Compression Fitting Visual Torque Indication for Leak Prevention
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Solution Overview
Problem
Compression fittings, such as B-nuts, used in aircraft to connect tubing to threaded fittings lack a visual indication of torque status, leading to potential leaks during pressurized fluid tests and difficulties in ensuring the fittings remain torqued.
Innovation Solution
A tubing nut fastener design featuring two partially rotatable elements with engagement members and permanent visual indicators that change spatially with torque, allowing for easy visual determination of the torqued state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a traditional B-nut compression fitting is used, then the connection between tubing and threaded fitting is achieved, but there is no visual indication of torque status
Solution Approach 1:
The B-nut is divided into two separate elements: a main body and a rotating nut portion. This segmentation allows the nut portion to rotate relative to the main body during torquing, enabling visual indicators to change position and provide torque status information without requiring a completely new fitting design.
Solution Approach 2:
Visual indicators (marks or features) are introduced as intermediary elements between the rotating nut and the stationary main body. These indicators serve as mediators that translate the mechanical rotation into visible information, allowing operators to determine torque status without complex sensing systems.
2Ease of operation
If tubing is installed, loosened, and adjusted during aircraft manufacturing, then fit requirements are achieved, but it becomes difficult to determine if the B-nut has been torqued
Solution Approach 1:
The visual indicators provide immediate feedback about the torque status of the B-nut. After adjustment and torquing operations, the position of the visual indicators clearly indicates whether the fitting is properly torqued, eliminating the information loss that occurs with traditional fittings during manufacturing operations.
3Difficulty of detecting and measuring
If visual indication of torque status is added to the B-nut, then torque verification becomes possible, but the device complexity increases
Solution Approach 1:
The patent employs visual indicators that may utilize color changes or different visual characteristics to indicate torque status. This approach provides clear detection capability through simple visual observation rather than requiring complex measurement instruments, balancing detectability with device simplicity.
Data Source
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AI summary
A tubing nut fastener is described that includes two separate elements that are partially rotatable with respect to each other. In between the rotatable elements, engagement members (e.g., balls) are captured within interior channels. Both of the partially rotatable elements include a permanent marking or other non-removable visual indicator, which varies spatially depending on whether the tubing nut fastener is in a torqued state or an un-torqued state, thereby providing a simple visual indication of the status of the tubing nut fastener.