Dual Roller-Screw Actuator for High-Force Subsea Rod Drive
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Solution Overview
Problem
Existing hydraulic power actuators used in subsea applications, such as blow-out preventers, face challenges with large size, weight, and pressure drop issues, necessitating the development of electro-mechanical actuators that require accurate load distribution and manual override mechanisms.
Innovation Solution
An actuator design featuring two rotatably arranged roller screws with separate actuation elements connected via spherical thrust bearings, allowing for independent rotation and axial displacement of roller nuts, which are coupled to a rod for engaging well barriers or cutting devices, utilizing electric motors and gear systems for efficient force generation and load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If hydraulic systems are used for power actuation in subsea applications, then large actuation forces can be generated, but the system becomes large and heavy requiring hydraulic communication to surface
Solution Approach 1:
The patent replaces the hydraulic system with an electro-mechanical system using roller screws and roller nuts. Electric motors drive the roller screws, which convert rotational motion to linear motion through the roller nut mechanism, eliminating the need for hydraulic fluid and associated heavy infrastructure while maintaining the ability to generate large actuation forces
2Device complexity
If electro-mechanical actuators with common actuation elements are used, then system complexity is reduced, but bending moments are induced in the screws and actuation element
Solution Approach 1:
The patent divides the actuation system into separate independent actuation elements, each connected to its own roller nut. This segmentation prevents bending moments from being transferred between elements, as each actuation element operates independently. The roller screws are also separated into individual units rather than a common shared element
3Stress or pressure
If hydraulic fluid is vented to sea in subsea applications, then pressure drop in return lines is avoided, but environmental contamination occurs
Solution Approach 1:
The electro-mechanical actuation system eliminates hydraulic fluid entirely, replacing it with electric motors and mechanical transmission elements. This substitution removes the source of fluid discharge and environmental contamination while maintaining the necessary pressure and force generation capabilities through electrical and mechanical means
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 solution provides a compact, efficient, and reliable means to generate large axial forces, preventing bending moments and eliminating hydraulic fluid discharge, with the ability to operate manually in case of power failure, suitable for subsea applications requiring high actuation forces.
Implementation Method 1
rotation of roller screws results in parallel, axial displacement of roller-nuts comprising thread-rolls engaging threads on the screws
Implementation Method 2
Each roller-nut is arranged with an actuation element prevented from rotating and connected to the roller-nut with a spherical thrust bearing
Data Source
AI summary
An actuator is for use in petroleum exploitation and is configured for displacing a rod for engaging a well barrier device. The actuator has a housing for at least a portion of the rod; at least two roller screws rotatably arranged in the housing; rotational means connected to the roller screws via one gear systems for each roller screw for simultaneous rotation of the roller screws; and a roller nut engaging each roller screw. The roller screws and roller nuts are configured such that rotation of the roller screws result in displacement of the roller nuts relative to the roller screws. Each roller nut is coupled with one actuation element via spherical bearings, and each actuation element is configured for mechanical coupling to an end portion of the rod for displacing the rod in operational use.