Stator manufacturing method and stator

1. A stator manufacturing method comprising:

a step of forming a stator core by stacking a plurality of electrical steel sheets;

a step of mounting a coil in slots of the stator core; and

a step of forming a skew having a curved shape such that the plurality of electrical steel sheets structuring the stator core are gradually displaced in a circumferential direction, by pressing, after the coil is mounted in the slots of the stator core, a skew-forming mechanism portion provided on an outer circumferential surface or an inner circumferential surface of the stator core with a skew-forming jig, wherein

the slots formed by gradually displacing the plurality of electrical steels sheets by forming the skew are formed such that adjacent side walls of the slots have smooth curved surfaces along a axial direction and an amount of displacement of electrical steel sheets of the plurality of electrical steel sheets at both axial ends of the stator core is smaller than an amount of displacement of electrical steels sheets of the plurality of electrical steel sheets at an axial center of the stator core,

one of the skew-forming mechanism portion and the skew-forming jig has a curved shape to correspond to the curved shape of the skew.

2. The stator manufacturing method according to claim 1 , wherein

the step of forming the skew is a step of forming the skew having the curved shape that changes smoothly when viewed in a radial direction of the stator core.

3. The stator manufacturing method according to claim 1 , wherein

the skew-forming mechanism portion provided on the outer circumferential surface or the inner circumferential surface of the stator core includes a protrusion portion or a groove portion formed to extend along an axial direction, the skew-forming jig has the curved shape corresponding to the curved shape of the skew to press the protrusion portion or the groove portion along the circumferential direction, and

the step of forming the skew is a step of forming the skew having the curved shape by pressing the skew-forming mechanism portion, including the protrusion portion or the groove portion, along the circumferential direction with the skew-forming jig having the curved shape corresponding to the curved shape of the skew so that the plurality of electrical steel sheets structuring the stator core are gradually displaced in the circumferential direction.

4. The stator manufacturing method according to claim 3 , wherein

the skew-forming jig includes a first skew-forming jig and a second skew-forming jig, the first skew-forming jig having a curved shape that projects in the circumferential direction to correspond to the curved shape of the skew, the second skew-forming jig having a curved shape that is recessed in the circumferential direction to correspond to the curved shape of the skew, and

the step of forming the skew is a step of forming the skew having the curved shape by pressing the skew-forming mechanism portion, including the protrusion portion or the groove portion, with the first skew-forming jig and the second skew-forming jig, while sandwiching the skew-forming mechanism portion between the first skew-forming jig and the second skew-forming jig, so that the plurality of electrical steel sheets structuring the stator core are gradually displaced from each other in the circumferential direction.

5. The stator manufacturing method according to claim 1 , wherein

the skew-forming mechanism portion provided on the outer circumferential surface or the inner circumferential surface of the stator core includes a hole portion or a groove portion that has a curved shape corresponding to the curved shape of the skew,

the skew-forming jig has a linear, rod-like shape to be inserted in the hole portion or the groove portion, and

the step of forming the skew is a step of forming the skew having the curved shape by inserting the skew-forming jig having the linear, rod-like shape into the skew-forming mechanism portion, including the hole portion or the groove portion, along an axial direction so that the plurality of electrical steel sheets structuring the stator core are gradually displaced in the circumferential direction.

6. The stator manufacturing method according to claim 1 , wherein

a plurality of the skew-forming mechanism portions are provided,

a plurality of the skew-forming jigs are provided to correspond to the plurality of the skew-forming mechanism portions, and

the step of forming the skew is a step of forming the skew having the curved shape by simultaneously pressing, after the coil is mounted in the slots of the stator core, the plurality of the skew-forming mechanism portions provided on the outer circumferential surface or the inner circumferential surface of the stator core with the plurality of the skew-forming jigs so that the plurality of electrical steel sheets structuring the stator core are gradually displaced in the circumferential direction.

7. The stator manufacturing method according to claim 1 , wherein

the step of forming the stator core is a step of forming the slots in a linear shape by stacking the plurality of electrical steel sheets, and

the step of forming the skew is a step of forming the skew having the curved shape to the slots.

8. The stator manufacturing method according to claim 7 , wherein

the step of forming the skew includes a step of forming slot-held portions of the coil that have a linear shape and that are held in the slots that is linear before formation of the skew, into a shape corresponding to a shape of the slots that are deformed into a curved shape after formation of the skew.

9. The stator manufacturing method according to claim 7 , wherein

the step of forming the stator core is a step of forming the skew-forming mechanism portion in a linear shape by stacking the plurality of electrical steel sheets, and

the step of forming the skew includes a step of forming the skew-forming mechanism portion that is linear before formation of the skew, into a shape identical to a shape of the slots that are deformed into a curved shape after formation of the skew.

10. A stator comprising:

a stator core including a stack of a plurality of electrical steel sheets; and

a coil mounted in slots of the stator core, wherein

the slots formed in the stator core have a skew shape that or curved such that the plurality of electrical steel sheets are gradually displaced in a circumferential direction,

the slots formed by gradually displacing the plurality of electrical steels sheets by forming the skew shape are formed such that adjacent side walls of the slots have smooth curved surfaces along the axial direction and an amount of displacement of electrical steel sheets of the plurality of electrical steel sheets at both axial ends of the stator core is smaller than an amount of displacement of electrical steels sheets of the plurality of electrical steel sheets at an axial center of the stator core, and

an outer circumferential surface or an inner circumferential surface of the stator core is provided with a skew-forming mechanism portion that has a curved shape corresponding to the skew shape before the plurality of electrical steel sheets are displaced from each other in the circumferential direction.