FIELD: mechanical engineering; four-stroke internal combustion engines. SUBSTANCE: proposed device contains cylinder, piston, cylinder head with intake and exhaust valves, movable cylindrical undervalve cup, camshaft with cam mechanism to operate intake and exhaust valves and drive mechanism of undervalve cup to regulate volume of combustion chamber. Device is furnished also with other drive mechanism for cleaning combustion chamber. Undervalve cup has seats for intake and exhaust valves and bushing installed on undervalve cup coaxially to seat of intake valve. Cavity for displacement of bushing is made in cylinder head in intake manifold. Sealing members are installed on outer sides of undervalve cup and bushing, and at least one guide rod is provided on side of undervalve cup opposite to piston. Combustion chamber is formed by piston crown, bottoms of undervalve cup, intake and exhaust valves and walls of hole of under cup. At minimum loads of engine and at starting, undervalve cup shifts towards piston, thus providing minimum volume of combustion chamber and maximum compression ratio. At increase of engine load, under-valve cup shifts to side opposite to piston under action of spring, thus increasing volume of combustion chamber and decreasing compression ratio. At nominal load of engine, undervalve cup shifts to extreme upper position relative to piston, thus providing increase of volume of combustion chamber and decreasing compression ratio to minimum value. EFFECT: increased efficiency of engine, reduced fuel consumption, improved engine performance and reliability of device. 19 cl, 2 dwg
