Resin Fuel Tank Joint Part with Multi-Layer Barrier and Welding Structure
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Solution Overview
Problem
Resin-made joint parts for automotive fuel tanks, particularly connecting pipes and valves, face issues with adhesion to the tank's outermost layer and permeation barriers, leading to fuel leakage due to insufficient weldability and barrier properties.
Innovation Solution
A joint part with a two-layer structure comprising a cylindrical barrier layer made by blending polyethylene into ethylene vinyl alcohol copolymer, polyamide, or polyester, and a cylindrical welding layer of high-density polyethylene, enhancing both weldability and barrier properties against fuel permeation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a welding member made of polyethylene resin is used to improve weldability between the joint part and the resin fuel tank, then the weldability is improved, but the barrier effect against fuel permeation becomes insufficient
Solution Approach 1:
The welding member is divided into multiple functional layers: an outer layer made of polyethylene resin for weldability, and an inner layer made of high barrier material (such as EVOH or polyamide) for preventing fuel permeation. This segmentation allows each layer to perform its specific function optimally without compromising the other.
Solution Approach 2:
The welding member uses a composite structure combining polyethylene resin with high barrier materials like ethylene vinyl alcohol copolymer (EVOH) or polyamide. This composite material approach integrates the advantages of both materials: the excellent weldability of polyethylene and the superior barrier properties of the high barrier material, resolving the contradiction between weldability and permeation prevention.
2Manufacturing precision
If the thickness of the welding member is increased to maintain welding accuracy, then welding precision is improved, but the barrier effect against fuel permeation remains insufficient
Solution Approach 1:
Instead of increasing the overall thickness uniformly, the welding member is segmented into functional layers with the barrier material positioned at the fuel-contact interface. This allows thin-walled designs to maintain both welding accuracy and effective barrier protection, as the barrier function is concentrated in the inner layer rather than requiring uniform thickness throughout.
Solution Approach 2:
The composite structure with high barrier material layers provides enhanced permeation resistance without requiring increased overall thickness. The barrier materials (EVOH, polyamide) have superior fuel permeation resistance properties, allowing the welding member to maintain effective barrier function even with reduced thickness compared to conventional single-layer designs.
3Device complexity
If a single-layer welding member is used to simplify the structure, then device complexity is reduced, but both weldability and barrier property cannot be simultaneously achieved
Solution Approach 1:
The welding member is segmented into distinct functional layers: an outer polyethylene layer for weldability and an inner barrier layer for permeation prevention. This segmentation allows each layer to be optimized for its specific function while maintaining a relatively simple overall structure that can be manufactured using conventional multi-layer extrusion or co-molding techniques.
Solution Approach 2:
The use of composite materials with compatible thermal and mechanical properties allows the multi-layer structure to be manufactured as an integrated component. The polyethylene and barrier material layers are bonded together to form a unified welding member that provides both weldability and barrier properties simultaneously, achieving functional integration without excessive structural complexity.
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 solution provides excellent weldability and a high barrier property, preventing fuel leakage and maintaining integrity under severe conditions, including low temperatures and impacts.
Implementation Method 1
a welding layer formed by the following (B) on at least one surface of an inner periphery and an outer periphery of the barrier layer; (B) a high density polyethylene or a modified high density polyethylene
Implementation Method 2
at least the welding portion comprises an approximate cylindrical barrier layer formed by the following (A); (A) a compound material obtained by blending polyethylene into at least one selected from the group consisting of an ethylene vinyl alcohol copolymer, polyamide, polyester and liquid crystal polymer
Data Source
AI summary
A joint part including a welding portion with a rim of an opening of a fuel resin tank as well as a high barrier property on its interface. The joint part has a multi-layer structure including a barrier layer and at least one of an inner layer and an outer layer coaxially laminated on an inner periphery and/or an outer periphery of the barrier layer, respectively, wherein the barrier layer is formed by a compound material composed of one or more of fuel permeation-resistant resin, such as ethylene vinyl alcohol copolymer, polyamide polyester or liquid crystal polymer, and polyethylene, while the inner layer and the outer layer are composed of high-density polyethylene or modified high-density polyethylene.