Cable Strand Universal Joint for Drilling Abrasion
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Solution Overview
Problem
Conventional universal joints in downhole drilling operations are prone to abrasion and erosion due to extreme torque forces and abrasive drilling fluids, leading to reduced operational life and increased maintenance costs, as they require frequent replacement and are difficult to seal effectively.
Innovation Solution
A universal joint design featuring elongate links and flexible cables with multiple strands, which are less susceptible to fretting and spalling, and include a service life indicator to monitor wear and fatigue, allowing for early replacement and minimizing downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional universal joints with bearing surfaces are used, then torque transmission is achieved, but abrasion and erosion occur due to sliding or rotating contact surfaces in abrasive drilling fluids
Solution Approach 1:
The patent replaces conventional bearing surfaces with cable strands that transmit torque through tension and compression rather than sliding or rotating contact. The cable strands are subjected to axial forces along their length, eliminating the sliding contact that causes abrasion and erosion in traditional universal joints.
Solution Approach 2:
The patent changes the fundamental parameter of force transmission from lateral sliding/contact forces to axial tension/compression forces in the cable strands. This parameter change transforms the stress state from shear and contact stress to primarily axial stress, which the cable strands are optimized to withstand.
2Reliability
If conventional sealing arrangements are implemented, then attempts are made to protect components, but constant relative movement and aggressive downhole environment lead to sealing failures
Solution Approach 1:
The patent extracts and eliminates the sealing system entirely by removing the vulnerable bearing surfaces that required sealing. The cable strand universal joint design inherently resists abrasion without requiring seals, simplifying the overall structure and eliminating sealing failure modes.
3Reliability
If drill string components are replaced frequently, then operational life is extended, but removal of drill string and downtime increase operational expenses
Solution Approach 1:
The patent inverts this principle by creating a durable, long-lasting universal joint using cable strands that resist wear and erosion. The extended service life of the cable strand universal joint reduces the frequency of replacements, thereby reducing downtime and operational expenses despite the initial cost of the component.
4Volume of moving object
If compact assembly is achieved, then drill string length is shortened, but space constraints limit design options
Solution Approach 1:
The patent segments the torque transmission function into multiple cable strands arranged radially around the central axis. This segmentation allows the universal joint to be compact while maintaining structural integrity and torque capacity, as the distributed cable strands efficiently transmit forces without requiring large individual component dimensions.
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 universal joint provides extended service life with reduced susceptibility to erosion and wear, allowing for efficient torque transmission and axial rotation conversion while maintaining a compact assembly, thus reducing operational expenses and extending drill string component life.
Implementation Method 1
The links are elongate with opposite ends received by the member around their circumferences. The universal joint accommodates misalignment of shafts connected to the members and transfers torque from one shaft to the other.
Data Source
AI summary
A universal joint assembled to a drill string transfers torque and axial force between two components along a longitudinal axis where the shafts of the components are not completely aligned. The universal joint includes axially spaced members joined by transversely spaced links. As the joint rotates the links move to accommodate misalignment between the drill string components and the connected members.