Rotor and rotating electric machine

Abstract

To provide the rotor of a rotating electrical machine with which it is possible to reduce a leakage magnetic flux while taking it into account to secure the strength of a centrifugal force.SOLUTION: An outside core unit 25, which is enclosed by a magnet housing hole 24 and a permanent magnet 23, is supported to the circumferential region of a rotor core 22 by a 3-point support form consisting of outer circumferential bridge units 22d, 22e and a reinforcement bridge unit 22c. In each individual core sheet 30, an outside core part 34a, which is supported by an outer circumferential bridge piece 31c and a reinforcement bridge piece 31d, and an outside core part 34b, which is supported by only an outer circumferential bridge piece 32c, are made to coexist in constituting one outside core unit 25. When a plurality of core sheets 30 are laminated to create a rotor core 22, a multi-point support form for the outside core unit 25 by the outer circumferential bridge units 22d, 22e and the reinforcement bridge unit 22c is established.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an embedded magnet rotor and a rotating electric machine. [Background technology]

[0002] In rotating electrical machines, an interior permanent magnet (IPM) rotor is well known, in which permanent magnets are embedded in the rotor core at a radially inner position. The interior permanent magnet rotor is configured to obtain reluctance torque from the outer core portion located radially outward of the permanent magnets in addition to the magnet torque from the permanent magnets.

[0003] In an embedded magnet rotor, as shown in Patent Document 1, for example, the permanent magnets are embedded in a folded shape that is convex radially inward, such as a V or U shape, when viewed in the axial direction. By making the folded shape of the permanent magnet deeper radially inward, it is possible to configure a larger outer core portion. In other words, the larger the outer core portion, the more reluctance torque can be obtained, which can lead to higher torque in a rotating electric machine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-85779 Summary of the Invention [Problem to be solved by the invention]

[0005] The embedded magnet rotor requires the formation of magnet accommodating holes in the rotor core to accommodate the permanent magnets. The outer core portion, which is surrounded by the magnet accommodating holes, is connected to the main body of the rotor core by narrow connecting portions called bridge portions. The bridge portions are also the portions where some of the effective magnetic flux leaks. To reduce leakage flux and thereby increase the torque of a rotating electric machine, it is desirable to minimize the bridge portions or eliminate some of them.

[0006] However, since the bridge portions also support the outer core portion relative to the surrounding area of the rotor core, minimizing or eliminating the bridge portions appropriately can lead to a decrease in the support rigidity of the outer core portion, increasing concerns about a decrease in the centrifugal strength of the rotor, for example.

[0007] An object of the present invention is to provide a rotor and a rotating electrical machine that can reduce leakage magnetic flux while ensuring centrifugal force strength. [Means for solving the problem]

[0008] The rotor that solves the above problem is an embedded magnet rotor (20) that includes a rotor core (22) that is formed by laminating a plurality of core sheets (30) and has magnet accommodating holes (24) that are folded back to convexly inward in the radial direction, and permanent magnets (23) that are provided in the magnet accommodating holes of the rotor core, and that includes the permanent magnets located radially inside the rotor core and outer core portions (25) that are part of the rotor core located radially outside the permanent magnets, and that has a plurality of magnetic pole portions (26). The outer core portion of the rotor core is formed by laminating the outer core portions (34a, 34b) of the individual core sheets. and is supported at the peripheral portion of the rotor core by bridge portions (22d, 22e, 22c) at a plurality of locations, including a bridge portion located on at least one side of a pair of radially outer end portions (24c) of the folded-back magnet accommodating hole, and at least the outer core portion (34b) supported by one bridge piece (32c) of the core sheet constituting the bridge portion (22e) at the radially outer end portion on one side is mixed, and by stacking a plurality of the core sheets, a support mode of the outer core portion by the bridge portions at a plurality of locations is established.

[0009] The rotating electric machine that solves the above problem is a rotating electric machine (M) that includes: a rotor core (22) that is formed by laminating a plurality of core sheets (30) and has magnet accommodating holes (24) that are folded back in a convex shape on the radially inward side; permanent magnets (23) that are provided in the magnet accommodating holes of the rotor core, the permanent magnets being positioned radially inside the rotor core; and an outer core portion (25) that is a part of the rotor core being positioned radially outside the permanent magnets; an embedded magnet type rotor (20) that is configured with a plurality of magnetic pole portions (26); and a stator (10) that applies a rotating magnetic field to the rotor, wherein the outer core portion of the rotor core is formed by laminating a plurality of core sheets (30) in a convex shape on the radially inward side. The rotor core is constructed by stacking core portions (34a, 34b) and is supported on the surrounding area of the rotor core by bridge portions (22d, 22e, 22c) at multiple locations, including a bridge portion located on at least one side of a pair of radially outer end portions (24c) of the folded-back magnet accommodating hole, and is configured so that at least the outer core portion (34b) supported by one bridge piece (32c) of the core sheet constituting the bridge portion (22e) at the radially outer end portion on one side is mixed, and by stacking multiple core sheets, a support pattern of the outer core portion by the bridge portions at multiple locations is established.

