rotating electrical machines

Abstract

To provide a rotary electric machine in which torque ripple can be reduced.SOLUTION: In a rotor 20, a plurality of magnetic pole parts 26 each including a permanent magnet 23 and an outer core portion 25 is formed at equal angle intervals in a circumferential direction. The plurality of magnetic pole parts 26 includes slits 27 which are formed in a rotor core 22, one by one. The plurality of slits 27 includes a first slit 27a and a second slit 27b. The first slit 27a is disposed in a third area C or a sixth area F. The second slit 27n is disposed in any one of a first area A, a second area B, the third area C, a fourth area D, a fifth area E and the sixth area F.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a rotating electric machine. [Background technology]

[0002] Among rotating electrical machines, embedded magnet rotors, in which permanent magnets are embedded inside the rotor core, are well known. In embedded magnet rotors, multiple magnetic poles, each including a permanent magnet and a portion of the rotor core, are formed in the circumferential direction. The rotor is configured to obtain reluctance torque from a portion of the rotor core in addition to magnetic torque from the permanent magnets. For example, in the embedded magnet rotor described in Patent Document 1, the magnetic poles have slits formed in the rotor core. The action of these slits makes it possible to reduce torque ripple. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-285845 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have been studying the arrangement of slits in the rotor described above that can more suitably reduce torque ripple. An object of the present disclosure is to provide a rotating electric machine capable of reducing torque ripple. [Means for solving the problem]

[0005] A rotating electric machine that solves the above problem includes a rotor (20) having a rotor core (22) and permanent magnets (23) embedded in the rotor core, and a stator (10) that applies a rotating magnetic field to the rotor, wherein the rotor has a plurality of magnetic pole portions (26) formed at equal angular intervals in the circumferential direction, each of the plurality of magnetic pole portions having one slit (27) formed in the rotor core, and the number of the magnetic pole portions is P, and the angle from one circumferential end (26a) to the other circumferential end (26b) of each of the magnetic pole portions is 360° / P, and the circumferential When the area from one end of the circumference to the other end of the circumference is equally divided into 12 areas, the 4th to 9th areas counted in order from the one end of the circumference are respectively the first area (A), the second area (B), the third area (C), the fourth area (D), the fifth area (E), and the sixth area (F), and the plurality of slits include a first slit (27a) and a second slit (27b), the first slit is arranged in the third area or the sixth area, and the second slit is arranged in any of the first area, the second area, the third area, the fourth area, the fifth area, and the sixth area.

[0006] With this configuration, the phase width of the torque ripple when the position of the slit is changed in the circumferential direction is larger in the third and sixth areas than in the other areas (see FIG. 6). Therefore, by including a first slit arranged in the third or sixth area among the multiple slits, it is possible to improve the degree of freedom in setting the position of the second slit, which generates torque ripple of an opposite phase to that of the first slit. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a configuration diagram of a rotating electric machine according to an embodiment; [Figure 2] FIG. 2 is a partial plan view showing a part of the rotor in the embodiment. [Figure 3] FIG. 2 is a partial plan view showing a part of the rotor in the embodiment. [Figure 4] 10 is an explanatory diagram for explaining the positioning of slits in the rotor of the same embodiment. FIG. [Figure 5] 10 is an explanatory diagram for explaining the positioning of slits in the rotor of the same embodiment. FIG. [Figure 6] 6 is a graph for explaining the positioning of slits in the rotor of the same configuration. [Figure 7] 6 is a graph for explaining the positioning of slits in the rotor of the same configuration. [Figure 8] 10A and 10B are explanatory diagrams for explaining various patterns of slit arrangement and the magnitude of the effect of each pattern in the embodiment. [Figure 9] 10 is an explanatory diagram for explaining the positioning of slits in the rotor of the same embodiment. FIG. [Figure 10] 10 is an explanatory diagram for explaining the positioning of slits in the rotor of the same embodiment. FIG. [Figure 11] 10 is an explanatory diagram for explaining the positioning of slits in the rotor of the same embodiment. FIG. [Figure 12] FIG. 10 is an explanatory diagram for explaining a rotor of a modified example. [Figure 13] FIG. 10 is a perspective view of the rotor of the modified example. [Figure 14] FIG. 10 is an explanatory diagram for explaining a rotor of a modified example. [Figure 15] FIG. 10 is a perspective view of the rotor of the modified example. [Figure 16] FIG. 10 is a perspective view of a rotor according to a modified example. [Figure 17] FIG. 10 is a plan view of a rotor according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of a rotating electrical machine will be described below. 1 is configured as an embedded magnet brushless motor. The rotating electric machine M includes a substantially annular stator 10 and a substantially cylindrical rotor 20 rotatably disposed in a radially inner space of the stator 10. The stator 10 applies a rotating magnetic field to the rotor 20.

[0009] (Configuration of stator 10) The stator 10 includes a substantially annular stator core 11. The stator core 11 is made of a magnetic metal material. The stator core 11 is formed, for example, by stacking a plurality of electromagnetic steel plates in the direction of the axis L1. The stator core 11 has twelve teeth 12 in this embodiment that extend radially inward and are arranged at equal intervals in the circumferential direction. That is, the stator 10 in this embodiment has twelve slots. The teeth 12 have the same shape. The radially inner end portions, which are the tips, are substantially T-shaped, and the tip surfaces 12a are arc-shaped following the outer peripheral surface of the rotor 20.

[0010] Windings 13 are wound around teeth 12, for example, by concentrated winding. Windings 13 are connected in three phases, and function as U-phase, V-phase, and W-phase, respectively, as shown in FIG. 1. When power is supplied to windings 13, a rotating magnetic field is generated in stator 10 to rotate rotor 20. In this stator 10, the outer peripheral surface of stator core 11 is fixed to the inner peripheral surface of housing 14.

[0011] (Configuration of rotor 20) The rotor 20 includes a rotating shaft 21, a substantially cylindrical rotor core 22 into whose center the rotating shaft 21 is fitted, and eight permanent magnets 23 in this embodiment that are embedded inside the rotor core 22.

