Method for determining actual mean value of oxygen filling of exhaust catalytic converter involves providing assumed mean value with reference value of voltage signal

摘要

The method involves assigning to an assumed mean value of the oxygen filling a reference value of the voltage signal of a binary lambda probe disposed in the area of the catalytic converter. A symmetric modulation of the lambda regulation is undertaken to vary the voltage signal within the constant range between a lower threshold value and an upper threshold value. The variation in the voltage signal in respect of the reference value is evaluated for symmetry and the actual mean value is determined from the assumed mean value of the oxygen filling and from the symmetry evaluation of the voltage signal. The lambda regulation of the engine is adapted to the previously determined actual mean value of the oxygen filling of the catalytic converter.