[0010] According to the rotor and rotating electric machine described above, the outer core portion surrounded by the magnet accommodating hole and the permanent magnet is supported by multiple bridge portions, including bridge portions located on at least one side of a pair of radially outer ends of the folded magnet accommodating hole, relative to the periphery of the rotor core. In each core sheet, when forming one outer core portion, at least one outer core portion supported by one bridge piece constituting the bridge portion at one radially outer end is mixed. When multiple core sheets are stacked to form a rotor core, the outer core portion is supported by multiple bridge portions. The support rigidity of the outer core portion supported by multiple bridge portions is sufficiently high, ensuring the centrifugal force strength of the rotor. Furthermore, by mixing the outer core portions supported by one bridge piece, the individual bridge pieces constituting the bridge portions supporting the outer core portion are appropriately thinned out, thereby reducing leakage magnetic flux, which is a concern at each bridge portion. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating the configuration of a rotating electric machine having an embedded magnet rotor according to an embodiment. [Figure 2] FIG. 2 is a plan view of the rotor in the embodiment. [Figure 3] 4A and 4B are plan views of a core sheet used in the embodiment. [Figure 4] 4 is a cross-sectional view of the rotor shown in FIG. 2 along line 4-4. [Figure 5] 5 is a cross-sectional view of the rotor shown in FIG. 2 along line 5-5. [Figure 6] 6 is a cross-sectional view of the rotor shown in FIG. 2 along line 6-6. [Figure 7] FIG. 2 is a configuration diagram of a rotating electric machine including a rotor according to the embodiment. [Figure 8] FIG. 2 is a configuration diagram of a rotating electric machine including a rotor in Comparative Example 1. [Figure 9] FIG. 10 is a configuration diagram of a rotating electric machine including a rotor in Comparative Example 2. [Figure 10] A comparison diagram of the torque (cogging torque) corresponding to various shapes of permanent magnets. [Figure 11] A comparison diagram of torque (torque ripple) corresponding to various permanent magnet shapes. [Figure 12] FIG. 10 is a comparison diagram of torque ripple rates corresponding to various shapes of tapered portions. [Figure 13] FIG. 10 is a comparison diagram of torque ripple rates corresponding to various shapes of tapered portions. [Figure 14] FIG. 10 is a diagram illustrating a configuration of a rotating electric machine according to a modified example in which the permanent magnet shapes of adjacent magnetic pole portions are different. [Figure 15] FIG. 10 is a comparison diagram of cogging torque in modified examples. [Figure 16] FIG. 10 is a comparison diagram of torque ripple rates in modified examples. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of a rotor and a rotating electrical machine will be described below. [Rotating Electric Machine M] The rotating electric machine M of this embodiment shown in Fig. 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 the radially inner space of the stator 10. The stator 10 applies a rotating magnetic field to the rotor 20. The rotor 20 rotates in response to the rotating magnetic field generated by the stator 10.

[0013] [Stator 10] The stator 10 includes a substantially annular stator core 11. The stator core 11 is made of a magnetic metal material, e.g., a laminate of multiple electromagnetic steel sheets. The stator core 11 has twelve teeth 12, which extend radially inward and are equally spaced circumferentially in this embodiment. Each tooth 12 has the same shape. The radially inner ends of the teeth 12 are substantially T-shaped, and the tip surfaces 12a are arc-shaped, conforming to the outer circumferential surface of the rotor 20. Each of the twelve teeth 12 is wound with a winding 13 in a concentrated winding manner. In other words, the stator 10 has twelve magnetic poles. The windings 13 are connected in three phases and function as U, V, and W phases, respectively, as shown in FIG. 1 . When power is supplied to the windings 13, a rotating magnetic field is generated in the stator 10 to rotate the rotor 20. In such a stator 10, the outer peripheral surface of the stator core 11 is fixed to the inner peripheral surface of the housing 14.

[0014] [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 embedded in radially inner positions of the rotor core 22. In other words, the rotor 20 has eight magnetic poles. The rotor 20 is rotatably disposed relative to the stator 10 with the rotating shaft 21 supported by bearings (not shown) provided in the housing 14.

[0015] [Rotor core 22] As shown in Fig. 2, the rotor core 22 has magnet accommodating holes 24 for accommodating 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 penetrates the rotor core 22 in the axial direction. When viewed in the axial direction, each magnet accommodating hole 24 has a generally V-shaped folded shape that protrudes radially inward.

[0016] Each magnet accommodating hole 24 has a pair of linear portions 24a that are linear when viewed in the axial direction and a bent portion 24b connecting the radially inner ends of the pair of linear portions 24a. The pair of linear portions 24a gradually approach each other from the radially outer side to the radially inner side. Furthermore, adjacent linear portions 24a of adjacent magnet accommodating holes 24 are arranged side by side so as to be parallel to each other. The radially outer end 24c of each linear portion 24a is located near the outer peripheral surface 22a of the rotor core 22, and a portion thereof opens to the outer peripheral surface 22a (see FIG. 4). The bent portion 24b is located near the shaft insertion hole 22b at the center of the rotor core 22, into which the rotating shaft 21 is inserted. In other words, each magnet accommodating hole 24 has a substantially V-shaped folded shape that protrudes greatly from the radially outer side to the radially inner side.

[0017] Specifically, the magnet accommodating holes 24 of this embodiment are a mixture of two types of hole structures: the magnet accommodating holes 24 of the first mode A1 and the magnet accommodating holes 24 of the second mode A2. The magnet accommodating holes 24 of the first and second modes A1 and A2 are alternately arranged in the circumferential direction, with each being arranged every other one in the circumferential direction. The magnet accommodating holes 24 of the first and second modes A1 and A2 are configured by first and second magnet through holes 31 and 32 formed in a core sheet 30 (see FIG. 3 ) described below, alternately arranged in the axial direction. The magnet accommodating holes 24 of the first and second modes A1 and A2 appear to be different holes when viewed in the axial direction because the axial arrangement of the first and second magnet through holes 31 and 32 is different, but they are substantially configured similarly. The detailed configuration of the magnet accommodating holes 24 of the first and second modes A1 and A2 will be described later.

[0018] [Permanent magnet 23 and outer core portion 25] In this embodiment, the permanent magnets 23 are bonded magnets formed by molding and solidifying a magnetic material made by mixing magnetic powder with resin. That is, the permanent magnets 23 are formed by using the magnet accommodating holes 24 of the rotor core 22 as a molding die, filling the magnet accommodating holes 24 with unsolidified magnetic material by injection molding without gaps, and then solidifying the material inside the magnet accommodating holes 24 after filling. Therefore, the shape of the magnet accommodating holes 24 becomes the outer shape of the permanent magnets 23. The magnetic powder used for the permanent magnets 23 in this embodiment is, for example, a samarium iron nitrogen (SmFeN) magnet, but other rare earth magnets, etc. may also be used.

