodiment is configured similarly to the rotor 1 of the first embodiment.

[0187] As described above, in the rotor 1F of embodiment 6, the position detection magnet 27 is formed integrally with the first resin magnet 20F, so that the constituent material of the first resin magnet 20F can be effectively utilized.

[0188] Furthermore, since the position detection magnet 27 is formed on one axial side of the first resin magnet 20F, the rotor magnet 10F and the position detection magnet 27, which have different magnetization directions, can be formed integrally and sufficiently magnetized.

[0189] Seventh Embodiment Next, a seventh embodiment will be described. Fig. 28(A) is a bottom view showing a rotor 1G according to the seventh embodiment. Fig. 28(B) is a side view showing the rotor 1G. The rotor 1G according to the seventh embodiment differs from the rotor 1 according to the first embodiment in that an end face resin portion 45 is formed on a rotor magnet 10G.

[0190] 28(B), the rotor magnet 10G has a rotor magnet 10G that includes a first resin magnet 20G and P second resin magnets 30G, and the first resin magnet 20G has an end face portion 25 that covers one axial end face of the second resin magnet 30G. The rotor 1G also has an end face resin portion 45 as a resin portion that covers the end face opposite to the end face portion 25 of the rotor magnet 10G.

[0191] 28(A), the end surface resin portion 45 is formed integrally with the holding portion 40. As described in the first embodiment, the holding portion 40 is provided between the first resin magnet 20G and the shaft 11 in the radial direction, and has an inner cylindrical portion 41, an outer cylindrical portion 43, and a plurality of ribs 42.

[0192] Figure 29(A) is a cross-sectional view of the rotor 1G taken along line 29A-29A in Figure 28(A). As shown in Figure 29(A), the inner cylinder 41 of the holder 40 is fixed to the outer periphery of the shaft 11. The outer cylinder 43 is fixed to the inner periphery of the first resin magnet 20G. Ribs 42 extend radially from the inner cylinder 41 and connect the inner cylinder 41 and the outer cylinder 43.

[0193] The end surface resin portion 45 is formed continuously with the inner cylinder portion 41, the outer cylinder portion 43, and the rib 42, and is formed in an annular shape so as to cover the axial end face (e.g., the lower end face in the figure) of the first resin magnet 20G and each of the axial end faces of the P second resin magnets 30G. The end surface resin portion 45 is formed from the same material as the retaining portion 40, for example, unsaturated polyester resin.

[0194] Fig. 29(B) is a cross-sectional view corresponding to Fig. 29(A) and shows another example of the configuration of the rotor 1G according to embodiment 7. As shown in Fig. 29(B), the protrusions 34a and 34b described in embodiment 2 may be formed on both axial end surfaces of the second resin magnet 30G.

[0195] In this case, end face portion 25 of first resin magnet 20G is formed to surround convex portion 34a, and end face resin portion 45 is formed to surround convex portion 34b, improving the unity between first resin magnet 20G and second resin magnet 30G. Second resin magnet 30G may be formed with only one of convex portions 34a, 34b, or may be formed with concave portions 35a, 35b as described in embodiment 3.

[0196] Fig. 29(C) is a cross-sectional view corresponding to Fig. 29(A) and shows another example of the configuration of the rotor 1G of embodiment 7. As shown in Fig. 29(C), the position detection magnet 27 described in embodiment 6 may be formed integrally with the first resin magnet 20G.

[0197] 29(A) to 29(C), the end surface resin portion 45 is formed on the side opposite the end surface portion 25 of the rotor magnet 10G, but it may also be formed on the end surface portion 25. The end surface resin portion 45 may also be formed on both axial ends of the rotor magnet 10G. In other words, it is sufficient that the end surface resin portion 45 is formed on at least one axial end of the rotor magnet 10G.

[0198] The second resin magnet 30G may be provided with the connecting portion 36 described in the fourth embodiment or the connecting portion 37 described in the modified example.

[0199] Except for the points mentioned above, the rotor 1G of the seventh embodiment is configured similarly to the rotor 1 of the first embodiment.

[0200] As described above, in the rotor 1G of embodiment 7, an end face resin portion 45 is formed at at least one axial end of the first resin magnet 20G and the second resin magnet 30G, thereby improving the unity between the first resin magnet 20G and the second resin magnet 30G and enhancing the effect of preventing the first resin magnet 20G from falling off.

