Rotating electrical machine

Abstract

Provided is a rotating electrical machine capable of mitigating stress concentration occurring in a rotor core portion when the rotor rotates. The rotating electrical machine includes a rotor having a rotor core portion, a first permanent magnet inserted into a first magnet cutout, and a second permanent magnet inserted into a second magnet cutout, the polarity of a magnetic pole face of the first permanent magnet that opposes a stator and the polarity of a magnetic pole face of the second permanent magnet that opposes the stator are different from each other, an inter-pole hole portion is formed between the first magnet cutout and the second magnet cutout, when a circle centered on a rotational axis and tangent to edge portions of the first magnet cutout and the second magnet cutout each on a stator side is a first circle, the inter-pole hole portion is disposed on a side opposite the stator with respect to the first circle, and an edge portion of the inter-pole hole portion on the stator side is formed along the first circle.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a rotary electric machine including a rotor core formed with a plurality of magnet cutouts and a plurality of permanent magnets respectively inserted into the plurality of magnet cutouts. BACKGROUND

[0002] In Patent Literature 1, a motor is described. The rotor portion of the motor includes a rotor core and a plurality of field magnets. The rotor core includes a plurality of magnet holding holes into which the plurality of field magnets are respectively inserted, and a plurality of flux barrier holes formed between two adjacent magnet holding holes. In each of the flux barrier holes, a reinforcing member formed of a material having a lower magnetic permeability than the rotor core is embedded.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2008-148482 SUMMARY

[0006] According to the above motor, the short circuit of the magnet flux within the rotor core can be suppressed while the strength of the rotor core is improved. However, even in the above motor, a difference in rigidity of the rotor core can occur between a magnetic pole portion in which the field magnet is embedded and a magnetic pole interval portion between two magnetic pole portions located adjacent to each other in the circumferential direction. Therefore, when the rotor rotates, there is a technical problem that stress concentration is likely to occur at the boundary portion between the magnetic pole portion and the magnetic pole interval portion.

[0007] The present disclosure was achieved to solve the above technical problem, and aims to provide a rotary electric machine in which stress concentration occurring in a rotor core when the rotor rotates can be alleviated.

[0008] The rotating electric machine of the present disclosure includes a stator and a rotor provided to freely rotate relative to the stator, the rotor having a rotor core portion formed with a first magnet cutout and a second magnet cutout that are adjacent to each other in a circumferential direction, a first permanent magnet inserted into the first magnet cutout, and a second permanent magnet inserted into the second magnet cutout, a polarity of a magnetic pole face of the first permanent magnet opposite to the stator and a polarity of a magnetic pole face of the second permanent magnet opposite to the stator being different from each other, an inter-pole hole portion extending in an axial direction being formed in the rotor core portion between the first magnet cutout and the second magnet cutout, in a cross section perpendicular to the axial direction, when a circle centered on a rotation axis of the rotor and tangent to edge portions of the first magnet cutout and the second magnet cutout on a side of the stator is defined as a first circle, the inter-pole hole portion is disposed on a side opposite to the stator relative to the first circle in the cross section, and an edge portion of the inter-pole hole portion on the side of the stator is formed along the first circle in the cross section.

[0009] According to the present disclosure, stress concentration generated in the rotor core portion when the rotor rotates can be mitigated. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a cross-sectional view showing a structure after the rotating electric machine of Embodiment 1 is cut along a rotation axis.

[0011] Figure 2 is a cross-sectional view showing a structure after a portion of the rotating electric machine of Embodiment 1 is cut perpendicular to the rotation axis.

[0012] Figure 3 is a cross-sectional view showing a structure after a portion of the rotating electric machine of Embodiment 2 is cut perpendicular to the rotation axis.

[0013] Figure 4 is a cross-sectional view showing a structure after a portion of the rotating electric machine of Embodiment 3 is cut perpendicular to the rotation axis.

[0014] Figure 5 is a cross-sectional view showing a structure after a portion of the rotating electric machine of Embodiment 4 is cut perpendicular to the rotation axis.

[0015] Figure 6 is a cross-sectional view showing a structure after a portion of the rotating electric machine of Embodiment 5 is cut perpendicular to the rotation axis.

[0016] (EXPLANATION OF SYMBOLS)

[0017] 10 frame; 11 rear side bracket; 12 front side bracket; 13 rear side bearing; 14 front side bearing; 20 stator; 21 stator core; 22 coil; 22u U-phase coil; 22v V-phase coil; 22w W-phase coil; 23 yoke portion; 24 tooth portion; 25 coil slot; 30 rotor; 31 rotor core; 31a outer circumferential surface; 32 permanent magnet; 32-1 first permanent magnet; 32-2 second permanent magnet; 32-3 third permanent magnet; 32a first magnetic pole surface; 32b second magnetic pole surface; 33 magnet slot; 33-1 first magnet slot; 33-2 second magnet slot; 33a, 33b edge portion; 34 inter-pole hole portion; 34-1 first inter-pole hole portion; 34-2 second inter-pole hole portion; 34a, 34b, 34c, 34d edge portion; 35, 35a, 35b rib portion; 36a, 36b protrusion portion; 37a, 37b magnetic gap portion; 40 magnetic pole portion; 41 inter-magnetic pole portion; 50 shaft; 51 rotational axis; 61 first circle; 62 second circle. DETAILED DESCRIPTION

[0018] Embodiment 1

[0019] A rotating electric machine of Embodiment 1 will be described. Figure 1 is a sectional view showing a structure after the rotating electric machine of the present embodiment is cut along a rotational axis. In the present embodiment, as the rotating electric machine, a motor of an inner rotor type is exemplified. In the following description, a direction along the rotational axis 51 will be referred to as an "axial direction", a direction along a circumference of a circle centered on the center axis 51 in a cross section perpendicular to the axial direction will be referred to as a "circumferential direction", and a direction along a radius of the rotor 30 in the cross section will be referred to as a "radial direction".

