Combustion chamber for two-stroke reciprocating engine, and and engine making use thereof

A combustion chamber for a reciprocating, two-stroke, controlled-ignition, internal-combustion engine, comprising at least one piston, a cylinder, a cylinder head delimiting said combustion chamber, and admission and exhaust ports at the bottom of the cylinder, via which the components of an inflammable mixture are admitted from two admission devices, air without fuel being admitted via two ports close to the exhaust port and disposed symmetrically thereabout, with the axes of said two ports converging inside the chamber and being directed towards the wall opposite the exhaust port, whereas the mixture containing all of the fuel in air is admitted via at least one port provided in a portion of the cylinder wall which is opposite to the exhaust port, wherein the cylinder head includes a cavity whose portion furthest from the fuel admission port is delimited by a substantially vertical wall, with the axes of the admission devices leading to the abovementioned admission ports being included in such a manner that the admitted flows meet at an angle enabling the fuel-containing flow to be dynamically deflected towards the wall through which it is admitted, and for deflecting the pure air flow towards the bottom edge of the connection between the above-mentioned vertical wall of the cavity and the surface of the cylinder head, said flow of pure air splitting on said edge so as to confine the mixture by means of a counter flow of air in the cavity, and simultaneously scavenge the zone of the combustion chamber adjacent to the exhaust port with pure air, thereby avoiding fuel losses via the exhaust.