[0019] As shown in FIG. 2, each permanent magnet 23 is formed directly in each magnet accommodating hole 24, and therefore has a generally V-shaped folded shape convex radially inward when viewed in the axial direction, which corresponds to the shape of each magnet accommodating hole 24. Each permanent magnet 23 has a pair of straight portions 23a located within the pair of straight portions 24a of each magnet accommodating hole 24, and a bent portion 23b located within the bent portion 24b of each magnet accommodating hole 24 and connecting the radially inner ends of the pair of straight portions 23a. The pair of straight portions 23a gradually approach each other from the radially outer side to the radially inner side. Furthermore, adjacent straight portions 23a of adjacent permanent magnets 23 are arranged side by side so as to be parallel to each other. The radially outer ends of the straight portions 23a are located near the outer peripheral surface 22a of the rotor core 22, and are partially exposed to the outer peripheral surface 22a (see FIG. 4). The bent portion 23b is located near the shaft insertion hole 22b at the center of the rotor core 22, into which the rotating shaft 21 is inserted. In other words, each permanent magnet 23 has a substantially V-shaped folded shape that is largely convex from the outer side toward the inner side in the radial direction.

[0020] The portion of the rotor core 22 located inside the V-shaped folded shape of the permanent magnet 23 and radially outward of the permanent magnet 23 functions as an outer core portion 25 that faces the stator 10 and generates reluctance torque. The number of outer core portions 25 is the same as that of the permanent magnets 23, and eight outer core portions 25 are provided. Each outer core portion 25 has a substantially triangular shape with one vertex facing toward the center of the rotor 20 when viewed in the axial direction. One permanent magnet 23 and one outer core portion 25 constitute one magnetic pole portion 26 of the rotor 20. The rotor 20 of this embodiment has eight magnetic pole portions 26. The curvature of the outer peripheral surface 26a of each magnetic pole portion 26 of this embodiment is set to be larger than the curvature when the outer peripheral surface 22a of the rotor core 22 is a uniform circumference. In other words, the outer peripheral surface 22a of the rotor core 22 has a wavy shape that is slightly convex radially outward for each magnetic pole portion 26.

[0021] As described above, the magnet accommodating holes 24 in which the permanent magnets 23 are provided are of two types, the first and second modes A1 and A2, but have substantially the same hole structure. Therefore, although the magnetic pole portions 26, i.e., the permanent magnets 23 and the outer core portions 25, appear to have different shapes and arrangements when viewed in the axial direction, they are substantially similar in configuration. Hereinafter, the first and second modes A1 and A2 will be used for the permanent magnets 23 and outer core portions 25 corresponding to the magnet accommodating holes 24, as well as for the magnetic pole portions 26. There are eight magnetic pole boundary lines Ld between adjacent magnetic pole portions 26, spaced equally apart in the circumferential direction. The magnetic pole opening angle θm between adjacent magnetic pole boundary lines Ld is 45°. The circumferential center lines of adjacent magnetic pole boundary lines Ld are the magnetic pole center line Ls of each magnetic pole portion 26. Therefore, the magnetic pole portions 26, which have substantially the same configuration, are substantially symmetrical about the magnetic pole center line Ls.

[0022] Each outer core portion 25 has three vertices that are connected to the surrounding area of the rotor core 22 by connecting portions called bridge portions. The radially inner vertex portions of each outer core portion 25 are supported by reinforcing bridge portions 22c. The reinforcing bridge portions 22c are bridge portions that traverse the bent portions 24b of the magnet accommodating holes 24 in the hole width direction, in this case, traverse the radial direction of the rotor core 22. The two radially outer vertices of each outer core portion 25 are supported by outer peripheral bridge portions 22d, 22e, respectively. The outer peripheral bridge portions 22d, 22e are bridge portions that extend in the circumferential direction of the rotor core 22 from the radially outer end portions 24c of the straight portions 24a of the magnet accommodating holes 24.

[0023] Furthermore, inter-pole bridge portions 22f are provided between adjacent magnet accommodating holes 24. The inter-pole bridge portions 22f are bridge portions that extend radially between the linear portions 24a of adjacent magnet accommodating holes 24. The inter-pole bridge portions 22f, the reinforcing bridge portions 22c, and the outer periphery bridge portions 22d, 22e correspond to the magnet accommodating holes 24 of the first and second modes A1, A2, and are configured so that their presence or absence alternates for each of the axially laminated core sheets 30 (see FIGS. 4 to 6). The order of presence or absence of the inter-pole bridge portions 22f, the reinforcing bridge portions 22c, and the outer periphery bridge portions 22d, 22e is reversed for each of the magnet accommodating holes 24 of the first and second modes A1, A2. A detailed configuration will be described later.

[0024] The permanent magnets 23 embedded 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) after the pre-magnetization magnetic material has solidified. In this case, each permanent magnet 23 is magnetized in its thickness direction. The straight portions 24a are magnetized in a direction perpendicular to the radial direction of the magnet, and the curved portions 24b are magnetized in the radial direction. The permanent magnets 23 of each magnetic pole portion 26 are magnetized so that their polarities alternate in the circumferential direction. In this way, each magnetic pole portion 26 is configured to generate both a magnet torque from the permanent magnet 23 and a reluctance torque from the outer core portion 25.

[0025] [Core Sheet 30] The rotor core 22 is constructed by laminating multiple core sheets 30 made of electromagnetic steel sheets in the axial direction L. Each core sheet 30 has the same configuration as shown in FIG. 3(a). Since each core sheet 30 uses the same parts, management is easy. Note that the core sheet 30 shown in FIG. 3(b) appears to have a different shape at first glance from the core sheet 30 shown in FIG. 3(a), but in fact it is positioned at a second position rotated 45°, which is one magnetic pole, from the first position shown in FIG. 3(a).

[0026] A single core sheet 30 is formed with a mixture of two different types of magnet through holes, namely, first magnet through holes 31 and second magnet through holes 32. The first and second magnet through holes 31, 32 are alternately arranged in the circumferential direction in each core sheet 30, with each through hole being arranged every other circumferentially. The first and second magnet through holes 31, 32 each have a generally V-shaped folded shape that protrudes radially inward. That is, the first magnet through hole 31 has a shape in which the radially inner ends of a pair of straight portions 31a are connected by a bent portion 31b. The second magnet through hole 32 has a shape in which the radially inner ends of a pair of straight portions 32a are connected by a bent portion 32b.

