Stator for electric rotating machine

1. A stator for an electric rotating machine, the stator comprising:

an annular stator core comprised of a plurality of stator core segments that are arranged in a circumferential direction of the stator core to adjoin one another in the circumferential direction;

an outer ring that is fitted on radially outer surfaces of the stator core segments so as to fasten the stator core segments together; and

a stator coil mounted on the stator core,

wherein

each of the stator core segments is formed of a plurality of stator core sheets that are laminated in an axial direction of the stator core,

each of the stator core sheets has a pair of major surfaces perpendicular to the axial direction of the stator core and a reinforcement portion that includes a recess formed in one of the major surfaces of the stator core sheet and a protrusion formed on the other major surface,

the stator core sheets are laminated so that for each adjoining pair of the stator core sheets, the protrusion of one of the stator core sheets is fitted in the recess of the other stator core sheet, and

a clearance is provided between each facing pair of side surfaces of the recesses and protrusions of the stator core sheets.

2. The stator as set forth in claim 1 , wherein the stator core has a plurality of slots that are formed in a radially inner surface of the stator core so as to be spaced from one another in the circumferential direction of the stator core, and

each of the reinforcement portions of the stator core sheets is positioned radially outside the slots of the stator core and extends along the circumferential direction of the stator core.

3. The stator as set forth in claim 1 , wherein the stator core has a plurality of slots that are formed in a radially inner surface of the stator core so as to be spaced from one another in the circumferential direction of the stator core,

the reinforcement portions of the stator core sheets are positioned radially outside the slots of the stator core, and

for each of the stator core sheets, the reinforcement portion of the stator core sheet is formed to extend straight in a direction perpendicular to an imaginary plane that bisects the stator core sheet in the circumferential direction of the stator core.

4. The stator as set forth in claim 1 , wherein for each of the stator core sheets, the reinforcement portion of the stator core sheet is provided in a plurality of places in the stator core sheet.

5. The stator as set forth in claim 1 , wherein each of the stator core sheets includes an insulating layer that is provided on at least one of the major surfaces of the stator core sheet, and

for each adjoining pair of the stator core sheets, the protrusion of one of the stator core sheets is fitted in the recess of the other stator core sheet without a gap between a top surface of the protrusion and a bottom surface of the recess.

6. The stator as set forth in claim 1 , wherein each of the stator core sheets further has a lock portion that includes a recess formed in one of the major surfaces of the stator core sheet and a protrusion formed on the other major surface, and

for each adjoining pair of the stator core sheets, the protrusion of the lock portion of one of the stator core sheets is fitted in the recess of the lock portion of the other stator core sheet, thereby locking the stator core sheets together.

7. The stator as set forth in claim 1 , wherein each of the stator core sheets is made of magnetic steel.