Pump with electric motor, immersed in the fluid to be pumped

Abstract

Pump with electric motor, immersed in the fluid to be pumped Circuits for the auxiliary circulation of fluid in the pump for the axial balancing and the cooling of specific portions of the pump. The pump comprises a centrifugal region ( 28 ) with a fluid axial balancing system ( 60 ) and the supply circuit of this balancing system is independent of the or each fluid cooling circuit ( 90, 50, 48, 52, 86 ) of specific elements of the pump such as the motor ( 16 ) and/or a rolling bearing ( 38 ).

1 . Pump with electric motor, immersed in the fluid to be pumped, comprising a casing intended to be plunged into said fluid and accommodating, on the one hand, at least one centrifugal wheel ( 28 ) and, on the other hand, a coaxial electric motor ( 16 ) surmounting said centrifugal wheel and comprising a stator which is integral with said casing and a rotor which is integral with a shaft ( 22 ) coupled to said centrifugal wheel, a first rolling bearing ( 38 ) mounted between said shaft and said casing being installed between said centrifugal wheel and said motor, and an axial balancing system being defined by a fluid circulation circuit provided between said centrifugal wheel and said casing, characterised in that it comprises at least one fluid cooling circuit ( 90 ,  50 ,  48 ,  52 ,  86 ), in particular for said motor and/or said first rolling bearing, and in that said supply circuit of said axial balancing system is independent of the or of each cooling circuit. 
   
   
       2 . Pump according to  claim 1 , characterised in that said fluid cooling circuit of said motor passes through the air gap ( 48 ) of said motor. 
   
   
       3 . Pump according to  claim 2 , characterised in that said motor ( 16 ) is installed in an inner jacket defining therein a lower chamber ( 50 ) between said first rolling bearing ( 38 ) and the motor ( 16 ) and an upper chamber ( 52 ) above said motor, and in that the cooling circuit of the motor extends between inlet orifices ( 90 ) establishing communication between a conduit for evacuating said pumped fluid and said lower chamber and at least one discharge conduct ( 86 ) communicating with the upper chamber. 
   
   
       4 . Pump according to  claim 3 , characterised in that the or each discharge conduct is equipped with a flow rate calibration element ( 88 ). 
   
   
       5 . Pump according to either  claim 3  or  claim 4 , characterised in that a second rolling bearing ( 40 ) is mounted between said shaft and said casing, in said upper chamber. 
   
   
       6 . Pump according to  claim 5 , characterised in that said second rolling bearing ( 40 ) is installed between said upper chamber ( 52 ) and the or each discharge conduit ( 86 ). 
   
   
       7 . Pump according to any one of the preceding claims, characterised in that said axial balancing system ( 60 ) comprises a high-pressure flow space ( 62 ) defined between said casing and a lower face of said centrifugal wheel ( 28 ) and a low-pressure flow space ( 64 ) defined between said casing and an upper face of said centrifugal wheel, and limited radially internally by an annular passage ( 72 ) forming an axially variable flow restriction, reinjection channels ( 80 ) being provided in said centrifugal wheel between an annular discharge space ( 78 ) and the inlet ( 66 ) of said centrifugal wheel, said annular discharge space being defined around said shaft, radially internally in relation to said annular passage ( 72 ) forming the variable flow restriction. 
   
   
       8 . Pump according to  claims 3  and  7  in combination, characterised in that said first rolling bearing ( 38 ) communicates with said annular discharge space ( 78 ) in such a way that the cooling circuit of said first rolling bearing extends between said inlet orifices ( 90 ) and the inlet of said centrifugal wheel via said annular discharge space ( 78 ). 
   
   
       9 . Pump according to  claim 8 , characterised in that a seal ( 92 ) forming a calibrated annular flow restriction is inserted between the recess in said first rolling bearing ( 38 ) and said annular discharge space.