Rotary 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 electric machine having a rotor with embedded permanent magnets. [Background technology]

[0002] Conventionally, there has been known a rotating electric machine configured with a plurality of magnets arranged on the inner and outer circumferential sides of a plurality of magnetic pole portions of a rotor in the circumferential direction (see, for example, Patent Document 1). In the rotating electric machine described in Patent Document 1, a plurality of magnet mounting portions are provided in a substantially V-shape symmetrically with respect to the magnetic pole center on both sides of the magnetic pole center of the plurality of magnetic pole portions in the circumferential direction of the rotor, and a magnet is arranged in each of the plurality of magnet mounting portions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-137139 Summary of the Invention [Problem to be solved by the invention]

[0004] When magnet mounting portions are provided on both sides of the rotor's magnetic pole center, as in the rotating electric machine described in Patent Document 1, the length between the pair of magnet mounting portions on both sides of the rotor's magnetic pole center needs to be increased to ensure sufficient rotor strength. However, increasing the length between the pair of magnet mounting portions increases leakage flux, resulting in a decrease in the rotor's maximum torque. [Means for solving the problem]

[0005] A rotating electric machine according to one aspect of the present invention includes a rotor that rotates about a rotation axis, and a stator disposed around the outer circumferential surface of the rotor and generating a rotating magnetic field relative to the rotor. The rotor has a rotor core provided with magnet accommodating holes extending in the axial direction, and permanent magnets accommodated in the magnet accommodating holes, and is configured with a plurality of circumferential magnetic pole portions, the magnet accommodating holes including a plurality of magnet accommodating holes provided in each of the circumferential magnetic pole portions symmetrically with respect to a magnetic pole center line extending radially from the rotation axis, the plurality of magnet accommodating holes including an inner central accommodating hole and an outer central accommodating hole extending radially inward and radially outward so as to be perpendicular to the magnetic pole center line, a pair of inner inclined accommodating holes provided on both circumferential sides of the inner central accommodating hole and extending at an angle relative to the magnetic pole center line so as to extend radially outward as they move away from the magnetic pole center line, and a pair of outer central accommodating holes provided on both circumferential sides of the outer central accommodating hole and extending at an angle relative to the magnetic pole center line so as to extend radially outward as they move away from the magnetic pole center line. the permanent magnets include a plurality of permanent magnets accommodated in the plurality of magnet accommodating holes and having a longitudinal width and a lateral thickness, the plurality of permanent magnets including an inner central permanent magnet accommodated in the inner central accommodating hole, a pair of inner inclined permanent magnets accommodated in the pair of inner inclined accommodating holes, an outer central permanent magnet accommodated in the outer central accommodating hole, and a pair of outer inclined permanent magnets accommodated in the pair of outer inclined accommodating holes, the rotor core has an inner rib provided between the inner central accommodating hole and the inner inclined accommodating hole, and an outer rib provided between the outer central accommodating hole and the outer inclined accommodating hole, and an angle formed between a first axis extending in the thickness direction from the center of the width direction of the inner inclined permanent magnet and a magnetic pole center line is larger than an angle formed between a second axis extending in the thickness direction from the center of the width direction of the outer inclined permanent magnet and the magnetic pole center line. [Effects of the Invention]

[0006] According to the present invention, the maximum torque of the rotor can be increased while ensuring sufficient strength of the rotor. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view perpendicular to an axis, showing a configuration of a main part of a rotating electric machine according to an embodiment of the present invention; [Figure 2] FIG. 2 is an enlarged view of a main part of FIG. 1 showing the configuration of the magnetic pole portion of the rotor. [Figure 3] FIG. 3 is a diagram showing a reference example of FIG. 2. [Figure 4] FIG. 10 is a contour diagram showing an example of the stress analysis results of the present embodiment and a reference example in the vicinity of the inner rib of the magnetic pole portion. [Figure 5] FIG. 3 is a diagram schematically showing the main directions of forces acting on the magnetic pole portions. [Figure 6] FIG. 3 is an enlarged view of the area near the inner rib in FIG. 2. [Figure 7] 10A and 10B are contour diagrams showing examples of stress analysis results in the vicinity of the inner rib of the magnetic pole portion in this embodiment and other reference examples. [Figure 8] FIG. 3 is a diagram showing a modification of FIG. 2. [Figure 9] FIG. 3 is a diagram showing another modification of FIG. 2. [Figure 10] FIG. 3 is a diagram showing another reference example of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to Figures 1 to 10. A rotating electric machine according to an embodiment of the present invention is mounted on a hybrid vehicle or an electric vehicle and can be used as a motor for driving the vehicle, or can also be used as a generator. Note that the rotating electric machine can also be mounted on equipment other than a vehicle and used for various purposes.

[0009] FIG. 1 is a cross-sectional view perpendicular to an axis CL0, showing the configuration of a main part 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 as the center is defined as the radial direction, and the direction along a circle centered on the axis CL0 as the circumferential direction. As shown in FIG. 1, the rotating electric machine 100 includes a rotor 1 that rotates around the axis CL0, and a stator 2 that is disposed so as to surround an outer peripheral surface 1a of the rotor 1. A gap of a predetermined length is provided between the outer peripheral surface 1a of the rotor 1 and the inner peripheral surface of the stator 2 over the entire circumference.