[0012] The rotor core 22 is made of a magnetic metal material and is formed, for example, by stacking a plurality of electromagnetic steel plates in the direction of the axis L1. The rotor 20 is rotatably disposed relative to the stator 10 with the rotating shaft 21 supported by a bearing (not shown) provided in the housing 14.

[0013] The rotor core 22 has magnet accommodating holes 24 for accommodating the permanent magnets 23. In this embodiment, eight magnet accommodating holes 24 are provided at equal intervals around the circumferential direction of the rotor core 22. Each magnet accommodating hole 24 has a substantially V-shaped folded shape that protrudes radially inward, and is identical to each other. The magnet accommodating holes 24 are provided over the entire axial direction of the rotor core 22.

[0014] Here, the permanent magnet 23 of this embodiment is a bonded magnet made by molding and solidifying a magnetic material made by mixing magnetic powder with resin. That is, the permanent magnet 23 is formed by using the magnet accommodating hole 24 of the rotor core 22 as a molding die, filling the magnet accommodating hole 24 with unsolidified magnetic material by injection molding without gaps, and then solidifying it inside the magnet accommodating hole 24 after filling. Therefore, the hole shape of the magnet accommodating hole 24 becomes the outer shape of the permanent magnet 23. The magnetic powder used for the permanent magnet 23 of this embodiment is, for example, a samarium iron nitrogen (SmFeN) magnet, but other rare earth magnets, etc. may also be used.

[0015] After the magnetic material has solidified, the permanent magnets 23 provided in the magnet accommodating holes 24 of the rotor core 22 are magnetized from the outside of the rotor core 22 using a magnetizing device (not shown) so that the permanent magnets function as their intended magnets. In this embodiment, eight permanent magnets 23 are provided circumferentially around the rotor core 22, and are magnetized so that the polarities are alternately opposite in the circumferential direction. Each permanent magnet 23 is also magnetized in its thickness direction.

[0016] Each permanent magnet 23 has a generally V-shaped folded shape that protrudes radially inward. More specifically, as shown in Fig. 2, each permanent magnet 23 has a shape in which radially inner ends of a pair of straight portions 23a are connected by a bent portion 23b. A radially outer end 23c of each straight portion 23a is located near the outer peripheral surface 22a of the rotor core 22.

[0017] The permanent magnets 23 are symmetrical with respect to their own circumferential center line Ls, which passes through the axis L1 of the rotor 20. The permanent magnets 23 are also close to the magnetic pole boundary line Ld between circumferentially adjacent permanent magnets 23. When viewed from the axis L1 direction, the magnetic pole boundary line Ld is a straight line that separates each magnetic pole portion 26, which will be described later, and is a straight line that is perpendicular to the axis L1.

[0018] The magnetic pole pitch Lp is the distance between the intersection of the extension of the inner surface of each straight portion 23a of the V-shaped permanent magnet 23 and the outer peripheral surface 22a of the rotor core 22, and the embedding depth Lm is the distance from the outer peripheral surface 22a of the rotor core 22 to the inner surface of the bent portion 23b on the circumferential center line Ls of the permanent magnet 23. The permanent magnet 23 of this embodiment is configured to have a deep folded shape such that the embedding depth Lm is greater than the magnetic pole pitch Lp. In other words, the magnet surface 23d of the permanent magnet 23 of this embodiment, formed by the inner surfaces of each straight portion 23a and the bent portion 23b, is configured to be larger than the magnet surface of a known surface magnet (not shown). Furthermore, by setting the embedding depth Lm to be large, the bent portion 23b of the permanent magnet 23 is located radially inward and closer to the shaft insertion hole 22b at the center of the rotor core 22, into which the rotating shaft 21 is inserted. This folded shape of the permanent magnet 23 is just one example, and it can be changed as appropriate, such as one with a shallower embedding depth Lm or one with a roughly U-shaped folded shape with a larger bent portion 23b. Because the permanent magnet 23 has a roughly V-shaped folded shape that protrudes radially inward, the area in the radial direction where the permanent magnet 23 is provided can be made wider than in the surface magnet type rotor described above.

[0019] A portion of rotor core 22 located inside the V-shaped folded shape of permanent magnet 23 and radially outward of permanent magnet 23 functions as an outer core portion 25 that faces stator 10 and generates reluctance torque. Outer core portion 25 has a substantially triangular shape with one vertex facing toward the center of rotor 20 when viewed in the axial direction.

[0020] The rotor 20 has a plurality of magnetic pole portions 26 arranged in the circumferential direction. Each of the plurality of magnetic pole portions 26 includes one permanent magnet 23 and an outer core portion 25 surrounded by the inside of the V-shape of the permanent magnet 23. The plurality of magnetic pole portions 26 are formed at equal angular intervals in the circumferential direction.

[0021] Each magnetic pole portion 26 has a first end 26a, which is one circumferential end of the magnetic pole portion 26, and a second end 26b, which is the other circumferential end of the magnetic pole portion 26. The positions of the first end 26a and the second end 26b in the circumferential direction each coincide with the magnetic pole boundary line Ld. Note that, when the counterclockwise direction is the forward rotation direction and the clockwise direction is the reverse rotation direction in the drawing, the end of each magnetic pole portion 26 on the front side in the forward rotation direction is the second end 26b, and the end on the rear side in the forward rotation direction is the first end 26a.

[0022] In each magnetic pole portion 26, the magnetic pole opening angle θm, which is the angle from the first end 26a to the second end 26b around the axis L1, is 360° / P, where P is the number of magnetic poles of the rotor 20, i.e., the number of magnetic pole portions 26. In the rotor 20 of this embodiment, the number of magnetic pole portions 26 is eight. Therefore, the magnetic pole opening angle θm in each magnetic pole portion 26 is 45°. The magnetic pole portions 26 function as north and south poles alternately in the circumferential direction, as shown in FIG. 1. A rotor 20 having such magnetic pole portions 26 can preferably generate magnet torque and reluctance torque.

