JP2021048682A - Rotor - Google Patents

Abstract

To provide a rotor of a rotary electric machine capable of suppressing generation of eddy current while preventing breakage of a permanent magnet.SOLUTION: A permanent magnet M has a plurality of slits S1 to S3 that are formed in a rectangular cross-sectional shape and extends from a first long side toward a second long side SA2 at intervals in a longitudinal direction of the first long side SA1. In the permanent magnet, the first long side and the second long side are inclined at an angle of less than 90° with respect to a d-axis so that the first long side faces the d-axis, the second long side faces a q-axis, and a first short side SS1 faces an outer peripheral surface of the rotor iron core, and the first short side is in contact with a holding projection 34d. At least one slit close to the first short side extends to the vicinity of an abutment virtual line from the first long side without exceeding the abutment virtual line C3 that passes an abutment position P1 where the holding projection and the first short side come into contact and extends in parallel to the first long side. At least one slit close to the second short side SS2 extends from the first long side to the vicinity of the second long side beyond the abutment virtual line.SELECTED DRAWING: Figure 5

Description

An embodiment of the present invention relates to a rotor of a rotating electric machine provided with a permanent magnet.

In recent years, due to remarkable research and development of permanent magnets, permanent magnets having a high magnetic energy product have been developed, and permanent magnet type rotary electric machines using such permanent magnets are being applied as electric motors or generators for trains and automobiles. Usually, a permanent magnet type rotary electric machine includes a cylindrical stator and a cylindrical rotor rotatably supported inside the stator. The rotor includes a rotor core and a plurality of permanent magnets embedded in the rotor core.
In such a permanent magnet type rotary electric machine, an eddy current is generated in the permanent magnet due to a change in the magnetic flux interlinking with the permanent magnet, which contributes to an increase in loss and irreversible demagnetization due to an increase in magnet temperature. ing. As a method of reducing the eddy current loss, a method of providing a slit in the permanent magnet has been proposed, but damage to the permanent magnet due to a decrease in strength has become a problem.

Japanese Unexamined Patent Publication No. 2000-295804

An object of the embodiment of the present invention is to provide a rotor of a rotating electric machine capable of suppressing the generation of an eddy current while preventing damage to a permanent magnet.

According to the embodiment, the rotor of the rotary electric machine includes a plurality of magnetic poles arranged in the circumferential direction around the central axis, a magnet embedding hole provided in each of the magnetic poles, and a holding protrusion protruding into the magnet embedding hole. It is formed in a rectangular cross-sectional shape having a rotor core having a magnet, a first long side and a second long side facing each other, and a first short side and a second short side facing each other, and the length of the first long side. A permanent magnet having a plurality of slits extending from the first long side to the second long side at intervals in the direction, arranged in the magnet embedding hole, and in contact with the holding protrusion is provided. ing. In the cross section of the rotor core orthogonal to the central axis, the axial end of the magnetic pole and the axis extending in the radial direction through the central axis are defined as the q-axis, and the axis is electrically connected to the q-axis in the circumferential direction. Assuming that the axes separated by 90 degrees are the d-axis, the permanent magnet has the first long side facing the d-axis side and the second long side facing the q-axis side. The first long side and the second long side are arranged so as to face the outer peripheral surface of the rotor core so as to be inclined at an angle smaller than 90 degrees with respect to the d-axis, and the first short side is said. Placed in contact with the holding protrusion,
Assuming that a straight line extending parallel to the first long side through the contact position where the holding protrusion and the first short side are in contact is a contact virtual line, at least one of the plurality of slits close to the first short side. One slit extends from the first long side to the vicinity of the contact virtual line without crossing the contact virtual line, and at least one slit near the second short side is the first length. It extends from the side beyond the contact virtual line to the vicinity of the second long side.

FIG. 1 is a cross-sectional view of a permanent magnet type rotary electric machine according to an embodiment. FIG. 2 is an enlarged cross-sectional view showing a part of the rotor of the rotary electric machine. FIG. 3 is a perspective view showing a rotor core and some permanent magnets of the rotary electric machine. FIG. 4 is a perspective view schematically showing a permanent magnet. FIG. 5 is a cross-sectional view of the permanent magnet schematically showing the force acting on the permanent magnet. FIG. 6 is a cross-sectional view showing a part of the rotor according to the first modification. FIG. 7 is a cross-sectional view showing a part of the rotor according to the second modification.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same reference numerals are given to common configurations throughout the embodiment, and duplicate description will be omitted. In addition, each figure is a schematic view for facilitating the understanding of the embodiment, and the shape, dimensions, ratio, etc. of the embodiment are different from those of the actual device, but these are based on the following explanation and known techniques. The design can be changed as appropriate.

