Electric motor, blower, and air conditioner

Abstract

This electric motor has a shaft, a rotor having a rotor magnet secured to the shaft, and a stator that surrounds the rotor from the outside in the radial direction centered on the shaft. The rotor magnet has: a first magnet that is magnetized to have a polar anisotropic orientation; and P second magnets (where P is an even number) that are arranged around the periphery of the first magnet, magnetized to have the polar anisotropic orientation, and have stronger magnetic poles than the first magnet. The stator has a stator core, and a coil wound around the stator core. A length Hr of rotor magnet in the axial direction of the shaft and an axial-direction length Hs of the stator core satisfy Hr>Hs. The rotor magnet has, in the axial direction, a stator-facing portion that faces the stator core in the radial direction, and an overhang portion that projects from the stator core in the axial direction. The volume ratio of the second magnet to the first magnet is smaller in the overhang portion than in the stator-facing portion.

Description

Technical Field

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

Background Art

[0002] A rotor of an electric motor having two types of permanent magnets with different magnetic characteristics is known. For example, the rotor described in Patent Document 1 has an annular ferrite bonded magnet and an annular rare earth bonded magnet provided on the outer peripheral side thereof.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above rotor improves the magnetic force by combining a ferrite bonded magnet and a rare earth bonded magnet. However, since the rare earth bonded magnet is more expensive than the ferrite bonded magnet, it is difficult to reduce the manufacturing cost in a rotor using an annular rare earth bonded magnet.

[0005] The present disclosure aims to reduce the manufacturing cost of an electric motor.

Means for Solving the Problems

[0006] The motor of the present disclosure includes a rotor having a shaft and a rotor magnet fixed to the shaft, and a stator surrounding the rotor from the radially outer side centered on the shaft. The rotor magnet includes a first magnet magnetized to have a uniaxial anisotropic orientation, and P (P is an even number) second magnets disposed on the outer periphery of the first magnet, magnetized to have a uniaxial anisotropic orientation, and having magnetic poles stronger than those of the first magnet. The stator includes a stator core and a coil wound around the stator core. The axial length Hr of the shaft of the rotor magnet and the axial length Hs of the stator core satisfy Hr > Hs. The rotor magnet has, in the axial direction, a stator facing portion that faces the stator core in the radial direction and an overhang portion that protrudes axially from the stator core. The first magnet has P groove portions provided at equal intervals on the outer periphery of the stator facing portion. The P groove portions are formed so as not to reach the end surface on the side opposite to the stator facing portion of the overhang portion in the axial direction. The P second magnets are respectively disposed in the P groove portions. The volume ratio of the second magnet to the first magnet is smaller in the overhang portion than in the stator facing portion. The motor of the present disclosure also includes a rotor having a shaft and a rotor magnet fixed to the shaft, and a stator surrounding the rotor from the radially outer side around the shaft. The rotor magnet includes a first magnet magnetized to have a magnetic anisotropic orientation, and P (P is an even number) second magnets arranged on the outer periphery of the first magnet, magnetized to have a magnetic anisotropic orientation, and having magnetic poles stronger than those of the first magnet. The stator includes a stator core and a coil wound around the stator core. The axial length Hr of the shaft of the rotor magnet and the axial length Hs of the stator core satisfy Hr > Hs. The rotor magnet has a stator facing portion that faces the stator core in the radial direction and an overhang portion that protrudes axially from the stator core in the axial direction. The first magnet has P groove portions provided at equal intervals on the outer periphery of the stator facing portion. The P second magnets are respectively arranged in the P groove portions. The volume ratio of the second magnet to the first magnet is smaller in the overhang portion than in the stator facing portion. The overhang portion has the first magnet and does not have the second magnet. The motor of the present disclosure also includes a rotor having a shaft and a rotor magnet fixed to the shaft, and a stator surrounding the rotor from the outer side in the radial direction centered on the shaft. The rotor magnet includes a first magnet magnetized to have a pole anisotropic orientation, and P (P is an even number) second magnets arranged on the outer periphery of the first magnet, magnetized to have a pole anisotropic orientation, and having magnetic poles stronger than those of the first magnet. The stator includes a stator core and a coil wound around the stator core. The axial length Hr of the shaft of the rotor magnet and the axial length Hs of the stator core satisfy Hr > Hs. The rotor magnet has a stator facing portion that faces the stator core in the radial direction in the axial direction, and an overhang portion that projects axially from the stator core. The first magnet has P groove portions provided at equal intervals on the outer periphery of the stator facing portion. The P second magnets are respectively arranged in the P groove portions. The volume ratio of the second magnet to the first magnet is smaller in the overhang portion than in the stator facing portion. The distance R1 from the central axis of the shaft to the outer periphery of the stator facing portion and the distance R2 from the central axis to the outer periphery of the overhang portion satisfy R1 < R2.

Advantages of the Invention

[0007] In the present disclosure, since the volume ratio of the second magnet to the first magnet is smaller in the overhang portion than in the stator facing portion, the manufacturing cost can be reduced without reducing the output and efficiency of the motor.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

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Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Mode for Carrying Out the Invention

[0009] 《Embodiment 1》 〈Configuration of the Electric Motor 100〉 FIG. 1(A) is a cross-sectional view showing the main part of the electric motor 100 of Embodiment 1. FIG. 1(B) is a partial cross-sectional view showing the main part of the electric motor 100. FIG. 2 is a partial cross-sectional view showing the whole of the electric motor 100. The electric motor 100 is, for example, a permanent magnet synchronous motor.

[0010] As shown in FIGS. 1(A) and 1(B), the electric motor 100 has a rotor 1 and a stator 6. The rotor 1 is disposed inside the stator 6. That is, the electric motor 100 is an inner rotor type electric motor. An air gap G is formed between the rotor 1 and the stator 6. The air gap G is, for example, a 0.5 mm gap. In FIG. 1(B), among the rotor 1 and the stator 6, the stator 6 is shown in cross section.

[0011] The rotor 1 has a shaft 10 as a rotation axis. The central axis of the shaft 10 that defines the rotation center 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 a circle centered on the central axis Ax is referred to as the "radial direction".

[0012] The stator 6 has a stator core 61, a coil 62, an insulator 63 (Fig. 2), and a molded resin part 64 (Fig. 2).

[0013] The stator core 61 has an annular yoke 61a centered on the central axis Ax and a plurality of teeth 61b extending radially inward from the yoke 61a. The teeth 61b are arranged at equal angular intervals in the circumferential direction. The teeth 61b face the outer circumference 1c of the rotor 1 via an air gap G. In the example shown in Fig. 1(A), the number of teeth 61b is 12, but it is not limited to 12 and may be 2 or more.

[0014] The coil 62 is wound around the teeth 61b of the stator core 61. The coil 62 is composed of a copper wire or an aluminum wire. The insulator 63 shown in Fig. 2 is formed of resin and electrically insulates the stator core 61 and the coil 62.

[0015] The molded resin part 64 covers the stator core 61, the coil 62, and the insulator 63. The rotor 1 is accommodated inside the molded resin part 64, and the shaft 10 protrudes to one side in the axial direction (the left side in the figure). Among the bearings 11 and 12 that support the shaft 10, the bearing 11 is held by a bracket 13 attached to the one side of the molded resin part 64, and the bearing 12 is held on the other side of the molded resin part 64.

