Electronic fluid pump

Abstract

A fluid pump includes a pump housing having a housing cavity with an inlet and an outlet. An encapsulated stator assembly is positioned within the housing cavity and at least partially defines a fluid passage from the inlet to the outlet. A polymeric capsule member encloses and seals the encapsulated stator assembly, protecting the motor from, and providing heat transfer to, the working fluid. A stator provides a magnetic field which drives a rotor assembly. The rotor assembly rotates an impeller for pumping fluid from the inlet to the outlet.

What is claimed is:  
     
         1 . A fluid pump for pumping liquid, comprising: 
 a motor housing assembly having an inlet housing, a stator housing assembly, and an outlet housing;    wherein the stator housing assembly includes a substantially cylindrical metal case and an encapsulated stator assembly enclosed and sealed by a polymeric capsule member, and the polymeric capsule member defines a rotor cavity;    an impeller rotatably positioned in the inlet housing and having an impeller axis; and    a rotor assembly rotatably located inside the rotor cavity and connected to the impeller for rotating the impeller for pumping liquid from the inlet housing to the outlet housing.    
     
     
         2 . The fluid pump of  claim 1 , wherein the inlet housing and outlet housing are fastened together to secure the stator housing assembly therebetween.  
     
     
         3 . The fluid pump of  claim 1 , wherein the metal case includes liquid flow passages formed therein by diffuser vanes and inner and outer walls of the metal case, thereby completely defining the liquid flow passages.  
     
     
         4 . The fluid pump of  claim 1 , wherein the polymeric capsule member comprises a thermally conductive, electrically insulative material.  
     
     
         5 . The fluid pump of  claim 1  wherein the stator housing assembly further includes a front cover and a rear cover plugging opposing ends of the rotor cavity.  
     
     
         6 . The fluid pump of  claim 5 , further comprising inlet diffuser vanes formed on the front cover.  
     
     
         7 . The fluid pump of  claim 1 , wherein the rotor assembly includes a rotor with a rotor shaft.  
     
     
         8 . The fluid pump of  claim 7 , wherein the rotor shaft is supported by a front bearing and a rear bearing.  
     
     
         9 . The fluid pump of  claim 8 , wherein the rear cover contains a bearing seat for locating the rear bearing.  
     
     
         10 . A method of manufacturing an encapsulated stator assembly, comprising: 
 providing a front cover and a rear cover;    providing a hollow, substantially cylindrical metal case with a longitudinal axis and two open ends;    locating a stator assembly within the metal case;    temporarily capping the two open ends and encapsulating the stator assembly in a polymeric material; and    uncapping the two ends and attaching the front cover and the rear cover to the metal case.    
     
     
         11 . The method of  claim 10 , wherein the polymeric material is thermally conductive and electrically insulative.  
     
     
         12 . The method of  claim 10 , wherein the metal case includes liquid flow passages formed therein by diffuser vanes and inner and outer walls of the metal case, thereby completely defining the liquid flow passages.  
     
     
         13 . The method of  claim 10 , wherein the front cover includes diffuser vanes formed thereon.  
     
     
         14 . The method of  claim 10 , wherein encapsulating the stator assembly in the polymeric material includes forming a cavity therethrough.  
     
     
         15 . The method of  claim 14 , wherein the front and rear covers are each configured to receive a bearing to support a shaft disposed within the cavity.