FIG. 1 is a cross-sectional view of a permanent magnet type rotary electric machine according to an embodiment, and FIG. 2 is an enlarged cross-sectional view of one magnetic pole portion of the rotor.
As shown in FIG. 1, the rotary electric machine 10 is configured as, for example, an inner rotor type rotary electric machine, and has an annular or cylindrical stator 12 supported by a fixing frame (not shown) and a central axis C inside the stator. It is provided with a rotor 14 that is rotatable around the stator and is supported coaxially with the stator 12. The rotary electric machine 10 is suitably applied to a drive motor or a generator in, for example, a hybrid electric vehicle (HEV) or an electric vehicle (EV).

The stator 12 includes a cylindrical stator core 16 and an armature winding 18 wound around the stator core 16. The stator core 16 is formed by laminating a large number of magnetic materials, for example, a large number of annular electromagnetic steel plates such as silicon steel, in a concentric manner. A plurality of slots 20 are formed in the inner peripheral portion of the stator core 16. The plurality of slots 20 are arranged at equal intervals in the circumferential direction. Each slot 20 opens on the inner peripheral surface of the stator core 16 and extends in the radial direction from the inner peripheral surface. Further, each slot 20 extends over the entire length of the stator core 16 in the axial direction. By forming the plurality of slots 20, the inner peripheral portion of the stator core 16 constitutes a plurality of (for example, 48 in the present embodiment) stator teeth 21 facing the rotor 14. Armature windings 18 are embedded in the plurality of slots 20 and wound around the stator teeth 21. By passing an electric current through the armature winding 18, a predetermined interlinkage magnetic flux is formed in the stator 12 (stator teeth 21).

The rotor 14 includes a cylindrical shaft (rotating shaft) 22 whose ends are rotatably supported by bearings (not shown), a cylindrical rotor core 24 fixed at substantially the center of the shaft 22 in the axial direction, and the like. It has a plurality of permanent magnets M embedded in the rotor core 24. The rotor 14 is coaxially arranged with a slight gap (air gap) inside the stator 12. That is, the outer peripheral surface of the rotor 14 faces the inner peripheral surface of the stator 12 with a slight gap. The rotor core 24 has an inner hole 25 formed coaxially with the central axis C. The shaft 22 is inserted and fitted into the inner hole 25 and extends coaxially with the rotor core 24. The rotor core 24 is configured as a laminated body in which a large number of magnetic materials, for example, a large number of annular electromagnetic steel plates 24a (see FIG. 3) such as silicon steel are laminated concentrically.

In this embodiment, the rotor 14 is set to a plurality of magnetic poles, for example, 8 magnetic poles. In the rotor core 24, the axes extending in the radial direction of the rotor core 24 passing between the central axis C and the magnetic poles adjacent to each other in the circumferential direction are electrically separated by 90 ° in the circumferential direction with respect to the q-axis and the q-axis. The axis is referred to as the d-axis. The d-axis and the q-axis are provided alternately in the circumferential direction of the rotor core 24 and in a predetermined phase. One magnetic pole portion of the rotor core 24 means a region between the q-axis (a circumferential angle region of 1/8 circumference). The center of one magnetic pole in the circumferential direction is the d-axis.

Two permanent magnets M are arranged on the rotor core 24 for each magnetic pole. Magnet embedding holes (hereinafter referred to as embedding holes) 34 are formed on both sides of each d-axis in the circumferential direction of the rotor core 24. The two permanent magnets M are loaded and arranged in the embedding holes 34, respectively, and are fixed to the rotor core 24 by, for example, an adhesive or the like.
According to this embodiment, a plurality of void holes (cavities) 30 are formed in the rotor core 24. The gap holes 30 extend axially through the rotor core 24, respectively. The gap holes 30 are located on the d-axis in the vicinity of the outer peripheral surface of the rotor core 24, and are provided between the two embedding holes 34.

