Fuel injection device for an internal combustion engine

Claim 1

A fuel injection device for injecting a controlled amount of fuel into an air inlet passage to a cylinder of a spark ignition type internal combustion engine, said fuel injection device comprising: pressure detector means for detecting a pressure within the air inlet passage to the cylinder of the internal combustion engine, said pressure detector means outputting a pressure data corresponding to the detected pressure; pressure variation determining means, coupled to said pressure detector means, for determining a variation of the pressure data over a length of time; load condition judgement means for determining a load condition of the internal combustion engine; threshold level selecting means, coupled to said load condition judgement means, for selecting, in accordance with the load condition of the internal combustion engine determined by the load condition judgement means, a threshold level of the pressure variation determined by the pressure variation determining means; comparator means for comparing said pressure variation determined by said pressure variation determining means, with said threshold level selected by said threshold level selecting means; transient increase calculation means, coupled to said comparator means, for calculating a transient increase of an amount of fuel that is to be injected by the fuel injection device, in accordance with the result of the comparision effected by said comparator means; averaging means for taking an average of a plurality of pressure data outputted from said pressure detector means over an interval of time; pressure data selector means, coupled to said pressure detector means, averaging means, and said transient increase calculation means, for selecting, in accordance with the transient increase of the amount of fuel calculated by said transient increase calculation means, either the averaged pressure data determined by said averaging means or the pressure data currently outputted from said pressure detector means; fundamental amount calculating means, coupled to said pressure data selecting means, for calculating a fundamental amount of fuel that is to be injected by the fuel injection device, wherein the calculation of the fundamental amount of injected fuel is based on a pressure value selected by said pressure data selector means; adder means, coupled to said transient increase calculation means and fundamental amount calculation means, for adding said transient increase of the amount of fuel and the fundamental amount of fuel, thereby obtaining a total amount of fuel that is to be injected by the fuel injection device; and fuel injector means, coupled to said adder means, for injecting the fuel into the air inlet passage to the cylinder of the internal combustion engine, in a controlled amount equal to the total amount of fuel obtained by said adder means.