Rotor

Abstract

To provide a rotor capable of increasing reluctance torque without decreasing magnet torque.SOLUTION: A rotor (10) has a rotor core (12) and a magnet (14) arranged in a circumferential direction of the rotor core and embedded in the rotor core. On a periphery part of an end face in an axial direction of the rotor core, a plurality of projection parts (20) located between adjacent magnets in the circumferential direction of the rotor core respectively and projecting in the axial direction of the rotor core are provided.SELECTED DRAWING: Figure 1

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). This type of rotor is combined with a stator disposed radially outside the rotor to form a brushless motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-112197 Summary of the Invention [Problem to be solved by the invention]

[0004] In this type of brushless motor, when controlling rotor rotation without a sensor, it is necessary to increase the reluctance torque to ensure a sufficient salient pole ratio. The salient pole ratio is the ratio (Ld / Lq) of the d-axis reactance Ld to the q-axis inductance Lq. If the magnet position is shifted radially inward of the rotor to increase the reluctance torque, the distance between the rotor and stator increases, reducing the magnetic torque and leading to a decrease in motor output. Therefore, it is necessary to increase the reluctance torque without reducing the magnetic torque.

[0005] The technique of the present disclosure provides a rotor that can increase reluctance torque without reducing magnet torque. [Means for solving the problem]

[0006] The technology disclosed herein is a rotor (10) comprising a rotor core (12) and magnets (14) arranged circumferentially around the rotor core and embedded in the rotor core, and the rotor core has a plurality of protrusions (20) on the outer periphery of its axial end face, each of which is positioned between adjacent magnets in the circumferential direction of the rotor core and protruding in the axial direction of the rotor core.

[0007] According to the technique of the present disclosure, a rotor is provided that can increase reluctance torque without reducing magnet torque. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B are two-views (top and side views) 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. 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 embedded magnet rotor used in an inner rotor brushless motor. The rotor 10 includes a rotor core 12 and a plurality of magnets 14. The plurality of 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 magnet 14 is housed in a housing hole 18. Each magnet 14 is formed in a flat plate shape and extends with the tangential direction of the rotor core 12 as the width direction. Half of each magnet 14 on the outer peripheral surface 12A side is formed by one of the N and S poles (e.g., N pole), and half of each magnet 14 opposite the outer peripheral surface 12A is formed by the other of the N and S poles (e.g., S pole). The magnetic pole (e.g., N pole) of the half of each magnet 14 on the outer peripheral surface 12A side of one of the adjacent magnets 14 is set to a different magnetic pole from the magnetic pole (e.g., S pole) of the half of each magnet 14 on the outer peripheral surface 12A side of the other of the adjacent magnets 14.

[0015] A plurality of protrusions 20 are provided on the outer periphery of the end face on one axial side of rotor core 12. Each of the plurality of protrusions 20 is located between adjacent magnets 14 in the circumferential direction of rotor core 12 (in other words, between adjacent accommodating holes 18), and protrudes toward one axial side of rotor core 12. Similarly, a plurality of protrusions 20 are also provided on the outer periphery of the end face on the other axial side of rotor core 12. Each of the plurality of protrusions 20 is located between adjacent magnets 14 in the circumferential direction of rotor core 12 (in other words, between adjacent accommodating holes 18), and protrudes toward the other axial side of rotor core 12.

[0016] The multiple protrusions 20 provided on the end face on one axial side of the rotor core 12 are integrally formed on one of the multiple core sheets constituting the rotor core 12, that is, one end core sheet 22, which is provided on the end of the rotor core 12 on one axial side. The one end core sheet 22 is formed by punching so that the multiple protrusions 20 protrude radially outward from the one end core sheet 22, and the multiple protrusions 20 are formed by bending so that they protrude from the radially outward direction of the one end core sheet 22 to one axial side of the rotor core 12. The multiple protrusions 20 provided on the end face on one axial side of the rotor core 12 are an example of the "multiple first protrusions."

