Valve actuating device, and method for controlling same

A device for actuating valves of a motor-vehicle internal combustion engine, in which each valve is provided with a rod or stem integral with an actuator operated by a control unit to bring about lifting and return of an associated of the valves, each actuator being in a form of a hydraulic cylinder provided with a barrel, inside which barrel the stem of the associated valve is free to slide coaxially in a leaktight relationship, and inside which barrel a movable piston is disposed that is integral with a free end of the valve stem and that defines in the barrel two opposite upper and lower hydraulic pressure chambers, each pressure chamber being supplied with an incompressible fluid, and in each of which pressure chamber a pressure of the fluid is alternately established, the pressure being regulated by the control unit such that pressure prevailing in a first one of the chambers is alternately higher or lower than pressure prevailing in a second one of the chambers, to actuate the hydraulic cylinder and the valve alternately,

• wherein each hydraulic pressure chamber of the hydraulic cylinder is configured to be placed in communication with at least one independent respective hydraulic pressure source associated with only the respective chamber and including means for elastic returning of the fluid, the means for elastic returning further for recovering kinetic energy of the associated valve during movement of the associated valve in a particular direction, in view of subsequent movement of the associated valve in a direction opposite to the particular direction.