As shown in FIG. 2, the embedding hole 34 functioning as a flux barrier extends axially through the rotor core 24. When viewed in a cross section orthogonal to the central axis C of the rotor core 24, each embedded hole 34 has a rectangular magnet loading area 34a corresponding to the cross-sectional shape of the permanent magnet M and both ends in the longitudinal direction of the magnet loading area 34a. It has an inner peripheral side gap 34b and an outer peripheral side gap 34c extending from the outer peripheral side gap 34b. Each of the embedding holes 34 is inclined at an angle smaller than 90 ° with respect to the d-axis. The two embedding holes 34 are arranged side by side in a substantially V shape, for example, on both sides in the circumferential direction of the d-axis. That is, the inner peripheral side gaps 34b of the two embedding holes 34 are adjacent to each other on the d-axis and face each other with a slight gap. The outer peripheral side gaps 34c of the two embedding holes 34 are located near the outer peripheral surface of the rotor core 24, are separated from the inner peripheral side gaps 34b in the circumferential direction from the d-axis, and are respectively separated from the inner peripheral side gaps 34b. It is located on the outer peripheral surface side of the rotor core 24. As described above, the two embedding holes 34 are arranged so as to be inclined so that the distance from the d-axis gradually increases from the inner peripheral side end to the outer peripheral side end.

The rectangular magnet loading region 34a is formed between a linear first side edge 35a and a linear second side edge 35b that faces the first side edge 35a in parallel with a gap. The first side edge 35a and the second side edge 35b extend at an angle smaller than 90 ° with respect to the d-axis, respectively, and the first side edge 35a extends on the d-axis side with respect to the second side edge 35b. And it is located on the outer peripheral surface side.
The inner peripheral side gap 34b extends from the end of the magnet loading region 34a on the d-axis side toward the d-axis. The outer peripheral side gap 34c extends from the outer peripheral surface side end of the magnet loading region 34a toward the outer peripheral surface of the rotor core 24. The inner peripheral side gap 34b and the outer peripheral side gap 34c function as magnetic gaps (flux barriers) that suppress magnetic flux leakage from both ends in the longitudinal direction of the permanent magnet M to the rotor core 24, and reduce the weight of the rotor core 24. Also contributes to.

In the rotor core 24, a narrow magnetic path narrowing portion (first bridge portion) 36 is formed between the inner peripheral side gaps 34b of the two magnet embedding holes 34. A narrow magnetic path narrowing portion (second bridge portion) 38 is formed between the outer peripheral side gap 34c of each embedding hole 34 and the outer peripheral edge of the rotor core 24. Further, the rotor core 24 has a pair of holding protrusions 34d provided at both ends in the longitudinal direction of the second side edge 35b of the magnet loading region 34a and protruding into the embedding holes 34, respectively.

FIG. 3 is a perspective view showing the rotor core and a part of the permanent magnets, and FIG. 4 is a perspective view schematically showing the permanent magnets.
As shown in FIG. 3, the permanent magnet M is formed in an elongated flat plate shape, for example, and has a length L1 substantially equal to the axial length of the rotor core 24. Each permanent magnet M is embedded over substantially the entire length of the rotor core 24 in the axial direction. The permanent magnet M may be configured by combining magnets divided into a plurality of magnets in the axial direction (longitudinal direction). In this case, the total length of the plurality of magnets is substantially equal to the axial length of the rotor core 24. Is formed to be.
As shown in FIG. 4, the cross section of the permanent magnet M has a first long side (front surface) SA1 and a second long side (back surface) SA2 facing each other in parallel, and a first short side SS1 and a first short side facing each other. It is formed in a rectangular shape having two short sides SS2.

According to this embodiment, a plurality of slits S1, S2, and S3 are provided on the first long side SA1 of the permanent magnet M, for example, three slits S1, S2, and S3. The three slits S1, S2, and S3 are each formed over the entire length of the permanent magnet M in the longitudinal direction. The three slits S1, S2, and S3 are provided at equal intervals in the width direction of the permanent magnet M (longitudinal direction of the first long side SA1). Each slit extends from the first long side SA1 toward the second long side SA2 and is formed substantially perpendicular to the first long side SA1. The depth of the slit, that is, the length from the first long side SA1 to the tip of the slit (extending end), is such that the slit S3 is formed shorter than the two slits S1 and S2.

