Rotor

Abstract

To reduce an impact applied to a magnet.SOLUTION: A rotor comprises: a rotor core; a magnet which comes into contact with an outer peripheral surface of the rotor core; and a surrounding member which surrounds the magnet and the rotor core from an outer peripheral side of the rotor core so as to fix the magnet to the rotor core. The rotor core has: a slit which extends along the outer peripheral surface of the rotor core; a main part which is located further on a center axis side of the rotor core than the slit; an outer peripheral part which is located further on the outer peripheral side of the rotor core than the slit; and a connection part which connects the main part to the outer peripheral part. When viewed along the radial direction of the rotor core, the slit is disposed at a position overlapping the magnet.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a rotor.

[0002] The rotor disclosed in Patent Document 1 includes a rotor core, a magnet, and a surrounding member. The surrounding member surrounds the magnet and the rotor core, thereby fixing the magnet to the rotor core. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-205725 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the rotor of Patent Document 1 rotates at high speed, a high centrifugal force is applied to the magnet. Then, the surrounding member is pushed by the magnet and deformed toward the outer periphery. On the other hand, since the rotor core has high rigidity, the rotor core hardly deforms at all. As a result, a gap is formed between the magnet and the rotor core. When a gap is formed between the magnet and the rotor core, the magnet collides with the rotor core when the centrifugal force decreases thereafter, and an impact is applied to the magnet. This specification proposes a technology for reducing the impact applied to the magnet. [Means for solving the problem]

[0005] The rotor disclosed in this specification has a rotor core, a magnet in contact with the outer peripheral surface of the rotor core, and a surrounding member that surrounds the magnet and the rotor core from the outer peripheral side of the rotor core to fix the magnet to the rotor core. The rotor core has slits extending along the outer peripheral surface of the rotor core, a main part located closer to the central axis of the rotor core than the slits, an outer peripheral part located closer to the outer peripheral side of the rotor core than the slits, and a connecting part that connects the main part and the outer peripheral part. The slits are arranged in a position that overlaps with the magnet when viewed along the radial direction of the rotor core.

[0006] In this rotor, a portion of the outer periphery forms a beam portion that faces the main portion via a slit. When a high centrifugal force is applied to the magnet, the magnet is displaced toward the outer periphery and the beam portion deforms toward the outer periphery in response. This prevents gaps from being generated between the magnet and the beam portion (i.e., the rotor core). Therefore, the magnet is less likely to be subjected to impact when the centrifugal force decreases. This rotor structure therefore improves the durability of the magnet. [Brief description of the drawings]

[0007] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Fig. 1 shows a rotor 10 according to an embodiment. The dashed lines in Fig. 1 indicate the boundaries of the magnetic pole range of the rotor 10. Although not shown, a stator is disposed around the rotor 10. The rotor 10 and the stator constitute an electric motor.

[0009] The rotor 10 has a shaft 20, a rotor core 30, a plurality of magnets 40, and a surrounding member 50. The shaft 20 is supported rotatably around its central axis AX. The rotor core 30 has a cylindrical shape. The shaft 20 is inserted into a central hole of the rotor core 30. The rotor core 30 is fixed to the shaft 20. Within one magnetic pole range, the outer peripheral surface 32 of the rotor core 30 is a flat surface. Therefore, the outer peripheral surface 32 of the rotor core 30 has a polygonal cross-sectional shape as a whole. The plurality of magnets 40 are arranged on the outer peripheral surface 32 of the rotor core 30. One magnet 40 is arranged in each magnetic pole range. Each magnet 40 is in contact with the outer peripheral surface 32 of the rotor core 30. The surrounding member 50 has a cylindrical shape. The surrounding member 50 surrounds the plurality of magnets 40 and the rotor core 30 from the outer periphery. Each magnet 40 is sandwiched between the inner circumferential surface 52 of the surrounding member 50 and the outer circumferential surface 32 of the rotor core 30. In this way, each magnet 40 is fixed to the rotor core 30.

[0010] The rotor core 30 is provided with a plurality of slits 30c. Each slit 30c is provided in each magnetic pole range. The slits 30c extend from both ends of the magnetic pole range toward the center of the magnetic pole range along the outer circumferential surface 32. Each slit 30c is provided at a position overlapping with the magnet 40 when viewed along the radial direction of the rotor core 30. No slit 30c is provided in the center of the magnetic pole range. In the following, a portion of the rotor core 30 where no slit 30c is provided (i.e., a portion between two slits 30c) is referred to as a connection portion 30d. In the following, a portion closer to the center than the slits 30c (i.e., a portion closer to the central axis AX) is referred to as a main portion 30a. In the following, a portion of the rotor core 30 on the outer circumferential side than the slits 30c is referred to as an outer circumferential portion 30b. The outer circumferential portion 30b includes the outer circumferential surface 32. The outer circumferential portion 30b is connected to the main portion 30a by the connection portion 30d. The outer peripheral portion 30b has a beam portion 34 extending in the circumferential direction from the connection portion 30d along the outer peripheral surface 32. The beam portion 34 faces the main portion 30a via the slit 30c. Since the beam portion 34 is thin, the beam portion 34 has flexibility.

[0011] When the rotor 10 rotates at high speed around the central axis AX, a high centrifugal force is applied to the magnet 40. Then, the surrounding member 50 is pushed by the magnet 40 and deformed toward the outer periphery, and the magnet 40 is displaced toward the outer periphery. When a high centrifugal force is applied to the magnet 40, a high centrifugal force is also applied to the beam portion 34. In addition, the beam portion 34 has flexibility. Therefore, when the magnet 40 is displaced toward the outer periphery, the beam portion 34 bends toward the outer periphery following the displacement of the magnet 40. This suppresses the occurrence of a gap between the magnet 40 and the outer periphery surface 32 of the rotor core 30. Therefore, when the centrifugal force applied to the magnet 40 subsequently decreases, the magnet 40 is less likely to be subjected to an impact. Therefore, according to the structure of the rotor 10 of the embodiment, the durability of the magnet 40 can be improved.

[0012] As shown in Fig. 2, the slit 30c may be provided in a range including the center of the magnetic pole range, and the connection portion 30d may be provided at the end of the magnetic pole range. In this case, as shown in Fig. 2(a), a notch portion 34x that separates the beam portion 34 into two may be provided in the center of the magnetic pole range, or as shown in Fig. 2(b), the notch portion 34x may not be provided.

[0013] As shown in FIG. 3, a magnetic core 60 may be provided on the outer periphery of the magnet 40 (that is, between the magnet 40 and the surrounding member 50).

[0014] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or drawings achieves multiple objectives simultaneously, and achieving one of the objectives itself has technical utility. [Explanation of symbols]

[0015] 10: Rotor 20: Shaft 30: Rotor core 30c: Slit 30d: Connection 40: Magnet 50: Enclosing member

Claims

[Claim 1] A rotor core; A magnet in contact with an outer peripheral surface of the rotor core; a surrounding member that surrounds the magnet and the rotor core from the outer circumferential side of the rotor core to fix the magnet to the rotor core; having The rotor core is A slit extending along the outer circumferential surface of the rotor core; a main portion located closer to a central axis of the rotor core than the slit; an outer circumferential portion located on an outer circumferential side of the rotor core relative to the slits; a connection portion that connects the main portion and the outer circumferential portion; having A rotor, wherein the slits are arranged at positions overlapping with the magnets when viewed along the radial direction of the rotor core.

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