CN110797998B

CN110797998B - Rotor and motor

Info

Publication number: CN110797998B
Application number: CN201910706546.1A
Authority: CN
Inventors: 田中邦明
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2018-08-03
Filing date: 2019-08-01
Publication date: 2022-02-08
Anticipated expiration: 2039-08-01
Also published as: CN110797998A; JP2020022328A

Abstract

The invention provides a rotor and a motor. The rotor is 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; a plurality of magnets disposed on a surface of the rotor core and provided at intervals in a circumferential direction around the center axis; and a cover member that holds the magnet on the surface of the rotor core, the rotor core including: a plurality of salient pole portions provided so as to protrude radially outward with respect to the center axis between the circumferentially adjacent magnets; and a plurality of recesses that are respectively located on both sides of each salient pole portion in the circumferential direction and that are recessed inward in the radial direction, wherein the cover member is made of a magnetic material, and presses each of the magnets to the rotor core inward in the radial direction between the salient pole portions adjacent to each other in the circumferential direction of the rotor core.

Description

Rotor and motor

Technical Field

The invention relates to a rotor and a motor.

Background

In general, an alternating rotor has a bridge portion connecting between a real pole portion (magnetic pole formed by a magnet) and a pseudo pole portion (magnetic pole formed by an iron core). Patent document 1 discloses an alternating rotor having bridges. However, in the case of the bridge portion, the leakage magnetic flux is increased and the magnetic flux contributing to the torque is reduced, as compared with the case of the absence of the bridge portion.

For example, in the case of a rotor core including an electromagnetic steel plate having a bridge portion and an electromagnetic steel plate not having a bridge portion, although the leakage path of magnetic flux is reduced, the generation of leakage magnetic flux from the bridge portion cannot be avoided. Further, even if the thickness of the bridge portion is intended to be reduced, the minimum thickness of the bridge portion depends on the plate thickness, and therefore it is difficult to reduce the thickness by a certain amount or more.

On the other hand, in the IPM structure, a structure for holding the magnet in the rotor core is required in the case where there is no bridge portion. Patent document 2 discloses a structure in which a magnet is held by a cover member or a resin cover made of a non-magnetic metal material.

Patent document 1: japanese laid-open patent publication No. 2012-29405

Patent document 2: japanese patent laid-open publication No. 2010-252554

However, in the case of patent document 2, since the magnet is held by the cover of the non-magnetic member, there is a concern that the air gap becomes wide and the torque is reduced.

Disclosure of Invention

In view of the above problems, an object of one embodiment of the present invention is to provide a rotor and a motor capable of improving torque while suppressing a decrease in magnetic flux characteristics.

One aspect of the rotor according to the present invention is a rotor of an alternating motor, the rotor including: a shaft that rotates around a central axis extending in the vertical direction; a rotor core fixed to the shaft; a plurality of magnets disposed on a surface of the rotor core and provided at intervals in a circumferential direction around the center axis; and a cover member that holds the magnet on the surface of the rotor core, the rotor core including: a plurality of salient pole portions provided so as to protrude radially outward with respect to the center axis between the circumferentially adjacent magnets; and a plurality of recesses that are respectively located on both sides of each salient pole portion in the circumferential direction and that are recessed inward in the radial direction, wherein the cover member is made of a magnetic material, and presses each of the magnets to the rotor core inward in the radial direction between the salient pole portions adjacent to each other in the circumferential direction of the rotor core.

One embodiment of the motor of the present invention includes the rotor and a stator facing the rotor with a gap in a radial direction.

According to one embodiment of the present invention, a rotor and a motor capable of preventing leakage of magnetic flux and improving torque in a structure without a bridge portion can be provided.

Drawings

Fig. 1 is a schematic sectional view of a motor according to an embodiment, which is a sectional view taken along line a-a of fig. 2.

Fig. 2 is a cross-sectional view of an embodiment of a motor.

Fig. 3 is a view of the rotor according to the embodiment as viewed from the axial side.

