Method for regulating a filling of a reservoir of a catalytic converter for an exhaust gas component as a function of an aging of the catalytic converter

A control unit configured to regulate, during operation of an internal combustion engine, a filling of an exhaust gas component reservoir of the catalytic converter in the exhaust of an internal combustion engine, the control unit configured to:

• provide, to a first catalytic converter model, in addition to further signals, signals of a first exhaust gas probe to ascertain, using the first catalytic converter model, an actual fill level of the exhaust gas component reservoir, wherein the first exhaust gas probe projects into an exhaust gas flow upstream from the catalytic converter and detects a concentration of an exhaust gas constituent;
• calculate a lambda setpoint;
• convert a predetermined fill level setpoint into a baseline lambda setpoint;
• ascertain and process, using a fill level regulation system, a deviation of the actual fill level from the predetermined fill level setpoint, to yield a lambda setpoint correction value;
• calculate a sum from the baseline lambda setpoint and the lambda setpoint correction value;
• use the sum to calculate a correction value, and correct, using the correction value, a metering of fuel to at least one combustion chamber of the internal combustion engine;
• determine an aging state of the catalytic converter;
• allocate to the aging state a set of model parameters of the first catalytic converter model;
• and
• ascertain each of the model parameters of the set of model parameters of the first catalytic converter model by interpolation from basic values of model parameters, the basic values having been determined for at least two different aging states of a second catalytic converter of identical design as the catalytic converter.