Rotor for rotating electrical machine

Abstract

To provide a rotor that secures a magnetic path width with a large effect of enhancing reluctance torque, while securing good magnetizability.SOLUTION: A rotor 30 of a rotary electric machine has a plurality of magnetic poles along a circumferential direction. The rotor includes: a rotor core in which first magnet holes 321 are disposed on the radially outer side and second magnet holes 322 are disposed on the radially inner side; and a plurality of permanent magnets. The plurality of permanent magnets include: a plurality of first permanent magnets 61 disposed in the first magnet holes; and a plurality of second permanent magnets 62 which are disposed in the second magnet holes and which each have an arc shape projected toward the radially inner side when viewed in the axial direction. The second permanent magnets related to one magnetic pole include a pair of the second permanent magnets that are arranged symmetrically about a d-axis related to the one magnetic pole. One of the pair of second permanent magnets on one side in the circumferential direction has an arc center of the arc shape offset to the one side in the circumferential direction with respect to the d-axis when viewed in the axial direction. The other one of the pair of second permanent magnets on the other side in the circumferential direction has an arc center of the arc shape offset to the other side in the circumferential direction with respect to the d-axis. when viewed in the axial direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] In a rotor for a rotating electric machine in which arc-shaped permanent magnets are arranged in two layers, one on the outer diameter side and one on the inner diameter side, a technology is known in which the arc center of the outer diameter side arc magnet is located on the d axis, the arc center of the inner diameter side arc magnet on one circumferential side of the d axis is offset to the other circumferential side of the d axis, and the arc center of the inner diameter side arc magnet on the other circumferential side of the d axis is offset to one circumferential side of the d axis. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-125970 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional technique, in which the centers of the inner diameter arc magnets arranged symmetrically about the d-axis are offset to the other circumferential side and one circumferential side with respect to the d-axis, respectively, the end on the d-axis side of both circumferential ends of the inner diameter arc magnet tends to approach the inner diameter side of the rotor. In this case, it is difficult to ensure a magnetic path width that has a large effect of improving reluctance torque while ensuring good magnetization.

[0005] Therefore, in one aspect, an object of the present disclosure is to ensure good magnetization while ensuring a magnetic path width that has a large effect of improving reluctance torque. [Means for solving the problem]

[0006] According to one aspect, there is provided a rotor for a rotating electric machine having a plurality of magnetic poles along a circumferential direction, a rotor core in which a first magnet hole is formed on a radially outer side and a second magnet hole is formed on a radially inner side for each of the plurality of magnetic poles; a plurality of permanent magnets forming the plurality of magnetic poles; The plurality of permanent magnets are A plurality of first permanent magnets provided in the first magnet holes; a plurality of second permanent magnets provided in the second magnet holes and having an arc shape that is convex radially inward when viewed in the axial direction; the plurality of second permanent magnets associated with one magnetic pole include a pair of second permanent magnets arranged symmetrically with respect to a d-axis associated with the one magnetic pole, The second permanent magnet on one circumferential side of the pair of second permanent magnets has a center of an arc related to the arc shape offset to one circumferential side with respect to the d axis when viewed in the axial direction, A rotor for a rotating electric machine is provided in which the second permanent magnet on the other circumferential side of the pair of second permanent magnets has a center of an arc related to the arc shape offset toward the other circumferential side with respect to the d-axis when viewed in the axial direction. Effect of the Invention

[0007] According to one aspect, the present disclosure makes it possible to ensure a magnetic path width that has a large effect of improving reluctance torque while ensuring good magnetization. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view that shows a schematic cross-sectional structure of a motor (an example of a rotating electric machine) according to an embodiment. [Diagram 2] 2 is a cross-sectional view of a rotor (a cross-sectional view taken along a plane perpendicular to the axial direction). [Diagram 3] 3 is an enlarged view of a portion relating to one magnetic pole shown in FIG. 2. [Figure 4] FIG. 4 is an explanatory diagram conceptually showing the upper limit of the radius of the first or second permanent magnet. [Diagram 5] FIG. [Figure 6] FIG. 1 is an explanatory diagram (part 1) for comparison with a comparative example. [Figure 7] FIG. 2 is an explanatory diagram (part 2) for comparison with a comparative example. [Figure 8] FIG. 4 is an explanatory diagram of a rotor according to a first modified example. [Figure 9] FIG. 11 is an explanatory diagram of a rotor according to a second modified example. [Figure 10] FIG. 11 is an explanatory diagram of a rotor according to a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 be limiting, and 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 shows a schematic cross-sectional structure of a motor 1 (an example of a rotating electric machine) according to an 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 given to only some of the parts that exist with the same attribute.