[0023] As shown in FIG. 3, an air gap Lg is defined between the outer peripheral surface 22a of the rotor core 22 and the tip surfaces 12a of the teeth 12. The magnetic pole pitch Lp is set to satisfy the relationship Lt-(Lg×2)≦Lp≦Lt+(Lg×2), where Lt is the width of the tip surfaces 12a of the teeth 12. The width Lt of the tip surfaces 12a of the teeth 12 is the width of the tip surfaces 12a in the directions perpendicular to both the axial and radial directions. By setting the magnetic pole pitch Lp within the above range, it is possible to make the magnetic pole pitch Lp approximately equal to the size of the tip surfaces 12a of the teeth 12. As a result, it is possible to efficiently obtain rotational torque of the rotor 20.

[0024] (Configuration of slit 27) As shown in FIG. 1 , each of the multiple magnetic pole portions 26 has one slit 27 formed in the outer core portion 25. Each of the multiple magnetic pole portions 26 has one slit 27 formed in the outer surface of the outer core portion 25. The slits 27 are, for example, groove-shaped and formed in the outer surface of the outer core portion 25. That is, the slits 27 are formed so as to be recessed radially inward from the outer surface of the outer core portion 25. The outer surface of the outer core portion 25 is part of the outer peripheral surface 22a of the rotor core 22. The slits 27 are, for example, formed linearly along the axis L1.

[0025] (Regarding the positioning of the slits 27 in each magnetic pole portion 26) As shown in FIG. 4, six areas are set in each magnetic pole portion 26, aligned in the circumferential direction. Specifically, the magnetic pole portion 26 is divided into 12 equal areas in the circumferential direction. Counting these 12 areas in order from the first end 26a in the forward direction, the fourth to ninth areas are designated as the first area A, the second area B, the third area C, the fourth area D, the fifth area E, and the sixth area F, respectively. The opening angle of each of the areas A to F about the axis L1 is the angle obtained by dividing the magnetic pole opening angle θm into 12 equal parts, which is 3.75° in this embodiment. The first area A to the sixth area F are set, for example, within the range of the magnetic pole pitch Lp.

[0026] In each magnetic pole portion 26, the slits 27 are set so that the circumferential center Lc of the slits 27 is located in one of the areas A to F. In the example shown in FIG. 4, one example of one slit 27 provided in the magnetic pole portion 26 is indicated by a two-dot chain line. The slit 27 is provided so that its circumferential center Lc is located in the third area C. Note that, for the sake of convenience of explanation, in the following, when the circumferential center Lc of each slit 27 is located in one of the areas A to F, the description will be omitted and it will be simply stated that "the slit 27 is arranged in an area."

[0027] FIG. 5 shows an example of the arrangement of the slits 27 in each magnetic pole portion 26. As shown in the figure, the eight slits 27 provided in each of the eight magnetic pole portions 26 include at least one first slit 27a and at least one second slit 27b. The first slits 27a are slits 27 arranged in the third area C or slits 27 arranged in the sixth area F. The second slits 27b are arranged in any of the first area A, second area B, third area C, fourth area D, fifth area E, and sixth area F. In FIG. 5, the outer periphery of each magnetic pole portion 26 is marked with the symbol indicating the arrangement area of ​​the slits 27.

[0028] As shown in the figure, the number of slits 27 arranged in the first area A is two. The number of slits 27 arranged in the second area B is zero. The number of slits 27 arranged in the third area C is one. The number of slits 27 arranged in the fourth area D is two. The number of slits 27 arranged in the fifth area E is zero. And the number of slits 27 arranged in the sixth area F is three. The slits 27 are arranged in the following order in the forward rotation direction (counterclockwise direction) from the slit 27 of the upper magnetic pole portion 26 in FIG. 5: the first area A, the third area C, the fourth area D, the sixth area F, the first area A, the fourth area D, the sixth area F, and the sixth area F. The order of the arrangement areas of the slits 27 in the circumferential direction is not limited to this embodiment and can be changed as appropriate. In the configuration shown in FIG. 5, there are areas in each of the areas A to F where no slits 27 are arranged. In this example, the areas where no slits 27 are arranged are the second area B and the fifth area E.

[0029] (24th order torque ripple) The second slits 27b are disposed at a position where they generate torque ripples that are in the opposite phase to the torque ripples of the (3×P)th order of rotation generated by the first slits 27a. In the rotor 20 of this embodiment, the number P of magnetic poles is 8. Therefore, the second slits 27b are disposed at a position where they generate torque ripples that are in the opposite phase to the torque ripples of the 24th order of rotation generated by the first slits 27a.

[0030] The graph in FIG. 6 shows the relationship between the position of the slit 27 and the phase of the torque ripple of the 24th-order rotation component. As shown in the figure, the phase width when the position of the slit 27 is changed from one end of the first area A to the other is approximately 75°, from approximately 195° to approximately 270°. The phase width when the position of the slit 27 is changed from one end of the second area B to the other is approximately 60°, from approximately 270° to approximately 330°. The phase width when the position of the slit 27 is changed from one end of the third area C to the other is approximately 210°, from approximately 330° to approximately 180°. The phase width when the position of the slit 27 is changed from one end of the fourth area D to the other is approximately 50°, from approximately 180° to approximately 230°. The phase width when the position of the slit 27 is changed from one end of the fifth area E to the other is approximately 80°, from approximately 230° to approximately 310°. The phase width when the position of slit 27 is changed from one end of sixth area F to the other is approximately 125°, which is between approximately 310° and approximately 75°. As described above, of areas A to F, only the third area C and sixth area F have a phase width exceeding 90° when the position of slit 27 is changed within the range.

[0031] The second slits 27b are positioned to generate torque ripple that is in opposite phase to the 24th-order rotation torque ripple generated by the first slits 27a, i.e., with a phase difference of 180°. This causes the 24th-order rotation torque ripples generated by the first slits 27a and the second slits 27b to interfere with each other and weaken each other. As a result, it is possible to keep the 24th-order rotation torque ripple small.

