WO2014112021A1

WO2014112021A1 - Motor

Info

Publication number: WO2014112021A1
Application number: PCT/JP2013/007566
Authority: WO
Inventors: Tomoya Ueda
Original assignee: Nidec Corporation
Priority date: 2013-01-15
Filing date: 2013-12-25
Publication date: 2014-07-24
Also published as: CN103929032A; BR112015016838A2; JP2014138433A; DE112013006430T5; US9966809B2; US20160020653A1; JP6128419B2; CN103929032B

Abstract

A rotor of an electrical rotating machine includes a first rotor core, a second rotor core which overlaps the first rotor core in an axial direction, a non-magnetic substance layer which is interposed between the rotor cores, and a plurality of permanent magnet portions which are embedded in each rotor core. Each of the rotor cores includes a plurality of flux barrier portions and a plurality of effectual magnetic flux portions which are alternately arranged on an outer circumferential surface thereof. The flux barrier portion of the first rotor core overlaps both of a part of the flux barrier portion of the second rotor core and a part of the effectual magnetic flux portion of the second rotor core, in the axial direction. As a result, in the adjacent rotor cores, the effectual magnetic flux portions of which magnetic poles on the radially outer sides are different from each other do not overlap each other in the axial direction. Thereby, short-circuiting of the magnetic flux is prevented from occurring between the adjacent rotor cores.

Description

MOTOR

The present invention relates to an electrical rotating machine.

A permanent magnet embedded type electrical rotating machine having a rotor core provided with an embedded permanent magnet has been known in the related art. In addition, as a method to reduce cogging torque and torque ripple of the electrical rotating machine, a magnetic pole of a rotor or a stator has been arranged with inclination with respect to an axial direction, in the related art. A so-called skew structure is generally known.

A permanent magnet embedded type electrical rotating machine having a skew structure in the related art has been disclosed in JP-A 2000-308287, for example. In a motor disclosed in JP-A 2000-308287, a plurality of rotor core blocks provided with embedded permanent magnets are integrally formed in an axial direction while being deviated from each other in a rotation direction of a rotor (see Claim 1, Paragraph 0014).

[PTL 1] JP-A 2000-308287

In the motor disclosed in JP-A 2000-308287, an N-pole embedded in an rotor core block on an upper side and an S-pole embedded in an rotor core block on a lower side overlap each other in the rotational-axial direction, in two rotor core blocks adjacent to each other in the axial direction (see Fig. 1, Paragraph 0015). Therefore, magnetic flux leaving the N-pole on the upper side enters the S-pole on the lower side. The magnetic flux forms a short circuit loop inside the rotor, without being cross-linked with a stator outside the rotor. Therefore, torque is reduced (see Paragraph 0009). That is, effectual magnetic flux of the rotor is reduced. In the motor according to the publication, a non-magnetic substance having a thin plate shape is interposed between the rotor core blocks, in order to suppress magnetic flux flowing from the N-pole on the upper side to the S-pole on the lower side (see Paragraph 0015). However, if the N-pole on the upper side and the S-pole on the lower side overlap each other in the rotational axial direction, as in the motor according to the publication, it is difficult to further suppress the reduction in the effectual magnetic flux.

An object of the present invention is to provide a technique capable of suppressing the reduction in effectual magnetic flux of a rotor core, in a permanent magnet embedded type electrical rotating machine provided with a rotor core having a skew structure.

According to a first exemplary aspect of the present application, there is provided an electrical rotating machine having a rotor which rotates about a central axis and has a substantially cylindrical shape. The rotor includes a first rotor core and a second rotor core which overlaps the first rotor core in an axial direction. The rotor includes a non-magnetic substance layer which is interposed between the first rotor core and the second rotor core, and a plurality of permanent magnet portions which are embedded in the first rotor core and the second rotor core. In each of the first rotor core and the second rotor core, the plurality of permanent magnet portions are arranged at substantially equal intervals in a circumferential direction. In two permanent magnet portions adjacent to each other in the circumferential direction, magnetic poles of radially outer surfaces thereof are different from each other. Each of the first rotor core and the second rotor core has a stage skew structure in which the plurality of the permanent magnet portions thereof are arranged so as to be deviated from each other in the circumferential direction. Each of the first rotor core and the second rotor core includes a plurality of flux barrier portions and a plurality of effectual magnetic flux portions. The plurality of flux barrier portions are magnetically saturated between the magnetic poles of the permanent magnet portions adjacent to each other in the circumferential direction. The plurality of effectual magnetic flux portions are disposed on a radially outer side of the permanent magnet portions and function as a magnetic path between the permanent magnet portions and an outside of the rotor. The plurality of the flux barrier portions and the plurality of the effectual magnetic flux portions are arranged alternately in the circumferential direction on an outer circumferential surface of each of the first rotor core and the second rotor core. The flux barrier portion of the first rotor core overlaps both of a part of the flux barrier portion of the second rotor core and a part of the effectual magnetic flux portion of the second rotor core, in the axial direction.

According to the first exemplary aspect of the present application, a part of the flux barrier portion of the first rotor core and a part of the flux barrier portion of the second rotor core overlap each other in the axial direction, in the first rotor core and the second rotor core adjacent to each other in the axial direction. Thereby, the effectual magnetic flux portion of the first rotor core and the effectual magnetic flux portion of the second rotor core of which the magnetic pole is different from that of the first rotor core do not overlap each other in the axial direction. As a result, short-circuiting of the magnetic flux is prevented from occurring between the rotor cores adjacent to each other in the axial direction. That is, reduction in the effectual magnetic flux of the rotor core is suppressed.

