FIELD: mechanical engineering. SUBSTANCE: in operation of the engine during the stroke of sucking fresh charge and stroke of discharging combustion products the volume of the combustion chamber is varied. When fresh charge is fed the working fluid is compressed in the auxiliary cylinder connected with a source of high pressure. Then the combustion products are discharged and the auxiliary working fluid is expanded. The internal combustion engine has piston kinematically connected with the engine shaft, arresters, and source of high pressure. The piston is mounted inside the cylinder to define under- piston space which is in communication with the high pressure source through the crankcase. The arresters are rigidly secured to the walls of the cylinder at the bottom. EFFECT: enhanced efficiency. 3 cl, 2 dwg