[0032] For example, as shown in FIG. 6, assume that the first slit 27a is disposed at a first position X1 in the third area C in one of the magnetic pole portions 26. The phase of the 24th-order rotational torque ripple generated by the first slit 27a disposed at the first position X1 is 60°. Therefore, the second slit 27b is set to either the second position X2 or the third position X3, where the torque ripple is generated with a phase difference of 180° from 60°, i.e., a phase of 240°. The second position X2 is a position within the first area A, and the third position X3 is a position within the fifth area E. In this way, the positions of the first slit 27a and the second slit 27b are set so that the torque ripple of the 24th-order rotational torque ripple is generated in opposite phases to each other.

[0033] The third area C and the sixth area F have a phase width of 90° or more, which is wider than the other areas. Therefore, by configuring at least one of the slits 27 of each magnetic pole portion 26 as the first slit 27a located in the third area C or the sixth area F, it is possible to improve the degree of freedom in setting the position of the second slit 27b that generates torque ripple in the opposite phase to the first slit 27a.

[0034] (48th order torque ripple) Furthermore, the second slits 27b are positioned to generate torque ripples that are opposite in phase to the (6×P)-th order torque ripple generated by the first slits 27a. In the rotor 20 of this embodiment, the number of magnetic poles P is 8. Therefore, the second slits 27b are positioned to generate torque ripples that are opposite in phase to the 48th order torque ripple generated by the first slits 27a. This causes the 48th order torque ripples generated by the first slits 27a and the second slits 27b to interfere with each other and weaken each other. As a result, it is possible to minimize the 48th order torque ripple.

[0035] The graph in Fig. 7 shows the relationship between the position of slit 27 and the phase of the torque ripple of the 48th rotational order component. As shown in the figure, in each of the first area A, the third area C, and the fifth area E, the phase width when the position of slit 27 is changed from one end of the area to the other is approximately 180°, from approximately 0° to approximately 180°. Also, in each of the second area B, the fourth area D, and the sixth area F, the phase width when the position of slit 27 is changed from one end of the area to the other is approximately 180°, from approximately 180° to approximately 360°.

[0036] Therefore, the second slits 27b that generate a torque ripple of the 48th rotational order component in the opposite phase to the first slits 27a that are arranged in the third area C are arranged in any one of the second area B, the fourth area D, and the sixth area F. In addition, the second slits 27b that generate a torque ripple of the 48th rotational order component in the opposite phase to the first slits 27a that are arranged in the sixth area F are arranged in any one of the first area A, the third area C, and the fifth area E.

[0037] The table in Fig. 8 illustrates 22 patterns for the arrangement of slits 27 in each magnetic pole portion 26 that have a significant effect on reducing torque ripple. The table also shows the number of slits 27 arranged in each of the first area A to sixth area F for each of the 22 patterns. Note that P in the table is the number of magnetic poles of the rotor 20. The number in parentheses in the table also indicates the number of slits 27 when the number of magnetic poles P of the rotor 20 is 8.

[0038] The reduction effect of each pattern in the table indicates the ratio of torque ripple reduction to a rotor with a comparative configuration, which will be described later. The rotor with the comparative configuration is configured by omitting the slits 27 from the rotor 20 of this embodiment. In other words, the rotor with the comparative configuration has a smooth, circular outer surface 22a of the rotor core 22 when viewed axially.

[0039] The arrangement pattern of the slits 27 in the rotor 20 shown in Fig. 5 is pattern 4, which is included in the 22 patterns shown in the table of Fig. 8. In pattern 4, torque ripple is reduced by 90% compared to the comparative configuration. Of the 22 patterns, pattern 4 has the greatest effect in reducing torque ripple.

[0040] As shown in FIG. 8, among the 22 patterns, patterns 3, 5, and 9 reduce torque ripple by 85% compared to the comparative configuration. Among the 22 patterns, patterns 1, 2, 10, 11, and 13 reduce torque ripple by 80% compared to the comparative configuration. Among the 22 patterns, patterns 6, 7, 8, 12, 15, 18, 19, and 20 reduce torque ripple by 75% compared to the comparative configuration. Among the 22 patterns, patterns 14, 16, and 17 reduce torque ripple by 70% compared to the comparative configuration. Among the 22 patterns, pattern 22 reduces torque ripple by 65% ​​compared to the comparative configuration. And among the 22 patterns, pattern 21 reduces torque ripple by 35% compared to the comparative configuration.

[0041] FIG. 9 shows a rotor 20 in which the slits 27 are arranged in Pattern 3. When the number of magnetic poles P of the rotor 20 is 8, in Pattern 3, the number of slits 27 arranged in the first area A is two. The number of slits 27 arranged in the second area B is zero. The number of slits 27 arranged in the third area C is two. The number of slits 27 arranged in the fourth area D is one. The number of slits 27 arranged in the fifth area E is zero. The number of slits 27 arranged in the sixth area F is three. The slits 27 are arranged in the following order in the forward rotation direction (counterclockwise direction) starting from the slit 27 of the upper magnetic pole portion 26 in FIG. 9: the first area A, the sixth area F, the third area C, the fourth area D, the sixth area F, the first area A, the sixth area F, and the third area C. The order of the arrangement areas of the slits 27 in the circumferential direction is not limited to the example shown in FIG. 9 and can be changed as appropriate.

[0042] FIG. 10 shows a rotor 20 in which the arrangement of the slits 27 is pattern 5. When the number of magnetic poles P of the rotor 20 is 8, in pattern 5, the number of slits 27 arranged in the first area A is 0. The number of slits 27 arranged in the second area B is 0. The number of slits 27 arranged in the third area C is 2. The number of slits 27 arranged in the fourth area D is 3. The number of slits 27 arranged in the fifth area E is 0. The number of slits 27 arranged in the sixth area F is 3. The slits 27 are arranged in the third area C, the sixth area F, the third area C, the fourth area D, the sixth area F, the fourth area D, the fourth area D, the sixth area F, and the sixth area F, in order from the slit 27 of the magnetic pole portion 26 at the top of FIG. 10 in the forward rotation direction (counterclockwise direction). The order of the arrangement areas of the slits 27 in the circumferential direction is not limited to the example shown in FIG. 10 and can be changed as appropriate.

