CN116806407A

CN116806407A - Rotary electric machine

Info

Publication number: CN116806407A
Application number: CN202180093133.6A
Authority: CN
Inventors: 绵引正伦
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2021-02-10
Filing date: 2021-06-09
Publication date: 2023-09-26
Also published as: TW202232863A; WO2022172478A1

Abstract

The present invention provides a rotary electric machine, which at least comprises a pair of first magnets, wherein the first magnets are arranged at intervals in the circumferential direction, and extend along the direction of separating from each other in the circumferential direction along the radial direction from the inner side to the outer side in the radial direction when seen along the axial direction. The pair of first magnets forms a pole, and a plurality of magnets are arranged along the circumferential direction with the q-axis interposed therebetween. The rotor core has a hole portion penetrating in the axial direction at a q-axis position in the circumferential direction as viewed in the axial direction. At least a part of the hole portion is located radially outward of the pair of first magnets.

Description

Rotary electric machine

Technical Field

The present invention relates to a rotating electrical machine.

Background

Rotary electric machines such as an embedded magnet synchronous motor (IPMSM) having a rotor core and permanent magnets disposed in holes provided in the rotor core are known. In such a rotary electric machine, measures such as providing grooves, protrusions, slits, holes, and the like in the rotor core, measures such as the size and material of the magnet itself, and measures such as measures against temperature changes of the magnet are adopted as measures against demagnetization. For example, patent document 1 discloses a rotary electric machine in which permanent magnets are arranged in a V shape, and first and second magnet portions having magnetization directions intersecting each other inside the magnets are arranged in two groups of magnet portions constituting the V shape, respectively, to suppress demagnetization of the magnets.

In the rotating electrical machine, low vibration and low noise are required. For this reason, as a technique for changing the shape of the vicinity of the air gap having a high degree of contribution to the electromagnetic exciting force acting between the rotor and the stator of the exciting motor, for example, patent document 2 discloses that a flux barrier penetrating in the axial direction is provided between magnets adjacent to each other with the q-axis interposed therebetween.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open publication No. 2019-30206

Patent document 2: japanese patent laid-open publication No. 2019-122233

Disclosure of Invention

Problems to be solved by the invention

However, in the rotating electrical machine described in patent document 2, since the flux barriers are all overlapped with the adjacent magnets in the circumferential direction, the magnetic path of the magnetic flux is narrowed. Therefore, the average torque may be greatly reduced.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a rotary electric machine capable of suppressing vibration while suppressing a decrease in average torque.

Means for solving the problems

In one embodiment of the rotating electrical machine of the present invention, the rotating electrical machine includes: a rotor rotatable about a central axis; and a stator located radially outward of the rotor, the rotor having: a rotor core having a plurality of receiving holes; and a plurality of magnets respectively accommodated in the plurality of accommodation holes, the stator having: a stator core having an annular core back surrounding the rotor core, and a plurality of teeth extending radially inward from the core back and arranged at intervals in a circumferential direction; and a plurality of coils mounted on the stator core, wherein the plurality of magnets include at least a pair of first magnets arranged at a distance from each other in a circumferential direction and extending in a direction that is separated from each other in the circumferential direction as seen in an axial direction from a radially inner side toward a radially outer side, the pair of first magnets constitute a pole, the plurality of coils are arranged in the circumferential direction with a q-axis interposed therebetween, the rotor core has a hole portion penetrating in the axial direction at a position of the q-axis in the circumferential direction as seen in the axial direction, and at least a part of the hole portion is located radially outer than the pair of first magnets.

Effects of the invention

According to one aspect of the present invention, in the rotating electrical machine, vibration can be suppressed while suppressing a decrease in average torque.

Drawings

Fig. 1 is a cross-sectional view showing a rotary electric machine according to the present embodiment.

Fig. 2 is a cross-sectional view showing a part of the rotating electrical machine according to the present embodiment, and is a cross-sectional view II-II in fig. 1.

Fig. 3 is a cross-sectional view showing a part of a magnetic pole portion and a stator core of the rotor according to the present embodiment.

Fig. 4 is an enlarged cross-sectional view of a part of a magnetic pole portion and a stator core of the rotor of the present embodiment.

Fig. 5 is a diagram showing the relationship between the respective increase/decrease ratios of the average torque, the torque ripple of the 6 th order component of the electric angle, and the torque ripple of the 12 th order component of the electric angle of the rotating electrical machine provided with the hole portion and the slot position with respect to the rotating electrical machine not provided with the hole portion.

Fig. 6 is a graph showing the relationship between the respective increase/decrease ratios of the average torque, the torque ripple of the 6 th order component of the electric angle, and the torque ripple of the 12 th order component of the electric angle of the rotating electrical machine provided with the hole portion and the slot length, with respect to the rotating electrical machine not provided with the hole portion.

Fig. 7 is a graph showing the average torque, torque ripple of 6 times component of electric angle, and increasing/decreasing ratio of torque ripple of 12 times component of electric angle of the rotating electrical machine provided with the hole portion with respect to the rotating electrical machine not provided with the hole portion.