[0020] As shown in Figure 1 , the rotating electric machine has a frame 10, a rear side bracket 11, a front side bracket 12, a rear side bearing 13, a front side bearing 14, a stator 20, a rotor 30, and a shaft 50.

[0021] The frame 10 has a cylindrical shape. The rear side bracket 11 is embedded to one end side of the frame 10. The front side bracket 12 is embedded to the other end side of the frame 10. The rear side bearing 13 has an outer ring fixed to the rear side bracket 11 and an inner ring fixed to the shaft 50. The front side bearing 14 has an outer ring fixed to the front side bracket 12 and an inner ring fixed to the shaft 50. The shaft 50 is supported to the rear side bracket 11 and the front side bracket 12 so as to be free to rotate. The shaft 50 extends along a rotational axis 51 which is a rotation center of the rotor 30.

[0022] The stator 20 is fixed to an inner circumferential side of the frame 10. The rotor 30 is disposed to an inner circumferential side of the stator 20. An inner circumferential portion of the stator 20 and an outer circumferential portion of the rotor 30 are opposed to each other with a gap. The rotor 30 is provided so as to be free to rotate with respect to the stator 20. The shaft 50 is fixed to an inner circumferential side of the rotor 30.

[0023] The stator 20 has a stator core 21 and coils 22. The stator core 21 is formed by laminating a plurality of thin plates made of a magnetic body. The coils 22 are mounted to the stator core 21.

[0024] Figure 2 is a sectional view showing a structure after a portion of the rotary electric machine of the present embodiment is cut off perpendicularly to the rotational axis. As shown in Figure 2 The stator core 21 has a yoke portion 23 and a plurality of tooth portions 24. The yoke portion 23 has a shape of a circular ring. Each of the plurality of tooth portions 24 protrudes toward the radially inner side from the yoke portion 23. The plurality of tooth portions 24 are arranged at equal intervals in the circumferential direction. In the present embodiment, 36 tooth portions 24 are provided.

[0025] The coils 22 have a U-phase coil 22u, a V-phase coil 22v, and a W-phase coil 22w. The U-phase coil 22u, the V-phase coil 22v, and the W-phase coil 22w are sequentially wound on each tooth portion 24 in the circumferential direction.

[0026] The rotor 30 has a rotor core 31 and a plurality of permanent magnets 32. A plurality of magnet cut grooves 33 are formed in the rotor core 31. The plurality of magnet cut grooves 33 are arranged in the circumferential direction along the outer circumferential surface 31a of the rotor core 31. Each magnet cut groove 33 extends in the axial direction. In the circumferential direction of the rotor 30, a portion in which each of the plurality of magnet cut grooves 33 is formed is a magnetic pole portion 40 of the rotor 30, and a portion between two magnetic pole portions 40 adjacent to each other is a magnetic pole gap portion 41 of the rotor 30.

[0027] In the present embodiment, 24 magnet cut grooves 33 are provided. The plurality of permanent magnets 32 are respectively inserted into the plurality of magnet cut grooves 33. Each permanent magnet 32 has a shape of a rectangular flat plate. Each magnet cut groove 33 has a cross-sectional shape along a cross section of each permanent magnet 32, which is a rectangle. In Figure 2 In the cross section shown in FIG. 6, the long side direction of each magnet cut groove 33 is perpendicular to the radial direction.

[0028] Hereinafter, one of two magnet cut grooves 33 adjacent to each other in the circumferential direction is sometimes referred to as a first magnet cut groove 33-1, and the other is sometimes referred to as a second magnet cut groove 33-2. In addition, the permanent magnet 32 inserted into the first magnet cut groove 33-1 is sometimes referred to as a first permanent magnet 32-1, and the permanent magnet 32 inserted into the second magnet cut groove 33-2 is sometimes referred to as a second permanent magnet 32-2.

[0029] The orientation direction and the magnetization direction of each of the plurality of permanent magnets 32 are along the radial direction of the rotor 30. Each of the plurality of permanent magnets 32 has a first magnetic pole face 32a facing the outer circumferential side of the rotor 30 and opposing the stator 20, and a second magnetic pole face 32b facing the inner circumferential side of the rotor 30. The polarity of the first magnetic pole face 32a of the first permanent magnet 32-1 is different from the polarity of the first magnetic pole face 32a of the second permanent magnet 32-2. When the polarity of the first magnetic pole face 32a of the first permanent magnet 32-1 is the N pole, the polarity of the first magnetic pole face 32a of the second permanent magnet 32-2 is the S pole. The plurality of permanent magnets 32 are arranged such that the N pole first magnetic pole face 32a and the S pole first magnetic pole face 32a are alternately arranged along the circumferential direction of the rotor 30. Thus, the rotary electric machine 24 of the present embodiment is a 36-slot concentrated winding motor.

