Rotating electric machine

Abstract

To raise the maximum torque while securing strength of a rotor.SOLUTION: A rotor of a rotary electric machine is provided with: magnet housing holes 311, 314 extending inside and outside in a radial direction to be orthogonal with a magnetic pole center line CL1; and magnet housing holes 312, 313, 315, 316 provided on both sides in a circumferential direction of the magnet housing holes 311, 314 and extending by inclining to the magnetic pole center line CL1 to go outside in the radial direction as separating from the magnetic pole center line CL1, and permanent magnets 411 to 416 are housed in the magnet housing holes 311 to 316. An angle θ1 formed by an extension line L21 extending in a thickness direction from the center in a width direction of the permanent magnets 412, 413 and the magnetic pole center line CL1 is larger than an angle θ2 formed by an extension line L22 extending in the thickness direction from the center in the width direction of the permanent magnets 415, 416 and the magnetic pole center line CL1.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a rotating electrical machine having a rotor in which permanent magnets are embedded.

Background Art

[0002] Conventionally, a rotating electrical machine configured by arranging a plurality of magnets on the inner peripheral side and the outer peripheral side of a plurality of magnetic pole portions in the circumferential direction of a rotor is known (see, for example, Patent Document 1). In the rotating electrical machine described in Patent Document 1, a plurality of magnet loading portions are provided in a substantially V shape symmetrically with respect to the magnetic pole center on both sides of the magnetic pole center in a plurality of magnetic pole portions in the circumferential direction of the rotor, and magnets are arranged in each of the plurality of magnet loading portions.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When magnet loading portions are provided on both sides of the magnetic pole center of the rotor as in the rotating electrical machine described in Patent Document 1 above, in order to ensure sufficient strength of the rotor, it is necessary to increase the length between a pair of magnet loading portions on both sides of the magnetic pole center of the rotor. However, when the length between a pair of magnet loading portions is increased, leakage magnetic flux increases, leading to a decrease in the maximum torque of the rotor.

Means for Solving the Problems

[0005] A rotating electric machine according to one aspect of the present invention comprises a rotor that rotates about a rotation axis, and a stator arranged around the outer surface of the rotor and generating a rotating magnetic field relative to the rotor. The rotor has a rotor core provided with magnet housing holes extending in the axial direction, and permanent magnets housed in the magnet housing holes, and is composed of a plurality of circumferentially oriented magnetic pole sections, the magnet housing holes include a plurality of magnet housing holes provided symmetrically with respect to a magnetic pole centerline extending radially from the axis of rotation in each of the plurality of circumferentially oriented magnetic pole sections, the plurality of magnet housing holes include an inner central housing hole and an outer central housing hole extending radially inward and radially outward, respectively, perpendicular to the magnetic pole centerline, a pair of inner inclined housing holes provided on both sides of the inner central housing hole in the circumferential direction and extending inclined with respect to the magnetic pole centerline so as they move away from the magnetic pole centerline, and a pair of outer inclined housing holes provided on both sides of the outer central housing hole in the circumferential direction and extending inclined with respect to the magnetic pole centerline so as they move away from the magnetic pole centerline, the permanent magnets housed in the plurality of magnet housing holes, and have a longitudinal width and a short-width The rotor core includes a plurality of permanent magnets, each comprising an inner central permanent magnet housed in an inner central housing hole, a pair of inner inclined permanent magnets housed in a pair of inner inclined housing holes, an outer central permanent magnet housed in an outer central housing hole and positioned radially to the outermost edge on the pole centerline, and a pair of outer inclined permanent magnets housed in a pair of outer inclined housing holes, the rotor core having an inner rib provided between the inner central housing hole and the inner inclined housing hole, and an outer rib provided between the outer central housing hole and the outer inclined housing hole, wherein the width of the inner rib, which is the distance between the inner central housing hole and the inner inclined housing hole, is wider than the width of the outer rib, which is the distance between the outer central housing hole and the outer inclined housing hole, and the angle between the first axis extending in the thickness direction from the widthwise center of the inner inclined permanent magnet and the pole centerline is greater than the angle between the second axis extending in the thickness direction from the widthwise center of the outer inclined permanent magnet and the pole centerline. The inner ribs extend between the inner central housing hole and the inner inclined housing hole along a third reference line toward the magnetic pole centerline, and the outer ribs extend between the outer central housing hole and the outer inclined housing hole along a fourth reference line toward the magnetic pole centerline. The angle between the third reference line and the magnetic pole centerline is greater than the angle between the fourth reference line and the magnetic pole centerline, and the fourth reference line intersects the magnetic pole centerline radially outward on the outer circumferential surface of the rotor core without intersecting the magnet housing hole radially outward on the outer rib. [Effects of the Invention]

[0006] According to the present invention, it is possible to increase the maximum torque of the rotor while ensuring sufficient strength of the rotor. [Brief explanation of the drawing]

[0007] [Figure 1] A cross-sectional view perpendicular to the axis showing the main components of a rotating electric machine according to an embodiment of the present invention. [Figure 2] A magnified view of the main part of Figure 1, showing the configuration of the rotor's magnetic pole section. [Figure 3] Figure 2 shows an example for reference. [Figure 4] A contour map showing an example of the stress analysis results for this embodiment and reference example near the inner rib of the magnetic pole section. [Figure 5] A schematic diagram showing the main directions of forces acting on the magnetic poles. [Figure 6] Enlarged view of the vicinity of the inner rib in Figure 2. [Figure 7] A contour map showing an example of stress analysis results for this embodiment and other reference examples near the inner ribs of the magnetic pole section. [Figure 8] This figure shows a modified version of Figure 2. [Figure 9] Figure 2 shows another variation of Figure 2. [Figure 10] Figure 2 shows another example for reference. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to Figures 1 to 10. The rotating electric machine according to the embodiment of the present invention can be mounted on hybrid vehicles and electric vehicles and used as an electric motor for vehicle propulsion, and can also be used as a generator. The rotating electric machine can also be mounted on vehicles and used for various purposes.

