Weak Link Latch Rotatable Arm Shear Pin Conduit
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Solution Overview
Problem
Existing methods for pulling offshore cables, such as those between wind turbines, often require multiple pulling lines, increasing costs, complexity, and the risk of failure, particularly due to uneven terrain and directional pulling forces that can prematurely break conduit leaders in weak link arrangements.
Innovation Solution
A weak link latch with an elongated central member and rotatable arms that engage with a conduit and cable, using a shear pin to allow differential pulling forces, preventing premature breakage by locking in one direction and disengaging in the opposite, ensuring the cable can be pulled efficiently and safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pull line with weak link arrangement is used to pull both conduit and cable, then cost and complexity are reduced, but the conduit leader breaks prematurely due to bidirectional pulling forces
Solution Approach 1:
The locking arm is designed to be rotatable about an axis, transitioning between locked and unlocked positions based on the direction of pulling force. When force is applied in the intended direction, the arm rotates to lock position; when force reverses, it rotates to unlocked position, allowing the shear pin to break safely without damaging the conduit leader.
Solution Approach 2:
The locking arm acts as an intermediary mechanism between the pull line and the conduit leader. It transmits force in the intended direction while blocking reverse force transmission, protecting the conduit leader from bidirectional stress that would cause premature failure.
2Reliability
If wire leaders are over dimensioned to prevent premature breakage, then reliability improves, but cost and complexity increase
Solution Approach 1:
The system segments the force transmission path into two distinct pathways: one through the locking arm and shear pin for the conduit, and another through the connection line for the cable. This allows each component to be optimized for its specific function rather than over-dimensioning all components for maximum bidirectional strength.
3Productivity
If the rotatable arm is held in locked position by a shear pin, then the single pull line can pull both objects efficiently, but the shear pin must break under controlled conditions
Solution Approach 1:
The shear pin is designed with specific material properties and geometric dimensions that define its breaking strength. The locking arm's geometry and the applied force angle create a moment that exceeds the shear pin's strength threshold when the conduit contacts resistance, causing controlled breakage at a predetermined force level.
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 allows for efficient and cost-effective pulling of cables by using a single pull line, reducing the risk of failure and complexity, while preventing premature breakage of conduit leaders, even in deep sea environments with varying terrain.
Implementation Method 1
A shear pin having a predetermined breaking strength holds the rotatable arm in the extended lock position... the pull line may then be pulled with increasing force until the shear pin breaks
Implementation Method 2
the shear pin breaks, which allows the rotatable arm to rotate to the collapsed release position whereby the arms disengage from the first object
Data Source
AI summary
A weak-link latch for releasably pulling a cable (13) arranged in a conduit (14). The weak link latch is releasably connected to the conduit, and securely connected to the cable. A plurality of arms (4,5) extend laterally from a central member (1) arranged to engage the conduit, with at least one of which arms being a rotatable arm (5,19), rotatable about an axle (6) from an extended position in locked engagement with the conduit to a collapsed position disengaged from the conduit. A shear pin (7) is arranged between the rotatable arm (5,19) and the central member (1), the shear pin arranged to prevent rotation of the rotatable arm from the extended position to the collapsed position, said shear pin having a predetermined breaking force, said breaking force being a shear force due to rotational force from the rotatable arm.