As shown in FIG. 2, the permanent magnet M is loaded in the magnet loading region 34a of the embedding hole 34, and the first long side SA1 abuts on or faces the first side edge 35a with a slight gap. , The second long side SA2 is in contact with the second side edge 35b, or is opposed to each other with a slight gap. The first short side SS1 and the second short side SS2 of the permanent magnet M are in contact with the holding projection 34d, respectively. As a result, the permanent magnet M is arranged so that the first long side SA1 and the second long side SA2 are inclined at an angle smaller than 90 degrees with respect to the d axis, and the first long side SA1 faces the d axis side. The second long side SA2 faces the q-axis side. That is, the first long side SA1 is located on the outer peripheral side and the d-axis side of the rotor core 24 with respect to the second long side SA2. The first short side SS1 is located on the outer peripheral side of the rotor core 24 with respect to the second short side SS2.
The pair of holding protrusions 34d described above are provided on both ends of the second long side SA2 in the longitudinal direction and are in contact with the first short side SS1 and the second short side SS2 of the permanent magnet M, respectively. The permanent magnet M is held in the magnet loading region 34a in a state where the position in the longitudinal direction and the position in the width direction are positioned by the first side edge 35a, the second side edge 35b, and the pair of holding protrusions 34d. The two permanent magnets M located on both sides in the circumferential direction of the d-axis are arranged side by side in a substantially V shape. That is, the two permanent magnets M are arranged so as to be inclined so that the distance from the d-axis gradually increases from the inner peripheral side end to the outer peripheral side end. The permanent magnet M may be fixed to the rotor core 24 with an adhesive or the like.

Each permanent magnet M is magnetized in a direction perpendicular to the first long side SA1 and the second long side SA2. The two permanent magnets M located on both sides of each d-axis, that is, the two permanent magnets M constituting one magnetic pole are arranged so that the magnetization directions are the same. Further, the two permanent magnets M located on both sides of each q-axis are arranged so that the magnetization directions are opposite to each other. In the present embodiment, the rotary electric machine 10 has 8-pole (4-pole pair), 48 slots in which the front and back sides of the north and south poles of the permanent magnets M are alternately arranged for each adjacent magnetic pole, and is a single-layer distributed winding. It constitutes a wound permanent magnet embedded type rotary electric machine.

Next, the structure of the slit of the permanent magnet M will be described in more detail. FIG. 5 is a cross-sectional view of the permanent magnet schematically showing the force acting on the permanent magnet M.
As shown in FIG. 5, the contact position where the magnet center axis C2, the first short side SS1 and the holding protrusion 34d of the magnet cross section abut on a straight line extending in the longitudinal direction of the permanent magnet M through the cross-sectional center of gravity g of the permanent magnet M. When the straight line extending parallel to the first long side SA1 through P1 is the contact virtual line C3, the three slits S1, S2, and S3 are from the first long side SA1 located on the outer peripheral side of the magnet center axis C2. It extends substantially perpendicular to the first long side SA1 toward the second long side SA2 on the inner peripheral side. The three slits S1, S2, and S3 are provided at intervals in the longitudinal direction of the first long side SA1, for example, at equal intervals. In the direction of the magnet center axis C2, the slit S2 is provided substantially in the center of the permanent magnet M, and the slit S1 is provided between the slit S2 and the second short side SS2 on the inner peripheral side (d-axis side). .. The slit S3 is provided between the slit S2 and the first short side SS1 on the outer peripheral side (the outer peripheral surface side of the rotor core 24). The slits S1 and S2 extend deeply from the first long side SA1 beyond the contact virtual line C3 to the vicinity of the second long side SA2.