[0010] The rotor 1 has a rotor core 10 having a substantially annular shape centered on an axis CL0, and a plurality of magnetic pole portions 30 formed in the rotor core 10 in the circumferential direction. A rotor shaft 101 constituting, for example, the output shaft of a rotating electric machine 100 is fitted into an inner peripheral surface 10a of the rotor core 10, and the rotor 1 rotates integrally with the rotor shaft 101. The outer peripheral surface 1a of the rotor 1 corresponds to the outer peripheral surface of the rotor core 10. The rotor core 10 is formed by stacking a plurality of electromagnetic steel plates, which are made of a magnetic metal, in the axial direction.

[0011] A plurality of magnetic pole portions 30 are provided at equal intervals in the circumferential direction. In the example of FIG. 1, six magnetic pole portions 30 are provided at 60° intervals. Each magnetic pole portion 30 has a plurality of magnet accommodating holes 31 (six in the figure) formed in the rotor core 10 and a plurality of permanent magnets 41 accommodated in the magnet accommodating holes 31. FIG. 1 shows a magnetic pole center line CL1 that passes through the circumferential center of the magnetic pole portion 30 and extends radially from the axis CL0. The magnetic pole center line CL1 corresponds to the d-axis of the magnetic pole portion 30 (the main magnetic flux direction of the permanent magnets 41). The magnetic pole center line CL1 is set for each of the plurality of magnetic pole portions 30. The boundary between the plurality of magnetic pole portions 30 corresponds to the q-axis, which is electrically and magnetically perpendicular to the d-axis.

[0012] The stator 2 includes a substantially annular stator core 20 centered on an axis CL0 and disposed at a predetermined radial distance from the outer peripheral surface 1a of the rotor 1, and a coil 21 attached to the stator core 20. The stator core 20 is formed by laminating multiple electromagnetic steel sheets made of a magnetic metal. Although not shown in part, multiple teeth 22 are provided on the inner peripheral surface of the stator core 20, protruding radially inward along the entire circumference. Slots are formed between adjacent teeth 22 in the circumferential direction. The coil 21 is formed, for example, by a winding wound around the teeth 22.

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

[0014] 2 is an enlarged view of a main portion of FIG. 1, illustrating the configuration of a single magnetic pole portion 30. As shown in FIG. 2, the magnetic pole portion 30 is provided with a plurality of magnet accommodating holes 31 that axially penetrate the rotor core 10. The plurality of magnet accommodating holes 31 include three magnet accommodating holes (referred to as inner magnet accommodating holes) provided on the inner circumferential side and three magnet accommodating holes (referred to as outer magnet accommodating holes) provided on the outer circumferential side. These plurality of magnet accommodating holes 31 have a substantially rectangular shape in a 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 accommodating holes include a first magnet accommodating hole (inner central accommodating hole) 311 disposed on the magnetic pole center line CL1, and a second magnet accommodating hole 312 and a third magnet accommodating hole 313 (a pair of inner inclined accommodating holes) disposed on either side of the first magnet accommodating hole 311 in the circumferential direction. The first magnet accommodating hole 311 extends in the circumferential direction so as to be perpendicular to the magnetic pole center line CL1. The second magnet accommodating hole 312 and the third magnet accommodating hole 313 each extend at an incline with respect to the magnetic pole center line CL1 so as to move radially outward as they move away from the magnetic pole center line CL1. Hereinafter, the first magnet accommodating hole 311, the second magnet accommodating hole 312, and the third magnet accommodating hole 313 may be referred to as the inner magnet accommodating holes 311-313.

[0016] The outer magnet accommodating holes include a fourth magnet accommodating hole (outer central accommodating hole) 314 arranged on the magnetic pole center line CL1, and a fifth magnet accommodating hole 315 and a sixth magnet accommodating hole 316 (a pair of outer inclined accommodating holes) arranged on either side of the fourth magnet accommodating hole 314 in the circumferential direction. The fourth magnet accommodating hole 314 extends circumferentially so as to be perpendicular to the magnetic pole center line CL1. The fifth magnet accommodating hole 315 and the sixth magnet accommodating hole 316 each extend at an incline with respect to the magnetic pole center line CL1 so as to move radially outward as they move away from the magnetic pole center line CL1. Hereinafter, the fourth magnet accommodating hole 314, the fifth magnet accommodating hole 315, and the sixth magnet accommodating hole 316 may be referred to as the outer magnet accommodating holes 314-316.

[0017] The outer magnet accommodating holes 314-316 are located radially outward of the inner magnet accommodating holes 311-313. In a cross section perpendicular to the axis CL0, the longitudinal direction of each magnet accommodating hole 31 is called the width, and the lateral direction is called the height. The heights of the magnet accommodating holes 311-316 are the same or nearly the same as one another. The widths of the inner magnet accommodating holes 311-313 are the same or nearly the same as one another. The widths of the outer magnet accommodating holes 314-316 are the same or nearly the same as one another. The width of the inner magnet accommodating holes 311-313 is longer than the width of the outer magnet accommodating holes 314-316.

