Stator assembly of hairpin winding motor and manufacturing method thereof

A stator assembly of a hairpin winding motor comprising:

• a plurality of hairpin coils continuously connected along a circumferential direction to form a coil winding;
• and
• a stator core configured to fix the hairpin coils,
• wherein:
• outer circumferential surfaces of the hairpin coils formed in the circumferential direction contact an inner circumferential surface of the stator core;
• each of the hairpin coils includes a head portion exposed to the outside of the stator core in an axial direction, and leg portions extending from one end and the other end of the head portion and configured to be inserted into a core slot of the stator core;
• the leg portions have a shape which is repeated in the circumferential direction by one pole pitch to be continuously connected;
• a cross-section of each leg portion has a trapezoidal shape of which the outside is wider than the inside, such that a width thereof decreases in a direction toward an inner diameter from an outer diameter of the stator core;
• the stator core includes a ring core formed in a cylindrical shape and in which the hairpin coils are disposed, and a plurality of pin cores are inserted into the ring core to fix the hairpin coils to the ring core;
• the ring core includes:
• a yoke formed of a magnetic material to form a magnetic path;
• a plurality of assembly parts protruding from an inner circumferential surface of the yoke in a radial direction;
• and
• core slots formed between the plurality of assembly parts;
• the plurality of pin cores include:
• a plurality of insertion parts at first ends of the pin cores, which are inserted into the core slots;
• teeth connected to the plurality of insertion parts and inserted between the leg portions of the hairpin coils;
• and
• shoes extending in both directions of second ends of the pin cores opposite the first ends of the pin cores to connect the plurality of insertion parts;
• each insertion part has a rectangular cross-sectional shape and includes;
• bent portions formed to face each other at positions spaced apart from an end of each insertion part which is inserted into the core slot;
• some, but not all, of the insertion parts further include a tab portion formed at the second end, the tab portion having a shape inclined from a side surface of the connected tooth;
• and
• each of the bent portions has a smooth, curved shape.