CN116888861A - Rotary electric machine - Google Patents

Abstract

The invention provides a rotating electrical machine. One embodiment of the rotating electrical machine 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 which are respectively accommodated in the plurality of accommodating holes. The stator has: a stator core having an annular core back surrounding the rotor core and a plurality of teeth extending from the core back to the radial inner side and arranged at intervals in the circumferential direction; and a plurality of coils mounted to the stator core. The plurality of magnets are arranged in the circumferential direction with the q-axis interposed therebetween, and the rotor core has a pair of grooves recessed inward in the radial direction on both sides of the q-axis in the circumferential direction of the outer circumferential surface at intervals when viewed in the axial direction. When the maximum dimension in the radial direction of the groove portion is L1 and the minimum dimension in the circumferential direction of the pair of groove portions is L2, the relationship of 0.8.ltoreq.L 2/L1.ltoreq.1.2 is satisfied.

Description

Rotary electric machine

Technical Field

The present invention relates to a rotating electrical machine.

Background

A rotating electrical machine such as an embedded magnet type synchronous motor (IPMSM) is known that includes a rotor core and permanent magnets disposed in holes provided in the rotor core. In such a rotary electric machine, as measures against demagnetization, grooves, protrusions, slits, holes, and the like are provided in the rotor core, and measures against the size and material of the magnet itself, the temperature change of the magnet, and the like are adopted. For example, patent document 1 discloses a rotary electric machine in which permanent magnets are arranged in a V shape, and two sets of magnet portions constituting the V shape are arranged so that the magnetization directions of the magnet portions are oriented in a first magnet portion and a second magnet portion, respectively, intersecting each other, thereby suppressing demagnetization of the magnet.

In a 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 where the contribution degree of the electromagnetic exciting force acting between the rotor and the stator of the exciting motor is high, for example, patent document 2 discloses that a groove recessed inward in the radial direction is provided on the outer peripheral surface of the rotor core. In the rotating electrical machine described in patent document 2, by providing the grooves on the outer peripheral surface of the rotor core, the air gap with the stator becomes large, and thus the electromagnetic excitation force in the circumferential direction can be reduced.

Prior art literature

Patent literature

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

Patent document 2: japanese patent laid-open No. 2009-213256

Disclosure of Invention

Problems to be solved by the invention

In the rotating electrical machine described above, depending on the application of the motor, the drive range may be wide, and the higher the rotation speed of the motor, the more d-axis (direct axis) current may flow to reduce the induced voltage. In this case, the balance between the d-axis magnetic flux and the q-axis (quadrature axis) magnetic flux in the motor also varies greatly, and the electromagnetic excitation force for exciting the motor also varies greatly. For example, the motor has a circumferential electromagnetic excitation force as a noise source at a low speed, and a radial electromagnetic excitation force as a noise source at a high speed. Therefore, it is necessary to use 1 motor shape to cope with electromagnetic excitation forces of different components in the circumferential direction and the radial direction, but it cannot be said that the slot described in patent document 2 sufficiently considers electromagnetic excitation forces at low speed and at high speed.

The present invention has been made in view of the above-described problems, and an object thereof is to provide a rotary electric machine capable of reducing noise independently of the rotation speed of the motor.

Means for solving the problems

One embodiment of the rotating electrical machine of the present invention 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, wherein the stator includes: 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 circumferentially spaced intervals; and a plurality of coils mounted on the stator core, the plurality of magnets forming poles and being arranged in the circumferential direction with a q-axis interposed therebetween, wherein the rotor core has a pair of groove portions recessed inward in the radial direction on both sides of the q-axis in the circumferential direction at intervals when viewed in the axial direction, and the rotor core satisfies a relationship of 0.8 (L2/L1) or less when a maximum dimension in the radial direction of the groove portions is L1 and a minimum dimension in the circumferential direction of the pair of groove portions is L2.

ADVANTAGEOUS EFFECTS OF INVENTION

According to one aspect of the present invention, noise can be reduced in a rotating electrical machine independently of the rotational speed of an electric motor.

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 the periphery of the groove portion radially opposed to the tooth 66F.

Fig. 5 is a graph showing a relationship between the rotation speed of the motor and the increasing/decreasing ratio of the 12-time radial electromagnetic excitation force.

