Subsea Torque Limiter With Self-Resetting Ball Detent Mechanism
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Solution Overview
Problem
Subsea valves are prone to failure due to over-torque from ROV torque tools, and existing torque limiters using shear pins often fail inadvertently, leading to costly downtime in subsea operations.
Innovation Solution
A subsea torque limiter featuring a ball detent mechanism with a biasing member that maintains engagement at low torque levels and decouples the input and output shafts when a predetermined torque is reached, allowing for automatic re-engagement once the torque drops below the limit, ensuring bi-directional operation and reducing the need for manual resetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shear pins are used to protect valve stems from over torque, then the valve stems are protected from failing, but the shear pins sometimes fail inadvertently and require retrieval to replace them
Solution Approach 1:
The torque limiter automatically resets itself after an over-torque event by allowing the ball detent mechanism to re-engage when torque drops below the threshold, eliminating the need for manual retrieval and replacement of components
Solution Approach 2:
The patent replaces the disposable shear pin concept with a reusable ball detent mechanism that can cycle through engagement and disengagement multiple times without replacement, significantly reducing operational costs and downtime
2Force
If shear pins are used to limit torque, then the torque can be limited to a predetermined level, but retrieving the torque limiter to replace the shear pins leads to expensive downtime
Solution Approach 1:
The system performs self-resetting automatically after torque events, maintaining continuous operation and eliminating productivity loss associated with manual intervention
Solution Approach 2:
The ball detent mechanism dynamically transitions between engaged and disengaged states based on torque levels, allowing automatic recovery and continuous operation without manual resetting
3Loss of time
If a ball detent mechanism is used instead of shear pins, then automatic re-engagement is possible reducing downtime, but the mechanism must maintain axial immobility of shafts during transitions
Solution Approach 1:
The mechanism is divided into distinct functional components (ball members, detent ring, biasing member) that work independently but coordinate together to achieve automatic resetting while maintaining shaft stability
Solution Approach 2:
The biasing member acts as an intermediary that maintains axial force on the ball members, ensuring axial immobility of the shafts while allowing the ball detent mechanism to transition between states for automatic resetting
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 torque limiter effectively protects subsea valves from over-torque damage, allows seamless operation resumption without manual intervention, and maintains axial immobility of input and output shafts during transitions, reducing downtime and operational costs.
Implementation Method 1
a biasing member which is designed to generate a force sufficient to maintain the ball detent mechanism in the engaged condition when a torque less than a predetermined torque is applied to the input shaft
Data Source
AI summary
A torque limiter includes a housing; an input shaft which is rotatably supported in the housing; an output shaft which is rotatably supported in the housing coaxially with the input shaft; and a ball detent mechanism which is connected between adjacent ends of the input and output shafts. The ball detent mechanism includes a ball ring and has a plurality of ball members; a detent ring which is connected to the input shaft and has a plurality of detents which are configured to receive the ball members; and a biasing member which is positioned on a side of the ball ring opposite the detent ring. The biasing member is operatively engaged with the ball members so as to bias the ball members in a direction toward the detent ring and is designed to generate a force sufficient to maintain the ball members seated in the detents when a torque less than a predetermined torque is applied to the input shaft.