Asymmetric Piston Ring Oil Stripping Edge Design
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Solution Overview
Problem
Modern internal combustion engines face challenges in minimizing friction losses and oil consumption due to reduced piston ring height and radial contact pressure, leading to potential oil carbon formation and piston ring seizing, especially with asymmetrically barrel-shaped working surfaces which can result in inefficient oil transport away from the combustion chamber.
Innovation Solution
A method involving a piston ring blank with an asymmetrically barrel-shaped contour and a radial projection on the outer mantle surface, coated with wear-resistant materials, where the projection is removed to form a sharp oil stripping edge, ensuring effective oil transport towards the crankcase, and a smooth transition between the coating and upper ring side is maintained through bevel or radius formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the height of piston rings is reduced to minimize friction losses, then friction losses are reduced, but oil consumption increases and oil carbon formation occurs
Solution Approach 1:
The piston ring is designed with an asymmetrically barrel-shaped working surface where only specific regions (the lower ring side and oil stripping edge) have enhanced oil-stripping properties, while other regions maintain sealing functions. This localized functional differentiation allows effective oil control without increasing overall ring height or friction
Solution Approach 2:
The oil stripping edge is positioned at the lower ring side to proactively remove excess oil before it can be transported upward into the combustion chamber. This preliminary action prevents oil from reaching the combustion zone, thereby reducing oil consumption and carbon formation while maintaining reduced ring dimensions
2Loss of energy
If the radial contact pressure of piston rings is reduced to minimize friction losses, then friction losses are reduced, but oil film sealing capability deteriorates and oil consumption increases
Solution Approach 1:
The piston ring features an asymmetrically barrel-shaped working surface with a specifically designed oil stripping edge at the lower ring side. This asymmetric geometry creates effective oil control functionality that compensates for reduced radial contact pressure, allowing the ring to strip excess oil efficiently even with lower overall contact pressure
Solution Approach 2:
The oil stripping edge is designed with specific geometric properties (asymmetric barrel shape) that concentrate oil-stripping functionality in a localized region. This local enhancement of oil control capability compensates for the reduced radial contact pressure across the entire ring surface, maintaining reliable oil film sealing without increasing overall friction
3Reliability
If a symmetrically or asymmetrically barrel-shaped working surface is used to create an oil pressure barrier, then gas sealing is improved, but excess oil transport toward the crankcase becomes inefficient
Solution Approach 1:
The oil stripping edge is positioned at the lower ring side to proactively intercept and remove excess oil during the downward piston movement. This preliminary oil stripping action occurs before oil can be transported upward into the combustion chamber, ensuring both effective gas sealing and efficient oil drainage toward the crankcase
Solution Approach 2:
The working surface is segmented into distinct functional zones: the asymmetrically barrel-shaped region creates the oil pressure barrier for gas sealing, while the separately positioned oil stripping edge at the lower ring side handles excess oil removal. This functional segmentation allows both gas sealing and oil transport to occur independently and effectively
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 method produces a piston ring with a marked oil stripping edge, enhancing oil transport efficiency and reducing the risk of oil carbon formation and seizing, while maintaining a smooth seal against combustion gases, suitable for both gasoline and diesel engines.
Implementation Method 1
coating the outer mantle surface with a coating material
Implementation Method 2
coating the outer mantle surface with a coating material
Data Source
AI summary
The invention relates to a method for producing a piston ring (30, 130, 230) for a piston (10) of an internal combustion engine, comprising a ring back (31), an upper ring flank (32), a lower ring flank (33), and a running surface (42), and the method comprising the following method steps: (a) preparing a ring blank (30′) with a ring back (31′), an upper ring flank (32′), a lower ring flank (33′), and an outer lateral face (34′), (b) shaping an asymmetrical convex contour (35) along the outer lateral face (34′) and shaping a radially outward-extending protrusion (36) in the outer lateral surface (34′) in the region of the lower ring flank (33′), (c) coating the outer lateral surface (34′) with a coating material, (d) removing the protrusion (36), thereby exposing the material of the ring blank (30′) in the shape of a circumferential surface (41) which blends into the coating (39), and forming an oil scraper edge (40) between the circumferential surface (41) and the lower ring flank (33′), and (e) post and/or final processing of the coated ring blank (30′) to obtain a finished piston ring (30, 130, 230).