[0016] Note that the electric motor 100 is not limited to the one in which the stator core 61 etc. are covered with the molded resin part 64, and it may be the one in which the stator core 61 is fitted inside a cylindrical frame.

[0017] In the example shown in FIG. 2, the electric motor 100 further includes a circuit board 8 on which a magnetic sensor 8a is mounted. The magnetic sensor 8a detects the magnetic field of a sensor magnet (not shown) provided on the rotor 1, thereby detecting the position of the rotor 1 in the circumferential direction. Note that the electric motor 100 can be realized even without the magnetic sensor 8a.

[0018] <Configuration of Rotor 1> Next, the configuration of the rotor 1 will be described. FIG. 3(A) is a side view showing the rotor 1 shown in FIG. 1. In FIG. 3(A), a part of the stator 6 is shown by a broken line. The rotor 1 has P poles. P is an even number of 2 or more, and here it is 8.

[0019] The rotor 1 has a shaft 10 and a rotor magnet 50 fixed to the shaft 10. The rotor magnet 50 has a ferrite bonded magnet 20 and a plurality of rare earth bonded magnets 30. The number of the rare earth bonded magnets 30 is the same as the number of poles P of the rotor 1. The ferrite bonded magnet 20 is also referred to as a first magnet or a first resin magnet. The rare earth bonded magnet 30 is also referred to as a second magnet or a second resin magnet.

[0020] Assuming that the axial length of the rotor magnet 50 is Hr and the axial length of the stator core 61 is Hs, the length Hr is longer than the length Hs (Hr > Hs).

[0021] The rotor magnet 50 protrudes from one side in the axial direction of the stator core 61, for example, the lower side in FIG. 3(A). The rotor magnet 50 has a first end face 50a that is one end face in the axial direction and a second end face 50b that is the other end face in the axial direction.

[0022] The first end face 50a of the rotor magnet 50 is at the same axial position as the first end face 60a that is one end face in the axial direction of the stator core 61. On the other hand, the second end face 50b of the rotor magnet 50 is below the second end face 60b that is the other end face in the axial direction of the stator core 61 in the drawing, that is, on the side away from the first end face 50a.

[0023] Therefore, the rotor magnet 50 has, in the axial direction, a stator facing portion 51 and an overhang portion 52. The stator facing portion 51 faces the stator core 61 with an air gap therebetween. The overhang portion 52 protrudes axially from the stator core 61.

[0024] FIG. 3(B) is a cross-sectional view taken along line segment 3B-3B shown in FIG. 3(A), that is, a cross-sectional view of the rotor 1 on a plane passing through the stator facing portion 51. As shown in FIG. 3(B), the ferrite bonded magnet 20 is supported by the shaft 10 via a resin portion 40 as a holding portion. The resin portion 40 is formed of a thermoplastic resin such as, for example, PBT (polybutylene terephthalate). The resin portion 40 has an inner cylinder portion 41, an outer cylinder portion 42, and a plurality of ribs 43. The number of ribs 43 is, for example, four, but is not limited thereto.

[0025] The inner cylinder portion 41 is cylindrical and is fixed to the outer periphery of the shaft 10. The outer cylinder portion 42 is cylindrical and is fixed to the inner periphery of the annular ferrite bonded magnet 20. The ribs 43 connect the inner cylinder portion 41 and the outer cylinder portion 42. The ribs 43 extend radially outward from the outer periphery of the inner cylinder portion 41. Note that the ferrite bonded magnet 20 may be directly fixed to the shaft 10 without providing the resin portion 40.

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

[0027] Of the ferrite bonded magnet 20, the portion included in the stator facing portion 51 is referred to as a first portion 21, and the portion included in the overhang portion 52 is referred to as a second portion 22.

[0028] As shown in Fig. 3(B), the ferrite bonded magnet 20 is formed in an annular shape centered on the central axis Ax. The outer periphery 20c of the ferrite bonded magnet 20 forms a part of the outer periphery 1c of the rotor 1.

[0029] The ferrite bonded magnet 20 is magnetized so as to have a uniaxial anisotropic orientation. As a result, N poles and S poles are alternately formed in the circumferential direction on the outer periphery 20c of the ferrite bonded magnet 20.

[0030] The first portion 21 of the ferrite bonded magnet 20 has a plurality of groove portions 23 on the outer periphery 20c. The groove portions 23 are arranged at regular intervals in the circumferential direction. The groove portions 23 are formed at positions corresponding to the N pole and the S pole, respectively. The number of the groove portions 23 is the same as the number of poles P of the rotor 1. A rare earth bonded magnet 30 is arranged in each groove portion 23.

[0031] The groove portion 23 has a bottom surface 23a and a side surface 23b. The bottom surface 23a is a surface facing the outer side in the radial direction of the groove portion 23. The side surface 23b extends radially outward from both ends in the width direction of the bottom surface 23a. The side surface 23b is a boundary portion between the ferrite bonded magnet 20 and the rare earth bonded magnet 30.

[0032] In the ferrite bonded magnet 20, the magnetic flux flowing into the groove portion 23 of the S pole proceeds to the adjacent groove portion 23 of the N pole as shown by the broken line in Fig. 3(B). Therefore, it is not necessary to provide a rotor core constituting a magnetic path radially inside the ferrite bonded magnet 20. As a result, the number of parts in the rotor 1 can be reduced, and the rotor 1 can be lightened.

[0033] In the ferrite bonded magnet 20, the portion between the adjacent groove portions 23 of the N pole and the groove portions 23 of the S pole constitutes the inter-pole portion of the rotor 1.

[0034] <Configuration of the rare earth bonded magnet 30> The rare earth bonded 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 nitride magnet containing samarium (Sm), Fe, and nitrogen (N). The resin contained in the rare earth bonded magnet 30 is the same as, for example, the resin contained in the ferrite bonded magnet 20. That is, the resin contained in the rare earth bonded magnet 30 is at least one of, for example, nylon, PPS, and epoxy resin.

[0035] The strength of the magnetic pole (i.e., the magnetic quantity) of the rare earth bonded magnet 30 is greater than the strength of the magnetic pole of the ferrite bonded magnet 20. In other words, the magnetic force of the rare earth bonded magnet 30 is greater than the magnetic force of the ferrite bonded magnet 20. Thus, the rare earth bonded magnet 30 is formed of a material different from that of the ferrite bonded magnet 20 and has different magnetic properties.

[0036] The rare earth bonded magnets 30 are arranged at equal intervals in the circumferential direction. More specifically, the rare earth bonded magnets 30 are arranged in the groove portions 23 of the ferrite bonded magnet 20. In Embodiment 1, the ferrite bonded magnet 20 and the rare earth bonded magnets 30 are integrally molded (also referred to as "two-color molding"), whereby the rare earth bonded magnets 30 are joined to the groove portions 23 of the ferrite bonded magnet 20.

[0037] The rare earth bonded magnets 30 are magnetized so as to have a pole anisotropic orientation. The rare earth bonded magnets 30 adjacent to each other in the circumferential direction have magnetic poles with different polarities. The outer periphery 30c of the rare earth bonded magnet 30 forms a part of the outer periphery 1c of the rotor 1 (see Fig. 3(B)). The rare earth bonded magnet 30 constitutes the pole center of each magnetic pole.