[0201] <Other Configuration Examples> Next, examples of the outer peripheral shape of the first resin magnet 20 will be described. Figure 30(A) is a cross-sectional view showing an example of the configuration of the rotor 1 of embodiment 1, and corresponds to the cross-sectional view taken along line 4B-4B shown in Figure 4(A). Figure 30(B) is an enlarged plan view showing the outer peripheral portion of the rotor 1 shown in Figure 30(A).

[0202] 30(A) and (B), the distance D3 from the central axis Ax to the outer peripheries 25a, 26a of the end face portions 25, 26 is equal to the distance D1 from the central axis Ax to the outer periphery 22 in the inter-pole portion of the first resin magnet 20. In other words, D1 = D3. In this case, the shape of the first mold 80 (FIG. 9) can be simplified.

[0203] Furthermore, the distances D1 and D3 are equal to or less than the distance D2 from the central axis Ax to the outer periphery 32 of the second resin magnet 30. In other words, D1 = D3 ≦ D2 holds. Therefore, it is possible to prevent the first resin magnet 20 from protruding from the outer periphery of the rotor 1.

[0204] Fig. 30(C) is a cross-sectional view showing another example of the configuration of the rotor 1 according to embodiment 1. Fig. 30(D) is an enlarged plan view showing the outer periphery of the rotor 1 shown in Fig. 30(C).

[0205] 30(C) and (D), the distance D3 from the central axis Ax to the outer peripheries 25a, 26a of the end surface portions 25, 26 is shorter than the distance D1 from the central axis Ax to the outer periphery 22 in the inter-pole portion of the first resin magnet 20. In other words, D3 < D1 holds. In this case, the amount of material used for the end surface portions 25, 26 of the first resin magnet 20 can be reduced.

[0206] Furthermore, distances D1 and D3 are equal to or less than distance D2 from central axis Ax to outer periphery 32 of second resin magnet 30. In other words, D3 < D1 ≦ D2 holds. Therefore, first resin magnet 20 can be prevented from protruding from the outer periphery of rotor 1.

[0207] 30A to 30D, the distance D3 from the central axis Ax to the outer peripheries 25 a, 26 a of the end face portions 25, 26 is constant regardless of the circumferential position. However, the distance D3 from the central axis Ax to the outer peripheries 25 a, 26 a of the end face portions 25, 26 may be different between the magnetic pole portion and the inter-pole portion.

[0208] Fig. 30(E) is a cross-sectional view showing another example of the configuration of the rotor 1 according to embodiment 1. Fig. 30(F) is an enlarged plan view showing the outer periphery of the rotor 1 shown in Fig. 30(E).

[0209] 30(E) and (F), the distance D5 from the central axis Ax to the magnetic pole outer peripheries 25c, 26c of the end face portions 25, 26 is longer than the distance D1 from the central axis Ax to the outer periphery 22 in the inter-pole portion of the first resin magnet 20. In other words, D1 < D5 holds. In this case, the effect of preventing the second resin magnet 30 from falling off can be improved.

[0210] Furthermore, distances D1 and D5 are equal to or less than distance D2 from central axis Ax to outer periphery 32 of second resin magnet 30. In other words, D1 < D5 ≦ D2 holds. Therefore, first resin magnet 20 can be prevented from protruding from the outer periphery of rotor 1.

[0211] The examples of the outer peripheral shape of the first resin magnet 20 shown in Figures 30(A) to (F) can also be applied to the rotors 1A to 1F of embodiments 2 to 7.

[0212] The configurations of the rotors 1 to 1G described in the above-mentioned second to seventh embodiments and the configuration examples described with reference to FIGS. 30(A) to 30(F) can be combined as appropriate.

[0213] Eighth Embodiment Next, a description will be given of the configuration of a blower 400 according to an eighth embodiment. Fig. 31 is a diagram schematically showing the configuration of a blower 400 according to the eighth embodiment.

[0214] As shown in Figure 31, blower 400 has electric motor 100 and impeller 401 driven by electric motor 100. Impeller 401 is attached to shaft 11 (Figure 1) of electric motor 100. When shaft 11 of electric motor 100 rotates, impeller 401 rotates and generates an airflow. Blower 400 is used, for example, as an outdoor blower of outdoor unit 520 of air conditioning apparatus 500 (Figure 32) described below. Impeller 401 is, for example, a propeller fan.