[0043] FIG. 11 shows a rotor 20 in which the arrangement of the slits 27 is pattern 8. When the number of magnetic poles P of the rotor 20 is 8, in pattern 8, the number of slits 27 arranged in the first area A is two. The number of slits 27 arranged in the second area B is two. The number of slits 27 arranged in the third area C is two. The number of slits 27 arranged in the fourth area D is zero. The number of slits 27 arranged in the fifth area E is zero. And the number of slits 27 arranged in the sixth area F is two. The slits 27 are arranged in the first area A, the third area C, the sixth area F, the second area B, the first area A, the third area C, the sixth area F, and the second area B, in that order in the forward rotation direction (counterclockwise direction) starting from the slit 27 of the magnetic pole portion 26 at the top of FIG. 11.

[0044] In the configuration shown in FIG. 11, the slits 27 of a pair of magnetic pole portions 26 arranged 180° apart are configured to have the same arrangement area. That is, the magnetic pole portions 26 having the slits 27 arranged in the first area A are arranged at 180° opposite positions. The magnetic pole portions 26 having the slits 27 arranged in the second area B are arranged at 180° opposite positions. The magnetic pole portions 26 having the slits 27 arranged in the third area C are arranged at 180° opposite positions. The magnetic pole portions 26 having the slits 27 arranged in the sixth area F are arranged at 180° opposite positions. This makes it possible to reduce magnetic imbalance and mass imbalance in the radial direction of the rotor 20.

[0045] The effects of this embodiment will be described. (1) Each of the multiple magnetic pole portions 26 of the rotor 20 has one slit 27 formed in the rotor core 22. The multiple slits 27 include a first slit 27a and a second slit 27b. The first slit 27a is located in the third area C or the sixth area F. The second slit 27b is located in any of the first area A, the second area B, the third area C, the fourth area D, the fifth area E, and the sixth area F.

[0046] According to this configuration, when the position of the slit 27 is changed in the circumferential direction, the phase width of the torque ripple is larger in the third area C and the sixth area F than in the other areas (see FIG. 6). Therefore, by including the first slit 27a arranged in the third area C or the sixth area F among the multiple slits 27, it is possible to improve the degree of freedom in setting the position of the second slit 27b, which generates torque ripple of an opposite phase to the first slit 27a. Furthermore, according to the above embodiment, since only one slit 27 is formed in one magnetic pole portion 26, it is possible to minimize the reduction in rotational torque caused by providing the slit 27.

[0047] (2) The second slit 27b is arranged in any one of the first area A, the second area B, the third area C, the fourth area D, the fifth area E, and the sixth area F at a position where it generates a torque ripple that is in the opposite phase to the torque ripple of the rotational (3×P) order component generated by the first slit 27a.

[0048] With this configuration, in the torque ripple of the rotational (3×P) order component, the torque ripple generated by the first slit 27a and the torque ripple generated by the second slit 27b weaken each other, thereby making it possible to prevent the torque ripple of the rotational (3×P) order component from becoming large.

[0049] (3) When viewed from the axial direction, each permanent magnet 23 has a folded shape that protrudes radially inward of the rotor 20. This configuration makes it possible to ensure a large surface area of ​​the permanent magnet 23 facing the outer core portion 25, thereby improving the magnet torque. This configuration also makes it possible to increase the volume of the outer core portion 25, thereby improving the reluctance torque. As a result, this can contribute to increasing the torque of the rotating electric machine M.

[0050] (4) The magnetic pole pitch Lp is defined as the distance between extensions of the inner surfaces of the folded-back permanent magnets 23 on the outer peripheral surface 22a of the rotor core 22. The first area A, the second area B, the third area C, the fourth area D, the fifth area E, and the sixth area F are set within the range of the magnetic pole pitch Lp. This allows the slits 27 to be provided within the range of the magnetic pole pitch Lp.

[0051] (5) The multiple slits 27 include a first slit 27a disposed in the third area C. The second slits 27b are disposed in any of the second area B, fourth area D, and sixth area F at positions where they generate torque ripples that are in opposite phase to the torque ripple of the (6×P)-th order rotational component generated by the first slits 27a. With this configuration, in the torque ripple of the (6×P)-th order rotational component, the torque ripple generated by the first slits 27a and the torque ripple generated by the second slits 27b weaken each other. This makes it possible to prevent the torque ripple of the (6×P)-th order rotational component from becoming larger.

[0052] (6) The multiple slits 27 include a first slit 27a disposed in the sixth area F. The second slits 27b are disposed in any of the first area A, the third area C, and the fifth area E at positions where they generate torque ripples that are in opposite phase to the torque ripple of the (6×P)-th order rotational component generated by the first slits 27a. With this configuration, in the torque ripple of the (6×P)-th order rotational component, the torque ripple generated by the first slits 27a and the torque ripple generated by the second slits 27b weaken each other. This makes it possible to prevent the torque ripple of the (6×P)-th order rotational component from becoming large.

[0053] (7) At least one of the areas A to F is set as an area in which no slits 27 are arranged in any of the multiple magnetic pole portions 26. This allows the torque ripples of the (3×P)-order rotational component generated in each slit 27 to interfere with each other in an appropriate manner, thereby making it possible to appropriately reduce the torque ripple of the (3×P)-order rotational component.

[0054] For example, in the above embodiment, suppose that the slits 27 are arranged in the first area A of one magnetic pole portion 26 and in the second area B of another magnetic pole portion 26. In the torque ripple of the 24th-order rotation component, the phase width of the first area A is approximately 195° to approximately 270°, and the phase width of the second area B is approximately 270° to approximately 330° (see FIG. 6 ). Therefore, in the 24th-order rotation component, a phase difference of 180° cannot be achieved between the torque ripple generated by the slits 27 arranged in the first area A and the torque ripple generated by the slits 27 arranged in the second area B. Therefore, by setting an area in which no slits 27 are arranged in any of the multiple magnetic pole portions 26 in either the first area A or the second area B, the torque ripple of the 24th-order rotation component can be suitably reduced. The same applies to the fourth area D and the fifth area E. In other words, by setting an area in which no slits 27 are arranged in any of the multiple magnetic pole portions 26 in either the fourth area D or the fifth area E, it is possible to suitably reduce the torque ripple of the 24th rotational component.