[0038] The ferrite bonded magnet 20 and the rare earth bonded magnet 30 are integrally formed by filling the groove portion 23 with the raw material of the rare earth bonded magnet 30 in a state where the pre-manufactured ferrite bonded magnet 20 is placed in a mold. Compared with the manufacturing process of forming the ferrite bonded magnet 20 in a state where a plurality of pre-manufactured rare earth bonded magnets 30 are placed in a mold, the operation of placing the rare earth bonded magnets 30 one by one in the mold becomes unnecessary, so the manufacturing process of the rotor 1 can be simplified.

[0039] The rare earth bonded magnet 30 has an outer peripheral surface facing the radially outer side and an inner peripheral surface facing the radially inner side. In the example shown in FIG. 3(B), both the outer peripheral surface and the inner peripheral surface of the rare earth bonded magnet 30 are arc-shaped centered on the central axis Ax, but they do not necessarily have to be arc-shaped. In the cross-sectional view of the rotor orthogonal to the central axis Ax in FIG. 3(B) etc., the hatching of the ferrite bonded magnet 20 and the resin portion 40 is omitted.

[0040] FIG. 4(A) is a cross-sectional view taken along the line segment 4A-4A shown in FIG. 3(A), that is, a cross-sectional view of the rotor 1 on the plane passing through the overhang portion 52. As shown in FIG. 4(A), the overhang portion 52 of the rotor magnet 50 does not have the rare earth bonded magnet 30 and is composed only of the annular ferrite bonded magnet 20.

[0041] The outer diameter of the overhang portion 52 of the rotor magnet 50 is equal to the outer diameter of the stator facing portion 51. Therefore, the outer periphery of the second portion 22 of the ferrite bonded magnet 20 is on the same cylindrical surface as the outer periphery of the first portion 21 and forms a part of the above-described outer periphery 20c.

[0042] Since the ferrite bonded magnet 20 is magnetized as described with reference to FIG. 3(B), also in the overhang portion 52, the N pole and the S pole are alternately formed in the circumferential direction on the outer periphery of the ferrite bonded magnet 20. However, in the overhang portion 52, the groove portion 23 is not formed on the outer periphery of the ferrite bonded magnet 20.

[0043] Figure 4(B) is a cross-sectional view taken along line segment 4B-4B shown in Figure 3(B). As shown in Figure 4(B), the groove portion 23 of the ferrite bonded magnet 20 is formed in the first portion 21 and not formed in the second portion 22. Therefore, the stator facing portion 51 of the rotor magnet 50 has the rare earth bonded magnet 30, and the overhang portion 52 does not have the rare earth bonded magnet 30.

[0044] The ferrite bonded magnet 20 has an end face 20a that forms a part of the first end face 50a of the rotor magnet 50, and the groove portion 23 opens to the end face 20a. Therefore, the rare earth bonded magnet 30 has an end face 30a that forms a part of the first end face 50a of the rotor magnet 50.

[0045] <Action> Next, the operation of Embodiment 1 will be described in comparison with Comparative Examples 1 and 2. Figure 5(A) is a side view showing the rotor 1F of Comparative Example 1. Figure 5(B) is a cross-sectional view taken along line segment 5B-5B shown in Figure 5(A). Figure 5(C) is a cross-sectional view taken along line segment 5C-5C shown in Figure 5(B).

[0046] The rotor 1F of Comparative Example 1 has a shaft 10 and a rotor magnet 50 fixed to the shaft 10. The rotor magnet 50 has a ferrite bonded magnet 20 and an annular rare earth bonded magnet 34 that covers the outer periphery of the ferrite bonded magnet 20. The axial length Hr of the rotor magnet 50 is equal to the axial length Hs of the stator core 61 (Figure 1(B)). Also, the rare earth bonded magnet 30 is formed over the entire axial region of the rotor magnet 50.

[0047] In the rotor 1F of Comparative Example 1, the rare earth bonded magnet 34 is formed in an annular shape so as to cover the outer periphery of the ferrite bonded magnet 20. Therefore, the magnetic flux density distribution on the surface of the rotor magnet 50 can be made closer to a sine wave.

[0048] However, since the rare earth bonded magnet 34 is annular and has a radial thickness necessary to ensure strength, the amount of the rare earth bonded magnet 30 used increases. Since the unit material cost of the rare earth bonded magnet 30 is more than 10 times that of the ferrite bonded magnet 20, the manufacturing cost of the rotor 1F increases as the amount of the rare earth bonded magnet 30 used increases.

[0049] FIG. 6(A) is a side view showing the rotor 1G of Comparative Example 2. FIG. 6(B) is a cross-sectional view taken along the line segment 6B-6B shown in FIG. 6(A). FIG. 6(C) is a cross-sectional view taken along the line segment 6C-6C shown in FIG. 6(B).

[0050] The rotor 1G of Comparative Example 2 includes a shaft 10 and a rotor magnet 50 fixed to the shaft 10. The rotor magnet 50 includes a ferrite bonded magnet 20 and a plurality of rare earth bonded magnets 30 disposed on the outer periphery of the ferrite bonded magnet 20. The axial length Hr of the rotor magnet 50 is equal to the axial length Hs of the stator core 61 (FIG. 1(B)). Further, the rare earth bonded magnets 30 are formed over the entire axial region of the rotor magnet 50.

[0051] In the rotor 1G of Comparative Example 2, the rare earth bonded magnets 30 are arranged in a circumferentially dispersed manner. Therefore, compared with the rotor 1F of Comparative Example 1, the amount of the rare earth bonded magnet 30 used can be reduced by, for example, 20%, and the manufacturing cost of the rotor 1G can be reduced.

[0052] Further, although the magnetic force of the ferrite bonded magnet 20 is smaller than that of the rare earth bonded magnet 30, the rotor magnet 50 has a polar anisotropic orientation, and the rare earth bonded magnet 30 is disposed at the pole center. Therefore, it is possible to suppress a decrease in the surface magnetic flux density due to a small amount of the rare earth bonded magnet 30 used.

[0053] However, in the rotor 1G of Comparative Example 2, since the axial length Hr of the rotor magnet 50 is equal to the axial length Hs of the stator core 61, the magnetic flux flowing into the stator core 61 is only the magnetic flux flowing from the ferrite bonded magnet 20 and the rare earth bonded magnet 30 into the inner peripheral surface of the stator core 61. Therefore, it is difficult to increase the magnetic flux flowing into the stator core 61. Further, if the axial length Hr of the rotor magnet 50 is increased, the amount of the rare earth bonded magnet 30 used will increase accordingly, resulting in an increase in the manufacturing cost.

[0054] On the other hand, in the rotor 1 of Embodiment 1, similar to the rotor 1G of Comparative Example 2, since the rare earth bonded magnets 30 are arranged dispersedly in the circumferential direction (see Fig. 3(B)), the amount of the rare earth bonded magnets 30 used can be reduced, and the manufacturing cost can be lowered. Further, since the rare earth bonded magnets 30 are arranged at the pole centers, a decrease in the surface magnetic flux density can be suppressed.

[0055] Also, in the rotor 1 of Embodiment 1, since the rotor magnet 50 has the stator facing portion 51 and the overhang portion 52 (see Fig. 3(A)), not only does the magnetic flux flow from the stator facing portion 51 into the inner peripheral surface of the stator core 61, but also the magnetic flux flows from the overhang portion 52 into the axial end faces of the stator core 61. Therefore, the magnetic flux flowing into the stator core 61 can be increased as compared with Comparative Example 2.

