Rotor for rotary electric machine

Abstract

The invention discloses a rotor for a rotary electric machine. The rotor comprises a rotor core; a first-layer permanent magnet disposed in the first-layer magnet hole; and a second-layer permanent magnet disposed in the second-layer magnet hole. The magnet angle of one magnet sheet is an angle formed by a reference line extending in a direction perpendicular to the d-axis from an intersection point between the d-axis and the extending direction of the side surface in the main magnetic flux direction in the one magnet sheet when viewed in the axial direction, and the extending direction of the side surface. When the side closer to the radial inner side than the reference line when viewed in the axial direction is set as the positive side of the magnet angle, the first magnet angle of a first magnet piece on the d axis or closest to the d axis of the permanent magnets forming the first layer is smaller than the second magnet angle of a second magnet piece on the d axis or closest to the d axis of the permanent magnets forming the second layer.

Description

Technical Field

[0001] The present disclosure relates to a rotor for a rotating electrical machine. Background Art

[0002] A known structure is one in which a plurality of permanent magnets are arranged in two layers, one radially inner and one radially outer, on a rotor core.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-107370 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] In the case of this two-layer configuration structure (the same applies to multi-layer configuration structures with three or more layers), in order to cope with the increase in centrifugal force associated with the high rotation of the rotating motor, the magnet holes of the radially outer layer (herein, referred to as the "magnet holes of the first layer") or the magnet holes of the radially inner layer (herein, referred to as the "magnet holes of the second layer") are sometimes formed to be convex radially outward with the d-axis as the center when viewed along the axial direction.

[0008] However, in this structure, analysis shows that depending on the angle of the radially outward convex shape of the magnet hole of the first layer, the angle of the radially outward convex shape of the magnet hole of the second layer, and the relationship between these two angles, a significant increase in back electromotive force or a decrease in reluctance torque may sometimes occur.

[0009] Therefore, in one aspect, the present disclosure aims to achieve an increase in reluctance torque without significantly increasing or reducing back EMF.

[0010] Technical means to solve the problem

[0011] In one aspect, a rotor for a rotating electrical machine is provided, wherein:

[0012] include:

[0013] The rotor core is formed with a first layer of magnet holes, the magnet holes of the first layer being symmetrical with respect to the d-axis when viewed in the axial direction, and a second layer of magnet holes, the magnet holes of the second layer being radially inward of the magnet holes of the first layer and symmetrical with respect to the d-axis when viewed in the axial direction;

[0014] The permanent magnets of the first layer are disposed in the magnet holes of the first layer; and

[0015] The second layer of permanent magnets is disposed in the magnet holes of the second layer;

[0016] The rotor core includes: a first portion located radially outward of the magnet holes of the first layer and forming an outer peripheral surface of the rotor core; a second portion passing between the magnet holes of the first layer and the magnet holes of the second layer and extending circumferentially to the outer peripheral surface of the rotor core; and a third portion passing radially inward of the magnet holes of the second layer and extending circumferentially to the outer peripheral surface of the rotor core.

[0017] When the magnet angle of a magnet piece is defined as the angle formed by a reference line extending in a direction perpendicular to the d-axis from the intersection of the extension direction of the side surface in the main magnetic flux direction of the magnet piece and the d-axis when viewed in the axial direction, and the extension direction of the side surface, and the side radially inward of the reference line when viewed in the axial direction is defined as the positive side of the magnet angle,

[0018] The first magnet angle of the first magnet piece forming the first layer of permanent magnets and located on or closest to the d-axis is smaller than the second magnet angle of the second magnet piece forming the second layer of permanent magnets and located on or closest to the d-axis.

[0019] Effects of the Invention

[0020] In one aspect, according to the present disclosure, it is possible to achieve an increase in reluctance torque without significantly increasing or reducing back EMF. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a cross-sectional view schematically showing the cross-sectional structure of a motor according to an embodiment.

[0022] Figure 2 is a cross-sectional view of the rotor.

[0023] Figure 3 yes Figure 2 A partially enlarged view of a magnetic pole is shown (part 1).