[0027] The first magnet through hole 31 has its hole center line L1 offset in the counterclockwise direction in FIG. 3(a) from the magnetic pole center line Ls of each magnetic pole portion 26. In contrast, the second magnet through hole 32 has its hole center line L2 offset in the clockwise direction in FIG. 3(a) from the magnetic pole center line Ls of each magnetic pole portion 26. As a result, the linear portions 31a, 32a of the first magnet through hole 31 and the second magnet through hole 32 on its clockwise side are spaced apart, resulting in the presence of individual inter-pole bridge pieces 33 that make up the inter-pole bridge portion 22f. On the other hand, the linear portions 31a, 32a of the first magnet through hole 31 and the second magnet through hole 32 on its counterclockwise side are connected to each other, resulting in the absence of individual inter-pole bridge pieces 33 that make up the inter-pole bridge portion 22f. In this embodiment, the linear portions 31a and 32a are joined exactly at the magnetic pole boundary line Ld, and the width of the linear portions 31a and 32a themselves does not decrease.

[0028] Furthermore, the side where the linear portions 31a, 32a of the first and second magnet through holes 31, 32 are spaced apart, i.e., the side where the inter-pole bridge pieces 33 are present, is configured to have the individual peripheral bridge pieces 31c, 32c that make up the peripheral bridge portions 22d, 22e. The inter-pole bridge pieces 33 and the peripheral bridge pieces 31c, 32c are connected to each other in a rational relationship that supports each other. On the other hand, the side where the linear portions 31a, 32a of the first and second magnet through holes 31, 32 are joined is configured to have the individual peripheral bridge pieces 31c, 32c that make up the peripheral bridge portions 22d, 22e absent. Furthermore, the bent portion 31b of the first magnet through hole 31 is configured to have the individual reinforcing bridge pieces 31d that make up the reinforcing bridge portion 22c. On the other hand, the bent portion 32b of the second magnet through hole 32 is configured to have the individual reinforcing bridge pieces 31d that make up the reinforcing bridge portion 22c absent.

[0029] In other words, each outer core portion 34a, which is surrounded by the first magnet through holes 31 to form the outer core portion 25, is supported at two locations: the reinforcing bridge piece 31d and the outer periphery bridge piece 31c on the side where the inter-pole bridge piece 33 is located. On the other hand, each outer core portion 34b, which is surrounded by the second magnet through holes 32 to form the outer core portion 25, is supported at only one location: the outer periphery bridge piece 32c on the side where the inter-pole bridge piece 33 is located. In each core sheet 30, the support rigidity of each outer core portion 34a, 34b is not very high. However, the rotor core 22 of this embodiment is formed by stacking (so-called rotating) core sheets 30 arranged in the first position shown in FIG. 3(a) and arranged in the second position shown in FIG. 3(b), which is rotated 45 degrees. The outer core portion 25 of the rotor core 22, which is produced by rolling the core sheets 30, is supported at a total of three points: the reinforcing bridge portion 22c and two outer peripheral bridge portions 22d and 22e, thereby increasing the support rigidity of the outer core portion 25.

[0030] In addition, in the first magnet through hole 31, a tapered portion 31e is provided at an inner corner of the V-shaped turn-back at the radially outer end of the straight portion 31a located counterclockwise from the magnetic pole center line Ls. In the first magnet through hole 31, a tapered portion 31f is also provided at an inner corner of the V-shaped turn-back at the radially outer end of the straight portion 31a located clockwise from the magnetic pole center line Ls. In the second magnet through hole 32, a tapered portion 32d is also provided at an inner corner of the V-shaped turn-back at the radially outer end of the straight portion 32a located counterclockwise from the magnetic pole center line Ls. In the second magnet through hole 32, a tapered portion 32e is also provided at an inner corner of the V-shaped turn-back at the radially outer end of the straight portion 32a located clockwise from the magnetic pole center line Ls. The tapered portions 31e, 31f, 32d, and 32e each have an inner edge that protrudes obliquely inward, and the tapered portions 31e and 32e are set to protrude by a larger amount than the tapered portions 31f and 32d.

[0031] [Fabrication of rotor core 22 and rotor 20 by laminating core sheets 30] In this embodiment, when manufacturing the rotor 20 including the rotor core 22, the core sheets 30 are stacked one by one in the axial direction so that those arranged in the first position shown in Fig. 3(a) and those arranged in the second position rotated 45° as shown in Fig. 3(b) alternate. As a result, the first magnet through holes 31 and the second magnet through holes 32 alternately overlap in the axial direction, and each magnet accommodating hole 24 of the rotor core 22 is formed by the first and second magnet through holes 31, 32 that overlap in the axial direction.

[0032] In the axial view shown in FIG. 2 , the magnet accommodating holes 24 of the first embodiment A1 are the magnet accommodating holes 24 and the magnetic pole portions 26 of the first embodiment A1 where the first magnet through holes 31 appear on the axial end surface of the rotor core 22. In the magnet accommodating holes 24 of the first embodiment A1, the first magnet through holes 31 are in the first core sheet 30, and the second magnet through holes 32 are in the second core sheet 30. In other words, the odd-numbered core sheets 30 are configured with the first magnet through holes 31, and the even-numbered core sheets 30 are configured with the second magnet through holes 32. Similarly, in the axial view, the magnet accommodating holes 24 of the second embodiment A2 are the magnet accommodating holes 24 and the magnetic pole portions 26 of the second embodiment A2 where the second magnet through holes 32 appear on the axial end surface of the rotor core 22. In the magnet accommodating holes 24 of the second embodiment A2, the first magnet through holes 32 are in the first core sheet 30, and the first magnet through holes 31 are in the second core sheet 30. That is, odd-numbered core sheets 30 are configured with through holes 32 for second magnets, and even-numbered core sheets 30 are configured with through holes 31 for first magnets.

