External cover-cooled rotary electric machine and casing used therein

1. An external cover-cooled rotary electric machine comprising:

a casing comprising:

a first bracket;

a second bracket; and

a center frame that is held and fastened between end surfaces of said first bracket and said second bracket from two axial ends;

a stator comprising:

an annular stator core that is held so as to be fitted into said center frame; and a stator winding that is mounted into said stator core; and

a rotor that is rotatably supported by said first bracket and said second bracket, and that is rotatably disposed inside said stator,

said external cover-cooled rotary electric machine performing cooling by making a refrigerant flow through said center frame, wherein:

said center frame is formed into a tubular body that has a cylindrical inner circumferential surface;

a first mated recess portion and a second mated recess portion are formed annularly on each of two axial end surfaces of said center frame by a cutting process such that a first inner wall surface that is selected from an inner circumferential inner wall surface and an outer circumferential inner wall surface is formed into a mated surface;

a refrigerant passage through which said refrigerant is made to flow annularly along the center frame is formed inside said center frame so as to have an opening on at least one of said first mated recess portion and said second mated recess portion;

a first mated protrusion and a second mated protrusion are disposed so as to project annularly from respective end surfaces of said first bracket and said second bracket by a cutting process such that a first wall surface that is selected from an inner circumferential wall surface and an outer circumferential wall surface that fits together with said first inner wall surface so as to be mated is formed into a mated surface;

said center frame is fastened to said first bracket and said second bracket by said first mated protrusion and said second mated protrusion being fitted together with said first mated recess portion and said second mated recess portion so as to be mated; and

an elastic sealing member is disposed annularly on an opposite side of whichever mated recess portion of said first mated recess portion and said second mated recess portion said refrigerant passage has said opening from said first inner wall surface so as to be held between an end surface of said center frame and an end surface of whichever bracket of said first bracket and said second bracket faces said mated recess portion;

wherein said refrigerant passage is formed so as to have a cavity shape that does not have an undercut portion in an axial direction, said refrigerant passage is formed inside said center frame so as to have the opening on both said first mated recess portion and said second mated recess portion; and

wherein said refrigerant passage comprises:

a C-shaped first passage that has an opening on said first mated recess portion and that extends circumferentially;

a C-shaped second passage that has an opening on said second mated recess portion, that extends circumferentially, and that is disposed so as to line up with said first passage so as to be separated axially; and

a communicating passage that communicates axially between first end portions of said first passage and said second passage,

said refrigerant passage being configured such that said refrigerant flows in from a second end portion of said first passage, flows through said first passage, said communicating channel, and said second passage, and is then discharged from a second end portion of said second passage.

2. The external cover-cooled rotary electric machine according to claim 1 , wherein a gap is formed between a bottom surface of said second mated recess portion in a portion between said first end portion and said second end portion of said second passage and said second mated protrusion that is fitted together with said second mated recess portion so as to be mated.

3. The external cover-cooled rotary electric machine according to claim 1 , wherein a plurality of rib portions are respectively disposed on an outer circumferential surface of said center frame at a uniform angular pitch circumferentially so as to extend axially from a first axial end to a second axial end.

4. An external cover-cooled rotary electric machine casing comprising:

a first bracket;

a second bracket; and

a center frame that is held and fastened between end surfaces of said first bracket and said second bracket from two axial ends,

said external cover-cooled rotary electric machine casing performing cooling by making a refrigerant flow through said center frame, wherein:

said center frame is formed into a tubular body that has a cylindrical inner circumferential surface;

a first mated recess portion and a second mated recess portion are formed annularly on each of two axial end surfaces of said center frame by a cutting process such that a first inner wall surface that is selected from an inner circumferential inner wall surface and an outer circumferential inner wall surface is formed into a mated surface;

a refrigerant passage through which said refrigerant is made to flow annularly along the center frame is formed inside said center frame so as to have an opening on at least one of said first mated recess portion and said second mated recess portion;

a first mated protrusion and a second mated protrusion are disposed so as to project annularly from respective end surfaces of said first bracket and said second bracket by a cutting process such that a first wall surface that is selected from an inner circumferential wall surface and an outer circumferential wall surface that fits together with said first inner wall surface so as to be mated is formed into a mated surface;

said center frame is fastened to said first bracket and said second bracket by said first mated protrusion and said second mated protrusion being fitted together with said first mated recess portion and said second mated recess portion so as to be mated; and

an elastic sealing member is disposed annularly on an opposite side of whichever mated recess portion of said first mated recess portion and said second mated recess portion said refrigerant passage has said opening from said first inner wall surface so as to be held between an end surface of said center frame and an end surface of whichever bracket of said first bracket and said second bracket faces said mated recess portion;

wherein said refrigerant passage is formed so as to have a cavity shape that does not have an undercut portion in an axial direction, said refrigerant passage is formed inside said center frame so as to have the opening on both said first mated recess portion and said second mated recess portion; and

wherein said refrigerant passage comprises:

a C-shaped first passage that has an opening on said first mated recess portion and that extends circumferentially;

a C-shaped second passage that has an opening on said second mated recess portion, that extends circumferentially, and that is disposed so as to line up with said first passage so as to be separated axially; and

a communicating passage that communicates axially between first end portions of said first passage and said second passage,

said refrigerant passage being configured such that said refrigerant flows in from a second end portion of said first passage, flows through said first passage, said communicating channel, and said second passage, and is then discharged from a second end portion of said second passage.

5. The external cover-cooled rotary electric machine casing according to claim 4 , wherein a gap is formed between a bottom surface of said second mated recess portion in a portion between said first end portion and said second end portion of said second passage and said second mated protrusion that is fitted together with said second mated recess portion so as to be mated.

6. The external cover-cooled rotary electric machine casing according to claim 4 , wherein a plurality of rib portions are respectively disposed on an outer circumferential surface of said center frame at a uniform angular pitch circumferentially so as to extend axially from a first axial end to a second axial end.