Centrifugal pump

Abstract

The present invention relates to a novel bearing arrangement for a centrifugal pump. The bearing arrangement comprises a thrust bearing ( 50 ) arranged closer to the end ( 42 ′) of the shaft ( 42 ) carrying the rotor ( 44 ), the thrust bearing ( 50 ) being selectable between a four-point contact ball bearing for heavy-duty applications and a single row contact ball bearing for light-duty applications.

1 . A centrifugal pump having a shaft ( 42 ) with a first end ( 42 ′) and a second end ( 42 ″), a rotor ( 44 ) coupled to the first end ( 42 ′) of the shaft ( 42 ), an electric motor ( 46 ) for driving the shaft ( 42 ) arranged at the second end ( 42 ″) of the shaft ( 42 ), a bearing housing ( 48 ) supporting the shaft ( 48 ) by means of a first bearing assembly ( 52 ) and a second bearing assembly ( 52 ), the bearing assemblies ( 50 ,  52 ) carrying axial and radial loads subjected to the shaft ( 42 ), the first bearing assembly ( 50 ) being closer to the first end ( 42 ′) of the shaft ( 42 ) than the second bearing assembly ( 52 ), the centrifugal pump ( 40 ) being further provided with a sealing means ( 54 ) positioned around the shaft ( 42 ) and between the rotor ( 44 ) and the first bearing assembly ( 50 ), the first bearing assembly ( 50 ) being a thrust bearing carrying axial loads subjected to the shaft ( 42 ), wherein the thrust bearing ( 50 ) is a four-point contact ball bearing having a split inner ring ( 50   i   1 ,  50   i   2 ) in applications where high load-carrying capacity is required, and a single row contact ball bearing in applications where low load-carrying capacity is required, whereby in both load conditions;
 OR 
 wherein the same bearing housing ( 48 ) is used with the thrust bearing ( 50 ) being a four-point contact ball bearing having a split inner ring ( 50   i   1 ,  50   i   2 ) in applications where high load-carrying capacity is required, and with a single row contact ball bearing in applications where low load-carrying capacity is required; and 
 OR 
 wherein the thrust bearing ( 50 ) is a four-point contact ball bearing having a split inner ring ( 50   i   1 ,  50   i   2 ). 
 
     
     
         2 . The centrifugal pump as recited in  claim 1 , wherein the bearing housing ( 48 ) is, at its first end ( 48 ′), attached to a housing ( 78 ) of a centrifugal pump ( 40 ) and, at its second end ( 48 ″), to the electric motor ( 46 ). 
     
     
         3 . The centrifugal pump as recited in  claim 1 , wherein the electric motor ( 46 ) has a rotor ( 82 ) and a stator ( 86 ), the rotor ( 82 ) being coupled to the shaft ( 42 ) of the centrifugal pump ( 40 ) and the stator ( 86 ) to the second end ( 48 ″) of the bearing housing ( 48 ). 
     
     
         4 . The centrifugal pump as recited in  claim 3 , wherein the rotor ( 82 ) is fixed on the shaft ( 42 ) by means of a taper drive sleeve. 
     
     
         5 . The centrifugal pump as recited in  claim 3 , wherein the bearing housing ( 48 ) has at its second end ( 48 ″) means ( 84 ) for fastening the stator ( 86 ) to the housing ( 48 ). 
     
     
         6 . The centrifugal pump as recited in  claim 1 , wherein the second bearing assembly ( 52 ) is formed of a single row ball bearing or a roller bearing. 
     
     
         7 . The centrifugal pump as recited in  claim 3 , wherein a fan impeller ( 92 ) for cooling the electric motor ( 46 ), the impeller ( 92 ) being attached to an additional shaft ( 90 ). 
     
     
         8 . The centrifugal pump as recited in  claim 7 , wherein the additional shaft is attached to the second end ( 42 ″) of the shaft ( 42 ). 
     
     
         9 . The centrifugal pump as recited in  claim 1 , wherein the first bearing assembly ( 50 ) is secured axially on the shaft ( 42 ) by means of a snap ring ( 66 ) and distance ring ( 64 ) or by means of a lock nut and a lock washer. 
     
     
         10 . The centrifugal pump as recited in  claim 1 , wherein the shaft ( 42 ) is sealed by means of labyrinth seals ( 74 ) and ( 60 ) in a bearing cover ( 72 ) and the bearing housing ( 48 ).