Constant Width Annular Seal for Pipe Joint Stability

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Solution Overview

Problem

Existing pipe sealing technologies, such as those using press fittings with rubber seals, face issues where the seal can turn or become dislodged during pipe insertion, leading to potential leaks and reduced durability due to uneven cross-sectional areas, especially when the seal is not crimped.

Innovation Solution

An annular seal with a section formed by a succession of circle segments connected by vertices, creating a regular polygon shape, which provides a constant cross-sectional width and increased curvature, stabilizing the seal within the groove and allowing for a bead that creates leakage channels before crimping to ensure proper assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a circular section seal is used, then the seal can be easily manufactured and installed, but it may turn or become dislodged during pipe insertion, compromising sealing reliability

Engineering Contradiction:
Improveseal stabilityVSAvoidseal geometry
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The seal employs a non-circular cross-section with an odd number of circular arcs (at least three) that form a constant width profile. This asymmetric geometry prevents the seal from rotating or becoming dislodged during pipe insertion, as the irregular shape cannot align symmetrically with the circular groove, thereby ensuring stable positioning while maintaining manufacturing feasibility through extrusion processes.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If the seal cross-section is made non-circular to prevent turning, then seal stability improves, but manufacturing complexity increases

Engineering Contradiction:
Improveseal positioning stabilityVSAvoidseal fabrication
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The seal utilizes a constant width profile formed by an odd number of circular arcs with specific radius relationships. This geometric parameter configuration allows the seal to be manufactured using standard extrusion processes while achieving the desired non-circular cross-section. The constant width property ensures uniform material distribution and simplifies the extrusion tooling design, making the manufacturing process feasible despite the complex cross-sectional geometry.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If a seal with greater radius of curvature segments is used, then the seal stabilizes at the bottom of the groove, but the cross-sectional area increases making the assembly harder

Engineering Contradiction:
Improveseal groove stabilizationVSAvoidcrimping force
Core Design Contradiction:
Stability of the object's compositionVSForce

Solution Approach 1:

The seal employs circular arcs with different radii of curvature distributed around its perimeter, with at least three arcs forming the constant width profile. The segments with greater radii of curvature are strategically positioned to contact the groove surfaces, providing stabilization points that prevent the seal from moving or rotating. This localized curvature variation achieves stable positioning while the overall constant width profile controls the total cross-sectional area, balancing stabilization needs with crimping force requirements.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3156698B1Joint with constant cross-section
Publication Date: 2018.08.15 LE JOINTS FRANCAIS SA
  • EP3156698B1 patent drawingFigure 1
  • EP3156698B1 patent drawingFigure 2A~2B
  • EP3156698B1 patent drawingFigure 3

AI summary

The invention relates to an annular seal for ensuring a watertight connection between a first and a second pipe after crimping, comprising an axis of revolution (X-X'), a section of which, parallel to said axis, is a curve formed by a succession of an odd number of circular segments Ci connected by vertices Si, forming a regular polygon, i varying from 1 to 2*n+1, n being a positive integer greater than or equal to 1, vertex Si being the center of the circle passing through vertices Si+n and Si+n+1 modulo 2*n+1. Such a curve is said to have a constant width. The vertices Si advantageously form a polygon.