Detailed Description

Hereinafter, a rotary electric machine 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 following drawings, the scale, the number, and the like of each structure may be different from the actual structure in order to facilitate understanding of each structure.

The Z-axis direction appropriately shown in each drawing is an up-down direction with the positive side as the "upper side" and the negative side as the "lower side". The central axis J shown in each figure is an imaginary line extending in the vertical direction in parallel with the Z-axis direction. In the following description, a direction parallel to the axial direction of the central axis J, that is, the up-down direction is simply referred to as an "axial direction", a radial direction centered on the central axis J is simply referred to as a "radial direction", and a circumferential direction centered on the central axis J is simply referred to as a "circumferential direction". The arrow θ appropriately shown in each figure indicates the circumferential direction. The arrow θ is directed clockwise around the center axis J as viewed from the upper side. In the following description, a side of the circumferential direction with reference to a certain object, which is directed to the arrow θ, i.e., a side that advances in the clockwise direction when viewed from the upper side, is referred to as "one circumferential side", and a side of the circumferential direction with reference to a certain object, which is opposite to the side directed to the arrow θ, i.e., a side that advances in the counterclockwise direction when viewed from the upper side, is referred to as "the other circumferential side".

The vertical direction, the upper side, and the lower side are only names for explaining the arrangement relation of the respective parts, and the actual arrangement relation may be an arrangement relation other than the arrangement relation represented by these names.

As shown in fig. 1, a rotary electric machine 1 of the present embodiment is an inner rotor type rotary electric machine.

In the present embodiment, the rotary electric machine 1 is a three-phase ac rotary electric machine. The rotary electric machine 1 is, for example, a three-phase motor driven by a power supply supplied with three-phase alternating current. The rotating electrical machine 1 includes a housing 2, a rotor 10, a stator 60, a bearing holder 4, and bearings 5a and 5b.

The housing 2 accommodates therein the rotor 10, the stator 60, the bearing holder 4, and the bearings 5a and 5b. The bottom of the housing 2 holds a bearing 5b. The bearing holder 4 holds a bearing 5a. The bearings 5a, 5b are, for example, ball bearings.

The stator 60 is located radially outward of the rotor 10. The stator 60 has a stator core 61, an insulator 64, and a plurality of coils 65. The stator core 61 has a core back 62 and a plurality of teeth 63. The core back 62 is located radially outward of the rotor core 20 described later. As shown in fig. 2, the core back 62 is annular surrounding the rotor core 20. The core back 62 is, for example, annular and centered on the center axis J.

A plurality of teeth 63 extend radially inward from the core back 62. The plurality of teeth 63 are arranged in a circumferentially spaced arrangement. The plurality of teeth 63 are arranged at regular intervals throughout the circumference, for example. The teeth 63 are provided with 48, for example. That is, the number of grooves 67 of the rotary electric machine 1 is, for example, 48. As shown in fig. 3 and 4, the plurality of teeth 63 have a base 63a and an umbrella 63b, respectively.

The base 63a extends radially inward from the core back 62. The circumferential dimension of the base 63a is, for example, the same throughout the radial direction. The circumferential dimension of the base 63a may be smaller as it goes radially inward, for example.

The umbrella 63b is provided at the radially inner end of the base 63 a. The umbrella 63b protrudes to both sides in the circumferential direction from the base 63 a. The circumferential dimension of the umbrella 63b is larger than the circumferential dimension of the radially inner end of the base 63 a. The radially inner surface of the umbrella 63b is a curved surface along the circumferential direction. The radially inner surface of the umbrella 63b extends in an arc shape centered on the central axis J, as viewed in the axial direction. The radially inner surface of the umbrella 63b faces the outer peripheral surface of the rotor core 20 described later with a gap therebetween in the radial direction. Among the teeth 63 adjacent to each other in the circumferential direction, the umbrella portions 63b are arranged in the circumferential direction with a gap therebetween.

A plurality of coils 65 are mounted to the stator core 61. As shown in fig. 1, a plurality of coils 65 are attached to the teeth 63 via, for example, insulators 64. In the present embodiment, the coils 65 are wound in a distributed manner. That is, each coil 65 is wound across the plurality of teeth 63. In the present embodiment, the coil 65 is wound at a full distance. That is, the circumferential pitch of the slots of the stator 60 into which the coils 65 are inserted is equal to the circumferential pitch of the magnetic poles generated when the three-phase ac power is supplied to the stator 60. The number of poles of the rotary electric machine 1 is eight, for example. That is, the rotary electric machine 1 is, for example, an 8-pole 48-slot rotary electric machine. As described above, in the rotating electrical machine 1 of the present embodiment, when the number of poles is N, the number of slots is n×6. In fig. 2 to 4, the insulator 64 is not shown.

The rotor 10 is rotatable about a central axis J. As shown in fig. 2, the rotor 10 has a shaft 11, a rotor core 20, and a plurality of magnets 40. The shaft 11 is cylindrical and extends in the axial direction about the central axis J. As shown in fig. 1, the shaft 11 is supported rotatably about the central axis J by bearings 5a and 5b.

