Multilobed Elastomer Seal for Fuel Tank Closure
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Solution Overview
Problem
Current closure systems for fuel tanks face challenges in achieving impermeability to both hydrocarbons and alcohol-containing additives, with existing elastomer seals compromising on durability and sealing capability due to differing material moduli and chemical properties.
Innovation Solution
A multilobed elastomer seal with distinct sealing lips made of different materials, one impermeable to hydrocarbons and the other to alcohol-containing media, integrated with a thermoplastic supporting body to ensure stability and prevent distortion, forming a diffusion barrier with an air gap or concentric sealing rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluoroelastomers with greater fluorine component are used to ensure alcohol resistance, then alcohol resistance is improved, but material hardness increases and glass transition temperature increases, leading to reduced durability and sealing capability
Solution Approach 1:
The sealing ring is divided into multiple sealing lips made of different elastomer materials. Specifically, at least one sealing lip is made of fluoroelastomer for alcohol resistance, while at least one other sealing lip is made of different elastomer material for hydrocarbon resistance. This segmentation allows each lip to specialize in resisting specific chemicals without compromising overall seal performance.
Solution Approach 2:
Different regions of the sealing ring have different material properties tailored to local requirements. The sealing lips exposed to alcohol-containing fuels are made of fluoroelastomer, while other lips are made of elastomers optimized for hydrocarbon resistance. This local quality approach ensures optimal chemical resistance at each interface without uniformly increasing hardness throughout the entire seal.
2Reliability
If elastomer seals are molded together from different materials in one piece, then both hydrocarbon and alcohol resistance are achieved, but differing moduli of elasticity cause insufficient stability and shearing forces that reduce seal lifetime
Solution Approach 1:
The sealing ring is segmented into multiple distinct sealing lips that are molded together, with each lip made of different elastomer material. This segmentation allows each material to perform its specialized function while maintaining structural integrity through the molded integration.
Solution Approach 2:
The sealing ring is formed as a composite structure combining multiple elastomer materials with different properties. The composite design integrates fluoroelastomer for alcohol resistance with other elastomers for hydrocarbon resistance, creating a unified seal that leverages the strengths of each material while distributing mechanical stresses.
3Ease of manufacture
If a single elastomer material is used for the sealing ring, then manufacturing is simple, but the seal cannot simultaneously resist both hydrocarbons and alcohol-containing additives
Solution Approach 1:
The sealing ring is segmented into multiple sealing lips made of different elastomer materials, each optimized for specific chemical resistance. This segmentation enables the seal to handle multiple fuel types while maintaining manufacturability through integrated molding processes.
Solution Approach 2:
The sealing ring uses composite elastomer materials with different chemical resistance properties in different regions. This composite approach allows the seal to adapt to various fuel compositions containing hydrocarbons, alcohols, or their mixtures, while still being manufacturable as a single integrated component.
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 a stable and durable seal that meets regulatory impermeability standards, effectively resisting mechanical loading and maintaining sealing integrity under varying fuel conditions.
Implementation Method 1
The property of low permeability of elastomer seals is in inverse proportion to the sealing capability of the material
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a closure system on a fuel tank (1) comprising an opening (2) in the wall of the fuel tank (1) and a closure cover (6) which covers the opening (2) and clamps at least one elastomer seal (5) between itself and a border of the tank wall enclosing the opening (2), the elastomer seal (5) being formed as a multilobed sealing cord or multilobed sealing ring surrounding the opening (2), in such a way that it forms a number of sealing lips (11) that are spaced apart from one another, at least two spaced-apart sealing lips (11) of the elastomer seal (5) consisting of different materials, one of which is impermeable to hydrocarbons and a second is impermeable to alcohol-containing media or alcohol-containing additives.