[0056] Here, most of the magnetic flux emerging from the overhang portion 52 flows into the axial end faces of the stator core 61, but a part of the magnetic flux becomes leakage magnetic flux that does not flow into the stator core 61. Therefore, by forming the overhang portion 52 with the low magnetic force ferrite bonded magnet 20, the magnetic flux flowing into the stator core 61 can be increased while suppressing the manufacturing cost.

[0057] <Manufacturing Method of Rotor 1> Next, a method for manufacturing the rotor 1 will be described. FIG. 7 is a flowchart showing the manufacturing process of the rotor 1. In the manufacturing process of the rotor 1, a first mold for molding the ferrite bonded magnet 20, a second mold for molding the rare earth bonded magnet 30, an orienting magnet, and a magnetizer are used.

[0058] In step ST1, the inside of the first mold for molding the ferrite bonded magnet 20 is filled with the raw material of the ferrite bonded magnet 20. The ferrite bonded magnet 20 is molded by, for example, injection molding. Note that the ferrite bonded magnet 20 may be molded by other molding methods such as compression molding, not limited to injection molding.

[0059] In step ST2, while orienting the ferrite bonded magnet 20, it is molded into a predetermined shape. In step ST2, for example, using an orienting magnet, while generating a magnetically anisotropic magnetic field inside the first mold, the raw material of the ferrite bonded magnet 20 is oriented and the ferrite bonded magnet 20 is molded. Thereby, the ferrite bonded magnet 20 having magnetic anisotropy is molded.

[0060] In step ST3, the molded ferrite bonded magnet 20 is cooled.

[0061] In step ST4, the ferrite bonded magnet 20 is taken out from the first mold.

[0062] In step ST5, the taken-out ferrite bonded magnet 20 is demagnetized.

[0063] In step ST6, the ferrite bonded magnet 20 is placed inside the second mold for injection molding the rare earth bonded magnet 30.

[0064] In step ST7, the inside of the second mold is filled with the raw material of the rare earth bonded magnet 30. The rare earth bonded magnet 30 is molded by, for example, injection molding. Note that the rare earth bonded magnet 30 may be molded by other molding methods such as compression molding, not limited to injection molding.

[0065] As an example, as schematically shown in FIG. 8, the raw material of the rare earth bonded magnet 30 is filled into the groove portion 23 of the ferrite bonded magnet 20 disposed in the second mold. Since the groove portion 23 opens to the end face 20a (FIG. 4(B)) of the ferrite bonded magnet 20, the raw material of the rare earth bonded magnet 30 can be easily filled into the groove portion 23. Inside In step ST8, while orienting the raw material of the rare earth bonded magnet 30, it is formed into a predetermined shape. In step ST8, for example, using an orienting magnet, while generating a magnetic field having magnetic anisotropy inside the second mold, the raw material of the rare earth bonded magnet 30 is oriented and the rare earth bonded magnet 30 is formed. Thereby, the rotor magnet 50 in which the ferrite bonded magnet 20 and the plurality of rare earth bonded magnets 30 are integrally formed is formed.

[0066] In step ST9, the rotor magnet 50 formed in step ST8 is cooled.

[0067] In step ST10, the cooled rotor magnet 50 is taken out from the second mold.

[0068] In step ST11, the rotor magnet 50 taken out in step ST10 is demagnetized.

[0069] In step ST12, the rotor magnet 50 is connected to the shaft 10. As an example, the rotor magnet 50 and the shaft 10 are disposed in the third mold, and a thermoplastic resin such as PBT is filled to form the resin portion 40. Thereby, the rotor magnet 50 is connected to the shaft 10 via the resin portion 40.

[0070] In step ST13, for example, the rotor magnet 50 is magnetized using a magnetizer. Thereby, the rotor 1 is completed.

[0071] In step ST13, for example, the rotor magnet 50 is magnetized using a magnetizer. Thereby, the rotor 1 is completed.

[0072] Here, an example in which the overhang portion 52 does not have the rare-earth bonded magnet 30 and has only the ferrite bonded magnet 20 has been described. However, it is sufficient that the volume ratio of the rare-earth bonded magnet 30 to the ferrite bonded magnet 20 is smaller in the overhang portion 52 than in the stator facing portion 51.

[0073] As an example, the volume ratio of the rare-earth bonded magnet 30 to the ferrite bonded magnet 20 is, for example, 25% in the stator facing portion 51 and, for example, 0% in the overhang portion 52. An example in which the volume ratio of the rare-earth bonded magnet 30 is greater than 0% in the overhang portion 52 will be described in Embodiment 3.

[0074] Here, a configuration in which the overhang portion 52 is provided only at one axial end of the rotor magnet 50 has been described, but the overhang portion 52 may be provided at both axial ends of the rotor magnet 50. However, a configuration in which the overhang portion 52 is provided only at one axial end of the rotor magnet 50 is more desirable. With this configuration, since the groove portion 23 opens to the end face 20a of the ferrite bonded magnet 20 (see FIG. 4(B)), it is easy to fill the groove portion 23 with the raw material of the rare-earth bonded magnet 30 in step ST7 of FIG. 7, and the manufacturing process is simplified.

[0075] <Effect of Embodiment 1> As described above, in the first embodiment, the rotor magnet 50 of the rotor 1 includes a ferrite bonded magnet 20 as the first magnet and P (P is an integer of 2 or more) rare earth bonded magnets 30 as the second magnets. The ferrite bonded magnet 20 is magnetized to have a uniaxial anisotropic orientation. The rare earth bonded magnets 30 are arranged on the outer periphery of the ferrite bonded magnet 20, magnetized to have a uniaxial anisotropic orientation, and the magnetic pole strength is stronger than that of the ferrite bonded magnet 20. The axial length Hr of the rotor magnet 50 and the axial length Hs of the stator core 61 satisfy Hr > Hs. The rotor magnet 50 has a stator facing portion 51 that faces the stator core 61 in the radial direction and an overhang portion 52 that protrudes axially from the stator core 61 in the axial direction. The volume ratio of the rare earth bonded magnet 30 to the ferrite bonded magnet 20 is smaller in the overhang portion 52 than in the stator facing portion 51.

[0076] Since the rare earth bonded magnets 30 are thus arranged in a dispersed manner in the circumferential direction, the amount of the rare earth bonded magnets 30 used can be reduced, and the manufacturing cost of the electric motor 100 can be reduced. Further, since the rotor magnet 50 has the stator facing portion 51 and the overhang portion 52, the effective magnetic flux flowing into the stator core 61 can be increased. Furthermore, since the volume ratio of the rare earth bonded magnet 30 to the ferrite bonded magnet 20 is smaller in the overhang portion 52 than in the stator facing portion 51, the manufacturing cost can be reduced without reducing the output and efficiency of the electric motor 100.

[0077] In particular, since the overhang portion 52 of the rotor magnet 50 has no rare earth bonded magnet 30 and has only the ferrite bonded magnet 20, the amount of the rare earth bonded magnets 30 used can be further reduced, and the manufacturing cost can be further reduced.

[0078] <<Second Embodiment>> Next, the second embodiment will be described. The configuration of the rotor 1A of the second embodiment is different from that of the electric motor 100 of the first embodiment. FIG. 9(A) is a side view showing the rotor 1A of the second embodiment. In FIG. 9(A), a part of the stator 6 is shown by a dashed line.