[0017] Similarly, the multiple protrusions 20 provided on the end face on the other axial side of the rotor core 12 are integrally formed on one of the multiple core sheets constituting the rotor core 12, that is, the other end core sheet 22, which is provided at the end of the rotor core 12 on the other axial side. The other end core sheet 22 is formed by punching so that the multiple protrusions 20 protrude radially outward from the other end core sheet 22, and the multiple protrusions 20 are formed by bending so that they protrude from the radially outward direction of the other end core sheet 22 to the other axial side of the rotor core 12. The multiple protrusions 20 provided on the end face on the other axial side of the rotor core 12 are an example of the "multiple second protrusions."

[0018] 2 and 3, the inner surface of the accommodating hole 18 more specifically has an outer surface 18A, an inner surface 18B, and a pair of lateral surfaces 18C. The outer surface 18A is the surface of the inner surface of the accommodating hole 18 that is located on the outer peripheral surface 12A side, the inner surface 18B is the surface of the inner surface of the accommodating hole 18 that is located on the opposite side from the outer peripheral surface 12A (i.e., on the central side of the rotor core 12), and the pair of lateral surfaces 18C are surfaces that are located on both sides of the accommodating hole 18 in the lateral width direction.

[0019] A pair of recesses 24 are formed in the inner surface 18B. Each recess 24 is formed in a concave shape recessed on the opposite side from the outer peripheral surface 12A. Each recess 24 is formed at each end on both sides of the inner surface 18B in the width direction of the accommodating hole 18. The ends on both sides of the inner surface 18B in the width direction of the accommodating hole 18 correspond to the portions of the inner surface 18B corresponding to the ends 14A of the magnet 14 in the width direction. In other words, each recess 24 is formed in a portion of the inner surface 18B corresponding to the ends 14A of the magnet 14 in the width direction. The recesses 24 are formed to prevent the ends 14A (especially corners) of the magnet 14 in the width direction from interfering with the inner surface 18B.

[0020] Additionally, a flux barrier 26 is formed on each lateral side surface 18C. Each flux barrier 26 is formed in a concave shape recessed on the side away from the magnet 14 along the circumferential direction of the rotor core 12. The flux barrier 26 is a groove for ensuring a gap that prevents magnetic flux from passing from the north pole to the south pole of the magnet 14.

[0021] Next, the effects of this embodiment will be described.

[0022] In a brushless motor equipped with an interior permanent magnet rotor 10, the d-axis magnetic flux φd is proportional to the magnet torque, and the q-axis magnetic flux φq is proportional to the reluctance torque. There is a trade-off between the d-axis magnetic flux φd and the q-axis magnetic flux φq with respect to the arrangement of the magnet 14. In order to increase the reluctance torque without reducing the magnet torque, it is necessary to increase only the q-axis magnetic flux φq.

[0023] In this regard, in the rotor 10 according to this embodiment, the outer periphery of the end face on one axial side of the rotor core 12 is provided with a plurality of protrusions 20 that are positioned between adjacent magnets 14 in the circumferential direction of the rotor core 12 and protrude in the axial direction of the rotor core 12. Similarly, the outer periphery of the end face on the other axial side of the rotor core 12 is provided with a plurality of protrusions 20 that are positioned between adjacent magnets 14 in the circumferential direction of the rotor core 12 and protrude in the axial direction of the rotor core 12. Therefore, axial leakage magnetic flux from the stator can be guided between adjacent magnets 14 via the protrusions 20, thereby increasing the q-axis magnetic flux φq and, ultimately, the reluctance torque. Furthermore, since it is not necessary to shift the position of the magnets 14 radially inward of the rotor 10, there is no need to reduce the magnet torque.

[0024] In this way, according to the rotor 10 according to this embodiment, it is possible to increase the reluctance torque without reducing the magnet torque.

[0025] Furthermore, the multiple protrusions 20 provided on the end face on one axial side of the rotor core 12 are formed integrally with one of the multiple core sheets constituting the rotor core 12, that is, one end core sheet 22, which is provided at the end of the rotor core 12 on one axial side. The one end core sheet 22 is formed by punching so that the multiple protrusions 20 protrude radially outward from the one end core sheet 22, and the multiple protrusions 20 are formed by bending so that they protrude from the radially outward direction of the one end core sheet 22 to one axial side of the rotor core 12. Therefore, the multiple protrusions 20 can be easily provided on the end face on one axial side of the rotor core 12.

