Nested Sleeve Flexible Expansion Joint for Axial Movement
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Solution Overview
Problem
Conventional flexible expansion joints fail to maintain a liquid-tight sealed state when the distance between pipes increases beyond the allowable axial length, especially during unexpected events like earthquakes or ground liquefaction, due to limitations in their length and coaxiality deviation, leading to potential disconnection and leakage.
Innovation Solution
A flexible expansion joint design featuring nested sleeves with sealing members and length limiters that allow axial movement and bending, including a brake mechanism to maintain sealing until external forces exceed a threshold, enabling the joint to lengthen by the overlap length plus predetermined limits, ensuring continuous liquid-tight connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the length of the flexible expansion joint is increased to increase the allowable axial length, then the ability to cope with distance changes between pipes is improved, but the allowable coaxiality deviation is reduced and the device becomes more complex
Solution Approach 1:
The patent employs nested sleeves where an inner sleeve is placed inside an outer sleeve, both capable of axial movement. This nested configuration allows the expansion joint to achieve greater allowable axial length through the combined movement ranges of multiple sleeves, rather than requiring a single excessively long component. The nesting approach maintains compact construction while extending the functional length capability.
Solution Approach 2:
The flexible expansion joint is divided into multiple functional segments including the inner sleeve, outer sleeve, sealing members, and length limiters. Each segment performs a specific function: the inner and outer sleeves provide axial movement capability, sealing members maintain liquid-tight seals, and length limiters prevent excessive extension. This segmentation allows the system to achieve extended allowable axial length through coordinated movement of multiple components rather than requiring a single complex component.
2Length of moving object
If the length of the flexible expansion joint is increased to increase the allowable axial length, then the ability to cope with distance changes between pipes is improved, but the coaxiality deviation tolerance is reduced
Solution Approach 1:
The nested sleeve configuration allows each sleeve to independently accommodate some degree of misalignment while providing axial movement. The inner sleeve can move axially relative to the outer sleeve, and both can tolerate certain coaxiality deviations, effectively distributing the alignment tolerance across multiple components rather than requiring high precision across a single long component.
Solution Approach 2:
The patent employs dynamic sealing members that can deform and adapt to maintain liquid-tight seals even when coaxiality deviation occurs. The sealing members are designed to flex and conform to the actual alignment conditions between pipes, allowing the system to tolerate manufacturing imprecisions while maintaining sealing effectiveness throughout the range of axial movement.
3Device complexity
If the flexible expansion joint is designed to be compact, then the device complexity is reduced, but the allowable axial length is limited
Solution Approach 1:
The nested sleeve design allows the flexible expansion joint to achieve extended allowable axial length within a compact overall form factor. When the pipes move apart axially, the inner sleeve extends relative to the outer sleeve, effectively increasing the functional length without requiring the entire device to be physically long. This nesting approach maintains compact construction while providing the needed movement capability.
Solution Approach 2:
The patent employs dynamic axial movement capability where the inner and outer sleeves can slide relative to each other along the axial direction. This dynamic configuration allows the device to extend its effective length on demand when needed for pipe movement, while maintaining a compact retracted state when not in use. The length limiters provide controlled extension without requiring the device to be permanently extended.
Data Source
AI summary
A flexible expansion joint is capable coping with a great extension for its limited length. The flexible expansion joint includes: a first sleeve to be put on an end part of a first pipe; an outer sleeve to be put on an end part of a second pipe so as to overlap the first sleeve and capable of moving axially relative to the first sleeve; a first sealing member; a second sealing member; a third sealing member; a first length limiter including a first stopper for limiting the axial movement of the first pipe and the first sleeve relative to each other; and a second length limiter including a second stopper for limiting the axial movement of the second pipe the outer sleeve relative to each other.