[0011] FIG. 1 illustrates 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, unless otherwise specified below (i.e., other than the description of the outer shape of the arc-shaped permanent magnet), 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. Note that the outer shape of the arc-shaped permanent magnet is based on the arc of the permanent magnet, and for example, the radially outer side of the outer shape of the arc-shaped permanent magnet means the radially outer side related to the arc of the permanent magnet. Also, 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, for example, 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, a circular ring-shaped laminated steel plate of a magnetic material, and a plurality of slots (not shown) around which the coils 22 are wound are formed on the radial inside of the stator core 211.

[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, a first permanent magnet 61, and a second permanent magnet 62.

[0016] The rotor core 32 is fixed to a 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 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 joined to the rotor shaft 34 by key joints or spline joints. The rotor shaft 34 is rotatably supported by the motor housing 10 via bearings 14a, 14b. The rotor shaft 34 defines the rotating shaft 12 of the motor 1.

[0017] The rotor core 32 is formed, for example, from laminated steel plates of a circular magnetic material. A plurality of first permanent magnets 61 and a plurality of second permanent magnets 62 (see FIG. 2) are embedded inside the rotor core 32. That is, the rotor core 32 has a plurality of magnet holes 321, 322 (see FIG. 2) that penetrate in the axial direction, and the first permanent magnets 61 and the second permanent magnets 62 are inserted 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] 2, the rotor core 32 has a rotationally symmetric shape centered on the rotating shaft 12 when viewed in the axial direction (i.e., in an axial view). In the example shown in Fig. 2, the rotor core 32 has a shape in which the first permanent magnets 61 and the second permanent magnets 62 of each pair overlap each other every 45 degrees rotation about the rotating shaft 12.

[0019] The first permanent magnets 61 and the second permanent magnets 62 may be made of neodymium or the like. In this embodiment, as an example, as shown in FIG. 2, the first permanent magnets 61 and the second permanent magnets 62 are arranged in pairs in a substantially V-shape (a substantially V-shape with the radially outwardly open) when viewed in the axial direction. In this case, a common magnetic pole is formed between the pair of first permanent magnets 61 and between the pair of second permanent magnets 62. The first permanent magnets 61 and the second permanent magnets 62 are arranged in a manner in which S poles and N poles alternate in the circumferential direction. In this embodiment, the number of magnetic poles is eight, but the number of magnetic poles is arbitrary.

[0020] 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 may be solid.

[0021] Next, the rotor core 32, the first permanent magnet 61, and the second permanent magnet 62 will be further described with reference to Fig. 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.

[0022] FIG. 3 is an enlarged view of a portion relating to one magnetic pole shown in FIG. 2. The configuration relating to one magnetic pole is basically symmetrical with respect to the d-axis (written as "d-axis" in English in FIG. 3). In FIG. 3, the X1 side and the X2 side are defined with the d-axis as the center. FIG. 4 is an explanatory diagram conceptually showing the upper limit of the radius of the first permanent magnet 61 and the second permanent magnet 62. FIG. 4 shows a circle 402 corresponding to the outer shape of the rotor core 32, as well as a circle 400 for explaining the magnet configuration. In FIG. 4, the dotted line dividing the circle 402 into eight parts corresponds to the direction of the q-axis.

[0023] Rotor core 32 is formed with radially outer magnet hole 321 (hereinafter referred to as "first magnet hole 321") and radially inner magnet hole 322 (hereinafter referred to as "second magnet hole 322").

[0024] The first magnet holes 321 are formed in pairs symmetrically with respect to the d-axis in a generally V-shape (a generally V-shape that opens radially outward). A first permanent magnet 61 is provided in each of the first magnet holes 321. A gap may be provided between the first magnet holes 321 and the first permanent magnet 61 at both longitudinal ends of the first permanent magnet 61. This gap may be hollow or may be filled with resin or the like.