[0030] In a cross section perpendicular to the axial direction, the edge portion 33a on the outer circumferential side, that is, the stator 20 side, of each of the magnetic pole slots 33 is formed in a straight line along the first magnetic pole face 32a of the permanent magnet 32. In the above cross section, the edge portion 33b on the inner circumferential side, that is, the side opposite to the stator 20, of each of the magnetic pole slots 33 is formed in a straight line along the second magnetic pole face 32b of the permanent magnet 32.

[0031] In the rotor core portion 31, two inter-pole hole portions 34 are formed between the first magnetic pole slot 33-1 and the second magnetic pole slot 33-2. One of the two inter-pole hole portions 34 is adjacent to the first magnetic pole slot 33-1 and is formed as one body with the first magnetic pole slot 33-1. The other of the two inter-pole hole portions 34 is adjacent to the second magnetic pole slot 33-2 and is formed as one body with the second magnetic pole slot 33-2. Each of the inter-pole hole portions 34 extends along the axial direction. The inter-pole hole portion 34 can also function as a magnetic shield portion that reduces the short-circuit of the magnetic flux of the permanent magnet 32 in the rotor core portion 31. The inter-pole hole portion 34 can also be a hollow. Alternatively, the inter-pole hole portion 34 can be filled with a non-magnetic member.

[0032] Hereinafter, the inter-pole hole portion 34 formed as one body with the first magnetic pole slot 33-1 will be referred to as the first inter-pole hole portion 34-1, and the inter-pole hole portion 34 formed as one body with the second magnetic pole slot 33-2 will be referred to as the second inter-pole hole portion 34-2.

[0033] A rib portion 35, which is a part of the rotor core portion 31, is formed between the first inter-pole hole portion 34-1 and the second inter-pole hole portion 34-2. The rib portion 35 extends along the axial direction. In a cross section perpendicular to the axial direction, the rib portion 35 extends along the radial direction. In a case where a circumferential center portion of each of the first permanent magnet 32-1 and the second permanent magnet 32-2 is set as a magnetic pole center, that is, a d-axis, a q-axis, which is electrically or magnetically orthogonal to the d-axis, is disposed at a circumferential position shifted by 90 degrees in an electric angle from the d-axis. The rib portion 35 is formed on the q-axis and extends along the q-axis.

[0034] The first inter-pole hole portion 34-1 and the second inter-pole hole portion 34-2 are adjacent to each other in the circumferential direction with the rib portion 35 interposed therebetween. An edge portion 34a of the first inter-pole hole portion 34-1, which is located on the outer circumferential side, that is, on the side of the stator 20, and an edge portion 34b of the first inter-pole hole portion 34-1, which is located on the inner circumferential side, that is, on the side opposite to the stator 20, are connected by the rib portion 35. Similarly, an edge portion 34a of the second inter-pole hole portion 34-2 and an edge portion 34b of the second inter-pole hole portion 34-2 are connected by the rib portion 35.

[0035] In Figure 2 In the cross section shown, an edge portion 34c of the first inter-pole hole portion 34-1, which is one side surface of the rib portion 35, extends along the q-axis. In the cross section described above, an edge portion 34c of the second inter-pole hole portion 34-2, which is the other side surface of the rib portion 35, extends along the q-axis.

[0036] A distance between the edge portion 34c of the first inter-pole hole portion 34-1 and the edge portion 34c of the second inter-pole hole portion 34-2, that is, a circumferential width of the rib portion 35, is equal to or smaller than a distance between the edge portion 34a of the first inter-pole hole portion 34-1 and the outer circumferential surface 31a of the rotor core portion 31. Further, the distance between the edge portion 34c of the first inter-pole hole portion 34-1 and the edge portion 34c of the second inter-pole hole portion 34-2 is equal to or smaller than a distance between the edge portion 34a of the second inter-pole hole portion 34-2 and the outer circumferential surface 31a of the rotor core portion 31.

[0037] The first inter-pole hole portion 34-1 is provided adjacent to each of the one circumferential end side and the other circumferential end side of the first magnet cut slot 33-1. The first magnet cut slot 33-1 and the two first inter-pole hole portions 34-1 provided adjacent to both sides of the first magnet cut slot 33-1 are integrated into one hole. The second inter-pole hole portion 34-2 is provided adjacent to each of the one circumferential end side and the other circumferential end side of the second magnet cut slot 33-2. The second magnet cut slot 33-2 and the two second inter-pole hole portions 34-2 provided adjacent to both sides of the second magnet cut slot 33-2 are integrated into one hole.

[0038] Here, in Figure 2In the cross section shown, a circle that is centered on the rotational axis 51 and that is tangent to the edge portion 33a of the first magnet cutout 33-1 and the edge portion 33a of the second magnet cutout 33-2 is set as a first circle 61. The rotary electric machine of the present embodiment is of an inner rotor type, and thus the first circle 61 is an escribed circle that is centered on the rotational axis 51 and that is tangent to both the first magnet cutout 33-1 and the second magnet cutout 33-2.

[0039] Further, in Figure 2 In the cross section shown, a circle that is centered on the rotational axis 51 and that is tangent to the edge portion 33b of the first magnet cutout 33-1 and the edge portion 33b of the second magnet cutout 33-2 is set as a second circle 62. The rotary electric machine of the present embodiment is of an inner rotor type, and thus the second circle 62 is an inscribed circle that is centered on the rotational axis 51 and that is tangent to both the first magnet cutout 33-1 and the second magnet cutout 33-2.

