Rotor for rotating electrical machine

Abstract

To further optimize a magnetic path and further reduce centrifugal force in a multilayer arrangement structure having a W-shaped magnet hole when viewed in a shaft direction.SOLUTION: A rotor for a rotary electric machine is disclosed that includes a rotor core, a first permanent magnet in a first magnet hole, and a second permanent magnet in a second magnet hole. The first magnet hole has a shape protruding radially inward on one side in a circumferential direction with respect to a d-axis. The second magnet hole has a shape protruding inward in a core radial direction on one side in a circumferential direction with respect to the d-axis. With at least one of the first magnet hole and the second magnet hole, a portion extending on both sides in a circumferential direction with respect to the d-axis while sandwiching the d-axis or passing through the d-axis has a form protruding outward in a core radial direction when viewed in a shaft direction, and the form protruding inward in the core radial direction has a curved portion when viewed in the shaft direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a rotor for a rotating electric machine. [Background technology]

[0002] A two-layer structure is known in which multiple permanent magnets are arranged in two layers in a rotor core. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-107370 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of such a two-layer structure (the same applies to a multi-layer structure of three or more layers), the magnet holes are sometimes formed (or arranged) in a W-shape centered on the d-axis when viewed in the axial direction in order to deal with the increase in centrifugal force that accompanies the higher rotation speeds of rotating electrical machines. However, there is room for improvement in the details of this W-shape from the perspective of further optimizing the magnetic path and further reducing centrifugal force.

[0005] Therefore, in one aspect, the present disclosure aims to further optimize the magnetic path and further reduce the centrifugal force in a multi-layer arrangement structure in which the magnet holes are W-shaped when viewed in the axial direction. [Means for solving the problem]

[0006] In one aspect, a rotor core in which first magnet holes are formed symmetrically with respect to the d axis when viewed in the axial direction, and second magnet holes including two or more hole portions that are connected in the circumferential direction are formed symmetrically with respect to the d axis when viewed in the axial direction; a first permanent magnet disposed in the first magnet hole; a second permanent magnet disposed in the second magnet hole; the rotor core includes a first portion located radially outward of the first magnet holes and forming the outer peripheral surface of the rotor core, a second portion passing between the first magnet holes and the second magnet holes and extending on both circumferential sides to the outer peripheral surface of the rotor core, and a third portion passing radially inward of the second magnet holes and extending on both circumferential sides to the outer peripheral surface of the rotor core, the first magnet hole has a shape that is convex toward the radially inward side of the rotor core on one circumferential side with respect to the d axis, the second magnet hole has a shape that is convex toward the radially inward side of the rotor core on one circumferential side with respect to the d axis, A rotor for a rotating electric machine is provided in which at least one of the first magnet hole and the second magnet hole has a hole portion extending circumferentially on both sides of the d axis, across or through the d axis, that has a convex shape radially outward from the rotor core when viewed in the axial direction, and the convex shape radially inward from the rotor core has a curved portion when viewed in the axial direction. [Effects of the Invention]

[0007] According to one aspect, the present disclosure makes it possible to further optimize the magnetic path and further reduce centrifugal force in a multi-layer structure in which magnet holes are W-shaped when viewed in the axial direction. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view schematically showing a cross-sectional structure of a motor according to an embodiment. [Figure 2] FIG. [Figure 3] FIG. 3 is an enlarged view of a portion relating to one magnetic pole shown in FIG. [Figure 4] 3 (one side in the circumferential direction with respect to the d-axis). FIG. [Figure 5A] FIG. 10 is a diagram illustrating a configuration of a comparative example. [Figure 5B] FIG. 10 is a diagram illustrating a configuration of another comparative example. [Figure 6] 5B is a diagram illustrating some of the effects of the present embodiment in comparison with the comparative example of FIG. 5A. FIG. [Figure 7] FIG. 10 is a plan view showing a part of a rotor core according to a second embodiment. [Figure 8] FIG. 10 is a plan view showing a part of a rotor core according to a third embodiment. [Figure 9] FIG. 10 is a plan view showing a part of a rotor core according to a fourth embodiment. [Figure 10] FIG. 10 is a plan view showing a part of a rotor core according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Each embodiment will be described in detail below with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are merely examples and are not intended to limit the scope of the invention. In addition, shapes and the like in the drawings may be partially exaggerated for the sake of explanation.

[0010] Fig. 1 is a cross-sectional view that schematically shows the cross-sectional structure of a motor 1 according to one embodiment. Fig. 2 is a cross-sectional view (a cross-sectional view taken along a plane perpendicular to the axial direction) of a rotor 30. Note that in Fig. 2 and other figures, for ease of viewing, reference symbols may be assigned only to some of the parts that exist with the same attribute.

