Subsea Actuator Roller Screw Override Mechanism

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Solution Overview

Problem

Existing subsea valve actuators face challenges in efficiently and reliably operating subsea valves, particularly during maintenance or inspection of wellheads, and lack effective override mechanisms for scenarios where primary drive failure occurs.

Innovation Solution

An actuator with a screw assembly that includes a roller screw and roller nut, featuring an override mechanism allowing axial movement of the screw and nut relative to the housing, enabling operation even in failure scenarios, and utilizing a release mechanism to transition from normal to override mode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a screw assembly with roller screw and roller nut is used for actuator operation, then the conversion of rotational movement to axial movement is efficient and reliable, but the system lacks override capability when primary drive fails

Engineering Contradiction:

Improvereliability of valve operationVSAvoidoverride capability in failure scenarios

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The actuator incorporates a dynamic override mechanism that allows transition from normal locked operation mode to override mode where the screw and roller nut can move axially relative to each other. This dynamic reconfiguration enables the system to adapt to failure scenarios by releasing the normal operational constraint while maintaining the mechanical connection between screw and nut, thus providing both reliable normal operation and fail-safe override capability.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If the screw assembly is fixed to prevent axial movement during normal operation, then operational precision is maintained, but the system cannot respond to override requirements

Engineering Contradiction:

Improveprecision of valve actuationVSAvoidease of override operation

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The actuator separates the screw and roller nut into independently movable segments during override operation. The screw remains rotationally constrained but can move axially relative to the roller nut, which maintains its rotational constraint. This segmentation allows precise control during normal operation while enabling independent axial movement during override, thus maintaining both precision and ease of override operation.

Inventive Principle:

Principle #1Segmentation

3Stability of the object's composition

If the axial stop prevents axial movement of the screw or threaded part, then normal operational stability is ensured, but the actuator cannot be overridden

Engineering Contradiction:

Improvestability during normal operationVSAvoidfail-safe operation capability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The axial stop is designed with a release mechanism that changes its functional parameter from completely preventing axial movement during normal operation to allowing controlled axial movement during override. The stop maintains its positional constraint function during stable operation but can be selectively released to permit the screw or threaded part to move axially, thus ensuring both operational stability and fail-safe reliability.

Inventive Principle:

Principle #35Parameter changes

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

Ensures reliable operation of subsea valves, including during maintenance, and provides a fail-safe mechanism to operate valves even in the event of primary drive failure, ensuring continuous functionality and accessibility.

Implementation Method 1

The screw assembly comprises a roller screw and a roller nut

Methodology Applied

Scientific EffectRolling contact: Roller

Implementation Method 2

The screw assembly is for converting the rotational movement to an axial movement of a valve member relative to the housing

Methodology Applied

Scientific EffectMechanical advantage: Mechanical Advantage

Data Source

PatentEP4172460B1Actuator and associated methods

Publication Date: 2025.06.25 ONESUBSEA AS

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Figure 3~4

AI summary

P288355WO 33 ABSTRACT CONNECTOR AND ASSOCIATED METHODS Actuator for providing a subsea electrical actuation. The actuator has a screw 5 assembly with a screw and a threaded part; and a housing for the screw assembly. An axial stop prevent axial movement relative to the housing of one of the screw and the threaded part in a normal mode of operation. A primary drive provides a rotational movement to the screw assembly in the normal mode of operation. The screw assembly converts the rotational movement to an axial movement of a valve member 10 relative to the housing. An override is provided for operating the actuator in an override mode of operation, the override releasing at least one of the screw and the threaded part for axial movement relative to the housing in the override mode. Figure 115