Fig. 1 is a perspective view of a rotor according to a first embodiment. Fig. 2 is a longitudinal cross-sectional view of an electrical rotating machine according to a second embodiment. Fig. 3 is a perspective view of a rotor according to the second embodiment. Fig. 4 is a top view of a rotor unit according to the second embodiment. Fig. 5 is a partial top view of the rotor unit according to the second embodiment. Fig. 6 is a partial top view of the rotor according to the second embodiment. Fig. 7 is a perspective view of a rotor according to a modification example. Fig. 8 is a perspective view of a rotor according to another modification example. Fig. 9 is a top view of a rotor unit according to another modification example. Fig. 10 is a top view of a rotor unit according to another modification example. Fig. 11 is a perspective view of a rotor according to another modification example.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. Furthermore, in the present application, a direction parallel to a central axis of an electrical rotating machine is designated as "axial direction", a direction perpendicular to the central axis of the electrical rotating machine is designated as "radial direction", and a direction along an arc centering on the central axis of the electrical rotating machine is designated as "circumferential direction". In addition, in the present application, a shape and a positional relationship of each part will be described while the axial direction is set as an up-down direction and a lid portion side in housing is set as an upper side. However, definition of the up-down direction is not intended to limit the orientation at the time of using the electrical rotating machine according to the present invention.

Furthermore, "parallel direction" in the present application also includes a substantially parallel direction. In addition, "perpendicular direction" in the present application also includes a substantially perpendicular direction.

<1. First Embodiment>
Fig. 1 is a perspective view of a rotor 32A of an electrical rotating machine according to a first embodiment. As shown in Fig. 1, the rotor 32A has a substantially cylindrical shape and rotates about a central axis 9A. The rotor 32A has a first rotor core 510A, a second rotor core 520A, a non-magnetic substance layer 50A and a plurality of permanent magnet portions 320A.

The first rotor core 510A and the second rotor core 520A overlap each other in an axial direction. The non-magnetic substance layer 50A is interposed between the first rotor core 510A and the second rotor core 520A.

Each of the permanent magnet portions 320A constitutes a single magnetic pole toward a radially outer side. In the embodiment, each of the plurality of permanent magnet portions 320A is constituted by a single piece of permanent magnet 61A. That is, each of a plurality of permanent magnets 61A constitutes a permanent magnet portion 320A.

The plurality of permanent magnets 61A are embedded in the first rotor core 510A and the second rotor core 520A. The plurality of permanent magnets 61A are arranged at substantially equal intervals in a circumferential direction, in each of the first rotor core 510A and the second rotor core 520A.

Furthermore, the plurality of permanent magnets 61A includes a plurality of permanent magnets 611A of which a radially outer surface is an N-pole and a plurality of permanent magnets 612A of which a radially outer surface is an S-pole. The permanent magnets 611A and the permanent magnets 612A are arranged alternately in the circumferential direction. That is, in the

permanent magnets

611A and 612A adjacent to each other in the circumferential direction, magnetic poles of radially outer surfaces thereof are different from each other.

According to the configuration described above, the first rotor core 510A and the second rotor core 520A respectively have a plurality of flux barrier portions 62A and a plurality of effectual magnetic flux portions 63A. The flux barrier portions 62A and the effectual magnetic flux portions 63A are arranged alternately in the circumferential direction on an outer circumferential surface of each of the first rotor core 510A and the second rotor core 520A.

Each of the plurality of the flux barrier portions 62A is magnetically saturated between the magnetic poles of the

permanent magnets

611A and 612A adjacent to each other in the circumferential direction.

Each of the plurality of effectual magnetic flux portions 63A is disposed on a radially outer side of each permanent magnet 61A. The effectual magnetic flux portion 63A functions as a magnetic path between the permanent magnet 61A disposed on a radially inner side and an outside of the rotor 32A. Thereby, each of the plurality of effectual magnetic flux portions 63A has an N-pole magnetic flux portion 631A and an S-pole magnetic flux portion 632A. A radially outer surface of the N-pole magnetic flux portion 631A is an N-pole. A radially outer surface of the S-pole magnetic flux portion 632A is an S-pole. The N-pole magnetic flux portion 631A is disposed on a radially outer side of the permanent magnet 611A of which a magnetic pole of a radially outer surface is an N-pole. In addition, the S-pole magnetic flux portion 632A is disposed on a radially outer side of the permanent magnet 612A of which a magnetic pole of a radially outer surface is an S-pole. Therefore, a plurality of N-pole magnetic flux portions 631A and a plurality of S-pole magnetic flux portions 632A are arranged alternately in the circumferential direction. That is, in the plurality of N-pole magnetic flux portions 631A and the plurality of S-pole magnetic flux portions 632A, magnetic poles on the radially outer sides of two effectual magnetic flux portions 63A which are adjacent to each other in the circumferential direction and interpose the flux barrier portion 62A therebetween are different from each other.

The first rotor core 510A and the second rotor core 520A are disposed at a position where the permanent magnets 61A thereof are deviated from each other in the circumferential direction. Thereby, the flux barrier portion 62A of the first rotor core 510A and the flux barrier portion 62A of the second rotor core 520A are arranged so as to be deviated from each other in the circumferential direction, as shown in Fig. 1. Similarly, the effectual magnetic flux portion 63A of the first rotor core 510A and the effectual magnetic flux portion 63A of the second rotor core 520A are arranged so as to be deviated from each other in the circumferential direction. That is, the rotor 32A has a so-called stage skew structure, thereby, reducing the cogging torque and the torque ripple of the electrical rotating machine.

