Internal combustion engine with gasoline direct injection, having a system for variable actuation of the intake valves

摘要

In an internal combustion engine, with gasoline direct injection, provided with a system (11, 15, 16, C, 21, 24, 25) for the variable actuation of the intake valves (7), there are provided for electronic control means (25) for controlling the system for the variable actuation of the intake valves (7) and for controlling gasoline injection into the combustion chamber. To said electronic control means (25) there are associated memory means (M) in which there are memorised, according to different values of the engine rotational speed and according to different values of the engine load, an allowed limit value (SoI) of the crank angle before which gasoline injection cannot start, in that it would give rise to an excessive smoke at the exhaust, and a minimum distance value (”), in terms of crank angle, which should elapse between the end of gasoline injection and the closing of the intake valve, to guarantee a homogeneous mixture of gasoline and air. Said electronic means (25) are programmed for: - detecting, in any operating condition of the engine, the value of the crank angle at which the intake valve (7) is closed, - controlling, in any operating condition of the engine, the end of the injection with an anticipation with respect to the closing of the intake valve (7) which is equivalent to said minimum distance value (”), - controlling, in any operating condition of the engine, the start of the injection substantially according to said crank angle limit value (SoI), and - regulating, in any operating condition of the engine, the injection pressure to a value (P target ) which is defined as a function of the injection time resulting from the abovementioned operations, to guarantee the injection of a predefined amount of gasoline.