Airtight-type electric motor

1. An airtight-type electric motor comprising:

a rotor including a rotor member and a shaft with the rotor member fixed thereto;

a stator including a stator core located radially outside of the shaft and a plurality of winding portions mounted on the stator core, the stator core including core end portions which oppose to each other in an axial direction of the shaft;

a cylindrical housing that is located radially outside of the stator and surrounds the stator, the housing including housing end portions which oppose to each other in the axial direction, wherein the housing is not in direct contact with the stator core;

a pair of bearings that rotatably support the shaft;

a pair of end brackets with the pair of bearings respectively fixed thereto, the pair of end brackets being fixed to the core end portions of the stator core through fitting structures,

each of the end brackets comprising:

a bracket body;

an inside rib integrally formed with the bracket body and inserted into inside the stator core to be fitted into the core end portion of the stator core, wherein the bearing is fitted into inside of the inside rib; and

an annular outside rib integrally formed with the bracket body and located radially outside of the inside rib to be inserted into inside the housing end portion, and

a pair of airtight coupling structures which airtightly couple the end brackets to the housing end portions,

each of the airtight coupling structures comprising:

a first O-ring arranged between the outside rib and an inner circumferential surface of the housing end portion; and

a second O-ring arranged between an end surface of the housing end portion and the bracket body of the end bracket,

wherein the outside rib is in contact against an end surface of the core end portion of the stator core and is airtightly coupled to the housing end portion of the housing through the airtight coupling structure.

2. The airtight-type electric motor according to claim 1 , wherein

an annular groove that opens radially toward an outside of the outside rib is formed in the outside rib, and the first O-ring is fitted into the annular groove.

3. The airtight-type electric motor according to claim 2 , wherein

an annular O-ring positioning corner portion is formed between an inner surface of the bracket body of the end bracket and an outer circumferential surface of the outside rib, the second O-ring being arranged thereon.

4. The airtight-type electric motor according to claim 1 , wherein

a plurality of assembling through-holes are formed in the bracket body of one of the pair of end brackets to insert a plurality of fastening screw members therein;

a plurality of screw holes are formed in the bracket body of the other of the pair of end brackets to screw threaded portions formed at tip portions of the fastening screw members therein; and

with the shaft of the rotor being supported by the pair of bearings fixed to the pair of end brackets; the stator and the housing being arranged between the pair of end brackets; and the pair of airtight coupling structures being arranged between the end brackets and the housing end portions, the fastening screw members are inserted into the assembling through-holes formed in the bracket body of the one of the pair of end brackets and the threaded portions of the fastening screw members are screwed into the screw holes formed in the bracket body of the other of the pair of end brackets, thereby pressing the outside ribs of the end brackets against the end surfaces of the core end portions of the stator core and pressing the end brackets against the housing through the second O-rings.

5. The airtight-type electric motor according to claim 2 , wherein

a plurality of assembling through-holes are formed in the bracket body of one of the pair of end brackets to insert a plurality of fastening screw members therein;

a plurality of screw holes are formed in the bracket body of the other of the pair of end brackets to screw threaded portions formed at tip portions of the fastening screw members therein; and

with the shaft of the rotor being supported by the pair of bearings fixed to the pair of end brackets; the stator and the housing being arranged between the pair of end brackets; and the pair of airtight coupling structures being arranged between the end brackets and the housing end portions, the fastening screw members are inserted into the assembling through-holes formed in the bracket body of the one of the pair of end brackets and the threaded portions of the fastening screw members are screwed into the screw holes formed in the bracket body of the other of the pair of end brackets, thereby pressing the outside ribs of the end brackets against the end surfaces of the core end portions of the stator core and pressing the end brackets against the housing through the second O-rings.

6. The airtight-type electric motor according to claim 3 , wherein

a plurality of assembling through-holes are formed in the bracket body of one of the pair of end brackets to insert a plurality of fastening screw members therein;

a plurality of screw holes are formed in the bracket body of the other of the pair of end brackets to screw threaded portions formed at tip portions of the fastening screw members therein; and

with the shaft of the rotor being supported by the pair of bearings fixed to the pair of end brackets; the stator and the housing being arranged between the pair of end brackets; and the pair of airtight coupling structures being arranged between the end brackets and the housing end portions, the fastening screw members are inserted into the assembling through-holes formed in the bracket body of the one of the pair of end brackets and the threaded portions of the fastening screw members are screwed into the screw holes formed in the bracket body of the other of the pair of end brackets, thereby pressing the outside ribs of the end brackets against the end surfaces of the core end portions of the stator core and pressing the end brackets against the housing through the second O-rings.