Push-fit Pipe Fitting Support Sleeve Retention Design
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Solution Overview
Problem
Existing push-fit pipe fitting systems face issues with support sleeves being stripped out during pipe withdrawal, leading to inconvenience and potential damage to sealing rings or gripping means, and previous solutions like rigid annular bars cause pipe diameter increase and insertion difficulties.
Innovation Solution
A support sleeve with radially outward and axially extending tongues having an arcuate profile, which provides retention without deforming the pipe diameter and allows easy insertion, made from stainless steel with specific dimensions and projections to prevent withdrawal without affecting existing jointing practices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid annular barb is provided on the support sleeve to prevent stripping, then the support sleeve can be retained in the pipe, but the outside diameter of the pipe increases locally and insertion becomes difficult
Solution Approach 1:
The patent replaces rigid annular barbs with a flexible circumferential groove that forms a retaining ring. This flexible structure can deform during insertion to accommodate the pipe without increasing its outside diameter, yet provides sufficient retention force to prevent stripping during withdrawal. The flexibility allows the groove to conform to the pipe surface while maintaining its retaining function.
Solution Approach 2:
The patent changes the physical state of the retaining structure from rigid to flexible. By using a circumferential groove instead of rigid barbs, the structure can dynamically adjust its parameters (shape, position) during insertion and service, allowing it to provide retention without permanently deforming the pipe diameter.
2Ease of manufacture
If the support sleeve is made with a simple cylindrical shape, then manufacture is easy, but the sleeve can be stripped out during pipe withdrawal
Solution Approach 1:
The patent divides the support sleeve into functional segments: a body portion and a circumferential groove. This segmentation allows the simple cylindrical body to be easily manufactured while the added groove feature provides the necessary retention function without complicating the overall manufacturing process significantly.
Solution Approach 2:
The circumferential groove acts as a flexible retaining feature that can deform during installation and service. This flexible structure provides reliable retention against stripping forces while maintaining compatibility with standard manufacturing processes for cylindrical components.
3Reliability
If the support sleeve uses a rigid retaining structure, then retention during withdrawal is improved, but the structure causes local deformation of the pipe and is difficult to insert
Solution Approach 1:
The circumferential groove provides a flexible retaining structure that resists withdrawal forces without causing permanent deformation to the pipe's outside diameter. The groove can elastically deform during insertion and service, maintaining the pipe's original shape while providing sufficient retention.
Solution Approach 2:
The retaining structure transitions from a static rigid form to a dynamic flexible form. The circumferential groove can change its shape and position in response to insertion and withdrawal forces, allowing it to provide retention without permanently altering the pipe's geometry.
Data Source
Figure 1~4
AI summary
A push-fit pipe fitting system comprises a fitting having a body portion defining a bore for receiving a pipe, the said bore being provided with gripping means for retaining the pipe within the bore, a seal for effecting a seal between the pipe and the fitting, and a support sleeve. The support sleeve has a nose portion for capping an end portion of the pipe and a spigot portion for location within the pipe. The spigot portion is provided with at least one tongue extending both radially outwardly and axially towards the nose portion. The tongue has a distal end portion with an arcuate profile.