Centering coupling for electrical submersible pump splined shafts

Abstract

An electrical submersible well pump assembly having a pump, a pump motor, and a seal section. The motor drives the pump via shafts rotatingly coupled with a coupling assembly. The coupling assembly includes an alignment device that maintains the shaft ends in coaxial alignment. The alignment device compressibly engages one or both of the shafts. The alignment device may be an elongated member having slots cut along its length on one or both ends configured to compress when inserted into a bore coaxially formed into the shaft ends within the coupling assembly.

1 . A submersible pumping system for pumping wellbore fluid, comprising:
 a pump motor;   a splined shaft coupling;   a motor shaft having a splined end rotatably affixed within one end of the shaft coupling, the motor shaft being rotatable by the motor;   a driven shaft having a splined end rotatably affixed within an opposite end of the shaft coupling opposite to the motor shaft, the respective ends of the motor shaft and driven shaft being substantially coaxial within the shaft coupling;   a bore formed into the splined end of each shaft; and   a radially compressible element inserted within the motor shaft bore on one end and the driven shaft bore on its other end.   
     
     
         2 . The pumping system of  claim 1 , the compressible element comprising a body, a slot formed in the body, the slot axially extending along a portion of the element body axis, wherein the slot defines body sections on its outer periphery. 
     
     
         3 . The pumping system of  claim 2 , the slot bisecting the element body. 
     
     
         4 . The pumping system of  claim 2 , further comprising an optional second slot axially extending along a portion of the element body axis to bisect the element body. 
     
     
         5 . The pumping system of  claim 2  further comprising an additional slot extending along a portion of the element body axis. 
     
     
         6 . The pumping system of  claim 5 , the slots forming more than two body sections. 
     
     
         7 . The pumping system of  claim 2  further comprising a filler material within the slot. 
     
     
         8 . The pumping system of  claim 2 , wherein the compressible element is substantially cylindrical. 
     
     
         9 . The pumping system of  claim 1 , wherein the coupling has internal square tooth splines. 
     
     
         10 . A submersible pumping system for pumping wellbore fluid, comprising:
 a pump motor;   a splined shaft coupling;   a motor shaft having a splined end rotatably affixed within one end of the shaft coupling, the motor shaft being rotatable by the motor;   a driven shaft having a splined end rotatably affixed within an opposite end of the shaft coupling opposite to the motor shaft, the respective ends of the motor shaft and driven shaft being substantially coaxial within the shaft coupling;   an annular sleeve circumscribing a portion of one of the shafts disposed within the shaft coupling; and   flexible protrusions formed on the sleeve, the protrusions being compressible between the shaft and the shaft coupling.   
     
     
         11 . The pumping system of  claim 10 , wherein the annular sleeve comprises a tolerance ring. 
     
     
         12 . The pumping system of  claim 10 , further comprising a second annular sleeve circumscribing a portion of the other one of the shafts disposed within the shaft coupling. 
     
     
         13 . The pumping system of  claim 10 , wherein the annular sleeve axially extends within the shaft coupling and circumscribes a portion of the other shaft disposed within the shaft coupling. 
     
     
         14 . The pumping system of  claim 10 , the protrusions extending from the sleeve outer surface. 
     
     
         15 . The pumping system of  claim 10 , the protrusions extending from the sleeve inner surface. 
     
     
         16 . A submersible pumping system for pumping wellbore fluid, comprising:
 a pump motor;   a splined shaft coupling;   a motor shaft having a splined end rotatably affixed within one end of the shaft coupling, the motor shaft being rotatable by the motor;   a driven shaft having a splined end rotatably affixed within an opposite end of the shaft coupling opposite to the motor shaft, the respective ends of the motor shaft and driven shaft being substantially coaxial within the shaft coupling; and   an alignment element in compressed engagement with at least one of the motor shaft or the driven shaft, the motor shaft and the driven shaft being substantially coaxially aligned.   
     
     
         17 . The submersible pumping system of  claim 16  wherein the alignment element comprises an elongated member comprising a body, a slot formed in the body, the slot axially extending along a portion of the element body axis, wherein the slot defines body sections on its outer periphery. 
     
     
         18 . The submersible pumping system of  claim 16 , wherein the alignment element comprises an annular sleeve circumscribing a portion of one of the shafts disposed within the shaft coupling; and flexible protrusions formed on the sleeve, the protrusions compressible between the shaft and the shaft coupling. 
     
     
         19 . The submersible pumping system of  claim 18 , further comprising a second annular sleeve circumscribing a portion of the other one of the shafts disposed within the shaft coupling. 
     
     
         20 . The pumping system of  claim 18 , wherein the annular sleeve axially extends within the shaft coupling and circumscribes a portion of the other shaft disposed within the shaft coupling.