Reinforced Sealing Ring Assembly for High-Pressure Graphite Seals
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Solution Overview
Problem
Piston sealing rings made from self-lubricating materials like graphite experience high wear rates and tensile stress issues, leading to potential fracture due to the absence of lubrication, which limits their operational lifespan in piston-cylinder devices.
Innovation Solution
A sealing ring assembly with a reinforcement, such as a metal layer or wire, is affixed to the ceramic or polymer ring segments, providing a compressive preload and matching thermal expansion coefficients to reduce tensile stress and enhance durability, allowing for longer operational hours without oil lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-lubricating material like graphite or ceramic is used for the seal, then scuffing and galling are eliminated, but the wear rate increases significantly compared to oil-lubricated metal rings
Solution Approach 1:
The patent applies composite materials by combining a brittle sealing ring material (graphite or ceramic) with a tensile reinforcement material (metal layer, mesh, or fabric). This composite structure allows the seal to benefit from the self-lubricating properties of graphite/ceramic while the metal reinforcement compensates for the low tensile strength, enabling the seal to withstand repeated stretching cycles without fracturing.
2Reliability
If the seal is made from a brittle material weak in tension, then it provides good sealing properties, but it can only withstand a finite amount of stretch before tensile stresses cause fracture
Solution Approach 1:
The patent combines brittle sealing material with tensile reinforcement materials (metal layers, mesh, or fabric) to create a composite structure where the reinforcement carries the tensile loads during stretching, allowing the brittle material to maintain its sealing properties without fracturing.
Solution Approach 2:
The patent applies reinforcement specifically at the inner radial surface of the sealing ring where tensile stresses are highest during stretching. This localized reinforcement provides strength exactly where needed without compromising the sealing properties of the bulk material.
3Stability of the object's composition
If the reinforcement material has a different coefficient of thermal expansion than the sealing ring, then thermal stress may develop, but matching CTEs complicates material selection
Solution Approach 1:
The patent addresses thermal expansion mismatch by selecting reinforcement materials whose coefficients of thermal expansion are compatible with the sealing ring material, or by designing the reinforcement structure to accommodate differential expansion through geometric design rather than strict material matching.
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 reinforcement structure reduces stress and wear on the sealing ring, extending its operational lifespan by maintaining compressive forces and minimizing tensile stress, even under high-pressure conditions, thus improving the sealing efficiency and durability of the piston-cylinder device.
Implementation Method 1
The reinforcement provides a compressive preload onto the at least one ring segment
Implementation Method 2
the at least one ring segment has a corresponding first coefficient of thermal expansion (CTE), the reinforcement has a corresponding second CTE
Data Source
AI summary
The present disclosure provides a sealing ring assembly having a sealing ring and a reinforcement, configured to seal a high-pressure region from a lower pressure region of a piston and cylinder device. The sealing ring may be segmented, and a metal layer, wire, or other reinforcement may be affixed to the ring. The reinforcement is placed into tension against the sealing ring, which is correspondingly placed into compression. The composite structure of a relatively brittle sealing ring and reinforcement provides for reduced tensile loads in the sealing ring, thus extending life and reducing the likelihood of failure. The brittle portion of the sealing ring assembly may include a polymer or ceramic such as graphite, which is relatively less strong in tension than compression.