What is the function of the oil ring?

[Gabrielle]

The function of the oil ring is to scrape off excess oil from the cylinder wall and spread a uniform oil film on the cylinder wall. This prevents oil from entering the combustion chamber and reduces wear between the piston, piston rings, and cylinder wall. The oil ring is a type of piston ring, divided into two types: conventional oil rings and composite oil rings. The conventional oil ring is typically made of alloy cast iron, with a groove in the middle of its outer surface and many small oil drainage holes or slits at the bottom of the groove. The composite ring consists of upper and lower scraper rings and an expander that provides radial and axial tension. The scraper rings of this type are very thin, exert high specific pressure on the cylinder wall, and have strong oil-scraping capabilities. The upper and lower scraper rings operate independently, offering good adaptability to the cylinder, with low mass and large oil return passages.