Patent ID: 8180554

Claim:
A method for reducing a difference of normalized air-fuel ratios of various cylinders compared with an objective value of the normalized air-fuel ratio in an internal combustion engine having a plurality of cylinders, injectors, a device to generate ionization current and the signal thereof for each cylinder, a control unit for said engine comprising electronic means suitable to generate a signal representing the normalized air-fuel ratio in each cylinder of said engine on the basis of the ionization current signal, electronic means suitable to verify the constant number of revolutions of said engine on the basis of the ionization current signal, electronic means suitable to verify constant torque delivered by said engine on the basis of the ionization current signal, electronic means suitable to verify the constant normalized air-fuel ratio in each cylinder of said engine on the basis of the ionization current signal, and electronic means suitable to generate an electronic signal representing the quantity of air present in each cylinder, said method comprising: continuative application of a low-pass filter to the normalized air-fuel ratio signal of each cylinder of said engine to obtain a Filtered Cylinder Lambda signal for each cylinder; continuative calculation of a difference between a predetermined signal representing a value between 0.7 and 1.1 and the Filtered Cylinder Lambda signal of each cylinder to obtain a Cylinder Error Lambda signal for each cylinder; registering the Cylinder Error Lambda signal of each cylinder as a Registered Cylinder Error Lambda signal starting from the first engine cycle at each ignition of said engine; sending a signal to each injector to increase the quantity of fuel put into the relevant cylinder in which the Registered Cylinder Error Lambda signal is a negative value; and sending a signal to each injector to decrease the quantity of fuel to admit to the relevant cylinder in which the Registered Cylinder Error Lambda signal is a positive value.