FIELD: mechanical engineering: four-stroke internal combustion engines. SUBSTANCE: proposed device contains cylinder, piston, cylinder head with intake and exhaust valves, movable undervalve cup, camshaft with cam mechanism to operate intake and exhaust valves and drive mechanism of undervalve cup. Undervalve cup is provided with seats for intake and exhaust valves and it has intake and exhaust channels and intake and exhaust ports. Upper end face surface of undervalve cup is provided with guide rod, holes for valve steams and hole connecting intake channel of undervalve cup with space between upper end face surface of undervalve cup and bottom of hole of undervalve cup. Combustion chamber is formed by piston crown, bottoms of undervalve cup, intake and exhaust valves and walls of hole of undervalve cup. At minimum loads of engine and at starting, undervalve cup shifts towards piston, thus providing minimum volume of combustion chamber, maximum compression ratio, minimum travel of intake valve and minimum charge (air or fuel-air mixture). At increase of engine load, undervalve cup shifts to side opposite to piston under action of spring, thus increasing volume of combustion chamber, decreasing compression ratio and increasing stroke of intake valve and amount of working charge taken-in, and clearance compensators decrease value of clearance. At nominal load of engine, undervalve cup shifts into extreme upper position relative to piston, thus providing increase of volume of combustion chamber, travel of intake valve and amount pf working charge to maximum and decrease of compression ratio to minimum, with clearance compensator being set to minimum clearance. EFFECT: increased efficiency, reduced fuel consumption, improved performance of engine and reliability of device. 24 cl, 4 dwg