In addition, the deviation between the first rotor core 510A and the second rotor core 520A in the circumferential direction which is due to the stage skew structure has an extent where the effectual magnetic flux portion 63A of the first rotor core 510A and the effectual magnetic flux portion 63A of the second rotor core 520A having a different magnetic pole do not overlap each other in the axial direction.

In the stage skew structure described above, the flux barrier portion 62A of the first rotor core 510A overlaps a part of the effectual magnetic flux portion 63A of the second rotor core 520A in the axial direction. Similarly, the flux barrier portion 62A of the second rotor core 520A overlaps a part of the effectual magnetic flux portion 63A of the first rotor core 510A.

Meanwhile, the non-magnetic substance layer 50A is interposed between the first rotor core 510A and the second rotor core 520A, as described above. Thereby, short-circuiting of the magnetic flux is prevented between the flux barrier portion 62A of the first rotor core 510A and the effectual magnetic flux portion 63A of the second rotor core 520A. Similarly, short-circuiting of the magnetic flux is prevented between the effectual magnetic flux portion 63A of the first rotor core 510A and the flux barrier portion 62A of the second rotor core 520A. That is, reduction in the effectual magnetic flux of the rotor 32A is suppressed.

In addition, a part of the flux barrier portion 62A of the first rotor core 510A and a part of the flux barrier portion 62A of the second rotor core 520A overlap each other in the axial direction. Thereby, the N-pole magnetic portion 631A of the first rotor core 510A and the S-pole magnetic flux portion 632A of the second rotor core 520A do not overlap each other in the axial direction. Similarly, the S-pole magnetic portion 632A of the first rotor core 510A and the N-pole magnetic flux portion 631A of the second rotor core 520A do not overlap each other in the axial direction. That is, the effectual magnetic flux portions 63A which are on the radially outer side and have magnetic poles different from each other do not overlap each other, in the adjacent rotor cores. As a result, short-circuiting of the magnetic flux is further prevented from occurring in the adjacent rotor cores. That is, reduction in the effectual magnetic flux of the rotor 32A is further suppressed.

<2. Second Embodiment>
<2-1. Whole Structure of Motor>
Subsequently, a second embodiment of the present invention will be described.

Fig. 2 is a longitudinal cross-sectional view of a motor 1 according to the second embodiment. The motor 1 of the embodiment is mounted on a vehicle. The motor 1 of the embodiment is used to generate a driving force for a steering device. However, the motor 1 of the present invention may be adopted to an apparatus aside from a vehicle.

As shown in Fig. 2, the motor 1 has a static section 2 and a rotation section 3. The rotation section 3 is rotatably supported by the static section 2.

The static section 2 of the embodiment has a housing 21, a lid portion 22, a stator 23, a lower bearing portion 24 and an upper bearing portion 25.

The housing 21 has a side wall 211 having a substantially cylindrical shape and a bottom portion 212 to close a lower portion of the side wall. The lid portion 22 covers an upper opening of the housing 21. The stator 23 and a rotor 32 described later are accommodated in an internal space surrounded by the housing 21 and the lid portion 22. The lower bearing portion 24 is disposed in a center of the bottom portion 212 of the housing 21. In addition, the upper bearing portion 25 is disposed in a center of the lid portion 22.

The stator 23 is an armature which generates magnetic flux corresponding to driving current. The stator 23 has a stator core 41, an insulator 42 and a coil 43. The stator core 41 is constituted by a lamination steel sheet of laminating a plurality of electrical steel sheets in the axial direction, for example. The stator core 41 has a core back 411 having an annular shape and a plurality of teeth 412 protruding from the core back 411 on a radial direction inner side. The core back 411 is fixed to an inner circumferential surface of the side wall 211 of the housing 21. The plurality of teeth 412 are arranged at substantially equal intervals in the circumferential direction.

The insulator 42 is made of resin of an insulating material. The insulator 42 covers upper and lower surfaces of each of teeth 412 and both end surfaces thereof in the circumferential direction. The coil 43 is constituted by a lead wire wound around the insulator 42. The insulator 42 is interposed between the teeth 412 and the coil 43. Therefore, electrical short-circuiting is prevented from occurring between the teeth 412 and the coil 43. Furthermore, insulating coating may be applied to the surface of the teeth 412, instead of the insulator 42.

The lower bearing portion 24 and the upper bearing portion 25 are respectively disposed between the housing 21 and a shaft 31 on a rotation section 3 side, and between the lid portion 22 and a shaft 31 on a rotation section 3 side, which is described below. Thereby, the shaft 31 is rotatably supported by the housing 21 and the lid portion 22. A ball bearing of which an inner ring and an outer ring relatively rotate via a spherical body is used as the lower bearing portion 24 and the upper bearing portion 25 of the embodiment. However, other types of bearing such as a slide bearing or a liquid bearing may be used as the lower bearing portion 24 and the upper bearing portion 25 of the embodiment, instead of the ball bearing.

The rotation section 3 of the embodiment has the shaft 31 and the rotor 32.

The shaft 31 is a columnar member extending along a central axis 9. The shaft 31 is supported by the lower bearing portion 24 and the upper bearing portion 25, while rotating around the central axis 9. In addition, an upper end portion of the shaft 31 protrudes further in the upper direction than the lid portion 22, as shown in Fig. 2. The upper end portion of the shaft 31 is connected to a steering device of a vehicle via a power transmission mechanism such as gears, for example. Furthermore, the upper end portion of the shaft 31 may be connected to driving portions other than the steering device.