[0009] Figure 1 is a cross-sectional view perpendicular to the axis CL0, showing the main components of a rotating electric machine according to an embodiment of the present invention. Hereinafter, the direction in which the axis CL0 extends is defined as the axial direction, the direction extending radially from the axis CL0 is defined as the radial direction, and the direction along a circle centered on the axis CL0 is defined as the circumferential direction. As shown in Figure 1, the rotating electric machine 100 comprises a rotor 1 that rotates around the axis CL0 and a stator 2 arranged to surround the outer circumferential surface 1a of the rotor 1. A gap of a predetermined length is provided around the entire circumference between the outer circumferential surface 1a of the rotor 1 and the inner circumferential surface of the stator 2.

[0010] The rotor 1 has a substantially annular rotor core 10 centered on the axis CL0, and a plurality of circumferentially oriented magnetic pole portions 30 formed on the rotor core 10. For example, a rotor shaft 101, which constitutes the output shaft of a rotating electric machine 100, is fitted to the inner circumferential surface 10a of the rotor core 10, and the rotor 1 rotates integrally with the rotor shaft 101. The outer circumferential surface 1a of the rotor 1 corresponds to the outer circumferential surface of the rotor core 10. The rotor core 10 is formed by stacking a plurality of magnetic metal electromagnetic steel sheets in the axial direction.

[0011] Multiple magnetic pole sections 30 are provided at equal intervals in the circumferential direction. In the example shown in Figure 1, six magnetic pole sections 30 are provided at 60° intervals. Each magnetic pole section 30 has multiple (six in the figure) magnet housing holes 31 formed in the rotor core 10, and multiple permanent magnets 41 housed in the multiple magnet housing holes 31. Figure 1 shows a magnetic pole centerline CL1 extending radially from the axis CL0 through the circumferential center of the magnetic pole section 30. The magnetic pole centerline CL1 corresponds to the d-axis of the magnetic pole section 30 (the direction of the main magnetic flux of the permanent magnets 41). The magnetic pole centerline CL1 is set for each of the multiple magnetic pole sections 30. The boundary between the multiple magnetic pole sections 30 corresponds to the q-axis, which is electrically and magnetically perpendicular to the d-axis.

[0012] The stator 2 has a substantially annular stator core 20 centered on the axis CL0, which is arranged radially at predetermined intervals from the outer circumferential surface 1a of the rotor 1, and a coil 21 attached to the stator core 20. The stator core 20 is constructed by laminating multiple sheets of magnetic metal electromagnetic steel. Although some are not shown in the illustration, multiple teeth 22 are provided projecting radially inward from the inner circumferential surface of the stator core 20 along its entire circumference. Slots are formed between adjacent teeth 22 in the circumferential direction. The coil 21 is constructed, for example, by windings wound around the teeth 22.

[0013] When current is passed through coil 21, a magnetic field is generated in stator 2. This magnetic field interacts with the magnetic field generated by the permanent magnets 41 in the magnetic pole portion 30 of rotor 1, causing rotor 1 to rotate. Specifically, rotor 1 rotates due to magnetic torque and reluctance torque.

[0014] Figure 2 is an enlarged view of the main part of Figure 1, showing the configuration of a single magnetic pole section 30. As shown in Figure 2, the magnetic pole section 30 is provided with a plurality of magnet housing holes 31 that penetrate the rotor core 10 in the axial direction. The plurality of magnet housing holes 31 include three magnet housing holes provided on the inner circumference side (referred to as inner magnet housing holes) and three magnet housing holes provided on the outer circumference side (referred to as outer magnet housing holes). These plurality of magnet housing holes 31 have a substantially rectangular shape in cross-section perpendicular to the axis CL0 and are provided symmetrically with respect to the magnetic pole center line CL1.

[0015] More specifically, the inner magnet accommodation holes include a first magnet accommodation hole (inner central accommodation hole) 311 disposed on the magnetic pole center line CL1, and second and third magnet accommodation holes 312 and 313 (a pair of inner inclined accommodation holes) disposed on both circumferential sides of the first magnet accommodation hole 311. The first magnet accommodation hole 311 extends in the circumferential direction so as to be orthogonal to the magnetic pole center line CL1. The second and third magnet accommodation holes 312 and 313 extend while being inclined with respect to the magnetic pole center line CL1 so as to face radially outward as they move away from the magnetic pole center line CL1. Hereinafter, the first, second, and third magnet accommodation holes 311, 312, and 313 may be represented as inner magnet accommodation holes 311 to 313.

[0016] The outer magnet accommodation holes include a fourth magnet accommodation hole (outer central accommodation hole) 314 disposed on the magnetic pole center line CL1, and fifth and sixth magnet accommodation holes 315 and 316 (a pair of outer inclined accommodation holes) disposed on both circumferential sides of the fourth magnet accommodation hole 314. The fourth magnet accommodation hole 314 extends in the circumferential direction so as to be orthogonal to the magnetic pole center line CL1. The fifth and sixth magnet accommodation holes 315 and 316 extend while being inclined with respect to the magnetic pole center line CL1 so as to face radially outward as they move away from the magnetic pole center line CL1. Hereinafter, the fourth, fifth, and sixth magnet accommodation holes 314, 315, and 316 may be represented as outer magnet accommodation holes 314 to 316.

[0017] The outer magnet accommodation holes 314 to 316 are each located radially outside the inner magnet accommodation holes 311 to 313. In a cross-section perpendicular to the axis CL0, the longitudinal direction of each magnet accommodation hole 31 is referred to as the width, and the short-side direction is referred to as the height. The heights of the magnet accommodation holes 311 to 316 are the same as or approximately the same as each other. The widths of the inner magnet accommodation holes 311 to 313 are the same as or approximately the same as each other. The widths of the outer magnet accommodation holes 314 to 316 are the same as or approximately the same as each other. The widths of the inner magnet accommodation holes 311 to 313 are longer than the widths of the outer magnet accommodation holes 314 to 316.

