Piston rings are widely used in various power machinery, such as steam engines, diesel engines, gasoline engines, compressors, hydraulic machines, etc., and are widely used in automobiles, trains, ships, yachts, etc. Generally, the piston ring is installed in the ring groove of the piston, and it forms a chamber with the piston, cylinder liner, cylinder head and other components to perform work. 　　 

The meaning of the piston ring is the core component of the fuel engine. It completes the fuel gas seal together with the cylinder, piston, cylinder wall, etc. Commonly used automobile engines include diesel and gasoline engines. Due to their different fuel performance, the piston rings used are different. Early piston rings were formed by casting, but with the advancement of technology, high-power steel piston rings were born. , And with the continuous improvement of engine functions and environmental requirements, various advanced surface treatment applications, such as thermal spraying, electroplating, chromium plating, gas nitriding, physical deposition, surface coating, zinc-manganese phosphating treatment, etc., The function of the piston ring is greatly improved. 　　 

The functions of the piston ring include four functions: sealing, oil adjustment (oil control), heat conduction (heat transfer), and guidance (support). Sealing: refers to sealing the gas, preventing the gas in the combustion chamber from leaking to the crankcase, controlling the gas leakage to a lower limit, and improving 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 crown in a non-cooled piston is transmitted to the cylinder wall through the piston ring, 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 direct contact between the piston and the cylinder wall, ensures smooth movement of the piston, reduces frictional resistance, and prevents the piston from knocking on the cylinder. Generally, the piston of a gasoline engine uses two gas rings and one oil ring, while a diesel engine usually uses two gas rings and one oil ring.