[0024] Figure 4 yes Figure 2 A partial enlarged view of one magnetic pole shown (part 2).

[0025] Figure 5 This is an explanatory diagram (part 1) of the effects of this embodiment based on the analysis results.

[0026] Figure 6 This is an explanatory diagram (part 2) of the effects of this embodiment based on the analysis results.

[0027] Figure 7 This is an explanatory diagram (part 3) of the effects of this embodiment based on the analysis results.

[0028] Figure 8This is an explanatory diagram (part 4) of the effects of this embodiment based on the analysis results.

[0029] Figure 9 This is an explanatory diagram (part 5) of the effects of this embodiment based on the analysis results. DETAILED DESCRIPTION

[0030] The following describes various embodiments in detail with reference to the accompanying drawings. The dimensional ratios in the drawings are merely examples and are not intended to be limiting. For ease of explanation, shapes and other aspects of the drawings may be partially exaggerated. In the drawings, for ease of viewing, reference numerals may be assigned to only some of the components with the same attributes.

[0031] Figure 1 It is a cross-sectional view schematically showing the cross-sectional structure of the motor 1 according to one embodiment. Figure 2 It is a cross-sectional view of the rotor 30 (a cross-sectional view taken along a plane perpendicular to the axial direction).

[0032] exist Figure 1 , the rotating shaft 12 of the motor 1 is shown. In the following description, the axial direction refers to the direction in which the rotating shaft (rotation center) 12 of the motor 1 extends, and the radial direction refers to the radial direction centered on the rotating shaft 12. Therefore, the radially outer side refers to the side away from the rotating shaft 12, and the radially inner side refers to the side toward the rotating shaft 12. Furthermore, the circumferential direction corresponds to the direction of rotation around the rotating shaft 12.

[0033] The motor 1 may be a vehicle driving motor used in, for example, a hybrid vehicle or an electric vehicle, but the motor 1 may also be used for any other purpose.

[0034] The motor 1 is an inner rotor type, and the stator 21 is provided around the radially outer side of the rotor 30. The stator 21 is fixed to the motor housing 10. The stator 21 has a stator core 211 composed of, for example, an annular magnetic laminated steel plate. A plurality of slots (not shown) are formed radially inside the stator core 211, around which the coils 22 are wound.

[0035] The rotor 30 is arranged radially inside the stator 21 .

[0036] The rotor 30 includes a rotor core 32 , a rotor shaft 34 , end plates 35A and 35B, and magnet pieces 61 and 62 .

[0037] The rotor core 32 is fixed to the radially outer surface of the rotor shaft 34 and rotates integrally with the rotor shaft 34. The rotor core 32 has an axial hole 320 (see Figure 2), and the rotor shaft 34 is fitted into the shaft hole 320. The rotor core 32 can be fixed to the rotor shaft 34 by shrink fit, press fit, or similar means. For example, the rotor core 32 can also be coupled to the rotor shaft 34 by keying or splined coupling. The rotor shaft 34 is rotatably supported by the motor housing 10 via bearings 14a and 14b. Furthermore, the rotor shaft 34 defines the rotating shaft 12 of the motor 1.

[0038] The rotor core 32 is formed of, for example, an annular magnetic laminated steel plate. Magnet pieces 61 and 62 are embedded in the rotor core 32 (see FIG. Figure 2 That is, the rotor core 32 has magnet holes 321 and 322 that penetrate in the axial direction (see Figure 2 ), magnet pieces 61, 62 are inserted and fixed in the magnet holes 321, 322. In a modified example, the rotor core 32 may be formed of a powder compact formed by compressing and solidifying magnetic powder.

[0039] The rotor core 32 is designed to have a circular shape with a first radius r1. In a modified example, the circular shape of the rotor core 32 does not need to be a perfect circle, and may be a circular shape having a notch in a portion, for example.