[0033] In this case, the first magnet through hole 31 is offset counterclockwise from the magnetic pole center line Ls of each magnetic pole portion 26, and the second magnet through hole 32 is offset clockwise from the magnetic pole center line Ls. That is, each magnet accommodating hole 24 in the first and second modes A1 and A2 is zigzag in the axial direction, and the inner surface of each magnet accommodating hole 24 is configured with an uneven shape. Therefore, each permanent magnet 23 produced by injection molding into each magnet accommodating hole 24 has a portion thereof entering the uneven portion on the inner surface of each magnet accommodating hole 24, and the magnets are firmly bonded to each other.

[0034] If an even number of core sheets 30 are stacked, each magnet accommodating hole 24 will be formed by the same number of first and second magnet through holes 31, 32 in either the first or second mode A1, A2. Therefore, even if the hole shapes of each magnet accommodating hole 24 that appear on the axial end surface of the rotor core 22 are different in the first and second modes A1, A2, the magnetic pole portions 26 of the first and second modes A1, A2 will have substantially the same configuration. The rotor core 22 of this embodiment is formed by, for example, an even number of core sheets 30.

[0035] As an example of fixing multiple core sheets 30, adjacent core sheets 30 in the stacking direction are fixed together using an adhesive (not shown). As another example, adjacent core sheets 30 may be fixed together using crimping portions 35 (see FIG. 2). The crimping portions 35 are formed, for example, by making the front side of the core sheet 30 concave and the back side convex, and crimping the concave and convex portions in the stacking direction. One preferred example of the locations of the crimping portions 35 is to set one each near the center of each outer core portion 25 on the magnetic pole center line Ls of each magnetic pole portion 26. The arrangement and number of the crimping portions 35 are not limited to this and may be changed as appropriate.

[0036] [Operation of this embodiment] The operation of this embodiment will be described. In the rotor 20 shown in FIG. 2, the outer core portion 25 in each magnetic pole portion 26 is supported at three locations: one reinforcing bridge portion 22c and two outer periphery bridge portions 22d, 22e. In contrast, in each core sheet 30 shown in FIG. 3(a), each outer core portion 34a surrounded by the first magnet through hole 31 is supported at two locations: the reinforcing bridge piece 31d and the outer periphery bridge piece 31c. Furthermore, each outer core portion 34b surrounded by the second magnet through hole 32 is supported at only one location: the outer periphery bridge piece 32c. By fabricating the rotor core 22 by stacking multiple core sheets 30, the outer core portion 25 is supported at three locations: the reinforcing bridge portion 22c and the two outer periphery bridge portions 22d, 22e. The outer core portion 25 has high support rigidity in the completed rotor core 22, and the rotor core 22, i.e., the rotor 20, has sufficient centrifugal strength. In addition, the reinforcement bridge portion 22c and the outer periphery bridge portions 22d, 22e shown in Figures 4 and 5 have individual reinforcement bridge pieces 31d and outer periphery bridge pieces 31c, 32c for each axial core sheet 30. In other words, the reinforcement bridge portion 22c and the outer periphery bridge portions 22d, 22e are appropriately thinned out in the axial direction. This also reduces leakage magnetic flux, which is a concern in the reinforcement bridge portion 22c and the outer periphery bridge portions 22d, 22e. In other words, the rotor 20 of this embodiment is configured to ensure both centrifugal force strength and reduction of leakage magnetic flux.

[0037] As shown in Fig. 2, each magnet accommodation hole 24 is configured such that the through holes 31 and 32 for the first and second magnets are axially mixed in consideration of the stacking of the rotor core 22. That is, each magnet accommodation hole 24 has a zigzag shape in the axial direction and its inner surface is uneven, and each permanent magnet 23 enters the uneven portions of the inner surface of each magnet accommodation hole 24 at the molding stage. Therefore, the coupling between each permanent magnet 23 and the rotor core 22 becomes strong, contributing to enhancing the rigidity of the entire rotor 20. Also, regarding the tapered portions 31e, 31f, 32d, and 32e of the through holes 31 and 32 for the first and second magnets, the amounts of protrusion are made different, so that the tapered portions 23c at the inner corner portions of the V-shaped folded-back shapes of the corresponding permanent magnets 23 also have an uneven shape in the axial direction. Also in this portion, the coupling between each permanent magnet 23 and the rotor core 22 becomes strong. Further, since the reinforcing bridge portions 22c, the outer peripheral bridge portions 22d and 22e, and the inter-pole bridge portions 22f shown in Figs. 4 to 6 are configured to be appropriately thinned out in the axial direction, each permanent magnet 23 also enters the thinned-out portions. Therefore, also in this portion, the coupling between each permanent magnet 23 and the rotor core 22 becomes strong, contributing to the improvement of the rigidity of the entire rotor 20.

[0038] Also, the results of various comparative studies on the shapes and arrangements of the permanent magnets 23 of the rotor 20 are shown below. First, the results of a comparative study on the total widths W1 and W2 of the straight portions 23a of the permanent magnets 23 of adjacent poles are shown. The total width W1 is the total of the straight portions 23a that are joined between adjacent poles on the side without the inter-pole bridge portion 22f (or the inter-pole bridge piece 33). The total width W2 is the total of the straight portions 23a of adjacent poles including the width of its own side where the inter-pole bridge portion 22f (or the inter-pole bridge piece 33) exists. Fig. 7 shows the configuration of the present case. The straight portions 23a of the permanent magnets 23 of the same pole are set to have the same width, and due to the interposition of the inter-pole bridge portion 22f, the total width W2 is larger than the total width W1 (W1 < W2). On the other hand, Fig. 8 shows the configuration of Comparative Example 1, and Fig. 9 shows the configuration of Comparative Example 2. In Comparative Example 1 and Comparative Example 2, the straight portion 23a on the side where the inter-pole bridge portion 22f exists is made narrow, and in Comparative Example 1, the total width W2 and the total width W1 are set to be the same (W1 = W2), and in Comparative Example 2, the total width W1 is set to be larger than the total width W2 (W1 > W2).

