In modern gasoline engines, a scraper ring with a step recessed from the lower outer edge has become a common design for the second ring in a piston-ring pack.
Although previous study suggested that a scraper ring step can provide a reservoir for oil , the effect of its geometry and dimensions on oil transport and oil consumption has not been completely understood.
In this work, an oil transport mechanism that is closely associated with the dimensions of a scraper ring step will be described.
Particularly, oil can be trapped in a scraper ring step and the trapped oil can result in bridging.
Each simulation started with an arbitrary oil distribution in a scraper ring step and on a third land.
The engine was disassembled: three piston skirts were broken, the bottom scraper ring
from each broken piston was found in the oil sump.