[0011] 1 shows a rotating shaft 12 of a motor 1. In the following description, the axial direction refers to the direction in which the rotating shaft (center of rotation) 12 of the motor 1 extends, and the radial direction refers to the radial direction centered on the rotating shaft 12. Therefore, the radially outer side refers to the side away from the rotating shaft 12, and the radially inner side refers to the side toward the rotating shaft 12. Furthermore, the circumferential direction corresponds to the direction of rotation around the rotating shaft 12.

[0012] The motor 1 may be a motor for driving a vehicle, such as that used in a hybrid vehicle or an electric vehicle, but the motor 1 may also be used for any other purpose.

[0013] The motor 1 is an inner rotor type, and the stator 21 is provided so as to surround the radial outside of the rotor 30. The radial outside of the stator 21 is fixed to the motor housing 10. The stator 21 includes a stator core 211 made of, for example, annular laminated steel plates of a magnetic material, and a plurality of slots (not shown) are formed radially inside the stator core 211, around which coils 212 are wound.

[0014] The rotor 30 is disposed radially inside the stator 21 .

[0015] The rotor 30 includes a rotor core 32, a rotor shaft 34, end plates 35A and 35B, and permanent magnets 61 and 62.

[0016] The rotor core 32 is fixed to the radially outer surface of the rotor shaft 34 and rotates integrally with the rotor shaft 34. The rotor core 32 has an axial hole 320 (see FIG. 2 ), into which the rotor shaft 34 is fitted. The rotor core 32 may be fixed to the rotor shaft 34 by shrink fitting, press fitting, or the like. For example, the rotor core 32 may be connected to the rotor shaft 34 by a key connection or a spline connection. The rotor shaft 34 is rotatably supported in the motor housing 10 via bearings 14 a and 14 b. The rotor shaft 34 defines the rotary axis 12 of the motor 1.

[0017] The rotor core 32 is formed, for example, from annular laminated steel plates of a magnetic material. Permanent magnets 61, 62 (see FIG. 2) are embedded inside the rotor core 32. That is, the rotor core 32 has magnet holes 321, 322 (see FIG. 2) that penetrate in the axial direction, and the permanent magnets 61, 62 are inserted into and fixed in the magnet holes 321, 322. In a modified example, the rotor core 32 may be formed from a green compact obtained by compressing and solidifying magnetic powder.

[0018] The rotor core 32 has an annular shape when viewed in the axial direction, and the outer peripheral surface of the rotor core 32 includes a portion having a constant outer diameter. In a modified example, the circular shape of the rotor core 32 does not need to be a perfect circle, and may be a circular shape having a notch (e.g., a weld groove) in part.

[0019] 2, rotor core 32 has a rotationally symmetric shape about rotation axis 12 when viewed in the axial direction. In the example shown in FIG. 2, rotor core 32 has a shape in which each pair of permanent magnets 61, 62 overlaps every 45 degrees of rotation about rotation axis 12.

[0020] The multiple permanent magnets 61, 62 may be sintered magnets, or may be made of a bonded magnet material (hereinafter simply referred to as "bonded magnet material"), which is a mixture of magnetic powder and a binder. In this embodiment, as an example, as shown in FIG. 2, the multiple permanent magnets 61, 62 are arranged in pairs when viewed in the axial direction. In this case, a common magnetic pole is formed between the paired permanent magnets 61 and between the paired permanent magnets 62. The multiple permanent magnets 61, 62 are arranged in a manner such that south poles and north poles appear alternately in the circumferential direction. In this embodiment, the number of magnetic poles is eight, but the number of magnetic poles is arbitrary.

[0021] 1 shows the motor 1 having a specific structure, but the structure of the motor 1 is not limited to such a specific structure. For example, in FIG. 1, the rotor shaft 34 is hollow, but it may be solid.

[0022] Next, the rotor core 32 and the permanent magnets 61, 62 will be described in more detail with reference to Figure 3 and subsequent figures. Although the configuration relating to one magnetic pole will be described below, the configurations relating to the other magnetic poles may be similar.

