Multi-Layer Polyamide Fluid Line for Fuel Permeation
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Solution Overview
Problem
Fluid lines for transporting chemically active fuels in vehicles face challenges such as material dissolution, permeability to volatile substances, and mechanical instability, particularly at higher temperatures, which can lead to leaching and quality degradation of the transported fluid.
Innovation Solution
A multi-layer plastic fluid line with an inner layer of polyamide 9T, a second layer of polyamide 12, a third layer of polyamide 612, a fourth layer of polyamide 6, and an outer layer of polyamide 612, providing a barrier against volatile substances and maintaining mechanical stability, even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer polyamide pipe is used, then the manufacturing is simple and cost-effective, but the pipe exhibits high permeability to volatile substances and chemical dissolution
Solution Approach 1:
The patent applies composite materials by creating a multi-layer pipe structure where each layer is made of different polyamide materials (PA6, PA12, PA612) with specific properties. The inner layer uses PA6 for chemical resistance, the middle layer uses PA12 for low water absorption and mechanical stability, and the outer layer uses PA612 for grease and fuel resistance. This composite structure resolves the contradiction by combining materials with complementary properties to achieve high permeability resistance while maintaining structural integrity.
Solution Approach 2:
The patent segments the pipe wall into multiple functional layers, each with a specific thickness and material composition. The inner layer (PA6) has thickness t1, the middle layer (PA12) has thickness t2, and the outer layer (PA612) has thickness t3. This segmentation allows each layer to perform its specific function: the inner layer resists chemical dissolution, the middle layer provides mechanical stability and blocks water, and the outer layer resists external chemical attacks. This resolves the contradiction by distributing functions across segments rather than requiring a single complex material.
2Reliability
If a multi-layer pipe structure is used, then the resistance to chemical dissolution and permeability is improved, but the mechanical stability for connection is reduced
Solution Approach 1:
The patent applies local quality by assigning different material properties to different regions (layers) of the pipe wall. The inner layer (PA6) is optimized for chemical resistance with thickness t1, the middle layer (PA12) is optimized for mechanical stability and low water absorption with thickness t2, and the outer layer (PA612) is optimized for resistance to greases and fuels with thickness t3. This local optimization ensures that each region contributes its strength to the overall pipe performance, resolving the contradiction between chemical resistance and mechanical stability.
Solution Approach 2:
The patent uses composite materials with complementary properties: PA6 provides excellent chemical resistance and low permeability to volatile substances, PA12 provides low water absorption and high mechanical stability, and PA612 provides resistance to greases and fuels. By combining these materials in a multi-layer structure, the pipe achieves both high chemical resistance and adequate mechanical stability for connections, resolving the contradiction between these two requirements.
3Ease of manufacture
If polyamide 6 is used in the fourth layer, then the basic structure is cost-effective and readily available, but the resistance to greases and fuels is insufficient
Solution Approach 1:
The patent segments the protective function against external chemicals into a dedicated outer layer (PA612) with thickness t3, while the basic structural layer (PA6) with thickness t4 provides cost-effective support. This segmentation allows the PA612 layer to specifically address fuel and grease resistance without requiring the entire pipe structure to be made of expensive material, thus maintaining ease of manufacture while improving chemical resistance.
Solution Approach 2:
The outer PA612 layer acts as an intermediary barrier between the internal pipe structure and external harmful substances like greases and fuels. This layer protects the inner PA6 and PA12 layers from direct contact with these chemicals, preventing degradation while maintaining the cost-effective PA6 basic structure. The intermediary layer resolves the contradiction by providing specialized protection without compromising manufacturing ease.
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 multi-layer design significantly reduces leaching and permeability while ensuring adequate mechanical properties for secure connection to other components, maintaining fluid quality and preventing environmental contamination.
Implementation Method 1
the inner, first layer provides a layer with low permeability. In particular, it forms a barrier against volatile substances in the fluid
Implementation Method 2
the inner, first layer is resistant to chemicals and hydrolysis
Implementation Method 3
absorbs only small amounts of water
Data Source
Figure 1~2
AI summary
In the case of a fluid line (10) comprising a pipe (12) of a multilayered plastics material, wherein the pipe (12) surrounds an interior space (14), it is provided that the pipe (12) has an inner, first layer (16) of polyamide 9T (PA9T), a second layer (18) of polyamide 12 (PA12), a third layer (20) of polyamide 612 (PA612), a fourth layer (22) of polyamide 6 (PA6) and an outer, fifth layer (24) of polyamide 612 (PA612), wherein the inner, first layer (16) bounds the interior space (14). Consequently, the invention provides a fluid line (10) that has a reduced dissolution of material, a reduced permeability to volatile substances and nevertheless sufficient mechanical properties for a connection to other components of a line.