Fig. 4 is a perspective view of the cover member of one embodiment (in a state before caulking).

Fig. 5 is a graph comparing performance of motors having different configurations of rotor cores.

Description of the reference symbols

10: a motor; 10: motors (alternating type motors); 12: a stator; 13: a rotor; 19: a cover member; 20: a shaft; 21: a main body portion; 22: a holding piece portion; 22 b: an outer peripheral surface (surface) of the holding piece portion; 30: a rotor core; 30 a: an end face; 37: an iron core portion; 37 b: an outer peripheral surface (surface) of the core portion; 38: a salient pole portion; 38 a: the outer peripheral surface (surface) of the salient pole portion; 39: a recess; 50: a magnet; 50 b: the outer surface (surface) of the magnet; j: a central axis; r 1: a maximum dimension from the central axis to a surface radially outward of the tab portion; r 2: a maximum dimension from the central axis to a radially outer surface of the core portion; r 3: a maximum dimension from the central axis to a surface radially outward of the holding tab portion; t: the thickness of the holding piece portion.

Detailed Description

Hereinafter, a rotor and a motor according to an embodiment of the present invention will be described with reference to the drawings. The scope of the present invention is not limited to the following embodiments, and may be arbitrarily changed within the scope of the technical idea of the present invention. In the drawings below, in order to facilitate understanding of each structure, the actual structure may be different from the scale, the number, or the like of each structure.

In addition, in the drawings, an XYZ coordinate system is appropriately shown as a three-dimensional rectangular coordinate system. In the XYZ coordinate system, the Z-axis direction is a direction parallel to the axial direction of the central axis J shown in fig. 1. The X-axis direction is a direction perpendicular to the Z-axis direction and is the left-right direction in fig. 1. The Y-axis direction is a direction perpendicular to both the X-axis direction and the Z-axis direction.

Unless otherwise specified, a direction parallel to the central axis J (Z-axis direction) is simply referred to as "axial direction", a radial direction about the central axis J is simply referred to as "radial direction", and a circumferential direction about the central axis J, that is, a direction around the central axis J is simply referred to as "circumferential direction".

Fig. 1 is a schematic cross-sectional view of a motor 10 according to the present embodiment, and is a cross-sectional view taken along line a-a of fig. 2. Fig. 2 is a cross-sectional view of the motor 10 of the present embodiment, the cross-sectional view intersecting the axial direction. Fig. 3 is a view of the rotor 13 of the present embodiment as viewed from the axial side (+ Z).

As shown in fig. 1, the motor 10 is an alternating type motor. The motor 10 has: a housing 11; a stator 12; a rotor 13 having a shaft 20 disposed along a central axis J extending in the vertical direction; a bearing holder 14; and

bearings

15, 16. The shaft 20 is rotatably supported by the

bearings

15 and 16. The shaft 20 is cylindrical extending in a direction along the center axis J. The housing 11 is a cylindrical member. The housing 11 accommodates therein the rotor 13, the stator 12, the bearing holder 14, and the

bearings

15 and 16. The bearing holder 14 is a plate-like member and is directly or indirectly fixed to the housing 11. The

bearings

15 and 16 are, for example, ball bearings. The bearing 15 is held by the bearing holder 14. The bearing 15 is held at a lower portion in the axial direction of the housing 11.

As shown in fig. 2, the stator 12 is opposed to the rotor 13 at a radial outer side of the rotor 13 with a gap in the radial direction. The stator 12 has a plurality of teeth 17 provided at intervals in the circumferential direction and a coil 18 wound around each tooth 17. The teeth 17 are radially opposed to the rotor 13. The coil 18 generates a magnetic field applied to the rotor 13.

In the present embodiment, for example, 12

teeth

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

As shown in fig. 2 and 3, the rotor 13 includes a shaft 20 (see fig. 2), a rotor core 30, a plurality of magnets 50, a plurality of core portions 37, and a cover member 19.

