Patent ID: 7926333

Claim:
A method for determining the oxygen storage capacity of a catalytic converter for a motor vehicle using the signals of an oxygen probe upstream and an oxygen probe downstream from the catalytic converter, comprising: determining a delay time which is dependent on the oxygen storage capacity between the signal of the oxygen probe upstream and the signal of the oxygen probe downstream from the catalytic converter, determining a phase shift which is dependent on the oxygen probe dynamics between the signal of the oxygen probe upstream and the signal of the oxygen probe downstream from the catalytic converter, and correcting the determined delay time between the signal of the oxygen probe upstream and the signal of the oxygen probe downstream from the catalytic converter by the determined phase shift, wherein the phase shift for a certain voltage value of the signal of the oxygen probe measured downstream from the catalytic converter in the region in which the signal of the oxygen probe downstream is at least more or less proportional to the filling of an oxygen storage reservoir of the catalytic converter, is determined by determining the two times assigned to this voltage value before and after switchover of the operation of the motor vehicle between rich and lean operation, determining a first difference amount as the difference amount of the two times and cutting this first difference amount in half, determining a second difference amount as the difference amount of the time assigned to the voltage value after switchover and the switchover time, and computing the phase shift as the difference of the second difference amount and the first difference amount which has been cut in half.