CN110999034B

CN110999034B - Rotor and motor

Info

Publication number: CN110999034B
Application number: CN201880050949.9A
Authority: CN
Inventors: 田中邦明
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2017-09-25
Filing date: 2018-06-29
Publication date: 2022-04-05
Anticipated expiration: 2038-06-29
Also published as: WO2019058699A1; CN110999034A

Abstract

A rotor of an alternating motor, the rotor having: a shaft that rotates around a central axis extending in the vertical direction; a rotor core fixed to the shaft; and a plurality of magnets that are included in the rotor core and are provided at intervals in a circumferential direction around the central axis, wherein the rotor core is provided with salient pole portions that protrude outward in a radial direction around the central axis between the magnets adjacent to each other in the circumferential direction, the coercive force of the magnets is 1400kA/m or more, and the radial thickness of the magnets is 2.6mm or more.

Description

Rotor and motor

Technical Field

The invention relates to a rotor and a motor.

Background

The rotor of the motor has: a rotor core that rotates together with the shaft; and a plurality of magnets arranged along a circumferential direction of the rotor core. As such a rotor, a so-called alternating rotor is known. For example, japanese laid-open patent publication No. 2010-246233 discloses an alternating rotor in which salient poles are provided between magnets adjacent to each other in the circumferential direction. The rotor has a magnet as one magnetic pole and a salient pole as the other magnetic pole.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open publication No. 2010-246233

Disclosure of Invention

Problems to be solved by the invention

In the alternating rotor as described above, there is a problem that the demagnetization rate becomes larger than that of a general rotor in which one magnetic pole and the other magnetic pole are alternately formed by a plurality of magnets provided in the circumferential direction (hereinafter, such a rotor is referred to as a full-magnet rotor). In the case of a full-magnet type rotor, magnetic flux emitted from a magnet constituting one magnetic pole reaches another magnet constituting the other magnetic pole. In contrast, in the alternating rotor, most of the magnetic flux emitted from the magnet constituting one magnetic pole reaches the salient pole constituting the other magnetic pole, but a part of the magnetic flux returns to the magnet itself. Therefore, a reverse magnetic field acts on the magnet, and the demagnetization factor increases.

In order to suppress an increase in the demagnetization factor, it is considered to increase the coercive force of the magnet. However, if it is desired to ensure a demagnetization factor equivalent to that of the full-magnet rotor in the same size as that of the magnet used for the full-magnet rotor, the magnet used for the alternating-type rotor needs to have a very high coercive force. As a result, the cost of the magnet increases significantly, leading to an increase in the cost of the motor.

In view of the above, an object of the present invention is to provide a rotor and a motor that can suppress an increase in demagnetization factor while suppressing the cost of a magnet.

Means for solving the problems

One aspect of the present invention is a rotor of an alternating-type motor, the rotor including: a shaft that rotates around a central axis extending in the vertical direction; a rotor core fixed to the shaft; and a plurality of magnets that are included in the rotor core and are provided at intervals in a circumferential direction around the central axis, wherein the rotor core is provided with salient pole portions that protrude outward in a radial direction around the central axis between the magnets adjacent to each other in the circumferential direction, the coercive force of the magnets is 1400kA/m or more, and the radial thickness of the magnets is 2.6mm or more.

One embodiment of the present invention is a motor including: the rotor described above; and a stator facing the rotor with a gap in a radial direction, the rotor having 10 magnetic poles each including the magnet and the salient pole portion, and the stator having 12 slots for coils for applying a magnetic field to the rotor.

Effects of the invention

According to one embodiment of the present invention, a rotor and a motor are provided which can suppress an increase in demagnetization factor while suppressing the cost of a magnet.

Drawings

FIG. 1 is a schematic cross-sectional view of a motor according to one embodiment.

Fig. 2 is a sectional view of a motor according to an embodiment.

FIG. 3 is a cross-sectional view of one embodiment of a rotor.

Fig. 4 is an enlarged sectional view showing a part of a rotor of one embodiment.

