Mechanically Retained Seal Geometry for Controlled Compression
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Solution Overview
Problem
Rubber seal rings used in aircraft fuel tanks are prone to falling out or over-compressing due to dimensional tolerance issues and environmental factors, leading to potential leaks and reduced longevity, with existing adhesive solutions being hazardous and difficult to control.
Innovation Solution
A seal design featuring a pair of side walls, a base, and a rounded peak with concave and convex surfaces that allows for controlled compressibility and mechanical retention within a channel recess, reducing internal stresses and the need for adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive is used to secure the seal ring in the groove, then the seal ring is prevented from falling out or rotating, but the adhesive is hazardous to operators and requires PPE, and requires additional curing time
Solution Approach 1:
The invention removes the adhesive bonding step entirely from the seal installation process. The seal is retained in the groove solely through mechanical means - the interference fit between the seal cross-section and the groove dimensions - eliminating the need for hazardous chemicals and their associated safety requirements and curing times.
Solution Approach 2:
The seal structure itself provides the retention function that previously required adhesive. The seal's cross-sectional dimensions are designed to create sufficient friction and mechanical interference with the groove to prevent falling out or rotating, making the system self-retaining without external bonding agents.
2Reliability
If adhesive is used to secure the seal ring, then the seal ring is prevented from falling out, but the additional thickness of the bonding agent is difficult to control, resulting in poor quality seal ring compression and potential leak paths
Solution Approach 1:
The invention eliminates the adhesive layer from the assembly, removing the source of dimensional control problems. Without adhesive, there is no variable thickness bonding agent to create inconsistent seal compression or potential leak paths.
Solution Approach 2:
The invention changes the retention mechanism from chemical bonding with variable thickness to mechanical interference fit with controlled dimensions. The seal and groove are designed with specific dimensional relationships that provide consistent retention without the need for adhesive thickness control.
3Adaptability or versatility
If the seal is allowed to compress freely, then the seal can accommodate dimensional tolerances and environmental effects, but the seal over-compresses leading to rupture and tearing due to internal stresses and shear forces
Solution Approach 1:
The invention changes the compressibility parameter of the seal by modifying its cross-sectional geometry. The non-circular cross-section with specific width-to-height ratios and rounded features creates controlled stress distribution that allows the seal to accommodate tolerances and environmental effects without over-compression leading to rupture.
Solution Approach 2:
The invention applies curvature to the seal cross-section with rounded peaks and gentle slopes between concave surfaces. This curvature distributes stresses more evenly throughout the seal material, preventing stress concentration that would lead to rupture while maintaining the ability to accommodate dimensional variations.
4Manufacturing precision
If the seal has a narrow cross-section, then the seal fits tightly in the groove, but the seal is prone to over-compression and rupture due to concentrated stresses
Solution Approach 1:
The invention applies curvature to the seal cross-section with rounded peaks and gentle slopes. This distributes the compressive stresses over a larger volume of material and prevents stress concentration at sharp corners, allowing the seal to maintain tight groove fit while resisting rupture from over-compression.
Solution Approach 2:
The invention creates a composite cross-sectional geometry that combines narrow overall dimensions for tight fit with localized rounded features that distribute stress. The cross-section integrates both the space-efficient narrow profile and the stress-distributing curved surfaces into a single optimized structure.
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 seal design enhances durability and prevents rupture by limiting compressibility to 25% or less, ensuring a secure fit and easy installation without adhesives, thus improving the longevity and reliability of the seal.
Implementation Method 1
the first and second concave surfaces extend to the rounded peak with a gentle slope, i.e. relatively large radius. This reduces the internal stresses of the seal, allowing the seal height to be compressed and the seal cross sectional shape (taken in the width-height plane) to deform in the channel recess without excessive shear forces that could otherwise lead to rupture and failure.
Implementation Method 2
the seal is configured such that when the seal is seated on the floor of the channel recess the apex of the rounded peak projects no more than 25% of the seal height from the surface of the first component in which the channel recess is formed so as to define a maximum compressibility of the seal height
Data Source
Figure 1~2
Figure 3~4
Figure 5~6A
AI summary
A seal (200) has a pair of side walls (202, 204), a base extending between the side walls, a first concave surface (220) extending inwardly from one of the side walls, a second concave surface (240) extending inwardly from the other side wall, and a convex surface (230) extending between the first concave and second concave surface to form a rounded peak (250) having an apex (255). The seal has a seal width (Sd) defined between the seal side walls, and a seal height (Sh) defined between the apex of the rounded peak and the base (206). The width is at least twice the height of the seal. The seal is located in a channel recess (150) of a first component (10) opposite a second component (20) to seal between the first component and the second component, the channel recess having a floor (156) and a height (RH) defined between the floor and a surface of the first component in which the channel recess is formed. The seal is configured such that when the seal is seated on the floor of the channel recess the apex of the rounded peak projects no more than 25% of the seal height from the surface of the first component in which the channel recess is formed so as to define the maximum compressibility of the seal height when the second component is brought into contact with the surface of the first component. The channel recess has a seal retainer for mechanically retaining the seal in the channel recess.