Cryogenic Piston Ring Segmentation to Minimize Leak Paths
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Solution Overview
Problem
Traditional piston ring designs for cryogenic applications suffer from direct leak paths due to thermal contraction, rotation during operation, and wear, leading to reduced sealing capability and performance.
Innovation Solution
A set of dissimilarly shaped piston rings and an expander ring are used to form a hollow cylindrical shape, with the expander ring maintaining contact with the bore surface and the piston rings' unique shapes minimizing leak paths through pressure loading and cooperative design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional piston ring designs are used in cryogenic applications, then the initial sealing capability is adequate, but direct leak paths develop due to thermal contraction, rotation, and wear over time
Solution Approach 1:
The piston ring is divided into multiple circumferential segments rather than being a continuous ring. This segmentation allows each segment to independently accommodate thermal contraction and rotation while maintaining sealing contact with the bore surface, preventing the development of direct leak paths during service
Solution Approach 2:
The piston ring incorporates a flexible expander mechanism that provides continuous outward force to maintain contact between the ring segments and the bore surface. This dynamic adjustment compensates for thermal contraction and wear, ensuring consistent sealing capability throughout the service life
2Reliability
If piston rings are designed to maintain continuous contact with the bore surface, then sealing is improved, but the rings are subject to increased wear and thermal contraction
Solution Approach 1:
Dividing the ring into segments reduces the cumulative wear and thermal stress on any single continuous structure, allowing each segment to independently accommodate dimensional changes while maintaining contact
Solution Approach 2:
The ring material and geometry are designed to accommodate cryogenic temperature parameters, with the expander mechanism providing compensating force that offsets thermal contraction effects throughout the temperature cycle
3Device complexity
If a single continuous piston ring is used, then the structure is simple, but direct leak paths form due to rotation and thermal effects
Solution Approach 1:
The circumferential segmentation of the piston ring, while increasing structural complexity, eliminates the formation of direct leak paths by allowing independent movement of each segment, thereby improving sealing reliability in cryogenic applications
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 effectively reduces direct leak paths and maintains sealing even as the rings wear and shrink, improving the performance of cryogenic pumps by ensuring continuous contact and minimizing fluid leakage.
Implementation Method 1
an expander ring are used to form a hollow cylindrical shape, with the expander ring maintaining contact with the bore surface
Implementation Method 2
Traditional piston ring designs for cryogenic applications suffer from direct leak paths due to thermal contraction
Data Source
AI summary
A piston ring set of a cryogenic pump includes a first piston ring and a second piston ring which are dissimilarly shaped and cooperatively shaped to form a hollow cylindrical shape when in abutment to one another. The first piston ring is C-shaped and defines a middle portion disposed between a first end portion and a second end portion. A piston ring gap is disposed between a first distal end of the first end portion and a second distal end of the second end portion. When the first piston ring is in abutment with the second piston ring forming the hollow cylindrical shape, the second piston ring does not extend along the middle portion of the first piston ring while the second piston ring does extend along the first end portion and second end portion of the first piston ring.