Patent ID: 8166932

Claim:
A method for use in an electro-hydraulic device for variable actuation of the intake and/or exhaust valves of an internal-combustion engine, the method comprising: the electro-hydraulic device comprising a plurality of engine valves, each engine valve of the plurality of engine valves coupled to a pressurized hydraulic chamber that transmits to the engine valve the movement of a tappet actuated by the camshaft of the engine, and in which said pressurized chamber communicates with an exhaust by means of the solenoid valve; energizing a solenoid valve by applying a constant voltage to displace a movable element of the solenoid valve to pressurize the pressurized hydraulic chamber; de-energizing the solenoid valve by applying a zero voltage to displace the movable element of the solenoid valve to de-pressurize the pressurized hydraulic chamber by communicating the chamber with an exhaust to allow a closure of an engine valve of the plurality of engine valves by a spring; the energizing and de-energizing providing an alternation of phases of charging and discharging of the solenoid corresponding to increases and decreases of current around a substantially constant current value, maintaining each phase at the constant voltage is for a fixed time and terminating each phase at the zero voltage is when the decreasing current reaches a pre-set value; and constantly monitoring the duration of each cycle of a plurality of cycles, each cycle made up of the energizing and the de-energizing; comparing a duration of at least two cycles of the plurality of cycles to each other and to a pre-set threshold value; identifying the instant of reaching of the end-of-travel position as being the instant that separates two successive cycles of the plurality of cycles which differ from each other by a duration greater than the pre-set threshold value.