The rotor core 20 is a magnetic body. The rotor core 20 is fixed to the outer peripheral surface of the shaft 11. The rotor core 20 has a through hole 21 penetrating the rotor core 20 in the axial direction. As shown in fig. 2, the through hole 21 is circular with the central axis J as the center, as viewed in the axial direction. The shaft 11 is passed through the through hole 21. The shaft 11 is fixed in the through hole 21 by press fitting or the like, for example. Although not shown, the rotor core 20 is configured by stacking a plurality of electromagnetic steel plates in the axial direction, for example.

The rotor core 20 has a plurality of receiving holes 30. The plurality of receiving holes 30 penetrate the rotor core 20 in the axial direction, for example. A plurality of magnets 40 are respectively accommodated in the plurality of accommodation holes 30. The method of fixing the magnet 40 in the receiving hole 30 is not particularly limited. The plurality of receiving holes 30 includes a pair of first receiving holes 31a, 31b and a second receiving hole 32.

The kind of the plurality of magnets 40 is not particularly limited. The magnet 40 may be, for example, a neodymium magnet or a ferrite magnet. The plurality of magnets 40 includes a pair of first magnets 41a, 41b and a second magnet 42. The pair of first magnets 41a, 41b and the second magnet 42 constitute a pole.

In the present embodiment, a plurality of the pair of first receiving holes 31a and 31b, the pair of first magnets 41a and 41b, the second receiving hole 32, and the second magnet 42 are provided at intervals in the circumferential direction. For example, eight pairs of first receiving holes 31a and 31b, a pair of first magnets 41a and 41b, a pair of second receiving holes 32, and a pair of second magnets 42 are provided.

The rotor 10 has a plurality of magnetic pole portions 70, and the magnetic pole portions 70 include one of each of the pair of first receiving holes 31a, 31b, the pair of first magnets 41a, 41b, the second receiving hole 32, and the second magnet 42. The magnetic pole portions 70 are provided with eight, for example. The plurality of magnetic pole portions 70 are arranged at regular intervals throughout the circumference, for example. The plurality of magnetic pole portions 70 includes a plurality of magnetic pole portions 70N having a magnetic pole of N pole on the outer peripheral surface of the rotor core 20 and a plurality of magnetic pole portions 70S having a magnetic pole of S pole on the outer peripheral surface of the rotor core 20. The magnetic pole portions 70N and 70S are provided with four, for example, each. The four magnetic pole portions 70N and the four magnetic pole portions 70S are alternately arranged in the circumferential direction. The structure of each magnetic pole portion 70 is similar except that the magnetic poles of the outer peripheral surface of the rotor core 20 are different and the circumferential positions are different.

As shown in fig. 3, in the magnetic pole portion 70, a pair of first receiving holes 31a, 31b are arranged at intervals in the circumferential direction. The first receiving hole 31a is located on one side (+θ side) in the circumferential direction of the first receiving hole 31b, for example. The first receiving holes 31a, 31b extend in a substantially straight line in a direction inclined with respect to the radial direction, for example, as viewed in the axial direction. The pair of first receiving holes 31a, 31b extend in a direction to be separated from each other in the circumferential direction as viewed in the axial direction from the radially inner side toward the radially outer side. That is, the distance in the circumferential direction between the first housing hole 31a and the first housing hole 31b increases from the radially inner side toward the radially outer side. The first receiving hole 31a is located on one side in the circumferential direction, for example, from the radially inner side toward the radially outer side. The first receiving hole 31b is located on the other side (- θ side) in the circumferential direction, for example, as going from the radially inner side toward the radially outer side. The radially outer end portions of the first receiving holes 31a, 31b are located at the radially outer peripheral edge portion of the rotor core 20.

The first receiving hole 31a and the first receiving hole 31b are arranged, for example, in the circumferential direction with a magnetic pole center line IL1 shown in fig. 3 constituting the d-axis therebetween, as viewed in the axial direction. The magnetic pole center line IL1 is an imaginary line extending in the radial direction through the circumferential center of the magnetic pole portion 70 and the center axis J. The first receiving hole 31a and the first receiving hole 31b are arranged, for example, line symmetrically with respect to the magnetic pole center line IL1 as viewed in the axial direction. Hereinafter, the first housing hole 31b may be omitted from the same structure as the first housing hole 31a except that it is line-symmetrical with respect to the magnetic pole center line IL 1.

The first receiving hole 31a has a first straight portion 31c, an inner end portion 31d, and an outer end portion 31e. The first linear portion 31c extends linearly in the direction in which the first receiving hole 31a extends, as viewed in the axial direction. The first straight portion 31c is rectangular, for example, when viewed in the axial direction. The inner end 31d is connected to a radially inner end of the first straight portion 31 c. The inner end 31d is an end of the first receiving hole 31a radially inward. The outer end 31e is connected to a radially outer end of the first straight portion 31 c. The outer end 31e is an end of the first receiving hole 31a radially outward. The first receiving hole 31b has a first straight portion 31f, an inner end portion 31g, and an outer end portion 31h.