[0040] like Figure 2 As shown, the rotor core 32 has a rotationally symmetrical shape with the rotation axis 12 as the center when viewed in the axial direction. Figure 2 In the illustrated example, the rotor core 32 is configured such that each set of magnet pieces 61 and 62 overlaps each other every time the rotor core 32 rotates 45 degrees around the rotation shaft 12 .

[0041] The plurality of magnet pieces 61 and 62 are in the form of sintered magnets and can be formed of neodymium or the like. Figure 2 As shown, the plurality of magnet pieces 61 and 62 are arranged in pairs when viewed in the axial direction. In this case, a common magnetic pole is formed between a pair of magnet pieces 61 and a pair of magnet pieces 62. In addition, the plurality of magnet pieces 61 and 62 are arranged in a manner such that the S pole and the N pole appear alternately in the circumferential direction. In addition, in the present embodiment, the number of magnetic poles is eight, but the number of magnetic poles is arbitrary. In addition, in the present embodiment, the magnet pieces 61 and 62 are in the same straight-line shape when viewed in the axial direction, or they may be in different shapes. In addition, at least either one of the magnet pieces 61 and 62 may also be in an arc-shaped shape when viewed in the axial direction.

[0042] In addition, Figure 1 , a motor 1 having a specific structure is shown, but the structure of the motor 1 is not limited to this specific structure. Figure 1 In the embodiment, the rotor shaft 34 is hollow, but it can also be solid.

[0043] Next, refer to Figure 3 The following figures will explain the rotor core 32 and the magnet pieces 61 and 62 in more detail. Although the structure of one magnetic pole will be explained below, the structures of the other magnetic poles may be the same.

[0044] Figure 3 yes Figure 2 The structure of a magnetic pole is basically relative to the d-axis (in the direction of the main magnetic flux (the direction of the field magnetic pole) corresponding to the direction of the main magnetic flux (the direction of the field magnetic pole). Figure 3 The d-axis (in English, "d-axis") symmetry is achieved. The direction of the d-axis corresponds to the direction of the magnetic field generated by magnet segments 61 and 62 arranged on rotor 30. Hereinafter, the circumferentially outer side refers to the side away from the d-axis, and the circumferentially inner side refers to the side closer to the d-axis.

[0045] The rotor core 32 is formed with magnet holes 321 (hereinafter referred to as “first-layer magnet holes 321 ”) and magnet holes 322 (hereinafter referred to as “second-layer magnet holes 322 ”).

[0046] The magnet holes 321 of the first layer are formed in pairs in a roughly V-shape (a roughly V-shape that opens radially outward or radially inward). However, in a modified example, the magnet holes 321 of the first layer can also be formed in pairs in a straight line, or can be achieved by a single straight line (a straight line perpendicular to the d-axis). A magnet piece 61 is provided in each of the magnet holes 321 of the first layer. In addition, a gap is provided between the magnet holes 321 of the first layer and the magnet piece 61 at both ends in the longitudinal direction of the magnet piece 61. In addition, the gap can be a cavity or can be filled with resin, etc.

[0047] The second-layer magnet holes 322 are positioned radially inward relative to the first-layer magnet holes 321. Regarding the positional relationship between the first-layer magnet holes 321 and the second-layer magnet holes 322, "radially outward" or "radially inward" refers to the positional relationship when compared at the point where a common line segment passing through the rotation axis 12 intersects, as viewed axially. This also applies to the positional relationship between the first portion 3211 and the first-layer magnet holes 321, described later.

[0048] Like the first-layer magnet holes 321, the second-layer magnet holes 322 are formed in pairs symmetrically about the d-axis. Furthermore, the second-layer magnet holes 322 on either side of the d-axis extend circumferentially wider than the first-layer magnet holes 321 on either side of the d-axis. A magnet piece 62 is positioned above each of the second-layer magnet holes 322. Furthermore, gaps are provided between the second-layer magnet holes 322 and the magnet piece 62 at both ends of the magnet piece 62 in the longitudinal direction. These gaps can be hollow or filled with resin, for example.

[0049] In this embodiment, two second-layer magnet holes 322 are formed on one side of the d-axis in the circumferential direction, and two are formed on the other side of the d-axis in the circumferential direction. That is, a total of four second-layer magnet holes 322 are formed for one magnetic pole.

