Power Dense Motor With Thermal Management Capability

Abstract

An electric machine has a housing which has an interior space and an interior wall extending about the interior space, and a stator assembly disposed within the interior space and attached to the interior wall. The electric machine includes a rotor within the interior space and located radially inward from the stator. The rotor and stator define a gap there between and cooperate to produce flux. The rotor comprises a hollow cylindrical member having an interior region, an interior wall extending about the interior region and an exterior surface. The rotor includes magnets attached to the exterior surface and a rotor shaft support structure disposed within the interior region of the hollow cylindrical member and attached to the interior wall of the hollow cylindrical member. A rotor shaft is attached to the rotor shaft support structure. The electric machine further comprises bearings to locate and support the rotor shaft relative to the housing.

1 . An electric machine comprising:
 a housing having an interior space and an interior wall extending about the interior space;   a stator assembly disposed within the interior space of the housing and attached to the interior wall;   a rotor located within the interior space and radially inward from the stator, wherein the rotor and stator define a gap there between and cooperate to produce flux, the rotor comprising a hollow cylindrical member having an interior region, an interior wall extending about the interior region and an exterior surface, the rotor further comprises magnets attached to the exterior surface, a rotor shaft support structure disposed within the interior region and attached to the interior wall of the hollow cylindrical member, and a rotor shaft attached to the rotor shaft support structure; and   bearings to locate and support the rotor shaft relative to the housing.   
     
     
         2 . The electric machine according to  claim 1  wherein the hollow cylindrical member comprises a first end and an opposite second end, the hollow cylindrical member comprising a fan structure on the first end to circulate air within the motor interior as the rotor rotates. 
     
     
         3 . (canceled) 
     
     
         4 . The electric machine according to  claim 1  wherein the magnets are spaced apart on the hollow cylindrical member. 
     
     
         5 . The electric machine according to  claim 4  wherein the rotor has at least one thru-hole in the hollow cylindrical member that is located between a pair of adjacent magnets. 
     
     
         6 . The electric machine according to  claim 5  wherein the at least one thru-hole in the hollow cylindrical member comprises a plurality of thru-holes arranged in consecutive order. 
     
     
         7 . The electric machine according to  claim 4  wherein the rotor has at least one dimple formed in the hollow cylindrical member between a pair of adjacent magnets. 
     
     
         8 . The electric machine according to  claim 7  wherein the at least one dimple formed in the hollow cylindrical member comprises a plurality of dimples arranged in consecutive order. 
     
     
         9 . The electric machine according to  claim 4  further comprising a fan blade attached to the hollow cylindrical member between a pair of adjacent magnets. 
     
     
         10 . The electric machine according to  claim 4  further comprising a fan blade integrally formed on the hollow cylindrical member and located between a pair of adjacent magnets. 
     
     
         11 . The electric machine according to  claim 4  further comprising a cooling groove formed in the hollow cylindrical member between a pair of adjacent magnets. 
     
     
         12 . The electrical machine according to  claim 1  wherein the magnets are surface permanent magnets. 
     
     
         13 . The electrical machine according to  claim 1  wherein the magnets are interior permanent magnets. 
     
     
         14 . (canceled) 
     
     
         15 . The electric machine according to  claim 1  wherein the stator assembly comprises a plurality of lamination sheets stacked together to form a stack, wherein each lamination sheet has a thickness of about 0.0185 inch. 
     
     
         16 . The electrical machine according to  claim 15  wherein the laminated sheets are bonded together with a silicone epoxy resin having a thermal conductivity of about 0.7 W/m-c. 
     
     
         17 . The electrical machine according to  claim 15  wherein the stator assembly further comprises a stator winding having a plurality of winding end turns. 
     
     
         18 . The electrical machine according to  claim 17  further comprising a thermally conductive material disposed between the winding end turns and interior wall of the housing so as to create a heat path from the winding end turns, through the stack of lamination sheets and to the housing. 
     
     
         19 . The electrical machine according to  claim 17  wherein the housing has a pair of cover members, each cover being configured to encapsulate the winding end turns so as to cause transfer of heat from the winding end turns to the cover. 
     
     
         20 . The electrical machine according to  claim 19  wherein a first one of the covers has an opening through which the rotor shaft extends, and wherein the electrical machine further comprises a sealing device to create a seal between the rotor shaft and the first one of the covers. 
     
     
         21 . The electrical machine according to  claim 19  wherein the rotor defines a center line of the motor and wherein each cover has an exterior surface that is configured with cooling fins that extend radially from the center line of the motor. 
     
     
         22 . The electrical machine according to  claim 1  wherein the rotor defines a center line of the motor and the housing further comprises an exterior surface that is configured with a plurality of cooling fins that extend parallel to the center line of the motor.