Fig. 6 is a graph showing a relationship between the rotation speed of the motor and the increasing/decreasing ratio of 12 times of the circumferential electromagnetic excitation force.

Fig. 7 is a graph showing a relationship between the number of grooves and the increasing/decreasing ratio of the average torque, and showing a relationship between the number of grooves and the increasing/decreasing ratio of the electromagnetic excitation force 12 times at the electrical angle.

Fig. 8 is an enlarged cross-sectional view of the periphery of a slot portion of a rotating electrical machine having "1 slot".

Fig. 9 is a diagram showing a relationship between a groove width L3 and each of an average torque, an electric angle 12 times radial electromagnetic excitation force, and an electric angle 12 times circumferential electromagnetic excitation force in a rotary electric machine having a groove 80C with respect to a rotary electric machine not provided with a groove.

Fig. 10 is a graph showing a relationship between the groove width L3 and each of the average torque, the electric angle 12 times of the radial electromagnetic excitation force, and the electric angle 12 times of the increase/decrease ratio of the circumferential electromagnetic excitation force.

Fig. 11 is a graph showing a relationship between a minimum dimension L2 of a circumferential interval between grooves and each of an average torque, an electric angle 12 times of radial electromagnetic excitation force, and an electric angle 12 times of increasing/decreasing ratio of the circumferential electromagnetic excitation force.

In the figure: a 1 … rotary electric machine; 10 … rotor; 20 … rotor core; 20a … outer circumferential surfaces; 30 … receiving holes; 40 … magnets; 41a, 41b … first magnets; 42 … second magnet; 51b, 51d … first magnetic flux barriers (magnetic flux barriers); 52a, 52b … second magnetic flux barriers; a 60 … stator; 61 … stator core; 62 … core back; 63. 66A, 66B, 66C, 66D, 66E … teeth; 65 … coil; 67 … slots; 70. 70N, 70S … pole portions; 80A, 80B … groove portions; 81. 82 … first straight portions; 83 … second straight line portion; 84. 85 … curve; IL1 … pole centerline (d axis); IL2 … q axis; j … central axis.

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 drawings below, the scale, the number, and the like of each structure may be different from those of the actual structure in order to facilitate understanding of each structure.

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

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, core back 62 is annular surrounding rotor core 20. The core back 62 is, for example, annular with the center axis J as the center.

A plurality of teeth 63 extend radially inward from the core back 62. The plurality of teeth 63 are arranged at circumferentially spaced intervals. The plurality of teeth 63 are arranged at equal intervals throughout the circumference, for example, along the circumferential direction. The teeth 63 are provided with 48, for example. That is, the number of slots 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 the same throughout the radial direction, for example. 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 when viewed in the axial direction. The radially inner surface of the umbrella 63b faces the outer circumferential surface of the rotor core 20 described later with a gap therebetween in the radial direction. In the circumferentially adjacent teeth 63, the umbrella portions 63b are arranged in a circumferential direction with a gap therebetween.

A plurality of coils 65 are mounted on the stator core 61. As shown in fig. 1, a plurality of coils 65 are mounted on 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 so as to span the plurality of teeth 63. In the present embodiment, the coil 65 is wound in full sections. 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 alternating current power is supplied to the stator 60. The number of poles of the rotating electrical machine 1 is 8, 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 3, 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 when viewed in the axial direction. The shaft 11 passes 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 for fixing the magnet 40 in the housing 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 type 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 accommodation holes 31a and 31b, the pair of first magnets 41a and 41b, the second accommodation hole 32, and the second magnet 42 are provided at intervals in the circumferential direction. For example, 8 pairs of first accommodation holes 31a and 31b, a pair of first magnets 41a and 41b, a pair of second accommodation holes 32, and a pair of second magnets 42 are provided.

