Abstract: An internal combustion engine comprises at least two intake valves per cylinder, each of them provided with respective spring return means which push the valve towards a closed position. The intake valves of each cylinder are controlled by a single cam of an engine camshaft, through a single tappet actuated by said cam and through a hydraulic system. The hydraulic system comprises a master cylinder having a piston positively connected to said tappet and two hydraulic actuators respectively associated to the two intake valves and which are both hydraulically connected to a common pressure chamber of said master cylinder. The return spring means associated to the intake valves of one and the same engine cylinder have predetermined loadS and/or rigidities which are different from each other, in such a way that said intake valves have different lift profiles, so as to cause a swirl motion of the air fed into the engine cylinder, which allows to improve the air-fuel mixing.

Abstract: An internal combustion engine comprises at least two intake valves per cylinder, each of them provided with respective spring return means which push the valve towards a closed position. The intake valves of each cylinder are controlled by a single cam of an engine camshaft, through a single tappet actuated by said cam and through a hydraulic system. The hydraulic system comprises a master cylinder having a piston positively connected to said tappet and two hydraulic actuators respectively associated to the two intake valves and which are both hydraulically connected to a common pressure chamber of said master cylinder. The return spring means associated to the intake valves of one and the same engine cylinder have predetermined loadS and/or rigidities which are different from each other, in such a way that said intake valves have different lift profiles, so as to cause a swirl motion of the air fed into the engine cylinder, which allows to improve the air-fuel mixing.