Fig. 5 is a graph showing a relationship between a radial thickness of a magnet and a demagnetization factor in a case where the coercive force of the magnet is made different in the rotor according to the embodiment.

Fig. 6 is a graph showing changes in the proportion of induced voltage per unit volume when the radial thickness of the magnet is varied in the rotor according to the embodiment.

Fig. 7 is a diagram showing a structure of a full-magnet rotor as a comparison target with the rotor according to the embodiment.

Detailed Description

Fig. 1 is a schematic sectional view of a motor 10 of the present embodiment. As shown in fig. 1, the motor 10 includes a housing 11, a stator 12, a rotor 13, a bearing holder 14, and

bearings

15 and 16, wherein the rotor 13 has a shaft 20 disposed along a central axis J extending in the vertical direction. The shaft 20 is rotatably supported by the

bearings

15 and 16. The shaft 20 has a cylindrical shape extending in a direction along the center axis J.

In the following description, a direction parallel to the central axis J is simply referred to as an "axial direction" or a "vertical direction", a radial direction about the central axis J is simply referred to as a "radial direction", and a circumferential direction about the central axis J (i.e., a direction around the central axis J) is simply referred to as a "circumferential direction". In the following description, the term "plan view" means a state viewed from the axial direction. In the drawings below, for convenience of understanding of the respective structures, the actual structures may be different in scale, number, and the like from those of the respective structures.

Fig. 2 is a sectional view of the motor of the present embodiment. As shown in fig. 2, the stator 12 is radially opposed to the rotor 13 at a radially outer side of the rotor 13 with a gap therebetween. The stator 12 has: a plurality of teeth 17 arranged at intervals in the circumferential direction; and a coil 18 wound around each tooth 17. The coil 18 generates a magnetic field applied to the rotor 13.

In the present embodiment, for example, 12 teeth 17 and coils 18 are provided. That is, the number of slots of the motor 10 of the present embodiment is 12.

Fig. 3 is a sectional view of the rotor of the present embodiment. In fig. 3, the shaft 20 is not shown. As shown in fig. 2 and 3, rotor 13 includes shaft 20 (see fig. 2), rotor core 30, and a plurality of magnets 50 included in rotor core 30.

Rotor core 30 has a columnar shape extending in the axial direction. Although not shown, for example, the rotor core 30 is configured by stacking a plurality of plate members in the axial direction. As shown in fig. 3, the rotor core 30 includes a fixing hole portion 31, a magnet support hole (through hole) 32, a first protrusion (protruding portion) 37, and a second protrusion (protruding pole portion) 38. Here, the radius R0 of the rotor core 30 is preferably 18.0mm ≦ R0 ≦ 24.0mm, for example.

The fixing hole 31 penetrates the rotor core 30 in the axial direction. The shape of the fixing hole 31 as viewed in the axial direction is a circular shape centered on the central axis J. The fixing hole 31 is through which the shaft 20 (see fig. 2) passes. The inner peripheral surface of the fixing hole 31 is fixed to the outer peripheral surface of the shaft 20. Thereby, rotor core 30 is fixed to shaft 20.

A plurality of magnet support holes 32 are provided at intervals in the circumferential direction in the outer peripheral portion of the rotor core 30. The plurality of magnet support holes 32 are arranged at equal intervals in the circumferential direction. The plurality of magnet support holes 32 are disposed at positions equidistant from the center axis J in the radial direction, and are disposed concentrically. The number of magnet support holes 32 provided in the rotor core 30 is, for example, 5. Fig. 4 is an enlarged cross-sectional view showing a part of the rotor of the present embodiment. The magnet support hole 32 penetrates the rotor core 30 in the axial direction. As shown in fig. 4, the magnet support hole 32 includes: a magnet housing 35 housing a magnet 50; and magnetic flux barriers (gaps) 36 provided at both ends of the magnet housing 35 in the circumferential direction.