[0025] In this embodiment, the first permanent magnet 61 has an arc shape that is convex radially inward when viewed in the axial direction. The first permanent magnet 61 may be formed by cutting a ring magnet formed by hot extrusion or the like to a corresponding radial length.

[0026] The diameter φ1 of the radially outer arc of the outer shape of the first permanent magnet 61 (in Figure 3, the radius R1 of the radially inner arc of the same outer shape is shown) is preferably relatively small. For example, when the diameter of the rotor core 32 is Φ and the number of poles of the multiple magnetic poles is M (in this embodiment, "8" as an example), it may be small enough to satisfy the following relational expression. φ1<Φ×sin(π / M) Equation (1) In this case, the right-hand side corresponds to the diameter of circle 400 within a sector with radius = Φ / 2 and central angle = 2π / M, as conceptually shown in Figure 4, and which has its center on the d-axis and is tangent to the q-axis.

[0027] In this embodiment, the center of the arc shape of each of the pair of first permanent magnets 61 (center of curvature when viewed in the axial direction) is offset with respect to the d-axis. In this case, the side offset with respect to the d-axis is the side on which the corresponding first permanent magnets 61 are arranged with respect to the d-axis. That is, the center of the arc shape of the first permanent magnet 61 on the X1 side is offset to the X1 side with respect to the d-axis, and the center of the arc shape of the first permanent magnet 61 on the X2 side is offset to the X2 side with respect to the d-axis (see offset amount d1 in FIG. 3). Hereinafter, such a configuration in which the center of the arc shape of one first permanent magnet 61 is offset with respect to the d-axis to the arrangement side of the one first permanent magnet 61 is also referred to as a "configuration in which the arc centers are offset to the same side with respect to the d-axis". This also applies to the second permanent magnet 62 described later.

[0028] Such a configuration in which the arc center of the first permanent magnet 61 is offset to the same side with respect to the d-axis can be more easily realized by arranging the first permanent magnet 61 with a relatively small radius that satisfies formulas (1) and (2). This can also be seen from the fact that when the radius of circle 400 shown in Fig. 4 is reduced while maintaining a state of tangent to the q-axis on the X1 side, the center of curvature of the circle moves to the X1 side with respect to the d-axis.

[0029] The second magnet hole 322 is provided radially inward from the first magnet hole 321. The second magnet holes 322 are formed in pairs symmetrically with respect to the d axis in a substantially V-shape (a substantially V-shape that opens radially outward). A second permanent magnet 62 is provided in each of the second magnet holes 322. A gap may be provided between the second magnet hole 322 and the second permanent magnet 62 at both longitudinal ends of the second permanent magnet 62. The gap may be hollow or may be filled with resin or the like.

[0030] In this embodiment, the second permanent magnet 62 has an arc shape that is convex radially inward when viewed in the axial direction. The second permanent magnet 62 may be formed by cutting a ring magnet formed by hot extrusion molding or the like to a corresponding radial length, similar to the first permanent magnet 61. In this case, the ring magnet for forming the second permanent magnet 62 may be the same as the ring magnet for forming the first permanent magnet 61. That is, the first permanent magnet 61 and the second permanent magnet 62 may have the same annular shape and the same width dimension (see t1 and t2 in FIG. 3). In this case, productivity can be increased by sharing the ring magnet.

[0031] The diameter φ2 of the radially outer arc of the outer shape of the second permanent magnet 62 (in FIG. 3, the radius R2 of the radially inner arc of the same outer shape is shown) preferably satisfies the following relational expression, where Φ is the diameter of the rotor core 32 and M is the number of poles of the multiple magnetic poles: φ2<Φ×sin(π / M) Equation (2) It should be noted that formula (2) has the same relationship as formula (1) described above.

[0032] In this embodiment, the pair of second permanent magnets 62 have a configuration in which the arc centers are offset to the same side with respect to the d-axis, similar to the pair of first permanent magnets 61 described above. That is, the center of the arc shape of the second permanent magnet 62 on the X1 side is offset to the X1 side with respect to the d-axis, and the center of the arc shape of the second permanent magnet 62 on the X2 side is offset to the X2 side with respect to the d-axis (see offset amount d2 in FIG. 3). Note that, in the example shown in FIG. 3, the offset amount d2 of the pair of second permanent magnets 62 is slightly smaller than the offset amount d1 of the pair of first permanent magnets 61, but may be the same or slightly larger than the offset amount d1.

