Patent ID: 8096281

Claim:
A diesel engine comprising: at least one intake valve for each cylinder, provided with elastic return means that push the valve towards a closed position; and at least one camshaft for controlling the intake and exhaust valves, by means of respective tappets, wherein at least one intake valve for each cylinder is controlled by the respective tappet, against the action of the elastic means, by interposition of hydraulic means including a pressurized fluid chamber, wherein said pressurized fluid chamber is designed to be connected by means of a passage controlled by a solenoid valve with an exhaust channel, so that when the solenoid valve is open, the intake valve is uncoupled from the respective tappet and is kept closed by said elastic means, there being associated to said engine electronic control means for controlling each solenoid valve in such a way as to vary the time and the stroke of opening of the respective intake valve as a function of the operating conditions of the engine, wherein the cam for controlling said intake valve has a main lobe for causing opening of the intake valve during the induction stroke for intake of fuel into the engine cylinder, and an auxiliary lobe for causing an additional opening of the intake valve during the exhaust stroke, said diesel engine being characterized in that the additional lobe is shaped in such a way as to provide a profile of the additional lift of the intake valve, as the crank angle varies, which is shaped like a boot with an initial portion with gentler slope, which then extends into a second portion having the traditional bell shape, rising with a steeper slope, which terminates in a point of maximum lift, and then descending, said initial portion of the profile of the additional lift of the intake valve extending from an initial point of zero lift corresponding to a crank angle comprised in the expansion stroke in the cylinder.