Method and device for regulating an air-fuel ratio of an internal combustion engine

Abstract

The invention relates to a method and to a regulating device for regulating an air-fuel ratio of an internal combustion engine (), wherein an exhaust-gas composition of an exhaust gas of the internal combustion engine () is determined by virtue of an actual probe signal, which is dependent on the exhaust-gas composition, being detected by means of an exhaust-gas probe () and the exhaust-gas composition being determined as a function of the actual probe signal by means of a characteristic curve or a calculation rule, and wherein the determined exhaust-gas composition is compared with a setpoint value or a threshold value, the attainment or exceedance of which triggers a manipulation of the air-fuel ratio supplied to the internal combustion engine (), wherein, in order to take into consideration at least one disturbance variable which affects the actual probe signal, a safety margin (ΔS) is defined which is applied to the characteristic curve or calculation rule, to the actual probe signal or to the setpoint value or threshold value. It is provided that an evaluation of a present accuracy of the at least one disturbance variable and/or of a present influence of the at least one disturbance variable on the probe signal is performed, and the safety margin (ΔS) owing to the at least one disturbance variable is defined as a function of the evaluation.