[0018] The permanent magnets 41 include a first permanent magnet 411 accommodated in the first magnet accommodating hole 311, a second permanent magnet 412 accommodated in the second magnet accommodating hole 312, a third permanent magnet 413 accommodated in the third magnet accommodating hole 313, a fourth permanent magnet 414 accommodated in the fourth magnet accommodating hole 314, a fifth permanent magnet 415 accommodated in the fifth magnet accommodating hole 315, and a sixth permanent magnet 416 accommodated in the sixth magnet accommodating 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 referred to as inner permanent magnets 411-413, and the fourth permanent magnet 414, the fifth permanent magnet 415, and the sixth permanent magnet 416 may be referred to as outer permanent magnets 414-416. The inner permanent magnets 411-413 have the same or nearly the same shape as one another. The outer permanent magnets 414-416 have the same or nearly the same shape as one another.

[0020] When viewed from the front along the axis CL0, the multiple permanent magnets 41 have a generally rectangular shape corresponding to the magnet accommodating holes 31, and are formed like flat plates elongated in the axial direction. 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 lateral direction is referred to as the thickness. The width of the inner permanent magnets 411-413 is greater than the width of the outer permanent magnets 414-416. The thickness of the inner permanent magnets 411-413 is equal to or approximately equal to the thickness of the outer permanent magnets 414-416. Note that the thickness of the inner permanent magnets 411-413 may be greater than the thickness of the outer permanent magnets 414-416.

[0021] The permanent magnets 41 are configured symmetrically with respect to a center line CL2 that passes through the center in the width direction and extends in the thickness direction. The center line CL2 of the first permanent magnet 411 and the center line CL2 of the fourth permanent magnet 414 coincide with the magnetic pole center line CL1. The multiple permanent magnets 41 are magnetized in the thickness direction. For example, the radially outer end faces of the multiple permanent magnets 41 in the thickness direction are each magnetized to an N pole, and the radially inner end faces in the thickness direction are each magnetized to an S pole. The magnetization directions of magnetic pole portions 30 adjacent to each other in the circumferential direction are opposite.

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

[0023] The flux barrier 33 is an air space and has a higher magnetic resistance than the rotor core 10. Providing the flux barrier 33 can prevent the magnetic flux generated by the permanent magnets 41 from being magnetically short-circuited on the rotor side. The flux barrier 33 can also be filled with a resin having a lower magnetic permeability than the rotor core 10, making the flux barrier 33 a resin layer.

[0024] In rotor core 10, ribs 35 (referred to as inner ribs) are provided between first magnet accommodating holes 311 and second magnet accommodating holes 312 and third magnet accommodating holes 313. More specifically, inner ribs 35 are provided between flux barriers 33 adjacent to first magnet accommodating holes 311 and flux barriers 33 adjacent to second magnet accommodating holes 312, and between flux barriers 33 adjacent to first magnet accommodating holes 311 and flux barriers 33 adjacent to third magnet accommodating holes 313. Ribs are also provided between flux barriers 33 adjacent to second magnet accommodating holes 312 and outer peripheral surface 1a of rotor core 10, and between flux barriers 33 adjacent to third magnet accommodating holes 313 and outer peripheral surface 1a of rotor core 10.

[0025] Furthermore, ribs 36 (referred to as outer ribs) are provided in rotor core 10 between fourth magnet accommodating hole 314 and fifth magnet accommodating hole 315 and sixth magnet accommodating hole 316. More specifically, outer ribs 36 are provided between flux barrier 33 adjacent to fourth magnet accommodating hole 314 and flux barrier 33 adjacent to fifth magnet accommodating hole 315, and between flux barrier 33 adjacent to fourth magnet accommodating hole 314 and flux barrier 33 adjacent to sixth magnet accommodating hole 316. Ribs are also provided between flux barrier 33 adjacent to fifth magnet accommodating hole 315 and outer peripheral surface 1a of rotor core 10, and between flux barrier 33 adjacent to sixth magnet accommodating hole 316 and outer peripheral surface 1a of rotor core 10.

[0026] The inner rib 35 extends in a substantially radial direction with a constant or nearly constant width, which is the distance between a pair of adjacent flux barriers 33. Strictly speaking, it extends obliquely toward the magnetic pole center line CL1. The outer rib 36 also extends in a substantially radial direction 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] FIG. 3 is a diagram showing an example of a magnetic pole portion 30A as a reference example of this embodiment. In this reference example, no magnet accommodating hole is located on the magnetic pole center line CL1. Instead, magnet accommodating holes 31A are provided on both the inner and outer circumferential sides of the rotor core 10A, respectively, on both circumferential sides of the magnetic pole center line CL1. A permanent magnet 41A is accommodated in the magnet accommodating hole 31A. The rotor core 10A is provided with ribs (center ribs) 35A, 36A along the magnetic pole center line CL1. In this configuration, when increasing the rotation speed of the rotor 1 (for example, when the rotation speed of the rotor 1 is increased to 20,000 rpm or higher), the center ribs 35A, 36A must be thicker than those shown in FIG. 3 to ensure sufficient strength of the rotor core 10A against centrifugal force. This results in increased leakage flux, which leads to a deterioration in the performance of the rotating electric machine. To prevent this deterioration in the performance of the rotating electric machine, the amount of magnets must be increased.