[0018] The permanent magnet 41 includes a first permanent magnet 411 accommodated in the first magnet accommodation hole 311, a second permanent magnet 412 accommodated in the second magnet accommodation hole 312, a third permanent magnet 413 accommodated in the third magnet accommodation hole 313, a fourth permanent magnet 414 accommodated in the fourth magnet accommodation hole 314, a fifth permanent magnet 415 accommodated in the fifth magnet accommodation hole 315, and a sixth permanent magnet 416 accommodated in the sixth magnet accommodation hole 316. Various types of permanent magnets 41 can be used, such as neodymium magnets and ferrite magnets.

[0019] The first permanent magnet 411, the second permanent magnet 412, and the third permanent magnet 413 may be represented as inner permanent magnets 411 to 413, and the fourth permanent magnet 414, the fifth permanent magnet 415, and the sixth permanent magnet 416 may be represented as outer permanent magnets 414 to 416. The inner permanent magnets 411 to 413 have the same or substantially the same shape as each other. The outer permanent magnets 414 to 416 have the same or substantially the same shape as each other.

[0020] When viewed from the front along the axis CL0, the plurality of permanent magnets 41 exhibit a substantially rectangular shape corresponding to the magnet accommodation holes 31 and are formed in an axially elongated flat plate shape. In a cross-section perpendicular to the axis CL0, the longitudinal direction of each permanent magnet 41 is referred to as the width, and the short-side direction is referred to as the thickness. The width of the inner permanent magnets 411 to 413 is longer than the width of the outer permanent magnets 414 to 416. The thickness of the inner permanent magnets 411 to 413 is equal to or substantially equal to the thickness of the outer permanent magnets 414 to 416. Note that the thickness of the inner permanent magnets 411 to 413 may be thicker than the thickness of the outer permanent magnets 414 to 416.

[0021] The permanent magnet 41 is configured symmetrically with respect to the center line CL2 extending in the thickness direction through the center of the width direction thereof. Note that the center line CL2 of the first permanent magnet 411 coincides with the center line CL1 of the magnetic poles. The plurality of permanent magnets 41 are magnetized in the thickness direction. For example, the end faces in the thickness direction on the outer side in the radial direction of the plurality of permanent magnets 41 are magnetized to the N pole, and the end faces in the thickness direction on the inner side in the radial direction are magnetized to the S pole. Note that in the circumferentially adjacent magnetic pole portions 30, the magnetization directions are opposite.

[0022] Flux barriers 33 are formed in the rotor core 10, connected to the magnet housing holes 31. The flux barriers 33 are adjacent to a pair of end faces 41a and 41b at both ends in the width direction of the permanent magnet 41 and extend outward in the width direction of the permanent magnet 32. Furthermore, the radial length (length in a direction approximately perpendicular to the thickness direction of the permanent magnet 41) of some of the flux barriers 33, particularly those adjacent to the end faces 41a and 41b of the first permanent magnet 411, the flux barrier 33 adjacent to the end face 41b on the pole center side of the second permanent magnet 412, and the flux barrier 33 adjacent to the end face 41a on the pole center side of the third permanent magnet 413, is longer than the thickness of the permanent magnet 41.

[0023] The flux barrier 33 is an air layer and has greater magnetic resistance than the rotor core 10. By providing the flux barrier 33, it is possible to suppress the magnetic short circuit on the rotor side caused by the magnetic flux generated by the permanent magnet 41. The flux barrier 33 can also be filled with a resin that has a lower magnetic permeability than the rotor core 10, making the flux barrier 33 a resin layer.

[0024] Ribs 35 (referred to as inner ribs) are provided in the rotor core 10 between the first magnet housing hole 311, the second magnet housing hole 312, and the third magnet housing hole 313. More specifically, inner ribs 35 are provided between the flux barrier 33 adjacent to the first magnet housing hole 311 and the flux barrier 33 adjacent to the second magnet housing hole 312, and between the flux barrier 33 adjacent to the first magnet housing hole 311 and the flux barrier 33 adjacent to the third magnet housing hole 313. In addition, ribs are provided between the flux barrier 33 adjacent to the second magnet housing hole 312 and the outer circumferential surface 1a of the rotor core 10, and between the flux barrier 33 adjacent to the third magnet housing hole 313 and the outer circumferential surface 1a of the rotor core 10.

[0025] Furthermore, the rotor core 10 is provided with ribs 36 (referred to as outer ribs) between the fourth magnet housing hole 314, the fifth magnet housing hole 315, and the sixth magnet housing hole 316. More specifically, outer ribs 36 are provided between the flux barrier 33 adjacent to the fourth magnet housing hole 314 and the flux barrier 33 adjacent to the fifth magnet housing hole 315, and between the flux barrier 33 adjacent to the fourth magnet housing hole 314 and the flux barrier 33 adjacent to the sixth magnet housing hole 316. In addition, ribs are provided between the flux barrier 33 adjacent to the fifth magnet housing hole 315 and the outer circumferential surface 1a of the rotor core 10, and between the flux barrier 33 adjacent to the sixth magnet housing hole 316 and the outer circumferential surface 1a of the rotor core 10.

[0026] The inner rib 35 extends approximately radially with a constant or nearly constant width, which is the distance between adjacent pairs of flux barriers 33, 33. More precisely, it extends diagonally toward the magnetic pole centerline CL1. The outer rib 36 also extends approximately radially with a constant or nearly constant width. The width of the inner rib 35 is wider than the width of the outer rib 36.

[0027] Figure 3 shows an example of a magnetic pole section 30A as a reference example of this embodiment. In this reference example, there are no magnet housing holes on the magnetic pole centerline CL1, and magnet housing holes 31A are provided on both the inner and outer circumference sides of the rotor core 10A, respectively, in the circumferential direction of the magnetic pole centerline CL1. Permanent magnets 41A are housed in the magnet housing holes 31A. Ribs (center ribs) 35A and 36A are provided on the rotor core 10A along the magnetic pole centerline CL1. When the rotor 1 is rotated at a high speed in this configuration (for example, when the rotational speed of the rotor 1 is 20,000 rpm or higher), the center ribs 35A and 36A need to be thicker than those in Figure 3 in order to ensure sufficient strength of the rotor core 10A against centrifugal force. As a result, leakage flux increases, leading to a decrease in the performance of the rotating electric machine. In order to suppress the decrease in the performance of the rotating electric machine, it is necessary to increase the amount of magnets.