[0023] FIG. 3 is an enlarged view of a portion of one magnetic pole shown in FIG. 2. The configuration of one magnetic pole is basically symmetrical with respect to the d-axis (indicated in English as "d-axis" in FIG. 3) which corresponds to the main magnetic flux direction (direction of the field pole). Hereinafter, the side farther from the d-axis refers to the side away from the d-axis, and the side closer to the d-axis refers to the side closer to the d-axis. Furthermore, "both circumferential sides of the d-axis" refer to both circumferential sides sandwiching the d-axis, and refer to both circumferential sides of the d-axis with the d-axis as the center. Furthermore, "one circumferential side of the d-axis" refers to any one of both circumferential sides of the d-axis.

[0024] The rotor core 32 is formed with a magnet hole 321 (hereinafter referred to as the "first magnet hole 321") and a magnet hole 322 (hereinafter referred to as the "second magnet hole 322"). The first magnet hole 321 includes two or more hole portions that are circumferentially connected and symmetrical about the d-axis when viewed in the axial direction, and the second magnet hole 322 includes two or more hole portions that are circumferentially connected and symmetrical about the d-axis when viewed in the axial direction. The first magnet hole 321 includes two or more hole portions that are circumferentially connected radially outward of the second magnet hole 322 via a second portion 3212, which will be described later. Note that the "connected" refers to a connected state via various bridges, which will be described later.

[0025] The first magnet hole 321 includes a hole portion on the d-axis and two pairs of hole portions located on both sides of the d-axis in the circumferential direction. However, in a modified example, the hole portion on the d-axis of the first magnet hole 321 may be separated on both sides of the d-axis in the circumferential direction of the d-axis. Alternatively, the first magnet hole 321 may not have a hole portion on the d-axis and may only include hole portions on both sides of the d-axis in the circumferential direction of the d-axis (see FIG. 9 ). Alternatively, the first magnet hole 321 may be formed by a collection of many small hole portions. In this case, the shape of the first magnet hole 321 corresponds to the overall shape (arrangement) of the collection of many small hole portions. A permanent magnet 61 is provided in each hole portion of the first magnet hole 321. In this case, the permanent magnet 61 may be arranged without any gaps in the first magnet hole 321, or gaps (flux barriers) may be provided between the first magnet hole 321 and the permanent magnet 61 at both longitudinal ends of the permanent magnet 61. Note that these gaps may be hollow or filled with resin or the like. Furthermore, a plurality of permanent magnets 61 may be arranged in one hole portion of the first magnet hole 321.

[0026] Second magnet hole 322 is provided radially inward of first magnet hole 321. That is, second magnet hole 322 is provided in a manner facing first magnet hole 321 from the radially inner side.

[0027] In this embodiment, the second magnet hole 322 includes a total of four hole portions, each formed in pairs on either side of the d-axis in the circumferential direction. That is, the second magnet hole 322 has two hole portions formed on one side of the d-axis in the circumferential direction and two hole portions formed on the other side of the d-axis in the circumferential direction. In this way, in this embodiment, a total of four hole portions form the second magnet hole 322 for one magnetic pole. However, in a modified example, like the first magnet hole 321, the second magnet hole 322 may be composed of a hole portion on the d-axis and two paired hole portions located on both sides of the d-axis in the circumferential direction. Alternatively, the second magnet hole 322 may be formed by a collection of a larger number of small hole portions. In either case, the shape of the second magnet hole 322 corresponds to the shape (arrangement) of the collection of multiple hole portions as a whole. A permanent magnet 62 is provided in each hole portion of the second magnet hole 322. In this case, the permanent magnet 62 may be placed without any gaps in the second magnet hole 322, but gaps may be provided between the second magnet hole 322 and the permanent magnet 62 at both longitudinal ends of the permanent magnet 62. Note that these gaps may be hollow or may be filled with resin or the like. Furthermore, multiple permanent magnets 62 may be placed in one hole portion of the second magnet hole 322.

[0028] By having such a first magnet hole 321 and a second magnet hole 322, the rotor core 32 has three parts 3211, 3212, and 3213 (hereinafter also referred to as the first part 3211, the second part 3212, and the third part 3213) that are connected radially only via bridges.

[0029] Specifically, the first portion 3211 extends radially outward from the first magnet hole 321. The first portion 3211 forms a part of the outer circumferential surface 328 of the rotor core 32.

[0030] The second portion 3212 passes between the second magnet hole 322 and the first magnet hole 321, and extends on both circumferential sides to the outer peripheral surface 328 of the rotor core 32. The second portion 3212 forms part of the outer peripheral surface 328 of the rotor core 32 on both circumferential sides of the first portion 3211. The second portion 3212 forms a magnetic path for the q-axis magnetic flux. Specifically, the q-axis magnetic flux flows from one end of the second portion 3212 to the other end, passing between the second magnet hole 322 and the first magnet hole 321.

