Multilayer Fuel Tube Structure With Low-Extractable Inner Layer
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Solution Overview
Problem
Current multilayer tube structures used for transporting petrol, especially alcoholic fuel, fail to meet the new criteria set by car manufacturers due to high extractable material content, leading to potential blockage of vehicle engine injectors and other performance issues such as permeability and durability challenges.
Innovation Solution
A multilayer tubular structure is designed with a barrier layer and interior layers containing minimal plasticizer, primarily composed of aliphatic polyamides, to reduce extractable material content and enhance barrier properties, specifically using a configuration where interior layers have 0 to 1.5% plasticizer by weight and exterior layers have up to 15% plasticizer, ensuring low permeability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multilayer tube structures are used for transporting alcoholic fuel, then barrier properties and mechanical strength are improved, but extractable material content increases causing injector blockage
Solution Approach 1:
The patent applies local quality by differentiating plasticizer content across different layers of the multilayer tube structure. The inner layer (in contact with fuel) contains 0-1.5% plasticizer to minimize extractables, while outer layers contain up to 15% plasticizer to maintain mechanical properties and flexibility. This spatial differentiation of material composition resolves the contradiction between barrier performance and extractable content.
Solution Approach 2:
The patent uses composite materials by combining multiple polymer layers with different plasticizer contents and compositions. The structure includes an inner layer with low plasticizer content (0-1.5%) and outer layers with higher plasticizer content (up to 15%), creating a composite structure that simultaneously achieves low extractable content and adequate mechanical strength for fuel transport applications.
2Object-generated harmful factors
If plasticizer content in interior layers is reduced to meet extractable criteria, then extractable material content decreases, but mechanical flexibility and ease of assembly may worsen
Solution Approach 1:
The patent segments the tube structure into multiple functional layers with different plasticizer contents. The inner layer (0-1.5% plasticizer) provides low extractable content for fuel contact, while outer layers (up to 15% plasticizer) provide mechanical flexibility and ease of assembly. This segmentation allows each layer to optimize for its specific function without compromising overall performance.
Solution Approach 2:
The patent applies local quality by concentrating plasticizer in outer layers rather than uniformly distributing it throughout all layers. This localized placement of plasticizer maintains flexibility where needed (outer layers) while minimizing extractables where critical (inner layer in contact with fuel).
3Quantity of substance
If multilayer structure with barrier layer is used, then permeability to fuel is reduced, but extractable material blocks injectors
Solution Approach 1:
The patent applies local quality by creating a low-plasticizer zone (0-1.5%) in the inner layer that directly contacts the fuel and is closest to the barrier layer. This localized composition control minimizes extractable material release into the fuel while maintaining the barrier layer's permeability control function.
Solution Approach 2:
The patent uses composite materials with differentiated plasticizer content across layers. The inner layer composite (0-1.5% plasticizer) minimizes extractables, while the barrier layer and outer layers provide fuel permeability control and mechanical properties, respectively. This composite structure resolves the contradiction between permeability control and extractable content.
4Ease of manufacture
If conventional multilayer tubes are used, then manufacturing and assembly are facilitated, but delamination and leakage occur under fuel exposure
Solution Approach 1:
The patent applies parameter changes by modifying the plasticizer content parameter in the inner layer (0-1.5%) compared to conventional tubes. This parameter change improves adhesion between layers under fuel exposure while the outer layers maintain flexibility for assembly. The controlled plasticizer distribution prevents delamination without sacrificing ease of manufacture.
Data Source
AI summary
The present invention relates to a multilayer tubular structure (MLT) for the transport of fluids, in particular gasoline, especially alcoholic gasoline, comprising from the outside in at least one barrier layer (1) and at least one inner layer (2) located below the barrier layer, said inner layer (2) or all of the layers (2) and any other layers located below the barrier layer, containing on average from 0 to 1.5% by weight of plasticizer relative respectively to the total weight of the composition of layer (2) or to the total weight of all the compositions of layers (2) and any other layers located below the barrier layer, said inner layer (2) comprising predominantly at least one aliphatic polyamide or consisting of more than 75% aliphatic motifs,said aliphatic polyamide being selected from: - a polyamide denoted A having an average number of carbon atoms per nitrogen atom denoted CA of 4 to 8.5, advantageously from 4 to 7; - a polyamide denoted B and an average number of carbon atoms per nitrogen atom denoted CB of 7 to 10, advantageously from 7.5 to 9.5; - a polyamide denoted C having an average number of carbon atoms per nitrogen atom denoted Cc of 9 to 18, advantageously from 10 to 18; provided that when said inner layer (2) comprises at least three polyamides, at least one of said polyamides A, B or C is excluded.