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, upper end face surface, intake and exhaust channels, intake and exhaust ports. Upper end face surface of undervalve cup has guide rod, for valve steams and hole connecting intake channels 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 valve and wall of hole undervalve cup. At minimum loads of engine and at starting with undervalve cup shifted into extreme lower position towards piston, intake valve displaces through maximum value relative to axis of rotation of camshaft cam, thus providing minimum travel of intake valve and minimum area of through section of opened intake valve. At increase of load on engine, undervalve cup shifts in opposite side relative to piston, thus providing increase of intake valve stroke and area of through section of opened intake valve. At nominal load undervalve cup displaces into extreme upper position relative to piston thus providing maximum stroke of intake valve and maximum area of through section of opened intake valve. EFFECT: increased efficiency of engine, reduced fuel consumption, improved performance of engine and reliability of device. 22 cl, 3 dwg
