Hooked Tube Fitting Crimp for High-Pressure Connection Security

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Solution Overview

Problem

Existing fittings used in air conditioning and refrigeration applications fail to secure a sufficient and stiff connection between the fitting and the tube at high pressures, such as those above 40 bar, leading to loose connections and potential tube dislodgment.

Innovation Solution

A fitting with a hook element that engages a crimp on the tubular element, providing a form-fit and force-fit connection, which is secured by reducing the diameter of the fitting using a pressing tool or external cap, ensuring the connection remains secure even at high pressures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional crimping fittings are used, then the connection is sufficient for low pressures, but the connection becomes loose at high pressures above 40 bar

Engineering Contradiction:
Improveconnection securityVSAvoidpressure resistance
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The connection mechanism is segmented into multiple independent elements: the crimped connection provides initial mechanical bonding, while the hook element provides additional engagement with the tubular element. This segmentation allows each element to contribute to pressure resistance without compromising connection security at low pressures.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The hook element is pre-formed on the fitting before connection, positioned to engage with the tubular element during crimping. This preliminary preparation ensures that when pressure increases, the hook element is already in place to prevent dislodgment, rather than relying solely on the crimped connection.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the fitting diameter is reduced by pressing, then the connection security increases, but the manufacturing complexity increases

Engineering Contradiction:
Improveconnection securityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The hook element is pre-formed on the fitting during manufacturing, before the connection process. This preliminary formation of the engagement feature adds minimal complexity to the fitting manufacturing while ensuring the connection security is achieved through the pre-positioned hook element that engages the tubular element during crimping.

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 proposed fitting securely fastens the tube to the fitting at high pressures, preventing dislodgment even at pressures up to 200 bar, thus addressing the limitations of existing fittings in ACR applications.

Implementation Method 1

the diameter of the first connection element can be reduced in a radial direction by at least partly pressing the first connection element with a pressing tool or with an external cap

Methodology Applied
Scientific EffectMechanical compression: Compression

Implementation Method 2

The proposed fitting securely fastens the tube to the fitting at high pressures, preventing dislodgment

Methodology Applied
Scientific EffectMechanical interlocking: Mechanical Fastener

Data Source

PatentEP3290769B1Fitting for connecting to a tubular element, tubing connection and a method for connecting a fitting to a tubular element
Publication Date: 2025.05.21 CONEX IPR LTD
  • EP3290769B1 patent drawingFigure 1~2
  • EP3290769B1 patent drawingFigure 3~4
  • EP3290769B1 patent drawingFigure 5~7

AI summary

The invention relates to a Fitting (3, 3') for connecting to a tubular element (5, 5') having a first end section (9, 9') comprising at least one first connection element (21, 21'), wherein the diameter of at least a part of the first connection element (21, 21') can be reduced in a radial direction in order to produce a connection, wherein the first connection element comprises at least one first hook element (21, 21') and/or at least one first crimp configured to be connected in force-fit and/or form-fit manner to at least one second crimp (7, 7') and/or at least one second hook element formed on the outer surface of the tubular element (5, 5'), when the diameter of at least a part of the first connection element is reduced, as well as a tubing connection and a method for connecting a fitting to a tubular element.