The second receiving hole 32 is located between the end portions of the pair of first receiving holes 31a, 31b on the outer side in the radial direction in the circumferential direction. That is, in the present embodiment, the second receiving hole 32 is located between the outer end 31e and the outer end 31h in the circumferential direction. The second receiving hole 32 extends in a substantially straight line in a direction orthogonal to the radial direction, for example, as viewed in the axial direction. The second receiving hole 32 extends, for example, in a direction orthogonal to the magnetic pole center line IL1 as viewed in the axial direction. The pair of first receiving holes 31a, 31b and the second receiving hole 32 are arranged in a # -shape, for example, as viewed in the axial direction.

In the present specification, the term "a certain object extends in a direction orthogonal to a certain direction" includes a case where a certain object extends in a direction substantially orthogonal to a certain direction, as well as a case where a certain object extends in a direction strictly orthogonal to a certain direction. The "direction substantially orthogonal to the certain direction" includes, for example, a direction inclined within a range of about several degrees [ ° ] with respect to a direction strictly orthogonal to the certain direction due to a tolerance or the like at the time of manufacture.

The magnetic pole center line IL1 passes through the center of the second housing hole 32 in the circumferential direction, for example, as viewed in the axial direction. That is, the circumferential position of the circumferential center of the second accommodation hole 32 coincides with the circumferential position of the circumferential center of the magnetic pole portion 70, for example. The shape of the second receiving hole 32 viewed in the axial direction is, for example, a line-symmetrical shape centered on the magnetic pole center line IL 1. The second receiving hole 32 is located at the radially outer peripheral edge portion of the rotor core 20.

The second receiving hole 32 has a second straight portion 32a, one end portion 32b, and the other end portion 32c. The second linear portion 32a extends in a linear shape along the direction in which the second accommodation hole 32 extends, as viewed in the axial direction. The second straight portion 32a is rectangular, for example, when viewed in the axial direction. One end 32b is connected to one end of the second linear portion 32a on one side (+θ side) in the circumferential direction. The one end 32b is one end of the second accommodation hole 32 on the circumferential direction side. One end 32b is disposed at a distance from the other side (- θ side) in the circumferential direction of the outer end 31e of the first housing hole 31 a. The other end portion 32c is connected to the other end portion (- θ side) of the second linear portion 32a in the circumferential direction. The other end 32c is the end on the other side in the circumferential direction of the second accommodation hole 32. The other end portion 32c is disposed at a distance from one side in the circumferential direction of the outer end portion 31h of the first housing hole 31 b.

The pair of first magnets 41a, 41b are respectively accommodated in the pair of first accommodation holes 31a, 31 b. The first magnet 41a is accommodated in the first accommodation hole 31 a. The first magnet 41b is accommodated in the first accommodation hole 31 b. The pair of first magnets 41a, 41b is rectangular, for example, when viewed in the axial direction. The lengths of the pair of first magnets 41a, 41b in the extending direction are the same. The lengths of the first magnets 41a, 41b in the direction orthogonal to the direction in which the pair of first magnets 41a, 41b extends are the same.

Although not shown, the first magnets 41a and 41b have a rectangular parallelepiped shape, for example. Although not shown, the first magnets 41a and 41b are provided throughout the entire axial direction in the first housing holes 31a and 31b, for example. The pair of first magnets 41a, 41b are arranged at a distance from each other in the circumferential direction. The first magnet 41a is located on one side (+θ side) in the circumferential direction of the first magnet 41b, for example.

The first magnet 41a extends along the first receiving hole 31a as viewed in the axial direction. The first magnet 41b extends along the first receiving hole 31b as viewed in the axial direction. The first magnets 41a, 41b extend in a substantially straight line in a direction inclined with respect to the radial direction, for example, as viewed in the axial direction. The pair of first magnets 41a, 41b extend in a direction to be separated from each other in the circumferential direction as viewed in the axial direction from the radially inner side toward the radially outer side. That is, the circumferential distance between the first magnet 41a and the first magnet 41b increases from the radially inner side toward the radially outer side.

The first magnet 41a is located on one side (+θ side) in the circumferential direction, for example, as going from the radially inner side to the radially outer side. The first magnet 41b is located on the other side (- θ side) in the circumferential direction, for example, from the radially inner side toward the radially outer side. The first magnet 41a and the first magnet 41b are disposed, for example, in the circumferential direction with the magnetic pole center line IL1 therebetween, as viewed in the axial direction. The first magnet 41a and the first magnet 41b are arranged, for example, line symmetrically with respect to the magnetic pole center line IL1 as viewed in the axial direction. Hereinafter, the same structure as the first magnet 41a except for the line symmetry with respect to the magnetic pole center line IL1 may be omitted from the description of the first magnet 41 b.

The first magnet 41a is fitted into the first receiving hole 31 a. More specifically, the first magnet 41a is fitted into the first linear portion 31 c. Of the side surfaces of the first magnet 41a, the side surfaces in the direction orthogonal to the direction in which the first straight line portion 31c extends are in contact with the inner side surfaces of the first straight line portion 31c, for example. The length of the first magnet 41a is, for example, the same as the length of the first straight line portion 31c in the direction in which the first straight line portion 31c extends, as viewed in the axial direction.

