Rotor
The rotor design with aligned accommodating holes and a radial connecting portion addresses the issue of increased distance and flux leakage by dispersing centrifugal forces, improving brushless motor performance.
Patent Information
- Application Number
- JP2024081774
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-05-20
- Publication Date
- 2025-12-03
AI Technical Summary
The conventional embedded magnet rotor design results in an increased distance between the rotor core's outer surface and the magnet, which degrades the performance of the brushless motor due to centrifugal forces and potential magnetic flux leakage.
The rotor design incorporates a rotor core with aligned first and second accommodating holes in the tangential direction, connected by a radial connecting portion, and divides the magnet into two parts housed in these holes, ensuring rigidity and dispersing centrifugal forces, thereby maintaining a shorter distance between the rotor core and magnet.
This design prevents the distance between the rotor core's outer surface and the magnet from becoming excessively long, enhancing motor performance by reducing magnetic flux leakage and maintaining structural integrity under centrifugal forces.
Smart Images
Figure 2025175593000001_ABST
Abstract
Description
[Technical Field]
[0001] The technology of the present disclosure relates to a rotor, and more particularly to an embedded magnet rotor. [Background technology]
[0002] Conventionally, an embedded magnet rotor is known that includes a rotor core and a magnet embedded in the rotor core (see, for example, Patent Document 1). In this rotor, the rotor core has an accommodating hole located closer to the outer circumferential surface of the rotor core than the center of the rotor core, and the magnet is accommodated in the accommodating hole. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Publication No. 2023-027913 Summary of the Invention [Problem to be solved by the invention]
[0004] When the rotor rotates, centrifugal force acts on the magnet. Therefore, in order to hold the magnet, it is conceivable to ensure a sufficient thickness for the portion of the rotor core radially outside the accommodating hole to ensure a holding force for the magnet. However, in this case, the distance between the outer surface of the rotor core and the magnet becomes longer, which in turn increases the distance between the stator, which is located radially outside the rotor, and the magnet, which may degrade the performance of the brushless motor. Therefore, there is room for improvement in preventing the distance between the outer surface of the rotor core and the magnet from becoming longer.
[0005] The technique disclosed herein provides a rotor that can prevent the distance between the outer peripheral surface of the rotor core and the magnet from becoming long. [Means for solving the problem]
[0006] The technology disclosed herein is a rotor (10) comprising a rotor core (12) and a magnet (14) embedded in the rotor core, the rotor core having an accommodating hole (18) located closer to the outer surface of the rotor core than the center of the rotor core, the accommodating hole having a first accommodating hole (18A) and a second accommodating hole (18B) aligned in a tangential direction of the rotor core, a connecting portion (22) extending radially of the rotor core between the first accommodating hole and the second accommodating hole in the tangential direction of the rotor core and connecting a portion (12B) outer than the accommodating hole and a portion (12C) inner than the accommodating hole in the radial direction of the rotor core, and the magnet having a first magnet (14A) accommodated in the first accommodating hole and a second magnet (14B) accommodated in the second accommodating hole.
[0007] According to the technique of the present disclosure, a rotor is provided that can prevent the distance between the outer peripheral surface of the rotor core and the magnet from becoming long. [Brief explanation of the drawings]
[0008] [Figure 1] FIG. 2 is a plan view of a rotor according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged plan view of the rotor core in a portion A of FIG. [Figure 3] FIG. 2 is an enlarged plan view of the rotor of part A in FIG. [Figure 4] FIG. 10 is an enlarged plan view of a main portion of a rotor according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION
[0009] Hereinafter, one embodiment of the present disclosure will be described.
[0010] The rotor 10 according to this embodiment shown in Fig. 1 is an interior permanent magnet (IPM) rotor used in an inner rotor brushless motor. The rotor 10 includes a rotor core 12 and a plurality of magnets 14. The magnets 14 are embedded in the rotor core 12.
[0011] The rotor core 12 is a laminated body formed by stacking a plurality of core sheets in the axial direction of the rotor core 12. The outer peripheral surface 12A of the rotor core 12 is formed in a circular shape when viewed from the axial direction of the rotor core 12.