The magnet housing 35 has an inner support surface 35a, an outer support surface 35b, and end support surfaces 35c, 35 c. The inner support surface 35a is provided radially inward of the magnet housing 35. The inner support surface 35a is a flat surface perpendicular to the radial direction. The outboard bearing surface 35b is disposed at a radial spacing from the inboard bearing surface 35a and parallel to the inboard bearing surface 35 a. The outer support surface 35b is a flat surface perpendicular to the radial direction. The end support surfaces 35c, 35c extend radially outward from both circumferential ends of the inner support surface 35 a. The circumferential intervals between the plurality of magnet housing portions 35 are, for example, the same. The number of the plurality of magnet housing portions 35 is, for example, 5.

The magnetic flux barriers 36 are provided so as to extend outward of the magnet housing 35 in the circumferential direction from both ends of the magnet housing 35 in the circumferential direction. The flux barriers 36 are located radially outward of the end support surfaces 35c, 35c of the magnet housing 35. Here, for example, the circumferential width dimension w1 of the flux barrier 36 is preferably 1.0mm ≦ w1 ≦ 2.0 mm.

As shown in fig. 3, the first protrusion 37 and the second protrusion 38 are provided on the outer peripheral portion of the rotor core 30. The first protrusion 37 is disposed radially outward of each magnet housing 35. The first projection 37 projects radially outward. The radially outer peripheral surface 37a of the first projection 37 has an arc shape with a radius R1 centered on a point C1 set radially outward of the center axis J when viewed from the axial direction. When viewed from the axial direction, the point C1 is located on a line L1 passing through the center axis J of the rotor core 30 and the center Cm of the magnet housing 35 in the circumferential direction on the line L1. The first protrusion 37 extends continuously from one end portion in the axial direction of the rotor core 30 to the other end portion in the axial direction of the rotor core 30 in the same cross-sectional shape.

Here, for example, the radius of curvature R1 of the outer peripheral surface 37a of the first protrusion 37 is preferably 10.0mm ≦ R1 ≦ 24.0 mm. For example, as shown in fig. 4, it is preferable that a radial dimension T1 between a radially outer side surface 50b of the magnet 50 and an outer peripheral surface 37a of the first protrusion 37 as the outer peripheral surface of the rotor core 30 is 1.8mm ≦ T1 ≦ 2.4 mm.

As shown in fig. 3, the second projecting portion 38 is located between the magnets 50 adjacent to each other in the circumferential direction. The second projecting portion 38 projects radially outward. The radially outer peripheral surface 38a of the second projection 38 has an arc shape with a radius R2 centered on a point C2 set radially outward of the center axis J when viewed axially. When viewed axially, the point C2 is located on a line L2 passing through the center axis J of the rotor core 30 and the circumferential center Cn of the magnets 50 adjacent to each other in the circumferential direction on the line L2. The second protrusion 38 extends continuously from one end portion in the axial direction of the rotor core 30 to the other end portion in the axial direction of the rotor core 30 with the same cross section. For example, the radius of curvature R2 of the outer peripheral surface 38a of the second protrusion 38 is preferably 10.0mm ≦ R2 ≦ 24.0 mm.

As in the present embodiment, the radius of curvature R1 of the outer peripheral surface 37a of the first protrusion 37 is preferably equal to the radius of curvature R2 of the outer peripheral surface 38a of the second protrusion 38 (R1 is equal to R2).

Rotor core 30 has

recesses

39A, 39B.

Recesses

39A, 39B are provided in the outer peripheral portion of rotor core 30.

The recesses 39A are provided on both circumferential sides of the first projection 37, respectively. The concave portion 39A is recessed radially inward from the first projecting portion 37. The recesses 39B are provided on both circumferential sides of the second projecting portion 38, respectively. The concave portion 39B is recessed radially inward from the second projecting portion 38.

Rotor core 30 has a plurality of holes 40 radially outward of fixing hole 31 and radially inward of magnet support hole 32. The plurality of holes 40 are arranged at equal intervals in the circumferential direction. In the present embodiment, 10 holes 40 are provided in the rotor core 30. The plurality of holes 40 are arranged on a line L1 passing through the circumferential center Cm of the magnet housing 35 and on a line L2 passing through the circumferential centers Cn of the

magnet housing

35 and 35 adjacent to each other in the circumferential direction, the line L1 being the line L2. Each hole 40 extends in the axial direction and penetrates rotor core 30 in the axial direction. The hole 40 is curved in an arc shape centering on the central axis J when viewed from the axial direction.

