Submerged pump having a bearing lubricated by discharged fluid

Abstract

A target fluid discharged from a pump is partially diverted, by a lead-in duct, into a housing chamber including a motor therein. A top bearing supporting a motor shaft is placed in the lead-in duct, and lubricated by the target fluid flowing through the lead-in duct. A top seal is installed downstream from the top bearing in the lead-in duct. The top seal has a slight gap from the motor shaft to form a throttle structure which increases a flow resistance. The throttle structure maintains a pressure in an area near the top bearing, to thereby suppress presence of gases.

1 . A submersible pump comprising: 
 a pump discharging a target fluid;    a motor located above said pump driving said pump through a shaft;    a housing enclosing said motor;    a bearing supporting said shaft in the vicinity of an upper end of said shaft;    a lead-in duct through which said target fluid discharged from said pump is directed to flow through said bearing from an area near the upper end of said shaft toward an inside of said housing, and    a throttle structure installed downstream from said bearing in said lead-in duct increasing a flow resistance of said lead-in duct.    
   
   
       2 . The submersible pump according to  claim 1 , further comprising a reflux channel for returning said target fluid contained in said housing to said pump, wherein an entrance of said reflux channel is disposed in said housing higher than said bearing.  
   
   
       3 . The submersible pump according to  claim 1 , wherein said throttle structure includes a seal opposing to a surface of said shaft over a predetermined gap.  
   
   
       4 . The submersible pump according to  claim 3 , wherein a labyrinth structure is formed in said seal.  
   
   
       5 . A submersible pump comprising: 
 a pump discharging a target fluid;    a motor located above said pump driving said pump through a shaft;    a housing enclosing said motor;    a lead-in duct communicating a discharge channel of said pump with the inside of said housing;    a bearing supporting said shaft in the vicinity of an upper end of said shaft and located in said lead-in duct, and    a throttle structure installed in said lead-in duct at a place closer to the inside of said housing than said bearing.    
   
   
       6 . A method for lubricating a bearing installed in a submersible pump comprising 
 a pump discharging a target fluid,    a motor located above said pump to drive said pump through a shaft,    a housing enclosing said motor, and    said bearing supporting said shaft disposed near an upper end of said shaft, the method comprising the steps of:    transporting said target fluid discharged from said pump into said housing;    passing said target fluid through said bearing, and    throttling a flow of said target fluid flowing past said bearing to maintain a pressure in an area near said bearing.