Patent ID: 8141345

Claim:
A method for regulating an air/fuel ratio of a combustion process which is operated cyclically and alternatingly with excess air and air deficiency, the method comprising: providing at least one catalytic converter volume arrangement in an exhaust gas path of the combustion process, the volume arrangement having an oxygen reservoir to store exhaust gas oxygen in response to an excess of oxygen and to discharge the stored oxygen in response to an oxygen deficiency; registering an oxygen breakthrough in response to a filled oxygen reservoir, and registering an oxygen deficiency in response to an emptied oxygen reservoir downstream from the catalytic converter by a Nernst lambda sensor; summing the oxygen input into the oxygen reservoir of the catalytic converter volume arrangement in response to an excess of air; summing the oxygen liberated by the oxygen reservoir of the catalytic converter volume arrangement in response to an air deficiency; operating the combustion process in a cyclical sequence in each case, in which at least on average there is an excess of air and subsequently on average there is an air deficiency, until a Nernst lambda sensor situated downstream from the catalytic converter volume arrangement detects an oxygen breakthrough or the oxygen deficiency; correcting, using a difference between the summed oxygen input and the summed liberated oxygen, a lambda control loop circuit, which includes a lambda sensor situated upstream of the catalytic converter volume arrangement; using a variable to aid in determining a fuel inflow to the internal combustion engine for a determination of the oxygen charges into the catalyst volume during the air excess and the oxygen discharges from the catalyst volume during the air deficiency; and forming the variable as a function of a signal of an exhaust gas probe situated upstream from the catalytic converter; wherein the variable includes an input variable for a second control loop, in which the fuel/air ratio is regulated using a time constant that is smaller in comparison than that in a first control loop.