[0026] Similarly, the multiple protrusions 20 provided on the end face on the other axial side of the rotor core 12 are formed integrally with one of the multiple core sheets constituting the rotor core 12 that is provided at the end of the rotor core 12 on the other axial side (i.e., the other end core sheet 22). The other end core sheet 22 is formed by punching so that the multiple protrusions 20 protrude radially outward from the other end core sheet 22, and the multiple protrusions 20 are formed by bending so that they protrude from the radially outward direction of the other end core sheet 22 to the other axial side of the rotor core 12. Therefore, the multiple protrusions 20 can be easily provided on the end face on the other axial side of the rotor core 12.

[0027] Furthermore, in addition to the multiple protrusions 20 provided on the outer periphery of the end face on one axial side of rotor core 12, multiple protrusions 20 are also provided on the outer periphery of the end face on the other axial side of rotor core 12. Therefore, on both axial sides of rotor core 12, axial leakage magnetic flux from the stator can be guided between adjacent magnets 14 via protrusions 20. This makes it possible to more effectively increase reluctance torque.

[0028] In the above embodiment, as a preferred example, multiple protrusions 20 are provided on both axial end surfaces of the rotor core 12, but multiple protrusions 20 may also be provided on only one axial end surface of the rotor core 12.

[0029] 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.

[0030] Below, supplementary notes are provided regarding the technology of the present disclosure. (Appendix 1) A rotor core (12); Magnets (14) arranged in the circumferential direction of the rotor core and embedded in the rotor core; Equipped with A plurality of protrusions (20) are provided on the outer periphery of the axial end surface of the rotor core, the protrusions being located between adjacent magnets in the circumferential direction of the rotor core and protruding in the axial direction of the rotor core. Rotor (10). (Appendix 2) the rotor core is a laminate in which a plurality of core sheets are stacked in the axial direction of the rotor core, The plurality of protrusions are integrally formed on an end core sheet (22) that is a core sheet provided at an end of the rotor core in the axial direction among the plurality of core sheets, The end core sheet is formed by punching so that the plurality of protrusions protrude radially outward from the end core sheet, The plurality of protrusions are formed by bending the end core sheet from a state in which they protrude radially outward to a state in which they protrude in the axial direction of the rotor core. 10. The rotor of claim 1. (Appendix 3) a plurality of first protrusions as the plurality of protrusions are provided on an outer circumferential portion of an end surface on one axial side of the rotor core, A plurality of second protrusions are provided on an outer circumferential portion of an end surface on the other axial side of the rotor core, as the plurality of protrusions. 10. The rotor of claim 1 or 2. [Explanation of symbols]

[0031] 10... rotor, 12... rotor core, 12A... outer peripheral surface, 14... magnet, 14A... end of magnet 14 in the width direction, 16... insertion hole, 18... accommodation hole, 18A... outer surface, 18B... inner surface, 18C... lateral surface, 20... protrusion, 22... end core sheet, 24... recess, 26... flux barrier

Claims

1. A rotor core (12); Magnets (14) arranged in the circumferential direction of the rotor core and embedded in the rotor core; Equipped with A plurality of protrusions (20) are provided on the outer periphery of the axial end surface of the rotor core, the protrusions being located between adjacent magnets in the circumferential direction of the rotor core and protruding in the axial direction of the rotor core. Rotor (10).

2. the rotor core is a laminate in which a plurality of core sheets are stacked in the axial direction of the rotor core, The plurality of protrusions are integrally formed on an end core sheet (22) that is a core sheet provided at an end of the rotor core in the axial direction among the plurality of core sheets, The end core sheet is formed by punching so that the plurality of protrusions protrude radially outward from the end core sheet, The plurality of protrusions are formed by bending the end core sheet from a state in which they protrude radially outward to a state in which they protrude in the axial direction of the rotor core. The rotor of claim 1 .

3. a plurality of first protrusions as the plurality of protrusions are provided on an outer circumferential portion of an end surface on one axial side of the rotor core, a plurality of second protrusions as the plurality of protrusions are provided on an outer circumferential portion of an end surface on the other axial side of the rotor core; The rotor according to claim 1 or 2.

Images