[0040] In Figure 2 In the cross section shown, the first inter-pole hole portion 34-1 is disposed on the side opposite the stator 20 with respect to the first circle 61 as a whole. Likewise, the second inter-pole hole portion 34-2 is disposed on the side opposite the stator 20 with respect to the first circle 61 as a whole. Neither the first inter-pole hole portion 34-1 nor the second inter-pole hole portion 34-2 extends to a position further outward than the first circle 61.

[0041] In Figure 2 In the cross section shown, each of the edge portion 34a of the first inter-pole hole portion 34-1 and the edge portion 34a of the second inter-pole hole portion 34-2 is formed in an arc shape along the circumference of the first circle 61. In the present embodiment, each of the edge portion 34a of the first inter-pole hole portion 34-1 and the edge portion 34a of the second inter-pole hole portion 34-2 coincides with the circumference of the first circle 61. The edge portion 34a of the first inter-pole hole portion 34-1 is smoothly connected to one end of the edge portion 33a of the first magnet cutout 33-1. The edge portion 34a of the second inter-pole hole portion 34-2 is smoothly connected to the other end of the edge portion 33a of the second magnet cutout 33-2.

[0042] In Figure 2 In the cross section shown, the first inter-pole hole portion 34-1 is disposed on the side of the stator 20 with respect to the second circle 62 as a whole. Likewise, the second inter-pole hole portion 34-2 is disposed on the side of the stator 20 with respect to the second circle 62 as a whole. Neither the first inter-pole hole portion 34-1 nor the second inter-pole hole portion 34-2 extends to a position further inward than the second circle 62.

[0043] In Figure 2In the illustrated cross section, each of the edge portion 34b of the first interpole hole portion 34-1 and the edge portion 34b of the second interpole hole portion 34-2 is formed in an arc shape along the circumference of the second circle 62. Each of the edge portion 34b of the first interpole hole portion 34-1 and the edge portion 34b of the second interpole hole portion 34-2 is located at a position outward of the circumference of the second circle 62. Each of the edge portion 34b of the first interpole hole portion 34-1 and the edge portion 34b of the second interpole hole portion 34-2 can also coincide with the circumference of the second circle 62.

[0044] The edge portion 34b of the first interpole hole portion 34-1 is connected with the edge portion 33b of the first magnet cut 33-1 via the convex portion 36a that defines the circumferential position of the first permanent magnet 32-1. Likewise, the edge portion 34b of the second interpole hole portion 34-2 is connected with the edge portion 33b of the second magnet cut 33-2 via the convex portion 36b that defines the circumferential position of the second permanent magnet 32-2.

[0045] Thus, the first interpole hole portion 34-1 extends in the circumference from the circumferential end of the first magnet cut 33-1 to the edge portion 34c. The second interpole hole portion 34-2 extends in the circumference from the circumferential end of the second magnet cut 33-2 to the edge portion 34c. The sum of the circumferential distance of the edge portion 34c of the first interpole hole portion 34-1 from the q-axis and the circumferential distance of the edge portion 34c of the second interpole hole portion 34-2 from the q-axis is equal to the circumferential width of the rib portion 35. Therefore, the circumferential distance of the edge portion 34c of the first interpole hole portion 34-1 from the q-axis and the circumferential distance of the edge portion 34c of the second interpole hole portion 34-2 from the q-axis are set to be able to obtain sufficient strength at the rib portion 35.

[0046] Each of the first interpole hole portion 34-1 and the second interpole hole portion 34-2 is formed in the radial direction to expand between the first circle 61 and the second circle 62.

[0047] As explained above, the rotating electric machine of the present embodiment includes the stator 20 and the rotor 30 provided so as to freely rotate with respect to the stator 20. The rotor 30 has the rotor core portion 31, the first permanent magnet 32-1, and the second permanent magnet 32-2. The first magnet cutout portion 33-1 and the second magnet cutout portion 33-2, which are adjacent to each other in the circumferential direction, are formed in the rotor core portion 31. The first permanent magnet 32-1 is inserted into the first magnet cutout portion 33-1. The second permanent magnet 32-2 is inserted into the second magnet cutout portion 33-2. The polarity of the first magnetic pole face 32a, which is opposite to the stator 20, in the first permanent magnet 32-1 and the polarity of the first magnetic pole face 32a, which is opposite to the stator 20, in the second permanent magnet 32-2 are different from each other. The first inter-pole hole portion 34-1 and the second inter-pole hole portion 34-2, which extend in the axial direction, are formed in the rotor core portion 31 between the first magnet cutout portion 33-1 and the second magnet cutout portion 33-2, respectively. In a cross section perpendicular to the axial direction, a circle, which has the rotational axis 51 of the rotor 30 as a center and which is tangent to the edge portion 33a, which is located on the stator 20 side, in each of the edge portions of the first magnet cutout portion 33-1 and the second magnet cutout portion 33-2, is set as a first circle 61. In the above cross section, each of the first inter-pole hole portion 34-1 and the second inter-pole hole portion 34-2 is disposed on the side opposite to the stator 20 with respect to the first circle 61. In the above cross section, the edge portion 34a, which is located on the stator 20 side, in each of the edge portions of the first inter-pole hole portion 34-1 and the second inter-pole hole portion 34-2 is formed along the first circle 61.