[0079] The rotor 1A has a shaft 10 and rotor magnets 50, similar to the rotor 1 in the first embodiment. The rotor magnets 50 include a ferrite bonded magnet 20 as the first magnet and a plurality of rare earth bonded magnets 30 as the second magnets. Further, the rotor magnets 50 have a stator facing portion 51 and an overhang portion 52 in the axial direction.

[0080] FIG. 9(B) is a cross-sectional view taken along the line segment 9B-9B shown in FIG. 9(A), that is, a cross-sectional view of the rotor 1A on the plane passing through the stator facing portion 51. As shown in FIG. 9(B), in the second embodiment, the shape of the groove portion 23 of the ferrite bonded magnet 20 and the shape of the rare earth bonded magnet 30 are different from those in the first embodiment.

[0081] FIG. 9(C) is an enlarged view showing one groove portion 23 of the ferrite bonded magnet 20 and the rare earth bonded magnet 30 disposed in the groove portion 23. The groove portion 23 has a bottom surface 23a and side surfaces 23b. The bottom surface 23a is a surface facing the outer side in the radial direction of the groove portion 23. The side surfaces 23b extend radially outward from both ends in the width direction of the bottom surface 23a.

[0082] In FIG. 9(C), the bottom surface 23a extends in an arc shape convex toward the inner side in the radial direction, but is not limited to such a shape and may extend in an arc shape convex toward the outer side in the radial direction or may extend linearly.

[0083] The rare earth bonded magnet 30 has an outer peripheral surface 31 facing the outer side in the radial direction, an inner peripheral surface 32 facing the inner side in the radial direction, and side surfaces 33 on both sides in the circumferential direction. The outer peripheral surface 31 extends in an arc shape centered on the central axis Ax. The inner peripheral surface 32 extends in an arc shape convex toward the inner side in the radial direction. However, if the inner peripheral surface 32 has a shape corresponding to the bottom surface 23a, it may extend in an arc shape convex toward the outer side in the radial direction or may extend linearly.

[0084] In a plane orthogonal to the central axis Ax, the length W2 of the inner peripheral surface 32 of the rare earth bonded magnet 30 is longer than the length W1 of the outer peripheral surface 31. Therefore, in a plane orthogonal to the central axis Ax, the length of the bottom surface 23a of the groove portion 23 of the ferrite bonded magnet 20 is longer than the length of the opening portion on the outer periphery 20c side of the groove portion 23.

[0085] Because of this configuration, the rare earth bonded magnet 30 is held in the groove portion 23 of the ferrite bonded magnet 20 so as not to drop radially outward. Therefore, even if peeling occurs at the interface due to the difference in the coefficient of thermal expansion between the ferrite bonded magnet 20 and the rare earth bonded magnet 30, or even if a centrifugal force due to the rotation of the rotor 1A acts, the rare earth bonded magnet 30 can be prevented from dropping off from the ferrite bonded magnet 20.

[0086] FIG. 10(A) is a cross-sectional view taken along the line segment 10A-10A shown in FIG. 9(A), that is, a cross-sectional view of the rotor 1A in a plane passing through the overhang portion 52. FIG. 10(B) is a cross-sectional view taken along the line segment 10B-10B shown in FIG. 9(B). As shown in FIGS. 10(A) and 10(B), the configuration of the overhang portion 52 of the rotor magnet 50 is the same as that of the first embodiment.

[0087] The rotor 1A of the second embodiment is configured in the same manner as the rotor 1 of the first embodiment except for the above-described points.

[0088] As described above, in the second embodiment, since the length W2 of the inner peripheral surface 32 of the rare earth bonded magnet 30 is longer than the length W1 of the outer peripheral surface 31, the rare earth bonded magnet 30 can be prevented from dropping off from the ferrite bonded magnet 20, and the reliability of the motor can be improved.

[0089] <<Third Embodiment>> Next, the third embodiment will be described. The motor of the third embodiment is different from the motor 100 of the first embodiment in the configuration of the rotor 1B. FIG. 11(A) is a side view showing the rotor 1B of the third embodiment. In FIG. 11(A), a part of the stator 6 is shown by a broken line.

[0090] The rotor 1B has a shaft 10 and rotor magnets 50, similar to the rotor 1 in Embodiment 1. The rotor magnets 50 have a ferrite bonded magnet 20 as the first magnet and a plurality of rare earth bonded magnets 30 as the second magnets. Further, the rotor magnets 50 have a stator facing portion 51 and an overhang portion 52 in the axial direction.

[0091] FIG. 11(B) is a cross-sectional view taken along the line segment 11B-11B shown in FIG. 11(A), that is, a cross-sectional view of the rotor 1B on a plane passing through the stator facing portion 51. As shown in FIG. 11(B), the shape of the stator facing portion 51 in Embodiment 3 is the same as that in Embodiment 1.

[0092] FIG. 12(A) is a cross-sectional view taken along the line segment 12A-12A shown in FIG. 11(A), that is, a cross-sectional view of the rotor 1B on a plane passing through the overhang portion 52. FIG. 12(B) is a cross-sectional view taken along the line segment 12B-12B shown in FIG. 11(B).

[0093] As shown in FIG. 12(A), in the ferrite bonded magnet 20 of the overhang portion 52, that is, the second portion 22, recesses 25 are formed at positions corresponding to the centers of the N-pole and S-magnet poles. Here, the recess 25 is a hole having a circular cross-section, but the cross-sectional shape of the recess 25 is not limited to a circle.

[0094] As shown in FIG. 12(B), the recess 25 is formed continuously in the axial direction from the groove portion 23. Further, the rare earth bonded magnet 30 has a convex portion 35 accommodated in the recess 25. The recess 25 is also referred to as a first engaging portion, and the convex portion 35 is also referred to as a second engaging portion.

[0095] The convex portion 35 of the rare earth bonded magnet 30 is formed by filling the raw material of the rare earth bonded magnet 30 into the groove portion 23 of the ferrite bonded magnet 20 disposed in the second mold in the process of step ST7 in FIG. 7, so that the raw material is filled from the groove portion 23 into the recess 25.

[0096] In Embodiment 3, the overhang portion 52 has not only the ferrite bonded magnet 20 but also the rare earth bonded magnet 30 (i.e., the convex portion 35). However, the volume ratio of the rare earth bonded magnet 30 to the ferrite bonded magnet 20 is smaller in the overhang portion 52 than in the stator facing portion 51.

[0097] Since the convex portion 35 of the rare earth bonded magnet 30 engages with the concave portion 25 of the ferrite bonded magnet 20, the rare earth bonded magnet 30 can be firmly fixed to the ferrite bonded magnet 20. That is, even if peeling occurs at the interface due to the difference in the thermal expansion coefficients between the ferrite bonded magnet 20 and the rare earth bonded magnet 30, or even if a centrifugal force due to the rotation of the rotor 1B acts, the rare earth bonded magnet 30 can be prevented from falling off the ferrite bonded magnet 20.

[0098] The rotor 1B of Embodiment 3 is configured in the same manner as the rotor 1 of Embodiment 1 except for the above-described points. As described in Embodiment 2, the length W2 of the inner peripheral surface 32 of the rare earth bonded magnet 30 may be made longer than the length W1 of the outer peripheral surface 31.

[0099] As described above, in Embodiment 3, since the convex portion 35 of the rare earth bonded magnet 30 engages with the concave portion 25 of the ferrite bonded magnet 20, the rare earth bonded magnet 30 can be prevented from falling off the ferrite bonded magnet 20, and the reliability of the motor can be improved.