Rotor core 30 is a columnar shape extending in the axial direction. Although not shown, rotor core 30 is formed by stacking a plurality of plate members in the axial direction, for example. The plate member is, for example, an electromagnetic steel plate or the like. As shown in fig. 3, rotor core 30 includes fixing hole 31, fixing portion 32, a plurality of magnet housing portions 35, a plurality of salient pole portions 38, and a plurality of recessed portions 39.

As shown in fig. 3, the fixing portion 32 has a cylindrical shape coaxial with the central axis J, and protrudes axially outward from an end surface 30a on one axial side of the rotor core 30 (see fig. 1).

The fixing hole 31 is located at the substantial center of the rotor core 30 and penetrates the fixing portion 32 in the axial direction. The shape of the fixing hole 31 as viewed in the axial direction is a substantially circular shape centered on the central axis J. The shaft 20 passes through the fixing hole portion 31. The inner peripheral surface 31a of the fixing hole 31 is fixed to the outer peripheral surface 20a of the shaft 20. Thereby, rotor core 30 is fixed to shaft 20.

The shaft 20 may be indirectly fixed to the fixing hole 31 through a resin, a metal material, or the like.

The magnet housing 35 houses the magnet 50. The plurality of magnet housing portions 35 are provided at intervals in the circumferential direction on the outer circumferential surface of the rotor core 30. The plurality of magnet housing portions 35 are arranged at equal intervals in the circumferential direction. The plurality of magnet housing portions 35 are provided at positions equidistant from the center axis J in the radial direction, and are arranged in a so-called concentric manner. The number of the magnet housing portions 35 provided in the rotor core 30 is five, for example.

The magnet housing 35 extends in the axial direction. The magnet housing 35 is formed of a recess recessed radially inward from the outer peripheral surface of the rotor core 30, and includes an inner support surface 35a and side support surfaces 35c and 35 c. The inner support surface 35a is a flat surface perpendicular to the radial direction and along the axial direction, and constitutes a bottom portion of the magnet housing portion 35. The side support surfaces 35c, 35c are provided on both circumferential sides of the inner support surface 35a, and constitute side portions on both circumferential sides of the magnet housing portion 35.

The salient pole portions 38 are located between the magnet housing portions 35 adjacent to each other in the circumferential direction. The projecting pole portion 38 projects radially outward. The radially outer peripheral surface 38a of the projecting pole portion 38 is arcuate with a predetermined curvature radius R1 (not shown). The salient pole portions 38 extend 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 section.

The recesses 39 are located on both sides of the projecting pole portion 38 and the magnet housing portion 35 in the circumferential direction, and are provided between the projecting pole portion 38 and the magnet housing portion 35 in the circumferential direction. The recess 39 is a portion recessed toward the radially inner side. The recess 39 communicates with the air gap 16 formed between the stator 12 and the rotor 13 shown in fig. 1.

Rotor core 30 has a plurality of holes 40 radially outside of fixing hole 31 and radially inside of magnet housing 35. The plurality of holes 40 are arranged at equal intervals in the circumferential direction. Rotor core 30 is provided with, for example, 10 holes 40. Each hole 40 extends in the axial direction and penetrates rotor core 30 in the axial direction. The plurality of holes 40 contribute to weight reduction of the rotor core 30 and also function as a guide for magnetic flux.

The cross section of the magnet 50 as viewed in the axial direction is a substantially rectangular shape having a longitudinal direction in the circumferential direction, and is a substantially quadrangular prism extending in the axial direction. The plurality of magnets 50 are housed in the respective magnet housing portions 35 provided at intervals in the circumferential direction. Thereby, the magnets 50 are arranged between the salient pole portions 38 adjacent in the circumferential direction.

The radially inner surface 50a of the magnet 50 contacts the inner support surface (surface of the rotor core 30) 35a of the magnet housing 35. End surfaces 50c, 50c on both sides in the circumferential direction of the magnet 50 are partially in contact with side support surfaces 35c, 35c of the magnet housing 35. The magnet 50 is accommodated in the magnet accommodating portion 35 so as to be positioned in the circumferential direction and the radial direction. The end face 50c of the magnet 50 has an outer peripheral end face 50d located radially outward of the side support face 35 c. The outer peripheral end surface 50d is exposed from the magnet housing portion 35 to the recess 39.