The both end portions of the first magnet 41a in the extending direction are arranged so as to be separated from the both end portions of the first receiving hole 31a in the extending direction, respectively, as viewed in the axial direction. The inner end 31d and the outer end 31e are disposed adjacent to each other on both sides of the first magnet 41a in the direction in which the first magnet 41a extends, as viewed in the axial direction. Here, in the present embodiment, the inner end portion 31d constitutes the first magnetic flux shielding portion 51a. The outer end 31e constitutes a first magnetic flux shielding portion 51b. That is, the rotor core 20 has a pair of first magnetic flux shielding portions 51a, 51b arranged across the first magnet 41a in the direction in which the first magnet 41a extends, as viewed in the axial direction. The rotor core 20 has a pair of first magnetic flux shielding portions 51c, 51d arranged across the first magnet 41b in the direction in which the first magnet 41b extends, as viewed in the axial direction.

As described above, the rotor core 20 has a pair of first magnetic flux shielding portions 51a, 51b, 51c, 51d arranged across each of the first magnets 41a, 41b in the direction in which the first magnets 41a, 41b extend, as viewed in the axial direction. The first magnetic flux shielding portions 51a, 51b, 51c, and 51d, the second magnetic flux shielding portions 52a and 52b described later, and the hole portion 80 described later are portions capable of suppressing the flow of magnetic flux. That is, it is difficult for the magnetic flux to pass through each of the magnetic flux shielding portions and the groove portions. The magnetic flux shielding portions and the groove portions are not particularly limited as long as the flow of the magnetic flux can be suppressed, and may include a void portion or a nonmagnetic portion such as a resin portion.

The second magnet 42 is accommodated in the second accommodation hole 32. The second magnet 42 is disposed radially outward of the radially inner ends of the pair of first magnets 41a, 41b at a circumferential position between the pair of first magnets 41a, 41 b. The second magnet 42 extends along the second receiving hole 32 as viewed in the axial direction. The second magnet 42 extends in a direction orthogonal to the radial direction as viewed in the axial direction. The pair of first magnets 41a, 41b and the second magnet 42 are arranged in a # -shape, for example, as viewed in the axial direction.

In the present specification, the phrase "the circumferential position of the second magnet disposed between the pair of first magnets" means that the circumferential position of the second magnet is not particularly limited as long as the circumferential position is included in the circumferential position between the pair of first magnets, and the radial position of the second magnet with respect to the first magnets.

The shape of the second magnet 42 viewed in the axial direction is, for example, a shape line-symmetrical with respect to the magnetic pole center line IL 1. The second magnet 42 is, for example, rectangular in axial view. Although not shown, the second magnet 42 is, for example, rectangular parallelepiped. Although not shown, the second magnet 42 is provided throughout the entire axial direction in the second housing hole 32, for example. The radially inner portion of the second magnet 42 is located, for example, between the circumferential directions of the radially outer end portions of the pair of first magnets 41a, 41 b. The radially outer portion of the second magnet 42 is located radially outward of the pair of first magnets 41a, 41b, for example.

The second magnet 42 is fitted into the second receiving hole 32. More specifically, the second magnet 42 is fitted into the second linear portion 32 a. Of the side surfaces of the second magnet 42, two side surfaces in the radial direction orthogonal to the direction in which the second straight line portion 32a extends are in contact with, for example, the inner side surfaces of the second straight line portion 32a, respectively. The length of the second magnet 42 is, for example, the same as the length of the second straight portion 32a in the direction in which the second straight portion 32a extends, as viewed in the axial direction.

The two ends of the second magnet 42 in the extending direction are disposed separately from the two ends of the second housing hole 32 in the extending direction, respectively, as viewed in the axial direction. One end portion 32b and the other end portion 32c are disposed adjacent to each other on both sides of the second magnet 42 in the direction in which the second magnet 42 extends, as viewed in the axial direction. Here, in the present embodiment, the one end portion 32b constitutes the second magnetic flux shielding portion 52a. The other end portion 32c constitutes a second magnetic flux shielding portion 52b. That is, the rotor core 20 has a pair of second magnetic flux shielding portions 52a, 52b arranged across the second magnet 42 in the direction in which the second magnet 42 extends, as viewed in the axial direction. The pair of second magnetic flux shielding portions 52a and 52b and the second magnet 42 are located between the radially outer first magnetic flux shielding portion 51b of the pair of first magnetic flux shielding portions 51a and 51b sandwiching the first magnet 41a and the circumferential direction of the radially outer first magnetic flux shielding portion 51d of the pair of first magnetic flux shielding portions 51c and 51d sandwiching the first magnet 41 b.

The magnetic poles of the first magnet 41a are arranged in a direction orthogonal to the direction in which the first magnet 41a extends, as viewed in the axial direction. The magnetic poles of the first magnet 41b are arranged in a direction orthogonal to the direction in which the first magnet 41b extends, as viewed in the axial direction. The poles of the second magnet 42 are arranged in the radial direction.