[0050] The rotor core 32 has the first and second magnet holes 321 and 322 , and thus has three portions 3211 , 3212 , and 3213 (hereinafter also referred to as a first portion 3211 , a second portion 3212 , and a third portion 3213 ) connected in the radial direction only via bridge portions.

[0051] Specifically, the first portion 3211 extends radially outward relative to the first layer of magnet holes 321. The first portion 3211 forms a portion 328A of the outer peripheral surface 328 of the rotor core 32 (see Figure 3 The first portion 3211 forms the q axis (at Figure 4 Specifically, the q-axis magnetic flux of the first portion 3211 flows from one circumferential end of the first portion 3211 toward the other circumferential end through the first portion 3211 (the region radially outward of the first layer's magnet holes 3212).

[0052] The second portion 3212 passes between the second layer magnet holes 322 and the first layer magnet holes 321 and extends to the outer peripheral surface 328 of the rotor core 32 on both sides of the circumference. The second portion 3212 forms a portion 328B of the outer peripheral surface 328 of the rotor core 32 (hereinafter also referred to as "the outer peripheral surface portion 328B of the second portion 3212") on both sides of the circumference of the first portion 3211 (see Figure 3 The second portion 3212 forms a magnetic path for the q-axis magnetic flux. Specifically, the q-axis magnetic flux of the second portion 3212 flows from one end of the second portion 3212 (one outer peripheral surface 328B) toward the other end (the other outer peripheral surface 328B) through the second-layer magnet holes 322 and the first-layer magnet holes 321.

[0053] The third portion 3213 passes through the radially inner side of the second layer of magnet holes 322 and extends to the outer peripheral surface 328 of the rotor core 32 on both circumferential sides. The third portion 3213 forms a portion 328C of the outer peripheral surface 328 of the rotor core 32 on both circumferential sides of the second portion 3212 (see FIG. Figure 3 ).

[0054] In addition, in this embodiment, the mass of the third portion 3213 may be significantly greater than the mass of the second portion 3212 , and the mass of the second portion 3212 may be significantly greater than the mass of the first portion 3211 .

[0055] Furthermore, the rotor core 32 includes the three portions 3211 , 3212 , and 3213 , thereby including a plurality of bridge portions 41 , 42 , 43 , 44 , and 45 connecting the three portions 3211 , 3212 , and 3213 .

[0056] The bridge portion 41 (hereinafter referred to as the "first bridge portion 41") supports the first portion 3211 radially outwardly from the second portion 3212. Specifically, the first bridge portion 41 connects the second portion 3212 to the first portion 3211 and extends circumferentially. The first bridge portions 41 are provided in pairs on both circumferential sides (circumferentially outward) of the first portion 3211.

[0057] The bridge portion 42 (hereinafter referred to as the "second bridge portion 42") supports the second portion 3212 radially outwardly from the third portion 3213. Specifically, the second bridge portion 42 connects the third portion 3213 to the second portion 3212 and extends circumferentially. The second bridge portions 42 are provided in pairs on both circumferential sides (circumferentially outward) of the second portion 3212.

[0058] The bridge portion 43 (hereinafter referred to as “first center bridge portion 43 ”) supports the first site 3211 on the second site 3212 along the d-axis.

[0059] The bridge portion 44 (hereinafter referred to as “second center bridge portion 44 ”) supports the second site 3212 on the third site 3213 along the d-axis.

[0060] The bridge portion 45 (hereinafter referred to as “second intermediate bridge portion 45 ”) supports the second portion 3212 on the third portion 3213 between the two second-layer magnet holes 322 .

[0061] exist Figure 3 In the illustrated example, the magnet pieces 61 inserted into the first-layer magnet holes 321 form the first-layer permanent magnets from the radially outer side (an example of the first-layer permanent magnets), and the magnet pieces 62 inserted into the second-layer magnet holes 322 form the second-layer permanent magnets from the radially outer side (an example of the second-layer permanent magnets). Furthermore, in this embodiment, a single magnet piece (either magnet piece 61 or magnet piece 62) is inserted into each magnet hole (the first-layer magnet hole 321 or the second-layer magnet hole 322). However, in a modified example, two or more magnet pieces may be inserted into each magnet hole.

