Two-cycle internal combustion engine

A two-cycle internal combustion engine comprising a cylinder with a main piston, the cylinder having a port in which an intake valve is placed for feeding a fuel-air mixture from an intake manifold into a first intake chamber which is positioned under the piston, is isolated from a crank chamber and communicates with a combustion chamber positioned above the piston by means of a by-pass manifold, with an intake valve placed at the input of the by-pass manifold for feeding the fuel-air mixture from the intake chamber into the combustion chamber,

• a window for discharging exhaust gases from the combustion chamber, the window being positioned on the wall of the cylinder, characterized in that the engine comprises
• an additional piston arranged in the cylinder between the crank chamber and the main piston and rigidly connected to the main piston,
• a second intake chamber which is positioned between the first intake chamber and the additional piston, is isolated from the first intake chamber by means of a partition and communicates with the intake manifold by means of a valve mounted in a port at the inlet to the second intake chamber and facing with its input the intake manifold, and with the by-pass manifold by means of a valve mounted in a port at the outlet from the second intake chamber and facing with its input the second intake chamber,
• and a valve mounted in the by-pass manifold at the inlet to the combustion chamber and facing with its input the first and second intake chambers, said inlet being at a level allowing fuel introduction into the combustion chamber during the compression stroke.