[0028] In contrast, in this embodiment, as shown in FIG. 2, magnet accommodating holes 31 are provided on the magnetic pole center line CL1 of rotor core 10, and magnet accommodating holes 31 are provided on both circumferential sides of the central magnet accommodating hole 31 via inner ribs 35 and outer ribs 36. As a result, multiple inner ribs 35 and multiple outer ribs 36 are provided on the inner diameter side and the outer diameter side of rotor core 10, respectively, and the overall cross-sectional area of ​​the inner ribs 35 and the outer ribs 36 is increased compared to when a single center rib 35A, 36A is provided. As a result, when increasing the rotation speed of the rotor 1, the thickness of the ribs 35, 36 can be made thinner compared to when center ribs 35A, 36A are provided. This makes it possible to ensure sufficient strength of rotor core 10 while suppressing performance degradation.

[0029] 2, the angle formed by an extension line L21 of the center line CL2 of each 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 center line CL1 is indicated by θ1. Furthermore, the angle formed by an extension line L22 of the center line CL2 of each 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 center line CL1 is indicated by θ2. The extension line L21 corresponds to the direction of the main magnetic flux of the permanent magnets 412 and 413, and the extension line L22 corresponds to the direction of the main magnetic flux of the permanent magnets 415 and 416. The angle θ1 is greater than the angle θ2.

[0030] As described above, in this embodiment, the permanent magnet 41 is disposed on the magnetic pole center line CL1, and the other permanent magnets 41 are disposed on both sides of the magnetic pole center line CL1 so that the angle θ1>θ2 is satisfied. This allows the magnetic flux from the permanent magnet 41 to be concentrated toward the rotation center of the rotor 1 (toward the axis CL0), increasing the amount of magnetic flux on the d-axis and improving the saliency of the magnetic pole portion 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 when θ1≦θ2. Furthermore, by satisfying θ1>θ2, the radial length between the inner magnet accommodating holes 311-313 and the outer magnet accommodating holes 314-316 increases from the circumferential outside toward the magnetic pole center line CL1. This prevents magnetic flux from the stator 2 from concentrating and causing magnetic saturation.

[0031] 2, the angle formed between a reference line L23 that passes through the width center of the inner rib 35 and extends along the inner rib 35 and the magnetic pole center line CL1 is indicated by θ3. Also, the angle formed between a reference line L24 that passes through the width center of the outer rib 36 and extends along the outer rib 36 and the magnetic pole center line CL1 is indicated by θ4. The angle θ3 is larger than the angle θ4. That is, the angle (rib angle) in the direction in which the ribs 35, 36 extend is larger for the inner rib 35 than for the outer rib 36.

[0032] Stress generated in the rotor core 10 tends to be greatest near the inner rib 35. FIG. 4 is a contour diagram showing an example of a stress analysis result near the inner rib 35. In the figure, an example of an analysis result of the rotor core 10 of this embodiment in which the rib angle θ3 along the reference line L23 is greater than the rib angle θ4 along the reference line L24 (FIG. 2) is shown to the left of the magnetic pole center line CL1. Also, an example of an analysis result of the rotor core in the case where θ3=θ4 as a reference example, that is, in the case where the inner rib 35B extends along the reference line L23B parallel to the magnetic pole center line CL1, is shown to the right of the magnetic pole center line CL1. Note that in the reference example, the flux barrier is not elongated in the radial direction. For convenience, FIG. 4 shows, with hatching, a region A where a maximum stress equal to or greater than a predetermined value occurs and a region B where a stress one level lower than the maximum stress occurs.

[0033] 4, in this embodiment, stress is generated more uniformly in the inner rib 35 than in the reference example. This makes it possible to alleviate stress concentration near the inner rib 35, and achieve high rotation speed of the rotor 1.

[0034] FIG. 5 is a diagram schematically illustrating the main forces acting on the rotor core 10. As shown in FIG. 5, a centrifugal force acting in the radial direction on the rotor core 10 causes a reaction force to act in the circumferential direction, resulting in a tensile force F0 acting in the circumferential direction on the inner periphery of the rotor core 10. As a result, the centrifugal force acts mainly near the outer ribs 36, while a circumferential tensile force F0 acts in addition to the centrifugal force near the inner ribs 35. Therefore, a force indicated by arrow F1 acts on the outer ribs 36 in the direction of their extension, while a force indicated by arrow F2 acts on the inner ribs 35 in the direction of their extension. This allows the force to act evenly on the inner ribs 35, thereby reducing stress concentration on the inner ribs 35 as shown in FIG. 4.

[0035] Fig. 6 is an enlarged view of the inner rib 35 on the side of the second permanent magnet 412. In Fig. 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 Fig. 6, the flux barriers 331, 332 are provided to protrude outward in the thickness direction of the permanent magnets 411, 412 beyond the magnet accommodating holes 311, 312. The length L332 of the flux barrier 332 along the reference line L23 (Fig. 2) is longer than the length L331 of the flux barrier 331, and the flux barriers 331, 332 are formed asymmetrically with respect to the reference line L23.

[0036] FIG. 7 is a contour diagram showing an example of stress analysis results in the vicinity of the inner rib 35. In FIG. 7, as in FIG. 4, an example of analysis results for the rotor core 10 of this embodiment is shown to the left of the magnetic pole center line CL1, and an example of analysis results for a rotor core as a reference example is shown to the right of the magnetic pole center line CL1. In the reference example of FIG. 7, like this embodiment, the inner rib 35C is provided so that θ3 > θ4. However, unlike this embodiment, in the reference example, the flux barrier is not elongated in the radial direction (thickness direction of the permanent magnet 41).

