Rotor

Abstract

To improve durability of a band for fixing a magnetic pole.SOLUTION: A rotor comprises: a rotor core; a plurality of magnetic poles disposed on an outer peripheral surface of the rotor core while being spaced in a circumferential direction of the rotor core; a band consisting of a fiber-reinforced composite material, the band being wound around the rotor core in such a manner that a fiber direction is along the circumferential direction and the band is in contact with outer peripheral side surfaces of the plurality of magnetic poles; and a binding member which is attached to the band within the space between the plurality of magnetic poles in the circumferential direction and binds the band in an axial direction of 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, multiple magnetic poles are fixed to the outer circumferential surface of a rotor core. The multiple magnetic poles are arranged at intervals in the circumferential direction of the rotor core. A band is wound around the rotor core so as to be in contact with the outer circumferential surface of each magnetic pole. Each magnetic pole is fixed to the rotor core by the band. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-51642 Summary of the Invention [Problem to be solved by the invention]

[0004] When the rotor rotates, centrifugal force acts on the band from each magnetic pole, and tension acts on the band along the circumferential direction. In order to improve the strength of the band in the circumferential direction, a fiber-reinforced composite material can be used as the band. In this case, the strength of the band in the circumferential direction can be improved by configuring the band so that the fiber direction of the fiber-reinforced composite material is along the circumferential direction of the rotor. However, although the strength of the fiber-reinforced composite material is high in the fiber direction, the strength in the direction perpendicular to the fiber direction is not so high. For this reason, when a fiber-reinforced composite material is used as the band as described above, there is a problem that the band is easily torn in the direction perpendicular to the circumferential direction, and the durability of the band is low. In this specification, a technology for improving the durability of the band is proposed. [Means for solving the problem]

[0005] The rotor comprises a rotor core, a plurality of magnetic poles arranged at intervals in the circumferential direction of the rotor core on the outer surface of the rotor core, a band made of fiber-reinforced composite material wound around the rotor core so that the fiber direction runs along the circumferential direction and contacts the outer surfaces of the magnetic poles, and a binding member attached to the band within the intervals between the magnetic poles in the circumferential direction and binding the band in the axial direction of the rotor core.

[0006] In this rotor, the band is bound in the axial direction of the rotor core by binding members provided in the spaces between the magnetic poles. This prevents the band from tearing in the axial direction (i.e., in the direction perpendicular to the circumferential direction). Therefore, this configuration can improve the durability of the band. [Brief description of the drawings]

[0007] [Figure 1] FIG. [Diagram 2] FIG. 4 is a plan view of the band 28 as viewed from the radially outer side. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The rotor 20 shown in Fig. 1 constitutes a part of an electric motor that drives the wheels of an electric vehicle. The rotor 20 is disposed inside a stator (not shown). The rotor 20 is disposed so as to be rotatable about a rotation axis AX.

[0009] The rotor 20 has a shaft 22 and a rotor core 24. The central axis of the shaft 22 coincides with the rotation axis AX. The rotor core 24 has a cylindrical shape. The shaft 22 is inserted into a central hole of the rotor core 24. The rotor core 24 is fixed concentrically to the shaft 22. The outer peripheral surface of the rotor core 24 has an octagonal cross-sectional shape.

[0010] The rotor 20 has a plurality of magnetic poles 26 (eight in this embodiment). Each magnetic pole 26 is, for example, a permanent magnet. The magnetic poles 26 are in contact with the outer peripheral surface of the rotor core 24. The magnetic poles 26 are arranged at intervals in the circumferential direction of the rotor core 24. Hereinafter, the intervals between the magnetic poles 26 in the circumferential direction are referred to as interval portions 27. The magnetic poles 26 are arranged rotationally symmetrical with respect to the rotation axis AX.