[0033] 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 bridge portions.

[0034] Specifically, the first portion 3211 extends radially outward from the first magnet hole 321. The first portion 3211 forms a part 328A of the outer circumferential surface 328 of the rotor core 32.

[0035] The second portion 3212 passes between the second magnet hole 322 and the first magnet hole 321 in the radial direction, and extends to the outer circumferential surface 328 of the rotor core 32 on both circumferential sides. The second portion 3212 forms a part 328B of the outer circumferential surface 328 of the rotor core 32 on both circumferential sides of the first portion 3211 (hereinafter, also referred to as "outer circumferential surface portion 328B of the second portion 3212"). The second portion 3212 forms a magnetic path of the q-axis magnetic flux. Specifically, the q-axis magnetic flux flows between the second magnet hole 322 and the first magnet hole 321 from one end (the outer circumferential surface portion 328B on one side) of the second portion 3212 to the other end (the outer circumferential surface portion 328B on the other side).

[0036] In this embodiment, the width of the second portion 3212 in the direction intersecting the magnetic path gradually increases from the outer peripheral surface portion 328B toward the d-axis. For example, as shown in FIG. 3, the same width L2 at the radially inner end portion (the end portion closer to the d-axis in the circumferential direction) of the first permanent magnet 61 and the second permanent magnet 62 is larger than the same width L1 at the radially outer end portion (the end portion farther from the d-axis in the circumferential direction) of the first permanent magnet 61 and the second permanent magnet 62. Such a feature of the width of the second portion 3212 is facilitated by realizing a configuration in which the arc centers of the first permanent magnet 61 and the second permanent magnet 62 are offset to the same side with respect to the d-axis. That is, by realizing a configuration in which the arc centers of the first permanent magnet 61 and the second permanent magnet 62 are offset to the same side with respect to the d-axis, it becomes easy to configure the width of the second portion 3212 to be gradually increased from the outer peripheral surface portion 328B toward the d-axis. This makes it easy to realize a magnetic path width that has a large effect of improving reluctance torque.

[0037] Third portion 3213 passes radially inward from second magnet hole 322 and extends on both circumferential sides to outer circumferential surface 328 of rotor core 32. Third portion 3213 forms part 328C of outer circumferential surface 328 of rotor core 32 on both circumferential sides of second portion 3212.

[0038] Furthermore, the rotor core 32 has the three portions 3211, 3212, and 3213, and thus has a plurality of bridge portions 41, 42, 43, and 44 connecting the three portions 3211, 3212, and 3213.

[0039] The bridge portion 41 (hereinafter referred to as the "first bridge portion 41") supports the first portion 3211 on the radially outer side with respect to the second portion 3212. The first bridge portions 41 are provided in pairs on both circumferential sides of the first portion 3211. The first bridge portions 41 extend between the outer circumferential surface 328 of the rotor core 32 and the first magnet hole 321.

[0040] The bridge portion 42 (hereinafter referred to as the "second bridge portion 42") supports the second portion 3212 on the radially outer side with respect to the third portion 3213. The second bridge portions 42 are provided in pairs on both circumferential sides of the second portion 3212. The second bridge portions 42 extend between the outer circumferential surface 328 of the rotor core 32 and the second magnet hole 322.

[0041] The bridge portion 43 (hereinafter referred to as the "first center bridge portion 43") supports the first portion 3211 relative to the second portion 3212 on the d axis.

[0042] The bridge portion 44 (hereinafter referred to as the "second center bridge portion 44") supports the second portion 3212 with respect to the third portion 3213 on the d axis.

[0043] Next, further effects of the rotor 30 of this embodiment will be described with reference to Fig. 5 to Fig. 7. Fig. 5 is an explanatory diagram of magnetization, and Figs. 6 and 7 are explanatory diagrams of effects related to the radius and arrangement of the arc shapes of the first permanent magnets 61 and the second permanent magnets 62. In Fig. 5, in a top view of the rotor core 32 on which the first permanent magnets 61 and the second permanent magnets 62 are provided, the flow of magnetic flux for magnetizing the first permanent magnets 61 and the second permanent magnets 62 (hereinafter referred to as "magnetizing magnetic flux") is diagrammatically shown by arrows R500.