[0037] 7, in this embodiment, stress is generated more uniformly in the inner rib 35 than in the reference example. This makes it possible to alleviate stress concentration near the inner rib 35, and achieve high rotation speed of the rotor 1.

[0038] In this manner, in this embodiment, the flux barriers 331, 332 are formed to be longer in the radial direction than the magnet accommodating hole 31, so that the force can be absorbed by the gap (flux barrier), thereby alleviating stress concentration. Also, the flux barrier 332 is made longer than the flux barrier 331, and the flux barriers 331, 332 are configured asymmetrically with respect to the reference line L23. More specifically, the flux barrier 332 on the side where a force in the direction of arrow F2 in FIG. 5 acts is made longer than the other flux barrier 331. This makes it possible to further alleviate stress concentration.

[0039] In the above, the inner magnet accommodating holes 311-313 and the outer magnet accommodating holes 314-316 are provided in the magnetic pole portion 30 of the rotor 1. That is, two layers of magnet accommodating holes 31 are provided in the radial direction, but three or more layers of magnet accommodating holes 31 may be provided in the radial direction. FIG. 8 is a diagram showing an example of a magnetic pole portion 30 in which three layers of magnet accommodating holes 31 are provided in the magnetic pole portion 30. Note that FIG. 8 shows an example of magnetic flux lines 10b from the stator 2, and does not show the flux barrier 33.

[0040] 8, rotor core 10 is provided with seventh, eighth, and ninth magnet accommodating holes 317, 318, and 319 radially inward of first, second, and third magnet accommodating holes 311, 312, and 313, respectively, symmetrically about magnetic pole center line CL1. More specifically, seventh magnet accommodating hole 317 (third central accommodating hole) is provided on magnetic pole center line CL1 and extends in the circumferential direction so as to be perpendicular to magnetic pole center line CL1. Eighth magnet accommodating hole 318 and ninth magnet accommodating hole 319 (a pair of third inclined accommodating holes) are provided extending radially outward with an inclination with respect to magnetic pole center line CL1 as they move away from magnetic pole center line CL1.

[0041] The seventh magnet accommodating hole 317, the eighth magnet accommodating hole 318, and the ninth magnet accommodating hole 319 accommodate a seventh permanent magnet 417, an eighth permanent magnet 418, and a ninth permanent magnet 419, respectively. Like the inner permanent magnets 411-413 and the outer permanent magnets 414-416, these permanent magnets 417-419 have a generally rectangular shape corresponding to the magnet accommodating hole 31 in a front view along the axis CL0, and are identical or nearly identical to one another. The width of the permanent magnets 417-419 is greater than the width of the inner permanent magnets 411-413. In other words, the permanent magnets 41 become longer as they extend radially inward. The width direction of each permanent magnet 411-419 is the same or nearly the same as the direction in which the magnetic flux lines 10b extend.

[0042] In Figure 8, the angle θ5 is the angle formed between the magnetic pole center line CL1 and an extension line L25 (for convenience, only the extension line L25 of the ninth permanent magnet 419 is shown) of the center line CL2 of the eighth permanent magnet 418 and the ninth permanent magnet 419. This angle θ5 is larger than the angle θ1 (Figure 2) formed between the extension line L21 and the magnetic pole center line. In other words, the angles θ1, θ2, and θ5 formed between the extension lines L21, L22, and L25 and the magnetic pole center line CL1 gradually increase toward the radially inward direction (θ2<θ1<θ5).

[0043] This allows the magnetic flux from the permanent magnets 41 to be concentrated toward the rotation center of the rotor 1 (toward the axis CL0), increasing the amount of magnetic flux on the d-axis and improving the saliency of the magnetic pole portions 30. Furthermore, by increasing the number of layers of the permanent magnets 41, it is possible to further increase torque.

[0044] In the above, three magnet accommodating holes 31 are provided in each layer of the magnetic pole section 30 of the rotor 1, but the number of magnet accommodating holes 31 in each layer may be five or more as long as it is an odd number. Fig. 9 is a diagram showing an example of a magnetic pole section 30 in which five magnet accommodating holes 31 are provided on each of the inner and outer circumferential sides of the magnetic pole section 30. Note that, like Fig. 8, Fig. 9 shows an example of magnetic flux lines 10b from the stator 2, but does not show the flux barriers 33.

[0045] 9 , rotor core 10 is provided with eleventh and twelfth magnet accommodating holes 3111 and 3112 symmetrically about the magnetic pole center line CL1, circumferentially outward of second and third magnet accommodating holes 312 and 313. Furthermore, thirteenth and fourteenth magnet accommodating holes 3113 and 3114 symmetrically about the magnetic pole center line CL1, circumferentially outward of fifth and sixth magnet accommodating holes 315 and 316. Eleventh and twelfth magnet accommodating holes 3111 and 3112 extend at an angle relative to magnetic pole center line CL1, so as to extend radially outward as they move away from magnetic pole center line CL1. Thirteenth and fourteenth magnet accommodating holes 3113 and 3114 extend at an angle relative to magnetic pole center line CL1, so as to extend radially outward as they move away from magnetic pole center line CL1.

