FIELD: mechanical engineering; four-stroke internal combustion engines. SUBSTANCE: proposed method to control volume of combustion chamber is designed for internal combustion engine containing cylinder, piston, cylinder head with cylindrical cavity for undervalve cup with holes to let in air and let out exhaust gases, movable undervalve cup with intake and exhaust valves and camshaft with valve drive cam mechanism. Variable-volume combustion chamber is formed by undervalve cup together with intake and exhaust valves, walls of cavity of undervalve cup and piston crown. With engine operating at nominal power, maximum volume of combustion chamber is set owing to position of undervalve cup with valves in upper remote from piston point, thus providing minimum compression ratio. With engine operating at partial loads, volume of combustion chamber is decreased by shifting undervalve cup with valves towards piston. Decreased volume of combustion chamber is set basing on relationship between maximum volume of combustion chamber and decreased volume of combustion chamber directly proportional ratio of cylinder fill factor at nominal power to fill factor at partial loads and inreversely proportional to ratio of compression ratio at engine nominal power to compression ratio at engine partial loads. With engine operating at minimum load, volume of combustion chamber is decreased to minimum value by shifting under-valve cup to point close to piston. Minimum volume of combustion chamber and maximum compression ratio are set basing of relationship between maximum volume of combustion chamber and minimum volume of combustion chamber directly proportional to ratio of cylinder fill factor at nominal power to fill factor at minimum load and inreversely proportional compression ratio at engine nominal power to compression ratio at engine minimum load. EFFECT: increased efficiency of engine, reduced fuel consumption and improved engine performance. 1 dwg