The core portion 37 is made of the same material as the rotor core 30, but is not an integral component with the rotor core 30 but a separate component. A plurality of core portions 37 are disposed radially outward of the magnets 50 housed in the magnet housing portions 35. The inner end surface 37a of the core portion 37 is a flat surface perpendicular to the radial direction, and contacts the outer surface (surface) 50b of the magnet 50.

When the rotor core 30 is formed of an electromagnetic steel sheet, it is desirable that the core portion 37 and the rotor core 30 be formed of the same electromagnetic steel sheet by press working or the like. This enables the magnetic flux to smoothly flow between rotor core 30 and core portion 37.

The radially outer surface 37b of the core portion 37 is arcuate with a predetermined radius of curvature R2 (not shown) when viewed from the axial direction. The radius of curvature R2 of the outer surface 37b is smaller than the radius of curvature R1 of the outer peripheral surface 38a of the above-described projecting pole portion 38 (R2 < R1). The core portion 37 extends continuously from one end side to the other end side in the axial direction in the same sectional shape.

As shown in fig. 2, a dimension (thickness) T1 in the radial direction of the core portion 37 is smaller than a dimension (thickness) T2 in the radial direction of the magnet 50. This allows magnet 50 to be brought close to stator 12.

In the rotor 13 of the present embodiment, the core portions 37 and the magnets 50 as the real pole portions and the salient pole portions 38 as the dummy pole portions alternate in the circumferential direction around the central axis J. The magnetic poles of the core portion 37 and the salient pole portion 38 are different from each other. In the following description, the core portion 37 and the magnet 50 are sometimes referred to as "real pole portion", and the salient pole portion 38 is sometimes referred to as "pseudo pole portion".

In the rotor 13, it is desirable that the salient pole portions 38 as the pseudo pole portions are located at positions 180 degrees apart from the core portion 37 as the solid pole portion and the magnet 50 with respect to the center axis J. That is, it is desirable that the "real pole portions" and the "dummy pole portions" are not opposed to each other in the radial direction with the center axis J interposed therebetween. When the "real pole portions" and the "pseudo pole portions" are located at positions (positions different by 180 degrees) facing each other in the radial direction with respect to the central axis J, there is a possibility that the "real pole portions" or the "pseudo pole portions" facing each other are magnetically attracted to each other to generate vibration. However, in the present embodiment, the "real pole portions" and the "dummy pole portions" do not radially face each other across the center axis J. Therefore, vibration due to the magnetic action between the same kind of pole portions can be suppressed.

Fig. 4 is a perspective view showing the structure of the cover member 19, and shows a state before being attached to the rotor core 30 and the shaft 20.

The cover member 19 is directly or indirectly fixed to the shaft 20, and at least a part thereof is disposed radially outside the rotor core 30. As shown in fig. 1 and 3, the cover member 19 of the present embodiment is fixed to the shaft 20 via the rotor core 30.

In the present specification, "directly fixed" means that two members are fixed to each other without interposing other members therebetween. The term "indirectly fixed" means that two members are fixed to each other with another member interposed therebetween.

The cover member 19 is made of a magnetic material. The cover member 19 is made of a metal material such as an electromagnetic steel plate or steel. However, the material of the cover member 19 is not particularly limited as long as it is a material having magnetic properties.

In the cover member 19, the following configuration is adopted: the cover member 19 has a function of holding the magnets 50 and the core portions 37 on the outer peripheral surface of the rotor core 30 by pressing the core portions 37 and the magnets 50 radially inward between the salient pole portions 38 adjacent to each other in the circumferential direction of the rotor core 30.

The cover member 19 includes a plurality of holding pieces 22 and a body 21 connecting the plurality of holding pieces 22.

