Rotodynamically isolated magnetic coupling for downhole reliability
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Solution Overview
Problem
Rotating equipment in downhole environments faces premature failure due to corrosive fluids, high pressures, and debris, which traditional shaft seals cannot effectively mitigate, leading to frequent seal failures and equipment degradation.
Innovation Solution
A magnetic coupling assembly is used to transmit torque without a solid shaft, employing inner and outer barrels with separate bearing assemblies and fluidic isolation to prevent exposure to corrosive fluids, utilizing magnetic bearings and permanent magnets for rotation and support, thereby eliminating the need for traditional shaft seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional shaft seals are used to isolate downhole fluids from rotating equipment, then the equipment can be protected from corrosive fluids, but the seals eventually fail under pressure, temperature, and corrosive conditions leading to fluid ingress and equipment failure
Solution Approach 1:
The patent replaces the mechanical shaft seal system with a magnetic coupling system that uses magnetic fields to transmit torque without mechanical contact. The magnetic coupling consists of magnetized regions on the shaft that interact with corresponding magnetized regions in the housing, creating a contactless torque transmission mechanism that eliminates seal failures and fluid ingress problems
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the rotating shaft and the stationary housing to transmit torque. The magnetic coupling creates a magnetic bridge that allows power transmission without physical contact, serving as a mediator that eliminates the need for mechanical seals while maintaining torque transmission functionality
2Reliability
If shaft seals are eliminated and magnetic coupling is used to transmit torque without mechanical contact, then seal failures are eliminated, but the device complexity increases due to the need for magnetic coupling components
Solution Approach 1:
The patent merges the magnetic coupling components directly into the existing shaft and housing structures. The magnetized regions are integrated into the shaft and housing components rather than being separate add-on parts, combining the torque transmission function with the structural components to minimize additional complexity
Solution Approach 2:
The magnetic coupling system serves multiple functions: it transmits torque without mechanical contact, provides fluid sealing through the contactless interface, and reduces wear on moving parts. This multi-functionality compensates for the added complexity by delivering multiple benefits from a single system
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
This solution enhances the reliability and longevity of downhole rotating equipment by preventing fluid ingress and reducing mechanical contact failures, maintaining efficiency and stability even in harsh environments.
Implementation Method 1
The outer barrel is magnetically coupled to the inner barrel to co-rotate with the inner barrel
Implementation Method 2
utilizing magnetic bearings and permanent magnets for rotation and support
Data Source
Figure 1
Figure 2
AI summary
An inner barrel shaft (118) is separate from the shaft of the first rotating machine (114). A first bearing assembly (116) is configured to support the inner barrel shaft (118). The first bearing assembly (116) is separate from the first rotating machine (114). An outer barrel (108a) includes an outer barrel shaft (106) that is separate from a shaft (124) of a second rotating machine (102). The outer barrel (108a) is configured to be coupled to the shaft (124) of the second rotating machine (102). The second rotating machine is configured to drive or be driven by the first rotating machine. The outer barrel is fluidically isolated from the inner barrel. The outer barrel is configured to surround the inner barrel. The outer barrel is magnetically coupled to the inner barrel to co-rotate with the inner barrel. A second bearing assembly (104) is configured to support the outer barrel shaft. The second bearing assembly is separate from the second rotating machine (102).