[0028] In contrast, in this embodiment, as shown in Figure 2, magnet housing holes 31 are provided on the magnetic pole centerline CL1 of the rotor core 10, and magnet housing holes 31 are also provided on both sides of the central magnet housing hole 31 in the circumferential direction via inner ribs 35 and outer ribs 36. As a result, multiple inner ribs 35 and outer ribs 36 are provided on the inner diameter side and outer diameter side of the rotor core 10, respectively, so the overall cross-sectional area of ​​the inner ribs 35 and outer ribs 36 is increased compared to the case where a single center rib 35A, 36A is provided. Consequently, when the rotor 1 is rotated at high speed, the thickness of the ribs 35 and 36 can be reduced compared to the case where a center rib 35A, 36A is provided. This makes it possible to ensure sufficient strength of the rotor core 10 while suppressing performance degradation.

[0029] Figure 2 shows the angle θ1 between the extension line L21 of the centerlines CL2 of the second permanent magnet 412 and the third permanent magnet 413 (for convenience, only the extension line L21 of the second permanent magnet 412 is shown) and the magnetic pole centerline CL1. Also, the angle θ2 is shown between the extension line L22 of the centerlines CL2 of the fifth permanent magnet 415 and the sixth permanent magnet 416 (for convenience, only the extension line CL22 of the fifth permanent magnet 415 is shown) and the magnetic pole centerline CL1. The extension line L21 corresponds to the direction of the main magnetic flux of permanent magnets 412 and 413, and the extension line L22 corresponds to the direction of the main magnetic flux of permanent magnets 415 and 416. Angle θ1 is greater than angle θ2.

[0030] In this embodiment, a permanent magnet 41 is arranged on the magnetic pole centerline CL1, and permanent magnets 41 are arranged on both sides of it such that the angle θ1 > θ2. This concentrates the magnetic flux from the permanent magnets 41 towards the rotation center side (axis CL0 side) of the rotor 1, increasing the amount of magnetic flux on the d axis and improving the salient polarity of the magnetic pole section 30. In other words, the salient pole ratio can be increased. As a result, the torque of the rotor 1 can be increased compared to the case where θ1 ≤ θ2. Also, by setting θ1 > θ2, the radial length between the inner magnet housing holes 311~313 and the outer magnet housing holes 314~316 increases from the circumferential outer side toward the magnetic pole centerline CL1. This prevents magnetic saturation from occurring due to the concentration of magnetic flux from the stator 2.

[0031] Furthermore, Figure 2 shows that θ3 represents the angle between the reference line L23, which extends along the inner rib 35 and passes through the center of the inner rib 35 in the width direction, and the magnetic pole centerline CL1. Also, θ4 represents the angle between the reference line L24, which extends along the outer rib 36 and passes through the center of the outer rib 36 in the width direction, and the magnetic pole centerline CL1. Angle θ3 is greater than angle θ4. In other words, the angle in the direction in which the ribs 35 and 36 extend (rib angle) is larger for the inner rib 35 than for the outer rib 36.

[0032] The stress generated in the rotor core 10 tends to be maximum near the inner rib 35. Figure 4 is a contour plot showing an example of the stress analysis results near the inner rib 35. In the figure, to the left of the magnetic pole centerline CL1, an example of the analysis results for the rotor core 10 of this embodiment is shown, where the rib angle θ3 along the reference line L23 is greater than the rib angle θ4 along the reference line L24 (Figure 2). Also, to the right of the magnetic pole centerline CL1, as a reference example, an example of the analysis results for the rotor core is shown when θ3 = θ4, that is, when the inner rib 35B extends along the reference line L23B parallel to the magnetic pole centerline CL1. Note that in the reference example, the flux barrier is not lengthened in the radial direction. In Figure 4, for convenience, region A where the maximum stress above a predetermined value occurs and region B where the stress one step lower than the maximum stress occurs are shown by hatching.

[0033] As shown in Figure 4, in this embodiment, stress is generated more uniformly in the inner rib 35 than in the reference example. This reduces stress concentration near the inner rib 35, enabling higher rotational speeds for the rotor 1.

[0034] Figure 5 schematically shows the main forces acting on the rotor core 10. As shown in Figure 5, the rotor core 10 experiences a reaction force in the circumferential direction due to the centrifugal force acting radially, resulting in a circumferential tensile force F0 acting on the inner circumference of the rotor core 10. Therefore, mainly centrifugal force acts near the outer rib 36, while near the inner rib 35, both centrifugal force and circumferential tensile force F0 act. Consequently, the outer rib 36 experiences a force along its extending direction as shown by arrow F1, while the inner rib 35 experiences a force along its extending direction as shown by arrow F2. This allows the force to act evenly on the inner rib 35, and as a result, stress concentration on the inner rib 35 can be alleviated, as shown in Figure 4.

[0035] Figure 6 is an enlarged view of the inner rib 35 on the side of the second permanent magnet 412. In Figure 6, the flux barrier 33 adjacent to the end face 41a of the first permanent magnet 411 is indicated by reference numeral 331, and the flux barrier 33 adjacent to the end face 41b of the second permanent magnet 412 is indicated by reference numeral 332. As shown in Figure 6, the flux barriers 331 and 332 protrude outward in the thickness direction of the permanent magnets 411 and 412 beyond the magnet housing holes 311 and 312. The length L332 of the flux barrier 332 along the reference line L23 (Figure 2) is longer than the length L331 of the flux barrier 331, and the flux barriers 331 and 332 are formed asymmetrically with respect to the reference line L23.