On the other hand, the slit S3 located on the outermost peripheral side, that is, the slit S3 closest to the first short side SS1 on the outer peripheral side and the holding projection 34d is formed shorter (shallow) than the slits S1 and S2. .. Specifically, the slit S3 extends from the first long side SA1 to the vicinity of the contact virtual line C3 without crossing the contact virtual line C3. The slit S3 is located in the region between the first long side SA1 and the contact virtual line C3, and extends from the first long side SA1 to the vicinity of the contact virtual line C3.
In the direction perpendicular to the first long side SA1, the length from the first long side SA1 to the tip (extending end) of the slit S3 is the contact between the first short side SS1 of the permanent magnet M and the holding protrusion 34d. Contact position (the position on the side of the first long side SA1 or the position farthest from the second long side SA2) P1 height (the first long side SA1 and the contact virtual line C3) It is formed shorter (lower) than the interval Ly). In the present embodiment, the protrusion height of the holding protrusion 34d is formed lower than the magnet center axis C2 of the permanent magnet M, and the state-of-the-art contact position P1 is between the magnet center axis C2 and the second long side SA2. positioned. That is, the contact virtual line C3 is located between the magnet central axis C2 and the second long side SA2. As described above, among the plurality of slits provided in the permanent magnet M, at least one slit S3 adjacent to the holding projection 34d on the outer peripheral side is formed shorter than the height of the most advanced contact position P1.
The slits S1 and S2 are formed longer than the interval Ly, extend beyond the contact virtual line C3 to the second long side SA2 side.
In the present embodiment, the distance between the extending end of the slit and the first long side SA1 in the direction perpendicular to the first long side SA1 is defined as the length of the slit.

As shown in FIG. 5, while the rotor 14 is rotating, the centrifugal force F acts on the permanent magnet M, and the component force FX in the direction of the magnet center axis C2 and the component force FY orthogonal to the magnet center axis C2 are permanent. It acts on the cross-sectional center of gravity g of the magnet M. At the same time, since the permanent magnet M is pressed against the holding protrusion 34d on the outer peripheral side by the component force FX, the reaction force RF from the holding protrusion 34d acts on the permanent magnet M. At this time, the slit S3 closest to the holding protrusion 34d on the outer peripheral side is formed shorter than the most advanced contact position P1, that is, is located on the first long side SA1 side of the contact virtual line C3. Therefore, the reaction force FR does not act directly on the slit S3. Therefore, even when the permanent magnet M is provided with a slit, cracking and damage of the permanent magnet due to the centrifugal force F and the reaction force RF are suppressed.

According to the rotary electric machine 10 according to the present embodiment configured as described above, eddy currents are generated in the permanent magnets M by providing a plurality of slits S1 to S3 in the permanent magnets M embedded in the rotor core 24. Can be effectively suppressed, and the eddy current loss can be significantly reduced. At the same time, it is possible to prevent the magnet from cracking or breaking due to the strong pressure generated at the contact portion between the permanent magnet M and the holding protrusion 34d due to the centrifugal force.
As a result, a rotor of a permanent magnet type rotating electric machine capable of suppressing the generation of eddy current while preventing damage to the permanent magnet can be obtained.

Next, a plurality of modifications of the rotor will be described. In the modification described below, the same parts as those in the above-described embodiment are designated by the same reference numerals, and detailed description thereof will be omitted or simplified.
(First modification)
FIG. 6 is a cross-sectional view of the rotor showing a part of the rotor according to the first modification in an enlarged manner.
As shown in the figure, according to the first modification, the permanent magnet M has three or more slits, for example, five slits S1, S2, S3, S4, S5. The slits S1 to S5 extend from the first long side SA1 of the permanent magnet M toward the second long side SA2, respectively. The slits S1 to S5 are provided at intervals in the longitudinal direction of the first long side SA1. In the first modification, each slit extends at an angle smaller than 90 ° with respect to the first long side SA1.

The length (depth) of the slit S3 located at the center of the first long side SA1 in the longitudinal direction, and the slit S1 located between the slit S3 and the second short side SS2 on the d-axis side of the permanent magnet M. The length of S2 is formed longer (deeper) than the distance Ly between the contact virtual line C3 and the first long side SA1, respectively. That is, the slits S1, S2, and S3 each extend from the first long side SA1 beyond the contact virtual line C3 to the vicinity of the second long side SA2.
Further, the lengths of the slits S4 and S5 located between the slit S3 and the first short side SS1 on the outer peripheral surface side of the permanent magnet M are formed to be shorter (shallow) than the interval Ly, respectively. That is, the two slits S4 and S5 adjacent to the first short side SS1 are formed to be shorter than the other slits S1 to S3 and shorter than the interval Ly. The slits S4 and S5 extend from the first long side SA1 to the vicinity of the contact virtual line C3 without exceeding the contact virtual line C3.
When the slit is inclined at an angle smaller than 90 ° with respect to the first long side SA1 of the permanent magnet M as in the first modification, the length component of the slit in the direction perpendicular to the first long side SA1 ( Ly) is defined as the length of the slit. That is, the shortest distance between the tip of the slit and the first long side SA1 is defined as the length of the slit.
In the first modification, all the slits S1 to S5 are inclined, but the present invention is not limited to this, and one or a plurality of slits extend perpendicularly to the first long side SA1. It may be configured.
The rotor according to the first modification configured as described above also has the same effect as that of the above-described embodiment.

