Press-Connect Fitting Membrane Seal for High-Pressure Leak Prevention

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Solution Overview

Problem

Existing crimp connections in HVAC/R conduit systems are prone to leaks and separation, especially at high pressures, due to imperfections and damage on the copper conduit surfaces, which affect the sealing ability of the O-ring and fitting body.

Innovation Solution

A connection joint with a tubular body and membrane seals having primary and secondary seal features, including radially inwardly extending ribs and bulbous portions, that engage the conduit surface for enhanced sealing and are crimped to achieve metal-to-metal contact, reducing friction and improving sealing reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If an inner O-ring seal is used in existing crimp connections, then installation speed is improved, but sealing reliability deteriorates at high pressures due to surface imperfections

Engineering Contradiction:
Improveinstallation speedVSAvoidsealing reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The sealing function is divided into two independent parts: a membrane seal with primary seal feature for initial sealing, and a secondary seal feature for reinforcement. This segmentation allows each seal feature to perform its specific function, with the primary seal providing immediate sealing and the secondary seal providing backup sealing pressure resistance

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The membrane seal acts as an intermediary element between the fitting body and conduit, providing a compliant sealing interface that can accommodate surface imperfections. The membrane seal with its flexible material bridges the gap between the rigid fitting body and the potentially imperfect conduit surface, ensuring reliable sealing

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If the fitting body is crimped directly to the conduit, then connection strength is improved, but sealing ability deteriorates due to surface imperfections on the conduit

Engineering Contradiction:
Improveconnection strengthVSAvoidsealing ability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The membrane seal is pre-installed within the fitting body before the crimping operation. This preliminary sealing action ensures that the sealing interface is established before the crimping force is applied, preventing surface imperfections from compromising the seal during the high-stress crimping process

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The membrane seal provides a cushioning effect by accommodating surface imperfections and irregularities on the conduit before the crimping force is applied. The compliant material of the membrane seal absorbs and distributes the stress, preventing stress concentration at defect locations that would compromise sealing

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 reliable, leak-proof seal at high pressures by engaging the conduit surface effectively, even with imperfections, and ensures robust connection through crimping, suitable for high-pressure applications.

Implementation Method 1

The membrane seal is configured to sealingly engage an exterior surface of the conduit

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

the tubular body is crimped on opposing sides of the membrane seal to fixedly engage the tubular body to the conduit in metal-to-metal contact

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 3

the tubular body is crimped on opposing sides of the membrane seal to fixedly engage the tubular body to the conduit in metal-to-metal contact

Methodology Applied
Scientific EffectPlasticity: Plasticity

Data Source

PatentEP3425249B1Press-connect fitting with membrane seal
Publication Date: 2021.09.01 MUELLER INDUSTRIES INC
  • EP3425249B1 patent drawingFigure 1
  • EP3425249B1 patent drawingFigure 2~4
  • EP3425249B1 patent drawingFigure 5~7

AI summary

A connection joint for coupling a pair of conduits. The connection joint includes a tubular body having an inlet end and an outlet end that are each configured for receipt of a respective conduit therein. A first membrane seal is located within the tubular body and spaced apart from the inlet end, and a second membrane seal is located within the tubular body and spaced apart from the outlet end. The first and second membrane seals each have a bulbous portion located proximate the inlet end and outlet end, respectively, a tubular sleeve unitary with the bulbous portion located away from the inlet end and outlet end, respectively, and a plurality of radially inwardly extending ribs.