Pump assembly

Abstract

A pump assembly (1) includes a rotor axle (45), an impeller (12) fixed to the rotor axle, and a pump housing (11) accommodating the impeller and defining a radial inner reference surface (71). A drive motor includes a stator (17) and a rotor (51). The rotor is fixed to the rotor axle for driving the impeller. A rotor can (57) accommodates the rotor and includes a rotor can flange (63). A stator housing (13) accommodates the stator. A radial bearing ring (47) is in sliding contact with the rotor axle. A bearing retainer (41) engages the radial bearing ring and centers the radial bearing ring with respect to the radial inner reference surface. The rotor can flange has a radial distance to the pump housing. The rotor can includes a radial inner centering surface (65) centered by radially abutting against a radial outer centering surface (67) of the bearing retainer.

What is claimed is: 
     
         1 . A pump assembly comprising:
 a rotor axle extending along a rotor axis;   an impeller fixed to the rotor axle;   a pump housing accommodating the impeller, wherein the pump housing defines a first radial inner reference surface;   a drive motor comprising a stator and a rotor, wherein the rotor is fixed to the rotor axle for driving the impeller;   a rotor can accommodating the rotor, wherein the rotor can comprises a rotor can flange;   a stator housing accommodating the stator;   a first radial bearing ring in sliding contact with the rotor axle; and   a bearing retainer engaging the first radial bearing ring and centering the first radial bearing ring with respect to the first radial inner reference surface of the pump housing, wherein the rotor can flange has a radial distance to the pump housing and the rotor can further comprises a radial inner centering surface that is centered by radially abutting against a radial outer centering surface of the bearing retainer.   
     
     
         2 . The pump assembly according to  claim 1 , wherein:
 the radial inner centering surface of the rotor can has at least three radial projections; or   the radial outer centering surface of the bearing retainer has at least three radial projections; or   the radial inner centering surface of the rotor can and the radial outer centering surface of the bearing retainer have at least three radial projections.   
     
     
         3 . The pump assembly according to  claim 1 , wherein the bearing retainer comprises a radial outer bearing retainer surface having at least three radial projections radially abutting against the first radial inner reference surface of the pump housing and centering the bearing retainer with respect to the first radial inner reference surface of the pump housing. 
     
     
         4 . The pump assembly according to  claim 1 , wherein:
 the rotor can flange forms a circumferential U-shaped groove with a radial inner section and a radial outer section; and   the radial inner section forms the radial inner centering surface of the rotor can.   
     
     
         5 . The pump assembly according to  claim 1 , wherein the rotor can flange comprises an annular stop surface facing away from the impeller. 
     
     
         6 . The pump assembly according to  claim 5 , further comprising a locking ring secured in a circumferential groove of the pump housing, wherein the annular stop surface axially abuts against the locking ring. 
     
     
         7 . The pump assembly according to  claim 1 , wherein:
 the rotor can flange comprises an annular contact surface facing towards the impeller and the bearing retainer comprises an annular biasing surface facing away from the impeller; and   the bearing retainer is resiliently preloaded for biasing the annular biasing surface of the bearing retainer against the annular contact surface of the rotor can flange.   
     
     
         8 . The pump assembly according to  claim 7 , wherein:
 the annular contact surface of the rotor can flange has at least three axial projections; or   the annular biasing surface of the bearing retainer has at least three axial projections; or   the annular contact surface of the rotor can flange and the annular biasing surface of the bearing retainer have at least three axial projections.   
     
     
         9 . The pump assembly according to  claim 1 , further comprising a neck ring fixed to the pump housing, wherein:
 the impeller is located axially between the bearing retainer and the neck ring;   the neck ring comprises a cylindrical section at least partially extending into the impeller.   
     
     
         10 . The pump assembly according to  claim 9 , wherein:
 the cylindrical section comprises a radial outer gap surface;   the impeller comprises a radial inner gap surface; and   the radial outer gap surface of the cylindrical section and the radial inner gap surface of the impeller have a radial distance defining a gap.   
     
     
         11 . The pump assembly according to  claim 1 , wherein:
 the pump housing defines a first annular reference surface facing away from the impeller;   the stator housing defines a second annular reference surface facing towards the impeller;   the second annular reference surface is biased against the first annular reference surface.   
     
     
         12 . The pump assembly according to  claim 11 , wherein:
 the stator defines a second radial inner reference surface; and   the rotor can further comprises a radial outer alignment surface aligned perpendicular to the first annular reference surface of the pump housing by radially abutting against the second radial inner reference surface of the stator.   
     
     
         13 . The pump assembly according to  claim 11 , wherein
 the first annular reference surface is located radially more outward than the first radial inner reference surface; or   the first annular reference surface is located axially further away from the impeller than the first radial inner reference surface; or   the first annular reference surface is located radially more outward than the first radial inner reference surface and the first annular reference surface is located axially further away from the impeller than the first radial inner reference surface.   
     
     
         14 . The pump assembly according to  claim 12 , wherein:
 the second radial inner reference surface is located radially more inward than the second annular reference surface; or   the second radial inner reference surface is located axially further away from the impeller than the second annular reference surface; or   the second radial inner reference surface is located radially more inward than the second annular reference surface and the second radial inner reference surface is located axially further away from the impeller than the second annular reference surface.   
     
     
         15 . The pump assembly according to  claim 1 , further comprising a bayonet ring securing the stator housing to the pump housing, wherein the bayonet ring is resiliently preloaded for axially biasing the stator housing against the pump housing towards the impeller.