Rotor

Abstract

To easily fix a magnet to a rotor core.SOLUTION: A rotor includes a rotor core, a shaft, and a plurality of magnets. The rotor core includes a center hole and a plurality of magnet housing holes disposed around the center hole. The shaft is disposed in the center hole of the rotor core, and is fixed to the rotor core in a state where pressure is applied from the shaft to the rotor core. Each magnet is disposed in the corresponding magnet housing hole, and being fixed to the rotor core by pressure applied from the shaft to the rotor core.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In the rotor disclosed in Patent Document 1, magnets are fixed in magnet accommodating holes provided in a rotor core. In the staking process for fixing the magnets, with the magnets accommodated in the magnet accommodating holes, pressure is applied from both axial sides to the part of the rotor core that is inside the magnet accommodating holes. This causes the inner surface of the magnet accommodating holes to deform toward the magnets, and the magnets are crimped and fixed in place. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-003748 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology of Patent Document 1, the staking process for fixing the magnets to the rotor core is complicated. This specification proposes a rotor structure that makes it possible to easily fix the magnets to the rotor core. [Means for solving the problem]

[0005] The rotor disclosed in this specification has a rotor core, a shaft, and a plurality of magnets. The rotor core has a central hole and a plurality of magnet accommodating holes arranged around the central hole. The shaft is arranged in the central hole of the rotor core and is fixed to the rotor core with pressure being applied from the shaft to the rotor core. Each of the magnets is arranged in a corresponding one of the magnet accommodating holes and is fixed to the rotor core by the pressure applied from the shaft to the rotor core.

[0006] In the manufacturing process of this rotor, when the shaft is fixed into the central hole with the magnets housed in the magnet housing holes, the magnets are fixed in place by the pressure applied from the shaft to the rotor core. Since the shaft and magnets can be fixed to the rotor core in a common process, the magnets can be easily fixed to the rotor core. [Brief description of the drawings]

[0007] [Figure 1] FIG. [Diagram 2] FIG. 4 is a side view of the rotor core before the shaft is attached. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Fig. 1 is a side view of a rotor 10 viewed in a direction parallel to a rotation axis AX (hereinafter referred to as the axial direction). The rotor 10 is a part of an electric motor and is housed inside a stator (not shown). As shown in Fig. 1, the rotor 10 has a rotor core 20, a shaft 30, and a plurality of magnets 40. Note that in Fig. 1, the shaft 30 and the magnets 40 are shown by hatching for ease of viewing.

[0009] The rotor core 20 is formed of a laminate in which a plurality of electromagnetic steel plates are stacked in the axial direction. The rotor core 20 has a cylindrical shape. A central hole 22 extending along the rotation axis AX is provided in the center of the rotor core 20. The central hole 22 penetrates the rotor core 20 in the axial direction. A plurality of magnet accommodating holes 24 are provided around the central hole 22. The magnet accommodating holes 24 are arranged at regular angular intervals around the central hole 22. Each magnet accommodating hole 24 penetrates the rotor core 20 in the axial direction. Each magnet accommodating hole 24 has a rectangular cross-sectional shape.

[0010] The shaft 30 is inserted into the central hole 22 of the rotor core 20. The shaft 30 is fixed to the rotor core 20 within the central hole 22. As will be described later, the shaft 30 is press-fitted into the central hole 22. Therefore, pressure is applied from the shaft 30 to the rotor core 20.

[0011] Each magnet 40 has the shape of a rectangular prism that is long in the axial direction, and is inserted into the corresponding magnet accommodating hole 24. Each magnet 40 is fixed to the rotor core 20 within the magnet accommodating hole 24.

[0012] Next, a manufacturing process of the rotor 10 will be described. Fig. 2 shows the rotor core 20 before the shaft 30 and the magnets 40 are fixed. Before the shaft 30 is attached, a plurality of protrusions 22a are present on the inner surface of the central hole 22. The protrusions 22a are arranged at regular angular intervals in the circumferential direction. Therefore, the diameter R20x of the central hole 22 at a position where the protrusion 22a is present is smaller than the diameter R20y of the central hole 22 at a position where the protrusion 22a is not present. The shape of the central hole 22 can be formed by press molding or the like.

[0013] In the manufacturing process of the rotor 10, first, the magnets 40 are placed in each magnet accommodating hole 24. Next, as shown in FIG. 1, the shaft 30 is inserted into the center hole 22. The diameter R30 (see FIG. 1) of the shaft 30 is larger than the diameter 20x of the center hole 22 at the position where the protrusion 22a is present, and is slightly smaller than the diameter R20y of the center hole 22 at the position where the protrusion 22a is not present. Therefore, when the shaft 30 is inserted into the center hole 22, each protrusion 22a is pressed and crushed by the shaft 30. That is, the shaft 30 is press-fitted into the center hole 22. In this way, the shaft 30 is fixed in the center hole 22 by the press-fitting. Also, when each protrusion 22a is crushed by the shaft 30, the rotor core 20 is slightly deformed toward the outer periphery as shown by the arrow 100 in FIG. 2. As a result, the surface 24a on the inner periphery side of each magnet accommodating hole 24 is deformed into a convex shape as shown by the dashed line 102 in FIG. 2. 2 shows an exaggerated view of the deformation of surface 24a, and in reality, the amount of deformation of surface 24a is small. When surface 24a on the inner periphery of magnet accommodating hole 24 is deformed into a convex shape, magnet 40 is sandwiched and fixed within magnet accommodating hole 24. In this way, when shaft 30 is press-fitted into central hole 22, each magnet 40 is fixed to rotor core 20 together with shaft 30. In this way, rotor 10 in FIG. 1 is completed.

[0014] As described above, in the manufacturing process of the embodiment, each magnet 40 can be fixed to the rotor core 20 simply by press-fitting the shaft 30 into the central hole 22. The structure of the rotor 10 allows each magnet 40 to be easily fixed to the rotor core 20. Also, since a dedicated process for fixing the rotor core 20 is not required, the rotor 10 can be manufactured efficiently.

[0015] Furthermore, the structure of the rotor 10 eliminates the need for members (such as nuts) for fixing the shaft 30 to the rotor core 20, and eliminates the need for members (such as adhesives, foaming agents, etc.) for fixing the magnets 40 to the rotor core 20. This technology makes it possible to simplify the rotor structure compared to conventional techniques.

[0016] In the above-described embodiment, the shaft 30 is fixed to the rotor core 20 by press fitting. However, the shaft 30 may be fixed to the rotor core 20 by another fixing structure as long as the fixing structure allows pressure to be applied from the shaft 30 to the rotor core 20. For example, the shaft 30 may be fixed in the central hole 22 by shrink fitting.

[0017] 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]

[0018] 10: Rotor 20: Rotor core 22: Center hole 22a: Convex part 24: Magnet receiving hole 30: Shaft 40: Magnet

Claims

[Claim 1] A rotor having a rotor core, a shaft, and a plurality of magnets, The rotor core has a central hole and a plurality of magnet accommodating holes arranged around the central hole, the shaft is disposed in a central hole of the rotor core and is fixed to the rotor core in a state in which pressure is applied to the rotor core from the shaft, Each of the magnets is disposed in the corresponding magnet accommodating hole and is fixed to the rotor core by the pressure applied to the rotor core from the shaft. Rotor.

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