Corrugated Tubing Fitting Seal Using a Rounded Annular Edge
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Solution Overview
Problem
Existing methods for connecting corrugated tubing to fittings require significant force to achieve a tight seal, risking damage to the tubing and increased installation time due to the need for metal-to-metal flange seals.
Innovation Solution
A fitting design featuring a nut with a retainer and a body, where the retainer's sealing surface and a pointy annular body sealing edge compress the corrugated tubing, forming a narrow annular seal that requires less compression force, with optimized angles and a rounded apex to prevent damage, allowing for efficient and secure connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal to metal flange seal is formed by compressing the corrugated tube between flat radial extending sealing surfaces, then a tight seal is achieved, but much force is required which increases the risk of tubing damage and installation difficulty
Solution Approach 1:
The sealing mechanism transitions from a distributed flat surface contact to a localized line contact at the apex of the body sealing edge. This concentration of sealing action at a specific point (the apex) allows the seal to form in a narrow annular line, reducing the total compression force needed while maintaining seal integrity. The retainer sealing surface in the valley provides a counterpoint for this localized compression.
Solution Approach 2:
The body sealing edge is designed with a curved apex rather than a flat surface. This spherical/curved geometry concentrates the sealing force at a point, enabling the formation of a tight seal in a narrow annular line. The curvature allows the sealing edge to penetrate and deform the corrugated tubing material more efficiently, reducing the overall force required compared to flat surface compression.
2Reliability
If a flat radial extending sealing surface is used perpendicular to the center axis, then a seal can be formed, but the installation time increases and labor cost increases due to the force required
Solution Approach 1:
The sealing action is localized to a narrow annular line at the apex of the body sealing edge, rather than requiring compression across a wide flat surface. This localized sealing mechanism reduces the time and effort needed for installation, as the seal forms more quickly and with less manual force application.
Solution Approach 2:
The sealing mechanism changes from a two-dimensional flat surface contact to a one-dimensional line contact at the apex. This parameter change in the sealing geometry allows the seal to form more rapidly during installation, reducing labor time while maintaining seal reliability.
3Force
If the mutual angle between body surfaces is made acute to reduce force, then the apex may cut into the tubing compromising the seal, but if made obtuse then too much force is required
Solution Approach 1:
The mutual angle between the body surfaces is optimized to a specific range (30°-60°) that balances two competing requirements: it is acute enough to reduce the compression force needed, but not so acute that the apex cuts into the tubing and compromises the seal. This parameter optimization resolves the contradiction between force reduction and seal integrity.
Solution Approach 2:
The apex angle is designed to be partially acute (within the 30°-60° range) to achieve sufficient force reduction, while the rounded apex geometry prevents excessive cutting action. This partial application of acuteness allows force reduction without compromising seal integrity.
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 enables a tight seal with reduced force requirements, minimizing the risk of tubing damage and simplifying the installation process while allowing for easy disassembly and prolonged fitting life.
Implementation Method 1
compressing a part of the end of the corrugated tube between a retainer sealing surface and the apex of a pointy annular body sealing edge
Data Source
Figure 1
Figure 2~7
Figure 8~9
AI summary
Disclosed is a fitting (1) for use with corrugated tubing (2) having a series of peaks (3) and valleys (4). The fitting (1) comprises a nut (5) having a passage (6) therethrough for receiving the tubing (2) and at least one retainer (7) arranged in the nut (5), wherein the retainer (7) has a retainer sealing surface (8) for placement in a valley (4) of the corrugated tubing (2). The fitting (1) further comprises a body (9) having a pointy annular body sealing edge (10) arranged so that the apex (11) of the body sealing edge (10) is pressed against the retainer sealing surface (8) when the nut (5) and the body (9) are forced toward each other. A method for connecting corrugated tubing (2) to a fitting (1) comprising a nut (5), a retainer (7) and a body (9) and use of a fitting (1) is also disclosed.