[0039] Figure 10 shows the torque fluctuations of the rotating electric machine M. In FIG. 10, the magnitude of the cogging torque when there is no power supply appears. In the present invention where the total widths W1 and W2 are set to "W1 < W2", it can be seen that the cogging torque of the rotating electric machine M is most suppressed. On the other hand, in Comparative Example 2 where the total widths W1 and W2 are set to "W1 > W2", the cogging torque slightly increases, and in Comparative Example 1 where the total widths W1 and W2 are set to "W1 = W2", the cogging torque slightly increases compared to Comparative Example 2.

[0040] Regarding FIG. 11, the torque fluctuations of the rotating electric machine M are also shown. In FIG. 11, the magnitude of the torque ripple during power supply appears. In the present invention where the total widths W1 and W2 are set to "W1 < W2", it can be seen that a large torque is obtained in the rotating electric machine M and the torque ripple is sufficiently suppressed. On the other hand, in Comparative Example 1 where the total widths W1 and W2 are set to "W1 = W2", although a slightly larger torque than the present invention can be obtained, the torque ripple slightly increases. Also, in Comparative Example 2 where the total widths W1 and W2 are set to "W1 > W2", the torque is slightly smaller compared to the present invention, and the torque ripple also slightly increases. Since both Comparative Examples 1 and 2 are fully acceptable, the settings of Comparative Examples 1 and 2 may be adopted.

[0041] Next, various comparative studies were conducted on the presence and shape of the tapered portions 31e, 31f, 32d, and 32e of the first and second magnet through-holes 31 and 32 that constitute each magnet accommodation hole 24. That is, it is various comparative studies on the presence and shape of the tapered portion 23c at the corner of each permanent magnet 23.

[0042] Figure 12 shows the torque ripple ratio of the rotating electric machine M. In the present invention where the tapered portion 23c is provided at the corner of each permanent magnet 23, the ripple ratio is suppressed compared to a comparative example (not shown) where the tapered portion is not provided. Since the comparative example where the tapered portion is not provided is also fully acceptable, a configuration where the tapered portion is not provided may be adopted.

[0043] Figure 13 also shows the torque ripple rate of the rotating electric machine M. This shows the results of a comparative study of whether the size (referred to as taper amount in Figure 13) of the tapered portions 23c provided at the corners of each permanent magnet 23 is the same or different in the axial direction. In this proposal, in which the size of the tapered portions 23c provided at the corners of each permanent magnet 23 is different in the axial direction, the ripple rate is reduced compared to a comparative example (not shown) in which the size of the tapered portions is the same in the axial direction. Note that the comparative example in which the size of the tapered portions is the same in the axial direction is also fully acceptable, so a configuration in which the size of the tapered portions is the same in the axial direction may also be adopted.

[0044] [Effects of this embodiment] The effects of this embodiment will be described. (1) The outer core portion 25, surrounded by the magnet accommodating holes 24 and the permanent magnets 23, is supported by three support points on the periphery of the rotor core 22: the pair of outer bridge portions 22d, 22e and the reinforcing bridge portion 22c. In each core sheet 30, one outer core portion 25 is constructed by mixing an outer core portion 34a supported by two of the outer bridge pieces 31c and the reinforcing bridge piece 31d and an outer core portion 34b supported by only one of the outer bridge pieces 32c. When multiple core sheets 30 are stacked to form the rotor core 22, the outer core portion 25 is supported by three support points: the outer bridge portions 22d, 22e and the reinforcing bridge portion 22c in this embodiment. The support rigidity of the outer core portion 25 supported by the multiple bridge portions 22d, 22e, and 22c is sufficiently high, ensuring the centrifugal strength of the rotor 20. On the other hand, by mixing the outer core portions 34b supported by one outer bridge piece 32c, the individual bridge pieces 31c, 32c, 31d constituting the bridge portions 22d, 22e, 22c supporting the outer core portion 25 are appropriately thinned out, which makes it possible to reduce leakage flux, which is a concern in each bridge portion 22d, 22e, 22c.

[0045] The peripheral bridge portions 22d and 22e correspond to the first and second bridge portions, and the reinforcing bridge portion 22c corresponds to the third bridge portion. The peripheral bridge pieces 31c and 32c correspond to the first and second bridge pieces, and the reinforcing bridge piece 31d corresponds to the third bridge piece.

[0046] (2) In the core sheet 30, first magnet through holes 31 having outer periphery bridge pieces 31c and reinforcing bridge pieces 31d and second magnet through holes 32 having outer periphery bridge pieces 32c are arranged alternately in the circumferential direction and mixed together on one sheet. The rotor core 22 is configured by rotating and stacking the core sheets 30 so that every predetermined number of core sheets 30, or every single sheet in this embodiment, forms a magnet accommodating hole 24 having a mixture of first and second magnet through holes 31, 32. In other words, the rotor core 22 of this embodiment can be configured using one type of core sheet 30, and can be easily realized.

[0047] (3) The rotor core 22 is formed by rotating the same number of core sheets 30 at a time, or one sheet at a time in this embodiment, and stacking the core sheets 30. This is expected to improve the rotational balance of the rotor 20 that uses the rotor core 22.

[0048] (4) The rotor core 22 has an inter-pole bridge portion 22f between the magnet accommodating holes 24 of adjacent magnetic pole portions 26. The core sheet 30 has an inter-pole bridge piece 33 between the first and second magnet through holes 31, 32 on one adjacent side, and on the other adjacent side, the inter-pole bridge piece 33 is eliminated, connecting the first and second magnet through holes 31, 32 to each other. In this configuration, the outer periphery bridge pieces 31c, 32c are provided only on the side where the inter-pole bridge piece 33 is present. In other words, the inter-pole bridge piece 33 and the outer periphery bridge pieces 31c, 32c are connected to each other and support each other, making this a rational configuration.