[0062] In addition, Figure 3 In the illustrated example, neither the first-layer magnet holes 321 nor the second-layer magnet holes 322 extend along the d-axis, but rather have first and second center bridge portions 43 and 44 along the d-axis. However, in a modified embodiment, either or both of the first-layer magnet holes 321 and the second-layer magnet holes 322 may extend along the d-axis.

[0063] In addition, Figure 3 In the illustrated example, the magnet pieces 61 and 62 do not extend on the d-axis, similar to the first-layer magnet holes 321 and the second-layer magnet holes 322 . However, only one of them may extend on the d-axis.

[0064] Next, refer to Figure 4 The following drawings illustrate the characteristic structure of this embodiment. Figure 4 yes Figure 3 The further enlarged view of the part is a line diagram for explaining the shape characteristics. In the following, in order to distinguish between the circumferential outer and circumferential inner second layer magnet holes 322, the magnet piece 62 inserted into the circumferential inner second layer magnet hole 322 is sometimes also referred to as the circumferential inner magnet piece 62 (in Figure 3 The magnet piece 62 inserted into the magnet hole 322 of the second layer on the circumferential outer side is also referred to as the magnet piece 62 on the circumferential outer side (in Figure 3 etc. is represented as magnet piece 62-2).

[0065] In this embodiment, if Figure 4 As shown, the corners are connected (refer to Figure 4 P3) and the center of the rotor core 32 (refer to Figure 2 The angle γ on the acute angle side formed by the line segment L20 of the rotation axis 12) and the d-axis is preferably within the range of 12° to 20°. The corner of the angle γ refers to the corner of the magnet piece 62-2 on the circumferential outer side of the two magnet pieces 62, that is, the corner on the d-axis side and radially outward of the four corners of the magnet piece 62-2.

[0066] In this embodiment, if Figure 4 As shown, when viewed in the axial direction, the magnet angle of the circumferentially inner magnet piece 61 (hereinafter also referred to as the "first magnet angle α") is defined as the angle formed by the reference line L1 and the extension direction L11 of the magnet piece 61. The extension direction L11 of the magnet piece 61 corresponds to the extension direction of the radially outer side surface (the side surface in the main magnetic flux direction) 619 of the magnet piece 61 when viewed in the axial direction. In addition, the reference line L1 corresponds to the line segment extending from the intersection P1 of the extension direction of the magnet piece 61 and the d-axis in a direction perpendicular to the d-axis when viewed in the axial direction. Moreover, the first magnet angle α is defined as the positive side on the radially inner side of the reference line L1 when viewed in the axial direction.

[0067] In addition, in this embodiment, the magnet angle of the circumferentially inner magnet piece 62-1 (hereinafter also referred to as the "second magnet angle β") is defined as the angle formed by the reference line L2 and the extension direction L12 of the circumferentially inner magnet piece 62-1 when viewed in the axial direction. The extension direction L12 of the magnet piece 62 corresponds to the extension direction of the radially outward side surface (the side surface in the main magnetic flux direction) 629 of the magnet piece 62 when viewed in the axial direction. In addition, the reference line L2 corresponds to the line segment extending from the intersection P2 of the extension direction of the magnet piece 62 and the d-axis in a direction perpendicular to the d-axis when viewed in the axial direction. Then, the second magnet angle β is defined as the positive side of the side radially inward of the reference line L2 when viewed in the axial direction.

[0068] In this embodiment, the first magnet angle α and the second magnet angle β have a relationship of first magnet angle α < second magnet angle β.

[0069] Then, as a comparative example, when the first magnet angle α = the second magnet angle β and the second magnet angle β>0, as described in "Problems to be Solved by the Invention", there is a region in which the q-axis magnetic path of the first portion 3211 is near the d-axis (see Figure 4 This problem is that the Q5 portion of the second magnet is narrowed and the reluctance torque cannot be effectively utilized. This problem is more noticeable when the second magnet angle β is relatively large.