In addition, the shaft 31 protrudes further in the upper direction than the lid portion 22, in the embodiment. However, the present invention is not limited thereto. The shaft 31 may protrude further in the lower direction than the bottom portion 212 of the housing 21 and an lower end portion of the shaft 31 may be connected to the driving portion.

The rotor 32 is disposed on the inner side of the stator 23 in the radial direction. The rotor 32 and the shaft 31 rotate together. A detailed structure of the rotor 32 will be described below.

In the motor 1 described above, if driving current is applied to the coil 43 of the static section 2, magnetic flux in the radial direction is generated in the plurality of teeth 412 of the stator core 41. Therefore, torque in the circumferential direction is generated by the action of the magnetic flux between the teeth 412 and the rotor 32. As a result, the rotation section 3 rotates about the central axis, with respect to the static section 2. If the rotation section 3 rotates, a driving force is transmitted to the steering device connected to the shaft 31.

<2-2. Structure of Rotor>
Next, the detailed structure of the rotor 32 will be described. Fig. 3 is a perspective view of the rotor 32. Fig. 4 is a top view of a first rotor unit 51. Fig. 5 is a partial top view of the first rotor unit 51. Fig. 6 is a partial top view of the rotor 32.

As shown in Fig. 3, the rotor 32 has a substantially cylindrical shape. The rotor 32 has the first rotor unit 51, a second rotor unit 52 and a non-magnetic substance layer 50. The first rotor unit 51 and the second rotor unit 52 overlap each other in the axial direction. In addition, the non-magnetic substance layer 50 is interposed between the first rotor unit 51 and the second rotor unit 52.

As shown in Fig. 4, the first rotor unit 51 has a first rotor core 510 and a plurality of permanent magnet portions 320.

The first rotor core 510 is a tubular-shaped member surrounding the shaft 31. The first rotor core 510 of the embodiment is constituted by a lamination steel sheet of laminating electrical steel sheets in the axial direction. A shaft hole 71, a plurality of magnet holes 72 and a plurality of non-magnetic holes 73 which respectively penetrate the first rotor core 510 in the axial direction are provided in the first rotor core 510.

Each of the permanent magnet portions 320 forms a single magnetic pole toward the radially outer side. Each of the plurality of permanent magnet portions 320 is constituted by a single piece of permanent magnet 61. That is, each of a plurality of permanent magnets 61 constitutes a permanent magnet portion 320.

As shown in Fig. 4, the shaft hole 71 is provided in a center of the first rotor core 510, and the shaft 31 is inserted therein.

A plurality of magnet holes 72 are arranged at substantially equal intervals in the circumferential direction. Each one of the plurality of permanent magnets 61 is embedded in each of the plurality of the magnet holes 72. That is, a permanent magnet portion 320 is formed in a magnet hole 72. In this case, the plurality of permanent magnets 61 include a permanent magnet 611 of which the magnetic pole of the radially outer surface is an N-pole and a permanent magnet 612 of which the magnetic pole of the radially outer surface is an S-pole. The permanent magnet 611 of which the magnetic pole of the radially outer surface is an N-pole and the permanent magnet 612 of which the magnetic pole of the radially outer surface is an S-pole are arranged alternately in the circumferential direction. Therefore, in the

permanent magnets

611 and 612 adjacent to each other in the circumferential direction, magnetic poles of the radially outer surfaces thereof are different from each other.

As shown in Fig. 5, non-magnetic holes 73 are respectively provided at positions adjacent to both sides of the magnet hole 72 in the circumferential direction. Therefore, the non-magnetic hole 73 has a configuration in which at least a part from an end portion on the radially outer side to a substantially central portion, in the side surface of each of the permanent magnet 61 in the circumferential direction, is adjacent to the same part in the other non-magnetic hole 73. The non-magnetic hole 73 suppresses leakage of the magnetic flux from both ends of the permanent magnet 61 in the circumferential direction. In the embodiment, each of the non-magnetic hole 73 is a cavity. However, a non-magnetic member such as resin may be inserted in the non-magnetic hole 73.

Furthermore, in the first rotor core 510, a part located on the more radially outward side than the magnet hole 72 and the non-magnetic hole 73 and a part located on the more radially inner side than the magnet hole 72 and the non-magnetic hole 73 are respectively connected to the same parts adjacent thereto by a radial-direction connection portion 74 positioned between two magnet holes 72 which are adjacent to each other in the circumferential direction. An outer side connection portion 741 positioned between the non-magnetic holes 73 adjacent to each other in the circumferential direction and an inner side connection portion 742 positioned between vicinities of the radially inner end portions of side surfaces of the adjacent permanent magnets 61 in the circumferential direction constitute the radial-direction connection portion 74.

An end portion of the outer side connection portion 741 on the radially outer side is joined to a central portion 621 of the flux barrier portion 62 described below. Both side surfaces of the outer side connection portion 741 in the circumferential direction are adjacent to the non-magnetic holes 73. In addition, a width of the outer side connection portion 741 in the circumferential direction is substantially constant.

An end portion of the inner side connection portion 742 on the radially outer side is joined to the end portion of the outer side connection portion 741 on the radial direction inner side. Both side surfaces of the inner side connection portion 742 in the circumferential direction are adjacent to both side surfaces of two adjacent permanent magnets 61 in the circumferential direction. End portions on the radially inner side of both end surfaces of the inner side connection portion 742 in the circumferential direction are adjacent to end portions on the radially inner side of the side surfaces of the permanent magnet 61 in the circumferential direction. In addition, end portions on the radially outer side of both end surfaces of the inner side connection portion 742 in the circumferential direction are adjacent to the non-magnetic holes 73.

