There are two types of piston rings: gas ring and oil ring. The function of the gas ring is to ensure the tight sliding fit of the piston and the cylinder liner, to prevent high temperature and high pressure gas from leaking into the crankcase, and to dissipate most of the heat on the top of the piston through the cylinder wall. The function of the oil ring is to distribute and scrape oil. When the engine is running, the lubricating oil of the crankcase is thrown onto the cylinder wall by the parts.
When the piston goes up, the oil ring evenly distributes the lubricating oil on the cylinder wall to facilitate lubrication; when the piston goes down, the oil ring scrapes off the excess lubricating oil on the cylinder wall to prevent the oil from escaping into the combustion chamber.
There are multiple oil return rings in the concave annular groove around the oil ring, and the oil scraped by the oil ring flows back to the crankcase through the radial oil return hole at the bottom of the oil ring groove.
The piston ring has a slit and is elastic. When the piston reciprocates, the piston ring is attached to the cylinder wall, or opens or shrinks to ensure that the top of the plug and the cylinder form a closed space.
There are also 3 piston rings, the first and the second are 180°, and the second and the third are 90°.