The magnet 50 has a rectangular cross section with a longitudinal direction in the radial direction, and the magnet 50 is a substantially quadrangular prism extending in the axial direction. The magnet 50 is inserted into the magnet housing 35. Thereby, magnet 50 is included in the outer peripheral portion of rotor core 30. Further, each magnet 50 is disposed between the second protrusions 38 adjacent in the circumferential direction. The plurality of magnets 50 are arranged at equal intervals in the circumferential direction. That is, the plurality of magnets 50 are provided at intervals in the circumferential direction around the center axis J. In the present embodiment, the number of magnets 50 provided on the rotor 13 is 5.

As shown in fig. 4, a radially inner side surface 50a of the magnet 50 abuts against an inner support surface 35a of the magnet housing 35. The radially outer side surface 50b of the magnet 50 abuts against the outer support surface 35b of the magnet housing 35. A part of the end surfaces 50c on both sides in the circumferential direction of the magnet 50 abuts on the end supporting surface 35c of the magnet housing 35. The magnet 50 is positioned in the circumferential direction and the radial direction by being housed in the magnet housing portion 35.

The coercive force of the magnet 50 is preferably 1400kA/m or more. The coercive force of the magnet 50 is preferably 1500kA/m or less. The radial thickness T2 of the magnet 50 is preferably 2.6mm or more.

Fig. 5 is a graph showing a relationship between the radial thickness T2 of the magnet 50 and the demagnetization factor in the case where the coercive force of the magnet 50 is made different. As shown by the broken line in fig. 5, the demagnetization factor required of the motor 10 of the present embodiment is, for example, -3%. On the other hand, when the coercive force Hcj of the magnet 50 is 1300kA/m, the required demagnetization factor cannot be satisfied unless the radial thickness T2 of the magnet 50 is 3.4mm or more. On the other hand, when the coercive force Hcj of the magnet 50 is 1400kA/m, the required demagnetization factor can be satisfied by setting the radial thickness T2 of the magnet 50 to 2.6mm or more. When the coercive force Hcj of the magnet 50 is 1600kA/m, the required demagnetization factor can be satisfied even if the radial thickness T2 is 2.0 mm. However, generally, when the coercive force Hcj exceeds 1500kA/m, the magnet 50 becomes expensive, resulting in an increase in the cost of the motor 10. Therefore, as described above, the coercive force of the magnet 50 is preferably 1400kA/m or more and 1500kA/m or less.

The radial thickness T2 of the magnet 50 is preferably 3.0mm or less. Fig. 6 is a graph showing a change in the proportion of the induced voltage per unit volume when the radial thickness T2 of the magnet 50 is made different. As shown in fig. 6, the larger the radial thickness T2 of the magnet 50, the smaller the proportion of the induced voltage per unit volume. That is, the larger the radial thickness T2 of the magnet 50 is, the lower the efficiency of generating the induced voltage in the magnet 50 is. Further, the larger the thickness T2 of the magnet 50 is, the more the amount of material used for the magnet 50 increases, which leads to an increase in cost. Therefore, as described above, the thickness T2 of the magnet 50 is preferably 3.0mm or less.