The rotor 10 has a plurality of magnetic pole portions 70, and each magnetic pole portion 70 includes a pair of first receiving holes 31a, 31b, a pair of first magnets 41a, 41b, a second receiving hole 32, and a second magnet 42. The number of the magnetic pole portions 70 is 8, for example. The plurality of magnetic pole portions 70 are arranged at equal intervals throughout the circumference, for example, along the circumferential direction. The plurality of magnetic pole portions 70 include a magnetic pole portion 70N of the N pole of the outer circumferential surface of the plurality of rotor cores 20 and a magnetic pole portion 70S of the S pole of the outer circumferential surface of the rotor cores 20. For example, 4 magnetic pole portions 70N and 4 magnetic pole portions 70S are provided. The 4 magnetic pole portions 70N and the 4 magnetic pole portions 70S are alternately arranged in the circumferential direction. The structure of each magnetic pole portion 70 is the same except that the magnetic poles of the outer circumferential 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 accommodation hole 31a is located on one side (+θ side) in the circumferential direction of the first accommodation hole 31b, for example. The first accommodation holes 31a and 31b extend substantially linearly in a direction inclined with respect to the radial direction, for example, when viewed in the axial direction. The pair of first receiving holes 31a, 31b extend in a direction away from each other in the circumferential direction as seen 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 accommodation hole 31a and the first accommodation hole 31b increases from the radially inner side toward the radially outer side. The first accommodation 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 accommodation 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 and 31b are located at the radially outer peripheral edge portion of the rotor core 20.

The first accommodation hole 31a and the first accommodation hole 31b are arranged, for example, so as to sandwich a magnetic pole center line IL1 shown in fig. 3 constituting the d-axis in the circumferential direction when viewed in the axial direction. The magnetic pole center line IL1 is an imaginary line passing through the circumferential center of the magnetic pole portion 70 and the center axis J and extending in the radial direction. The first accommodation hole 31a and the first accommodation hole 31b are arranged, for example, line-symmetrically with respect to the magnetic pole center line IL1 when 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 for the point of line symmetry 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 accommodation hole 31a extends, as viewed in the axial direction. The first straight portion 31c has a rectangular shape when viewed in the axial direction, for example. 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 housing 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 housing hole 31a radially outside. The first receiving hole 31b has a first straight portion 31f, an inner end portion 31g, and an outer end portion 31h.

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

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 strictly orthogonal to a certain direction and a case where a certain object extends in a direction substantially orthogonal to a certain direction. The "direction substantially orthogonal to the certain direction" includes a direction inclined within a range of about several degrees (°) with respect to a direction strictly orthogonal to the certain direction due to, for example, a tolerance at the time of manufacturing.

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

The second accommodation hole 32 has a second straight portion 32a, one end portion 32b, and the other end portion 32c. The second linear portion 32a extends linearly in the direction in which the second accommodation hole 32 extends, as viewed in the axial direction. The second straight portion 32a has a rectangular shape when viewed in the axial direction, for example. 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. The one end portion 32b is disposed at a distance from the other side (- θ side) in the circumferential direction of the outer end portion 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 and 41b are accommodated in the pair of first accommodation holes 31a and 31b, respectively. 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 has a rectangular shape when viewed in the axial direction, for example. The lengths of the pair of first magnets 41a and 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 extend are the same.

Although not shown, the first magnets 41a and 41b are, for example, rectangular parallelepiped. Although not shown, the first magnets 41a and 41b are provided in 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 accommodation hole 31a when viewed in the axial direction. The first magnet 41b extends along the first accommodation hole 31b when viewed in the axial direction. The first magnets 41a, 41b extend substantially linearly in a direction inclined with respect to the radial direction, for example, when viewed in the axial direction. The pair of first magnets 41a, 41b extend in a direction away from each other in the circumferential direction as seen 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, from the radially inner side toward 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, so as to sandwich the magnetic pole center line IL1 in the circumferential direction when viewed in the axial direction. The first magnet 41a and the first magnet 41b are arranged, for example, so as to be line-symmetrical with respect to the magnetic pole center line IL1 when viewed in the axial direction. Hereinafter, the first magnet 41b may be omitted from the same configuration as the first magnet 41a except for the point of line symmetry with respect to the magnetic pole center line IL 1.

The first magnet 41a is fitted into the first accommodation hole 31 a. More specifically, the first magnet 41a is fitted in 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, for example, the inner side surfaces of the first straight line portion 31c, respectively. The length of the first magnet 41a is, for example, the same as the length of the first linear portion 31c in the direction in which the first linear portion 31c extends, as viewed in the axial direction.

When viewed in the axial direction, both ends of the first magnet 41a in the extending direction are disposed apart from both ends of the first housing hole 31a in the extending 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 to sandwich 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 to sandwich the first magnet 41b in a direction in which the first magnet 41b extends, as viewed in the axial direction.

