Captive Union Nut Plug Connection Eliminates Axial Play
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Solution Overview
Problem
The existing plug-in connections for pipe or hose lines experience axial play and wear due to relative movement of components under dynamic pressure or vibrations, leading to a shorter service life when not under pressure.
Innovation Solution
A plug-in connection design where the union nut is held captive by a resilient snap ring, allowing rotation from an insertion position to a locking position, eliminating axial play by direct contact with the locking ring and providing defined axial movement limits through grooves and a stop on the screw connection body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the locking ring rests against the transition corner between the first recess stage and the second recess stage in the unloaded insertion position, then the pipe section can be inserted, but axial play occurs and components move relative to each other under dynamic pressure or vibrations, leading to wear and shorter service life
Solution Approach 1:
The union nut is designed to rotate from an insertion position to a locking position, transforming the static connection into a dynamic locking mechanism. This rotation activates the second recess stage to engage the locking ring, eliminating axial play and preventing component movement under dynamic conditions, thereby resolving the contradiction between easy insertion and long service life
Solution Approach 2:
The snap ring is pre-installed on the screw connection body in a groove, creating a captive mechanism that guides the union nut's rotation. This preliminary arrangement ensures that when the union nut rotates into the locking position, the snap ring automatically engages with the groove to maintain the locked state, preventing accidental loosening and enhancing reliability without complicating the insertion process
2Ease of operation
If the union nut is allowed to rotate freely during insertion, then the pipe section can be easily inserted, but the union nut may rotate too far or loose completely, causing misalignment or disconnection
Solution Approach 1:
The connection transitions from a static, freely rotatable state during insertion to a dynamically locked state at the final position. The rotation mechanism allows flexibility during insertion but automatically stabilizes the connection when the union nut reaches the locking position, where the second recess stage engages the locking ring and the snap ring secures the union nut to the screw connection body
Solution Approach 2:
The mechanical engagement between the snap ring and the groove in the screw connection body provides immediate feedback when the union nut reaches the correct locked position. This feedback mechanism ensures proper alignment and prevents over-rotation or complete loosening, maintaining connection stability while preserving insertion flexibility
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 prevents axial movement and wear by ensuring the union nut is securely locked in place, enhancing the service life and allowing for easy assembly and detachment of the pipe section.
Implementation Method 1
a resilient snap ring (25) arranged between the screw connection body (10) and the union nut (12)
Implementation Method 2
a resilient expandable locking ring (20) which, when the piece of pipe (13) is inserted, lies in the first step (21) of the recess formed in the union nut (12)
Data Source
Figure 1~3
Figure 4~5a
AI summary
The invention relates to a plug connection for pipe or tube lines, comprising a threaded body and comprising a union nut (12) which is screwed onto the threaded body (10) and which is designed to receive an inserted pipe section in a locking manner. A two-stage recess for receiving a securing ring is arranged in a union nut chamber that receives the securing ring (20) in order to fix the pipe section. The invention is characterized in that the union nut (12) that is screwed on the threaded body (10) is captively secured on the threaded body (10) by means of a resiliently expandable circlip (25) that is arranged between the threaded body (10) and the union nut (12), and the union nut (12) is rotatably arranged between an inserting position and a locking position for the securing ring (20) on the basis of the circlip (25) that engages into grooves (26, 27, 28) formed on the threaded body (10) and the union nut (12).