Multilayer Polyamide Tube for Refrigerant Transport
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Solution Overview
Problem
Current tubular structures for transporting refrigerant fluids in automotive air conditioning fail to meet the requirements of high water permeability and hot burst strength simultaneously, while also needing to be watertight and chemically resistant to refrigerants like R134, R-1234yf, and R-1234ze, and environmentally durable.
Innovation Solution
A multilayer tubular structure comprising a long-chain polyamide outer layer and a polyamide inner layer with specific carbon atom ratios, devoid of continuous fibers, and optionally a short-chain polyamide layer, ensuring at least 50% of the total thickness is comprised by the inner layer for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If long-chain polyamides are used, then water permeability is improved, but hot burst strength deteriorates
Solution Approach 1:
The tubular structure is divided into multiple layers with different polyamide chain lengths. The inner layer uses long-chain polyamide for water permeability, while the outer layer uses short-chain polyamide for hot burst strength. This segmentation allows each layer to optimize for its specific function without compromise.
Solution Approach 2:
The invention creates a composite multilayer structure combining different polyamide materials (long-chain and short-chain) in specific configurations. This composite approach integrates the advantageous properties of each material type to achieve overall performance that neither material could provide alone.
2Strength
If short-chain polyamides are used, then hot burst strength is improved, but water permeability deteriorates
Solution Approach 1:
The tubular structure is divided into multiple layers with different polyamide chain lengths. The inner layer uses long-chain polyamide for water permeability, while the outer layer uses short-chain polyamide for hot burst strength. This segmentation allows each layer to optimize for its specific function without compromise.
Solution Approach 2:
The invention creates a composite multilayer structure combining different polyamide materials (long-chain and short-chain) in specific configurations. This composite approach integrates the advantageous properties of each material type to achieve overall performance that neither material could provide alone.
3Reliability
If multilayer structure is implemented, then chemical resistance and watertight properties are improved, but device complexity increases
Solution Approach 1:
Each layer of the multilayer structure is designed with specific local properties tailored to its function. The inner layer provides chemical resistance to refrigerants, while outer layers provide mechanical strength and environmental protection. This local quality optimization achieves high reliability without unnecessary complexity throughout the entire structure.
Data Source
AI summary
A multilayer tubular structure intended for transporting a heat-transfer fluid, the multilayer tubular structure including: a first layer including at least one long-chain polyamide having between 10 and 15 carbon atoms per nitrogen atom and including at least 50% aliphatic units relative to the sum of the units present in the long-chain polyamide; a second layer including at least one polyamide having between 4 and 9 carbon atoms per nitrogen atom, the polyamide including at least 50% aliphatic units relative to the sum of the units present in the polyamide; an optional layer, the first layer containing no continuous fibres, the second layer being in contact with the transported fluid when an optional layer is not present, and the layer or layers representing at least 50% of the total thickness of the tube.