As shown in fig. 1 and 3, main body 21 covers at least a portion of one axial end face 30a of rotor core 30. The body 21 has a circular fixing hole 23 in the center thereof about the central axis J. The fixing portion 32 of the rotor core 30 and the shaft 20 (see fig. 2) pass through the fixing hole 23. As shown in fig. 3 and 4, the inner peripheral surface 23a of the fixing hole 23 is fixed to the outer peripheral surface 32a of the fixing portion 32 of the rotor core 30. Thus, the cover member 19 is fixed to the shaft 20 via the rotor core 30.

As shown in fig. 4, the main body portion 21 is constituted by: an annular portion 24 constituting the fixing hole 23; and a plurality of projecting portions 25 extending radially outward from the outer peripheral portion of the annular portion 24. The plurality of protruding portions 25 are present at equal intervals in the circumferential direction of the annular portion 24. The arrangement intervals of the plurality of protruding portions 25 are equal to the arrangement intervals of the plurality of core portions 37 arranged at intervals in the circumferential direction of the rotor core 30.

In the present embodiment, as shown in fig. 3, the extension portion 25 has a size covering substantially the entire end surfaces 37e and 50e of the core portion 37 and the magnet 50 on one side in the axial direction when viewed in the axial direction, but is not limited thereto.

The protruding portion 25 is formed in a shape in which

side portions

25c and 25c on both sides in the circumferential direction extend in the radial direction and expand in a fan shape as going outward in the radial direction when viewed in the axial direction. The shape of the protruding portion 25 is not limited to this, and may be other shapes as long as the magnet 50 and the core portion 37 can be held, for example. For example, in order to reduce the leakage path of the magnetic flux, the extension portion 25 may be provided with a hole penetrating in the thickness direction thereof.

As shown in fig. 3 and 4, the plurality of holding pieces 22 extend in the axial direction from the radially outer end of each of the projecting portions 25. The holding piece 22 extends continuously from one end side to the other end side in the axial direction in the same sectional shape.

The holding piece portion 22 has a size covering the outer surface 37b of the iron core portion 37. In the present embodiment, for example, the width W2 in the circumferential direction of the holding piece portion 22 is substantially the same as the width W1 in the circumferential direction of the core portion 37 described above, but the present invention is not necessarily limited thereto.

Each holding piece 22 faces the plurality of core portions 37 arranged in the circumferential direction. As shown in fig. 3, the inner peripheral surface 22a of each holding piece 22 preferably makes surface contact with substantially the entire outer surface 37b of the core 37.

As shown in fig. 4, the tip end portion 22c (the end portion opposite to the main body portion 21 in the axial direction) of each holding piece portion 22 is bent radially inward at a predetermined position (the position indicated by the one-dot chain line in fig. 4) in the axial direction, and is caulked to the end surface 30b of the rotor core 30 as shown in fig. 1.

The holding pieces 22 press the core portions 37 and the magnets 50 radially inward, and the plurality of core portions 37 and the plurality of magnets 50 are held on the outer peripheral surface of the rotor core 30.

This prevents the plurality of core portions 37 and the plurality of magnets 50 from being displaced in the axial direction, and thus, they can be firmly fixed to the rotor core 30. In addition, the effect of holding the laminated steel plates of the rotor core 30 is also obtained. Further, the cover member 19 may also be used to caulk the laminated steel plates.

In the present embodiment, the maximum dimension r1 from the center axis J to the radially outer peripheral surface (surface) 38a of the salient pole portion 38 is larger than the maximum dimension r2 from the center axis J to the radially outer peripheral surface (surface) 37b of the core portion 37.

In the present specification, the "maximum dimension" refers to a distance from the central axis J to the farthest point in the outer peripheral surface of each member in the radial direction.

The maximum dimension r1 is equal to a maximum dimension r3 from the central axis J to the outer peripheral surface (surface) 22b of the cover member 19 on the radially outer side of the holding piece 22. That is, the outermost end of the outer peripheral surface 22b of the holding piece 22 of the cover member 19 is located at the same position as the outermost end of the outer peripheral surface 38a of the projecting portion 38 in the radial direction. Therefore, as shown in fig. 2, the air gap S2 between the tooth 17 and the projecting portion 38 is the same as the air gap S1 between the tooth 17 and the core portion 37 in the radial direction (S2 is equal to S1).