[0011] The rotor 20 has a band 28. The band 28 is wound around the rotor core 24 so as to be in contact with the outer peripheral surface 26a of each magnetic pole 26 (i.e., the surface of each magnetic pole 26 located on the radially outer side of the rotor 20). FIG. 2 shows the band 28 as seen from the radially outer side. In FIG. 2, the axial direction is a direction parallel to the rotation axis AX, and the circumferential direction is the rotation direction of the rotor 20. The band 28 is made of a fiber-reinforced composite material. That is, the band 28 is made of a material in which a fiber material is solidified by a base material (e.g., resin). For example, the band 28 is made of CFRP (Carbon Fiber Reinforced Plastics). Therefore, the band 28 contains a fiber material inside. The dashed line shown in FIG. 3 indicates the direction in which the fiber material contained in the band 28 extends (hereinafter, referred to as the fiber direction). As shown in FIG. 2, the band 28 is wound around the rotor core 24 with the fiber direction being the circumferential direction. Each magnetic pole 26 is fixed to the outer circumferential surface of the rotor core 24 by a band 28 .

[0012] As shown in FIG. 1, the rotor 20 has a plurality of binding members 30. Each binding member 30 is attached to the band 28 in the gap 27. As shown in FIG. 2, the binding member 30 has a shape that is longer in the axial direction (i.e., in the width direction of the band 28) than in the circumferential direction. The binding member 30 extends from one end of the band 28 to the other end in the axial direction. As shown in FIG. 1, the binding member 30 contacts both the inner peripheral surface and the outer peripheral surface of the band 28. The binding member 30 binds the band 28 by sandwiching the band 28 from the radial inside and the radial outside over the entire width direction of the band 28. The binding member 30 binds a plurality of fibers in the band 28 that are distributed in the width direction of the band 28. As shown in FIG. 1, at the position where the binding member 30 is provided, the band 28 is displaced radially inward (i.e., closer to the rotation axis AX) than the outer peripheral surface 26a of the magnetic pole 26. Therefore, the outer peripheral surface 30a of the binding member 30 is located radially inward of the outer peripheral surface 28a of the portion of the band 28 that covers the magnetic pole 26.

[0013] When the rotor 20 rotates, centrifugal force is applied to each magnetic pole 26. Even when centrifugal force is applied, the band 28 maintains each magnetic pole 26 in a fixed state. In addition, when centrifugal force is applied, a force is applied from each magnetic pole 26 to the band 28 in a radially outward direction. As a result, a tensile load is applied to the band 28 along the circumferential direction. Since the band 28 has high strength against a tensile load in the circumferential direction (i.e., the fiber direction), the band 28 is prevented from breaking in the circumferential direction. In addition, when a load is repeatedly applied to the band 28, the fibers are likely to separate in a direction perpendicular to the fiber direction (i.e., the axial direction). However, in this embodiment, the binding member 30 restrains the band 28 in the axial direction, so that the strength of the band 28 in the axial direction is improved. In other words, fiber separation is unlikely to occur in the axial direction, and the durability of the band 28 is high. Therefore, the rotor 20 can be used in a higher load environment (for example, an environment in which the band 28 rotates at a high speed). Additionally, the use of bands 28 allows rotor 20 to be made smaller in size compared to other high strength rotor structures.

[0014] In addition, in this embodiment, since the band 28 is displaced radially inward at the gap 27, the outer peripheral surface 30a of the binding member 30 is located radially inward of the outer peripheral surface 28a of the band 28. In other words, the binding member 30 does not protrude from the outer peripheral surface of the rotor 20. This makes it possible to reduce the air gap between the rotor 20 and the stator, enabling the electric motor to output high torque.

[0015] 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]

[0016] 20: Rotor 22: Shaft 24: Rotor core 26 :Magnetic pole 28: Band 30: Binding material

Claims

[Claim 1] A rotor, A rotor core; a plurality of magnetic poles arranged at intervals in a circumferential direction of the rotor core on an outer circumferential surface of the rotor core; a band made of a fiber-reinforced composite material, the band being wound around the rotor core so that the fiber direction is along the circumferential direction and the band is in contact with the outer peripheral surfaces of the magnetic poles; a binding member attached to the band within an interval between the plurality of magnetic poles in the circumferential direction and binding the band in the axial direction of the rotor core; A rotor having

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