Fig. 7 is a diagram showing a configuration of a full-magnet rotor 100 to be compared with the rotor 13 of the present embodiment. The full-magnet rotor 100 includes a plurality of magnets 102 spaced apart from each other in the circumferential direction on the outer periphery of a rotor core 101. The plurality of magnets 102 includes a magnet 102N and a magnet 102S, and the magnet 102N and the magnet 102S have different magnetic poles from each other. Magnets 102N and magnets 102S are alternately arranged in the circumferential direction of rotor core 101. Here, the magnet 102N is disposed at a position of the rotor 13 in the present embodiment where the magnet 50 is replaced. The magnet 102S is disposed at a position of the rotor 13 replaced with the second projection 38 in the present embodiment. Here, in the full-magnet rotor 100, the demagnetization resistance is 100% in the following cases: the coercive force of each of the magnet 102N and the magnet 102S was 1250kA/m, and the radial thickness T2 of the magnet 102N and the magnet 102S was 2 mm. In the rotor 13 of the present embodiment as shown in fig. 1 to 4, if it is desired to obtain demagnetization resistance equivalent to that of the full-magnet rotor 100, the coercive force of each magnet 50 needs to be 1400kA/m or more. That is, in the rotor 13 of the alternating motor 10, the coercive force of the magnet 50 is 112% or more of the coercive force of the

magnets

102N and 102S of the full-magnet rotor 100.

As shown in fig. 4, the radial thickness T2 of the magnet 50 is preferably smaller than the thickness T1, and the thickness T1 is preferably the radial thickness between the radially outer side surface 50b of the magnet 50 and the outer peripheral surface of the rotor core 30. Further, the width W2 of the magnet 50 in the direction perpendicular to the radial direction is preferably 11.0 ≦ W2 ≦ 12.5.

As described above, the rotor 13 of the present embodiment has 10 magnetic poles each including the magnet 50 and the second protrusion 38.

According to the present embodiment, in the rotor 13 of the alternating motor 10, the coercive force of the magnet 50 is 1400kA/m or more, and the radial thickness T2 of the magnet 50 is 2.6mm or more. Accordingly, the rotor 13 and the motor 10 can ensure the same demagnetization resistance as the full-magnet rotor 100, and the number of magnets 50 can be reduced as compared with the full-magnet rotor 100. Therefore, the rotor 13 and the motor 10 are provided, which can suppress the cost of the magnet 50 and can suppress an increase in the demagnetization factor.

In the rotor 13 of the present embodiment, the coercive force of the magnet 50 is 112% or more of the coercive force of the

magnets

102N and 102S of the full-magnet type, as compared with the rotor 100 of the full-magnet type in which the

magnets

102N and 102S of different magnetic poles are alternately arranged in the circumferential direction of the rotor core 101 as shown in fig. 7. This provides the rotor 13 and the motor 10 that can suppress an increase in the demagnetization factor while suppressing the cost of the magnet 50.

According to the present embodiment, the coercive force of the magnet 50 is 1500kA/m or less. A magnet of 1500kA/m or less can be produced at a relatively low cost. This can suppress the cost increase of the magnet 50.

According to the present embodiment, the radial thickness T2 of the magnet 50 is 3.0mm or less. This can suppress a decrease in efficiency (induced voltage/volume) of the magnet 50 and suppress the amount of material used for the magnet 50, thereby reducing the cost.

According to the present embodiment, the magnetic flux barriers 36 are provided at both ends of the magnet housing portion 35 in the circumferential direction. The circumferential width dimension w1 of the flux barrier 36 is 1.0mm ≦ w1 ≦ 2.0 mm. This prevents the magnetic flux flowing between stator 12 and magnet 50 from diffusing, and thus allows the magnetic flux to flow smoothly.

According to the present embodiment, the first projection 37 and the second projection 38 are provided with

recesses

39A and 39B recessed inward in the radial direction on both sides in the circumferential direction. This prevents the magnetic flux flowing between stator 12 and magnet 50 from diffusing, and thus allows the magnetic flux to flow smoothly.

According to the present embodiment, radial thickness T2 of magnet 50 is smaller than radial thickness (dimension) T1 between radially outer side surface 50b of magnet 50 and the outer peripheral surface of rotor core 30. Further, a radial dimension T1 between the radially outer side surface 50b of the magnet 50 and the outer peripheral surface of the rotor core 30 is 1.8mm ≦ T1 ≦ 2.4 mm. This allows the magnet 50 to be held in the magnet housing 35 and to be closer to the stator 12. Therefore, leakage of magnetic flux to the outside between the magnet 50 and the teeth 17 is suppressed.

