Tube Fitting Assembly With Notch Seating Ferrule
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Solution Overview
Problem
Conventional tube fittings with a single ferrule often fail to achieve a reliable seal, especially with high-pressure applications involving metal tubing, due to the ferrule's difficulty in gripping hard and resistant materials like stainless steel, which requires additional elastomeric seals to prevent leakage.
Innovation Solution
A tube fitting assembly featuring a cylindrical tube with a circumferential notch and a single ferrule that can be plastically deformed to fit into the notch, using a threaded nut to pull the ferrule into a sealing position, creating additional annular seals for enhanced grip and leak-proof performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional single ferrule is used to grip metal tubing, then the device complexity is reduced, but the sealing reliability deteriorates because the ferrule cannot adequately grip hard and resistant materials like stainless steel
Solution Approach 1:
The ferrule is divided into two distinct portions: a gripping portion with external threads for engaging the nut and deforming onto the tube, and a sealing portion that remains relatively undeformed to maintain fluid-tight sealing. This segmentation allows each portion to perform its specific function optimally without compromising the other.
Solution Approach 2:
Different portions of the ferrule are designed with different material properties and deformation characteristics. The gripping portion is designed to deform plastically under nut engagement to secure the tube, while the sealing portion is designed to remain elastic and maintain its sealing capability. This local differentiation of properties resolves the contradiction between gripping effectiveness and sealing reliability.
2Strength
If the ferrule is deformed to grip the tube end, then the gripping strength is improved, but the sealing capability deteriorates because deformation creates irregular surfaces that compromise the seal
Solution Approach 1:
The ferrule is segmented into a gripping portion that undergoes deformation for secure tube engagement and a sealing portion that remains undeformed to maintain smooth sealing surfaces. This spatial separation of deformation zones allows strong gripping without compromising seal integrity.
Solution Approach 2:
The gripping portion is designed to deform first during nut engagement, creating the gripping action before the sealing portion is compressed. This preliminary deformation of the gripping portion ensures that the sealing surfaces remain smooth and intact for effective sealing.
3Reliability
If additional elastomeric seals are added to prevent leakage, then the sealing reliability is improved, but the device complexity increases
Solution Approach 1:
The invention extracts and eliminates the need for additional elastomeric seals by designing a ferrule that achieves sealing through its own structural design. The sealing portion of the ferrule is engineered to create fluid-tight sealing through controlled deformation and geometric configuration, removing the requirement for separate elastomeric sealing components.
Solution Approach 2:
The ferrule serves its own sealing function through its integrated sealing portion, eliminating the need for separate elastomeric seals. The sealing portion deforms in a controlled manner to create sealing surfaces that prevent leakage without requiring additional sealing materials or components.
4Ease of operation
If a threaded nut and body component are used for the pull-up mechanism, then the ease of operation is improved, but the manufacturing precision requirements increase to ensure adequate sealing
Solution Approach 1:
The ferrule is designed with dynamic deformation characteristics that adapt during the tightening process. As the nut is engaged and tightened, the ferrule progressively deforms onto the tube, with the deformation increasing as the nut is tightened. This dynamic response ensures adequate sealing is achieved through the operational process rather than requiring pre-set precision.
Solution Approach 2:
The ferrule's physical parameters (shape, volume, density) change during the tightening process as it deforms onto the tube. This parameter change allows the ferrule to adapt to the tube surface and create sealing contact through the operational process, reducing the need for high manufacturing precision in the initial state.
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 high-performance, leak-proof seal in high-pressure and vibration applications by allowing the ferrule to deform and form additional sealing areas, effectively gripping and sealing the tube end without the need for additional seals.
Implementation Method 1
The tube gripping member has a tapered front end configured to fit into the notch, when the second tube fitting member is pulled up, and seal the tube end
Data Source
AI summary
A tube fitting for sealing an end of a tube uses a notch formed in the exterior surface of the tube as a sealing seat. An internally threaded body is configured to receive an externally threaded end of a nut, while the body and the nut are mounted in a surrounding relationship to the tube end. A ferrule mounted between the nut and the tube is forced to plastically deform and move into the notch to thereby seal the tube end.