According to the configuration described above, the first rotor core 510 has a plurality of flux barrier portions 62 and a plurality of effectual magnetic flux portions 63. The plurality of flux barrier portions 62 and the plurality of effectual magnetic flux portions 63 are arranged alternately in the circumferential direction on an outer circumferential surface of the first rotor core 510. Each of the flux barrier portions 62 is a magnetically saturated part between the magnetic poles of the permanent magnets 61 adjacent to each other in the circumferential direction. In the embodiment, a part of the first rotor core 510 which is magnetized with equal to or more than 70% of the saturation magnetization of the material constituting the first rotor core 510 when the motor 1 is stopped is designated as the flux barrier portion 62.

Each of the effectual magnetic flux portions 63 is a part constituting a part of a magnetic path between the permanent magnet 61 and the stator 23 positioned on the radially outer side of the rotor 32. The magnetic flux generated between the permanent magnet 61 and the stator 23 flows through the effectual magnetic flux portion 63.

The plurality of effectual magnetic flux portions 63 includes an N-pole magnetic flux portion 631 and an S-pole magnetic flux portion 632. A radially outer surface of the N-pole magnetic flux portion 631 is an N-pole. A radially outer surface of the S-pole magnetic flux portion 632 is an S-pole. The N-pole magnetic flux portion 631 is disposed on the radially outer side of the permanent magnet 611 of which a magnetic pole of the radially outer surface is an N-pole. In addition, The S-pole magnetic flux portion 632 is disposed on the radially outer side of the permanent magnet 612 of which a magnetic pole of the radially outer surface is an S-pole. That is, the plurality of N-pole magnetic flux portions 631 and the plurality of S-pole magnetic flux portions 632 are arranged alternately in the circumferential direction.

The first rotor unit 51 and the second rotor unit 52 have a substantially same configuration. The second rotor unit 52 has a second rotor core 520 and the plurality of permanent magnets 61, similar to the first rotor unit 51. Since the detailed description of each part of the second rotor unit 52 is the same as that of the first rotor unit 51, redundant description will be omitted.

As described above, the non-magnetic substance layer 50 is interposed between the first rotor unit 51 and the second rotor unit 52. The non-magnetic substance layer 50 is a plate-shaped member spread in the radial direction around the shaft 31. The non-magnetic substance layer 50 is made of resin material, for example. However, the non-magnetic substance layer 50 may be made of non-magnetic metal material such as stainless steel or copper as long as it is a non-magnetic substance.

The first rotor unit 51 and the second rotor unit 52 are arranged at a position where the permanent magnets 61 thereof are deviated from each other in the circumferential direction. Thereby, the flux barrier portion 62 of the first rotor unit 51 and the flux barrier portion 62 of the second rotor unit 52 are arranged so as to be deviated from each other in the circumferential direction, as shown in Fig. 3. Similarly, the effectual magnetic flux portion 63 of the first rotor unit 51 and the effectual magnetic flux portion 63 of the second rotor unit 52 are arranged so as to be deviated from each other in the circumferential direction. That is, the rotor 32 has a so-called step skew structure. Thereby, in the first rotor unit 51 and the second rotor unit 52, the changes in the magnetic flux distribution in each outer circumferential surface thereof are offset. Therefore, the changes in the magnetic flux distribution in an entire outer circumferential surface of the rotor 32 occur smoothly. As a result, cogging torque and torque ripple of the motor 1 are reduced.

In addition, since the first rotor unit 51 and the second rotor unit 52 are deviated from each other in the circumferential direction, the flux barrier portion 62 of the first rotor unit 51 overlaps a part of the effectual magnetic flux portion 63 of the second rotor unit 52 in the axial direction, as shown in Figs. 3 and 6. Similarly, the flux barrier portion 62 of the second rotor unit 52 overlaps a part of the effectual magnetic flux portion 63 of the first rotor unit 51.

Meanwhile, the non-magnetic substance layer 50 is interposed between the first rotor unit 51 and the second rotor unit 52, as described above. Thereby, short-circuiting of the magnetic flux is prevented from occurring between the flux barrier portion 62 of the first rotor unit 51 and the effectual magnetic flux portion 63 of the second rotor unit 52, and also, between the effectual magnetic flux portion 63 of the first rotor unit 51 and the flux barrier portion 62 of the second rotor unit 52. That is, reduction in the effectual magnetic flux of the rotor 32 is suppressed.

Furthermore, in the motor 1, a part of the flux barrier portion 62 of the first rotor unit 51 and a part of the flux barrier portion 62 of the second rotor unit 52 are arranged so as to overlap each other in the axial direction, as shown in Figs. 3 and 6.

Therefore, the N-pole magnetic flux portion 631 of the first rotor unit 51 and the S-pole magnetic flux portion 632 of the second rotor unit 52 do not overlap each other in the axial direction. Similarly, the S-pole magnetic flux portion 632 of the first rotor unit 51 and the N-pole magnetic flux portion 631 of the second rotor unit 52 do not overlap each other in the axial direction. As a result, short-circuiting of the magnetic flux is further prevented from occurring between the first rotor unit 51 and the second rotor unit 52. That is, reduction in the effectual magnetic flux of the rotor 32 is further suppressed. Thereby, reduction in torque of the motor 1 is suppressed.

<2-3. Shapes of Flux Barrier Portion and Effectual Magnetic Flux Portion>
Subsequently, shapes of the flux barrier portion 62 and the effectual magnetic flux portion 63 will be described.