[0036] Figure 7 is a contour plot showing an example of stress analysis results near the inner rib 35. Similar to Figure 4, Figure 7 shows an example of the analysis results for the rotor core 10 of this embodiment to the left of the magnetic pole centerline CL1, and an example of the analysis results for a rotor core as a reference example to the right of the magnetic pole centerline CL1. In the reference example in Figure 7, the inner rib 35C is provided such that θ3 > θ4, similar to this embodiment. However, unlike this embodiment, the flux barrier in the reference example is not elongated in the radial direction (thickness direction of the permanent magnet 41).

[0037] As shown in Figure 7, in this embodiment, stress is generated more uniformly in the inner rib 35 than in the reference example. This reduces stress concentration near the inner rib 35, enabling higher rotational speeds for the rotor 1.

[0038] Thus, in this embodiment, the flux barriers 331 and 332 are formed to be radially longer than the magnet housing hole 31, so that the force can be absorbed by the air gap (flux barrier), thereby mitigating stress concentration. Furthermore, the flux barrier 332 is made longer than the flux barrier 331, and the flux barriers 331 and 332 are configured asymmetrically with respect to the reference line L23. More specifically, the flux barrier 332 on the side where the force in the direction of arrow F2 in Figure 5 acts is made longer than the other flux barrier 331. This further mitigates stress concentration.

[0039] In the above, the magnetic pole portion 30 of the rotor 1 is provided with inner magnet housing holes 311-313 and outer magnet housing holes 314-316. That is, two layers of magnet housing holes 31 are provided in the radial direction, but three or more layers of magnet housing holes 31 may be provided in the radial direction. Figure 8 shows an example of a magnetic pole portion 30 with three layers of magnet housing holes 31. Note that Figure 8 shows an example of magnetic flux lines 10b from the stator 2, and the illustration of the flux barrier 33 is omitted.

[0040] As shown in Figure 8, the rotor core 10 is provided with a seventh magnet housing hole 317, an eighth magnet housing hole 318, and a ninth magnet housing hole 319, respectively, radially inward from the first magnet housing hole 311, the second magnet housing hole 312, and the third magnet housing hole 313, symmetrically with respect to the magnetic pole centerline CL1. More specifically, the seventh magnet housing hole 317 (third central housing hole) extends circumferentially on the magnetic pole centerline CL1 so as to be perpendicular to the magnetic pole centerline CL1. The eighth magnet housing hole 318 and the ninth magnet housing holes 319 (a pair of third inclined housing holes) extend inclined with respect to the magnetic pole centerline CL1 so as they move away from the magnetic pole centerline CL1, they move radially outward.

[0041] The seventh permanent magnet 417, the eighth permanent magnet 418, and the ninth permanent magnet 419 are housed in the seventh, eighth, and ninth permanent magnet 317, respectively. These permanent magnets 417-419, like the inner permanent magnets 411-413 and the outer permanent magnets 414-416, are substantially rectangular in shape when viewed from the front along the axis CL0, corresponding to the magnet housing holes 31, and are identical or nearly identical in shape to each other. The width of the permanent magnets 417-419 is longer than the width of the inner permanent magnets 411-413. That is, the permanent magnets 41 become longer as they extend radially inward. The width direction of each permanent magnet 411-419 is the same as or nearly the same as the direction in which the magnetic flux lines 10b extend.

[0042] Figure 8 shows the angle θ5 between the extension line L25 of the centerlines CL2 of the eighth permanent magnet 418 and the ninth permanent magnet 419 (for convenience, only the extension line L25 of the ninth permanent magnet 419 is shown) and the magnetic pole centerline CL1. This angle θ5 is larger than the angle θ1 (Figure 2) between the extension line L21 and the magnetic pole centerline. That is, the angles θ1, θ2, and θ5 between the extension lines L21, L22, L25 and the magnetic pole centerline CL1 gradually increase as you move radially inward (θ2 < θ1 < θ5).

[0043] This concentrates the magnetic flux from the permanent magnet 41 towards the rotation center side (axis CL0 side) of the rotor 1, increasing the amount of magnetic flux on the d-axis and improving the salient polarity of the magnetic pole portion 30. Furthermore, increasing the number of layers of the permanent magnet 41 can further increase torque.

[0044] In the above, three magnet housing holes 31 were provided in each layer of the magnetic pole section 30 of the rotor 1, but the number of magnet housing holes 31 in each layer may be five or more, as long as it is an odd number. Figure 9 shows an example of a magnetic pole section 30 in which five magnet housing holes 31 are provided on both the inner and outer circumference sides of the magnetic pole section 30. Note that, as with Figure 8, an example of magnetic flux lines 10b from the stator 2 is shown in Figure 9, and the illustration of the flux barrier 33 is omitted.

[0045] As shown in Figure 9, the rotor core 10 is provided with an eleventh magnet housing hole 3111 and a twelfth magnet housing hole 3112 on the circumferentially outer side of the second magnet housing hole 312 and the third magnet housing hole 313, symmetrically with respect to the magnetic pole centerline CL1. Furthermore, a thirteenth magnet housing hole 3113 and a fourteenth magnet housing hole 3114 are provided on the circumferentially outer side of the fifth magnet housing hole 315 and the sixth magnet housing hole 316, symmetrically with respect to the magnetic pole centerline CL1. The eleventh magnet housing hole 3111 and the twelfth magnet housing hole 3112 are inclined with respect to the magnetic pole centerline CL1 so that they move radially outward as they move away from the magnetic pole centerline CL1. The thirteenth magnet housing hole 3113 and the fourteenth magnet housing hole 3114 are inclined with respect to the magnetic pole centerline CL1 so that they move radially outward as they move away from the magnetic pole centerline CL1.