[0031] The third portion 3213 passes radially inward of the second magnet hole 322 and extends on both circumferential sides to the outer peripheral surface 328 of the rotor core 32. The third portion 3213 forms part of the outer peripheral surface 328 of the rotor core 32 on both circumferential sides of the second portion 3212.

[0032] In this embodiment, the mass of the third portion 3213 may be significantly greater than the mass of the second portion 3212, and the mass of the second portion 3212 is significantly greater than the mass of the first portion 3211.

[0033] Furthermore, the rotor core 32 has these three portions 3211, 3212, and 3213, and thus has a plurality of bridges 41, 42, 43, 44, and 45 connecting the three portions 3211, 3212, and 3213.

[0034] The bridges 41 (hereinafter referred to as "first bridges 41") support the first portion 3211 radially outward relative to the second portion 3212. That is, the first bridges 41 connect the second portion 3212 and the first portion 3211 and extend in the circumferential direction. The first bridges 41 are provided in pairs on both circumferential sides of the first portion 3211.

[0035] The bridges 42 (hereinafter referred to as "second bridges 42") support the second portion 3212 radially outward relative to the third portion 3213. That is, the second bridges 42 connect the third portion 3213 and the second portion 3212 and extend in the circumferential direction. The second bridges 42 are provided in pairs on both sides of the second portion 3212 in the circumferential direction.

[0036] The bridges 43 support the first portion 3211 with respect to the second portion 3212, radially inward of the first bridges 41. In the example shown in Fig. 3, the bridges 43 are arranged in pairs on both sides in the circumferential direction of the d-axis.

[0037] The bridge 44 (hereinafter referred to as the "center bridge 44") supports the second portion 3212 relative to the third portion 3213 on the d axis.

[0038] The bridge 45 (hereinafter referred to as the "intermediate bridge 45") supports the second portion 3212 relative to the third portion 3213 radially outward from the center bridge 44 and radially inward from the second bridge 42.

[0039] Next, further characteristic configurations of this embodiment will be described with reference to Figures 4 and beyond. Figure 4 is a further enlarged view of a portion of Figure 3 (one circumferential side with respect to the d-axis) and is a view illustrating lines for explaining shape characteristics. Figure 5A is a view illustrating the configuration of a rotor core 32' of a comparative example, and Figure 5B is a view illustrating the configuration of a rotor core 32" of another comparative example. Figure 6 is a view illustrating some of the effects of this embodiment in comparison with the comparative example of Figure 5A. In Figures 4 and 5A, the flow of q-axis magnetic flux is schematically indicated by arrows M5 and M5', respectively.

[0040] In the following description, various arrangements and shapes represent arrangements and shapes when viewed in the axial direction unless otherwise specified.

[0041] In this embodiment, the second magnet hole 322 has a W-shape centered on the d-axis. Specifically, the portion of the second magnet hole 322 closer to the d-axis has a shape that convex radially outward around the d-axis, and on one circumferential side of the d-axis, has a shape that convex radially inward. In this embodiment, the portion closer to the d-axis corresponds to the hole portions 322-1 on both circumferential sides of the center bridge 44. The portions on one circumferential side of the d-axis that have a shape that convex radially inward correspond to the hole portions 322-1 and 322-2 on both circumferential sides of one intermediate bridge 45.

[0042] When the portion of the second magnet hole 322 closer to the d axis has a shape that is convex radially outward about the d axis, the angle α between the d axis and the geometric center line LN4 of the portion closer to the d axis becomes an acute angle on the radially inward side, as shown in Fig. 4. When the portion of the second magnet hole 322 closer to the d axis has an arc shape as shown in Fig. 4, the geometric center line LN4 may be tangent to the end of the arc on the d axis side. When the portion of the second magnet hole 322 closer to the d axis has a shape that is convex radially inward on one circumferential side of the d axis, the geometric center line LN5 of the second magnet hole 322 as a whole has a shape that is convex radially inward on one circumferential side of the d axis, as shown in Fig. 4.

[0043] In this embodiment, as shown in FIG. 4, this radially inwardly convex shape has a curved portion (see R41, R42) with a center of curvature on the d-axis side (radially outward). When the radially inwardly convex shape has a curved portion, the center line LN5 of the shape of the second magnet hole 322 as a whole has a curved portion with a center of curvature on the d-axis side (radially outward) on one circumferential side of the d-axis. Note that in the example shown in FIG. 4, the second magnet hole 322 has a curved portion (see R41, R42) on both sides of the intermediate bridge 45, but only one side may have a curved portion (R41 or R42). In addition, the second magnet hole 322 does not need to be entirely curved; for example, only a portion close to the intermediate bridge 45 may be curved. In addition, the radius of curvature of the curved portion may be constant or may vary within one curved portion.

