Fuel injection device for an internal combustion engine

Abstract

A fuel injection device for an automotive spark ignition internal combustion engine provided with a supercharger is disclosed, wherein the amount of fuel injected in synchrony with the crank angle signal is determined on the basis of the intake air pressure. The increment of the air pressure data over each fuel injection period is compared with a first threshold level to determine the first augmentation. The pressure data is averaged over each fuel injection period, and the increment of the averaged pressure data over a predetermined interval of time is compared with a second threshold level to determine the second augmentation. The fundamental amount is calculated on the basis of either the instantaneous or the averaged pressure data, in dependency on the value of the first augmentation amount. The total amount of fuel that is to be injected in synchrony with every predetermined numberth pulse of the crank angle signal is calculated in each injection cycle as a sum of the fundemental amount and the first and the second augmentation when the engine is judged to be in the supercharged state; when, on the other hand, the engine is judged to not to be in the supercharged state, the total amount of fuel is calculated as the sum of the fundamental amount and the first augmentation alone. The supercharged state is detected when both the intake air pressure and the number of rpm of the engine are above respective predetermined levels.