Electric Water Pump With Stator Cooling

Abstract

An electric pump comprises an outer housing including a motor cavity and a controller cavity separated by a partition wall. An inner housing is positioned within the motor cavity of the outer housing. One of the inner and outer housings includes radially extending ribs positioned adjacent to the other of the inner and outer housings to define a coolant flow path between the inner housing and the outer housing. The flow path is partially defined by the partition wall. An electric motor is positioned within the inner housing and includes a hollow rotor shaft driving a pump member. The hollow rotor shaft forms a portion of the coolant path and interconnects a volume between the inner and outer housings with a low pressure cavity containing the pump member. A controller is positioned within the controller cavity in heat transfer relation with the partition wall.

What is claimed is: 
     
         1 . An electric pump comprising:
 an outer housing including a motor cavity and a controller cavity separated by a partition wall;   an inner housing positioned within the motor cavity of the outer housing, one of the inner and outer housings including radially extending ribs positioned adjacent to the other of the inner and outer housings to define a coolant flow path between the inner housing and the outer housing, the flow path being partially defined by the partition wall;   a pump member;   an electric motor positioned within the inner housing and including a hollow rotor shaft driving the pump member, the hollow rotor shaft forming a portion of the coolant path and interconnecting a volume between the inner and outer housings with a low pressure cavity containing the pump member; and   a controller positioned within the controller cavity in heat transfer relation with the partition wall.   
     
     
         2 . The electric pump of  claim 1 , wherein the ribs define a single circuitous flow path. 
     
     
         3 . The electric pump of  claim 2 , wherein the flow path includes substantially parallel portions where the flow is in an opposite direction. 
     
     
         4 . The electric pump of  claim 3 , wherein the parallel portions extend substantially parallel to an axis of rotor shaft rotation. 
     
     
         5 . The electric pump of  claim 1 , wherein one of the ribs axially extends along substantially the entire length of the inner housing and an adjacent one of the ribs has a lesser length to allow fluid to pass across an end face of the adjacent rib. 
     
     
         6 . An electric pump comprising:
 an outer housing including a motor cavity and a controller cavity separated by a partition wall;   an inner housing positioned within the motor cavity of the outer housing, one of the inner and outer housings including radially extending ribs positioned adjacent to the other of the inner and outer housings to define a coolant flow path between the inner housing and the outer housing, the flow path being partially defined by the partition wall;   a pump member;   an electric motor positioned within the inner housing and including a stator and a rotor, the rotor being fixed to a solid rotor shaft for driving the pump member;   a cylindrical sleeve separating the stator and the rotor, an area between the sleeve and the rotor forming a portion of the coolant path and interconnecting a volume between the inner and outer housings with a low pressure cavity containing the pump member; and   a controller positioned within the controller cavity in heat transfer relation with the partition wall.   
     
     
         7 . The electric pump of  claim 6 , wherein the pump member and the inner housing each include an aperture in receipt of the fluid flowing between the rotor and the sleeve to complete the coolant path. 
     
     
         8 . The electric pump of  claim 7 , wherein the flow path includes substantially parallel portions where the flow is in an opposite direction. 
     
     
         9 . The electric pump of  claim 8 , wherein the parallel portions are circumferentially spaced apart and extend substantially parallel to an axis of rotor shaft rotation. 
     
     
         10 . The electric pump of  claim 6 , wherein one of the ribs axially extends along substantially the entire length of the inner housing and an adjacent one of the ribs has a lesser length to allow fluid to pass across an end face of the adjacent rib. 
     
     
         11 . The electric pump of  claim 6 , wherein the stator is positioned in a sealed cavity devoid of coolant. 
     
     
         12 . The electric pump of  claim 6 , wherein the sleeve includes a radially extending flange capping an open end of the inner housing. 
     
     
         13 . The electric pump of  claim 12 , further including wire apertures extending through the flange interconnecting the controller cavity and the sealed cavity. 
     
     
         14 . The electric pump of  claim 12 , wherein the sleeve flange includes a wall defining a portion of the coolant flow path that extends transverse to the axis of rotor shaft rotation. 
     
     
         15 . The electric pump of  claim 14 , wherein the sleeve flange wall is interrupted by a port allowing coolant flow from the coolant path portion between the inner and outer housings to a location between the sleeve and the rotor. 
     
     
         16 . The electric pump of  claim 6 , wherein the coolant path branches into two channels flowing in parallel with each other and reconnects at a reservoir in fluid communication with the rotor. 
     
     
         17 . The electric pump of  claim 6 , wherein each of the outer housing, the inner housing, and the sleeve each include substantially cylindrically shaped portions co-axially aligned along a rotor axis of rotation. 
     
     
         18 . The electric pump of  claim 6 , wherein a portion of the partition wall includes an increased thickness, the controller being directly engaged with the increased thickness portion. 
     
     
         19 . The electric pump of  claim 6 , wherein the outer housing includes a boss in receipt of a rotor shaft bushing.