[0048] In the above structure, the first inter-pole hole portion 34-1 and the second inter-pole hole portion 34-2 are provided between the first magnet cutout portion 33-1 and the second magnet cutout portion 33-2, which are adjacent to each other in the circumferential direction. In each of the first inter-pole hole portion 34-1 and the second inter-pole hole portion 34-2, at least the radial position of the edge portion 34a is close to the radial position of the edge portion 33a of each of the first magnet cutout portion 33-1 and the second magnet cutout portion 33-2. Therefore, it is possible to make the average rigidity of the rotor core portion 31 at the inter-pole portion 41 close to the average rigidity of the rotor core portion 31 at the pole portion 40. Therefore, it is possible to moderate the stress concentration at the boundary between the pole portion 40 and the inter-pole portion 41 due to the centrifugal force when the rotor 30 rotates.

[0049] Further, it is possible to moderate the stress concentration at the boundary between the pole portion 40 and the inter-pole portion 41, and therefore, it is possible to shorten the distance between each of the edge portions 33a of the first magnet cutout portion 33-1 and the second magnet cutout portion 33-2 and the outer circumferential surface 31a of the rotor core portion 31. Thus, it is possible to reduce the short circuit of the magnetic flux of the permanent magnet in the rotor 30. Therefore, it is possible to improve the torque of the rotating electric machine. In addition, it is possible to suppress the increase of the iron portion of the rotor core portion 31, and therefore, it is possible to suppress the increase of the inductance. Therefore, it is possible to improve the output of the rotating electric machine.

[0050] In the motor described in Patent Literature 1, the reinforcing member is embedded in the gap magnetic hole, and thus the strength of the rotor core portion is deviated due to the engagement state of the reinforcing member with the rotor core portion and the filling state of the reinforcing member in the gap magnetic hole. In addition, in the motor described in Patent Literature 1, the reinforcing member is embedded in the gap magnetic hole, and thus the weight of the rotor and the inertia of the rotor increase.

[0051] In contrast, in the present embodiment, the reinforcing member is not embedded in the magnet cut slot 33, and thus the strength of the rotor core portion 31 can be suppressed from being deviated, and the weight of the rotor 30 and the inertia of the rotor 30 can be suppressed from increasing.

[0052] In the rotary electric machine of the present embodiment, in a cross section perpendicular to the axial direction, the first inter-pole hole portion 34-1 and the second inter-pole hole portion 34-2 are disposed on the stator 20 side with respect to the second circle 62. Here, the second circle 62 is a circle that is centered on the rotational axis 51 in the cross section perpendicular to the axial direction, and that is tangent to the edge portion 34b on the side opposite to the stator 20 in each of the edge portions of the first magnet cut slot 33-1 and the second magnet cut slot 33-2.

[0053] According to the above structure, the radial position of the edge portion 34b in each of the first inter-pole hole portion 34-1 and the second inter-pole hole portion 34-2 can be made close to the radial position of the edge portion 33b in each of the first magnet cut slot 33-1 and the second magnet cut slot 33-2. Thus, the average rigidity of the rotor core portion 31 at the inter-pole portion 41 can be made closer to the average rigidity of the rotor core portion 31 at the pole portion 40. Thus, the stress concentration occurring at the boundary portion of the pole portion 40 and the inter-pole portion 41 can be further moderated.

[0054] In the rotary electric machine of the present embodiment, in a cross section perpendicular to the axial direction, the edge portion 34a on the stator 20 side in each of the edge portions of the first inter-pole hole portion 34-1 and the second inter-pole hole portion 34-2 coincides with the first circle 61.

[0055] According to the above structure, the radial position of the edge portion 34a in each of the first inter-pole hole portion 34-1 and the second inter-pole hole portion 34-2 can be made coincident with the radial position of the edge portion 33a in each of the first magnet cut slot 33-1 and the second magnet cut slot 33-2. Thus, the stress concentration occurring at the boundary portion of the pole portion 40 and the inter-pole portion 41 can be further moderated.

[0056] In the rotary electric machine of the present embodiment, in a cross section perpendicular to the axial direction, the long side direction of each of the first magnet cut slot 33-1 and the second magnet cut slot 33-2 is perpendicular to the radial direction. According to the above structure, the d-axis inductance can be reduced, and thus the output of the rotary electric machine can be improved.

[0057] Embodiment 2

[0058] A rotating electric machine according to Embodiment 2 will be described. Figure 3 is a sectional view showing a structure after a portion of the rotating electric machine of the present embodiment is cut off perpendicularly to the rotational axis. In addition, the same symbols are attached to structural elements having the same functions and effects as those of Embodiment 1, and the description thereof will be omitted.

[0059] As shown in Figure 3 , one inter-pole hole portion 34 is formed between the first magnet cutaway 33-1 and the second magnet cutaway 33-2. The inter-pole hole portion 34 is separated from any one of the first magnet cutaway 33-1 and the second magnet cutaway 33-2. The inter-pole hole portion 34 is surrounded by edge portions 34a and 34b each formed along the circumferential direction, and edge portions 34c and 34d each formed along the radial direction. The inter-pole hole portion 34 is disposed on the q-axis in a manner so as to span the q-axis. The q-axis passes through a circumferential center portion of the inter-pole hole portion 34.