The magnetic pole located radially outward of the magnetic poles of the first magnet 41a, the magnetic pole located radially outward of the magnetic poles of the first magnet 41b, and the magnetic pole located radially outward of the magnetic poles of the second magnet 42 are identical to each other. The radially inner one of the magnetic poles of the first magnet 41a, the radially inner one of the magnetic poles of the first magnet 41b, and the radially inner one of the magnetic poles of the second magnet 42 are identical to each other.

As shown in fig. 3, in the magnetic pole portion 70N, a magnetic pole located radially outward of the magnetic poles of the first magnet 41a, a magnetic pole located radially outward of the magnetic poles of the first magnet 41b, and a magnetic pole located radially outward of the magnetic poles of the second magnet 42 are, for example, N poles. In the magnetic pole portion 70N, a magnetic pole located radially inward of the magnetic poles of the first magnet 41a, a magnetic pole located radially inward of the magnetic poles of the first magnet 41b, and a magnetic pole located radially inward of the magnetic poles of the second magnet 42 are, for example, S-poles.

Although not shown, the magnetic poles of the magnets 40 are arranged in the magnetic pole portion 70S in a reverse direction with respect to the magnetic pole portion 70N. That is, in the magnetic pole portion 70S, the magnetic pole located radially outward of the magnetic poles of the first magnet 41a, the magnetic pole located radially outward of the magnetic poles of the first magnet 41b, and the magnetic pole located radially outward of the magnetic poles of the second magnet 42 are, for example, S-poles. In the magnetic pole portion 70S, a magnetic pole located radially inward of the magnetic poles of the first magnet 41a, a magnetic pole located radially inward of the magnetic poles of the first magnet 41b, and a magnetic pole located radially inward of the magnetic poles of the second magnet 42 are, for example, N poles.

In a certain state (hereinafter, simply referred to as a certain state) in which the circumferential center of the second magnet 42 and the circumferential center of any one of the teeth 63 are arranged at the same circumferential position, the teeth 63 having the circumferential center arranged at the same circumferential position as the circumferential center of the second magnet 42 are referred to as teeth 66A. Fig. 2 to 3 show an example of this certain state. That is, in a certain state shown in fig. 2 to 3, the tooth 66A corresponds to "a certain tooth". In a certain state shown in fig. 2 to 3, the magnetic pole center line IL1 passes through the circumferential center of the tooth 66A as viewed in the axial direction. In the present specification, the "certain state" is a state in which the circumferential center position of the tooth 66A coincides with the magnetic pole center line IL1 as the d-axis.

In a certain state shown in fig. 2 to 3, the tooth 63 adjacent to one side (+θ side) in the circumferential direction of the tooth 66A is referred to as a tooth 66B. The tooth 63 adjacent to the other side (- θ side) in the circumferential direction of the tooth 66A is referred to as a tooth 66C. The tooth 63 adjacent to one side in the circumferential direction of the tooth 66B is referred to as a tooth 66D. The tooth 63 adjacent to the other circumferential side of the tooth 66C is referred to as a tooth 66E. The tooth 63 adjacent to one side in the circumferential direction of the tooth 66D is referred to as a tooth 66F. The tooth 63 adjacent to the other circumferential side of the tooth 66E is referred to as a tooth 66G.

As shown in fig. 3, the rotor core 20 has a hole portion 80. The hole 80 penetrates the rotor core 20 in the axial direction. The q-axis IL2 passes through the circumferential center of the hole portion 80 as viewed in the axial direction. The q-axis IL2 is an axis extending in a direction electrically perpendicular to the d-axis. The hole 80 is disposed on each of the q-axes IL 2. The hole 80 is disposed at a position radially inward of the outer peripheral surface of the rotor core 20 by a distance L1 when viewed in the axial direction.

The hole 80 is an elongated groove extending in the radial direction and having a maximum radial length L2 greater than the circumferential length. The hole 80 functions as a third magnetic flux shielding portion. The hole 80 has a semicircular shape having a center on the q-axis IL2 at both ends in the radial direction. Since both ends of the hole 80 in the radial direction are semicircular, stress concentration at the hole 80 can be relaxed. The dimension in the circumferential direction of the hole 80 on the inner side of the semicircle is constant.

As shown in fig. 4, the hole 80 is arranged at intervals in the circumferential direction from the first magnetic flux shielding portions 51b and 51d adjacent to each other in the circumferential direction with the q-axis IL2 interposed therebetween. The hole 80 is disposed at a circumferentially spaced apart interval from the first magnets 41a and 41b adjacent to each other in the circumferential direction with the q-axis IL2 interposed therebetween. The shortest distance between the q-axis IL2 and the first magnets 41a, 41b is shorter than the shortest distance between the q-axis IL2 and the first magnetic flux shielding portions 51b, 51d.

