Abstract: In a two-stroke internal combustion engine with a compression-ignition of Diesel type, the exhaust valve or valves (10) are so arranged as to allow flow on at least the major part of their periphery; the piston (3) cooperates with the ceiling of the cylinder head (6) in such manner as to leave, in the vicinity of top dead center, only the required operational clearance between the piston (3) and the part of the ceiling of the cylinder head in which the exhaust valve or valves (10) is or are placed; and a cylindrical recess (14) in which is placed the head (13) of the inlet valve or valves (8) and into which a fuel injector discharges, is arranged in such manner as to constitute practically alone the combustion chamber (7) when the piston (3) is in the vicinity of top dead center.

Abstract: The two-stroke cycle engine employing intake and exhaust valves comprises a combustion and scavenging prechamber having substantially a shape of revolution about an axis and provided with an intake valve seat. Deflecting means or vanes are disposed inside the intake pipe as directly as possible on the upstream side of the seat so as to urge the mass of air into the combustion chamber in the manner of a whirl.