Pump assembly

Abstract

A pump assembly includes a rotor axle, an impeller and a pump housing defining a radial inner reference surface. A drive motor includes a stator accommodated in stator housing and a rotor accommodated in a rotor can. A radial bearing ring is in sliding contact with the rotor axle. A bearing retainer engages the radial bearing ring and centers it with respect to the radial inner reference surface. A neck ring is coupled to the pump housing and has a circumferential wall section. The impeller is located axially between the bearing retainer and the neck ring. The circumferential wall section at least partially extends into the impeller or the impeller at least partially extends into the circumferential wall section. The circumferential wall section includes a cylindrical radial outer surface and a cylindrical radial inner surface. The radial outer surface is eccentric with respect to the radial inner surface.

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;   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; and   a neck ring coupled to the pump housing, wherein: the impeller is located axially between the bearing retainer and the neck ring; the neck ring comprises a circumferential wall section; the circumferential wall section at least partially extends into the impeller or the impeller at least partially extends into the circumferential wall section; the circumferential wall section of the neck ring comprises a cylindrical radial outer surface and a cylindrical radial inner surface; and the radial outer surface is eccentric with respect to the radial inner surface.   
     
     
         2 . The pump assembly according to  claim 1 , wherein:
 the impeller comprises a radial surface;   the radial outer surface or the radial inner surface of the circumferential wall section has a radial distance to the radial surface of the impeller defining a gap.   
     
     
         3 . The pump assembly according to  claim 1 , wherein the radial outer surface or the radial inner surface of the circumferential wall section of the neck ring is coaxial with the first radial inner reference surface and the rotor axis. 
     
     
         4 . The pump assembly according  claim 1 , wherein the radial outer surface or the radial inner surface of the circumferential wall section of the neck ring is a machined surface with a milling edge extending along at least a portion of the circumference of the circumferential wall section of the neck ring. 
     
     
         5 . The pump assembly according  claim 1 , wherein:
 the rotor can flange has a radial distance to the pump housing; and   the rotor can comprises a radial inner centering surface, centered by radially abutting against a radial outer centering surface of the bearing retainer.   
     
     
         6 . The pump assembly according to  claim 5 , 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 has and the radial outer centering surface of the bearing retainer have at least three radial projections.   
     
     
         7 . The pump assembly according to  claim 5 , 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 
     
     
         8 . The pump assembly according  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.   
     
     
         9 . The pump assembly according  claim 1 , wherein the rotor can flange comprises an annular stop surface facing away from the impeller. 
     
     
         10 . The pump assembly according to  claim 9 , further comprising a locking ring being secured in a circumferential groove of the pump housing, wherein the annular stop surface axially abuts against the locking ring. 
     
     
         11 . The pump assembly according  claim 1 , wherein:
 the rotor can flange comprises an annular contact surface facing towards the impeller;   the bearing retainer comprises an annular biasing surface facing away from the impeller;   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.   
     
     
         12 . The pump assembly according to  claim 11 , 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.   
     
     
         13 . A method of manufacturing 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, 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, the method comprising the steps of:
 coupling a neck ring to the pump housing;   defining a first radial inner reference surface by machining the pump housing; and   defining a radial outer surface or a radial inner surface by machining a circumferential wall section of the neck ring so that the radial outer surface or the radial inner surface is coaxial with the first radial inner reference surface.   
     
     
         14 . The method according to  claim 13 , wherein the steps of defining the first radial inner reference surface and defining the radial outer surface or the radial inner surface are performed after the step of coupling the neck ring to the pump housing. 
     
     
         15 . The method according to  claim 13 , wherein the steps of defining the first radial inner reference surface and defining the radial outer surface or the radial inner surface are performed with the same machining tool, wherein the fastening of the pump housing in the machining tool is maintained between these two defining steps. 
     
     
         16 . The method according to  claim 13 , further comprising a step of defining a first annular reference surface by machining the pump housing, wherein all defining steps are performed with the same machining tool, wherein the fastening of the pump housing in the machining tool is maintained between the defining steps.