[0049] The inter-electrode bridge portion 22f corresponds to the fourth bridge portion, and the inter-electrode bridge piece 33 corresponds to the fourth bridge piece. (5) The total width W1 of the straight portions 23a of adjacent permanent magnets 23 that are connected to each other on the side without the inter-pole bridge portion 22f is set to be different from the total width W2 of the straight portions 23a including the inter-pole bridge portion 22f on the side with the inter-pole bridge portion 22f. In particular, in this embodiment, the total width W2 is set to be larger than the total width W1. This is expected to have the effect of sufficiently suppressing both the cogging torque and torque ripple of the rotating electric machine M.

[0050] The straight portions 23a of adjacent permanent magnets 23 correspond to the juxtaposed portions of the adjacent permanent magnets 23. The total width W1 corresponds to the first total width, and the total width W2 corresponds to the second total width. (6) The permanent magnet 23 has tapered portions 23c at the corners of the outer peripheral end of the rotor core 22. In particular, in this embodiment, the tapered portions 23c at the corners of the pair of linear portions 23a are set to have different sizes. This is also expected to have the effect of sufficiently suppressing torque ripple in the rotating electric machine M.

[0051] (7) The first magnet through hole 31 is positioned offset circumferentially to one side with respect to the magnetic pole center line Ls of the magnetic pole portion 26, and the second magnet through hole 32 is positioned offset circumferentially to the other side with respect to the magnetic pole center line Ls. The first and second magnet through holes 31, 32 are each configured with an asymmetric V-shaped folded shape with respect to the magnetic pole center line Ls. The magnet accommodating hole 24 is configured with a concave-convex inner surface due to the mixture of the first and second magnet through holes 31, 32. Therefore, the permanent magnet 23 manufactured by injection molding into the magnet accommodating hole 24 as in this embodiment has a portion thereof inserted into the concave-convex portion of the inner surface of the magnet accommodating hole 24, thereby providing a strong bond between the magnets. The strong bond between the permanent magnet 23 and the rotor core 22 contributes to improving the rigidity of the entire rotor 20.

[0052] [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.

[0053] The above-described comparative examples are also modified examples, and may be appropriately modified like the various comparative examples. In addition, the above-described embodiment and the various comparative examples may be appropriately combined and implemented. The shapes of the magnet accommodating hole 24 and the first and second magnet through holes 31, 32 are examples and may be changed as appropriate. In this case, the shape of the permanent magnet 23 produced by injection molding into the magnet accommodating hole 24 will also be changed.

[0054] In the above embodiment, the main shapes of the permanent magnets 23 of adjacent magnetic pole portions 26 are configured symmetrically with respect to the magnetic pole boundary line Ld. The main shapes of the permanent magnets 23 refer to the approximate shapes excluding the bridge portions 22c, 22d, and 22e of the magnet accommodating holes 24 and the tapered portions 23c. However, as shown in FIG. 14, the main shapes of the permanent magnets 23 of adjacent magnetic pole portions 26 may be made different so that they are asymmetric with respect to the magnetic pole boundary line Ld. In FIG. 14, as an example, the widths of the pair of linear portions 23a of the permanent magnets 23 of the magnetic pole portion 26 of the second aspect A2 are set to the same width W3, and the widths of the linear portions 23a of the permanent magnets 23 of the magnetic pole portion 26 of the first aspect A1 are set to different widths W4 and W5. This is an example in which the widths of the permanent magnets 23 are made different as a change in the main shapes of the permanent magnets 23.

[0055] 15 and 16 show the cogging torque and torque ripple rate of the rotating electric machine M, respectively. Compared to the above embodiment in which the main shapes of the permanent magnets 23 of adjacent magnetic pole portions 26 are symmetrical with respect to the magnetic pole boundary line Ld, the modified example shown in FIG. 14 in which the main shapes are asymmetrical further reduces both the cogging torque and the ripple rate. Note that the above embodiment employs a symmetrical configuration because the cogging torque and the ripple rate are sufficiently acceptable even with a symmetrical configuration. An asymmetrical configuration, as in the modified example, can also be employed.

[0056] While one outer core portion 25 is supported at three locations, namely, the outer bridge portions 22d, 22e and the reinforcing bridge portion 22c, it may be supported at two locations by omitting one of these locations, or at four or more locations by adding a bridge portion in addition to these. Furthermore, the shapes, arrangements, presence or absence, and combinations of the outer bridge portions 22d, 22e, the reinforcing bridge portion 22c, and the inter-electrode bridge portion 22f, as well as the individual outer bridge pieces 31c, 32c, the reinforcing bridge piece 31d, and the inter-electrode bridge piece 33, may be changed as appropriate.

[0057] While the rotor core 22 is constructed by rotating and stacking the core sheets 30 one by one, it may also be possible to rotate and stack a predetermined number of sheets, two or more at a time. In this case, the number of sheets may be the same or different.

[0058] While the rotor core 22 is configured by laminating multiple core sheets 30 of one type, it may be configured by laminating multiple types of core sheets (not shown). In this case, the core sheets may be stacked with or without rotation.

[0059] The curvature of the outer peripheral surface 26a of each magnetic pole portion 26 is made larger than the curvature that would occur if the outer peripheral surface 22a of the rotor core 22 had a uniform circumference, and the outer peripheral surface 22a of the rotor core 22 is configured to have a wavy shape. However, the outer peripheral surface 22a of the rotor core 22 may also have, for example, a general uniform circumference.

[0060] In the embodiment, the permanent magnet 23 is produced by filling the magnet accommodating hole 24 with magnetic material that will become the permanent magnet 23, but the permanent magnet 23 may be produced in advance and inserted into the magnet accommodating hole 24.

[0061] The number of magnetic poles of the rotor 20, i.e., the number of permanent magnets 23 and magnet accommodating holes 24, may be changed as appropriate. Also, the number of magnetic poles of the stator 10 may be changed as appropriate. In addition to the above, the configuration of the rotating electric machine M may be changed as appropriate.