As described above, when viewed in the axial direction, the rotor core 20 includes the first magnetic flux shielding portions 51a, 51b, 51c, and 51d, which are arranged in a pair with the first magnets 41a and 41b interposed therebetween in the direction in which the first magnets 41a and 41b extend. The first magnetic flux shielding portions 51a, 51b, 51c, and 51d, the second magnetic flux shielding portions 52a and 52b described later, and the groove 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 portion and the groove portion. 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 accommodation hole 32 when viewed in the axial direction. The second magnet 42 extends in a direction orthogonal to the radial direction when viewed in the axial direction. The pair of first magnets 41a, 41b and the second magnet 42 are arranged along a # -shape when viewed in the axial direction, for example.

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

The shape of the second magnet 42 when viewed in the axial direction is, for example, a shape that is line-symmetrical with respect to the magnetic pole center line IL 1. The second magnet 42 has a rectangular shape when viewed in the axial direction, for example. Although not shown, the second magnet 42 is, for example, rectangular parallelepiped. Although not shown, the second magnet 42 is provided in the entire axial direction in the second accommodation 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 accommodation hole 32. More specifically, the second magnet 42 is fitted in the second linear portion 32 a. Of the side surfaces of the second magnet 42, the radial side surfaces orthogonal to the direction in which the second linear portion 32a extends are in contact with, for example, the inner side surfaces of the second linear portion 32a, respectively. The length of the second magnet 42 in the direction in which the second linear portion 32a extends, for example, is the same as the length of the second linear portion 32a when viewed in the axial direction.

The second magnet 42 is disposed so as to be apart from both ends of the second housing hole 32 in the extending direction when 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 a 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 to sandwich 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 first magnetic flux shielding portion 51b located radially outward of the pair of first magnetic flux shielding portions 51a and 51b sandwiching the first magnet 41a and the circumferential direction of the first magnetic flux shielding portion 51d located radially outward 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 of the first magnet 41a located radially outward, the magnetic pole of the first magnet 41b located radially outward, and the magnetic pole of the second magnet 42 located radially outward 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 pole of the first magnet 41a, a magnetic pole located radially outward of the magnetic pole of the first magnet 41b, and a magnetic pole located radially outward of the magnetic pole of the second magnet 42 are, for example, N poles. In the magnetic pole portion 70N, for example, 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 S-poles.

Although not shown, the poles of the magnets 40 are arranged in the pole portions 70S in a reverse manner with respect to the pole portions 70N. That is, in the magnetic pole portion 70S, the magnetic pole located radially outward of the magnetic pole of the first magnet 41a, the magnetic pole located radially outward of the magnetic pole of the first magnet 41b, and the magnetic pole located radially outward of the magnetic pole 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 is disposed at the same circumferential position as the circumferential center of one of the teeth 63, the teeth 63 in which the circumferential center is disposed 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 when 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, rotor core 20 has slot 80. The groove 80 has a pair of grooves 80A and 80B. The groove 80A and the groove 80B are recessed radially inward from the outer peripheral surface 20A, respectively, when viewed in the axial direction. The slot 80A and the slot 80B pass through the rotor core 20 in the axial direction. The groove 80A and the groove 80B are provided along the q-axis IL2 when viewed in the axial direction. The q-axis IL2 is an axis extending electrically in a right angle direction with respect to the d-axis.

Fig. 4 is an enlarged cross-sectional view of the periphery of the groove 80 radially opposed to the teeth 66F. As shown in fig. 4, the groove 80A and the groove 80B are provided at intervals on both sides in the circumferential direction sandwiching the q-axis IL 2. In other words, the groove 80 has a groove 80A and a groove 80B extending in the circumferential direction at intervals of the q-axis IL2 when viewed in the axial direction. Groove 80A is located on one side in the circumferential direction of q-axis IL 2. The groove 80B is located on the other side in the circumferential direction of the q-axis IL 2. The groove 80A and the groove 80B are arranged, for example, line-symmetrically with respect to the q-axis IL2 when viewed in the axial direction. Hereinafter, the groove 80B may be omitted from the same structure as the groove 80A except for the point of line symmetry with respect to the q-axis IL 2.