[0012] The rotor core 12 has an insertion hole 16 and a plurality of accommodating holes 18. The insertion hole 16 and the plurality of accommodating holes 18 penetrate the rotor core 12 in the axial direction. A shaft is inserted into the insertion hole 16. The insertion hole 16 is formed in the center of the rotor core 12.
[0013] The multiple accommodating holes 18 are aligned in the circumferential direction of the rotor core 12 along the outer peripheral surface 12A of the rotor core 12. Each accommodating hole 18 is located closer to the outer peripheral surface 12A than the center of the rotor core 12. As will be described later, arranging the magnets 14 accommodated in the accommodating holes 18 closer to the stator, which is located radially outward of the rotor 10, improves the performance of the brushless motor. Therefore, the accommodating holes 18 are formed at positions closer to the outer peripheral surface 12A of the rotor core 12.
[0014] Each accommodating hole 18 has a first accommodating hole 18A and a second accommodating hole 18B that are aligned in the tangential direction of the rotor core 12. The first accommodating hole 18A and the second accommodating hole 18B each extend with the tangential direction of the rotor core 12 being the width direction. A connecting portion 22 is provided between the first accommodating hole 18A and the second accommodating hole 18B in the tangential direction of the rotor core 12. The connecting portion 22 extends in the radial direction of the rotor core 12 and connects a portion 12B that is outer than the accommodating hole 18 to a portion 12C that is inner than the accommodating hole 18 in the radial direction of the rotor core 12.
[0015] Each magnet 14 has a first magnet 14A housed in a first housing hole 18A and a second magnet 14B housed in a second housing hole 18B. The first magnet 14A and the second magnet 14B are each formed in a flat plate shape and extend in the tangent direction of the rotor core 12 as the width direction.
[0016] Each magnet 14 functions as a single magnet by combining a first magnet 14A and a second magnet 14B. The magnetic pole (e.g., N pole) of one of the adjacent magnets 14 on the outer circumferential surface 12A side is set to a different magnetic pole from the magnetic pole (e.g., S pole) of the other of the adjacent magnets 14 on the outer circumferential surface 12A side.
[0017] In each magnet 14, the half of the first magnet 14A facing the outer circumferential surface 12A is formed by one of the N and S poles (for example, the N pole), and the half of the first magnet 14A opposite the outer circumferential surface 12A is formed by the other of the N and S poles (for example, the S pole). In each magnet 14, the half of the second magnet 14B facing the outer circumferential surface 12A is set to the same magnetic pole (for example, the N pole) as the half of the first magnet 14A facing the outer circumferential surface 12A, and the half of the second magnet 14B opposite the outer circumferential surface 12A is set to the same magnetic pole (for example, the S pole) as the half of the first magnet 14A facing the outer circumferential surface 12A.
[0018] 2, the inner surface of first accommodating hole 18A, more specifically, has a first outer side surface 19A, a first inner side surface 19B, and a first lateral side surface 19C. First outer side surface 19A is the surface of the inner surface of first accommodating hole 18A that is located on the outer peripheral surface 12A side, first inner side surface 19B is the surface of the inner surface of first accommodating hole 18A that is located on the opposite side from outer peripheral surface 12A (i.e., the side toward the center of rotor core 12), and first lateral side surface 19C is the surface that is located on one side in the lateral width direction of first accommodating hole 18A.
[0019] Similarly, the inner surface of second accommodating hole 18B, more specifically, has a second outer side surface 20A, a second inner side surface 20B, and a second lateral side surface 20C. Second outer side surface 20A is the surface of the inner surface of second accommodating hole 18B that is located on the outer peripheral surface 12A side, second inner side surface 20B is the surface of the inner surface of second accommodating hole 18B that is located on the opposite side from outer peripheral surface 12A (i.e., the side toward the center of rotor core 12), and second lateral side surface 20C is the surface that is located on the other side in the lateral width direction of second accommodating hole 18B.
[0020] A first recess 28A is formed in the first inner surface 19B, and a second recess 28B is formed in the second inner surface 20B. The first recess 28A and the second recess 28B are formed in a recessed shape that is recessed on the opposite side from the outer peripheral surface 12A. The first recess 28A is formed at one end of the first inner surface 19B in the width direction of the first accommodating hole 18A, and the second recess 28B is formed at the other end of the second inner surface 20B in the width direction of the second accommodating hole 18B.