(Second modification)
FIG. 7 is a cross-sectional view of the rotor showing a part of the rotor according to the second modification in an enlarged manner.
The holding protrusion 34d of the rotor core 24 is not limited to the holding protrusion protruding into the embedding hole 34 from the second side edge 35b of the embedding hole 34. As shown in FIG. 7, according to the second modification, the holding projection 34d of the rotor core 24 projects from the outer peripheral side end of the magnet embedding hole 34 into the outer peripheral side gap 34c, and the first short side SS1 of the permanent magnet M Is in contact with. Even in this case, the lengths (depths) of the slits S1 to S3 may be formed in the same manner as in the above-described embodiment.

It should be noted that the present invention is not limited to the above-described embodiments and modifications as they are, and at the implementation stage, the components can be modified and embodied within a range that does not deviate from the gist thereof. In addition, various inventions can be formed by an appropriate combination of the plurality of components disclosed in the above-described embodiment. For example, some components may be removed from all the components shown in the embodiments. In addition, components across different embodiments may be combined as appropriate.
For example, the number of magnetic poles, dimensions, shape, etc. of the rotor are not limited to the above-described embodiment, and can be variously changed according to the design. The number of slits in the permanent magnet is not limited to 3 or 5, and can be increased or decreased as needed. The slits with a short depth are not limited to the slits closest to the holding protrusions on the outer peripheral side, and a plurality of slits, for example, two slits close to the holding protrusions on the outer peripheral side are formed shorter than the cutting edge contact position. May be good.

10 ... Rotor, 12 ... Stator, 14 ... Rotor, 16 ... Stator iron core,
18 ... armature winding, 20 ... slot, 22 ... shaft, 24 ... rotor core,
M ... Permanent magnet, 30 ... Void hole, 34 ... Embedded hole, 34a ... Magnet loading area,
34b ... Inner circumference side gap, 34c ... Outer circumference side gap, 34d ... Holding protrusion,
S1, S2, S3, S4, S5 ... Slit, SA1 ... First long side,
SA2 ... 2nd long side

Claims (4)

A rotor core having a plurality of magnetic poles each having a magnet embedding hole and arranged in the circumferential direction around the central axis and a holding protrusion protruding into the magnet embedding hole.
It is formed in a rectangular cross-sectional shape having a first long side and a second long side facing each other, and a first short side and a second short side facing each other, and is spaced apart from each other in the longitudinal direction of the first long side. It has a plurality of slits extending from the first long side to the second long side, and includes a permanent magnet arranged in the magnet embedding hole and in contact with the holding protrusion.
In the cross section of the rotor core orthogonal to the central axis, the axial end of the magnetic pole and the axis extending in the radial direction through the central axis are defined as the q-axis, and electrical in the circumferential direction with respect to the q-axis. If the axis separated by 90 degrees is the d-axis,
In the permanent magnet, the first long side faces the d-axis side, the second long side faces the q-axis side, and the first short side faces the outer peripheral surface side of the rotor core. The first long side and the second long side are arranged so as to be inclined at an angle smaller than 90 degrees with respect to the d-axis, and the first short side is arranged in contact with the holding protrusion.
Assuming that a straight line extending parallel to the first long side through the contact position where the holding protrusion and the first short side are in contact is a contact virtual line, at least one of the plurality of slits close to the first short side. One slit extends from the first long side to the vicinity of the contact virtual line without crossing the contact virtual line, and at least one slit near the second short side is the first length. It extends from the side beyond the contact virtual line to the vicinity of the second long side.
Rotor. The rotor according to claim 1, wherein the plurality of slits include slits extending perpendicularly to the first long side. The rotor according to claim 1, wherein the plurality of slits include slits that are inclined and extended at an angle smaller than 90 degrees with respect to the first long side. Assuming that the line extending in the longitudinal direction of the permanent magnet through the cross-sectional center of gravity of the permanent magnet is the magnet center axis, the contact position is located between the second long side of the permanent magnet and the magnet center axis. The rotor according to any one of claims 1 to 3.

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