Patent ID: 7059284

Claim:
A multi-cylinder internal combustion engine, comprising: at least one intake valve and at least one exhaust valve for each cylinder, each provided with respective elastic return means which bias the valve towards a closed position, to control respective intake and exhaust conduits, at least a camshaft, for actuating the intake valves and the exhaust valves of the engine cylinders by means of respective tappets, in which at least each intake valve has variable actuation, being actuated by the respective tappet, against the action of the aforesaid elastic return means, by the interposition of hydraulic means including a pressurised fluid chamber, into which projects a pumping piston connected to the tappet of the intake valve, said pressurised fluid chamber being able to be connected by means of a solenoid valve with an exhaust channel, in order to uncouple the variable actuation valve from the respective tappet and cause the rapid closure of the valve by effect of the respective elastic return means, electronic control means for controlling each solenoid valve in such a way as to vary the time and travel of opening of the variable actuation valve as a function of one or more operative parameters of the engine, in which the aforesaid hydraulic means further comprise an actuator unit for the variable actuation valve, which includes: an actuating piston slidably mounted within a guide bushing, said actuating piston facing a variable volume chamber communicating with the pressurised fluid chamber both through first communication means controlled by a check valve which allows only the passage of the fluid from the pressurised fluid chamber to the variable volume chamber, and through second communication means which allow the passage between the two chambers in both directions, and hydraulic braking means able to cause a narrowing of said second communication means in the final phase of closure of the engine valve, wherein said actuating piston which is a part of said actuator unit of the variable actuation valve has its axis distanced from the axis of the valve and controls said valve through a mechanical transmission.