As shown in Fig. 5, the flux barrier portion 62 is disposed between the N-pole magnetic flux portion 631 and the S-pole magnetic flux portion 632. The N-pole magnetic flux portion 631 is disposed on the radially outer side of the N-pole permanent magnet 611 of which a magnetic pole of a radially outer surface is an N-pole. The S-pole magnetic flux portion 632 is disposed on a radially outer side of the S-pole permanent magnet 612 of which a magnetic pole of a radially outer surface is an S-pole. In addition, the flux barrier portion 62 has a central portion 621, a circumferential direction connection portion 622 and an end wall portion 623. The central portion 621 is disposed substantially at the center of the flux barrier portion 62 in the circumferential direction. An end portion of the central portion 621 on a radially inner side is joined to an end portion of the outer side connection portion 741 on a radially outer side. The circumferential direction connection portions 622 are disposed on both sides of the flux barrier portion 62 in the circumferential direction and are joined to the central portion 621 and the end wall portion 623. An end surface of the circumferential direction connection portion 622 on a radially inner side is adjacent to the non-magnetic hole 73.

In the embodiment, shapes of radial outer surfaces of the central portion 621 and the circumferential direction connection portion 622 are a straight line or an arc centering on the central axis 9, in cross-sectional surfaces thereof perpendicular to the central axis 9.

The end wall portions 623 are disposed on both ends of the flux barrier portion 62 in the circumferential direction. In the embodiment, each of the end wall portions 623 overlaps a part of the radially outer surface of the permanent magnet 61 in the radial direction. In addition, the radially outer surface of the end wall portion 623 is substantially parallel to the radially outer surface of the permanent magnet 61. Furthermore, a radial width between the radially outer surface of the permanent magnet 61 and the radially outer surface of the effectual magnetic flux portion 63 is greater than a radial width between the radially outer surface of the permanent magnet 61 and the radially outer surface of the end wall portion 623.

In this case, the radial width between the radially outer surface of the permanent magnet 61 and the radially outer surface of the effectual magnetic flux portion 63 is a radial width at a position where the radial width is maximum between the radially outer surface of the permanent magnet 61 and the radially outer surface of the effectual magnetic flux portion 63. In addition, the radial width between the radially outer surface of the permanent magnet 61 and the radially outer surface of the end wall portion 623 is a radial width at a position where the radial width is maximum between the radially outer surface of the permanent magnet 61 and the radially outer surface of the end wall portion 623.

Thereby, it is easy for the end wall portion 623 to be magnetically saturated. That is, density of the magnetic flux of the end wall portion 623 is comparatively greater than that of the effectual magnetic flux portion 63. Therefore, in both end portions of the effectual magnetic flux portion 63 in the circumferential direction, it is difficult for a magnetic path to be directed toward the flux barrier portion 62, and it is easy for the magnetic path to be directed toward the radial direction.

Furthermore, the flux barrier portion 62 is magnetically saturated between the permanent magnet 611 and the permanent magnet 612. That is, the flux barrier portion 62 is magnetically saturated between a part where a part of the magnetic pole surface of the permanent magnet 611 on the radially outer side overlaps one end wall portion 623 in the radial direction and a part where a part of the magnetic pole surface of the permanent magnet 612 on the radially outer side overlaps the other end wall portion 623 in the radial direction.

In this case, the non-magnetic hole 73 is located on a radially inner side of the circumferential direction connection potion 622. A radial width between the radially outer surface of the non-magnetic hole 73 and the radially outer surface of the circumferential direction connection portion 622 are substantially constant. The radial width between the radially outer surface of the non-magnetic hole 73 and the radially outer surface of the circumferential direction connection portion 622 is substantially the same as the radial width between the radially outer surface of the permanent magnet 61 and the radially outer surface of the end wall portion 623. That is, the magnetic path between the permanent magnet 611 and the permanent magnet 612 is prevented from spreading in the radial direction, by the non-magnetic hole 73. Thereby, upon comparison with the end wall portion 623, the density of the magnetic flux is prevented from being reduced in the central portion 621 and the circumferential direction connection portion 622.

Furthermore, in the embodiment, a circumferential width of the radially outer surface of each permanent magnet 61 is greater than that of each effectual magnetic flux portion 63. Thereby, it is possible to further increase the torque of the motor 1, compared to a case where the circumferential width of the radially outer surface of each permanent magnet 61 is smaller than that of each effectual magnetic flux portion 63. In other words, by making the end wall portion 623 magnetically saturated using each permanent magnet 61, efficiency of the magnetic flux flowing from each permanent magnet 61 to each effectual magnetic flux portion 63 is improved. In addition, by making the end wall portion 623 magnetically saturated using each permanent magnet 61, it is possible to enhance rotational efficiency of the motor 1.

Furthermore, in the embodiment, the radially outer surface of the effectual magnetic flux portion 63 protrudes further in the radially outer direction than the radially outer surface of the flux barrier portion 62. Thereby, in outer surfaces of the first rotor core 510 and the second rotor core 520, density of the magnetic flux thereof in the circumferential direction approximately shows not the rectangular waveform but the sine waveform. That is, a waveform of the induced voltage generated in the motor 1 approximately has the sine waveform. In addition, in the embodiment, a shape of radially outer surfaces of the effectual magnetic flux portion 63 is an arc centering on a point on the further radially outer direction than the central axis 9, in cross-sectional surfaces thereof perpendicular to the central axis 9. Therefore, a waveform of the induced voltage generated in the motor 1 approximately has the sine waveform.