[0215] Since the fan 400 of the eighth embodiment has the electric motor 100 described in the first embodiment, it is possible to improve the reliability of the fan 400 and reduce the manufacturing cost. The same effect can be obtained when the electric motor described in any of the second to seventh embodiments or the electric motor described in the modified examples or configuration examples is used instead of the electric motor 100 described in the first embodiment.

[0216] Ninth Embodiment Next, a description will be given of the configuration of an air conditioning apparatus 500 equipped with a blower 400 according to Embodiment 9. Fig. 32 is a diagram showing the configuration of an air conditioning apparatus 500 according to Embodiment 9.

[0217] 32 , the air conditioning apparatus 500 has an indoor unit 510 and an outdoor unit 520. The indoor unit 510 and the outdoor unit 520 are connected by refrigerant piping 530 and form a refrigerant circuit through which refrigerant circulates. The air conditioning apparatus 500 can perform, for example, cooling operation in which cool air is blown from the indoor unit 510, or heating operation in which warm air is blown.

[0218] The indoor unit 510 has an indoor blower 511 as a blower and a housing 512 that houses the indoor blower 511. The indoor blower 511 has an electric motor 511a and an impeller 511b driven by the electric motor 511a. The impeller 511b is attached to the shaft of the electric motor 511a. Rotation of the shaft of the electric motor 511a rotates the impeller 511b, generating an airflow. The impeller 511b is, for example, a crossflow fan.

[0219] The outdoor unit 520 includes a blower 400 as an outdoor blower, a compressor 521, and a housing 522 that houses these components. The compressor 521 includes a compression mechanism 521a that compresses the refrigerant and an electric motor 521b that drives the compression mechanism 521a. The compression mechanism 521a and the electric motor 521b are connected to each other by a shaft 521c. Note that the electric motor 100 according to the first embodiment may be used as the electric motor 521b of the compressor 521.

[0220] The outdoor unit 520 further includes a four-way valve (not shown) for switching the flow direction of the refrigerant. The four-way valve of the outdoor unit 520 directs the high-temperature, high-pressure refrigerant gas sent from the compressor 521 to the heat exchanger of the outdoor unit 520 during cooling operation, and to the heat exchanger of the indoor unit 510 during heating operation.

[0221] For example, during cooling operation of the air conditioner 500, the heat released when the refrigerant compressed by the compressor 521 of the outdoor unit 520 condenses in a condenser (not shown) is released to the outside by the air blown by the blower 400. Also, the air from which heat has been removed when the refrigerant evaporates in the evaporator (not shown) of the indoor unit 510 is supplied into the room by the indoor blower 511.

[0222] The blower 400 is not limited to being an outdoor blower of the outdoor unit 520, but may also be used as the above-mentioned indoor blower 511. The blower 400 is not limited to being provided in the air conditioning apparatus 500, but may also be provided in other electrical equipment.

[0223] The air conditioning apparatus 500 of the ninth embodiment has the blower 400 described in the eighth embodiment, and therefore can improve reliability and reduce manufacturing costs.

[0224] Although the preferred embodiments have been specifically described above, the present disclosure is not limited to the above-described embodiments, and various improvements and modifications can be made.

[0225] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G Rotor, 5 Stator, 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G Rotor magnet, 11 Shaft, 20, 20A, 20B, 20C, 20D, 20E, 20F, 20G First resin magnet, 21 Groove portion, 22 Outer periphery, 23 Inner periphery, 25 End surface portion, 25a Outer periphery, 25c Magnetic pole periphery, 25d Inter-pole periphery, 26 End surface portion, 26a Outer periphery, 26c Magnetic pole periphery, 26d Inter-pole periphery, 27 Position detection magnet, 30, 30A, 30B, 30C, 30D, 30E, 30F, 30G Second resin magnet, 32 Outer periphery, 34a, 34b: convex portion, 35a, 35b: concave portion, 36: connecting portion, 36h: hole portion, 37: connecting portion, 37h: protrusion portion, 40: holding portion, 41: inner cylinder portion, 42: rib, 43: outer cylinder portion, 45: end face resin portion (resin portion), 50: stator core, 52: coil, 53: insulator, 55: molded resin portion, 60: circuit board, 62: magnetic sensor, 70: second mold, 80, 80A, 80B, 80D, 80E: first mold, 81: lower mold, 82: upper mold, 83: convex portion, 85a, 85b: step portion, 86: resin flow path, 100: electric motor, 400: blower, 401: impeller, 500 Air conditioning device, 510 indoor unit, 511 indoor blower, 520 outdoor unit.

