FIELD: mechanical engineering; internal combustion engines. SUBSTANCE: proposed engine has housing, cylinder block, cylinder head, engine cylinder with piston, combustion chamber in cylinder head, intake and exhaust valves installed in cylinder head, and accumulation space arranged in cylinder head and communicating at one side with air or working mixture pressure source and at other side, with combustion chamber. Engine has movable cylinder arranged in combustion chamber, and movable cylinder actuating mechanical. One of bottom of movable cylinder is coupled with rod connected with movable cylinder actuating mechanism. Inlet hole communicating with accumulation space and bypass hole are made in bottoms of movable cylinder. Combustion chamber is limited by cylinder head, outer surface of movable cylinder and piston. Intake valve is arranged inside combustion chamber for movement and periodically overlapping bypass hole of movable cylinder. Intake valve is made for disconnecting combustion chamber and accumulation space in process of combustion, and for subsequent combined movement, together with movable cylinder, into combustion chamber in direction of piston bottom dead center after termination of working stroke and overlapping if bypass hole by intake valve. Intake valve stops together with movable cylinder in process of exhaust when exhaust valve is open. Simultaneously movable cylinder space before intake valve is filled up. With piston moving towards top dead center, movable cylinder can shift towards piston top dead center when intake valve is stopped. At this time accumulation space communicates with combustion chamber through bypass hole. Intake valve can move towards movable cylinder and overlap bypass hole after stopping of movable cylinder. Movable cylinder can change volume of combustion chamber, depending on mode of operation of engine. EFFECT: improved efficiency of operation of two-stroke engine. 4 cl, 5 dwg