In the meantime, the first rotor core 510 has a line-symmetric shape seen from the axial direction, as shown in Fig. 4. Similarly, the second rotor core 520 has a line-symmetric shape seen from the axial direction, as well. Therefore, the center of each effectual magnetic flux portion 63 in the circumferential direction overlaps the center of each permanent magnet 61 in the circumferential direction in the radial direction. Thereby, it is possible to obtain the induced voltage having the same waveform regardless of the rotation direction of the rotor 32.

<3. Modification Example>
Hereinbefore, the exemplary embodiments of the present invention are described. However, the present invention is not limited to the embodiments described above.

Fig. 7 is a perspective view of a rotor 32B according to a modification example. In the example shown in Fig. 7, a cavity layer 50B are interposed between a first rotor unit 51B and a second rotor unit 52B adjacent to each other in the axial direction. Also, the cavity layer 50B constitutes a non-magnetic substance layer. The cavity layer 50B is formed by interposing an annular-shaped non-magnetic substance ring between the first rotor unit 51B and the second rotor unit 52B, for example. In the example shown in Fig. 7, short-circuiting of the magnetic flux is prevented from occurring between the flux barrier portion 62B of the first rotor unit 51B and the effectual magnetic flux portion 63B of the second rotor unit 52B overlapping the flux barrier portion 62B in the axial direction, as well. Similarly, short-circuiting of the magnetic flux is prevented from occurring between the effectual magnetic flux portion 63B of the first rotor unit 51B and the flux barrier portion 62B of the second rotor unit 52B overlapping the effectual magnetic flux portion 63B in the axial direction.

Fig. 8 is a perspective view of a rotor 32C according to another modification example. In the example shown in Fig. 8, the rotor 32C has a first rotor unit 51C, a second rotor unit 52C, a third rotor unit 53C and two non-magnetic substance layers 50C. The first rotor unit 51C and the second rotor unit 52C are adjacent to each other in the axial direction with the non-magnetic substance layer 50C interposed therebetween. The second rotor unit 52C and the third rotor unit 53C are adjacent to each other in the axial direction with the non-magnetic substance layer 50C interposed therebetween. That is, the two non-magnetic substance layers 50C are respectively interposed between the first rotor unit 51C and the second rotor unit 52C, and between the second rotor unit 52C and the third rotor unit 53C.

In the example shown in Fig. 8, a part of a flux barrier portion 62C of the first rotor unit 51C and a part of a flux barrier portion 62C of the second rotor unit 51C overlap each other in the axial direction. In addition, a part of the flux barrier portion 62C of the second rotor unit 52C and a part of a flux barrier portion 62C of the third rotor unit 53C overlap each other in the axial direction. That is, in two rotor units adjacent to each other in the axial direction, a part of the flux barrier portion 62C of one rotor unit and a part of the flux barrier portion 62C of the other rotor unit overlap each other in the axial direction. Therefore, short-circuiting of the magnetic flux is also prevented from occurring between the adjacent rotor units, in the example shown in Fig. 8. That is, reduction in the effectual magnetic flux of the rotor units 51C to 53C is suppressed. As in the example shown in Fig. 8, the number of the rotor unit may be equal to or more than three or four as long as it is equal to or more than two.

Fig. 9 is a top view of a first rotor unit 51D according to another modification example. In the embodiments described above, the rotor core has a line-symmetric shape seen from the axial direction. In the example shown in Fig. 9, the first rotor unit 51D does not have a line-symmetric shape seen from the axial direction. Specifically, a radially outer surface of an effectual magnetic flux portion 63D has a shape biased in the circumferential direction. In the case where the rotor rotates in only one direction, if the rotor has a rotational symmetric shape seen from the axial direction even though it does not have a line-symmetric shape seen from the axial direction, it is also possible to obtain the induced voltage having a stable waveform in the example shown in Fig. 9.

Fig. 10 is a top view of a first rotor unit 51E according to another modification example. In the example shown in Fig. 10, an entire radially outer surface of a permanent magnet 61E overlaps an effectual magnetic flux portion 63E in the radial direction. Therefore, the radially outer surface of the permanent magnet 61E and a flux barrier portion 62E do not overlap each other in the radial direction. If a part of the flux barrier portion 62E of the first rotor unit 51E and a part of a flux barrier portion 62E of a second rotor unit 52E overlap each other in the axial direction, short-circuiting of magnetic flux is also prevented between the adjacent rotor cores in the example shown in Fig. 10. That is, reduction in the effectual magnetic flux of the rotor core is suppressed.

Fig. 11 is a perspective view of a rotor 32F according to another modification example. In the rotors according to embodiments described above, each of the plurality of permanent magnet portions is constituted by a single piece of permanent magnet. However, the present invention is not limited thereto. A permanent magnet portion corresponding to an effectual magnetic flux portion may be constituted by two or more pieces of permanent magnet. For example, in each of a first rotor unit 51F and a second rotor unit 52F, a permanent magnet portion 320F corresponding to an effectual magnetic flux portion 63F is constituted by a first piece 81F and a second piece 82F, in the example shown in Fig. 11. The first piece 81F and the second piece 82F constituting each permanent magnet portion 320F are permanent magnets of which radially outer surfaces have the same magnetic pole. In the example shown in Fig. 11, the first piece 81F and the second piece 82F are arranged in a V-shape widening on the radially outer side. Thereby, the permanent magnet portion 320F forms a single magnetic pole toward the radially outer side.

Furthermore, in the embodiment described above, the non-magnetic substance layer is a plate-shaped member. However, the present invention is not limited thereto. It is also possible to simultaneously perform fixing of the rotor core and forming of the non-magnetic substance layer by an integral molding method of pouring molten resin into a mold in which two or more rotor cores are inserted.

