Coupling Nut Structure for Secure Thread Engagement Under Pressure
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Solution Overview
Problem
Existing coupling nuts for pressurized fluid systems often result in one conduit separating from the nut under pressure due to insufficient thread engagement, as they can be threaded too shallow, leading to loose connections.
Innovation Solution
A coupling nut design featuring a non-threaded central portion with specific lengths of threaded ends that prevent over-insertion, ensuring both conduits are securely engaged by allowing free rotation if inserted too far, thereby maintaining a face seal and preventing disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coupling nut is designed with threaded ends only, then the conduits can be inserted deeply, but the conduits can be threaded too shallow resulting in insufficient thread engagement and separation under pressure
Solution Approach 1:
The coupling nut is segmented into three distinct zones: a first threaded portion for receiving the first conduit, a non-threaded central portion, and a second threaded portion for receiving the second conduit. This segmentation ensures that each conduit engages with its designated threaded portion, preventing insufficient thread engagement while maintaining ease of insertion.
Solution Approach 2:
The non-threaded central portion acts as an intermediary element between the two threaded portions. It provides a transition zone that prevents either conduit from being inserted too deeply into the opposing threaded portion, thereby ensuring adequate thread engagement for both conduits without requiring complex insertion control mechanisms.
2Reliability
If the non-threaded central portion is made longer, then over-insertion is prevented, but the overall length of the coupling nut increases
Solution Approach 1:
The length of the non-threaded central portion is optimized as a critical parameter. It is designed to be sufficient to prevent over-insertion of either conduit (ensuring the conduit threaded ends remain within the threaded portions), yet minimized to keep the overall coupling nut length compact. This parameter optimization balances reliability with space efficiency.
3Length of stationary object
If the threaded portions are made shorter, then the coupling nut is more compact, but insufficient thread engagement occurs allowing separation under pressure
Solution Approach 1:
By segmenting the coupling nut into distinct threaded and non-threaded portions, the design allows each threaded portion to be optimized for adequate engagement length without requiring the entire coupling nut to be excessively long. The non-threaded central portion absorbs the length necessary to prevent over-insertion, enabling compact threaded sections that maintain sufficient engagement for reliable pressure containment.
Data Source
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AI summary
A coupling nut (108) for joining a pair of conduits (104, 106) is provided. The coupling nut includes a first end (124) and a second end (126). An opening extends between the first end and the second end. The opening has an interior surface. A first coupling nut thread (114) extends along the interior surface at the first end and is constructed and arranged to receive a first conduit thread (110) having a first length (L1). A second coupling nut thread (116) extends along the interior surface at the second end and is constructed and arranged to receive a second conduit thread (112) having a second length (L2). A non-threaded central portion (118) extends between the first coupling nut thread and the second coupling nut thread. The non-threaded central portion (118) has a third length (L5). The third length (L5) of the non-threaded central portion is less than the sum of the first length (L1) of the first conduit thread and the second length (L2) of the second conduit thread.