Electric Motor with Fluid Cooling

Abstract

The present disclosure relates to electric motors having fluid cooling by fluid flow through a cooling jacket cavity. An electric motor may include a cylindrical housing wall, a stator mounted to an inner surface of the housing wall, a motor shaft mounted for rotation within the housing wall, and a cooling jacket wall concentric with and at least partially surrounding the housing wall. A housing wall outer surface and a jacket wall inner surface define a cooling jacket cavity through which cooling fluid flows to draw heat way from the electric motor. Heat slingers, axial or radial fans or the like mounted on one or two ends of the motor shaft extending from the housing wall may further assist in dissipating heat generated by the electric motor.

What is claimed is: 
     
         1 . An electric motor comprising:
 a motor housing having a housing wall having a cylindrical shape, a housing wall inner surface, a housing wall outer surface, a first motor housing end and a second motor housing end;   a stator mounted to the housing wall inner surface;   a motor shaft mounted for rotation within the housing wall and having a first shaft end extending out of the first motor housing end, a second shaft end extending out of the second motor housing end and a shaft longitudinal axis;   a rotor mounted on the motor shaft and aligned with the stator;   a cooling jacket having a jacket wall surrounding and concentric with at least a portion of the housing wall and having a jacket wall inner surface and a jacket wall outer surface, wherein the housing wall outer surface and the jacket wall inner surface define a cooling jacket cavity;   a first heat slinger mounted on the first shaft end; and   a second heat slinger mounted on the second shaft end and disposed within the cooling jacket.   
     
     
         2 . The electric motor of  claim 1 , comprising a fan mounted to the cooling jacket with the second heat slinger dispose between the motor housing and the fan, the fan being operable to generate airflow parallel to the shaft longitudinal axis. 
     
     
         3 . The electric motor of  claim 2 , wherein the fan comprises a direct drive fan that is controllable to rotate independent of the rotation of the motor shaft and the second heat slinger. 
     
     
         4 . The electric motor of  claim 2 , wherein the cooling jacket extends longitudinally toward the first motor housing end and is disposed radially outward from the stator and the rotor such that the airflow generated by the fan flows over the portion of the motor housing surrounding the stator and the rotor. 
     
     
         5 . The electric motor of  claim 1 , wherein the motor housing is mounted on a base plate of a fan mount assembly, and wherein the electric motor comprises an external bearing mounted on the base plate and receiving and supporting the first shaft end. 
     
     
         6 . The electric motor of  claim 5 , wherein the external bearing is disposed between the motor housing and the first heat slinger. 
     
     
         7 . The electric motor of  claim 1 , comprising a floating shaft bearing mounted to the second motor housing end and receiving and supporting the second shaft end, wherein the floating shaft bearing is moveable parallel to the shaft longitudinal axis in response to expansion and contraction of the motor shaft. 
     
     
         8 . An electric motor comprising:
 a motor housing having a housing wall having a cylindrical shape, a housing wall inner surface and a housing wall outer surface;   a stator mounted to the housing wall inner surface;   a motor shaft mounted for rotation within the housing wall and having a shaft longitudinal axis;   a rotor mounted on the motor shaft and aligned with the stator;   a cooling jacket having a jacket wall surrounding and concentric with at least a portion of the housing wall and having a jacket wall inner surface and a jacket wall outer surface, wherein the housing wall outer surface and the jacket wall inner surface define a cooling jacket cavity; and   a cooling fan mounted at an open end of the jacket wall and upstream from the housing wall to discharge air into the cooling jacket cavity, wherein the air discharged from the cooling fan flows longitudinally through the cooling jacket cavity and along the housing wall outer surface.   
     
     
         9 . The electric motor of  claim 8 , wherein the jacket wall has a square cross-section, and wherein the jacket wall inner surface at each corner of the jacket wall and a corresponding portion of the housing wall outer surface define a fluid flow channel for airflow from one end of the jacket wall to an opposite end of the jacket wall. 
     
     
         10 . The electric motor of  claim 9 , wherein the air discharged from the cooling fan flows longitudinally along the housing wall outer surface through the fluid flow channel. 
     
     
         11 . The electric motor of  claim 8 , wherein the housing wall has a plurality of grooves extending longitudinally in the housing wall outer surface and being circumferentially spaced about the housing wall outer surface. 
     
     
         12 . The electric motor of  claim 8 , wherein the motor shaft comprises:
 a motor housing shaft portion disposed within the housing wall with the rotor mounted thereon, wherein the motor housing shaft portion is fabricated from an electrically conductive material; and   an exterior shaft portion connected to the motor housing shaft portion and disposed outward of a first motor housing end of the housing wall, wherein the exterior shaft portion is fabricated from material having a melting point greater than 2200° F.   
     
     
         13 . The electric motor of  claim 8 , wherein a first shaft end of the motor shaft extends out of a first motor housing end of the motor housing and a second shaft end of the motor shaft extends out of a second motor housing end of the motor housing, and wherein the electric motor comprises:
 a first heat slinger mounted on the first shaft end; and   a second heat slinger mounted on the second shaft end and disposed within the cooling jacket cavity.   
     
     
         14 . The electric motor of  claim 13 , wherein the motor housing is mounted on a base plate of a fan mount assembly, and wherein the electric motor comprises an external bearing mounted on the base plate and receiving and supporting the first shaft end. 
     
     
         15 . An electric motor mounted on a base plate of a fan mount assembly, the electric motor comprising:
 a motor housing having a housing wall having a cylindrical shape, a housing wall inner surface, a housing wall outer surface and a motor housing base bracket extending from the housing wall outer surface and affixed to the base plate;   a stator mounted to the housing wall inner surface;   a motor shaft mounted for rotation within the housing wall and having a shaft longitudinal axis and a first shaft end extending from a first motor housing end of the motor housing;   a rotor mounted on the motor shaft and aligned with the stator;   a cooling jacket having a jacket wall surrounding and concentric with at least a portion of the housing wall and having a jacket wall inner surface and a jacket wall outer surface, wherein the housing wall outer surface and the jacket wall inner surface define a cooling jacket cavity; and   an external bearing external to the first motor housing end and mounted on the base plate, wherein the external bearing receives and supports the first shaft end.   
     
     
         16 . The electric motor of  claim 15 , wherein no additional shaft bearing is disposed between the external bearing and the rotor. 
     
     
         17 . The electric motor of  claim 15 , comprising a first heat slinger mounted on the first shaft end with the external bearing disposed between the first motor housing end and the first heat slinger. 
     
     
         18 . The electric motor of  claim 15 , wherein the motor housing has a second motor housing end opposite the first motor housing end and the motor shaft has a second shaft end extending from the second motor housing end, the electric motor comprising a floating shaft bearing mounted to the second motor housing end of the motor housing and receiving and supporting the second shaft end, wherein the floating shaft bearing is moveable parallel to the shaft longitudinal axis in response to expansion and contraction of the motor shaft. 
     
     
         19 . The electric motor of  claim 18 , comprising:
 a first heat slinger mounted on the first shaft end with the external bearing disposed between the first motor housing end and the first heat slinger; and   a second heat slinger mounted on the second shaft end external to the second motor housing end.   
     
     
         20 . The electric motor of  claim 19 , wherein the jacket wall extends away from the second motor housing end to fully enclose the second heat slinger.