Subsea Linear Motor Actuator for Valve Control
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Solution Overview
Problem
Existing subsea wellhead systems face challenges in efficiently and reliably controlling fluid flow due to the limitations of traditional valve mechanisms, which can be cumbersome and prone to failure in the harsh underwater environment.
Innovation Solution
A linear motor actuator system is introduced, comprising magnetized segments and a winding array that uses alternating current to move a gate valve, with a fail-safe mechanism involving a spring and plunger to ensure reliable operation even in power loss scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional valve mechanisms are used in subsea wellhead systems, then the structure is simple and easy to manufacture, but the reliability is poor and they are prone to failure in harsh underwater environments
Solution Approach 1:
The patent replaces traditional mechanical actuation mechanisms with a linear motor system that uses electromagnetic fields to directly drive the valve gate. The linear motor comprises a motor shaft with alternating polarity magnetized segments and a stator with windings, eliminating complex mechanical linkages, gears, and linkages that are prone to failure in subsea environments. This substitution of mechanical systems with electromagnetic systems directly addresses the reliability issue while accepting increased device complexity.
2Ease of operation
If traditional sliding stem-type valves are used, then the manufacturing is simple, but the operation is cumbersome and less precise in controlling fluid flow
Solution Approach 1:
The linear motor system replaces cumbersome manual or mechanical operation with electrically controlled electromagnetic actuation. The multi-phase electrical supply sequentially energizes stator windings to create a moving magnetic field that precisely controls the linear motion of the motor shaft and connected valve gate. This provides smooth, precise, and easily controllable valve operation while increasing actuator structure complexity.
Solution Approach 2:
The linear motor system enables dynamic control of the valve gate position through variable frequency and amplitude control of the electrical supply. The motor can be precisely positioned at any point along its stroke, allowing for throttling and precise flow control rather than just full open/closed positions. This dynamic control capability improves ease of operation while requiring a more complex actuator structure.
3Measurement precision
If linear motor actuator system is implemented, then the control precision and reliability are improved, but the device complexity increases
Solution Approach 1:
The electromagnetic linear motor system provides precise control of the valve gate position through electronic control of the multi-phase electrical supply. The alternating polarity magnetized segments on the motor shaft interact with the stator magnetic field to achieve precise linear positioning. This electromagnetic control system delivers superior position precision compared to mechanical systems while accepting the inherent complexity of the linear motor structure.
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 system provides precise and reliable control of fluid flow, ensuring safe and efficient operation of subsea wellhead systems by leveraging magnetic fields and alternating current to move the valve gate, while the fail-safe mechanism ensures continued functionality in case of power loss.
Implementation Method 1
flowing electrical current through the winding array applies a magnetic field to linearly move the magnetized segments and cause the gate to move relative to the winding array
Implementation Method 2
A resilient member, such as a spring, can be engaged with the magnetized segments, so that movement of the magnetized segments from a first position compresses the resilient member and when the magnetic field is removed, the resilient member expands and moves the magnetized segments and gate back to the first position
Data Source
AI summary
An actuator for use with valves in a subsea wellhead assembly. The actuator includes a shaft with an alternating polarity along its length and windings spaced around the shaft that create a magnetic field around the shaft. The shaft is connectable to a valve stem so that flowing current through the windings creates a magnetic field for linearly moving the shaft and operating the valve. A fail safe mechanism can be included that pushes the shaft back to its original position thereby also moving the valve into its original, or fail safe, position.