By providing the groove 80 located on the q-axis IL2 when viewed in the axial direction, the radial electromagnetic excitation force at the time of high-speed rotation can be reduced, and radial vibration of the electrical angle 12 times due to the radial electromagnetic excitation force can be suppressed. When the groove 80A and the groove 80B include the positions of the q-axis IL2 and are continuously provided at intervals in the circumferential direction, the circumferential electromagnetic excitation force increases during low-speed rotation. According to the present embodiment, the groove portions 80A and 80B are provided at intervals on both sides in the circumferential direction of the q-axis IL2, and as shown in fig. 3, the outer peripheral surface 20A of the rotor core 20 in which the groove portions 80A and 80B are not provided in a certain state faces the teeth 66F and 66G in the radial direction. Therefore, by securing a magnetic circuit of the magnetic flux flowing radially inward from the teeth 66F and 66G, the circumferential electromagnetic excitation force at the time of low-speed rotation can be reduced, and radial vibration of the electrical angle 12 times due to the circumferential electromagnetic excitation force can be suppressed. As an example, high-speed rotation means that the rotational speed of the motor (rotor core 20) is 5000 (rpm) or more. As an example, low-speed rotation means that the rotational speed of the motor (rotor core 20) is less than 5000 (rpm).

As shown in fig. 4, when the maximum radial dimensions of the groove portions 80A and 80B are L1 and the minimum circumferential spacing between the pair of groove portions 80A and 80B is L2, the relationship of 0.8 (L2/L1) to 1.2 is satisfied. If the value represented by (L2/L1) is smaller than 0.8, the magnetic paths of the magnetic fluxes flowing radially inward from the teeth 66F and 66G become narrower, and there is a possibility that the decrease in the circumferential electromagnetic excitation force at the time of low-speed rotation becomes insufficient. If the value represented by (L2/L1) exceeds 1.2, the radial electromagnetic excitation force may be insufficiently reduced at the time of high-speed rotation. By setting the value represented by (L2/L1) to 0.8 or more and 1.2 or less, the circumferential electromagnetic excitation force at the time of low-speed rotation and the radial electromagnetic excitation force at the time of high-speed rotation can be sufficiently reduced.

In the rotating electrical machine 1, the circumferential electromagnetic excitation force becomes a noise source during low-speed rotation, and the radial electromagnetic excitation force becomes a noise source during high-speed rotation. According to the present embodiment, by satisfying the relationship of 0.8 (L2/L1) to 1.2 by the maximum dimension L1 in the radial direction of the groove portion 80A and the groove portion 80B and the minimum dimension L2 of the interval between the groove portions 80A and 80B in the circumferential direction, the circumferential electromagnetic excitation force at the time of low-speed rotation and the radial electromagnetic excitation force at the time of high-speed rotation can be reduced, and noise can be reduced from the time of low-speed rotation to the time of high-speed rotation without depending on the rotation speed of the motor.

[ relation between the rotation speed and the increase/decrease ratio of 12 electromagnetic excitation forces ]

Fig. 5 is a diagram showing a relationship between the rotational speed of the motor (rotor core 20) and the increasing/decreasing ratio of the 12 radial electromagnetic excitation forces. The ratio of increase/decrease in the electric angle 12 times radial electromagnetic excitation force with respect to the electric angle 12 times radial electromagnetic excitation force in the rotary electric machine in which the groove 80 is not provided is expressed as "2 grooves" in the rotary electric machine having the groove 80A and the groove 80B. In fig. 5, "1 slot" indicates an increase/decrease ratio of 12 times of radial electromagnetic excitation force at an electrical angle in a rotary electric machine having a slot portion 80C, and as shown in fig. 8, the slot portion 80C has a circumferential center on the q-axis IL2, a maximum radial dimension L1 of 1.0mm, and a circumferential slot width L3 of 2.0mm. The groove portion 80A of "2 grooves" and the groove portion 80B satisfy the above-mentioned relationship of 0.8.ltoreq.L 2/L1.ltoreq.1.2.