[0044] In the comparative example shown in FIG. 5A, the second magnet hole 322′ into which the permanent magnet 62′ is inserted has hole portions 322′-1 and 322′-2 that are W-shaped about the d-axis, similar to the present embodiment. However, unlike the present embodiment, the convex shape of the second magnet hole 322′ does not have a curved portion. In other words, the second magnet hole 322′ is linear. In another comparative example shown in FIG. 5B, the second magnet hole 322″ into which the permanent magnet 62″ is inserted has hole portions 322″-1 and 322″-2 that are V-shaped about the d-axis, rather than W-shaped about the d-axis.

[0045] Meanwhile, in the case of another comparative example shown in FIG. 5B, as shown schematically in FIG. 5B, there is no convex shape that extends radially outward from the d-axis, and therefore the magnetic path width L50 on the side closer to the d-axis is significantly larger than the magnetic path width L61 on the side farther from the d-axis. In this case, the mass of the second portion 3212″ increases, and stress concentration due to centrifugal force is likely to become significant in each bridge (particularly bridges 42″, 44″, 45″ between the second portion 3212″ and the third portion 3213).

[0046] In this regard, according to this embodiment (as well as the comparative example shown in FIG. 5A), second magnet hole 322 has a W-shape centered on the d-axis, which makes it possible to efficiently reduce the mass of second portion 3212 while ensuring the required magnetic path width L61. This effectively reduces stress in each bridge (particularly bridges 42, 44, 45 between second portion 3212 and third portion 3213) caused by centrifugal force.

[0047] On the other hand, in the comparative example shown in FIG. 5A, because second magnet hole 322′ has a linear shape, there is a portion (location of magnetic path width L60′) where the magnetic path width is significantly larger than magnetic path width L50, as shown in comparison with FIG. 6. Specifically, in second portion 3212′, a relatively large magnetic path width L60′ occurs in the center of one side of second magnet hole 322′ with respect to the d axis (a shape that is convex radially inward) of the W-shape of second magnet hole 322′. When such a relatively large magnetic path width L60′ occurs, the mass of second portion 3212′ increases accordingly, and stress concentration due to centrifugal force tends to become significant in each bridge (particularly bridges 42′, 44′, 45′ between second portion 3212′ and third portion 3213).

[0048] In contrast, according to the present embodiment, the second magnet hole 322 has the curved portions (see R41 and R42) as described above, and therefore, as shown in FIG. 6, the above-described disadvantages occurring in the comparative example shown in FIG. 5A can be eliminated or reduced. Specifically, according to the present embodiment, in the second portion 3212, the magnetic path width L60 occurring in the central portion of one side portion (the radially inward convex portion) of the W-shape of the second magnet hole 322 relative to the d-axis can be significantly smaller than the magnetic path width L60' in the comparative example. For example, according to the present embodiment, the magnetic path width L60 can be made substantially equal to the magnetic path width L61. As a result, according to the present embodiment, the necessary magnetic path width (e.g., a magnetic path width equal to or greater than the magnetic path width L61) can be ensured throughout the entire second portion 3212, while effectively reducing stress in each bridge 42, 44, 45 due to centrifugal force.

[0049] Furthermore, according to this embodiment, the first magnet hole 321 also has a W-shape, and therefore, based on the same principle, it is possible to effectively reduce stress in each bridge 41, 43 caused by centrifugal force. When the first magnet hole 321 has a W-shape, it is possible to reduce the mass of the first portion 3211, but on the other hand, it is likely that the mass of the portion corresponding to the second portion 3212 will increase. For example, in another comparative example shown in FIG. 5B, the first magnet hole 321″ has a W-shape, and therefore the width (radial width) of the second portion 3212″ on the d-axis is increased accordingly, and the mass of the second portion 3212″ is likely to increase.

[0050] In contrast to this, according to this embodiment, since the second magnet hole 322 as well as the first magnet hole 321 have a W-shape, the mass of each of the first portion 3211 and the second portion 3212 can be reduced efficiently.

