SYSTEM AND METHOD FOR VARIABLE ACTUATION OF A VALVE OF AN INTERNAL-COMBUSTION ENGINE, WITH A DEVICE FOR DAMPENING PRESSURE OSCILLATIONS

摘要

A system for variable actuation of an engine valve of an internal-combustion engine includes a master piston and a slave piston, driven by the master piston. A control valve controls a communication of a volume of a pressurized fluid with a lower pressure environment, which is connected to a fluid accumulator, and an electronic control unit controls the electrically operated control valve. A device for dampening pressure oscillations is connected to the volume of pressurized fluid and includes an additional volume adapted for receiving fluid from the volume of pressurized fluid only when, following upon oscillations of the pressure in the volume of pressurized fluid, the pressure exceeds a maximum threshold value, which is higher than a mean pressure value that is set up in the volume of pressurized fluid when the master piston drives the slave piston in normal operating conditions.

主权项

1. A system for variable actuation of an engine valve of an internal-combustion engine, comprising:
a master piston driven directly or indirectly by a cam of a camshaft of the internal-combustion engine; a slave piston, which drives said engine valve and is hydraulically driven by said master piston, by means of a volume of pressurized fluid interposed between the master piston and the slave piston; an electrically operated control valve, which controls a communication of said volume of pressurized fluid with a lower pressure environment, said lower pressure environment being connected to a fluid accumulator; and an electronic control unit for controlling said electrically operated control valve on the basis of one or more parameters indicating the operating conditions of the engine and/or of the system for variable actuation of the engine valve, wherein a device for dampening pressure oscillations in the volume of pressurized fluid is connected to said volume of pressurized fluid, and said oscillation dampening device comprising an additional volume adapted for receiving fluid from said volume of pressurized fluid only when said pressure exceeds a maximum threshold value.