As shown in fig. 1 and 3, the radial dimension of the holding piece 22 of the cover member 19, that is, the difference between the thickness t and the maximum dimension r3 of the holding piece 22 and the maximum dimension r2 is equal.

In the rotor 13 of the present embodiment, there is no bridge portion connecting the core portion 37 and the salient-pole portion 38. In addition, the cover member 19 that holds the core portion 37 and the magnet 50 is also provided with holding pieces 22 that press the core portion 37 and the magnet 50 radially inward at intervals in the circumferential direction.

Therefore, the magnetic flux flowing through rotor core 30 can be prevented from leaking to a position other than between core portion 37 and teeth 17. That is, since the core portion 37, the salient pole portions 38, and the holding piece portions 22 are circumferentially separated from each other, the magnetic flux generated between the core portion 37 of the rotor core 30 and the stator 12 can be prevented from leaking to the salient pole portions 38. As a result, the torque generated by the motor 10 can be increased as compared with the case where the bridge portion is provided.

Fig. 5 is a graph comparing the performance of motors having different rotor core structures (with or without bridge portions). In fig. 5, the torque value in the case where the bridge is present is indicated by a broken line B, and the torque value in the case where the bridge is absent is indicated by a solid line S. As shown in fig. 5, when the rotor core has the bridge portion structure, a torque value of 4.5Nm or more is not obtained. On the other hand, in the case of the structure having the rotor core 30 without the bridge portion, a torque value of 5.2Nm or more is obtained. That is, the torque value is improved by about 16.9% in the structure without the bridge portion, as compared with the case with the bridge portion. Thus, the absence of the bridge reduces leakage of magnetic flux due to the bridge, thereby improving torque.

As described above, in the present embodiment, the bridge portion is not provided, the leakage of the magnetic flux is suppressed, the torque is improved, and the cover member 19 solves the problem of the holding structure of the magnet 50 and the core portion 37 due to the absence of the bridge portion.

According to the present embodiment, the cover member 19 is made of a magnetic material and is in surface contact with the outer surface 37b of the core 37. Therefore, the holding piece 22 of the cover member 19 functions as a part of the core portion 37, and the magnetic flux generated from the magnet 50 passes through the entire boundary between the core portion 37 and the holding piece 22. As a result, the magnetic flux can be stably generated radially outward from the outer peripheral surface 22b of the holding piece portion 22. Further, since the holding piece portion 22 functions as a part of the core portion 37, the radial distance (air gap) between the core portion and the teeth 17 can be substantially reduced.

In the present embodiment, the core portion 37 is interposed between the holding piece portion 22 of the cover member 19 and the magnet 50 in the radial direction. However, since the holding piece portion 22 functions as the core portion as described above, the core portion 37 may be omitted by making the radial thickness of the holding piece portion 22 large enough to serve as the core portion. That is, the cover member 19 may be directly pressed against the magnet 50 by directly contacting the magnet 50. More specifically, the holding piece 22 of the cover member 19 may be directly brought into contact with the magnet 50 to directly press the magnet 50 radially inward. However, the cover member 19 having the holding piece portion 22 having a sufficiently large thickness dimension in the radial direction is expensive. That is, the rotor 13 of the present embodiment has the core portion 37 interposed between the holding piece portion 22 and the magnet 50 in the radial direction, and thus can reduce the manufacturing cost.

In the present embodiment, the core portion 37 and the magnet 50 are pressed radially inward by the holding pieces 22 of the cover member 19, and are firmly held by the rotor core 30. This eliminates the need for an adhesive between core portion 37, magnet 50, and rotor core 30, and prevents magnet 50 and core portion 37 from being displaced from rotor core 30 by centrifugal force when rotor 13 rotates at high speed.