[0046] The eleventh magnet accommodating hole 3111, the twelfth magnet accommodating hole 3112, the thirteenth magnet accommodating hole 3113, and the fourteenth magnet accommodating hole 3114 accommodate an eleventh permanent magnet 4111, a twelfth permanent magnet 4112, a thirteenth permanent magnet 4113, and a fourteenth permanent magnet 4114, respectively. The eleventh permanent magnet 4111 and the twelfth permanent magnet 4112 have the same or nearly the same shape as the inner permanent magnets 411-413 located circumferentially inward. The thirteenth permanent magnet 4113 and the fourteenth permanent magnet 4114 have the same or nearly the same shape as the outer permanent magnets 414-416 located circumferentially inward. The width direction of each permanent magnet 4111-4114 is the same or nearly the same as the direction in which the magnetic flux lines 10b extend.

[0047] 9, the angle formed by an extension line L27 of the center line CL2 of the eleventh permanent magnet 4111 and the twelfth permanent magnet 4112 (for convenience, only the extension line L27 of the eleventh permanent magnet 4111 is shown) and the magnetic pole center line CL1 is indicated by θ7. Also, the angle formed by an extension line L28 of the center line CL2 of the thirteenth permanent magnet 4113 and the fourteenth permanent magnet 4114 (for convenience, only the extension line L28 of the thirteenth permanent magnet 4113 is shown) and the magnetic pole center line CL1 is indicated by θ8.

[0048] Angle θ7 is larger than angle θ8 (θ7>θ8). Furthermore, angle θ7 is larger than angle θ1 defined by extension line L21 passing through the circumferentially inner permanent magnets 412 and 413. Angle θ8 is larger than angle θ2 defined by extension line L22 passing through the circumferentially inner permanent magnets 415 and 416. In other words, the angles θ1, θ2, θ7, and θ8 formed between extension lines L21, L22, L27, and L28 and magnetic pole center line CL1 gradually increase with increasing distance from magnetic pole center line CL1 in the circumferential direction (θ1<θ7, θ2<θ8).

[0049] This allows the magnetic flux from more permanent magnets 41 to be concentrated toward the center of rotation of the rotor 1 (toward the axis CL0) without increasing the number of layers of the permanent magnets 41, thereby increasing the amount of magnetic flux on the d-axis and improving the saliency 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 prevents the permanent magnets 41 from being demagnetized by the demagnetizing field from the stator 2. FIG. 10 is a reference example of FIG. 2, showing an example of the configuration of the magnetic pole section 30 when the numbers of inner and outer permanent magnets 41 are different and the outer permanent magnets are not arranged on the magnetic pole center line CL1. As shown in FIG. 10, when the numbers of permanent magnets 41 in each layer are not equal, the ribs 37 and the permanent magnets 41 are arranged on a straight line (e.g., the magnetic pole center line CL1), resulting in a decrease in the permeance coefficient. This may result in a decrease in the demagnetization resistance of the permanent magnets 41. Considering this point, it is preferable to have the same number of permanent magnets 41 in each layer, as in this embodiment.

[0051] According to this embodiment, the following effects can be achieved. (1) A rotating electric machine 100 includes a rotor 1 that rotates around an axis CL0, and a stator 2 that is disposed around an outer peripheral surface 1a of the rotor 1 and generates a rotating magnetic field for the rotor 1 (FIG. 1). The rotor 1 has a rotor core 10 that has magnet accommodating holes 31 that extend in the axial direction, and permanent magnets 41 that are accommodated in the magnet accommodating holes 31, and is configured with a plurality of magnetic pole portions 30 arranged in the circumferential direction (FIG. 2). The magnet accommodating holes 31 include a plurality of magnet accommodating holes 311 to 316 that are arranged symmetrically with respect to a magnetic pole center line CL1 that extends radially from the axis CL0, in each of the plurality of magnetic pole portions 30 arranged in the circumferential direction (FIG. 2). The multiple magnet accommodating holes 311-316 include a first magnet accommodating hole 311 and a fourth magnet accommodating hole 314, which extend radially inward and radially outward, respectively, perpendicular to the magnetic pole center line CL1, a second magnet accommodating hole 312 and a third magnet accommodating hole 313, which are provided on both circumferential sides of the first magnet accommodating hole 311 and extend at an angle with respect to the magnetic pole center line CL1 so as to move radially outward as they move away from the magnetic pole center line CL1, and a fifth magnet accommodating hole 315 and a sixth magnet accommodating hole 316, which are provided on both circumferential sides of the fourth magnet accommodating hole 314 and extend at an angle with respect to the magnetic pole center line CL1 so as to move radially outward as they move away from the magnetic pole center line CL1 (FIG. 2). The permanent magnets 41 are accommodated in the multiple magnet accommodating holes 311-316 and include multiple permanent magnets 411-416, each having a width in the longitudinal direction and a thickness in the lateral direction (FIG. 2). The multiple permanent magnets 411-416 include a first permanent magnet 411 accommodated in the first magnet accommodating hole 311, a second permanent magnet 412 and a third permanent magnet 413 accommodated in the second magnet accommodating hole 312 and the third magnet accommodating hole 313, a fourth permanent magnet 414 accommodated in the fourth magnet accommodating hole 314, and a fifth permanent magnet 415 and a sixth permanent magnet 416 accommodated in the fifth magnet accommodating hole 315 and the sixth magnet accommodating hole 316 (FIG. 2). The rotor core 10 has inner ribs 35 provided between the first magnet accommodating hole 311 and the second magnet accommodating hole 312 and the third magnet accommodating hole 313, and outer ribs 36 provided between the fourth magnet accommodating hole 314 and the fifth magnet accommodating hole 315 and the sixth magnet accommodating hole 316 (FIG. 2).The angle θ1 formed between an extension line L21 extending in the thickness direction from the center of the width direction of the second permanent magnet 412 and the third permanent magnet 413 and the magnetic pole center line CL1 is larger than the angle θ2 formed between an extension line L22 extending in the thickness direction from the center of the width direction of the fifth permanent magnet 415 and the sixth permanent magnet 416 and the magnetic pole center line CL1 (Figure 2).

