Rotating electric machine and method for manufacturing rotor
A rotor constituting a rotating electric machine includes a rotating shaft and a permanent magnet. A sleeve covering the outer surface of the permanent magnet is attached to the rotating shaft. A resin coating layer is formed on an outer circumferential wall of the sleeve. The resin coating layer includes a base portion and a plurality of ridges formed on the outer circumferential wall of the base portion. A riblet recessed relative to the plurality of ridges is formed between the plurality of ridges.
1 . A method of manufacturing a rotor that includes a rotating shaft and a permanent magnet held on the rotating shaft and is surrounded by a stator in a rotating electric machine, the method comprising:
covering an outer surface of the permanent magnet with a sleeve made of a carbon fiber reinforced polymer to attach the sleeve;
coating an outer circumferential wall of the sleeve with a resin coating layer; and
forming, in the resin coating layer, a base portion constituted by a cylindrical body covering the outer circumferential wall of the sleeve and a ridge structure protruding from an outer circumferential wall of the base portion, by processing and removing a part of an outer circumferential wall of the resin coating layer,
wherein in the forming of the base portion and the ridge structure, by machining and removing the part of the outer circumferential wall of the resin coating layer the ridge structure is provided as one or a plurality of convex portions forming a plurality of ridges that extend in parallel to each other, thereby forming a riblet recessed relative to the plurality of ridges, and
wherein a sum of a thickness of the base portion formed by machining the resin coating layer and a thickness of each of the plurality of ridges is smaller than a pre-machining thickness of the resin coating layer.
2 . The method of manufacturing the rotor according to claim 1 , wherein in the forming of the base portion and the ridge structure, the plurality of ridges are formed so as to extend in a direction intersecting an axial direction of the rotating shaft at an angle of 45° to 90°.
3 . The method of manufacturing the rotor according to claim 1 , wherein when a height of each of the plurality of ridges is H and a pitch between two adjacent ridges among the plurality of ridges is S, the plurality of ridges are formed so as to satisfy a following equation in the forming of the base portion and the ridge structure:
H=0.5S.
4 . The method of manufacturing the rotor according to claim 1 , wherein when the plurality of ridges are cut in a direction orthogonal to an extending direction of the plurality of ridges, the plurality of ridges are formed in the forming of the base portion and the ridge structure, in a manner so that a cross-sectional shape of each of the plurality of ridges is a triangle.
5 . The method of manufacturing the rotor according to claim 4 , wherein when the plurality of ridges are cut in the direction orthogonal to the extending direction of the plurality of ridges, the plurality of ridges are formed in the forming of the base portion and the ridge structure, in a manner so that a top portion in a cross section of each of the ridges has an angle of 30° to 90°, the top portion protruding most outward in a diametrical direction of the rotating shaft.
6 . The method of manufacturing the rotor according to claim 1 , wherein the coating with the resin coating layer is performed to form the resin coating layer by using, as a base material resin of the resin coating layer, a resin that causes less wear of a cutting tool when machining is performed on the base material resin compared to wear of the cutting tool when machining is performed on the carbon fiber reinforced polymer under a same machining condition.
7 . The method of manufacturing the rotor according to claim 6 , wherein an epoxy-based resin or a paraxylene-based resin is used as the base material resin.
8 . The method of manufacturing the rotor according to claim 1 , wherein in the forming of the base portion and the ridge structure, a cutting tool having a shape that is capable of forming the base portion and the plurality of ridges is provided.