Boss Lip Design for Composite Pressure Container Sealing
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Solution Overview
Problem
Composite pressure containers face challenges with O-rings swelling due to fluid contact, leading to potential leakage and reduced durability, especially at high pressures, and existing solutions are costly and not adaptable to varying pressure conditions.
Innovation Solution
A boss design for composite pressure containers featuring a lip with adjustable radial thickness and Shore A hardness of O-rings, optimized for specific test pressures, which includes an embedded member and mounting means to reduce O-ring swelling influence and enhance sealing, using materials like thermoplastic and fibre-reinforcement for durability and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If O-rings are used to seal the passage between boss and coupling/valve member, then sealing is achieved, but O-rings swell when in contact with fluid causing indentations and potential leakage
Solution Approach 1:
The patent introduces an intermediary component (the lip with specific hardness and geometry) between the O-ring and the boss structure. This lip acts as a mediator that distributes the O-ring swelling forces over a larger area, preventing direct transmission of swelling-induced indentations to the sealing surface, thereby maintaining sealing reliability while accommodating O-ring dimensional changes
Solution Approach 2:
The patent changes the physical parameters of the boss structure by introducing a lip with specific hardness (Shore A 40-70) and geometric parameters (radial thickness, height). These parameter changes allow the structure to be sufficiently compliant to absorb O-ring swelling while maintaining sufficient rigidity to prevent indentation and leakage, thus resolving the contradiction between sealing reliability and dimensional stability
2Stress or pressure
If boss construction is designed to withstand high pressures, then pressure resistance is improved, but cost and complexity increase
Solution Approach 1:
The patent applies local quality by concentrating the pressure resistance function in specific localized features of the boss (the lip with optimized hardness and geometry, and the reinforced aperture region) rather than requiring the entire boss structure to be overly complex or expensive. This allows high pressure resistance with controlled complexity
Solution Approach 2:
The patent employs composite construction by combining materials with different properties - the boss is made from material with Shore A hardness 40-70 that provides both compliance for sealing and rigidity for pressure resistance, potentially combined with fibre-reinforced materials in the pressure container structure to achieve high pressure resistance without excessive complexity
3Reliability
If O-ring swelling is allowed to occur, then sealing initial contact is achieved, but indentations form on sealing surfaces reducing durability
Solution Approach 1:
The patent implements beforehand cushioning by designing the lip structure with specific compliance characteristics (Shore A hardness 40-70) that anticipate and absorb the O-ring swelling forces before they can cause damaging indentations. The lip acts as a pre-designed cushioning element that protects the sealing surface from the harmful effects of O-ring expansion, maintaining both initial sealing contact and long-term durability
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 boss design provides a durable, cost-effective sealing solution that reduces O-ring swelling effects, ensuring a gas-tight seal across various pressure ranges, allowing for multiple uses and reducing production costs by adapting to different pressure conditions.
Implementation Method 1
The O-rings under the prevailing conditions within a boss have a tendency to swell when in contact with the fluid
Implementation Method 2
The inner pressure will influence the boss with an axially outward directed force which may be considerable
Implementation Method 3
The radial thickness of the lip is proportional with the test pressure for which the container is intended
Data Source
AI summary
A boss (1) for a composite pressure container for fluids, in which the radial thickness of a lip (23) of the boss arranged between the coupling or valve member (5) and an embedded member (2) is especially adapted to the intended pressure inside the container.