Fig. 6 is a diagram showing a relationship between the rotational speed of the motor (rotor core 20) and the increasing/decreasing ratio of 12 times of circumferential electromagnetic excitation force. The increase/decrease ratio of the electric angle 12 times circumferential electromagnetic excitation force with respect to the electric angle 12 times circumferential electromagnetic excitation force in the rotary electric machine in which the groove portion 80 is not provided is represented by "2 grooves" in the electric angle 12 times circumferential electromagnetic excitation force in the rotary electric machine having the groove portions 80A and 80B, and the increase/decrease ratio of the electric angle 12 times circumferential electromagnetic excitation force in the rotary electric machine in which the groove portion 80C is represented by "1 groove" is represented by "2 grooves". The groove portion 80A of "2 grooves" and the groove portion 80B satisfy the above-mentioned relationship of 0.8.ltoreq.L 2/L1.ltoreq.1.2.

As shown in fig. 5, by providing both the "2 grooves" in which the groove portions 80A and 80B are provided and the "1 groove" in which the groove portion 80C is provided, the radial electromagnetic excitation force at the time of high-speed rotation can be reduced as compared with the rotary electric machine in which the groove portion 80 is not provided.

As shown in fig. 6, the circumferential electromagnetic excitation force at the time of low-speed rotation is equal to that of the rotating electrical machine in which the groove portions 80 are not provided, for the "2 grooves" in which the groove portions 80A and 80B are provided. The "1 groove" provided with the groove portion 80C increases the circumferential electromagnetic excitation force at the time of low-speed rotation as compared with the rotating electrical machine not provided with the groove portion 80.

According to the present embodiment, by satisfying the relationship of 0.8 (L2/L1) to 1.2 between the groove portion 80A and the groove portion 80B, the circumferential electromagnetic excitation force at the time of low-speed rotation is equal to that of a rotating electrical machine in which the groove portion 80 is not provided, and the radial electromagnetic excitation force at the time of high-speed rotation can be reduced as compared to that of a rotating electrical machine in which the groove portion 80 is not provided.

The groove portion 80A has first straight portions 81, 82, second straight portions 83, and curved portions 84, 85 when viewed in the axial direction. The first linear portions 81 and 82 extend linearly inward in the radial direction from the outer peripheral surface 20 a. The first straight line portion 81 is farther from the q-axis IL2 in the circumferential direction than the first straight line portion 82. The first straight line portion 82 is closer to the q-axis IL2 in the circumferential direction than the first straight line portion 81. The second linear portion 83 is located radially inward of the first linear portions 81 and 82, and extends linearly in the circumferential direction. The curved portion 84 is arcuate, and connects the first linear portion 81 and the second linear portion 83. The curved portion 85 is arc-shaped, and connects the first straight portion 82 and the second straight portion 83.

According to the present embodiment, the first linear portion 81 and the second linear portion 83 are connected by the arcuate curved portion 84, so that the stress concentration at the intersection of the first linear portion 81 and the second linear portion 83 can be relaxed. According to the present embodiment, the first linear portion 82 and the second linear portion 83 are connected by the arcuate curved portion 85, so that the stress concentration at the intersection of the first linear portion 82 and the second linear portion 83 can be relaxed.

In the groove 80A, the distance in the circumferential direction from the q-axis IL2 to the farthest portion (the radially outer end of the first straight portion 81) is shorter than the shortest distance in the circumferential direction between the radially outer magnetic flux shielding portion 51d and the q-axis IL 2. In the groove 80B, the distance in the circumferential direction from the q-axis IL2 to the farthest position is shorter than the shortest distance between the magnetic flux shielding portion 51B located radially outward and the q-axis IL2 in the circumferential direction.

In the groove 80A, the distance in the circumferential direction from the q-axis IL2 to the farthest position is shorter than the shortest distance in the circumferential direction between the magnetic flux shielding portion 51d located radially outward and the q-axis IL2, whereby the flow of the magnetic flux can be blocked by the narrowing of the magnetic path between the groove 80A and the magnetic flux shielding portion 51d, and the average torque can be suppressed from decreasing. In the groove 80B, the distance in the circumferential direction from the q-axis IL2 to the farthest position is shorter than the shortest distance in the circumferential direction between the magnetic flux shielding portion 51B located radially outward and the q-axis IL2, whereby the narrowing of the magnetic path between the groove 80B and the magnetic flux shielding portion 51B can be suppressed to block the flow of the magnetic flux, and the average torque reduction can be suppressed.