[0070] On the other hand, according to this embodiment, the reluctance torque is effectively utilized by having the relationship of the first magnet angle α < the second magnet angle β. Figure 5 As will be described in the following figures, it is possible to improve the reluctance torque without significantly increasing or reducing the back electromotive force.

[0071] In addition, in this embodiment, since the first magnet angle α is smaller than the second magnet angle β, for example, in the region near the d-axis of the second portion 3212 (see Figure 4The q-axis magnetic path width in the Q6 portion) is easily narrowed, but the disadvantages caused by this can be substantially eliminated. In other words, if LQ6 is reduced within the range where magnetic saturation occurs in the Q4 portion (that is, the range where magnetic saturation does not occur in the Q6 portion), it is easy to make LQ5 larger by the amount that LQ6 is reduced. Therefore, it is possible to increase the reluctance torque of the first portion 3211 without reducing the reluctance torque of the second portion 3212. Here, when viewed in the axial direction, LQ4 (an example of the second distance) is the shortest distance between the magnet piece 61 and the circumferentially outer magnet piece 62-2. In the example shown in the figure, it is the shortest distance between the radially inner corner of the magnet piece 61 and the q-axis side and the magnet piece 62-2. In addition, when viewed in the axial direction, LQ6 (an example of the first distance) is the distance between the intersection P4 on the d-axis of the straight line L44 along the radially inner side of the magnet piece 61 and the above-mentioned intersection P2. At this time, it is preferred that LQ6 < LQ4. Furthermore, when viewed in the axial direction, LQ5 is the shortest distance between the intersection point P1 and the outer peripheral surface of the rotor core 32. Furthermore, in the example shown in the figure, LQ5<LQ6.

[0072] In addition, in other embodiments, the Figure 4 The structure in which the Q4A portion of the Q4 portion is located radially inward (closer to the d-axis) produces magnetic saturation is replaced by Figure 4 In this case, for example, the distance between the magnet hole 321 and the magnet hole 322 where the magnet piece 62-2 is disposed is greater than the distance between the corners of the magnet piece 62-2 (see Figure 4 The portion with the smallest distance to the radial inner side of P3) may correspond to the portion where magnetic saturation occurs in the second portion 3212. Therefore, in this case, the above-mentioned LQ4 may be the portion with the smallest distance between the magnet hole 321 and the magnet hole 322 where the magnet piece 62-2 is arranged, that is, the portion closer to the corner of the magnet piece 62-2 (see Figure 4 The minimum distance radially inward of P3 is defined as the minimum distance radially inward. Furthermore, in this configuration, the magnet hole 322 in which the magnet piece 62-2 is located can have a radially outwardly extending portion (not shown) at the end portion on the side closest to the d-axis (i.e., the end portion on the side of the second intermediate bridge portion 45). This extending portion can define the minimum distance associated with LQ4. In this case, LQ6 is preferably less than LQ4.

[0073] Figures 5 to 9 This is an explanatory diagram of the effects of this embodiment based on the analysis results.

[0074] Figure 5 The horizontal axis represents the difference between the first magnet angle α and the second magnet angle β (=α-β), and the vertical axis represents the difference between the q-axis inductance Lq and the d-axis inductance Ld (=Lq-Ld). The values ​​increase as you go up the vertical axis. Figure 5In the figure, the drawing point of the shape corresponding to β=10 is the drawing point when the second magnet angle β=10°, the drawing point of the shape corresponding to β=5 is the drawing point when the second magnet angle β=5°, and the drawing point of the shape corresponding to β=0 is the drawing point when the second magnet angle β=0°.

[0075] The greater the difference between the q-axis inductance Lq and the d-axis inductance Ld (= Lq - Ld), the higher the reluctance torque. Figure 5 It can be seen that the smaller α-β is at the beginning, the higher the reluctance torque is.