[0100] Here, an example in which the ferrite bonded magnet 20 has the concave portion 25 and the rare earth bonded magnet 30 has the convex portion 35 has been described. However, as in the modified example shown in FIG. 12(C), the ferrite bonded magnet 20 may have the convex portion 27 and the rare earth bonded magnet 30 may have the concave portion 37.

[0101] In this case, in the process of step ST7 in FIG. 7, by molding the rare earth bonded magnet 30 so as to cover the convex portion 27 of the ferrite bonded magnet 20, the concave portion 37 can be formed. Also in this modification, by engaging the convex portion 27 of the ferrite bonded magnet 20 with the concave portion 37 of the rare earth bonded magnet 30, the effect of preventing the rare earth bonded magnet 30 from falling off can be obtained.

[0102] <<Embodiment 4>> Next, Embodiment 4 will be described. The motor of Embodiment 4 differs from the motor 100 of Embodiment 1 in the configuration of the rotor 1C. FIG. 13(A) is a side view showing the rotor 1C of Embodiment 4. In FIG. 13(A), a part of the stator 6 is shown by a dashed line.

[0103] The rotor 1C has a shaft 10 and rotor magnets 50, similar to the rotor 1 of Embodiment 1. The rotor magnets 50 include a ferrite bonded magnet 20 as the first magnet and a plurality of rare earth bonded magnets 30 as the second magnets. Further, the rotor magnets 50 have a stator facing portion 51 and an overhang portion 52 in the axial direction.

[0104] FIG. 13(B) is a cross-sectional view taken along the line segment 13B-13B shown in FIG. 13(A), in other words, a cross-sectional view of the rotor 1C on a plane passing through a portion near the first end face 50a of the rotor magnet 50. The rare earth bonded magnet 30 has an overhanging portion 36 that protrudes radially inward at an end on the first end face 50a side. The overhanging portion 36 of the rare earth bonded magnet 30 is exposed on the first end face 50a (FIG. 13(A)) of the rotor magnet 50.

[0105] FIG. 14(A) is a cross-sectional view taken along line segment 14A-14A shown in FIG. 13(A), in other words, a cross-sectional view of the rotor 1C on a plane passing through the overhang portion 52. FIG. 14(B) is a cross-sectional view taken along line segment 14B-14B shown in FIG. 13(B). As shown in FIG. 14(A), the ferrite bonded magnet 20 in the overhang portion 52, that is, the second portion 22, is formed with the recess 25 described in Embodiment 3. Inside the recess 25, the convex portion 35 of the rare earth bonded magnet 30 described in Embodiment 3 is accommodated.

[0106] As shown in FIG. 14(B), the ferrite bonded magnet 20 (that is, the first portion 21) in the stator facing portion 51 has a receiving portion 26 that extends radially inward from the groove portion 23 along the first end face 50a. The protruding portion 36 of the rare earth bonded magnet 30 is accommodated in the receiving portion 26. Since the receiving portion 26 is formed in a stepped shape with respect to the groove portion 23 in the cross-section of FIG. 14(B), it is also referred to as a stepped portion.

[0107] The protruding portion 36 of the rare earth bonded magnet 30 is formed by filling the groove portion 23 of the ferrite bonded magnet 20 disposed in the mold with the raw material of the rare earth bonded magnet 30 in the process of step ST7 in FIG. 7, so that the raw material is filled from the groove portion 23 into the receiving portion 26.

[0108] Since the protruding portion 36 of the rare earth bonded magnet 30 engages with the receiving portion 26 of the ferrite bonded magnet 20, the rare earth bonded magnet 30 can be firmly fixed to the ferrite bonded magnet 20. That is, even if peeling occurs at the interface due to the difference in the thermal expansion coefficients of the ferrite bonded magnet 20 and the rare earth bonded magnet 30, or centrifugal force acts due to the rotation of the rotor 1C, the rare earth bonded magnet 30 can be prevented from falling off.

[0109] The rotor 1C of Embodiment 4 is configured in the same manner as the rotor 1 of Embodiment 1 except for the above-described points.

[0110] As described above, in the fourth embodiment, since the overhanging portion 36 of the rare earth bonded magnet 30 engages with the receiving portion 26 of the ferrite bonded magnet 20, the rare earth bonded magnet 30 can be prevented from falling off the ferrite bonded magnet 20, and the reliability of the motor can be improved. Further, since the overhanging portion 36 of the rare earth bonded magnet 30 is formed at the end on the first end face 50a side of the rotor magnet 50, molding using a mold is easy.

[0111] Note that in FIGS. 14(A) and 14(B), the rotor magnet 50 has the concave portion 25 and the convex portion 35 described in the third embodiment, but it is not necessarily required to have the concave portion 25 and the convex portion 35. Further, the convex portion 27 and the concave portion 37 shown in FIG. 12(C) may be provided. Further, as described in the second embodiment, the length W2 of the inner peripheral surface 32 of the rare earth bonded magnet 30 may be made longer than the length W1 of the outer peripheral surface 31.

[0112] 《Fifth Embodiment》 Next, the fifth embodiment will be described. The motor of the fifth embodiment is different from the motor 100 of the first embodiment in the configuration of the rotor 1D. FIG. 15(A) is a side view showing the rotor 1D of the fifth embodiment. In FIG. 15(A), a part of the stator 6 is shown by a broken line.

[0113] The rotor 1D has a shaft 10 and a rotor magnet 50, similar to the rotor 1 of the first embodiment. The rotor magnet 50 has a ferrite bonded magnet 20 as the first magnet and a plurality of rare earth bonded magnets 30 as the second magnets. Further, the rotor magnet 50 has a stator facing portion 51 and an overhang portion 52 in the axial direction.

[0114] FIG. 15(B) is a cross-sectional view taken along the line segment 15B-15B shown in FIG. 15(A), that is, a cross-sectional view of the rotor 1D on a plane passing through the stator facing portion 51. As shown in FIGS. 15(A) and 15(B), the outer diameter of the second portion 22 of the ferrite bonded magnet 20 is larger than the outer diameter of the first portion 21 of the ferrite bonded magnet 20. In other words, the outer periphery 22c of the second portion 22 protrudes radially outward from the outer periphery 21c of the first portion 21.

[0115] Therefore, in the rotor 1D, the outer diameter of the overhang portion 52 is larger than the outer diameter of the stator facing portion 51. More specifically, the distance R1 from the central axis Ax to the outer periphery of the stator facing portion 51 and the distance R2 from the central axis Ax to the outer periphery of the overhang portion 52 satisfy R1 < R2.

[0116] FIG. 16(A) is a cross-sectional view taken along the line segment 16A-16A shown in FIG. 15(A), that is, a cross-sectional view of the rotor 1D on a plane passing through the overhang portion 52. FIG. 16(B) is a cross-sectional view taken along the line segment 16B-16B shown in FIG. 15(B). As shown in FIGS. 16(A) and 16(B), the ferrite bonded magnet 20 is formed in the same manner as the ferrite bonded magnet 20 of the first embodiment, except that the outer diameter of the second portion 22 is larger than the outer diameter of the first portion 21. Also, the rare earth bonded magnet 30 is formed in the same manner as the rare earth bonded magnet 30 of the first embodiment.

[0117] Since the stator facing portion 51 faces the stator core 61 via an air gap, there is a limit to increasing the outer diameter of the stator facing portion 51. On the other hand, since the overhang portion 52 protrudes axially from the stator core 61, the outer diameter can be made larger than that of the stator facing portion 51.