[0051] Furthermore, in this embodiment, when the permanent magnets 61, 62 are formed from a bonded magnetic material, it is possible to fill the first magnet hole 321 and the second magnet hole 322 with the permanent magnets 61, 62 without any gaps. In this case, the amount (volume) of the permanent magnets 61, 62 occupying the first magnet hole 321 and the second magnet hole 322, respectively, is maximized, thereby improving the torque characteristics of the motor 1. In this configuration, the permanent magnets 61, 62 each have a curved shape corresponding to the curved portions of the first magnet hole 321 and the second magnet hole 322. However, in a modified example, even when the permanent magnets 61, 62 are formed from a bonded magnetic material, a flux barrier (air gap) may be provided. Also, only one of the permanent magnets 61, 62 may be formed from a bonded magnetic material. Also, only a portion of the permanent magnet 61 and / or only a portion of the permanent magnet 62 may be formed from a bonded magnetic material.

[0052] Next, several other embodiments will be described with reference to Figure 7 onwards. Hereinafter, the embodiment described above with reference to Figures 2 and 3 etc. will be referred to as "Embodiment 1", and differences from Embodiment 1 will be mainly described. In the other embodiments below, components that may be similar to those in the above-described Embodiment 1 will be given the same reference numerals, and descriptions thereof may be omitted.

[0053] Fig. 7 is a plan view showing a portion of rotor core 32A according to embodiment 2. The portion of rotor core 32A shown in Fig. 7 is the same as the portion of rotor core 32 according to embodiment 1 shown in Fig. 3. This also applies to Figs. 8 to 10, which will be referred to later.

[0054] The rotor core 32A according to the second embodiment differs from the rotor core 32 according to the first embodiment in that the first magnet holes 321 and the permanent magnets 61 are replaced with first magnet holes 321A and permanent magnets 61A.

[0055] The first magnet hole 321A according to Example 2 differs from the first magnet hole 321 according to Example 1 in the following respects. Like the first magnet hole 321 according to Example 1, the first magnet hole 321A has a W-shape. However, unlike the first magnet hole 321 according to Example 1, the shape of the convex shape extending radially inward has a curved portion (see R71). In the example shown in FIG. 7 , the first magnet hole 321A has three portions: hole portion 321A-1 on the d-axis and hole portions 321A-2 arranged separately on both sides of the d-axis. Of these, hole portion 321A-2 has a curved portion (see R71) with a center of curvature on the d-axis side. In this case, the center line LN7 of the overall shape of the first magnet hole 321A also has a similar curved portion at a position corresponding to bridge 43A.

[0056] In this case, the radius of curvature of the curved portion (see R71) associated with hole portion 321A-2 may be smaller than the radius of curvature of the curved portion (see R41, R42) associated with second magnet hole 322. This allows the magnetic path width between first magnet hole 321A and second magnet hole 322 (i.e., magnetic path width L61A in second portion 3212A) to be approximately constant throughout.

[0057] The permanent magnet 61A according to the second embodiment may have a curved shape corresponding to the shape of the first magnet hole 321A. The permanent magnet 61A may be made of a bonded magnetic material. In the example shown in FIG. 7, the permanent magnet 61A is made of a bonded magnetic material and is tightly packed into the first magnet hole 321A, but a flux barrier (gap) may be provided.

[0058] The second embodiment also achieves the same effects as the first embodiment. That is, the magnetic path width L60A generated at the center of one side (the radially inward convex shape) of the W-shaped second magnet hole 322 relative to the d-axis can be made significantly smaller than the magnetic path width L60' of the comparative example shown in FIG. 5A. As a result, this embodiment can effectively reduce stress in each bridge 42, 44, 45 due to centrifugal force while ensuring the necessary magnetic path width (e.g., a magnetic path width equal to or greater than magnetic path width L61A) throughout the second portion 3212A. Similarly, the mass of the first portion 3211A can be reduced, effectively reducing stress in each bridge 41A, 43A due to centrifugal force.

[0059] Furthermore, according to Example 2, the first magnet hole 321A has a hole portion 321A-1 on the d-axis that has a curved portion (see R72) with a center of curvature on the radially inner side. This allows the magnetic path width on the d-axis (see magnetic path width L62A) to be reduced while still maintaining the necessary magnetic path width (e.g., a magnetic path width equal to or greater than magnetic path width L61A) compared to when the curved portion is linear. This reduces the mass of the second portion 3212A, and further effectively reduces the stress in each bridge 42, 44, 45 due to centrifugal force. Note that this effect is similar to that of Example 1 described above.

[0060] FIG. 8 is a plan view showing a portion of a rotor core 32B according to the third embodiment.

