Abstract: Described herein is a system for controlling a solenoid valve, which includes a driving circuit for driving a solenoid of the solenoid valve and a control unit for controlling the driving circuit. The control unit is configured for generating in the solenoid, during operation of the solenoid valve: first current signal for moving the open/close element from a first position to a second position, which is generated by the external supply network, to which the solenoid is connected; and second current signal, which is generated exclusively as a result of residual magnetism in the magnetic element of the solenoid valve and is activated when the open/close element is still in the aforesaid second position.

Abstract: Described herein is a system for controlling a solenoid valve, which includes a driving circuit for driving a solenoid of the solenoid valve and a control unit for controlling the driving circuit. The control unit is configured for generating in the solenoid, during operation of the solenoid valve: first current signal for moving the open/close element from a first position to a second position, which is generated by the external supply network, to which the solenoid is connected; and second current signal, which is generated exclusively as a result of residual magnetism in the magnetic element of the solenoid valve and is activated when the open/close element is still in the aforesaid second position.

Abstract: An internal-combustion engine includes a three-way, three-position control valve with an inlet communicating with a pressurized-fluid chamber and with a hydraulic actuator of an intake valve, and two outlets communicating, respectively, with the actuator of the other intake valve and with said exhaust channel. The control valve has a first position, in which the inlet communicates with both of the outlets, a second position, in which the inlet communicates only with the outlet connected to the actuator of an intake valve and does not communicate, with the outlet connected to the exhaust channel, and a third position, in which the inlet does not communicate with the two outlets. The control valve has an electric actuator supplied only at three different values of electric current to bring the valve into the three positions.

Abstract: A method controls a valve-control system for variable-lift actuation of the valves of an internal-combustion engine, in which the valve-control system includes, for each cylinder of the engine, a solenoid valve for controlling the flow of a hydraulic fluid in the system, and designed manner for determining a real temperature value of the hydraulic fluid. The method includes determining a deviation of performance of the solenoid valves due to a degradation of the characteristics of the hydraulic fluid with respect to nominal values thereof, and substituting for the real temperature value an equivalent temperature value consisting of a temperature value at which the hydraulic fluid having nominal characteristics would produce performance of the solenoid valves corresponding to the performance resulting from the deviation so that each solenoid valve is governed as a function of the equivalent temperature value.

Abstract: A method for controlling a valve-control system for variable-lift actuation of the valves of an internal-combustion engine, wherein the valve-control system comprises, for each cylinder of the engine, a solenoid valve for controlling the flow of a hydraulic fluid in the system, and means configured for determining a real temperature value of said hydraulic fluid. The method includes: determining a deviation of performance of the solenoid valves due to a degradation of the characteristics of said hydraulic fluid with respect to nominal values thereof; and substituting for said real temperature value an equivalent temperature value consisting of a temperature value at which the hydraulic fluid having nominal characteristics would produce performance of the solenoid valves corresponding to the performance resulting from the aforesaid deviation so that each solenoid valve is governed as a function of said equivalent temperature value.

Abstract: The movable element of a solenoid valve is displaced by means of application to the solenoid of alternating phases at constant voltage and at zero voltage, so as to give rise to an alternation of phases of charging and discharging of the solenoid (switching), corresponding to increases and decreases of current around a substantially constant current value. The alternating phases at constant voltage and at zero voltage are controlled so that the phase at constant voltage is maintained for a pre-set time and the phase at zero voltage is terminated when the decreasing current reaches a pre-set value. Alternatively, it is possible to envisage that the phase at constant voltage will be terminated when the increasing current reaches a pre-set value and the phase at zero voltage is maintained for a pre-set time, or else again that both the phase at constant voltage and the phase at zero voltage will be terminated when the increasing current or decreasing current reaches a pre-set value.

Abstract: In an internal-combustion engine equipped with an electronically controlled hydraulic system for variable actuation of the inlet and/or exhaust valves of the engine, the hydraulic system for actuation of the valves includes, for each engine valve, a solenoid valve for controlling the corresponding hydraulic actuator. Each solenoid valve is controlled according to a pre-set control criterion according to the operating parameters of the engine, said pre-set control criterion corresponding to reference operating conditions of the hydraulic fluid and, in particular, to the value of viscosity of the hydraulic fluid, which varies with temperature. The aforesaid control criterion is, however, adjusted according to an estimated deviation between reference operating conditions of the hydraulic fluid and actual operating conditions of the hydraulic fluid.

Abstract: In an internal-combustion engine equipped with an electronically controlled hydraulic system for variable actuation of the inlet and/or exhaust valves of the engine, the hydraulic system for actuation of the valves includes, for each engine valve, a solenoid valve for controlling the corresponding hydraulic actuator. Each solenoid valve is controlled according to a pre-set control criterion according to the operating parameters of the engine, said pre-set control criterion corresponding to reference operating conditions of the hydraulic fluid and, in particular, to the value of viscosity of the hydraulic fluid, which varies with temperature. The aforesaid control criterion is, however, adjusted according to an estimated deviation between reference operating conditions of the hydraulic fluid and actual operating conditions of the hydraulic fluid.