Radially Notched Piston Rings for Engine Sealing
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Solution Overview
Problem
Conventional annular seals in internal combustion engines face issues with excessive friction, vibration, wear, and uneven tension, leading to fluid leakage, power loss, and poor fuel economy due to their inherent tendency to expand and maintain high tension against the cylinder sidewall.
Innovation Solution
A tensionable annular piston ring with radially notched inner surfaces, where the notches are spaced along the length to relieve tension and prevent crack propagation, providing a constant or variable tension-relieving property to minimize wear and maintain even pressure, thus reducing friction and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional piston rings are used with end gaps, then installation is facilitated and thermal expansion is accommodated, but fluid leakage (blow-by) increases and sealing efficiency deteriorates
Solution Approach 1:
The piston ring is segmented into multiple sections with notches created at specific locations. These notches divide the continuous ring structure into manageable segments that can be installed more easily while maintaining sealing effectiveness. The segmentation allows the ring to be installed with reduced end gap issues while preserving the sealing function across the entire circumference.
2Strength
If piston rings are made of heavier construction (cast iron), then durability and wear resistance improve, but friction against cylinder sidewall increases and fuel economy deteriorates
Solution Approach 1:
The piston ring incorporates local quality variations through strategically placed notches that create zones of different mechanical properties. The notched regions have reduced material density and altered stress distribution characteristics compared to the solid portions. This local modification reduces overall friction while maintaining wear resistance in critical sealing areas, resolving the contradiction between durability and energy loss.
3Reliability
If piston rings maintain high tension against cylinder sidewall, then sealing performance improves, but friction increases and fuel economy deteriorates
Solution Approach 1:
The notched piston ring design creates a dynamic tension distribution pattern where the notches allow the ring to flex and adjust its tension characteristics. Rather than maintaining uniformly high tension throughout, the notched regions create variable tension zones that adapt to operating conditions. This dynamic behavior maintains adequate sealing pressure where needed while reducing friction in other areas, improving fuel economy without sacrificing sealing performance.
4Reliability
If end gap is eliminated in piston rings, then blow-by is reduced and sealing is improved, but manufacturing complexity increases and installation becomes difficult
Solution Approach 1:
The notches are pre-formed during the manufacturing process at specific locations around the piston ring circumference. This preliminary action of creating notches during manufacturing prepares the ring for easier installation and reduces the complexity of achieving proper fit. The pre-positioned notches serve as installation guides and stress relief points, making the otherwise complex task of eliminating end gaps while maintaining sealing effectiveness much more manageable.
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 radially notched piston ring effectively reduces fluid leakage, improves fuel economy, and extends the operational life of the engine by minimizing wear and maintaining a consistent seal, even under extreme heat conditions.
Implementation Method 1
annular member tension-relieving notches formed in the inner surface of the annular member, the notches are spaced-apart along the length of the annular member between the first end and the second end, and each notch has a blunt notch tip for inhibiting crack propagation in the annular member from the blunt notch tip
Implementation Method 2
The end gap also allows for thermal expansion of the piston ring resulting from heat generated by friction, compression of fluid, combustion of fuel and other sources.
Implementation Method 3
Having an inherent tendency to expand, the ring maintains constant tension for attendant sealing against the sidewall of the cylinder as the bore increases in diameter as a result of wear.
Data Source
AI summary
In an annular groove carried by one of a pair of reciprocally movable members, a piston ring is carried by the annular groove for sealing the reciprocally movable members for minimizing fluid leakage between the members. The piston ring is an annular member that includes an outer contact surface engagable with the sidewall, an opposed inner surface, an end gap that severs the annular member and that defines spaced-apart first and second ends of the annular member, and annular member tension-relieving notches formed in the inner surface of the annular member. The notches are spaced-apart along the length of the annular member between the first end and the second end, and each notch has a blunt notch tip for inhibiting crack propagation in the annular member from said blunt notch tip when the annular member is tensioned.