Coupling Seal Structure for Cryogenic Temperature Cycling
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Solution Overview
Problem
Couplings face challenges in maintaining sealing performance, especially with low-temperature fluids like liquid nitrogen, liquid oxygen, and liquid hydrogen, due to deterioration from temperature cycling, which affects both the inner and outer protrusions in existing seal structures.
Innovation Solution
A seal structure with an annular gasket and specific protrusions on the coupling members, where the second surface protrudes more and presses against the gasket, ensuring sealing performance by biting into the gasket, even as the inner side protrusion's performance decreases with temperature cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an annular gasket with two identical protrusions is used for sealing, then initial sealing performance is achieved, but sealing performance deteriorates during temperature cycling under low-temperature conditions
Solution Approach 1:
The patent applies asymmetry by providing two different annular protrusions: a first annular protrusion and a second annular protrusion with a greater protruding amount. This asymmetric design ensures that during temperature cycling, when the inner-side first protrusion's sealing performance decreases, the outer-side second protrusion with greater protruding amount maintains effective sealing contact with the gasket, thereby resolving the contradiction between initial sealing performance and sealing performance stability during temperature cycling.
2Reliability
If packing is used as a seal member in check valve mechanisms, then sealing is achieved, but sealing performance deteriorates when used for low-temperature fluids
Solution Approach 1:
The patent applies parameter changes by modifying the protruding amount parameter of the annular protrusions. The second annular protrusion is designed with a greater protruding amount than the first, creating a differential sealing structure. This parameter change enables the sealing structure to adapt to low-temperature conditions where material contraction occurs, ensuring that at least one protrusion maintains effective sealing contact with the gasket across a wide temperature range.
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 seal structure maintains long-term sealing performance during temperature cycling by the second surface's increased biting action, preventing a decrease in sealing efficiency, even when the inner side protrusion's performance diminishes.
Implementation Method 1
at least the second surface pressing against the gasket
Implementation Method 2
the first protrusion and the second protrusion digging into the gasket
Data Source
AI summary
Provided are a seal structure in which sealing performance is ensured over a long period of time even when it is used for low-temperature fluids, a sealing method, and a coupling including the seal structure. The seal structure includes an annular gasket interposed between a first member and a second member. The first member is provided on its surface facing the gasket with: a first surface located on the inner diameter side; a first annular protrusion located on the outer diameter side of the first surface; a second surface located on the outer diameter side of the first protrusion; a second annular protrusion located on the outer diameter side of the second surface and having a greater protruding amount with respect to the second surface than that of the first protrusion; and a third surface located on the outer diameter side of the second protrusion.