[0046] The 11th permanent magnet 4111, the 12th permanent magnet 4112, the 13th permanent magnet 4113, and the 14th permanent magnet 4114 are housed in the 11th permanent magnet 4111, the 12th permanent magnet 4112, the 13th permanent magnet 4113, and the 14th permanent magnet 4114, respectively. The 11th permanent magnet 4111 and the 12th permanent magnet 4112 have the same or substantially the same shape as the inner permanent magnets 411-413 on their circumferential inner side. The 13th permanent magnet 4113 and the 14th permanent magnet 4114 have the same or substantially the same shape as the outer permanent magnets 414-416 on their circumferential inner side. The width direction of each permanent magnet 4111-4114 is the same or substantially the same as the direction in which the magnetic flux lines 10b extend.

[0047] Figure 9 shows that the angle between the extension line L27 of the centerlines CL2 of the 11th permanent magnet 4111 and the 12th permanent magnet 4112 (for convenience, only the extension line L27 of the 11th permanent magnet 4111 is shown) and the magnetic pole centerline CL1 is θ7. Also, the angle between the extension line L28 of the centerlines CL2 of the 13th permanent magnet 4113 and the 14th permanent magnet 4114 (for convenience, only the extension line L28 of the 13th permanent magnet 4113 is shown) and the magnetic pole centerline CL1 is θ8.

[0048] Angle θ7 is greater than angle θ8 (θ7 > θ8). Also, angle θ7 is greater than angle θ1 defined by extension line L21 passing through permanent magnets 412 and 413 on the inside in the circumferential direction. Angle θ8 is greater than angle θ2 defined by extension line L22 passing through permanent magnets 415 and 416 on the inside in the circumferential direction. In other words, the angles θ1, θ2, θ7, and θ8 between extension lines L21, L22, L27, and L28 and the magnetic pole centerline CL1 gradually increase as you move away from the magnetic pole centerline CL1 in the circumferential direction (θ1 < θ7, θ2 < θ8).

[0049] This allows for the concentration of magnetic flux from more permanent magnets 41 towards the rotation center side (axis CL0 side) of the rotor 1 without increasing the number of layers of permanent magnets 41, thereby increasing the amount of magnetic flux on the d-axis and improving the salient polarity of the magnetic pole portion 30.

[0050] In this embodiment, the magnetic pole section 30 is arranged in two or more radial layers, with an odd number of permanent magnets 41 (three or more) in each layer. This suppresses demagnetization of the permanent magnets 41 by the demagnetizing field from the stator 2. Figure 10 is a reference example of Figure 2, showing an example of the configuration of the magnetic pole section 30 when the number of permanent magnets 41 on the inner and outer layers are different, and the outer permanent magnets are not arranged on the magnetic pole centerline CL1. As shown in Figure 10, when the number of permanent magnets 41 in each layer is not equal, the ribs 37 and permanent magnets 41 are arranged on a straight line (for example, the magnetic pole centerline CL1), which reduces the permeance coefficient. This may reduce the demagnetization resistance of the permanent magnets 41. Considering this point, it is preferable to make the number of permanent magnets 41 in each layer equal, as in this embodiment.

[0051] This embodiment can provide the following effects and advantages. (1) The rotating electric machine 100 comprises a rotor 1 that rotates about an axis CL0, and a stator 2 that is arranged around the outer circumferential surface 1a of the rotor 1 and generates a rotating magnetic field relative to the rotor 1 (Figure 1). The rotor 1 has a rotor core 10 provided with magnet housing holes 31 extending in the axial direction, permanent magnets 41 housed in the magnet housing holes 31, and is composed of a plurality of circumferential magnetic pole portions 30 (Figure 2). The magnet housing holes 31 include a plurality of magnet housing holes 311 to 316 provided symmetrically with respect to a magnetic pole center line CL1 that extends radially from the axis CL0 in each of the plurality of circumferential magnetic pole portions 30 (Figure 2). The multiple magnet housing holes 311 to 316 include a first magnet housing hole 311 and a fourth magnet housing hole 314, which extend radially inward and radially outward, respectively, perpendicular to the magnetic pole centerline CL1; a second magnet housing hole 312 and a third magnet housing hole 313, which are provided on both sides of the first magnet housing hole 311 in the circumferential direction and extend inclined with respect to the magnetic pole centerline CL1 so as they move away from the magnetic pole centerline CL1; and a fifth magnet housing hole 315 and a sixth magnet housing hole 316, which are provided on both sides of the fourth magnet housing hole 314 in the circumferential direction and extend inclined with respect to the magnetic pole centerline CL1 so as they move away from the magnetic pole centerline CL1 (Figure 2). The permanent magnet 41 includes multiple permanent magnets 411 to 416 housed in the multiple magnet housing holes 311 to 316, each having a longitudinal width and a transverse thickness (Figure 2). The multiple permanent magnets 411 to 416 include a first permanent magnet 411 housed in a first magnet housing hole 311, second permanent magnets 412 and third permanent magnets 413 housed in a second magnet housing hole 312 and a third magnet housing hole 313, a fourth permanent magnet 414 housed in a fourth magnet housing hole 314, and fifth permanent magnets 415 and sixth permanent magnets 416 housed in a fifth magnet housing hole 315 and a sixth magnet housing hole 316 (Figure 2). The rotor core 10 has an inner rib 35 provided between the first magnet housing hole 311 and the second magnet housing hole 312 and the third magnet housing hole 313, and an outer rib 36 provided between the fourth magnet housing hole 314 and the fifth magnet housing hole 315 and the sixth magnet housing hole 316 (Figure 2).The angle θ1 between the extension line L21 extending in the thickness direction from the widthwise center of the second permanent magnet 412 and the third permanent magnet 413 and the magnetic pole center line CL1 is greater than the angle θ2 between the extension line L22 extending in the thickness direction from the widthwise center of the fifth permanent magnet 415 and the sixth permanent magnet 416 and the magnetic pole center line CL1 (Figure 2).