[0060] A rib portion 35a is formed between the inter-pole hole portion 34 and the first magnet cutaway 33-1. A rib portion 35b is formed between the inter-pole hole portion 34 and the second magnet cutaway 33-2. The rib portions 35a and 35b each extend along the radial direction. The inter-pole hole portion 34 is separated from the first magnet cutaway 33-1 by the rib portion 35a. The inter-pole hole portion 34 is separated from the second magnet cutaway 33-2 by the rib portion 35b.

[0061] The inter-pole hole portion 34 as a whole is disposed on the side opposite to the stator 20 with respect to the first circle 61. The inter-pole hole portion 34 does not extend to a position further outward in the circumferential direction than the first circle 61. The edge portion 34a of the inter-pole hole portion 34, which is on the side of the stator 20, is formed in an arc shape along the circumference of the first circle 61. In the present embodiment, the edge portion 34a of the inter-pole hole portion 34 coincides with the circumference of the first circle 61.

[0062] The inter-pole hole portion 34 as a whole is disposed on the side of the stator 20 with respect to the second circle 62. The inter-pole hole portion 34 does not extend to a position further inward in the circumferential direction than the second circle 62. In the present embodiment, the edge portion 34b of the inter-pole hole portion 34, which is on the side opposite to the stator 20, is located at a position further outward in the circumferential direction than the second circle 62. The edge portion 34b of the inter-pole hole portion 34 coincides with the circumference of the second circle 62.

[0063] As described above, in the rotating electric machine of the present embodiment, the inter-pole hole portion 34 is separated from any one of the first magnet cutaway 33-1 and the second magnet cutaway 33-2. The inter-pole hole portion 34 is disposed so as to span the q-axis of the rotor 30.

[0064] According to the above-described structure, the same effects as those of Embodiment 1 can be obtained. In addition, the inter-pole hole portion 34 is disposed so as to span the q-axis, and thus the q-axis inductance can be reduced. As a result, the output of the rotating electric machine can be further improved.

[0065] Further, according to the present embodiment, each of the distance between the rib 35a and the circumferential center portion of the first magnet cut groove 33-1 and the distance between the rib 35b and the circumferential center portion of the second magnet cut groove 33-2 can be shortened compared to Embodiment 1. Thereby, the bending moment caused by the centrifugal force can be reduced, and thus the stress generated in the rotor core portion 31 due to the centrifugal force can be further reduced.

[0066] Embodiment 3

[0067] A rotating electric machine according to Embodiment 3 will be described. Figure 4 is a sectional view showing a structure after a portion of the rotating electric machine of the present embodiment is cut perpendicular to the rotational axis. In addition, the same reference numerals are assigned to structural elements having the same function and effect as those of Embodiment 1 or 2, and the description thereof is omitted.

[0068] As shown in Figure 4 , a plurality of first magnet cut groove groups and a plurality of second magnet cut groove groups are formed in the rotor core portion 31. Each of the plurality of first magnet cut groove groups has two first magnet cut grooves 33-1 arranged in a V shape. Each of the plurality of second magnet cut groove groups has two second magnet cut grooves 33-2 arranged in a V shape. The plurality of first magnet cut groove groups and the plurality of second magnet cut groove groups are alternately arranged along the circumferential direction. In the present embodiment, 12 groups of first magnet cut groove groups and 12 groups of second magnet cut groove groups are provided.

[0069] A first permanent magnet 32-1 is inserted in each of the first magnet cut groove groups 33-1. A second permanent magnet 32-2 is inserted in each of the second magnet cut groove groups 33-2. The first permanent magnet 32-1 and the second permanent magnet 32-2 each have a rectangular flat shape. Two permanent magnets 32 constituting one magnetic pole are arranged in a V shape. In the rotor core portion 31, 24 first permanent magnets 32-1 and 24 second permanent magnets 32-2, that is, a total of 48 permanent magnets 32 are embedded. Thereby, a 24-pole rotor 30 is constituted.

[0070] In the cross section shown in Figure 4 , a magnetic separation portion 37a formed integrally with the first magnet cut groove 33-1 is formed at both ends in the long direction of each first magnet cut groove 33-1. Similarly, a magnetic separation portion 37b formed integrally with the second magnet cut groove 33-2 is formed at both ends in the long direction of each second magnet cut groove 33-2.

[0071] An inter-pole hole portion 34 is formed between the first magnet cutout 33-1 and the second magnet cutout 33-2 that are adjacent to each other in the circumferential direction. The inter-pole hole portion 34 is separated from any one of the first magnet cutout 33-1 and the second magnet cutout 33-2. The inter-pole hole portion 34 is surrounded by edge portions 34a and 34b that are formed along the circumferential direction, respectively, and edge portions 34c and 34d that are formed along the radial direction, respectively. The inter-pole hole portion 34 is disposed on the q-axis in a manner that spans the q-axis. The q-axis passes through a circumferential center portion of the inter-pole hole portion 34.

[0072] The inter-pole hole portion 34 is disposed on the side opposite to the stator 20 with respect to the first circle 61. The edge portion 34a of the inter-pole hole portion 34, which is on the side of the stator 20, is formed along the circumference of the first circle 61. In the present embodiment, the edge portion 34a of the inter-pole hole portion 34 is located on the outer circumferential side than the first circle 61. The edge portion 34a of the inter-pole hole portion 34 can also coincide with the circumference of the first circle 61.

