Rotary electric machine and manufacturing method therefor

1. A rotary electric machine comprising:

a floored cylindrical case in which an opening at a first end of a cylindrical portion is closed by a floor portion;

a stator that comprises:

an annular stator core that is held inside said case by being fitted together with and fixed to said cylindrical portion; and

coils that are mounted to said stator core;

a frame that closes an opening at a second end of said cylindrical portion;

a rotating shaft that is rotatably held by said floor portion and said frame, and that is disposed so as to be coaxial to said stator; and

a rotor that is fixed to said rotating shaft, and that is disposed on an inner circumferential side of said stator,

wherein:

a first stress relieving indented portion, forming a groove on an inner circumferential surface of said cylindrical portion, is formed above said floor portion and around an entire circumference at a first end of said inner circumferential surface of said cylindrical portion such that a gap is formed between a first end portion of an outer circumferential surface of said stator core and said the first stress relieving indented portion, and a thickness of a portion of the cylindrical portion including the first stress relieving indented portion is thinner than a thickness of remaining portion of the cylindrical portion.

2. The rotary electric machine according to claim 1 , wherein a flange portion for mounting is formed so as to protrude radially outward from said floor portion.

3. The rotary electric machine according to claim 2 , wherein:

said frame is fitted together with and fixed to an opening end portion at said second end of said cylindrical portion; and

a second stress relieving indented portion is formed around an entire circumference at a second end of an inner circumferential surface of said cylindrical portion such that a gap is formed between a second end portion of an outer circumferential surface of said stator core and said cylindrical portion.

4. The rotary electric machine according to claim 3 , wherein:

a positioning salient portion is formed so as to protrude radially inward from an inner circumferential surface of said cylindrical portion so as to extend from said floor portion toward said second end, said positioning salient portion contacting an outer circumferential edge portion of a first end surface of said stator core.

5. The rotary electric machine according to claim 3 , wherein:

said coils are mounted to said stator core so as to have bobbins interposed that are disposed on two end surfaces of said stator core; and

a positioning salient portion is formed so as to protrude radially inward from an inner circumferential surface of said cylindrical portion so as to extend from said floor portion toward said second end, said positioning salient portion contacting a surface of said bobbins that are disposed on a first end surface of said stator core that faces toward said first end.

6. The rotary electric machine according to claim 2 , wherein:

a positioning salient portion is formed so as to protrude radially inward from an inner circumferential surface of said cylindrical portion so as to extend from said floor portion toward said second end, said positioning salient portion contacting an outer circumferential edge portion of a first end surface of said stator core.

7. The rotary electric machine according to claim 2 , wherein:

said coils are mounted to said stator core so as to have bobbins interposed that are disposed on two end surfaces of said stator core; and

a positioning salient portion is formed so as to protrude radially inward from an inner circumferential surface of said cylindrical portion so as to extend from said floor portion toward said second end, said positioning salient portion contacting a surface of said bobbins that are disposed on a first end surface of said stator core that faces toward said first end.

8. A manufacturing method for a rotary electric machine, being design and manufacturing of the rotary electric machine according to claim 2 , wherein:

a first relationship between an axial length of said first stress relieving indented portion and an amount of displacement of said flange portion is measured using interference between said cylindrical portion and said stator core as a parameter;

said interference and said axial length of said first stress relieving indented portion are determined from results of said measurement of said first relationship such that said amount of displacement of said flange portion becomes less than or equal to a maximum allowable value;

a second relationship between said axial length of said first stress relieving indented portion and said amount of displacement of said flange portion is also measured using said interference and said axial length of said first stress relieving indented portion as determined values and using a thickness of said floor portion as a parameter; and

said thickness of said floor portion is determined from results of said measurement of said second relationship such that said amount of displacement of said flange portion becomes less than or equal to said maximum allowable value.

9. The rotary electric machine according to claim 1 , wherein:

said frame is fitted together with and fixed to an opening end portion at said second end of said cylindrical portion; and

a second stress relieving indented portion forming a groove on said inner circumferential surface of said cylindrical portion is formed around an entire circumference at a second end of an inner circumferential surface of said cylindrical portion such that a gap is formed between a second end portion of an outer circumferential surface of said stator core and said second stress relieving indented portion.

10. The rotary electric machine according to claim 9 , wherein:

a positioning salient portion is formed so as to protrude radially inward from an inner circumferential surface of said cylindrical portion so as to extend from said floor portion toward said second end, said positioning salient portion contacting an outer circumferential edge portion of a first end surface of said stator core.

11. The rotary electric machine according to claim 9 , wherein:

said coils are mounted to said stator core so as to have bobbins interposed that are disposed on two end surfaces of said stator core; and

a positioning salient portion is formed so as to protrude radially inward from an inner circumferential surface of said cylindrical portion so as to extend from said floor portion toward said second end, said positioning salient portion contacting a surface of said bobbins that are disposed on a first end surface of said stator core that faces toward said first end.

12. The rotary electric machine according to claim 1 , wherein:

a positioning salient portion is formed so as to protrude radially inward from an inner circumferential surface of said cylindrical portion so as to extend from said floor portion toward said second end, said positioning salient portion contacting an outer circumferential edge portion of a first end surface of said stator core.

13. The rotary electric machine according to claim 1 , wherein:

said coils are mounted to said stator core so as to have bobbins interposed that are disposed on two end surfaces of said stator core; and

a positioning salient portion is formed so as to protrude radially inward from an inner circumferential surface of said cylindrical portion so as to extend from said floor portion toward said second end, said positioning salient portion contacting a surface of said bobbins that are disposed on a first end surface of said stator core that faces toward said first end.