[ relation between the number of grooves and the ratio of increase/decrease in electromagnetic excitation force 12 times with respect to the average torque and electric angle ]

Fig. 7 is a graph showing a relationship between the number of grooves and the increasing/decreasing ratio of the average torque, and showing a relationship between the number of grooves and the increasing/decreasing ratio of the electromagnetic excitation force 12 times at the electrical angle. In fig. 7, the rotary electric machine in which the groove portion 80 is not provided is indicated as "no groove". As shown in fig. 8, "1 groove" means a rotating electrical machine having a groove portion 80C with a maximum radial dimension L1 of 1.0mm and a circumferential groove width L3 of 4.0 mm. "2 grooves" means a rotating electrical machine in which the groove portions 80A and 80B are provided such that the maximum dimension L1 in the radial direction is 1.0mm, the minimum dimension L2 of the circumferential space between the groove portions 80A and 80B is 1.0mm, and the circumferential groove width L3 is 4.0 mm.

As shown in fig. 7, the average torque is equal to a value without a large difference in any of the rotating electrical machines of "no slot", "1 slot", and "2 slots". The ratio of increase/decrease in the electromagnetic excitation force in the radial direction at the electrical angle of 12 times can be reduced in the case of any of the rotating electrical machines of "1 slot" and "2 slots" as compared with the rotating electrical machine in which the slot portion 80 is not provided. The increase/decrease ratio of the electromagnetic excitation force in the circumferential direction of the electrical angle 12 times is increased in the case of the "1-slot" rotating electric machine, and is decreased in the case of the "2-slot" rotating electric machine, compared to the "no-slot" rotating electric machine.

Fig. 9 is a diagram showing a relationship between a groove width L3 and each increase/decrease ratio of an average torque, an electric angle 12 times radial electromagnetic excitation force, and an electric angle 12 times circumferential electromagnetic excitation force in a rotary electric machine having the groove portion 80C of "1 groove" shown in fig. 8, with respect to a "slotless" rotary electric machine. In fig. 9, the maximum dimension L1 in the radial direction is fixed to 1.0mm, and the radius of the arcuate curve portion is fixed to 1.0mm.

As shown in fig. 9, in the case of the "1-slot" rotating electrical machine, the average torque increasing/decreasing ratio is equal to the average torque value without depending on the value of the slot width L3 and without a large difference. In the case of a "1 slot" rotating electrical machine, the larger the slot width L3, the lower the ratio of increase/decrease in the 12-time radial electromagnetic excitation force of the electrical angle, with the slot width L3 having a value of 2.0 to 4.0 mm. In the case of a rotating electrical machine having "1 slot", the larger the value of the slot width L3 is, the larger the increase/decrease ratio of the 12-time circumferential electromagnetic excitation force at the electrical angle is. Therefore, in the case of a rotating electrical machine of "1 slot", it is difficult to reduce the increase/decrease ratio of the circumferential electromagnetic excitation force 12 times at the electrical angle.

Fig. 10 is a diagram showing a relationship between a groove width L3 and each increasing/decreasing ratio of average torque, 12 times of electric angle radial electromagnetic excitation force, and 12 times of electric angle circumferential electromagnetic excitation force in a rotary electric machine having the groove portions 80A and 80B of "2 grooves" shown in fig. 4, with respect to the "slotless" rotary electric machine. In fig. 10, the minimum dimension L2 of the circumferential interval between the grooves 80A and 80B is set to 1.0mm, and the maximum dimension L1 in the radial direction and the radius of the arcuate curve portion are set to 1.0mm.

As shown in fig. 10, in the case of the "2-slot" rotating electrical machine, the average torque increasing/decreasing ratio is equal to the average torque value without depending on the value of the slot width L3 and without a large difference. In the case of a "two-slot" rotating electrical machine, the larger the slot width L3, the lower the electric angle 12-time radial electromagnetic excitation force increasing/decreasing ratio, with the slot width L3 having a value of 2.0 to 4.0 mm. In the case of a "2 slot" rotating electrical machine, the increase/decrease ratio of the electrical angle 12 times circumferential electromagnetic excitation force is increased compared to a "no slot" rotating electrical machine when the value of the slot width L3 is between 2.0 and 2.5mm, and the increase/decrease ratio of the electrical angle 12 times circumferential electromagnetic excitation force is decreased compared to a "no slot" rotating electrical machine when the value of the slot width L3 is more than 2.5mm and 4.0mm or less. Therefore, in the case of a rotating electrical machine having "2 slots", the increase/decrease ratio of the electromagnetic excitation force in the circumferential direction at the electrical angle 12 times can be reduced by setting the value of the slot width L3 to, for example, 3.0mm or more and 4.0mm or less.