[0073] The inter-pole hole portion 34 is disposed on the side of the stator 20 with respect to the second circle 62. In the present embodiment, the edge portion 34b of the inter-pole hole portion 34, which is on the side opposite to the stator 20, is located on the inner circumferential side than the second circle 62. The edge portion 34b of the inter-pole hole portion 34 can also coincide with the circumference of the second circle 62.

[0074] A rib portion 35a is formed between the inter-pole hole portion 34 and the first magnet cutout 33-1 and the magnetic separation portion 37a. A rib portion 35b is formed between the inter-pole hole portion 34 and the second magnet cutout 33-2 and the magnetic separation portion 37b.

[0075] According to the present embodiment, the same effects as those of Embodiment 2 can be obtained. In a rotary electric machine in which two permanent magnets 32 are disposed in a V-shape as in the present embodiment, the weight of the outer circumferential side portion of the one group of magnet cutout groups becomes larger as compared with a rotary electric machine in which the pole faces of the respective permanent magnets 32 are disposed along the circumferential direction as in Embodiments 1 and 2. Therefore, the bending stress that occurs in the rib portions 35a and 35b due to centrifugal force tends to become larger. Therefore, in the rotary electric machine of the present embodiment, the same stress reduction effects as those of Embodiment 2 can be exerted more efficiently.

[0076] Further, the inter-pole hole portion 34 of the present embodiment is formed in a rectangular shape having a constant circumferential width. Thereby, it is possible to suppress the case where the magnetic flux of the permanent magnet 32 is hindered by the inter-pole hole portion 34, and thus it is possible to suppress the adverse effects on the torque of the rotary electric machine.

[0077] On the other hand, the inter-pole hole portion 34 of the present embodiment can also be provided so as to extend to the inner side portion of the permanent magnet 32. Thereby, it is possible to make the rigidity of the rotor core portion 31 in the vicinity of the magnet cutout 33 more uniform, and thus it is possible to further moderate the stress concentration that occurs in the rotor core portion 31 due to centrifugal force.

[0078] Embodiment 4

[0079] A rotating electric machine according to Embodiment 4 will be described. Figure 5 is a sectional view showing a structure after a portion of the rotating electric machine of the present embodiment is cut off perpendicularly to the rotational axis. Further, the same symbols are attached to structural elements having the same functions and effects as those of any one of Embodiments 1 to 3, and the description thereof is omitted.

[0080] As shown in Figure 5 , the stator core portion 21 has a yoke portion 23 of a circular ring shape and 72 tooth portions 24 protruding from the yoke portion 23 to the radially inner side. The 72 tooth portions 24 are arranged at equal intervals in the circumferential direction. The coil cut grooves 25 are formed between two tooth portions 24 adjacent to each other. Among the 72 coil cut grooves 25, the U-phase coil 22u, the V-phase coil 22v, and the W-phase coil 22w are arranged to be arranged in the order of U-phase coil, U-phase coil, W-phase coil, W-phase coil, V-phase coil, V-phase coil, U-phase coil… along the circumferential direction. Thus, the rotating electric machine of the present embodiment is a full-pitch distributed-winding type motor having 24 poles and 72 cut grooves per pole per phase and two windings.

[0081] The structure of the rotor 30 is the same as that of Embodiment 3. According to the present embodiment, the same effects as those of Embodiment 3 can be obtained.

[0082] Embodiment 5

[0083] A rotating electric machine according to Embodiment 5 will be described. Figure 6 is a sectional view showing a structure after a portion of the rotating electric machine of the present embodiment is cut off perpendicularly to the rotational axis. Further, the same symbols are attached to structural elements having the same functions and effects as those of any one of Embodiments 1 to 4, and the description thereof is omitted.

[0084] As shown in Figure 6 , one inter-pole hole portion 34 is formed between the first magnet cut groove 33-1 and the second magnet cut groove 33-2. The inter-pole hole portion 34 is separated from any one of the first magnet cut groove 33-1 and the second magnet cut groove 33-2. The third permanent magnet 32-3 is inserted into the inter-pole hole portion 34. In the circumferential direction, the third permanent magnet 32-3 is located between the first permanent magnet 32-1 and the second permanent magnet 32-2. The third permanent magnet 32-3 functions as an inter-pole permanent magnet that supplements the excitation magnetic flux of the first permanent magnet 32-1 and the second permanent magnet 32-2.

[0085] The orientation direction of the third permanent magnet 32-3 is along the circumferential direction of the rotor 30. The third permanent magnet 32-3 is magnetized along the circumferential direction. That is, the magnetization direction of the third permanent magnet 32-3 is orthogonal to the respective magnetization directions of the first permanent magnet 32-1 and the second permanent magnet 32-2. It is preferable that the magnetization directions of two third permanent magnets 32-3 adjacent in the circumferential direction sandwiching the first permanent magnet 32-1 and the second permanent magnet 32-2 are opposite to each other. In this case, the arrangement of the permanent magnets in the circumferential direction of the rotor 30 is a Halbach arrangement. The other structures are the same as in Embodiment 2.

[0086] As explained above, in the rotary electric machine of the present embodiment, the rotor 30 further has the third permanent magnet 32-3 inserted into the inter-pole hole portion 34. The third permanent magnet 32-3 is magnetized along the circumferential direction.