[0076] In this regard, in this embodiment, as described above, since the relationship of first magnet angle α < second magnet angle β is established, α - β is less than 0. Therefore, according to this embodiment, at the same second magnet angle β, the reluctance torque is improved compared to a case where the relationship of first magnet angle α < second magnet angle β is not established.

[0077] In the relationship of the first magnet angle α < the second magnet angle β, the difference (=α-β) is preferably -1° or less, more preferably -2° or less, and even more preferably -5° or less. Figure 5 It can be seen that the reluctance torque can be effectively improved.

[0078] Here, if the second magnet angle β is less than 0°, the width of the second portion 3212 along the d-axis tends to increase, and the mass of the second portion 3212 tends to increase. The increased mass of the second portion 3212 tends to hinder the high rotation speed of the motor 1 due to centrifugal force. Therefore, in this embodiment, the second magnet angle β is preferably greater than 0°. This allows for higher rotation speeds of the motor 1 and improves the reluctance torque.

[0079] Furthermore, when the second magnet angle β is greater than 0°, the second-layer magnet holes 322 (and the associated magnet pieces 62 within the second-layer magnet holes 322) form a W-shaped configuration centered on the d-axis. Specifically, the portion of the second-layer magnet holes 322 on the side closer to the d-axis (the portion inserted into the circumferentially inner magnet piece 62-1) forms a convex shape radially outward with the d-axis as the center, while the portion farther from the d-axis (the portion inserted into the circumferentially outer magnet piece 62-2) forms a convex shape radially inward, combined with the portion closer to the d-axis.

[0080] Figure 6 The horizontal axis represents the first magnet angle α, and the vertical axis represents the distribution of each plot when the back electromotive force is shown. Furthermore, the value increases as the vertical axis goes up. Figure 6Each plotted point shows the analysis result when the first magnet angle α is changed while the second magnet angle β = 10°. Figure 6 It can be seen that even when the first magnet angle α is 9° or less, the back electromotive force does not increase significantly.

[0081] Figure 7 The horizontal axis represents the first magnet angle α, and the vertical axis represents the distribution of each plot at the time of the maximum torque of the motor 1. The value increases as the vertical axis goes up. Figure 7 Each plotted point shows the analysis result when the first magnet angle α is changed while the second magnet angle β is 10°. Figure 7 It can be seen that the smaller the first magnet angle α is, the more significantly the maximum torque increases.

[0082] Figure 8 The horizontal axis represents the second magnet angle β, and the vertical axis represents the distribution of each plot. Furthermore, the value increases as the vertical axis goes up. Figure 8 Each plotted point shows the analysis result when the second magnet angle β is changed while the first magnet angle α=8°. Figure 8 It can be seen that the further the second magnet angle β is from 0°, the lower the back electromotive force becomes. In addition, it can be seen that the back electromotive force decreases significantly in the region where the second magnet angle β is greater than 9°.

[0083] Figure 9 The horizontal axis represents the second magnet angle β, and the vertical axis represents the distribution of each plot at the time of maximum torque of the motor 1. The value increases as the vertical axis goes up. Figure 9 Each plotted point shows the analysis result when the second magnet angle β is changed while the first magnet angle α is 8°. Figure 9 It can be seen that the maximum torque tends to be saturated near the peak value near the second magnet angle β=10°.

[0084] Here, in Figure 6 In the range of the first magnet angle α<9° (highlighted by shading), the back electromotive force does not increase significantly compared to outside this range. Figure 8 In the range of the second magnet angle β>9° (highlighted by shading), the back electromotive force is significantly reduced compared to outside this range. Therefore, by setting the first magnet angle α<9° and 9°<the second magnet angle β, the back electromotive force can be reduced.

[0085] In addition, Figure 7 In the range of the first magnet angle α<9° (emphasized by shading), the maximum torque increases compared to outside this range. Figure 9In the range of the second magnet angle β>9° (highlighted by shading), the maximum torque saturates near the peak value. Therefore, by setting the first magnet angle α<9° and the second magnet angle β>9°, the maximum torque can be increased.