[0055] (8) By configuring the slits 27 of the pair of magnetic pole portions 26 arranged 180° apart to have the same arrangement area, magnetic imbalance and mass imbalance in the radial direction of the rotor 20 can be reduced.

[0056] (Example of change) This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0057] In the rotor 20 of the above embodiment, the core sheets that make up the rotor core 22 may be stacked while rotating. 12 and 13, the rotor core 22 is formed of a plurality of core sheets 30 stacked in the axial direction. Each core sheet 30 is made of, for example, an electromagnetic steel sheet.

[0058] Each of the multiple core sheets 30 has multiple slits 27 including first slits 27a and second slits 27b. The multiple core sheets 30 have the same configuration. That is, the arrangement of the multiple slits 27 in each core sheet 30 is the same. In the configuration shown in Figs. 12 and 13, each core sheet 30 has the slits 27 arranged in pattern 4 shown in Fig. 5, for example.

[0059] The rotor core 22 is formed by stacking core sheets 30 rotated one by one by (360° / P)°. In Fig. 12, the top core sheet 30 is the first core sheet 30a, the core sheet 30 immediately below the first core sheet 30a is the second core sheet 30b, and the core sheet 30 immediately below the second core sheet 30b is the third core sheet 30c.

[0060] In this example, the second core sheet 30b is rotated 45° clockwise relative to the first core sheet 30a. The third core sheet 30c is rotated 45° clockwise relative to the second core sheet 30b. Similarly, the fourth and subsequent core sheets 30 are rotated 45° clockwise relative to the core sheet 30 immediately above them.

[0061] In each magnetic pole portion 26 of the rotor 20 made up of multiple core sheets 30 stacked in the above manner, the positions of the slits 27 are not aligned in a straight line along the axial direction. For example, in the upper magnetic pole portion 26 in Fig. 12, the positions of the slits 27 for each core sheet 30 are, from the first row onwards, the first area A, the third area C, the fourth area D, the sixth area F, the first area A, the fourth area D, the sixth area F, the sixth area F, ...

[0062] As described above, by laminating the core sheets 30 while rotating them by (360° / P) degrees, the position of the slits 27 in each magnetic pole portion 26 can be configured to vary. This makes it possible to reduce magnetic imbalance and mass imbalance in the radial direction of the rotor 20. Furthermore, it makes it possible to reduce magnetic imbalance in the axial direction of the rotor 20. Furthermore, by laminating the core sheets 30 while rotating them by (360° / P) degrees, it becomes possible to reduce torque ripple of the S-th order rotational component in a rotating electric machine M having the number of slots S. For example, when the number of slots S is 12, it is possible to reduce torque ripple of the 12-th order rotational component.

[0063] In the above example, each core sheet 30 has the slits 27 arranged in pattern 4 shown in FIG. 5, but other than this, for example, the slits 27 may be arranged as shown in FIG. As shown in FIG. 14, the slits 27 in each core sheet 30 are configured as pattern 9 in the table of FIG. 8. When the number of magnetic poles P of the rotor 20 is 8, in pattern 9, the number of slits 27 arranged in the first area A is two. The number of slits 27 arranged in the second area B is two. The number of slits 27 arranged in the third area C is one. The number of slits 27 arranged in the fourth area D is one. The number of slits 27 arranged in the fifth area E is zero. And the number of slits 27 arranged in the sixth area F is two. The slits 27 are arranged in the first area A, the second area B, the third area C, the fourth area D, the sixth area F, and the sixth area F, in that order from the slit 27 of the magnetic pole portion 26 at the top of FIG. 14 in the forward rotation direction (counterclockwise direction).

[0064] FIG. 15 shows a rotor 20 formed by stacking the core sheets 30 shown in FIG. 14 one by one while rotating them clockwise (360° / P). The rotor 20 shown in FIG. 15 has a skewed portion 40 formed by displacing the slits 27 of each core sheet 30 circumferentially along the axial direction. In the above configuration, the arrangement areas of the slits 27 of each magnetic pole portion 26 are set to ascending or descending order in the forward rotation direction, thereby forming the skewed portion 40. In the configuration shown in FIGS. 14 and 15, for example, the slits 27 of a magnetic pole portion 26 adjacent in the forward rotation direction to a magnetic pole portion 26 having a slit 27 arranged in the first area A are arranged in one of the first area A to sixth area F. Furthermore, the slits 27 of a magnetic pole portion 26 adjacent in the forward rotation direction to a magnetic pole portion 26 having a slit 27 arranged in the second area B are arranged in one of the second area B to sixth area F. Furthermore, the slits 27 of the magnetic pole portion 26 adjacent in the forward direction to the magnetic pole portion 26 having the slits 27 arranged in the third area C are arranged in any one of the third area C to the sixth area F. Furthermore, the slits 27 of the magnetic pole portion 26 adjacent in the forward direction to the magnetic pole portion 26 having the slits 27 arranged in the fourth area D are arranged in any one of the fourth area D to the sixth area F. With this configuration, the skew portions 40 formed by the slits 27 of each core sheet 30 can more suitably reduce torque ripple. Furthermore, the skew portions 40 can reduce magnetic imbalance and mass imbalance in the radial and axial directions.

[0065] The arrangement of the slits 27 that form the skew portion 40 in the laminated state is not limited to the arrangement shown in Fig. 14. For example, the arrangement of the slits 27 of each magnetic pole portion 26 may be, in order in the forward rotation direction, the first area A, the second area B, the third area C, the sixth area F, the first area A, the second area B, the fourth area D, and the sixth area F. Even with such an arrangement, it is possible to form a skew portion by the slits 27 of each core sheet 30. Furthermore, even if the number of slits 27 in each of areas A to F is set to a number different from the configuration shown in Fig. 14, it is possible to form a skew portion by the slits 27 of each core sheet 30.