[0052] According to this configuration, multiple inner ribs 35 and multiple outer ribs 36 are provided on both circumferential sides of the magnetic pole center line CL1, inclined relative to the magnetic pole center line CL1. Therefore, when increasing the rotational speed of the rotor 1, the thickness of the ribs 35 and 36 can be made thinner than when center ribs 35A and 36A are provided (FIG. 3), thereby suppressing leakage magnetic flux. Furthermore, since the permanent magnets 412, 413, 415, and 416 on both circumferential sides of the magnetic pole center line CL1 are arranged with an inclination such that θ1 > θ2, the saliency of the rotor 1 is improved. This allows the rotor 1 to increase its maximum torque while ensuring sufficient strength.

[0053] (2) The inner rib 35 extends between the first magnet accommodating hole 311 and the second and third magnet accommodating holes 312 and 313 along a reference line L23 that faces the magnetic pole center line CL1 (FIG. 2). The outer rib 36 extends between the fourth magnet accommodating hole 314 and the fifth and sixth magnet accommodating holes 315 and 316 along a reference line L24 that faces the magnetic pole center line CL1 (FIG. 2). The angle θ3 between the reference line L23 and the magnetic pole center line CL1 is greater than the angle θ4 between the reference line L24 and the magnetic pole center line CL1 (FIG. 2). This reduces stress concentration on the ribs 35 and 36, enabling the rotor 1 to rotate at higher speeds.

[0054] (3) The rotor core 10 is further provided with a flux barrier 331 adjacent to the widthwise end of the first magnet accommodating hole 311 and a flux barrier 332 adjacent to the widthwise end of the second magnet accommodating hole 312 and the third magnet accommodating hole 313, with the inner rib 35 sandwiched between them (FIG. 6). The length of the flux barriers 331, 332 in the direction in which the inner rib 35 extends is equal to or greater than 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 (FIG. 6). This makes it possible to alleviate stress concentration on the inner rib 35, thereby enabling the rotor 1 to rotate at higher speeds.

[0055] (4) The multiple magnet accommodating holes 31 further include a seventh magnet accommodating hole 317 extending radially inward from the first magnet accommodating hole 311 so as to be perpendicular to the magnetic pole center line CL1, and an eighth magnet accommodating hole 318 and a ninth magnet accommodating hole 319 provided on both circumferential sides of the seventh magnet accommodating hole 317 and extending at an angle with respect to the magnetic pole center line CL1 so as to move radially outward with increasing distance from the magnetic pole center line CL1 ( FIG. 8 ). The multiple permanent magnets 41 further include a seventh permanent magnet 417 accommodated in the seventh magnet accommodating hole 317, and an eighth permanent magnet 418 and a ninth permanent magnet 419 accommodated in the eighth magnet accommodating hole 318 and the ninth magnet accommodating hole 319 ( FIG. 8 ). The angle θ5 formed by the extension line L25 extending in the thickness direction from the center of the width direction of the eighth permanent magnet 418 and the ninth permanent magnet 419 and the magnetic pole center line CL1 is larger than the angle θ1 formed by the extension line L21 and the magnetic pole center line CL1 (FIG. 8). This allows the rotor 1 to have sufficient strength while further increasing the maximum torque.

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

[0057] In the above embodiment, a plurality of substantially rectangular permanent magnets 41 are arranged in a plurality of magnet accommodating 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 the permanent magnets 41 are not limited to those described above. The permanent magnets 41 may be configured in an arc shape.

[0058] Whether the permanent magnet 41 is configured in a substantially rectangular shape or a circular arc shape, it is sufficient that the angle θ1 formed between the magnetic pole center line CL1 and an extension line L21 (first reference line) extending in the thickness direction from the center of the width direction of the inner inclined permanent magnet is larger than the angle formed between the magnetic pole center line CL1 and an extension line L22 (second reference line) extending in the thickness direction from the center of the width direction of the outer inclined permanent magnet. Furthermore, when a third central permanent magnet and a third inclined permanent magnet are provided, it is sufficient that the angle θ5 formed between the magnetic pole center line CL1 and an extension line L25 (fifth reference line) extending in the thickness direction from the center of the width direction of the third inclined permanent magnet is larger than the angle θ1 formed between the extension line L21 and the magnetic pole center line CL1.

