Stator of rotating electric machine and manufacturing method of the stator

1. A stator of a rotating electric machine, said stator comprising:

a stator core including a cylinder-shaped back yoke, a plurality of teeth extending radially inward from inside the back yoke and a plurality of slots each formed between any two adjacent teeth; and

a plurality of coils fitted in the slots such that the individual teeth are concentratedly wound by the coils;

wherein the individual coils are pre-formed coil units having a common shape, each of the coil units being made by winding a conductor in a generally rectangular form, stacking one conductor line on top of another in a single row, and each of the coil units having two parallel straight portions inserted into the slots on both sides of each tooth; and

wherein the two parallel straight portions of the conductor of each coil unit are fitted in two adjacent slots in such a way that one straight portion of the conductor is laid in an inner layer in one of the two adjacent slots and the other straight portion of the conductor is laid in an outer layer in the other of the two adjacent slots so that individual conductor lines fitted in each slot are radially stacked one on top of another in a single row as viewed in cross section.

2. The stator of the rotating electric machine according to claim 1 , wherein the conductor has flat surfaces so that multiple layers of conductor lines are stacked one on top of another with the flat surfaces of the conductor lines placed face to face with each other.

3. The stator of the rotating electric machine according to claim 1 , wherein both outgoing ends of each coil unit are taken out of two adjacent slots at one axial end of the stator core.

4. The stator of the rotating electric machine according to claim 3 , wherein one outgoing end of each coil unit is taken out from an innermost layer in one of the two adjacent slots whereas the other outgoing end of the same coil unit is taken out from an outermost layer in the other one of the two adjacent slots.

5. The stator of the rotating electric machine according to claim 3 , wherein both outgoing ends of each coil unit are taken out from about the middle of inner and outer layers of each successive slot.

6. The stator of the rotating electric machine according to claim 1 , wherein both outgoing ends of each coil unit are taken out of each successive slot from opposite axial ends of the stator core.

7. The stator of the rotating electric machine according to claim 1 , wherein the stator core is cut at least along one axial line, forming facing cut surfaces on both cut ends of the stator core, and the facing cut surfaces are joined to each other.

8. The stator of the rotating electric machine according to claim 7 , wherein the facing cut surfaces are formed in one of the teeth.

9. The stator of the rotating electric machine according to claim 7 , wherein the facing cut surfaces are formed at the bottom of one of the slots.

10. The stator of the rotating electric machine according to claim 7 , wherein one of the facing cut surfaces is formed on one side of the back yoke extending sideways from a basal part of one tooth while the other cut surface is formed on the opposite side of the back yoke at a basal part of the adjacent tooth.