[0044] According to this embodiment, as described above, by realizing a configuration in which the arc centers of the first permanent magnet 61 and the second permanent magnet 62 are offset to the same side with respect to the d-axis, not only can the above-mentioned favorable magnetic path width be realized, but the first permanent magnet 61 and the second permanent magnet 62 can be arranged in a position where the magnetizing magnetic flux can easily flow, as shown in Fig. 5. This makes it possible to realize favorable output characteristics (torque characteristics) of the motor 1.

[0045] In Fig. 6, as a comparative example, the outlines of the first permanent magnet 61' and the second permanent magnet 62' in the case where the radius of the arc shape is relatively large are shown by dotted lines. In this case, as shown in Fig. 6, the width L of the second portion 3212 is smaller than that shown by the solid line. In other words, it becomes difficult to realize a magnetic path width (magnetic path width in the second portion 3212) that has a large effect of improving the reluctance torque.

[0046] On the other hand, in the comparative example shown in Fig. 7, unlike the comparative example shown in Fig. 6, the second permanent magnet 62' having a relatively large radius of the arc shape is used to make the width L of the second portion 3212 relatively large, and the arrangement angle of the second permanent magnet 62' is changed in the direction in which the width on the side closer to the d-axis increases, as shown by the dotted line in Fig. 7. In this case, although a magnetic path width with a large effect of improving reluctance torque can be realized, the position of the second permanent magnet 62' is likely to be shifted from a position where the magnetizing magnetic flux can easily flow, which may result in a decrease in magnetization. In Fig. 7, the arc 700 is an arc that passes through the innermost radial position of the second permanent magnet 62, and the arc 702 is an arc that passes through the innermost radial position of the second permanent magnet 62'.

[0047] In this regard, according to this embodiment, as described above, by arranging the first permanent magnet 61 and the second permanent magnet 62 with a relatively small radius so as to satisfy the formulas (1) and (2), it is possible to realize a magnetic path width that has a large effect of improving the reluctance torque while ensuring good magnetization.

[0048] In this embodiment, the first permanent magnet 61 has the same arc shape as the second permanent magnet 62 as a preferred example, but is not limited to this. For example, the first permanent magnet 61 may have an arc shape with a larger radius than the second permanent magnet 62, and may ultimately be in a linear form.

[0049] Next, further effects of this embodiment will be described along with various modified examples with reference to Fig. 8 onwards. In Fig. 8 onwards, components that may be similar to those in the above-mentioned embodiment will be given the same reference numerals and descriptions thereof will be omitted in some cases.

[0050] FIG. 8 is an explanatory diagram of a rotor 30A according to a first modified example, and is an enlarged plan view of the configuration relating to one magnetic pole as viewed in the axial direction, similar to FIG. 3 described above.

[0051] A rotor 30A according to the first modified example differs from the rotor 30 according to the above-described embodiment in that the rotor core 32 is replaced with a rotor core 32A, and the first permanent magnet 61 is replaced with a first permanent magnet 61A.

[0052] Rotor core 32A differs from rotor core 32 of the above-described embodiment in that first magnet hole 321 is replaced with first magnet hole 321A. Only one first magnet hole 321A is provided for one magnetic pole, as shown in Fig. 8. Accordingly, first center bridge portion 43 is omitted, and therefore first bridge portion 41A has a radial thickness greater than that of first bridge portion 41.

[0053] The first permanent magnet 61A differs from the first permanent magnet 61 of the above embodiment in that only one first permanent magnet 61A is provided for one magnetic pole. In this case, the first permanent magnet 61A may have an arc shape similar to the first permanent magnet 61 of the above embodiment. The center of the arc shape of the first permanent magnet 61A is located on the d-axis.

[0054] According to the first modified example, by having the second permanent magnet 62 similar to that of the above-described embodiment, it is possible to realize a magnetic path width that has a large effect of improving the reluctance torque.