According to the present embodiment, the width dimension w2 of the magnet 50 in the direction perpendicular to the radial direction is 11.0 ≦ w2 ≦ 12.5. The radius R0 of the rotor core 30 is 18.0mm ≦ R0 ≦ 24.0mm, and the radius R2 of curvature of the outer peripheral surface 38a of the second protrusion 38 is 10.0mm ≦ R2 ≦ 24.0 mm. The radius of curvature R1 of the outer peripheral surface 37a of the first protrusion 37 is 10.0mm ≦ R1 ≦ 24.0 mm. Such a rotor 13 can suppress an increase in the demagnetization factor while suppressing the cost of the magnet 50.

According to the present embodiment, the rotor 13 has 10 magnetic poles each including the magnet 50 and the second protrusion 38, and the stator 12 has 12 slots of the coil 18 for applying a magnetic field to the rotor 13. This can suppress an increase in the demagnetization factor while suppressing the cost of the magnet 50.

While one embodiment of the present invention has been described above, the configurations and combinations thereof of the embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations can be made without departing from the spirit of the present invention. The present invention is not limited to the embodiments.

For example, the use of the motor having the rotor according to the above embodiment and the modifications thereof is not particularly limited.

Claims

1. A rotor of an alternating motor, wherein,

the rotor has:

a shaft that rotates around a central axis extending in the vertical direction;

a rotor core fixed to the shaft; and

a plurality of magnets included in the rotor core and arranged at intervals in a circumferential direction around the center axis,

the rotor core is provided with salient pole portions that protrude radially outward around the center axis between the magnets adjacent to each other in the circumferential direction,

the coercive force of the magnet is more than 1400kA/m,

the radial thickness of the magnet is more than 2.6mm,

only the 1 st recesses recessed toward the radially inner side are provided on both sides in the circumferential direction of the salient pole portion,

the rotor core has a protruding portion protruding radially outward of the magnet, and 2 nd recessed portions recessed radially inward are provided only at circumferential ends of the protruding portion.

2. The rotor of claim 1,

the coercive force of the magnet of the rotor is 112% or more of the coercive force of a full-magnet type magnet, as compared with a full-magnet type rotor in which magnets having different magnetic poles are alternately arranged in the circumferential direction of a rotor core.

3. The rotor of claim 1 or 2,

the coercive force of the magnet is less than 1500 kA/m.

4. The rotor of claim 1 or 2,

the radial thickness of the magnet is less than 3.0 mm.

5. The rotor of claim 1 or 2,

the rotor core is provided with a through hole into which the magnet is inserted,

gaps are provided at both circumferential ends of the through-hole.

6. The rotor of claim 5,

the circumferential width dimension w1 of the void is 1.0mm ≦ w1 ≦ 2.0 mm.

7. The rotor of claim 1 or 2,

the radial thickness of the magnet is smaller than the radial dimension between the radially outer side surface of the magnet and the outer peripheral surface of the rotor core.

8. The rotor of claim 1 or 2,

a radial dimension T1 between a radially outer side surface of the magnet and the outer peripheral surface of the rotor core is 1.8mm ≦ T1 ≦ 2.4 mm.

9. The rotor of claim 1 or 2,

the width W2 of the magnet in the direction perpendicular to the radial direction is 11.0mm ≦ W2 ≦ 12.5 mm.

10. The rotor of claim 1 or 2,

the radius R0 of the rotor core is 18.0mm ≦ R0 ≦ 24.0mm,

the curvature radius R2 of the outer peripheral surface of the salient pole part is 10.0mm ≦ R2 ≦ 24.0 mm.

11. The rotor of claim 1 or 2,

the radius of curvature R1 of the outer peripheral surface of the protrusion is 10.0mm ≦ R1 ≦ 24.0 mm.

12. A motor, comprising:

the rotor of any one of claims 1 to 11; and

a stator facing the rotor with a gap in a radial direction,

the rotor has 10 magnetic poles constituted by the magnets and the salient pole portions,

the stator has 12 slots of coils that apply a magnetic field to the rotor.