[0059] In the above embodiment, the inner ribs 35 extend along the reference line L23 (third reference line) toward the magnetic pole center line CL1 between the first magnet accommodating holes 311 and the second and third magnet accommodating holes 312 and 313 in the rotor core 10, and the outer ribs 36 extend along the reference line L24 (fourth reference line) toward the magnetic pole center line CL1 between the fourth magnet accommodating holes 314 and the fifth and sixth magnet accommodating holes 315 and 316. However, the configuration of the inner ribs and outer ribs is not limited to that described above as long as the angle θ3 formed between the reference line L23 and the magnetic pole center line CL1 is greater than the angle θ4 formed between the reference line L24 and the magnetic pole center line CL1. In the above embodiment (FIG. 6), of the flux barriers 331, 332 on both circumferential sides of the inner rib 35, the flux barrier 332 (second flux barrier) is provided longer than the flux barrier 331 (first flux barrier), but 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 to the above-described embodiment and modifications as long as the features of the present invention are not impaired. One or more of the above-described embodiment and modifications can be arbitrarily combined, and modifications can also be combined with each other. [Explanation of symbols]

[0061] REFERENCE SIGNS LIST 1 rotor, 1a outer peripheral surface, 2 stator, 10 rotor core, 30 magnetic pole portion, 31 magnet accommodating hole, 33 flux barrier, 35 inner rib, 36 outer rib, 41 permanent magnet, 100 rotating electric machine, 311 first magnet accommodating hole, 312 second magnet accommodating hole, 313 third magnet accommodating hole, 314 fourth magnet accommodating hole, 315 fifth magnet accommodating hole, 316 sixth magnet accommodating hole, 317 seventh magnet accommodating hole, 318 eighth magnet accommodating hole, 319 ninth magnet accommodating 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 including a rotor that rotates around an axis, and a stator that is disposed around an outer circumferential surface of the rotor and generates a rotating magnetic field relative to the rotor, The rotor has a rotor core provided with magnet accommodating holes extending in the axial direction, permanent magnets accommodated in the magnet accommodating holes, and is configured with a plurality of magnetic pole portions in the circumferential direction, the magnet accommodating holes include a plurality of magnet accommodating 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 accommodating holes are an inner central receiving hole and an outer central receiving hole extending radially inward and radially outward, respectively, so as to be perpendicular to the magnetic pole center line; a pair of inner inclined accommodating holes provided on both circumferential sides of the inner central accommodating hole, the inner inclined accommodating holes extending radially outward as they move away from the magnetic pole center line, and the inner inclined accommodating holes extending radially outward as they move away from the magnetic pole center line; a pair of outer inclined accommodating holes provided on both circumferential sides of the outer central accommodating hole, the outer inclined accommodating holes extending at an angle with respect to the magnetic pole center line so as to move radially outward as they move away from the magnetic pole center line, the permanent magnets include a plurality of permanent magnets accommodated in the plurality of magnet accommodating holes, each having a width in a longitudinal direction and a thickness in a lateral direction, the plurality of permanent magnets include an inner central permanent magnet accommodated in the inner central accommodating hole, a pair of inner inclined permanent magnets accommodated in the pair of inner inclined accommodating holes, an outer central permanent magnet accommodated in the outer central accommodating hole, and a pair of outer inclined permanent magnets accommodated in the pair of outer inclined accommodating holes, the rotor core has an inner rib provided between the inner central accommodating hole and the inner inclined accommodating hole, and an outer rib provided between the outer central accommodating hole and the outer inclined accommodating hole, a rotating electric machine characterized in that an angle formed between a first reference line extending in a thickness direction from a center of a width direction of the inner inclined permanent magnet and the magnetic pole center line is larger than an angle formed between a second reference line extending in a thickness direction from a center of a width direction of the outer inclined permanent magnet and the magnetic pole center line.

2. 2. The rotating electric machine according to claim 1, the inner rib extends between the inner central accommodating hole and the inner inclined accommodating hole along a third reference line directed toward the magnetic pole center line, the outer rib extends between the outer central accommodating hole and the outer inclined accommodating hole along a fourth reference line directed toward the magnetic pole center line, The rotating electric machine according to claim 1, wherein the angle formed between the third reference line and the magnetic pole center line is larger than the angle formed between the fourth reference line and the magnetic pole center line.

3. 2. The rotating electric machine according to claim 1, the rotor core is further provided with a first flux barrier adjacent to a width direction end of the inner central accommodating hole and a second flux barrier adjacent to a width direction end of the inner inclined accommodating hole, with the inner rib sandwiched therebetween; a length of the first flux barrier and a length of the second flux barrier in the direction in which the inner rib extends are equal to or greater than a 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.

4. 4. The rotating electric machine according to claim 1, The plurality of magnet accommodating holes are a third central accommodating hole extending radially inward from the inner central accommodating hole so as to be perpendicular to the magnetic pole center line; a pair of third inclined accommodating holes provided on both circumferential sides of the third central accommodating hole, extending at an angle with respect to the magnetic pole center line so as to extend radially outward as the distance from the magnetic pole center line increases, the plurality of permanent magnets further include a third central permanent magnet accommodated in the third central accommodating hole and a pair of third inclined permanent magnets accommodated in the pair of third inclined accommodating holes, A rotating electric machine characterized in that the angle formed between a fifth reference line extending in the thickness direction from the center of the width direction of the third inclined permanent magnet and the magnetic pole center line is larger than the angle formed between the first reference line and the magnetic pole center line.

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