[0086] Although each embodiment has been described in detail above, the present invention is not limited to the specific embodiment and various modifications and changes can be made within the scope of the claims. In addition, all or a plurality of the structural components of the above-mentioned embodiments can be combined.

[0087] For example, in the above embodiment, the magnet pieces 61 and 62 have a generally rectangular shape with straight sides when viewed axially. However, the magnet pieces 61 and 62 may also have a curved shape. In this case, the first magnet angle α or the second magnet angle β can be calculated by applying a straight line approximation to the curved shape. Furthermore, in this case, the magnet pieces 61 and 62 that have a curved shape when viewed axially may also be bonded magnets.

[0088] Description of reference numerals:

[0089] 30: Rotor (rotor for rotating electric machine), 32: Rotor core, 3211: First part, 3212: Second part, 3213: Third part, 321: Magnet hole of the first layer, 322: Magnet hole of the second layer, 61: Magnet sheet (permanent magnet of the first layer, first magnet sheet), 62: Magnet sheet (permanent magnet of the second layer), 62-1: Magnet sheet (second magnet sheet), 62-2: Magnet sheet (third magnet sheet).

Claims

1. A rotor for a rotating electrical machine, in, include: The rotor core is formed with a first layer of magnet holes, the magnet holes of the first layer being symmetrical with respect to the d-axis when viewed in the axial direction, and a second layer of magnet holes, the magnet holes of the second layer being radially inward of the magnet holes of the first layer and symmetrical with respect to the d-axis when viewed in the axial direction; The permanent magnets of the first layer are disposed in the magnet holes of the first layer; and The second layer of permanent magnets is disposed in the magnet holes of the second layer; The rotor core includes: a first portion located radially outward of the magnet holes of the first layer and forming an outer peripheral surface of the rotor core; a second portion passing between the magnet holes of the first layer and the magnet holes of the second layer and extending circumferentially to the outer peripheral surface of the rotor core; and a third portion passing radially inward of the magnet holes of the second layer and extending circumferentially to the outer peripheral surface of the rotor core. When the magnet angle of a magnet piece is defined as the angle formed by a reference line extending in a direction perpendicular to the d-axis from the intersection of the extension direction of the side surface in the main magnetic flux direction of the magnet piece and the d-axis when viewed in the axial direction, and the extension direction of the side surface, and the side radially inward of the reference line when viewed in the axial direction is defined as the positive side of the magnet angle, The first magnet angle of the first magnet piece forming the first layer of permanent magnets and located on or closest to the d-axis is smaller than the second magnet angle of the second magnet piece forming the second layer of permanent magnets and located on or closest to the d-axis.

2. The rotor for a rotating electrical machine according to claim 1, wherein: The second magnet angle is positive and the first magnet angle is negative.

3. The rotor for a rotating electrical machine according to claim 1, wherein: The second magnet angle is greater than the first magnet angle by at least 1 degree.

4. The rotor for a rotating electrical machine according to claim 1, wherein: The first magnet angle is less than 9 degrees, and the second magnet angle is greater than 9 degrees.

5. The rotor for a rotating electrical machine according to any one of claims 1 to 4, wherein: The angle formed by the acute angle between the d-axis and the line segment connecting the d-axis side and radially outer corner of the third magnet piece closest to the q-axis of the permanent magnet forming the second layer and the center of the rotor core is within the range of greater than 12 degrees and less than 20 degrees.

6. The rotor for a rotating electrical machine according to claim 5, wherein: In the distance involved in the second part, The distance between the intersection point on the d-axis of a straight line along the radially inner side of the first magnet piece and the intersection point on the d-axis of a straight line along the radially outer side of the second magnet piece when viewed in the axial direction is set as a first distance, and The shortest distance between the first magnet piece and the third magnet piece when viewed in the axial direction, or the shortest distance between the magnet holes of the first layer where the first magnet piece is arranged and the magnet holes of the second layer where the third magnet piece is arranged, that is, the shortest distance radially inward of the corner portion is set as the second distance, The second distance is greater than the first distance.

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