Claims

1. A rotor comprising: a first resin magnet having an outer periphery extending circumferentially around a central axis and magnetized to have polar anisotropic orientation; and P (P is an even number) second resin magnets provided on the outer periphery of the first resin magnet, magnetized to have polar anisotropic orientation, and having stronger magnetic poles than the first resin magnet, wherein a distance D1 from the central axis to the outer periphery of the first resin magnet and a distance D2 from the central axis to the outer periphery of each of the P second resin magnets satisfy D1 < D2, and the first resin magnet is formed so as to cover at least one end face of each second resin magnet in the axial direction of the central axis.

2. The rotor according to claim 1, wherein the second resin magnet has a protrusion on at least one end face in the axial direction.

3. The rotor according to claim 1 or 2, wherein the second resin magnet has a recess on at least one end face in the axial direction.

4. A rotor according to any one of claims 1 to 3, comprising connecting portions that connect at least two of the P second resin magnets that are adjacent to each other in the circumferential direction.

5. The rotor according to claim 4, wherein the connecting portion has a hole or a protrusion, and the first resin magnet is formed so as to enter the hole of the connecting portion or to surround the protrusion.

6. The rotor according to claim 4 or 5, wherein the connecting portion is provided at the center of the second resin magnet in the axial direction.

7. A rotor according to claim 4 or 5, wherein the connecting portion is provided on one end side of the second resin magnet in the axial direction relative to a central portion of the second resin magnet in the axial direction.

8. A rotor as claimed in any one of claims 1 to 7, wherein a distance D1 from the central axis to the outer periphery of the first resin magnet and a distance D3 from the central axis to the outer periphery of the portion of the first resin magnet which covers the second resin magnet satisfy D1 = D3.

9. A rotor as claimed in any one of claims 1 to 8, wherein a distance D1 from the central axis to the outer periphery of the first resin magnet and a distance D3 from the central axis to the outer periphery of a portion of the first resin magnet which covers the second resin magnet satisfy D1 < D3.

10. A rotor described in any one of claims 1 to 9, wherein a distance D1 from the central axis to the outer periphery of the first resin magnet, a distance D2 from the central axis to the outer periphery of the second resin magnet, and a distance D3 from the central axis to the outer periphery of the portion of the first resin magnet covering the second resin magnet satisfy D1≦D3≦D2.

11. A rotor according to any one of claims 1 to 10, wherein the first resin magnet is formed so as to cover both ends of the second resin magnet in the axial direction.

12. A rotor according to any one of claims 1 to 11, wherein a position detection magnet is integrally formed at an end of the first resin magnet in the axial direction.

13. The rotor according to claim 12, wherein the position detection magnet is formed on one side in the axial direction with respect to the first resin magnet.

14. A rotor according to any one of claims 1 to 13, wherein a resin portion is formed so as to cover at least one end face in the axial direction of the first resin magnet and the second resin magnet.

15. The rotor according to claim 14, further comprising a holding portion that connects the first resin magnet to a shaft, the holding portion and the resin portion being integrally formed.

16. An electric motor comprising a rotor according to any one of claims 1 to 15 and a stator surrounding said rotor.

17. A blower comprising: an electric motor according to claim 16; and an impeller driven by said electric motor.

18. An air-conditioning apparatus comprising: an indoor unit; and an outdoor unit connected to the indoor unit, at least one of the indoor unit and the outdoor unit comprising the blower according to claim 17.

19. A method for manufacturing a rotor having a first resin magnet having an outer periphery extending in a circumferential direction centered on a central axis and magnetized to have a polar anisotropic orientation, and P (P is an even number) second resin magnets provided on the outer periphery of the first resin magnet, magnetized to have a polar anisotropic orientation, and having stronger magnetic poles than the first resin magnet, comprising the steps of: molding the P second resin magnets; placing the P second resin magnets inside a mold and filling the mold with raw material for the first resin magnet to mold the first resin magnet; and magnetizing the first resin magnet and the P second resin magnets, wherein in the molding of the first resin magnet, the first resin magnet is molded so as to cover at least one end face in the axial direction of the central axis of each of the P second resin magnets.

20. A rotor manufacturing method as described in claim 19, wherein in the process of molding the first resin magnet, the first resin magnet is molded so that the distance D1 from the central axis to the outer periphery of the first resin magnet and the distance D2 from the central axis to the outer periphery of each second resin magnet satisfy D1 < D2.

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