Fig. 11 is a diagram showing a relationship between a circumferential interval L2 between the groove portions 80A and 80B and each of the average torque, the electric angle 12 times of radial electromagnetic excitation force, and each increasing/decreasing ratio of the electric angle 12 times of circumferential electromagnetic excitation force in the rotating electric machine having the groove portions 80A and 80B of "2 grooves" with respect to the rotating electric machine having the "slotless" described above. In fig. 11, the groove width L3 was set to 2.0mm, and the maximum radial dimension L1 and the radius of the arcuate curve were set to 1.0mm.

As shown in fig. 11, in the case of the "2-slot" rotating electrical machine, the average torque increase/decrease ratio is equal to or less than the value of the circumferential interval L2 and is not dependent on the value of the circumferential interval L2, but is equal to or less than the value of the circumferential interval L2. In the case of a "2 slot" rotating electrical machine, the electrical angle 12 times the ratio of increase/decrease in radial electromagnetic excitation force is lower than that of a "no slot" rotating electrical machine, with the value of the circumferential interval L2 being between 0.2 and 1.2 mm. In the case of a "2 slot" rotating electrical machine, the increase/decrease ratio of the electrical angle 12 times in the circumferential direction electromagnetic excitation force increases compared to a "no slot" rotating electrical machine, while the increase ratio is smallest when the value of the circumferential direction interval L2 is between 0.2 and 1.2mm, and the value of the circumferential direction interval L2 is 1.0mm. Therefore, in the case of a rotating electrical machine having "2 slots", the increase/decrease ratio of the electromagnetic excitation force in the circumferential direction at the electrical angle of 12 times can be suppressed by setting the value of the interval L2 in the circumferential direction to, for example, 1.0mm.

While the preferred embodiments of the present invention have been described above with reference to the drawings, 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 merely examples, and various modifications can be made based on design requirements and the like without departing from the scope of the present invention.

For example, in the above embodiment, the v-shaped magnet 40 having the first magnets 41a, 41b and the second magnet 42 is illustrated, but the present invention is not limited to this configuration. For example, the magnet 40 may be a rotary electric machine 1 having a structure in which the pole piece is adjacent to the first magnets 41a and 41b arranged in a V-shape without the second magnet 42. 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 magnet pole pieces are arranged at intervals in the radial direction, the groups being adjacent to the first magnets 41a and 41b, without the second magnet 42.

Claims (4)

1. An electric rotating machine, comprising:

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 which are respectively accommodated in the plurality of accommodating 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 circumferentially spaced intervals; and

a plurality of coils mounted to the stator core,

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

the rotor core has a pair of groove portions recessed inward in the radial direction on both sides of the q-axis in the circumferential direction of the outer peripheral surface at intervals when viewed in the axial direction,

when the maximum dimension in the radial direction of the slot portion is set to L1 and the minimum dimension in the circumferential direction of the interval between the pair of slot portions is set to L2, the rotor core satisfies a relationship of 0.8.ltoreq.L 2/L1.ltoreq.1.2.

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

the groove portion has, when viewed in the axial direction:

a first linear portion extending linearly from the outer peripheral surface to the radially inner side;

a second linear portion located radially inward of the first linear portion and extending linearly in a circumferential direction; and

and an arc-shaped curved portion connecting the first straight portion and the second straight portion.

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

the rotor core has a pair of magnetic flux shielding portions arranged so as to sandwich the magnet in a direction in which the magnet extends when viewed in the axial direction,

the distance from the q-axis to the farthest position in the groove is shorter than the shortest distance between the q-axis and the magnetic flux shielding portion located radially outward of the pair of magnetic flux shielding portions.

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

the plurality of magnets includes:

a pair of first magnets arranged at a distance from each other in the circumferential direction and extending in a direction away from each other in the circumferential direction as seen in the axial direction from the radially inner side toward the radially outer side; and

and a second magnet which is disposed at a circumferential position between the pair of first magnets on the radially outer side than the radially inner ends of the pair of first magnets, and which extends in a direction orthogonal to the radial direction when viewed in the axial direction.