Multi-layer Fuel Tube with Nylon 9T Barrier
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Solution Overview
Problem
Conventional multi-layer tubes for fuel conveyance in vehicles face limitations in permeability, especially with alcohol fuels, mechanical properties, and temperature resistance, leading to issues like cracking and reduced flexibility, which are exacerbated by increasing pressure and temperature demands in modern engines.
Innovation Solution
A multi-layer tube structure comprising an innermost layer of nylon 9T, an intermediate layer of polyamide 6, a tie layer of co-polyamide, and an external layer of polyamide 12, which enhances permeation resistance, mechanical properties, and temperature resistance, while maintaining flexibility and reducing weight and production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the layer thickness is increased to reduce permeability, then permeation resistance is improved, but flexibility is reduced and weight increases
Solution Approach 1:
The patent employs a multi-layer composite structure combining nylon 9T, polyamide 6, and polyamide 12. Each layer contributes specific properties: nylon 9T provides barrier performance against alcohol fuels, polyamide 6 offers mechanical strength, and polyamide 12 delivers flexibility and impact resistance. This composite approach achieves superior permeation resistance without requiring excessive thickness, thus avoiding weight penalty and maintaining flexibility.
Solution Approach 2:
Different layers are assigned specific functions based on local requirements: the innermost nylon 9T layer specifically targets permeation resistance against alcohol fuels, while the outer polyamide 12 layer provides flexibility and impact resistance. This localized functional assignment optimizes overall performance without uniformly increasing thickness throughout the tube structure.
2Reliability
If the layer thickness is increased to reduce permeability, then permeation resistance is improved, but the tube flexibility is reduced
Solution Approach 1:
The multi-layer composite structure allows each layer to specialize: nylon 9T for barrier properties, polyamide 6 for mechanical strength, and polyamide 12 for flexibility. This division of labor achieves high permeation resistance while the polyamide 12 layer ensures the tube maintains adequate flexibility for installation and operation.
Solution Approach 2:
The outer polyamide 12 layer is specifically designed to provide flexibility and impact resistance, while the inner nylon 9T layer handles permeation resistance. This local quality assignment ensures the tube remains flexible despite the presence of thick barrier layers.
3Strength
If conventional polyamide resins are used, then mechanical resistance and flexibility are ensured, but permeability requirements are not met
Solution Approach 1:
The patent combines three different polyamide materials, each with distinct properties. Nylon 9T provides excellent barrier performance against alcohol fuels, while polyamide 6 and polyamide 12 maintain mechanical strength and flexibility. This composite approach overcomes the limitation of single-material tubes that cannot simultaneously satisfy both mechanical and permeability requirements.
Solution Approach 2:
The innermost layer uses nylon 9T specifically optimized for permeation resistance against alcohol fuels, while outer layers use polyamide 6 and 12 optimized for mechanical properties. This local quality differentiation allows each layer to excel at its specific function without compromising overall tube performance.
4Temperature
If materials resistant to high temperatures are used, then temperature resistance is improved, but workability during assembly is reduced
Solution Approach 1:
The multi-layer structure allows the polyamide 12 outer layer to provide impact resistance and workability at lower temperatures during assembly, while the nylon 9T and polyamide 6 layers provide high-temperature resistance during operation. This composite approach decouples the conflicting requirements of assembly workability and operating temperature resistance.
Solution Approach 2:
Different layers are optimized for different temperature conditions: the outer polyamide 12 layer provides flexibility and workability during cold assembly operations, while the inner nylon 9T and polyamide 6 layers provide thermal stability during high-temperature engine operation. This local quality assignment resolves the contradiction between assembly ease and temperature resistance.
Data Source
AI summary
A motor vehicle fuel conveying multi-layer co-extruded tube (1) comprising at least an innermost first layer (2) of a polyamide resin (P9T) consisting of a dicarboxylic acid component and a diamine component, wherein 60÷100% of the dicarboxylic acid component is terephthalic acid and 60÷100% of the diamine component is selected from 1,9-nonanediamine and 2-methyl-1,8-octanediamine; an intermediate second layer (3) of polyamide 6 (PA 6); an intermediate co-polyamide (CoPA)-based tie layer (4); and an external fourth layer of polyamide 12 (PA12).