[0055] In the first modified example, since the first center bridge portion 43 is omitted, the first bridge portion 41A supporting the centrifugal force related to the first permanent magnet 61A has a larger radial thickness than the first bridge portion 41. The first bridge portion 41A having a large radial thickness is disadvantageous in that it increases leakage flux. In other words, according to the above-mentioned embodiment, a configuration can be realized in which the arc center of the first permanent magnet 61 is offset to the same side with respect to the d-axis while using the first permanent magnet 61 having a relatively small radius. As a result, according to the above-mentioned embodiment, the radial thickness of the first bridge portion 41 can be made relatively small by the first center bridge portion 43, and as a result, leakage flux can be reduced.

[0056] FIG. 9 is an explanatory diagram of a rotor 30B according to a second modified example, and is an enlarged plan view of the configuration related to one magnetic pole as viewed in the axial direction, similar to FIG. 3 described above.

[0057] The rotor 30B according to the second modified example differs from the rotor 30 according to the above-described embodiment in that the second permanent magnet 62 is replaced with a second permanent magnet 62B.

[0058] As shown in FIG. 9, the second permanent magnet 62B is different from the second permanent magnet 62 of the above embodiment in that two second permanent magnets 62B are arranged for each second magnet hole 322. In this case, the second permanent magnet 62B may have the same configuration as the first permanent magnet 61, including the circumferential length. That is, the first permanent magnet 61 and the second permanent magnet 62B may be formed from a common magnet piece. In this case, the first permanent magnet 61 and the second permanent magnet 62B can be manufactured without distinguishing between them, so that productivity can be improved. In addition, by arranging two second permanent magnets 62B for each second magnet hole 322, it is possible to ensure the required amount of magnets as the whole second permanent magnet while maintaining high productivity. In addition, in order to increase the yield, the common magnet piece may have a circumferential length that is divisible by an integer with respect to the circumferential length (length of the circumference) of the circular ring magnet before cutting.

[0059] According to the second modified example, similarly to the above-mentioned embodiment, it is possible to realize a magnetic path width that has a large effect of improving reluctance torque while ensuring good magnetization.

[0060] In the second modified example, two identical second permanent magnets 62B are provided for one second magnet hole 322, but three or more second permanent magnets 62B may be provided for one second magnet hole 322. Furthermore, two or more identical first permanent magnets 61 may be provided for one first magnet hole 321.

[0061] Furthermore, in the second modified example, as shown in FIG. 9, the two second permanent magnets 62B provided in one second magnet hole 322 are adjacent to each other in the circumferential direction, but may be slightly spaced apart in the circumferential direction.

[0062] FIG. 10 is an explanatory diagram of a rotor 30C according to a third modified example, and is an enlarged plan view of the configuration related to one magnetic pole as viewed in the axial direction, similar to FIG. 3 described above.

[0063] A rotor 30C according to the third modified example differs from the rotor 30 according to the above-described embodiment in that the rotor core 32 is replaced with a rotor core 32C, and the second permanent magnet 62 is replaced with a second permanent magnet 62C.

[0064] The rotor core 32C differs from the rotor core 32 of the above-described embodiment in that the second magnet holes 322 are replaced with second magnet holes 322C. As shown in Fig. 10, three second magnet holes 322C are provided for one magnetic pole. Accordingly, the second center bridge portion 44 is replaced with two second center bridge portions 44C.

[0065] The second permanent magnet 62C is different from the second permanent magnet 62 of the above-mentioned embodiment in that three second permanent magnets are provided for one magnetic pole. That is, the second permanent magnet 62C includes a second permanent magnet 621C on the X1 side of the d-axis, a second permanent magnet 622C on the X2 side of the d-axis, and a second permanent magnet 623C in the center. The second permanent magnets 621C and 622C may have the same shape and arrangement as the pair of second permanent magnets 62 of the above-mentioned embodiment. However, in the example shown in FIG. 10, the second permanent magnets 621C and 622C are different from the pair of second permanent magnets 62 of the above-mentioned embodiment only in the circumferential length. In this case, the second permanent magnets 621C and 622C may have the same configuration as the first permanent magnet 61, including the circumferential length.

[0066] The central second permanent magnet 623C may have an arc shape that is convex radially inward when viewed in the axial direction. The center of the arc shape of the central second permanent magnet 623C is located on the d-axis.