For example, when the magnetic flux flowing through the rotor core 20 includes the magnetic flux B12 of the electric angle 12 sub-component shown in fig. 4, the magnetic flux B12 from the stator core 61 flows radially inward. The magnetic flux B12 bypasses the hole 80 and is branched into a path flowing between the first magnetic flux shielding portion 51B and the hole 80 and a path flowing between the first magnetic flux shielding portion 51d and the hole 80. The magnetic flux B12 is branched into two magnetic paths, whereby the magnetic flux B12 can be appropriately rectified. This can reduce the flow unevenness of the magnetic flux more appropriately in the circumferential direction, and can reduce the torque ripple more appropriately. Since the magnetic flux B12 of the electric angle 6 th order component flowing from the first magnets 41a, 41B is eliminated, the torque ripple of the electric angle 12 th order component can be further reduced.

Fig. 5 is a diagram showing the relationship between the average torque, torque ripple of 6-degree electric angle components, and torque ripple of 12-degree electric angle components of the rotating electrical machine 1 provided with the hole 80 and the average torque, the average torque ripple of 12-degree electric angle components of the rotating electrical machine 1 provided with the hole 80, and the slot position, when the distance L1 is set to the slot position and the maximum length L2 is set to 2 mm.

As shown in fig. 5, with respect to the slot positions, by separating the hole portions 80 radially inward from the outer peripheral surface of the rotor core 20, the increase ratio of the torque ripple of the 6-order component of the electric angle is temporarily increased. By increasing the distance L1 of the hole 80 from the rotor core 20, the increase ratio of torque ripple of the 6-order component of the electric angle can be suppressed. By separating the hole 80 from the outer peripheral surface of the rotor core 20 to the radially inner side, the increase ratio of the torque ripple of the 12-order component of the electric angle is reduced. The increase ratio of the average torque is constant irrespective of the distance L1 of the hole 80 from the rotor core 20.

Fig. 6 is a graph showing the relationship between the average torque, torque ripple of 6-degree electric angle components, and torque ripple of 12-degree electric angle components of the rotating electrical machine 1 provided with the hole 80 and the average torque, the average torque ripple of 12-degree electric angle components of the rotating electrical machine 1 provided with the hole 80, and the slot length, when the maximum length L2 is the slot length and the distance L1 is 2 mm.

As shown in fig. 6, the ratio of increase in torque ripple of the 6-order component of the electric angle does not change significantly with respect to the change in the maximum length L2 with respect to the slot length. By increasing the maximum length L2, the increase ratio of the torque ripple of the 12-degree component of the electric angle is reduced. The increase ratio of the average torque is constant irrespective of the maximum length L2.

Fig. 7 is a diagram showing the respective increasing/decreasing ratios of the average torque, the torque ripple of the 6 th order component of the electric angle, and the torque ripple of the 12 th order component of the electric angle of the rotating electric machine 1 provided with the hole 80 with respect to the rotating electric machine 1 not provided with the hole 80, when the circumferential width of the hole 80 is set to 2mm, the distance L1 is set to 2mm, and the maximum length L2 is set to 2 mm.

As shown in fig. 7, in the rotary electric machine 1 having the hole 80 having the above-described dimensions, a large change was not found in both the average torque and the torque ripple of the 6-order component of the electric angle with respect to the rotary electric machine 1 not provided with the hole 80. The torque ripple of the 12-order component of the electric angle can be reduced by providing the hole 80. According to the present embodiment, by providing the hole 80, torque pulsation due to the magnetic flux component of the electric angle 12 times can be suppressed without reducing the average torque, and vibration and noise can be reduced.

At least a part of the hole 80 is located radially outward of the pair of first magnets 41a, 41 b. In the case where the hole portion 80 is entirely overlapped with the pair of first magnets 41a, 41b in the circumferential direction, the space between the hole portion 80 and the first magnets 41a, 41b is narrowed. This impedes the flow of the magnetic flux B12, and the average torque may be significantly reduced. The shortest distance between the hole 80 located radially outward of the pair of first magnets 41a, 41b and the pair of first magnetic flux shielding portions 51b, 51d in the circumferential direction is longer than the shortest distance between the hole 80 and the pair of first magnets 41a, 41b in the circumferential direction.

Therefore, by positioning at least a part of the hole 80 radially outward of the pair of first magnets 41a, 41B, the magnetic flux B12 can flow in a region where the shortest distance between the hole 80 radially outward of the pair of first magnets 41a, 41B and the circumferential direction of the pair of first magnets 41a, 41B is longer. According to the present embodiment, by flowing the magnetic flux B12 in the region where the shortest distance in the circumferential direction is long, it is possible to suppress a decrease in average torque.

The radial position of the hole 80 in the present embodiment is located radially outward of the position where the distance between the adjacent first magnets 41a, 41b in the circumferential direction is shortest, with the q-axis IL2 interposed therebetween. According to the present embodiment, the magnetic flux B12 can flow in a region having a long circumferential distance by positioning the radial position of the hole 80 radially outside the position having the shortest circumferential distance between the first magnets 41a and 41B, and thus the reduction of the average torque can be suppressed.