[0066] In the examples shown in FIGS. 12 to 15, the core sheets 30 are stacked with each sheet rotated by 360° / P. However, this is not limiting. For example, as shown in FIG. 16, the core sheets 30 may be stacked with every two or more sheets rotated by 360° / P. FIG. 16 shows an example of a rotor 20 in which every three core sheets 30 shown in FIG. 14 are stacked with each core sheet rotated by 360° / P. In addition, in the configuration shown in FIG. 16, the slits 27 of each core sheet 30 form a skew portion 40. This configuration also makes it possible to reduce magnetic imbalance and mass imbalance in the radial and axial directions by the skew portion 40. Furthermore, in a rotating electric machine M with a slot count of S, torque ripple of the rotational S-order component can be reduced. For example, when the slot count S is 12, torque ripple of the rotational 12-order component can be reduced.

[0067] In the above embodiment, the shape of the outer peripheral surface 22a of the rotor core 22 when viewed from the axial direction may be changed, for example, as shown in FIG. 17 . In the configuration shown in FIG. 17 , the shape of the outer peripheral surface 22a of the rotor core 22 when viewed from the axial direction is displaced radially inward from the circumferential center line Ls of the magnetic pole portion 26 toward the magnetic pole boundary lines Ld on both sides of the circumferential center line Ls. In other words, the outer diameter of the rotor core 22, i.e., the distance from the axis L1 to the outer peripheral surface 22a of the rotor core 22, is not uniform in the circumferential direction. Specifically, the outer diameter of the rotor core 22 is maximum at the circumferential center line Ls of each magnetic pole portion 26 and minimum at each magnetic pole boundary line Ld. In FIG. 17 , a reference circle Ca is shown, which has the same diameter as the maximum diameter of the rotor core 22. Note that the radially outer surface of each magnetic pole portion 26 has an arc shape with a diameter smaller than the diameter of the reference circle Ca when viewed from the axial direction.

[0068] 17, the radially outer surface of the magnetic pole portion 26 is shaped to be displaced radially inward from the circumferential center line Ls toward the magnetic pole boundary lines Ld on both sides of the circumferential center line Ls, which smooths the transition of the magnetic poles, thereby making it possible to further reduce torque ripple.

[0069] The slits 27 in the above embodiment are groove-shaped with an open radially outer end, but may also be slit-shaped with a closed radially outer end, for example. The arrangement of the slits 27 in each magnetic pole portion 26 is not limited to the 22 patterns 1 to 22 shown in the above embodiment. The slits 27 in each magnetic pole portion 26 may be arranged in a configuration other than patterns 1 to 22 as long as they have a first slit 27a arranged in the third area C or the sixth area F and a second slit 27b that generates a torque ripple that is in the opposite phase to the torque ripple of the rotational (3×P)-order component generated by the first slit 27a.

[0070] The settings of the first area A to the sixth area F are not limited to those in the above embodiment. For example, the magnetic pole portion 26 may be divided into 12 equal areas in the circumferential direction, and the fourth to ninth ranges when counted in the reverse direction from the second end 26b side may be designated as the first area A, the second area B, the third area C, the fourth area D, the fifth area E, and the sixth area F, respectively.

[0071] The number of magnetic poles P of the rotor 20 is not limited to eight as in the above embodiment, but may be set to seven or less, or nine or more. The permanent magnets 23 are not limited to a V-shape, but may be U-shaped or other folded shapes that protrude radially inward of the rotor 20. They may also be I-shaped or other shapes other than folded shapes.

[0072] Although the permanent magnets 23 are formed by injection molding a magnetic material into the magnet accommodating holes 24 of the rotor core 22, the permanent magnets 23 may be manufactured in advance and then inserted and fixed into the magnet accommodating holes 24 of the rotor core 22.

[0073] In addition to the above, the configuration of the rotor 20 and the configuration of the rotating electrical machine M may be changed as appropriate. The embodiments and modifications disclosed herein are illustrative in all respects, and the present invention is not limited to these examples. That is, the scope of the present invention is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims.

[0074] (Addendum) The features of the present invention are as follows. [1] A rotating electric machine (M) comprising: a rotor (20) having a rotor core (22) and permanent magnets (23) embedded in the rotor core; and a stator (10) that applies a rotating magnetic field to the rotor, wherein the rotor has a plurality of magnetic pole portions (26) formed at equal angular intervals in the circumferential direction, each of the plurality of magnetic pole portions having one slit (27) formed in the rotor core, and the number of the magnetic pole portions is P, and the angle from one circumferential end (26a) to the other circumferential end (26b) of each magnetic pole portion is 360° / P, and the angle from the one circumferential end (26a) of each magnetic pole portion to the other circumferential end (26b) of each magnetic pole portion is 360° / P. a rotating electric machine in which, when the circumferential direction is divided equally into 12 areas to the other end in the circumferential direction, the 4th to 9th areas counted in order from the one circumferential end side are respectively a first area (A), a second area (B), a third area (C), a fourth area (D), a fifth area (E), and a sixth area (F), and the plurality of slits include a first slit (27a) and a second slit (27b), the first slit is arranged in the third area or the sixth area, and the second slit is arranged in any of the first area, the second area, the third area, the fourth area, the fifth area, and the sixth area.

[0075] [2] The rotating electric machine described in [1], wherein the second slit is arranged in any one of the first area, the second area, the third area, the fourth area, the fifth area and the sixth area at a position where it generates a torque ripple of an opposite phase to the torque ripple of the rotational (3×P)th order component generated by the first slit.