[0052] In this configuration, multiple inner ribs 35 and multiple outer ribs 36 are provided on both sides of the magnetic pole centerline CL1 in the circumferential direction, inclined with respect to the magnetic pole centerline CL1. Therefore, when increasing the rotational speed of the rotor 1, the thickness of the ribs 35 and 36 can be made thinner compared to the case where center ribs 35A and 36A are provided (Figure 3), thereby suppressing leakage flux. In addition, since the permanent magnets 412, 413, 415, and 416 on both sides of the magnetic pole centerline CL1 in the circumferential direction are arranged inclined such that θ1 > θ2, the salient polarity of the rotor 1 is improved. As a result, the maximum torque of the rotor 1 can be increased while ensuring sufficient strength of the rotor 1.

[0053] (2) The inner rib 35 extends between the first magnet housing hole 311, the second magnet housing hole 312, and the third magnet housing hole 313, along the reference line L23 toward the magnetic pole centerline CL1 (Figure 2). The outer rib 36 extends between the fourth magnet housing hole 314, the fifth magnet housing hole 315, and the sixth magnet housing hole 316, along the reference line L24 toward the magnetic pole centerline CL1 (Figure 2). The angle θ3 between the reference line L23 and the magnetic pole centerline CL1 is greater than the angle θ4 between the reference line L24 and the magnetic pole centerline CL1 (Figure 2). This reduces stress concentration in the ribs 35 and 36, enabling higher rotational speeds for the rotor 1.

[0054] (3) The rotor core 10 is further provided with a flux barrier 331 adjacent to the widthwise end of the first magnet housing hole 311, and a flux barrier 332 adjacent to the widthwise ends of the second magnet housing hole 312 and the third magnet housing hole 313, with the inner rib 35 in between (Figure 6). The lengths of the flux barriers 331 and 332 in the direction in which the inner rib 35 extends are greater than or equal to the thickness of the permanent magnet 41, and the length of the flux barrier 332 in the direction in which the inner rib 35 extends is longer than the length of the flux barrier 331 (Figure 6). This makes it possible to alleviate stress concentration in the inner rib 35 and to achieve high rotational speed of the rotor 1.

[0055] (4) The plurality of magnet housing holes 31 further include a seventh magnet housing hole 317 that extends radially inward from the first magnet housing hole 311 so as to be perpendicular to the magnetic pole centerline CL1, and an eighth magnet housing hole 318 and a ninth magnet housing hole 319 provided on both sides of the seventh magnet housing hole 317 in the circumferential direction and extending inclined with respect to the magnetic pole centerline CL1 so as they move away from the magnetic pole centerline CL1 toward the radial pole centerline CL1 (Figure 8). The plurality of permanent magnets 41 further include a seventh permanent magnet 417 housed in the seventh magnet housing hole 317, and an eighth permanent magnet 418 and a ninth permanent magnet 419 housed in the eighth magnet housing hole 318 and the ninth magnet housing hole 319 (Figure 8). The angle θ5 between the extension line L25, which extends in the thickness direction from the widthwise center of the eighth permanent magnet 418 and the ninth permanent magnet 419, and the magnetic pole center line CL1 is greater than the angle θ1 between the extension line L21 and the magnetic pole center line CL1 (Figure 8). This allows for a greater increase in maximum torque while ensuring sufficient strength of the rotor 1.

[0056] This embodiment can be modified into various forms. Several modifications will be described below. In the above embodiment, the rotor core 10 is provided with a plurality of magnet housing holes 31 arranged symmetrically with respect to the magnetic pole centerline CL1. Specifically, a first magnet housing hole 311 is provided as an inner central housing hole, a second magnet housing hole 312 and a third magnet housing hole 313 are provided as a pair of inner inclined housing holes, a fourth magnet housing hole 314 is provided as an outer central housing hole, a fifth magnet housing hole 315 and a sixth magnet housing hole 316 are provided as a pair of outer inclined housing holes, a seventh magnet housing hole 317 is provided as a third central housing hole, and an eighth magnet housing hole 318 and a ninth magnet housing hole 319 are provided as a pair of third inclined housing holes. However, the number and arrangement of magnet housing holes are not limited to those described above, as long as a plurality of radial central housing holes are provided perpendicular to the magnetic pole centerline CL1, and a plurality of inclined housing holes are provided on both sides in the circumferential direction of each central housing hole, so as they move radially outward as they move away from the magnetic pole centerline CL1.

[0057] In the above embodiment, a plurality of substantially rectangular permanent magnets 41 are arranged in a plurality of magnet housing holes 31, and the plurality of permanent magnets 41 include a first permanent magnet 411 as an inner central permanent magnet, a second permanent magnet 412 and a third permanent magnet 413 as a pair of inner inclined permanent magnets, a fourth permanent magnet 414 as an outer central permanent magnet, a fifth permanent magnet 415 and a sixth permanent magnet 416 as a pair of outer inclined permanent magnets, a seventh permanent magnet 417 as a third central permanent magnet, and an eighth permanent magnet 418 and a ninth permanent magnet 419 as a pair of third inclined permanent magnets. However, the shape and number of permanent magnets 41 are not limited to those described above. The permanent magnets 41 may also be configured in an arc shape.

[0058] Regardless of whether the permanent magnet 41 is configured in a roughly rectangular or arc shape, the angle θ1 between the extension line L21 (first reference line) extending in the thickness direction from the center in the width direction of the inner inclined permanent magnet and the magnetic pole center line CL1 should be greater than the angle between the extension line L22 (second reference line) extending in the thickness direction from the center in the width direction of the outer inclined permanent magnet and the magnetic pole center line CL1. Furthermore, if a third central permanent magnet and a third inclined permanent magnet are provided, the angle θ5 between the extension line L25 (fifth reference line) extending in the thickness direction from the center in the width direction of the third inclined permanent magnet and the magnetic pole center line CL1 should be greater than the angle θ1 between the extension line L21 and the magnetic pole center line CL1.

