Stator for rotary electric machine
A stator includes: a stator core that is shaped in a tubular form and has a plurality of slots; and a plurality of conductor segments that are inserted into the slots and are electrically connected with each other to form a stator coil. Each conductor segment has: an electrical conductor that is shaped in a linear form; an electrical insulation film that covers a periphery of the electrical conductor; a plurality of capsules that are hollow and are dispersed inside the electrical insulation film; and a bend that forms a bent-back shape on the conductor segment at an end portion of the stator core which faces in an axial direction. Among the plurality of capsules, capsules located at an outer periphery of the bend and capsules located at an inner periphery of the bend are respectively shaped in an ellipsoid form at each of the plurality of conductor segments.
1 . A stator for a rotary electric machine, comprising:
a stator core that is shaped in a tubular form and has a plurality of slots; and
a plurality of conductor segments that are inserted into the plurality of slots and are electrically connected with each other to form a stator coil, wherein:
each of the plurality of conductor segments has:
an electrical conductor that is shaped in a linear form;
an electrical insulation film that covers a periphery of the electrical conductor;
a plurality of capsules that are hollow and are dispersed inside the electrical insulation film; and
a bend that forms a bent-back shape on the conductor segment at an end portion of the stator core which faces in an axial direction; and
among the plurality of capsules, capsules located at an outer periphery of the bend and capsules located at an inner periphery of the bend are respectively shaped in an ellipsoid form at each of the plurality of conductor segments.
2 . The stator according to claim 1 , wherein at each of the plurality of conductor segments, a major-diameter direction of each of the capsules located at the outer periphery of the bend is along a circumferential direction of the outer periphery of the bend.
3 . The stator according to claim 1 , wherein at each of the plurality of conductor segments, a major-diameter direction of each of the capsules located at the inner periphery of the bend is along a direction perpendicular to a circumferential direction of the outer periphery of the bend.
4 . The stator according to claim 1 , wherein at each of the plurality of conductor segments, a volume of each of the capsules located at the inner periphery of the bend is smaller than a volume of each of the capsules located at the outer periphery of the bend.
5 . The stator according to claim 1 , wherein:
the electrical insulation film is made of polyimide at each of the plurality of conductor segments;
each of the plurality of conductor segments is fixed to the stator core by varnish at an inside of a corresponding one of the plurality of slots; and
among the plurality of capsules, capsules placed at a surface of the electrical insulation film are covered by the polyimide at each of the plurality of conductor segments.
6 . The stator according to claim 1 , wherein:
the electrical insulation film is made of polyimide at each of the plurality of conductor segments;
each of the plurality of conductor segments has an exposed portion of the electrical conductor, which is exposed from the electrical insulation film at an end portion of each of the plurality of conductor segments, and the exposed portions of each corresponding two of the plurality of conductor segments are welded together to form a welded portion;
the welded portion and an adjacent portion of the electrical insulation film, which is placed adjacent to the welded portion at each corresponding two of the plurality of conductor segments, are powder-coated; and
among the plurality of capsules, capsules placed at a surface of the electrical insulation film are covered by the polyimide at each of the plurality of conductor segments.
7 . The stator according to claim 1 , wherein:
one inserting portion of each of adjacent two of the plurality of conductor segments, which are placed adjacent to each other, is inserted into a common slot among the plurality of slots, and another inserting portion of one of the adjacent two of the plurality of conductor segments and another inserting portion of another one of the adjacent two of the plurality of conductor segments are inserted into two different slots, respectively, among the plurality of slots;
each of the plurality of conductor segments has an apex portion, which is bent separately from the bend;
a radius of curvature of the inner periphery of the bend is equal to or smaller than 3.5 mm; and
a radius of curvature of an inner periphery of the apex portion is equal to or smaller than 2.0 mm.
8 . The stator according to claim 1 , wherein each of the plurality of conductor segments has a bent portion that is bent separately from the bend, and an outer periphery of the bent portion of each of the plurality of conductor segments is out of contact with and is spaced from an adjacent one of the plurality of conductor segments, which is placed adjacent to the outer periphery of the bent portion, by a distance that is longer than one half of a thickness of the electrical conductor of each of the plurality of conductor segments.