In addition, it is also possible to configure a generator in the same structure as the motor according to embodiments or modification examples described above. The electrical rotating machine of the present invention may be a generator used in a vehicle, an electrically-assisted bicycle, a wind power generator or the like.

Still further, the detailed shape of each member may be different from the shape shown in the drawings of the present application. In addition, the elements exemplified in the embodiments or the modification examples described above may be appropriately combined together to an extent where there is no contradiction.

It is possible to apply the present invention to an electrical rotating machine.

1: motor
2: static section
3: rotation section
9, 9A: central axis
21: housing
22: lid portion
23: stator
31: shaft
32, 32A, 32B, 32C, 32D, 32F: rotor
50, 50A, 50C: non-magnetic substance layer
50B: cavity layer
51, 51B, 51C, 51D, 51E, 51F: first rotor unit
52, 52B, 52C, 52E, 52F: second rotor unit
53C: third rotor unit
61, 61A, 61E: permanent magnet
62, 62A, 62B, 62C, 62E: flux barrier portion
63, 63A, 63B, 63D, 63E, 63F: effectual magnetic flux portion
71: shaft hole
72: magnet hole
73: non-magnetic hole
81F: first piece
82F: second piece
320. 320A. 320F: permanent magnet portion
510, 510A: first rotor core
520, 520A: second rotor core
611, 611A: permanent magnet
612, 612A: permanent magnet
621: central portion
622: circumferential direction connection portion
623: end wall portion
631, 631A: N-pole magnetic flux portion
632, 632A: S-pole magnetic flux portion

Claims

An electrical rotating machine comprising:
a rotor which rotates about a central axis and has a substantially cylindrical shape,
wherein the rotor includes
a first rotor core,
a second rotor core which overlaps the first rotor core in an axial direction,
a non-magnetic substance layer which is interposed between the first rotor core and the second rotor core, and
a plurality of permanent magnet portions which are embedded in the first rotor core and the second rotor core,
wherein the plurality of permanent magnet portions are arranged at substantially equal intervals in a circumferential direction, in each of the first rotor core and the second rotor core,
wherein, in two permanent magnet portions adjacent to each other in the circumferential direction, magnetic poles of radially outer surfaces thereof are different from each other,
wherein each of the first rotor core and the second rotor core has a stage skew structure in which the plurality of the permanent magnet portions thereof are arranged so as to be deviated from each other in the circumferential direction,
wherein each of the first rotor core and the second rotor core includes
a plurality of flux barrier portions which are magnetically saturated between the magnetic poles of the permanent magnet portions adjacent to each other in the circumferential direction, and
a plurality of effectual magnetic flux portions which are disposed on a radially outer side of the permanent magnet portions and function as a magnetic path between the permanent magnet portions and an outside of the rotor,
wherein the plurality of the flux barrier portions and the plurality of the effectual magnetic flux portions are arranged alternately in the circumferential direction on an outer circumferential surface of each of the first rotor core and the second rotor core, and
wherein the flux barrier portion of the first rotor core overlaps both of a part of the flux barrier portion of the second rotor core and a part of the effectual magnetic flux portion of the second rotor core, in the axial direction.
The electrical rotating machine according to Claim 1,
wherein each of the plurality of the permanent magnet portions is constituted by a single piece.
The electrical rotating machine according to Claim 1,
wherein each of the plurality of the permanent magnet portions is constituted by a plurality of pieces.
The electrical rotating machine according to any one of Claims 1 to 3,
wherein the flux barrier portion is magnetized with more than 70% of the saturation magnetization of a material constituting the rotor core.
The electrical rotating machine according to any one of Claims 1 to 4,
wherein the non-magnetic substance layer is made of resin.
The electrical rotating machine according to any one of Claims 1 to 5,
wherein the flux barrier portion has an end wall portion which overlaps a part of the two permanent magnet portions, which are adjacent to each other in the circumferential direction, in a radial direction.
The electrical rotating machine according to Claim 6,
wherein a radial width between a radially outer surface of the permanent magnet portion and a radially outer surface of the effectual magnetic flux portion is greater than a radial width between the radially outer surface of the permanent magnet portion and a radially outer surface of the end wall portion.
The electrical rotating machine according to Claim 7,
wherein the radial width between the radially outer surface of the permanent magnet portion and the radially outer surface of the effectual magnetic flux portion is a radial width at a position where the radial width is maximum between the radially outer surface of the permanent magnet portion and the radially outer surface of the effectual magnetic flux portion, and
wherein the radial width between the radially outer surface of the permanent magnet portion and the radially outer surface of the end wall portion is a radial width at a position where the radial width is maximum between the radially outer surface of the permanent magnet portion and the radially outer surface of the end wall portion.
The electrical rotating machine according to Claim 7 or 8,
wherein the radially outer surface of the end wall portion is substantially parallel to the radially outer surface of the permanent magnet portion.
The electrical rotating machine according to any one of Claims 1 to 9, further comprising,
an armature disposed radially outside the rotor,
wherein the radially outer surface of the effectual magnetic flux portion protrudes further in the radial direction than the radially outer surface of the flux barrier portion.
The electrical rotating machine according to Claim 10,
wherein a shape of the radially outer surface of the effectual magnetic flux portion is an arc centering on a point on a radially outer side than the central axis, in a cross-sectional surface perpendicular to the central axis.
The electrical rotating machine according to any one of Claims 1 to 11,
wherein a center of the effectual magnetic flux portion in the circumferential direction and a center of the permanent magnet portion in the circumferential direction overlap each other in the radial direction.