[0061] The rotor core 32B according to the third embodiment differs from the rotor core 32 according to the first embodiment in that the first magnet holes 321 and the permanent magnets 61 are replaced with first magnet holes 321B and permanent magnets 61B. The rotor core 32B according to the third embodiment also differs from the rotor core 32 according to the first embodiment in that the second magnet holes 322 and the permanent magnets 62 are replaced with second magnet holes 322B and permanent magnets 62B.

[0062] The first magnet hole 321B and the permanent magnet 61B according to the third embodiment may be similar to the first magnet hole 321A and the permanent magnet 61A according to the second embodiment described above with reference to FIG.

[0063] The second magnet hole 322B according to Example 3 differs from the second magnet hole 322 according to Example 1 in the following respects. The second magnet hole 322B differs from the second magnet hole 322 according to Example 1 in that the portion corresponding to the intermediate bridge 45 is connected, but the overall shape is similar. Therefore, the second magnet hole 322B has a similar curved portion (see R43).

[0064] The permanent magnet 62B according to the third embodiment may have a curved shape corresponding to the shape of the second magnet hole 322B. The permanent magnet 62B may be made of a bonded magnetic material. In the example shown in FIG. 8, the permanent magnet 62B is made of a bonded magnetic material and is tightly packed into the second magnet hole 322B, but a flux barrier (gap) may be provided.

[0065] In the third embodiment, the magnetic path widths L60B, L61B, and L62B can be substantially the same as the magnetic path widths L60A, L61A, and L62A according to the second embodiment shown in FIG.

[0066] The third embodiment also provides the same effects as the first and second embodiments. That is, the present embodiment can effectively reduce the stress in each of the bridges 42B and 44B caused by the centrifugal force while ensuring the necessary magnetic path width (for example, a magnetic path width equal to or greater than the magnetic path width L61B) throughout the second portion 3212B. Similarly, the mass of the first portion 3211B can be reduced, and the stress in each of the bridges 41B and 43B caused by the centrifugal force can be effectively reduced.

[0067] FIG. 9 is a plan view showing a part of a rotor core 32C according to the fourth embodiment.

[0068] The rotor core 32C according to the fourth embodiment differs from the rotor core 32 according to the first embodiment in that the first magnet holes 321 and the permanent magnets 61 are replaced with first magnet holes 321C and permanent magnets 61C. The rotor core 32C according to the fourth embodiment also differs from the rotor core 32 according to the first embodiment in that the second magnet holes 322 and the permanent magnets 62 are replaced with second magnet holes 322C and permanent magnets 62C.

[0069] First magnet hole 321C according to Example 4 differs from first magnet hole 321 according to Example 1 in the following respects. First magnet hole 321C differs from first magnet hole 321 according to Example 1 in that it is divided into two holes, one on each side of the d-axis, but has a similar overall shape. Therefore, first magnet hole 321C has a similar curved portion (see R73).

[0070] The permanent magnet 61C according to the fourth embodiment may have a curved shape corresponding to the shape of the first magnet hole 321C. The permanent magnet 61C may be made of a bonded magnetic material. In the example shown in FIG. 9, the permanent magnet 61C is made of a bonded magnetic material and is tightly packed into the first magnet hole 321C, but a flux barrier (gap) may be provided.

[0071] The second magnet hole 322C according to the fourth embodiment may be similar to the second magnet hole 322B according to the third embodiment described above with reference to FIG.

[0072] The permanent magnet 62C according to the fourth embodiment may have a curved shape corresponding to the shape of the second magnet hole 322C. The permanent magnet 62C may be made of a bonded magnetic material. In the example shown in Fig. 9, the permanent magnet 62C is made of a bonded magnetic material and is tightly packed into the second magnet hole 322C, but a flux barrier (gap) may be provided.

[0073] In the fourth embodiment, the magnetic path widths L60C, L61C, and L62C can be substantially the same as the magnetic path widths L60, L61, and L62 (see FIG. 6) in the first embodiment, respectively.

[0074] The fourth embodiment also provides the same effects as the first and second embodiments. That is, according to the present embodiment, the stress in each of the bridges 42C and 44C caused by centrifugal force can be effectively reduced while ensuring a necessary magnetic path width (for example, a magnetic path width equal to or greater than the magnetic path width L61C) throughout the second portion 3212C. Similarly, the mass of the first portion 3211C can be reduced, and the stress in each of the bridges 41C and 43C caused by centrifugal force can be effectively reduced.

[0075] 10 is a plan view showing a portion of a rotor core 32D according to Example 5. The rotor core 32D according to Example 5 differs from the rotor core 32 according to Example 1 in that the first magnet holes 321 and the permanent magnets 61 are replaced with second magnet holes 322D and permanent magnets 62D. The second magnet holes 322D and the permanent magnets 62D are similar to the second magnet holes 322B and the permanent magnets 62B according to Example 3 described above with reference to FIG.