[0087] According to the above structure, in addition to being able to obtain the same effects as in Embodiment 2, the excitation magnetic flux of the first permanent magnet 32-1 and the second permanent magnet 32-2 can be supplemented by the third permanent magnet 32-3. Thus, the torque and the output of the rotary electric machine can be further improved.

[0088] In the above-described Embodiments 1 to 5, a motor is exemplified as the rotary electric machine, but the rotary electric machine of the above-described Embodiments 1 to 5 can also operate as a generator. In the case where the rotary electric machine of the above-described Embodiments 1 to 5 operates as a generator, the same effects as in the case where the rotary electric machine operates as a motor can be obtained.

[0089] In the above-described Embodiments 1 to 5, the inter-pole hole portion 34 can also be divided into a plurality along the circumferential direction. According to the above structure, a rib portion extending along the radial direction can be additionally provided, and thus the stress generated in the rotor core portion 31 due to centrifugal force can be further reduced.

[0090] In the above-described Embodiments 1 to 5, an inner rotor type rotary electric machine in which the rotor 30 is disposed on the inner peripheral side of the stator 20 is exemplified, but a rotary electric machine of an outer rotor type in which the rotor 30 is disposed on the outer peripheral side of the stator 20 can also be used. In the case of the rotary electric machine of the outer rotor type, the first circle 61 becomes an incircle that is centered on the rotational axis 51 and internally tangent to both the first magnet cutaway groove 33-1 and the second magnet cutaway groove 33-2. The second circle 62 becomes an excircle that is centered on the rotational axis 51 and externally tangent to both the first magnet cutaway groove 33-1 and the second magnet cutaway groove 33-2. The same effects as in the rotary electric machine of the inner rotor type can be obtained even in the rotary electric machine of the outer rotor type.

[0091] In the above-described embodiments 1 to 5, the edge portion 34a of the inter-pole hole portion 34 can be formed in a circular arc shape or in a straight line shape. Similarly, the edge portion 34b of the inter-pole hole portion 34 can be formed in a circular arc shape or in a straight line shape. In a case where both the edge portion 34a and the edge portion 34b are formed in a straight line shape, the inter-pole hole portion 34 can also be formed in a rectangular shape.

[0092] The above-described embodiments 1 to 5 can be implemented in combination with each other.

Claims

1. A rotary electric machine characterized by comprising: comprises: a stator; and a rotor provided so as to freely rotate relative to the stator, the rotor having: a rotor core formed with a first magnet cut groove and a second magnet cut groove that are adjacent to each other in a circumferential direction; a first permanent magnet inserted into the first magnet cut groove; and a second permanent magnet inserted into the second magnet cut groove, the polarity of a magnetic pole face of the first permanent magnet that opposes the stator and the polarity of a magnetic pole face of the second permanent magnet that opposes the stator are different from each other, an inter-pole hole portion extending in an axial direction is formed between the first magnet cut groove and the second magnet cut groove in the rotor core, in a cross section perpendicular to the axial direction, when a circle that is centered on a rotational axis of the rotor and that is tangent to an edge portion of each of the first magnet cut groove and the second magnet cut groove that is on a stator side is taken as a first circle, in the cross section, the inter-pole hole portion is disposed on a side opposite the stator relative to the first circle, in the cross section, an edge portion of the inter-pole hole portion that is on the stator side is formed along the first circle, the long side direction of the first magnet cut groove and the second magnet cut groove is disposed obliquely relative to the circumferential direction so that, of both end portions of the long side direction of each of the first magnet cut groove and the second magnet cut groove, the end portion on the side closer to the inter-pole hole portion is on the side closer to the first circle than the other end portion, on the end portion on the side closer to the inter-pole hole portion, a first rib portion is provided between the first magnet cut groove and the inter-pole hole portion, and a second rib portion is provided between the second magnet cut groove and the inter-pole hole portion.

2. The rotary electric machine according to claim 1, wherein, in the cross section, when a circle that is centered on the rotational axis and that is tangent to an edge portion of each of the first magnet cut groove and the second magnet cut groove that is on a side opposite the stator is taken as a second circle, in the cross section, the inter-pole hole portion is disposed on the stator side relative to the second circle.

3. The rotary electric machine according to claim 1, wherein, in the cross section, the edge portion of the inter-pole hole portion that is on the stator side coincides with the first circle.

4. The rotary electric machine according to claim 2, wherein, in the cross section, the edge portion of the inter-pole hole portion that is on the stator side coincides with the first circle.

5. The rotary electric machine according to any one of claims 1 to 4, wherein, the inter-pole hole portion is separated from any one of the first magnet cut groove and the second magnet cut groove, the inter-pole hole portion is provided so as to span a q-axis of the rotor.

6. The rotary electric machine according to claim 5, wherein, the rotor further has a third permanent magnet inserted into the inter-pole hole portion, the third permanent magnet is magnetized in the circumferential direction.

7. The rotary electric machine according to any one of claims 1 to 4 and claim 6, wherein, In the cross section, the long side direction of each of the first magnet cutout and the second magnet cutout is perpendicular to the radial direction.

8. The rotary electric machine according to claim 5, wherein, In the cross section, the long side direction of each of the first magnet cutout and the second magnet cutout is perpendicular to the radial direction.

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