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 maintains the shaft ends in coaxial alignment with an alignment device. The alignment device is profiled on opposite ends for mating engagement with the centering profiles on the shaft ends.

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 guide profile on the splined end of each shaft; and   an alignment element mounted in the shaft coupling, the element coaxially engaging the guide profiles on the ends of the motor shaft and driven shaft within the shaft coupling.   
   
   
       2 . The pumping system of  claim 1 , further comprising a first centering guide on one side of the alignment element and a second centering guide on the alignment element opposite side, the first centering guide being substantially coaxial with the second centering guide each centering guide engaging a corresponding guide profile. 
   
   
       3 . The pumping system of  claim 2  wherein the first and second centering guides selectively comprise a protrusion or a recess. 
   
   
       4 . The pumping system of  claim 1  wherein the guide profiles on the shafts are conical and located on each shaft axis. 
   
   
       5 . The pumping system of  claim 1 , wherein the guide profiles comprise a protrusion or a recess. 
   
   
       6 . The pumping system of  claim 1 , wherein the coupling has internal square tooth splines. 
   
   
       7 . The pumping system of  claim 1 , wherein the alignment member comprises a disk mounted in the coupling, the disk being perpendicular to the coupling axis. 
   
   
       8 . The pumping system of  claim 1  further comprising a shoulder formed in the coupling, and a threaded sleeve secured within the coupling, wherein the alignment element comprises a disk secured between the shoulder and the sleeve. 
   
   
       9 . The pumping system of  claim 1 , wherein the alignment element comprises upper and lower housings that telescope relative to one another, and a resilient member. 
   
   
       10 . An electrical submersible pump (ESP) comprising:
 a pump motor;   a motor shaft mechanically affixed to the pump motor;   a driven shaft;   a splined coupling rotatingly coupling respective splined ends of the motor shaft and the driven shaft;   a tapered centering profile on the splined ends of each shaft coaxial with each shaft axis; and   an alignment device mounted in the coupling the alignment device having a tapered guide profile on one side that mates with the centering profile on the motor shaft and a tapered guide profile on an opposite side that mates with the centering profile on the driven shaft.   
   
   
       11 . The ESP of  claim 10  wherein the tapered centering profiles and the tapered guide profiles are conical. 
   
   
       12 . The ESP of claim  18 , wherein the alignment device comprises an upper housing and a lower housing, each housing having one of the guide profiles, and a spring located between the upper housing and the lower housing urging the upper housing and the lower housing apart. 
   
   
       13 . A method of connecting a live shaft of an ESP pump motor to a driven shaft, the shafts having splined ends, the method comprising:
 providing a guide profile on each splined shaft end;   mounting an alignment element within a splined coupling; and   inserting the splined shaft ends into the coupling and engaging profiles on the alignment element.   
   
   
       14 . The method of  claim 13 , wherein the profile comprises a protrusion and the alignment element comprises a recess configured to receive the protrusion. 
   
   
       15 . The method of  claim 13 , wherein the alignment element comprises a protrusion and the profile comprises a recess configured to receive the protrusion. 
   
   
       16 . The method of  claim 13 , wherein the shaft ends are maintained coaxial within the coupling by engaging the profiles with the alignment element. 
   
   
       17 . The method of  claim 13 , wherein the alignment element comprises a disk member having profiles on its upper and lower surface, the method further comprising mounting the alignment element perpendicularly in the splined coupling.