Abstract: Internal combustion engine with fuel injection directly into the combustion chamber of the engine. The engine has inlet channels, the angle of incidence (valve angle) (&agr;) of which is greater than 20° relative to the longitudinal axis of the cylinder chamber. The piston tops are made, firstly, with a surface portion inclined relative to a plane normal to the longitudinal axis of the cylinder chamber by an angle (&ggr;) equal to or less than the angle of incidence of the inlet channel, and, secondly, with a cavity connected to the inclined surface portion. By interaction between the angle of incidence of the inlet channels and the shape of the piston tops, there is generated in the combustion chambers a primary vortical movement in the inlet air about an axis perpendicular to the longitudinal axis of the cylinder chamber. The primary vortical movement generates a secondary vortical movement in the opposite direction in the piston cavity.

Abstract: A combustion system for engines having at least one cylinder (10). The system may e.g. consist of an exhaust duct, an intake duct (20a), a cylinder chamber (30), a fuel injector for injecting fuel into the cylinder chamber (30), a piston (40) performing a reciprocating motion in the cylinder chamber (30), and a valve (70) for intake and one for exhaust. The intake duct (20a) is connected to the cylinder chamber (30) and said intake valve (70) is operative to open and close, respectively, the connection between the intake duct (20a) and the cylinder chamber (30). The crown (60) of the piston (40) is provided with a cavity (50), shaped so as to enhance the generation of tumbling inside the cylinder chamber (30) during the intake stroke and to contribute to the breakdown during the compression stroke inside the cylinder chamber (30).