Pre-Assembled Pipe Fitting for Stress-Free O-Ring Sealing

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Solution Overview

Problem

Existing pipe connection technologies, particularly for plastic pipes, face issues with stress corrosion, leakage, and the need for complex assembly, as well as incompatibility with plastic materials due to conical seals and require firm tightening to prevent leaks, which can lead to damage and increased maintenance.

Innovation Solution

A plastic fitting with a pre-assembled design featuring a housing with different diameters, a clamping sleeve, and a nut, utilizing O-rings and a support sleeve to create a stress-free, reusable connection that can withstand high pressures and temperatures, allowing for easy assembly and disassembly with standard tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conical seals and nuts are used to connect pipes, then the connection can be secured, but stress corrosion increases and lead content must be reduced from 2% to 0.2%

Engineering Contradiction:
Improveconnection securityVSAvoidstress corrosion
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes the conical seal and nut components from the connection system, replacing them with a press-fit mechanism using a pressing tool. This extraction eliminates the sources of stress corrosion while maintaining connection security through the interference fit between the pipe outer diameter and the fitting inner diameter.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the threaded mechanical connection system (nut and conical seal) with a press-fit mechanical system. The connection is achieved by pressing the pipe into the fitting with a pressing tool, creating a secure interference fit without the need for threads or conical seals, thereby eliminating stress corrosion.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If plastic pipes are used to replace metal pipes, then affordability and service life are improved, but compatibility with traditional fittings decreases

Engineering Contradiction:
Improvematerial compatibilityVSAvoidfitting assembly
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent changes the connection parameters by eliminating threads and conical seals, using instead a press-fit mechanism with specific dimensional tolerances. The pipe outer diameter and fitting inner diameter are designed to create an interference fit when pressed together, making the system compatible with plastic pipes while maintaining secure connections.

Inventive Principle:
Principle #35Parameter changes

3Loss of time

If pre-assembled fittings are used, then assembly time is reduced, but the ability to accommodate pipe insertion is limited

Engineering Contradiction:
Improveassembly timeVSAvoidpipe insertion
Core Design Contradiction:
Loss of timeVSEase of operation

Solution Approach 1:

The patent applies preliminary action by pre-assembling the O-ring and support sleeve into the fitting before delivery. The O-ring is placed in its groove and the support sleeve is positioned in the fitting, so that when the pipe is inserted, the connection is immediately secure without requiring on-site assembly of these components.

Inventive Principle:
Principle #10Preliminary action

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 secure, leak-proof connection that is stress-free and reusable, compatible with various materials, including plastic, and can withstand high pressures and temperatures, reducing maintenance and assembly complexity while maintaining affordability.

Implementation Method 1

A fitting (100) for connecting water pipes, having a housing (110) with a through bore, an O-ring (120) arranged in a groove in the housing, wherein the O-ring (120) forms a seal

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a clamping sleeve (130) for clamping onto the pipe (200), wherein the clamping sleeve (130) clamps the pipe (200) against the housing (110), thereby fixing the pipe (200) in place

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

a clamping sleeve (130) for clamping onto the pipe (200), wherein the clamping sleeve (130) clamps the pipe (200) against the housing (110), thereby fixing the pipe (200) in place

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Implementation Method 4

a support sleeve (140) inserted into the pipe (200), wherein the support sleeve (140) prevents twisting of the pipe (200) during installation

Methodology Applied
Scientific EffectRigidity:

Data Source

PatentEP3334966B1A fitting to connect water pipes
Publication Date: 2021.11.10 BRAATHEN THOR FROELICH
  • EP3334966B1 patent drawingFigure 1~4

AI summary

A fitting to interconnect water pipes or to connect pipes with valves or mountings. The connector housing (1) has an O-ring seat (1c), constituting two walls of a groove for an O-ring (2). The fitting comprises a clamping sleeve (3), having a first end provided with a flange (3a), which forms a third wall of the O-ring seat (1c) groove. The flange (3a) is retained against the coupling housing by a nut (4) screwed by hand onto outer threads on the coupling housing (1). The clamping sleeve (3) is adapted to be clamped against a pipe (6, 7) which is inserted into the clamping sleeve (3), and the O-ring seals against the outer surface of the pipe (6, 7).