In the present embodiment, the end surface of the rotor core 30 on one axial side is exposed from between the circumferentially adjacent protruding portions 25 of the cover member 19, and the end surface on the other axial end side is exposed from between the distal end portions 22c of the circumferentially adjacent holding piece portions 22. Therefore, leakage magnetic flux can be suppressed also on both sides of the rotor 13 in the axial direction.

In the present embodiment, the outer peripheral surface 38a of the salient-pole portion 38 of the rotor core 30 and the outer peripheral surface 22b of the holding piece portion 22 of the cover member 19 are located at the same position in the radial direction. Since no step is formed between the salient-pole portions 38 and the holding-piece portions 22, the radial gap between the rotor 13 and the stator 12 can be made constant, and the radial electromagnetic force (radial force) between the rotor 13 and the stator 12 can be made uniformly close to the holding-piece portions 22 (core portions 37) of the cover member 19 and the salient-pole portions 38 of the rotor core 30. As a result, torque ripple or cogging torque can be reduced, and vibration and noise generated in the motor 10 can be reduced.

In the present embodiment, at least a part of the magnet 50 is exposed in the recess 39 of the rotor core 30, so that the flow of magnetic flux between the core portion 37 and the stator 12 can be made smooth, and the torque can be increased.

While the embodiment and the modified examples of the present invention have been described above, the respective configurations and combinations thereof in the embodiment are examples, and additions, omissions, substitutions, and other modifications of the configurations may 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-described embodiment and the modifications thereof is not particularly limited. The motor having the rotor according to the above-described embodiment and the modifications thereof is mounted on, for example, an electric pump, an electric power steering, and the like.

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;

a plurality of magnets disposed on a surface of the rotor core and provided at intervals in a circumferential direction around the center axis; and

a cover member that holds the magnet to the surface of the rotor core,

the rotor core has:

a plurality of salient pole portions provided so as to protrude radially outward with respect to the center axis between the circumferentially adjacent magnets; and

a plurality of recessed portions which are respectively located on both sides of each projecting pole portion in the circumferential direction and are recessed toward the radially inner side,

the cover member is made of a magnetic material, and presses the magnets toward a radially inner side to the rotor core between the salient pole portions adjacent to each other in a circumferential direction of the rotor core,

the cover member has:

a plurality of holding pieces provided at intervals around the central axis and pressing the magnets radially inward, respectively; and

a body portion that covers at least a part of an end surface on one axial side of the rotor core and connects the plurality of holding pieces together,

the plurality of holding pieces are provided at positions facing the magnets.

2. The rotor of claim 1,

the main body portion has:

an annular portion having a fixing hole through which the shaft passes; and

a plurality of projecting portions extending radially outward from an outer peripheral portion of the annular portion,

the holding piece portion extends in the axial direction from an end portion of the radially outer side of the protruding portion.

3. The rotor of claim 1 or 2,

a core portion is provided on a radially outer surface of the magnet.

4. The rotor of claim 1 or 2,

the holding piece portion presses the magnet to the rotor core radially inward via the core portion.

5. The rotor of claim 1 or 2,

the holding piece portion directly contacts the magnet and presses the magnet to the rotor core toward a radially inner side.

6. The rotor of claim 3,

a maximum dimension r1 from the center axis to a radially outer surface of the tab portion is larger than a maximum dimension r2 from the center axis to a radially outer surface of the core portion, the maximum dimension r1 being equal to a maximum dimension r3 from the center axis to a radially outer surface of the holding tab portion.

7. The rotor of claim 6,

the dimension in the radial direction of the holding piece portion is equal to the difference between the maximum dimension r2 and the maximum dimension r 3.

8. The rotor of claim 1 or 2,

at least a part of the magnet is exposed to the recess.

9. The rotor of claim 1 or 2,

the magnet and the salient pole portion are opposed to each other in a radial direction with the central axis therebetween.

10. A motor, wherein,

the motor has:

the rotor of any one of claims 1 to 9; and

and a stator facing the rotor with a gap in a radial direction.