Flared Tube End Joint for Leak-Free High-Pressure Hydrogen Filling
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Solution Overview
Problem
Existing high-pressure hydrogen fuel system fittings struggle to provide a secure and leak-free connection, especially in hydrogen-powered vehicles where small leaks can be detrimental due to the high pressure and reactivity of hydrogen.
Innovation Solution
A flared tube end joint fitting is introduced, which includes a male tube with a flared end and a sleeve pressed on during flare forming, along with a threaded hex nut and a female mating port with an internally threaded interface. This configuration establishes a sealed connection by rotating the hex nut to interengage its exterior threads with the female port's interior threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cone and thread fittings are used in hydrogen applications, then the device complexity is reduced, but the reliability and leak-free performance deteriorate due to inability to meet heightened performance demands
Solution Approach 1:
The fitting is divided into distinct functional segments: a tube section with external flare, a separate flare nut with internal threading and sealing surface, and a gasket component. This segmentation allows each component to be optimized for its specific function while maintaining overall reliability and enabling modular assembly that addresses hydrogen leakage concerns.
Solution Approach 2:
A gasket is introduced as an intermediary sealing element between the tube flare and the flare nut sealing surface. This intermediary component ensures a reliable leak-free barrier against hydrogen gas, resolving the contradiction by providing enhanced sealing without requiring the tube and nut materials themselves to be perfectly sealed.
2Reliability
If specialized flare fitting designs are implemented to meet high performance demands, then the reliability improves, but the ease of manufacture deteriorates due to specialized production requirements
Solution Approach 1:
The tube end is pre-flared to a specific angle and geometry before assembly with the flare nut. This preliminary forming of the flare geometry ensures that the sealing surfaces are properly prepared in advance, allowing for reliable connection performance while simplifying the final assembly process and maintaining manufacturability through standardized pre-processing steps.
3Reliability
If a flared tube end joint fitting is used to ensure leak-free connection, then the reliability improves, but the device complexity increases due to additional components such as sleeve, flare nut, and gasket
Solution Approach 1:
The flare nut integrates multiple functions into a single component: it provides the internal threading for securing the tube, contains the sealing surface that interfaces with the tube flare, and incorporates the gasket retention feature. This merging of functions reduces the number of separate parts while maintaining the leak-free hydrogen seal integrity through coordinated design of these integrated features.
Data Source
AI summary
A leak proof mid-line connection assembly including a female tube having a first flared end profile and a male tube having a second flared end profile capturing a sleeve which is supported upon the male tube. A threaded hex nut is supported over the male tube in contact with the sleeve. A female port includes a flare nut having an interiorly threaded interface. Upon successive insertion of the female tube and male tube into the female port, the hex nut is displaced forwardly into contact with the sleeve, with exterior threads of the hex nut rotatably interengaging with opposing interior threads configured upon the female flare nut in order to establish a sealed connection between a mating interface established between the flared end profiles.