[0067] According to the second modified example, the second permanent magnet 62C associated with one magnetic pole includes a pair of second permanent magnets 621C, 622C arranged symmetrically with respect to the d-axis associated with one magnetic pole, and the pair of second permanent magnets 621C, 622C has a configuration similar to that of the pair of second permanent magnets 62 in the above-described embodiment, so that the same effect as in the above-described embodiment can be obtained. That is, by gradually increasing the width of the second portion 3212 from the outer circumferential surface portion 328B toward the d-axis, a magnetic path width having a large effect of improving reluctance torque can be realized.

[0068] Although each embodiment has been described above in detail, 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 the components of the above-mentioned embodiments. Furthermore, among the effects of each embodiment, the effects related to the dependent claims are additional effects that are distinguished from the generic concept (independent claim).

[0069] For example, in the above-described embodiment, as a preferred example, a configuration is realized in which the arc centers of both the first permanent magnet 61 and the second permanent magnet 62 are offset to the same side with respect to the d axis, but a configuration in which the arc center of only the second permanent magnet 62 is offset to the same side with respect to the d axis may also be realized.

[0070] In addition, in the above-described embodiment, a two-layer arrangement is used with the first permanent magnet 61 and the second permanent magnet 62, but the present invention may also be applied to an arrangement of three or more layers in which an additional permanent magnet is arranged radially inward from the second permanent magnet 62. [Explanation of symbols]

[0071] REFERENCE SIGNS LIST 1... motor (rotating electric machine), 30, 30A, 30B, 30C... rotor, 32, 32A, 32C... rotor core, 321, 321A... first magnet hole, 322, 322C... second magnet hole, 328... outer circumferential surface, 61, 61A... first permanent magnet, 62, 62B, 62C... second permanent magnet

Claims

1. A rotor for a rotating electric machine having a plurality of magnetic poles along a circumferential direction, a rotor core in which a first magnet hole is formed on a radially outer side and a second magnet hole is formed on a radially inner side for each of the plurality of magnetic poles; a plurality of permanent magnets forming the plurality of magnetic poles; The plurality of permanent magnets are A plurality of first permanent magnets provided in the first magnet holes; a plurality of second permanent magnets provided in the second magnet holes and having an arc shape that is convex radially inward when viewed in the axial direction; the plurality of second permanent magnets associated with one magnetic pole include a pair of second permanent magnets arranged symmetrically with respect to a d-axis associated with the one magnetic pole, The second permanent magnet on one circumferential side of the pair of second permanent magnets has a center of an arc related to the arc shape offset toward the one circumferential side with respect to the d axis when viewed in the axial direction, the second permanent magnet on the other circumferential side of the pair of second permanent magnets has a center of an arc related to the arc shape offset toward the other circumferential side with respect to the d axis as viewed in the axial direction, A diameter φ 2 of the radially outer arc of the outer shape of the pair of second permanent magnets satisfies the following relational expression, where Φ is the diameter of the rotor core and M is the number of poles of the multiple magnetic poles: φ 2 < Φ×sin (π / M) , rotors for rotating electric machines.

2. The first permanent magnets each have an arc shape that is convex radially inward when viewed in the axial direction, the plurality of first permanent magnets associated with the one magnetic pole include a pair of first permanent magnets arranged symmetrically with respect to the d axis and in separate first magnet holes spaced apart by a bridge portion passing through the d axis, The first permanent magnet on one circumferential side of the pair of first permanent magnets has a center of an arc related to the arc shape offset toward the one circumferential side with respect to the d axis when viewed in the axial direction, 2. The rotor for a rotating electric machine according to claim 1, wherein the first permanent magnet on the other circumferential side of the pair of first permanent magnets has a center of an arc related to the arc shape offset toward the other circumferential side with respect to the d-axis when viewed in the axial direction.

3. The plurality of first permanent magnets and the plurality of second permanent magnets are formed by a common magnet piece, 3. The rotor for a rotating electric machine according to claim 1, wherein two or more of the common magnet pieces are arranged in one of the second magnet holes.

4. A rotor for a rotating electric machine as described in any one of claims 1 to 3, wherein the width between the first magnet hole and the second magnet hole relating to the one magnetic pole when viewed in the axial direction, which width in a direction intersecting the magnetic path, gradually increases from the outer peripheral surface of the rotor core toward the d axis.

Images