[0076] [3] The rotating electric machine according to [1] or [2], wherein each of the permanent magnets has a folded shape that protrudes radially inward of the rotor. [4] A rotating electric machine as described in [3], wherein the magnetic pole pitch (Lp) is the distance between the extension lines of the inner surfaces of the folded-back permanent magnets on the outer peripheral surface of the rotor core, and the first area, the second area, the third area, the fourth area, the fifth area, and the sixth area are set within the range of the magnetic pole pitch.

[0077] [5] A rotating electric machine according to any one of [1] to [4], wherein the first slit is arranged in the third area, and the second slit is arranged in any one of the second area, the fourth area, and the sixth area at a position that generates a torque ripple that is in the opposite phase to the torque ripple of the rotational (6×P)th order component generated by the first slit.

[0078] [6] A rotating electric machine according to any one of [1] to [5], wherein the first slit is arranged in the sixth area, and the second slit is arranged in any one of the first area, the third area, and the fifth area at a position that generates a torque ripple that is in the opposite phase to the torque ripple of the rotational (6×P)th order component generated by the first slit.

[0079] [7] A rotating electric machine according to any one of [1] to [6], wherein an area in which the slits are not arranged in any of the plurality of magnetic pole portions is set in at least one of the first area, the second area, the third area, the fourth area, the fifth area and the sixth area.

[0080] [8] A rotating electric machine according to any one of [1] to [7], wherein the slits of the pair of magnetic pole portions arranged 180° apart have the same arrangement area. [9] A rotating electric machine described in any one of [1] to [8], wherein the rotor core is formed of a plurality of core sheets (30) stacked in the axial direction, the plurality of core sheets having the same configuration, each of the plurality of core sheets having the plurality of slits including the first slit and the second slit, and the rotor core is formed by stacking the core sheets in a state where each predetermined number of sheets are rotated by (360° / P)°.

[0081]

[10] The rotating electric machine according to [9], wherein the rotor core is formed by laminating the core sheets in a state where each sheet is rotated by (360° / P)°.

[11] A rotating electric machine as described in [9] or

[10] , wherein the plurality of slits in the core sheets are arranged so that when the core sheets are stacked together, the slits in each core sheet form a skew portion (40) in which the slits are displaced circumferentially in the axial direction. [Explanation of symbols]

[0082] M rotating electric machine, 10 stator, 20 rotor, 22 rotor core, 22a outer peripheral surface, 23 permanent magnet, 26 magnetic pole portion, 26a first end (one circumferential end), 26b second end (other circumferential end), 27 slit, 27a first slit, 27b second slit, 30 (30a, 30b, 30c) core sheet, 40 skew portion, A first area, B second area, C third area, D fourth area, E fifth area, F sixth area, Lp magnetic pole pitch.

Claims

1. a rotor (20) having a rotor core (22) and permanent magnets (23) embedded in the rotor core; a stator (10) disposed radially outside the rotor and applying a rotating magnetic field to the rotor; a rotor having a plurality of magnetic pole portions (26) formed at equal angular intervals in a circumferential direction, the magnetic pole portions (26) including the permanent magnets and a portion of the rotor core; Each of the plurality of magnetic pole portions has only one slit (27) formed on an outer surface of an outer core portion, which is a portion of the rotor core located radially outward from the permanent magnet, The angle from one circumferential end (26a) to the other circumferential end (26b) of each magnetic pole portion is 360° / P, where P is the number of the magnetic pole portions; When the magnetic pole portion is equally divided into 12 areas from one circumferential end to the other circumferential end, the 4th to 9th areas counted from the one circumferential end side of the 12 areas are designated as a first area (A), a second area (B), a third area (C), a fourth area (D), a fifth area (E), and a sixth area (F), respectively; The plurality of slits include first slits (27a) and second slits (27b), the first slit is disposed in at least one of the third area and the sixth area, the second slit is located at a position where it generates a torque ripple that is in opposite phase to the torque ripple of the rotational (3×P) order component generated by the first slit, and is disposed in at least one of the first area, the second area, the third area, the fourth area, the fifth area, and the sixth area. Rotating electric motor.

2. Each of the permanent magnets has a folded shape that protrudes toward the inside in the radial direction of the rotor. The rotating electric machine according to claim 1 .

3. The distance between extension lines of the inner surfaces of the folded permanent magnets on the outer peripheral surface of the rotor core is defined as a magnetic pole pitch (Lp), the first area, the second area, the third area, the fourth area, the fifth area, and the sixth area are set within the range of the magnetic pole pitch, The rotating electric machine according to claim 2 .

4. the first slit is disposed in the third area, the second slit is disposed in any one of the second area, the fourth area, and the sixth area at a position where it generates a torque ripple that is in an opposite phase to a torque ripple of a rotational (6×P)-order component generated by the first slit. The rotating electric machine according to claim 1 .

5. the first slit is disposed in the sixth area, the second slit is disposed in any one of the first area, the third area, and the fifth area at a position where it generates a torque ripple that is in an opposite phase to a torque ripple of a rotational (6×P)-order component generated by the first slit. The rotating electric machine according to claim 1 .

6. an area in which the slits are not arranged in any of the plurality of magnetic pole portions is set in at least one of the first area, the second area, the third area, the fourth area, the fifth area, and the sixth area; The rotating electric machine according to claim 1 .

7. The arrangement areas of the slits in the pair of magnetic pole portions arranged 180° opposite to each other are the same. The rotating electric machine according to claim 1 .

8. The rotor core is formed of a plurality of core sheets (30) stacked in the axial direction, The plurality of core sheets have the same configuration, Each of the plurality of core sheets is provided with the plurality of slits including the first slit and the second slit, The rotor core is formed by laminating the core sheets in a state where each predetermined number of core sheets is rotated by (360° / P)°. The rotating electric machine according to claim 1 .

9. The rotor core is formed by laminating the core sheets in a state where each sheet is rotated by (360° / P)°. The rotating electric machine according to claim 8.

10. The plurality of slits in the core sheets are arranged so as to form a skew portion (40) in which the slits of each core sheet are displaced in the circumferential direction in the axial direction when the core sheets are stacked together. The rotating electric machine according to claim 8 or 9.

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