[0021] 3, one end of the first inner surface 19B in the width direction of the first accommodating hole 18A corresponds to a portion of the first inner surface 19B corresponding to one end 15A of the first magnet 14A in the width direction, and the other end of the second inner surface 20B in the width direction of the second accommodating hole 18B corresponds to a portion of the second inner surface 20B corresponding to the other end 15B of the second magnet 14B in the width direction. That is, the first recess 28A is formed in a portion of the first inner surface 19B corresponding to one end 15A of the first magnet 14A in the width direction, and the second recess 28B is formed in a portion of the second inner surface 20B corresponding to the other end 15B of the second magnet 14B in the width direction. The first recess 28A and the second recess 28B are formed to prevent the ends 15A, 15B (especially the corners) of the first magnet 14A and the second magnet 14B from interfering with the first inner surface 19B and the second inner surface 20B.
[0022] Additionally, a first flux barrier 30A is formed on the first lateral side surface 19C, and a second flux barrier 30B is formed on the second lateral side surface 20C. The first flux barrier 30A is formed in a concave shape recessed away from the first magnet 14A toward one circumferential side of the rotor core 12, and the second flux barrier 30B is formed in a concave shape recessed away from the second magnet 14B toward the other circumferential side of the rotor core 12. The first flux barrier 30A is a groove for creating a gap that prevents magnetic flux from passing from the north pole to the south pole of the first magnet 14A. Similarly, the second flux barrier 30B is a groove for creating a gap that prevents magnetic flux from passing from the north pole to the south pole of the second magnet 14B.
[0023] Next, the effects of this embodiment will be described.
[0024] First, to clarify the effects of this embodiment, a comparative example will be described. As shown in Fig. 4, in the comparative example, the connecting portion 22 is omitted, and the accommodating hole 18 is configured such that the first accommodating hole 18A and the second accommodating hole 18B (see Fig. 3) are connected. Also, the magnet 14 is configured such that the first magnet 14A and the second magnet 14B (see Fig. 3) are integrated.
[0025] In the comparative example, when rotor 10 rotates, centrifugal force F acts on magnet 14. Therefore, in order to hold magnet 14, it is conceivable to ensure the thickness of portion 12B of rotor core 12 radially outward of accommodating hole 18 to ensure a holding force for magnet 14. However, in this case, the distance between outer peripheral surface 12A of rotor core 12 and magnet 14 becomes longer, which in turn increases the distance between magnet 14 and the stator disposed radially outward of rotor 10, which may result in a deterioration in the performance of the brushless motor.
[0026] Furthermore, the centrifugal force F is greatest at the widthwise center of the magnet 14, and the widthwise center of the outer surface of the accommodating hole 18 is pressed radially outward by the centrifugal force. Therefore, it is necessary to suppress deformation of the widthwise center of the outer surface of the accommodating hole 18. In order to suppress deformation of the widthwise center of the outer surface of the accommodating hole 18, it is possible to increase the thickness of a portion 12D between the outer peripheral surface 12A of the rotor core 12 and the first flux barrier 30A and a portion 12E between the outer peripheral surface 12A of the rotor core 12 and the second flux barrier 30B. However, in this case, there is a risk that magnetic flux leaking from the north pole to the south pole of the magnet 14 via the portion 12D between the outer peripheral surface 12A of the rotor core 12 and the first flux barrier 30A and the portion 12E between the outer peripheral surface 12A of the rotor core 12 and the second flux barrier 30B may increase.
[0027] 3, in the rotor 10 according to this embodiment, the accommodating hole 18 has a first accommodating hole 18A and a second accommodating hole 18B aligned in the tangential direction of the rotor core 12, and a connecting portion 22 extending in the radial direction of the rotor core 12 is provided between the first accommodating hole 18A and the second accommodating hole 18B in the tangential direction of the rotor core 12 to connect a portion 12B located outside the accommodating hole 18 to a portion 12C located inside the accommodating hole 18 in the radial direction of the rotor core 12. Therefore, by connecting the portion 12B located outside the accommodating hole 18 to the portion 12C located inside the accommodating hole 18 by the connecting portion 22, the rigidity of the portion 12B located outside the accommodating hole 18 can be ensured.
