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: An internal-combustion engine with two inlet valves for each cylinder is provided with an electronically controlled system for actuating said valves. The electronic control unit is programmed so as to control in a differentiated way the two inlet valves according to a first law of opening and closing and a second law of opening and closing, which are different from one another. The electronic control means are moreover designed for reversing with respect to one another the laws of opening and closing of the two inlet valves at each operating cycle of the engine or else with a periodicity equal to more than one operating cycle of the engine, so that each of the two inlet valves alternately follows the first law and the second law of opening and closing.

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: An internal-combustion engine with two inlet valves for each cylinder is provided with an electronically controlled system for actuating said valves. The electronic control unit is programmed so as to control in a differentiated way the two inlet valves according to a first law of opening and closing and a second law of opening and closing, which are different from one another. The electronic control means are moreover designed for reversing with respect to one another the laws of opening and closing of the two inlet valves at each operating cycle of the engine or else with a periodicity equal to more than one operating cycle of the engine, so that each of the two inlet valves alternately follows the first law and the second law of opening and closing.