Crimp Fitting O-Ring Channel Structure for High-Pressure Tube Sealing
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Solution Overview
Problem
Conventional soldering and brazing techniques for joining high-pressure tubes in refrigeration and HVAC systems pose safety risks and are impractical, and existing crimp fittings struggle to achieve leakless connections under significant pressure and axial tension loads.
Innovation Solution
The use of sleeve crimp fittings with internal O-ring channels and central protrusions to form a high-pressure seal, combined with radial crimping that induces plastic deformation and work hardening, creating interlocking geometry to prevent pullout and enhance sealing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If soldering or brazing techniques are used to join tube ends, then strong connections can be achieved, but fire risk increases and the process becomes complex and impractical for high-pressure applications
Solution Approach 1:
The patent replaces thermal joining processes (soldering/brazing) with a mechanical crimping system. A crimp fitting with interlocking geometry mechanically engages with the tube ends, eliminating the need for torches and heat application, thereby removing fire risk while maintaining connection strength through mechanical interlocking and work hardening
Solution Approach 2:
The patent introduces a crimp fitting as an intermediary component between tube ends. This fitting includes O-rings for sealing and crimped regions for mechanical engagement, serving as a mediator that joins tubes without direct thermal contact or complex procedures
2Ease of manufacture
If conventional crimp fittings are used to join tube ends, then the process is simpler, but leakless connections cannot be achieved under high pressure and axial tension loads
Solution Approach 1:
The patent segments the crimp fitting into distinct functional regions: O-ring channels for sealing, crimped regions for mechanical engagement, and interlocking geometry for load resistance. This segmentation allows each region to specialize in its function, achieving both ease of installation and high sealing reliability under pressure
Solution Approach 2:
The patent changes the physical state of the crimp fitting material through work hardening during crimping. The material transitions from annealed (malleable) to work-hardened (less malleable, stronger), enabling the fitting to resist axial tension loads and maintain sealing reliability while remaining easy to install
3Ease of operation
If tube ends are made appreciably malleable for easier joining, then installation is easier, but axial loads cause deformation and separation from the fitting
Solution Approach 1:
The patent applies preliminary work hardening to the tube ends and crimp fitting during the joining process. The crimping operation intentionally deforms and work hardens the materials before service, creating a strong, load-resistant joint. This preliminary action transforms the material properties in advance, preventing future deformation under axial loads
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 effectively forms joints that can withstand pressures over 2,100 pounds per square inch, providing a reliable and safe connection that resists axial tension loads and prevents leakage.
Implementation Method 1
receive an elastic O-ring that deforms against the end margin of respective one of the two tubes to form a high pressure seal
Implementation Method 2
The plastic deformation work hardens the crimped regions of the fitting and thereby makes such regions of the fitting less malleable after crimping
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(d)
Figure 3(a)~3(b)
AI summary
A crimp fitting comprises a metal tube wall that forms both a cylindrical tube portion and an adjacent annular O-ring channel portion. The tube wall has a first wall thickness along the cylindrical tube portion and a second wall thickness along at least part of the O-ring channel portion. The second wall thickness is less than the first wall thickness. The cylindrical tube portion and O-ring channel are configured and adapted to encircle a cylindrical end portion of a tube when such end portion of the tube is inserted into the fitting.