[0028] Furthermore, the magnet 14 has a first magnet 14A housed in the first housing hole 18A and a second magnet 14B housed in the second housing hole 18B. In other words, the magnet 14 is divided into the first magnet 14A and the second magnet 14B. Therefore, the centrifugal force F acting on each of the first magnet 14A and the second magnet 14B can be dispersed.
[0029] As a result, it is possible to ensure a holding force for first magnet 14A and second magnet 14B. Therefore, compared to a case where connecting portion 22 is not provided, it is not necessary to ensure a thickness for portion 12B outside accommodating hole 18, and therefore it is possible to prevent the distance between outer peripheral surface 12A of rotor core 12 and magnet 14 from becoming long.
[0030] Furthermore, by reducing the thickness of portion 12B outside of accommodating hole 18, it is possible to reduce the thickness of portion 12D between outer peripheral surface 12A of rotor core 12 and first flux barrier 30A, for example, to the manufacturing limit. This makes it possible to prevent magnetic flux from leaking from the north pole to the south pole of first magnet 14A through portion 12D between outer peripheral surface 12A of rotor core 12 and first flux barrier 30A. Similarly, by reducing the thickness of portion 12B outside of accommodating hole 18, it is possible to reduce the thickness of portion 12E between outer peripheral surface 12A of rotor core 12 and second flux barrier 30B, for example, to the manufacturing limit. This makes it possible to prevent magnetic flux from leaking from the north pole to the south pole of second magnet 14B through portion 12E between outer peripheral surface 12A of rotor core 12 and second flux barrier 30B.
[0031] The above describes one embodiment of the technology of the present disclosure, but the present invention is not limited to the above, and it goes without saying that the present invention can be implemented in various modifications within the scope of the gist of the present disclosure.
[0032] Below, supplementary notes are provided regarding the technology of the present disclosure. (Appendix 1) A rotor core (12); a magnet (14) embedded in the rotor core; Equipped with The rotor core has an accommodating hole (18) located closer to the outer circumferential surface of the rotor core than the center of the rotor core, The accommodating holes include a first accommodating hole (18A) and a second accommodating hole (18B) aligned in a tangential direction of the rotor core, a connecting portion (22) extending in a radial direction of the rotor core is provided between the first accommodating hole and the second accommodating hole in a tangential direction of the rotor core, the connecting portion (22) connecting a portion (12B) outer than the accommodating hole and a portion (12C) inner than the accommodating hole in the radial direction of the rotor core, The magnet includes a first magnet (14A) accommodated in the first accommodating hole and a second magnet (14B) accommodated in the second accommodating hole. Rotor (10). [Explanation of symbols]
[0033] 10...rotor, 12...rotor core, 12A...outer peripheral surface, 12B...portion of rotor core radially outer than the accommodating hole, 12C...portion of rotor core radially inner than the accommodating hole, 12D...portion between the outer peripheral surface of rotor core and first flux barrier, 12E...portion between the outer peripheral surface of rotor core and second flux barrier, 14...magnet, 14A...first magnet, 14B...second magnet, 15A...end, 15B...end, 16...insertion hole, 18...accommodating hole, 18A...first accommodating hole, 18B...second accommodating hole, 19A...first outer surface, 19B...first inner surface, 19C...first lateral surface, 20A...second outer surface, 20B...second inner surface, 20C...second lateral surface, 22...connecting portion, 28A...first recess, 28B...second recess, 30A...first flux barrier, 30B...second flux barrier
Claims
[Claim 1] A rotor core (12); a magnet (14) embedded in the rotor core; Equipped with The rotor core has an accommodating hole (18) located closer to the outer circumferential surface (12A) of the rotor core than the center of the rotor core, The accommodating holes include a first accommodating hole (18A) and a second accommodating hole (18B) aligned in a tangential direction of the rotor core, a connecting portion (22) extending in a radial direction of the rotor core is provided between the first accommodating hole and the second accommodating hole in a tangential direction of the rotor core, the connecting portion (22) connecting a portion (12B) outer than the accommodating hole and a portion (12C) inner than the accommodating hole in the radial direction of the rotor core, The magnet includes a first magnet (14A) accommodated in the first accommodating hole and a second magnet (14B) accommodated in the second accommodating hole. Rotor (10).
Citation Information
Patent Citations
Rotor of rotary electric machine and manufacturing method of the same
JP2023027913A