Spring-Locked Shaft Coupling for Bi-Directional ESP Loads
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Solution Overview
Problem
Existing electric submersible pump (ESP) systems face challenges in efficiently managing bi-directional loading on inner shafts, requiring additional thrust bearings to isolate compressive and tensile forces, which complicates assembly and increases costs.
Innovation Solution
A locking coupling assembly with a shaft locking mechanism that transfers tensile and compressive forces, using locking keys and a plunger assembly to maintain axial distance between shafts, eliminating the need for separate thrust bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If typical couplings are used for inner shafts, then compressive loading can be transmitted, but tensile loading cannot be transmitted
Solution Approach 1:
The coupling employs a dynamic locking mechanism where plungers move axially between retracted and extended positions. During assembly, plungers are retracted to allow shaft insertion; during operation, plungers extend to engage grooves and lock the shafts together, enabling tensile load transmission while maintaining structural simplicity
Solution Approach 2:
The coupling changes the engagement state parameter of the plungers (retracted vs. extended) to switch between assembly mode and operational mode. This parameter change enables the same structure to serve dual purposes: simple assembly without rotation requirement, and secure locked connection for tensile loading
2Reliability
If additional thrust bearings are added to counteract tensile loading, then bi-directional loading can be managed, but system complexity and cost increase
Solution Approach 1:
The invention merges the functions of thrust bearing (for compressive loading) and tensile load counteraction into a single coupling assembly. The coupling handles both compression transmission and tensile load management through its locking mechanism, eliminating the need for separate thrust bearings and reducing overall system complexity
Solution Approach 2:
The coupling assembly performs multiple functions: transmitting compressive loading, counteracting tensile loading, and providing mechanical connection between shafts. This multi-functional design replaces what would traditionally require separate specialized components for each function, thereby reducing the total number of components
3Ease of manufacture
If sections are coupled by axially moving into contact, then assembly is simplified, but tensile loading cannot be transferred
Solution Approach 1:
The coupling employs preliminary action by retracting the plungers before shaft insertion during assembly, allowing easy axial coupling without rotation. After assembly, the plungers are extended to engage the grooves, transforming the loose axial connection into a locked connection capable of tensile load transfer
Solution Approach 2:
The coupling transitions from a static axial contact design to a dynamic design where plungers can move between retracted and extended states. This dynamic capability allows the same structure to provide both easy assembly (retracted state) and tensile load transfer (extended state)
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The locking coupling assembly effectively manages bi-directional loading on inner shafts, simplifying assembly and reducing costs by integrating tensile and compressive force transfer without additional thrust bearings.
Implementation Method 1
a plunger spring positioned within the plunger bore and configured to apply an elastic force to the plunger
Data Source
AI summary
An electrical submersible pump assembly comprising a first section and a second section with an outer housing and a drive shaft. A coupling assembly comprising a coupling, a first and a second locking keys, and a plunger assembly mechanically couples the first drive shaft to the second drive shaft. The coupling is cylindrical in shape with splines configured to transfer torque from the first drive shaft to the second drive shaft. The plunger assembly extends the first and second set of locking keys from a key port in the first shaft and second shaft into a groove within the coupling. The coupling assembly is configured to transfer tensile stress from the first drive shaft to the second drive shaft in response to extending the first locking key in the first groove and the second locking key in the second groove of the coupling.