[0059] In the above embodiment, an inner rib 35 is extended from the rotor core 10 between the first magnet housing hole 311, the second magnet housing hole 312, and the third magnet housing hole 313 along a reference line L23 (third reference line) toward the magnetic pole centerline CL1, and an outer rib 36 is extended from the fourth magnet housing hole 314, the fifth magnet housing hole 315, and the sixth magnet housing hole 316 along a reference line L24 (fourth reference line) toward the magnetic pole centerline CL1. However, the configuration of the inner and outer ribs is not limited to the above, as long as the angle θ3 between the reference line L23 and the magnetic pole centerline CL1 is greater than the angle θ4 between the reference line L24 and the magnetic pole centerline CL1. In the above embodiment (Figure 6), of the flux barriers 331 and 332 on both sides of the inner rib 35 in the circumferential direction, flux barrier 332 (second flux barrier) is provided to be longer than flux barrier 331 (first flux barrier). However, the configuration of the flux barrier is not limited to that described above.

[0060] The above description is merely an example, and the present invention is not limited by the embodiments and modifications described above, as long as the features of the present invention are not impaired. It is also possible to arbitrarily combine one or more of the above embodiments and modifications, and to combine modifications with each other. [Explanation of symbols]

[0061] 1 Rotor, 1a Outer surface, 2 Stator, 10 Rotor core, 30 Magnetic pole section, 31 Magnet housing hole, 33 Flux barrier, 35 Inner rib, 36 Outer rib, 41 Permanent magnet, 100 Rotating electric machine, 311 First magnet housing hole, 312 Second magnet housing hole, 313 Third magnet housing hole, 314 Fourth magnet housing hole, 315 Fifth magnet housing hole, 316 Sixth magnet housing hole, 317 Seventh magnet housing hole, 318 Eighth magnet housing hole, 319 Ninth magnet housing hole, 331,332 Flux barrier, 411 First permanent magnet, 412 Second permanent magnet, 413 Third permanent magnet, 414 Fourth permanent magnet, 415 Fifth permanent magnet, 416 Sixth permanent magnet, 417 Seventh permanent magnet, 418 Eighth permanent magnet, 419 Ninth permanent magnet, CL0 Axis, CL1 Magnetic pole center line, L21, L22 extension line, L23, L24, L25 reference line, θ1, θ2, θ3, θ4, θ5 angle

Claims

1. A rotating electric machine comprising a rotor that rotates about an axis, and a stator arranged around the outer surface of the rotor and generating a rotating magnetic field for the rotor, The rotor comprises a rotor core provided with magnet housing holes extending in the axial direction, permanent magnets housed in the magnet housing holes, and is composed of a plurality of circumferential magnetic pole portions. The magnet housing holes include a plurality of magnet housing holes provided symmetrically with respect to a magnetic pole center line extending radially from the axis in each of the plurality of circumferential magnetic pole portions, The plurality of magnet housing holes are, An inner central housing hole and an outer central housing hole extending radially inward and radially outward, respectively, perpendicular to the magnetic pole centerline, A pair of inner inclined housing holes are provided on both sides of the inner central housing hole in the circumferential direction, and are inclined with respect to the magnetic pole centerline so as they move away from the magnetic pole centerline, It includes a pair of outer inclined accommodating holes provided on both sides of the outer central accommodating hole in the circumferential direction, extending inclined with respect to the magnetic pole centerline so as they move away from the magnetic pole centerline, The permanent magnet includes a plurality of permanent magnets housed in the plurality of magnet housing holes, each having a width in the longitudinal direction and a thickness in the short direction. The plurality of permanent magnets include an inner central permanent magnet housed in the inner central housing hole, a pair of inner inclined permanent magnets housed in a pair of inner inclined housing holes, an outer central permanent magnet housed in the outer central housing hole and positioned radially to the outermost edge on the magnetic pole centerline, and a pair of outer inclined permanent magnets housed in a pair of outer inclined housing holes. The rotor core has an inner rib provided between the inner central housing hole and the inner inclined housing hole, and an outer rib provided between the outer central housing hole and the outer inclined housing hole, The width of the inner rib, which is the distance between the inner central housing hole and the inner inclined housing hole, is wider than the width of the outer rib, which is the distance between the outer central housing hole and the outer inclined housing hole. The angle between the first reference line extending in the thickness direction from the center in the width direction of the inner inclined permanent magnet and the magnetic pole center line is greater than the angle between the second reference line extending in the thickness direction from the center in the width direction of the outer inclined permanent magnet and the magnetic pole center line. The inner rib extends between the inner central housing hole and the inner inclined housing hole along a third reference line toward the magnetic pole centerline. The outer rib extends between the outer central housing hole and the outer inclined housing hole along a fourth reference line toward the magnetic pole centerline, The angle between the third reference line and the magnetic pole center line is greater than the angle between the fourth reference line and the magnetic pole center line. The rotating electric machine is characterized in that the fourth reference line does not intersect the magnet housing hole on the radially outer side of the outer rib, but intersects the magnetic pole center line on the radially outer side of the outer circumferential surface of the rotor core.

2. In the rotating electric machine according to Claim 1, The rotor core is further provided with a first flux barrier adjacent to the widthwise end of the inner central housing hole, and a second flux barrier adjacent to the widthwise end of the inner inclined housing hole, with the inner rib in between. A rotating electric machine characterized in that the length of the first flux barrier and the length of the second flux barrier in the direction in which the inner rib extends are greater than or equal to the thickness of the permanent magnet, and the length of the second flux barrier in the direction in which the inner rib extends is longer than the length of the first flux barrier.

3. In the rotating electric machine according to claim 1 or 2, The plurality of magnet housing holes are, A third central housing hole is provided, which extends radially inward from the inner central housing hole so as to be perpendicular to the magnetic pole center line, The present invention further includes a pair of third inclined housing holes provided on both sides of the third central housing hole in the circumferential direction, and extending inclined with respect to the magnetic pole centerline so as they move away from the magnetic pole centerline, The plurality of permanent magnets further include a third central permanent magnet housed in the third central housing hole and a pair of third inclined permanent magnets housed in a pair of the third inclined housing holes, A rotating electric machine characterized in that the angle between the fifth reference line, which extends in the thickness direction from the center in the width direction of the third inclined permanent magnet, and the magnetic pole center line is greater than the angle between the first reference line and the magnetic pole center line.

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