CENTERING COUPLING FOR ELECTRICAL SUBMERSIBLE PUMP SPLINED SHAFTS
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.
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This application is a continuation-in-part of patent application having Ser. No. 12/125,350, filed May 22, 2008.
FIELD OF THE INVENTIONThis invention relates in general to electrical submersible well pumps, and in particular to couplings between splined shafts of an electrical submersible pump.
BACKGROUND OF THE INVENTIONElectrical submersible pumps (ESP) are commonly used for hydrocarbon well production,
The pumping system 10 includes an electrical submersible pump (ESP) 14 with production tubing 24 attached to its upper end. The ESP 14 comprises a motor 16, an equalizer or seal 18, a separator 20, and a pump 22. A fluid inlet 26 is formed in the housing in the region of the ESP 14 proximate to the separator section 20. The fluid inlet 26 provides a passage for the produced hydrocarbons within the wellbore 5 to enter the ESP 14 and flow to the pump 22. Fluid pressurized by the pump 22 is conveyed through the production tubing 24 connecting the ESP 14 discharge to the wellhead 12. The pump 22 and separator 20 are powered by the motor 16 via a shaft (not shown) that extends from the motor 16. The shaft is typically coupled to respective shafts in each of the pump 22, separator 20, and seal 14.
Delivering the rotational torque generated by an ESP motor 16 typically involves coupling a motor shaft (i.e., a shaft connected to a motor or power source) to one end of a driven shaft, wherein the other end of the driven shaft is connected to and drives rotating machinery. Examples of rotating machinery include a pump, a separator, and tandem pumps. One type of coupling comprises adding splines on the respective ends of the shafts being coupled and inserting an annular collar over the splined ends, where the annular collar includes corresponding splines on its inner surface. The rotational force is well distributed over the splines, thereby reducing some problems of stress concentrations that may occur with keys, pins, or set screws. Examples of a spline cross-section include an involute and a square tooth. Typically, splines having an involute cross-section are smaller than square tooth splines, thereby leaving more of the functional shaft diameter of a shaft to carry a rotational torque load. Additionally, involute spline shapes force the female spline to center its profile on the male spline, thus coaxially aligning the shafts in the coupling with limited vibration. Square tooth splines are made without specialized cutters on an ordinary mill. However square teeth spline couplings do not align like involute teeth unless the clearance is reduced or the male and female fittings are forced together. However, reducing clearance or force fitting square teeth splines prevents ready assembly or disassembly.
SUMMARY OF THE INVENTIONDisclosed herein is a submersible pumping system for pumping wellbore fluid, comprising, a pump motor, a seal section a motor shaft having an end rotatably affixed within an end of a shaft coupling, the motor shaft rotatable by the motor, a driven shaft having an end rotatably affixed within an 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 provided in the shaft coupling, the element coaxially engaging the respective terminal ends of the motor shaft and driven shaft within the shaft coupling. In one embodiment, the element is disposed in bores formed in the respective terminal ends of the motor shaft and driven shaft. The alignment element may comprise a member having a slot or channel axially extending along a portion of the element body axis and bisecting the element body. The bisected element body may be compressibly inserted within a respective bore. An optional second slot or channel axially extends along a portion of the element body axis to bisect the element body. The second slot extends from an end of the body oppositely disposed from the end where the first slot extends. The element body bisected by the second slot may be compressibly inserted within the other respective bore.
Optionally, the alignment element may comprise a tolerance ring coaxially disposed between a shaft and the shaft coupling. A second tolerance ring may be disposed between the other shaft and the shaft coupling. Yet further optionally, a single tolerance ring may extend between within the shaft coupling along a portion of both the motor shaft and the driven shaft.
Also disclosed herein is a method of using an electrical submersible pump (ESP) in a wellbore involving providing the ESP in the wellbore. The ESP may include a motor, a motor shaft rotatingly affixed to the motor; a rotating device, a driven shaft rotatingly affixed to the rotating device, and a coupling rotatingly affixing ends of the motor shaft and driven shaft. The method may further include energizing the motor, thereby rotating the motor shaft, the coupling, and the driven shaft. Additionally, the present method includes substantially coaxially aligning the ends of the motor shaft and driven shaft during shaft rotation. The method optionally further comprises providing a compressible alignment element in the coupling between the shaft ends, and coaxially mating the shaft ends with the alignment element. The compressible alignment element may comprise a member having a slot or channel axially extending along a portion of the element body axis and bisecting the element body. Optionally, the compressible alignment element may comprise a tolerance ring.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. For the convenience in referring to the accompanying figures, directional terms are used for reference and illustration only. For example, the directional terms such as “upper”, “lower”, “above”, “below”, and the like are being used to illustrate a relational location.
It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.
The present disclosure includes a square tooth spline coupling with vibration control. The coupling disclosed herein provides sufficient clearance between the respective male and female splines providing ready assembly and disassembly. With reference now to
The coupling assembly 30 of
Centering guides (62, 63) are shown extending from the upper and lower surface of the alignment element 54. In this embodiment, the centering guides (62, 63) comprise conically shaped protusions. Above and below the coupling assembly 30 are an upper shaft 32 and lower shaft 40. The upper shaft 32 lower end 36 is provided with male splines 34 configured for coupling engagement with the female splines 52 of the coupling assembly 30. Similarly, the lower shaft 40 upper end 44 includes male splines 42 configured for coupling engagement with the female splines 52. The shafts (32, 40) are profiled on their terminal ends for centering engagement with the centering guides (62, 63) of the alignment element 54. In the embodiment shown, the profiling on the shafts comprises recesses or bores (38, 46) extending from the terminal mating tips of the shafts and substantially aligned with the respective axes (ASH, ASL) of the upper or counterbore lower shafts (32, 40). Each recess (38, 46) has a conical entry way with a taper matching the centering guides (62, 63). The recess and protrusion provide examples of guide profiles formed on the shaft ends and alignment element for engaging the shaft ends to the alignment element. During pumping operations, impellers in the pump create an axial thrust force in the pump shaft forcing the shafts (32, 40) together and engaging the centering guides (62, 63) with the recesses (38, 46).
Referring now to
Yet another embodiment of a shaft coupling 30b is provided in side cross-sectional view in
As shown in
Another embodiment illustrating ESP shaft coupling is provided in a side partial cut-away view in
A coupling assembly is presented in side partial cross sectional view in
An example of an alternative shaft coupling is provided in
With reference now to
Another optional compressive alignment element is illustrated in
The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims. While the invention has been shown in only one of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes without departing from the scope of the invention.
Claims
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.
Type: Application
Filed: Dec 11, 2008
Publication Date: Nov 26, 2009
Applicant: BAKER HUGHES INCORPORATED (Houston, TX)
Inventors: David Neuroth (Claremore, OK), Terry Shafer (Broken Arrow, OK)
Application Number: 12/332,717
International Classification: F04B 35/04 (20060101);