Pressure Vessel Boss Assembly Sealing Composite Shells
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Solution Overview
Problem
Non-metallic pressure vessels face challenges in securely attaching the boss to the outer shell and liner, leading to potential leak paths due to various load cases such as rotational forces, vacuum pressure, and pressure buildup, which can result in fluid leakage over time.
Innovation Solution
The boss assembly features a cover end with fastener bores, a transitional portion with notches, and a filling bore defined by a curvilinear surface, along with a boss cover and O-rings, which provides a secure sealing mechanism by engaging fasteners and O-rings to prevent fluid leakage, utilizing a lightweight material like aluminum or composites for the boss and boss cover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If non-metallic pressure vessels are used to reduce weight, then the weight of the pressure vessel is reduced, but the ability to securely attach the boss to the outer shell and liner deteriorates
Solution Approach 1:
The boss is constructed using composite materials, specifically a metallic boss core surrounded by a non-metallic boss cover (such as polymer or composite material), allowing the structure to simultaneously achieve lightweight properties and high attachment strength. The metallic core provides structural integrity and secure attachment capability, while the non-metallic cover reduces overall weight and matches the outer shell material properties.
2Reliability
If the boss is securely attached to prevent leakage, then the sealing reliability is improved, but the device complexity increases
Solution Approach 1:
The boss assembly is segmented into distinct functional components: a metallic boss core for structural attachment, a non-metallic boss cover for sealing and weight reduction, and integrated sealing elements (O-rings, gaskets). This segmentation allows each component to be optimized for its specific function while simplifying the overall assembly process through modular construction.
Solution Approach 2:
The boss cover is designed to fit over and enclose the boss core, creating a nested structure where the metallic core is embedded within the non-metallic cover. This nested configuration provides secure attachment capabilities from the core while the outer cover provides sealing and protects the interface, achieving high reliability without complex external fastening systems.
3Reliability
If the boss assembly uses multiple fasteners and sealing elements, then the sealing integrity is improved, but the manufacturing complexity increases
Solution Approach 1:
Multiple sealing functions are merged into integrated sealing elements that are built into the boss assembly structure. For example, O-rings are embedded in grooves within the boss or boss cover, and gaskets are integrated into the flange structure. This merging eliminates the need for separate sealing components and simplifies assembly, as the sealing function is inherent to the structural components rather than being added separately.
Data Source
AI summary
This invention relates to a boss assembly that seals a pressure vessel and more particularly to sealing a pressure vessel having a composite outer shell for use with a source of compressed gas having a boss and boss cover in sealing engagement. The composite outer shell is wound about the boss and locked into at least one notch and/or a reverse draft cut. The boss cover is removably fastened to the boss utilizing at least one fastener. The principle use is for storage and usage of compressed gas in mobile applications that typically benefit from light weight pressure vessels however other applications will benefit from this invention. For example, applications that routinely fill and/or un-fill containers made of woven, composite, and etc. materials will benefit from this invention.