The functions of the piston ring include four functions: sealing, regulating oil (oil control), heat conduction (heat transfer), and guiding (support). Sealing: refers to sealing the gas, preventing the gas in the combustion chamber from leaking into the crankcase, controlling the leakage of the gas to a minimum, and improving the thermal efficiency.
Air leakage will not only reduce the power of the engine, but also deteriorate the oil, which is the main task of the air ring; Adjust the oil (oil control): scrape off the excess lubricating oil on the cylinder wall, and at the same time make the cylinder wall thin The thin oil film ensures the normal lubrication of the cylinder, piston and ring, which is the main task of the oil ring. In modern high-speed engines, special attention is paid to the role of the piston ring to control the oil film; heat conduction: the heat of the piston is transferred to the cylinder liner through the piston ring, that is, cooling.
According to reliable data, 70-80% of the heat received by the piston top in the non-cooled piston is dissipated through the piston ring to the cylinder wall, and 30-40% of the cooled piston is transmitted to the cylinder through the piston ring Support: The piston ring keeps the piston in the cylinder, prevents the piston from directly contacting the cylinder wall, ensures the smooth movement of the piston, reduces frictional resistance, and prevents the piston from knocking the cylinder. Generally, the piston of gasoline engine uses two air rings and one oil ring, while diesel engine usually uses two oil rings and one air ring.
