Boss Assembly for Composite Cylinder Sealing
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Solution Overview
Problem
The connections between thermoplastic liners and metal parts in composite pressure vessels, particularly type IV cylinders, are weak points that can lead to leakage and inefficiencies in sealing, especially under high pressure.
Innovation Solution
A metal boss is integrated with a thermoplastic liner using a molding process, and a bushing with a deformable relief space region is coupled to the metal boss, allowing for a reduction in distance between the boss and the liner, creating a secure seal through deformation, which is enhanced by an O-ring and a tool system for tightening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a metal boss is directly connected to a thermoplastic liner in a composite cylinder, then the structural simplicity is maintained, but the sealing reliability deteriorates under high pressure
Solution Approach 1:
The connection structure is divided into multiple components: a metal boss integrated with the thermoplastic liner, a separate bushing component with deformable relief space region, and an O-ring seal. This segmentation allows each component to perform its specific function optimally while collectively providing reliable sealing under high pressure.
Solution Approach 2:
The bushing with the deformable relief space region acts as an intermediary element between the metal boss and the thermoplastic liner. This intermediate structure provides a compliant interface that adapts to pressure changes and maintains sealing integrity, preventing direct stress concentration at the boss-liner interface.
2Reliability
If the distance between the metal boss and thermoplastic liner is reduced to improve sealing, then the sealing effectiveness is improved, but the stress concentration increases
Solution Approach 1:
The relief space region of the bushing is designed to be deformable, allowing it to change its shape and volume in response to internal pressure. This parameter change enables the structure to reduce the distance between the boss and liner for effective sealing while simultaneously distributing stresses to prevent concentration and failure.
Solution Approach 2:
The deformable relief space region functions as a flexible element that can elastically deform under pressure. This flexibility allows the structure to adapt to pressure changes, maintaining contact for sealing while absorbing stress through deformation rather than rigid constraint.
3Reliability
If a deformable relief space region is added to the bushing to improve sealing, then the sealing reliability is improved, but the manufacturing complexity increases
Solution Approach 1:
The deformable relief space region is designed with specific geometric parameters that allow it to be formed using conventional molding or machining processes. By optimizing the initial geometry of the relief space, the desired deformable behavior is achieved without requiring complex multi-step manufacturing procedures.
Solution Approach 2:
The bushing is made from materials that combine rigidity for structural support with sufficient elasticity for the relief space deformation. This material selection enables the deformable sealing feature to be achieved while maintaining manufacturability through standard fabrication processes.
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
This configuration enhances the sealing between the thermoplastic liner and metal boss, preventing leakage and ensuring the cylinder can maintain high internal pressures effectively, thereby improving the structural integrity and operational reliability of composite pressure vessels.
Implementation Method 1
a relief space region having a sidewall at a first position that is deformable to a second position which reduces a distance between the sidewall and the metal boss
Implementation Method 2
ensuring the cylinder can maintain high internal pressures effectively
Data Source
AI summary
Provided is a system and method for securing a seal between a thermoplastic liner and a metal boss for a composite cylinder. A metal boss can be integrated with a thermoplastic liner during a molding process. A bushing can be inserted into the metal boss and coupled thereto via threading. The bushing can further include a relief space region having a sidewall that is deformed from a first position to a second position in order to decrease a distance of the metal boss to the sidewall of the bushing, wherein the decrease provides a seal between the metal boss and the thermoplastic liner.