Pipe Connecting Device Sealing via Inner Ring Geometry

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Solution Overview

Problem

Conventional pipe-connecting devices using an inner ring often experience unstable seal performance due to weak contact pressure at the b seal portion and excessive deformation of the inner ring, leading to fluid flow issues and potential leaks.

Innovation Solution

The pipe-connecting device features a modified inner ring with a tip-contracted outer-circumferential flared surface and a base-contracted diameter-contracted outer circumferential surface, combined with a tubular screwing portion and union nut design that ensures a lower contact pressure between the diameter-contracted tube portion and the tubular screwing portion, allowing for a uniform gap and stable sealing by ensuring the seal element and seal forming portions are effectively pressed against each other.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the union nut is strongly fastened to press the flared portion of the tube, then the seal performance at the a seal portion and c seal portion is improved, but the contact pressure at the b seal portion becomes weak or substantially zero

Engineering Contradiction:
Improveseal performanceVSAvoidcontact pressure at b seal portion
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The invention divides the sealing function into multiple independent seal portions (a seal, b seal, and c seal) that are distributed at different locations along the inner ring and tube interface. Each seal portion contributes to the overall sealing performance, so that even if one seal portion has reduced contact pressure, the other seal portions maintain effective sealing. This segmentation allows the system to achieve reliable sealing without requiring excessively high contact pressure at any single location.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the total press contact forces of the a seal portion and c seal portion are strong, then the seal performance is improved, but the tip end portion of the inner ring body is diameter-reduced and deformed excessively affecting fluid flow

Engineering Contradiction:
Improveseal performanceVSAvoiddiameter of tip end portion of inner ring
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The invention applies different geometric characteristics to different portions of the inner ring. The tip-contracted outer-circumferential flared surface at the tip end has a specific contraction ratio optimized for sealing, while the base-contracted diameter-contracted outer circumferential surface at the base end has a different contraction ratio optimized for maintaining fluid flow. This local differentiation allows each portion to perform its specific function effectively without the adverse effects experienced in conventional uniform designs.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If the conventional inner ring geometry is used, then the manufacturing is simple, but the contact pressure distribution is unstable leading to leak risks

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidseal stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention modifies the geometric parameters of the inner ring, specifically the contraction ratios of the outer circumferential surfaces. The tip-contracted outer-circumferential flared surface and base-contracted diameter-contracted outer circumferential surface have optimized contraction ratios that differ from conventional designs. These parameter changes create a more stable contact pressure distribution across the seal portions, improving sealing reliability while maintaining manufacturing feasibility through standard forming processes.

Inventive Principle:
Principle #35Parameter changes

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

This configuration enhances the sealing performance by maintaining a uniform gap between the tubular screwing portion and the diameter-contracted tube portion, ensuring the seal element and seal forming portions are strongly pressed together, thus preventing leaks and maintaining fluid flow integrity.

Implementation Method 1

the end portion of the tube is flared and deformed by the annular large-diameter portion

Methodology Applied
Scientific EffectFlaring deformation: Deformation

Implementation Method 2

the union nut is fastened and crew-advanced, and this screw advancement causes the union nut to press the tube having the inner ring in the axial direction

Methodology Applied
Scientific EffectMechanical compression: Compression

Implementation Method 3

the seal element portion (y) and the seal forming portion (k) are pressed against each other to achieve sealing

Methodology Applied
Scientific EffectSealing through contact pressure: Pressure Increase

Data Source

PatentEP3001086B1Pipe connecting device
Publication Date: 2018.08.08 NIPPON PILLAR PACKING CO LTD
  • EP3001086B1 patent drawingFigure 1
  • EP3001086B1 patent drawingFigure 2
  • EP3001086B1 patent drawingFigure 3

AI summary

A more improved pipe-connecting device is provided in which a seal portion formed by a basal end portion of an inner ring and a pipe joint body satisfactorily functions, and a tip-end portion of the inner ring is not excessively diameter-contracted and deformed. In a pipe-connecting device having a pipe joint body 1, a union nut 2, and an inner ring 3 which is to be press-inserted into an end of a tube, a seal element portion y is formed in a basal end portion of the inner ring 3, and a seal forming portion k of the pipe joint body 1 is formed. The pipe-connecting device has a configuration where, in an assembled state, the seal element portion y and the seal forming portion k are pressed against each other, and a diameter-contracted tube portion 4c which is in a tube end portion 4C, and which is fitted onto a base-contracted diameter-contracted outer circumferential surface 3c, and a tubular screwing portion 1A are pressed against each other by a contact pressure which is lower than a contact pressure between the seal element portion y and the seal forming portion k, or separated from each other.