Magneti Marelli

Marco Violani

Luca Poggio

Marco Secco

Giovanni Gaviani

A device for controlling the air/fuel ratio of the mixture supplied to an endothermal engine, in which a first and a second oxygen sensor disposed along an exhaust duct of the engine upstream and, respectively, downstream of a catalytic converter generate a first and respectively a second signal representative of the stoichiometric compositions of the combusted gases, the device having a first control circuit receiving as input the first signal and generating a correction parameter adapted to be applied to a quantity of fuel calculated in an open loop in order to obtain a corrected quantity of fuel for an injection unit of the engine, the device having a second control circuit which receives the second signal, supplies a correction signal to the first circuit in order to modify the correction parameter and has a control branch adapted to sample the second signal at a predetermined time frequency and to vary the correction signal when the difference between two successively sampled values is greater than a predetermined threshold so as to modify the air/fuel ratio and to minimise the time in which the catalytic converter operates at low efficiency.

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Florence, Italy

Marco Violani