The radial position of the hole 80 of the present embodiment is in a range between the radially outermost position and the radially innermost position of the first magnetic flux shielding portions 51b and 51d adjacent to each other with the q-axis IL2 interposed therebetween. According to the present embodiment, by setting the radial position of the hole 80 to be within the range between the radially outermost position and the radially innermost position of the first magnetic flux shielding portions 51B and 51d, the magnetic flux B12 can flow between the hole 80 and the first magnetic flux shielding portions 51B and 51d, which are longer in the circumferential direction than between the hole 80 and the first magnets 41a and 41B, and the reduction in average torque can be suppressed.

The preferred embodiments of the present invention have been described above with reference to the drawings, but the present invention is not limited to the above examples. The shapes, combinations, and the like of the respective constituent members shown in the above examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, the structure in which the radial position of the hole 80 is in the range between the radially outermost position and the radially innermost position of the first magnetic flux shielding portions 51b, 51d adjacent to each other with the q-axis IL2 interposed therebetween has been illustrated, but the structure is not limited thereto. The radial position of the hole 80 may be another radial position as long as at least a part of the hole 80 is located radially outward of the pair of first magnets 41a, 41 b.

For example, in the above embodiment, the v-shaped magnet 40 having the first magnets 41a, 41b and the second magnet 42 is exemplified, but the configuration is not limited thereto. For example, the magnet 40 may be a rotary electric machine 1 having a structure in which the second magnet 42 is not provided, and the pole piece is adjacent to the first magnets 41a and 41b arranged in a V-shape. For example, the magnet 40 may be a rotary electric machine 1 having a structure in which a plurality of groups (for example, two groups) of pole pieces are arranged adjacent to the first magnets 41a and 41b at intervals in the radial direction without the second magnet 42.

The rotary electric machine to which the present invention is applied is not limited to the motor, but may be a generator. In this case, the rotating electrical machine may be a three-phase ac type generator. The use of the rotary electric machine is not particularly limited. The rotating electric machine may be mounted on a vehicle, for example, or may be mounted on a device other than the vehicle. The number of poles and slots of the rotating electrical machine is not particularly limited. In the rotating electric machine, the coil may be formed by any winding method. The structures described above in this specification can be appropriately combined within a range not contradicting each other.

Symbol description

1-rotating electrical machine, 10-rotor, 20-rotor core, 30-housing hole, 40-magnet, 41a, 41B-first magnet, 42-second magnet, 51a, 51B, 51C, 51D-first magnetic flux shielding portion (magnetic flux shielding portion), 52a, 52B-second magnetic flux shielding portion, 53a, 53B, 54a, 54B-slot portion, 60-stator, 61-stator core, 62-core back portion, 63, 66A, 66B, 66C, 66D, 66E-tooth, 65-coil, 67-slot, 70N, 70S-magnetic pole portion, 80A, 80B-hole portion, IL 1-magnetic pole center line (D axis), IL 2-q axis, J-center axis.

Claims

1. A rotary electric machine is characterized in that,

the device is provided with:

a rotor rotatable about a central axis; and

a stator located radially outward of the rotor,

the rotor has:

a rotor core having a plurality of receiving holes; and

a plurality of magnets respectively accommodated in the plurality of accommodation holes,

the stator has:

a stator core having an annular core back surrounding the rotor core, and a plurality of teeth extending radially inward from the core back and arranged at intervals in a circumferential direction; and

a plurality of coils mounted to the stator core,

the plurality of magnets includes at least a pair of first magnets arranged at intervals in the circumferential direction and extending in a direction to be separated from each other in the circumferential direction as seen in the axial direction from the radially inner side toward the radially outer side,

the pair of first magnets constitute a pole, and a plurality of magnets are arranged in the circumferential direction with a q-axis interposed therebetween,

the rotor core has a hole portion penetrating in the axial direction at the q-axis position in the circumferential direction as viewed in the axial direction,

at least a part of the hole portion is located radially outward of the pair of first magnets.

2. The rotating electrical machine according to claim 1, wherein,

the hole portion extends in a radial direction, and a radial length is larger than a circumferential length.

3. The rotating electrical machine according to claim 2, wherein,

the radial two ends of the hole part are arc-shaped when seen along the axial direction.

4. A rotary electric machine according to any one of claim 1 to 3, wherein,

the rotor core has a magnetic flux shielding portion,

a pair of the magnetic flux shielding portions are arranged in the direction in which the first magnets extend, with each of the first magnets interposed therebetween, as viewed in the axial direction,

the radial position of the hole is in a range between a radially outermost position and a radially innermost position of a radially outer magnetic flux shielding portion of the pair of magnetic flux shielding portions.

5. The rotating electrical machine according to any one of claims 1 to 4, wherein,

the hole is located radially outward of a position where a distance between adjacent first magnets in a circumferential direction across the q-axis is shortest.

6. The rotating electrical machine according to any one of claims 1 to 5, wherein,

the magnetic head includes a second magnet disposed at a circumferential position between the pair of first magnets radially outward of radially inner ends of the pair of first magnets, and extending in a direction orthogonal to a radial direction when viewed in an axial direction.