Piston rings serve several important purposes in an engine:
They keep a tight seal on the piston heads to ensure that the combustion chamber is properly sealed, preventing the fuel-air mixture from leaking into the crankcase (sump).
They control the oil by scraping excess oil off the cylinder walls and returning it to the sump, which helps in maintaining proper lubrication and preventing oil from entering the combustion chamber.
They transfer heat from the piston to the cylinder wall, aiding in temperature regulation within the engine.
These functions are crucial for maintaining engine efficiency, preventing oil consumption, and ensuring the proper functioning of the engine.