[0118] By increasing the outer diameter of the overhang portion 52 in this way, the magnetic flux flowing into the stator core 61 via the overhang portion 52 can be increased.

[0119] The rotor 1D of the fifth embodiment is configured in the same manner as the rotor 1 of the first embodiment, except for the points described above.

[0120] As described above, in the fifth embodiment, since the outer diameter of the overhang portion 52 is larger than the outer diameter of the stator facing portion 51, the magnetic flux flowing into the stator core 61 can be increased.

[0121] In addition, the features described in Embodiment 5 may be combined with those described in Embodiment 2, Embodiment 3, the modification example, or Embodiment 4.

[0122] 《Embodiment 6》 Next, Embodiment 6 will be described. The motor of Embodiment 6 differs from the motor 100 of Embodiment 1 in the configuration of the rotor 1E. FIG. 17(A) is a side view showing the rotor 1E of Embodiment 6. FIG. 17(B) is a plan view showing the rotor 1E. In FIG. 17(A), a part of the stator 6 is shown by a broken line.

[0123] The rotor 1E has a shaft 10 and rotor magnets 50, similar to the rotor 1 of Embodiment 1. The rotor magnet 50 has a ferrite bonded magnet 20 as a first magnet and a plurality of rare earth bonded magnets 30 as second magnets. Further, the rotor magnet 50 has a stator facing portion 51 and an overhang portion 52 in the axial direction.

[0124] As shown in FIGS. 17(A) and 17(B), the rotor 1E has a ring-shaped cover member 70 so as to cover the first end face 50a of the rotor magnet 50. The cover member 70 covers the end face 20a of the ferrite bonded magnet 20 and also covers the end face 30a of the rare earth bonded magnet 30. Note that the cover member 70 only needs to cover at least a part of each of the ferrite bonded magnet 20 and the rare earth bonded magnet 30.

[0125] The cover member 70 is formed of resin. More specifically, the cover member 70 is formed of a resin different from the ferrite bonded magnet and the rare earth bonded magnet. In particular, it is desirable that the cover member 70 is formed of the same material as the resin part 40, for example, a thermoplastic resin such as PBT.

[0126] FIG. 18(A) is a cross-sectional view taken along the line segment 16A-16A shown in FIG. 17(A), that is, a cross-sectional view of the rotor 1E on the plane passing through the overhang portion 52. FIG. 18(B) is a cross-sectional view taken along the line segment 18B-18B shown in FIG. 17(B).

[0127] As shown in Fig. 18(A), the second portion 22 of the ferrite bonded magnet 20 has the recess 25 described in Embodiment 3, and the convex portion 35 of the rare earth bonded magnet 30 is accommodated in the recess 25.

[0128] As shown in Fig. 18(B), it is desirable that the cover member 70 is integrally formed with the resin portion 40. In this case, in step ST12 of Fig. 7, by arranging the shaft 10 and the rotor magnet 50 in the third mold and filling them with a thermoplastic resin such as PBT, the resin portion 40 and the cover member 70 can be integrally molded. Thereby, the manufacturing process of the rotor 1E can be simplified.

[0129] In this case, by adjusting the dimensions etc. of the rib 43 of the resin portion 40, the natural frequency and inertia of the rotor 1E can be adjusted.

[0130] Since the natural frequency of the rotor 1E depends on the rigidity of the rotor 1E, it can be adjusted by changing the radial length, circumferential width or number of the ribs 43. By adjusting the natural frequency of the rotor 1E, vibration due to resonance can be suppressed.

[0131] Also, since the inertia of the rotor 1E depends on the mass of the rotor 1E, it can be adjusted by changing the radial length, circumferential width or number of the ribs 43. If the inertia of the rotor 1E is increased, the torque required at startup increases, but the rotation of the rotor 1E can be stabilized.

[0132] Here, the cover member 70 is provided on the first end face 50a of the rotor magnet 50, but the cover member 70 may be provided on both the first end face 50a and the second end face 50b. In this case, the integrity of the rotor 1E can be further enhanced.

[0133] Also, unevenness may be provided on the end face 20a of the ferrite bonded magnet 20 and the end face 30a of the rare earth bonded magnet 30, and the cover member 70 may be formed so as to cover this unevenness.

[0134] The rotor 1E of Embodiment 6 is configured in the same manner as the rotor 1 of Embodiment 1, except for the above-described points.

[0135] As described above, since the rotor 1E of Embodiment 6 has the cover member 70 that covers at least a part of each of the ferrite bonded magnet 20 and the rare earth bonded magnet 30 on the first end face 50a of the rotor magnet 50, the rare earth bonded magnet 30 can be firmly fixed to the ferrite bonded magnet 20. Therefore, it is possible to prevent the rare earth bonded magnet 30 from falling off from the ferrite bonded magnet 20 due to temperature changes or centrifugal force.

[0136] Further, if the cover member 70 is integrally formed of the same material as the resin portion 40, the shaft 10 and the rotor magnet 50 can be arranged in the mold and filled with resin, and the resin portion 40 and the cover member 70 can be integrally molded. Therefore, the manufacturing process of the rotor 1E can be simplified.

[0137] Note that the features described in Embodiment 2, Embodiment 3, the modification example, Embodiment 4, or Embodiment 5 may be combined with Embodiment 6.

[0138] <<Embodiment 7>> Next, the configuration of the blower 200 according to Embodiment 7 will be described. FIG. 19 is a diagram schematically showing the configuration of the blower 200 according to Embodiment 7.

[0139] As shown in FIG. 19, the blower 200 includes an electric motor 100 and a fan 201 as an impeller driven by the electric motor 100. The fan 201 is attached to the shaft 10 (FIG. 1) of the electric motor 100. When the shaft 10 of the electric motor 100 rotates, the fan 201 rotates and an air flow is generated. The blower 200 is used, for example, as an outdoor blower of the outdoor unit 320 of an air conditioner 300 (FIG. 20) described later. In this case, the fan 201 is, for example, a propeller fan.

[0140] Since the blower 200 according to Embodiment 7 has the electric motor 100 described in Embodiment 1, it is possible to reduce the manufacturing cost while suppressing a decrease in the output and efficiency of the blower 200. Even when the electric motors described in Embodiments 2 to 6 are used instead of the electric motor 100 described in Embodiment 1, the same effects can be obtained.

[0141] <<Embodiment 8>> Next, the configuration of the air conditioner 300 having the blower 200 according to Embodiment 8 will be described. FIG. 20 is a diagram showing the configuration of the air conditioner 300 according to Embodiment 8.

[0142] As shown in FIG. 20, the air conditioner 300 includes an indoor unit 310 and an outdoor unit 320. The indoor unit 310 and the outdoor unit 320 are connected by a refrigerant pipe 330 to form a refrigerant circuit in which the refrigerant circulates. The air conditioner 300 can perform operations such as a cooling operation of blowing cold air from the indoor unit 310 or a heating operation of blowing warm air.

[0143] The indoor unit 310 includes an indoor blower 311 and a housing 312 that houses the indoor blower 311. The indoor blower 311 includes an electric motor 311a and a fan 311b driven by the electric motor 311a. The fan 311b is attached to the shaft of the electric motor 311a. When the shaft of the electric motor 311a rotates, the fan 311b rotates to generate an air flow. The fan 311b is, for example, a cross-flow fan.