[0076] The fifth embodiment also provides the same effects as the first embodiment.

[0077] Although each embodiment has been described in detail above, it is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of components of the above-described embodiments.

[0078] For example, in the above-described first embodiment (as well as other embodiments), the radially inward convex shape of second magnet hole 322 has a curved portion, but this is not limited to this. Only the radially inward convex shape of first magnet hole 321 may have a curved portion. Also, in the above-described first embodiment (as well as other embodiments), first magnet hole 321 includes two or more hole portions that are symmetrical about the d axis when viewed in the axial direction and are connected in the circumferential direction, but first magnet hole 321 may be formed by a single hole portion. [Explanation of symbols]

[0079] 30... rotor (rotor for rotating electrical machine), 32, 32A to D... rotor core, 328... outer circumferential surface, 3211, 3211A to C... first portion, 3212, 3212A to C... second portion, 3213... third portion, 321, 321A to C... first magnet hole, 322, 322A to D... second magnet hole, 61, 61A to C... permanent magnet (first permanent magnet), 62, 62A to D... permanent magnet (second permanent magnet), R41, R42... curved portion

Claims

1. a rotor core in which first magnet holes are formed symmetrically with respect to the d axis when viewed in the axial direction, and second magnet holes including two or more hole portions that are connected in the circumferential direction are formed symmetrically with respect to the d axis when viewed in the axial direction; a first permanent magnet disposed in the first magnet hole; a second permanent magnet disposed in the second magnet hole, the rotor core includes a first portion located radially outward of the first magnet holes and forming an outer peripheral surface of the rotor core, a second portion passing between the first magnet holes and the second magnet holes and extending on both circumferential sides to the outer peripheral surface of the rotor core, and a third portion passing radially inward of the second magnet holes and extending on both circumferential sides to the outer peripheral surface of the rotor core, the first magnet hole has a shape that is convex toward the radially inward side of the rotor core on one circumferential side with respect to the d axis, the second magnet hole has a shape that is convex toward the radially inward side of the rotor core on one circumferential side with respect to the d axis, At least one of the first magnet holes and the second magnet holes has a hole portion extending on both circumferential sides of the d axis across or passing through the d axis, which hole portion has a shape that is convex toward the radially outer side of the rotor core when viewed in the axial direction, and the shape that is convex toward the radially inner side of the rotor core has a curved portion when viewed in the axial direction, At least one of the rotors includes the second magnet hole, and the second permanent magnet has a curved shape corresponding to the curved portion.

2. 2 . The rotor for a rotating electric machine according to claim 1 , wherein at least one of the first permanent magnets further includes the first magnet hole, and the first permanent magnet has a curved shape corresponding to the curved portion.

3. 3. The rotor for a rotating electric machine according to claim 2, wherein a radius of curvature of the curved portion of the second magnet hole is larger than a radius of curvature of the curved portion of the first magnet hole.

4. a rotor core in which first magnet holes are formed symmetrically with respect to the d axis when viewed in the axial direction, and second magnet holes including two or more hole portions that are connected in the circumferential direction are formed symmetrically with respect to the d axis when viewed in the axial direction; a first permanent magnet disposed in the first magnet hole; a second permanent magnet disposed in the second magnet hole, the rotor core includes a first portion located radially outward of the first magnet holes and forming an outer peripheral surface of the rotor core, a second portion passing between the first magnet holes and the second magnet holes and extending on both circumferential sides to the outer peripheral surface of the rotor core, and a third portion passing radially inward of the second magnet holes and extending on both circumferential sides to the outer peripheral surface of the rotor core, the first magnet hole has a shape that is convex toward the radially inward side of the rotor core on one circumferential side with respect to the d axis, the second magnet hole has a shape that is convex toward the radially inward side of the rotor core on one circumferential side with respect to the d axis, At least one of the first magnet holes and the second magnet holes has a hole portion extending on both circumferential sides of the d axis across or passing through the d axis, which hole portion has a shape that is convex toward the radially outer side of the rotor core when viewed in the axial direction, and the shape that is convex toward the radially inner side of the rotor core has a curved portion when viewed in the axial direction, At least one of the rotors further includes the first magnet hole, and the first permanent magnet has a curved shape corresponding to the curved portion.

5. 5. The rotor for a rotating electric machine according to claim 1, wherein the second permanent magnet is made of a bonded magnet material.

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