[0062] 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. [Explanation of symbols]

[0063] M rotating electric machine, 10 stator, 20 rotor, 22 rotor core, 22c reinforcing bridge portion (bridge portion), 22d, 22e outer periphery bridge portion (bridge portion), 23 permanent magnet, 24 magnet accommodating hole, 24c radial outer end portion, 25 outer core portion, 26 magnetic pole portion, 30 core sheet, 31c, 32c outer periphery bridge piece (bridge piece), 31d reinforcing bridge piece (bridge piece), 34a, 34b outer core portion

Claims

1. The rotor core (22) is formed by laminating a plurality of core sheets (30) and has magnet accommodating holes (24) that are folded back to project radially inward, and permanent magnets (23) are provided in the magnet accommodating holes of the rotor core, An embedded magnet rotor (20) including a plurality of magnetic pole portions (26) including the permanent magnets located radially inside the rotor core and an outer core portion (25) that is a part of the rotor core located radially outside the permanent magnets, The outer core portion of the rotor core is formed by laminating the outer core portions (34a, 34b) of the individual core sheets, and is supported at a peripheral portion of the rotor core by a plurality of bridge portions (22d, 22e, 22c) including bridge portions located on at least one side of a pair of radially outer end portions (24c) of the folded-back magnet accommodating holes, At least the outer core portion (34b) supported by one bridge piece (32c) of the core sheet constituting the bridge portion (22e) at the radially outer end portion on one side is mixed, and a plurality of the core sheets are stacked to establish a support mode for the outer core portion by the bridge portions at the plurality of locations, The permanent magnet has a tapered portion (23c) at each corner of the outer peripheral end of the rotor core, which has the folded shape, and the tapered portions provided at each corner of the outer peripheral end of the rotor core are set to have different sizes, and the tapered portions are configured to have different sizes in the axial direction.

2. The outer core portion of the rotor core is supported relative to the periphery of the rotor core at at least three locations: first and second bridge portions (22d, 22e) provided at a pair of radially outer ends of the folded-back magnet accommodating hole, and a third bridge portion (22c) provided so as to cross the magnet accommodating hole at a midpoint of the hole; The rotor of claim 1, wherein the individual outer core portions supported by one or two of the first to third bridge pieces (31c, 32c, 31d) of the core sheet constituting the first to third bridge portions are mixed together, and a plurality of the core sheets are stacked to establish a support pattern for the outer core portions by at least three points of the first to third bridge portions.

3. The core sheet is provided with a mixture of first magnet through holes (31) having two bridge pieces (31c, 31d) of the first to third bridge pieces and second magnet through holes (32) having the remaining bridge piece (32c) that is not in the first magnet through hole, alternately arranged in the circumferential direction, on one sheet; 3. The rotor core according to claim 2, wherein the rotor core is formed by using a plurality of core sheets of the same configuration, and the core sheets are rotated and stacked so that every predetermined number of the core sheets form the magnet accommodating holes in which the first and second magnet through holes are mixed.

4. The rotor according to claim 3 , wherein the rotor core is formed by rotating the core sheets every equal number of sheets.

5. The rotor core has a fourth bridge portion (22f) between the magnet accommodating holes of the adjacent magnetic pole portions, the core sheet has a fourth bridge piece (33) for forming the fourth bridge portion between the first and second magnet through holes on one adjacent side, and is configured so that the first and second magnet through holes are connected to each other without the fourth bridge piece between the first and second magnet through holes on the other adjacent side, 5. The rotor according to claim 3, wherein the first and second bridge pieces are provided only on the side where the fourth bridge piece is present.

6. 6. The rotor according to claim 5, wherein the total widths (W1, W2) of adjacent juxtaposed portions (23a) of adjacent permanent magnets are set so that a first total width (W1) of the juxtaposed portions that join each other on the side without the fourth bridge portion is different from a second total width (W2) of the juxtaposed portions that include the fourth bridge portion on the side with the fourth bridge portion.

7. 7. The rotor according to claim 6, wherein the second total width on the side with the fourth bridge portion is set to be larger than the first total width on the side without the fourth bridge portion.

8. the first magnet through hole is disposed at a position offset to one side in the circumferential direction with respect to the magnetic pole center line (Ls) of the magnetic pole portion, the second magnet through hole is disposed at a position offset to the other side in the circumferential direction with respect to the magnetic pole center line, and the first and second magnet through holes are each configured such that the folded shapes are asymmetric with respect to the magnetic pole center line, The rotor according to any one of claims 3 to 7, wherein the magnet accommodating hole has an inner surface that is uneven due to the presence of a mixture of the first and second magnet through holes.

9. The rotor according to any one of claims 1 to 8, wherein the permanent magnets have a main shape configured asymmetrically with respect to a magnetic boundary line (Ld) of the adjacent magnetic pole portion.

10. an embedded magnet rotor (20) including a rotor core (22) formed by laminating a plurality of core sheets (30) and having magnet accommodating holes (24) that are folded back to convexly inward in the radial direction, and permanent magnets (23) provided in the magnet accommodating holes of the rotor core, the permanent magnets being positioned radially inward of the rotor core, and an outer core portion (25) that is a part of the rotor core being positioned radially outward of the permanent magnets, and a plurality of magnetic pole portions (26) being configured; a stator (10) that applies a rotating magnetic field to the rotor; A rotating electric machine (M) comprising: The outer core portion of the rotor core is formed by laminating the outer core portions (34a, 34b) of the individual core sheets, and is supported at a peripheral portion of the rotor core by a plurality of bridge portions (22d, 22e, 22c) including bridge portions located on at least one side of a pair of radially outer end portions (24c) of the folded-back magnet accommodating holes, At least the outer core portion (34b) supported by one bridge piece (32c) of the core sheet constituting the bridge portion (22e) at the radially outer end portion on one side is mixed, and a plurality of the core sheets are stacked to establish a support mode for the outer core portion by the bridge portions at the plurality of locations, The permanent magnet has a tapered portion (23c) at each corner of the outer peripheral end of the rotor core, which has the folded shape, and the tapered portions provided at each corner of the outer peripheral end of the rotor core are set to have different sizes, and the tapered portions are configured to have different sizes in the axial direction.

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