[0144] The outdoor unit 320 includes a blower 200 as an outdoor blower, a compressor 321, and a housing 322 that houses the blower 200 and the compressor 321. The compressor 321 includes a compression mechanism portion 321a that compresses the refrigerant and an electric motor 321b that drives the compression mechanism portion 321a. The compression mechanism portion 321a and the electric motor 321b are connected to each other by a shaft 321c. Note that the electric motor 100 according to Embodiment 1 may be used for the electric motor 321b of the compressor 321.

[0145] For example, during the cooling operation of the air conditioner 300, the heat released when the refrigerant compressed by the compressor 321 condenses in a condenser (not shown) is discharged outdoors by the blowing of the blower 200. The outdoor unit 320 further has a four-way valve (not shown) for switching the flow direction of the refrigerant. The four-way valve of the outdoor unit 320 sends the high-temperature and high-pressure refrigerant gas sent out from the compressor 321 to the heat exchanger of the outdoor unit 320 during the cooling operation and to the heat exchanger of the indoor unit 310 during the heating operation.

[0146] Note that the blower 200 is not limited to the outdoor blower of the outdoor unit 320 and may be used as the above-described indoor blower 311. Also, the blower 200 is not limited to the air conditioner 300 and may be provided in other electrical devices.

[0147] Since the air conditioner 300 of the eighth embodiment has the blower 200 described in the seventh embodiment, it is possible to reduce the manufacturing cost while suppressing a decrease in the output and efficiency of the air conditioner 300.

[0148] As described above, the desirable embodiments have been specifically described. However, the present disclosure is not limited to the above embodiments, and various improvements or modifications can be made.

Description of Reference Numerals

[0149] 1, 1A, 1B, 1C, 1D, 1E rotor, 6 stators, 8 circuit boards, 10 shafts, 20 ferrite bonded magnets (first magnet), 21 first part, 22 second part, 23 groove portion, 23a bottom surface, 23b side surface, 25 recess, 26 receiving portion, 27 protrusion, 30 rare earth bonded magnet (second magnet), 31 outer peripheral surface, 32 inner peripheral surface, 33 side surface, 34 rare earth bonded magnet, 35 protrusion, 36 overhang portion, 37 recess, 40 resin portion (holding portion), 41 inner cylinder portion, 42 outer cylinder portion, 43 rib, 50 rotor magnet, 50a first end face (end face), 50b second end face, 51 stator facing portion, 52 overhang portion, 61 stator core, 62 coil, 70 cover member, 100 motor, 200 blower, 201 fan, 300 air conditioner, 310 indoor unit, 311 indoor blower, 320 outdoor unit, 321 compressor.

Claims

1. A rotor having a shaft and a rotor magnet fixed to the shaft, and a stator surrounding the rotor from the outside in the radial direction centered on the shaft are provided, wherein the rotor magnet includes a first magnet magnetized to have a magnetic anisotropic orientation, and P (P is an even number) second magnets arranged on the outer periphery of the first magnet, magnetized to have a magnetic anisotropic orientation, and having magnetic poles stronger than those of the first magnet are provided, the stator includes a stator core and a coil wound around the stator core, the axial length Hr of the shaft of the rotor magnet and the axial length Hs of the stator core satisfy Hr > Hs, the rotor magnet has, in the axial direction, a stator facing portion facing the stator core in the radial direction and an overhang portion protruding from the stator core in the axial direction, the first magnet has P grooves provided at equal intervals on the outer periphery of the stator facing portion, the P grooves are formed so as not to reach the end face on the side opposite to the stator facing portion of the overhang portion in the axial direction, the P second magnets are respectively arranged in the P grooves, the volume ratio of the second magnet to the first magnet is smaller in the overhang portion than in the stator facing portion motor.

2. A rotor having a shaft and a rotor magnet fixed to the shaft, and a stator surrounding the rotor from the outside in the radial direction centered on the shaft are provided, wherein the rotor magnet includes a first magnet magnetized to have a magnetic anisotropic orientation, and P (P is an even number) second magnets arranged on the outer periphery of the first magnet, magnetized to have a magnetic anisotropic orientation, and having magnetic poles stronger than those of the first magnet are provided, the stator includes a stator core and a coil wound around the stator core, the axial length Hr of the shaft of the rotor magnet and the axial length Hs of the stator core satisfy Hr > Hs, the rotor magnet has, in the axial direction, a stator facing portion facing the stator core in the radial direction and an overhang portion protruding from the stator core in the axial direction, the first magnet has P grooves provided at equal intervals on the outer periphery of the stator facing portion, the P second magnets are respectively arranged in the P grooves, The volume ratio of the second magnet to the first magnet is smaller in the overhang portion than in the stator facing portion. The overhang portion has the first magnet and does not have the second magnet. Motor.

3. The second magnet has an outer peripheral surface facing the outside in the radial direction and an inner peripheral surface facing the inside in the radial direction. In a plane orthogonal to the axial direction, the length of the inner peripheral surface is longer than the length of the outer peripheral surface. The motor according to claim 1 or 2.

4. The first magnet has a recess in a portion in contact with the second magnet. The second magnet has a protrusion that is received in the recess of the first magnet. The motor according to claim 1.

5. The first magnet has a protrusion in a portion in contact with the second magnet. The second magnet has a recess that surrounds the protrusion of the first magnet. The motor according to claim 1 or 2.

6. The second magnet has an overhang portion that projects inward in the radial direction along an end surface on the side opposite to the overhang portion of the rotor magnet. The first magnet has a receiving portion that receives the overhang portion of the second magnet. The motor according to claim 1 or 2.

7. A rotor having a shaft and a rotor magnet fixed to the shaft, A stator that surrounds the rotor from the outside in the radial direction with the shaft as the center And having The rotor magnet is A first magnet magnetized to have a pole anisotropic orientation, P (P is an even number) second magnets that are arranged on the outer periphery of the first magnet, magnetized to have a pole anisotropic orientation, and have stronger magnetic poles than the first magnet And having The stator has a stator core and a coil wound around the stator core. The axial length Hr of the shaft of the rotor magnet and the axial length Hs of the stator core satisfy Hr > Hs. The rotor magnet has, in the axial direction, a stator facing portion that faces the stator core in the radial direction and an overhang portion that projects axially from the stator core. The first magnet has P groove portions provided at equal intervals on the outer periphery in the stator facing portion. The P second magnets are respectively arranged in the P groove portions. The volume ratio of the second magnet to the first magnet is smaller in the overhang portion than in the stator facing portion. The distance R1 from the central axis of the shaft to the outer periphery of the stator facing portion and the distance R2 from the central axis to the outer periphery of the overhang portion satisfy R1 < R2 Electric motor

8. On the end face of the rotor magnet opposite to the overhang portion, there is a cover member covering at least a part of the first magnet and at least a part of the second magnet The electric motor according to claim 1, 2 or 7

9. Further having a holding portion for connecting the rotor magnet and the shaft, The cover member is made of the same material as the holding portion and is integrally formed with the holding portion The electric motor according to claim 8

10. The first magnet is a ferrite bonded magnet, The second magnet is a rare earth bonded magnet The electric motor according to claim 1, 2 or 7

11. The electric motor according to claim 1, 2 or 7, and An impeller driven by the electric motor A blower having the above

12. An indoor unit, and An outdoor unit connected to the indoor unit Having the above, At least one of the indoor unit and the outdoor unit has the blower according to claim 11 An air conditioner

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