Patent Document ID: 9353664
Application ID: 12992787
Patent Flag: 1

Claim One:
1. A method for operating an exhaust gas treatment system, comprising an SCR catalytic converter for the treatment of an exhaust gas of a motor vehicle internal combustion engine, the method comprising: adding, by a dosing unit controllable by a control unit, an ammonia-containing reducing agent to the exhaust gas; feeding an exhaust gas enriched with ammonia according to the dosing to the SCR catalytic converter; calculating, by a computer model, a model ammonia filling level value for an amount of ammonia stored in the SCR catalytic converter; and calculating, by the computer model, (a) a model dosing rate for the dosing of the reducing agent into the exhaust gas at which a target filling level of ammonia stored in the SCR catalytic converter specified by the computer model is at least approximately achieved based on the model ammonia filling level value, or (b) a target efficiency specified by the computer model for a nitrogen oxide conversion with ammonia stored in the SCR catalytic converter or fed to the SCR catalytic converter is at least approximately achieved, wherein the model dosing rate is corrected by applying a changeable long term adaption factor to a target dosing rate, thereby performing a long term adaption of the model dosing rate, wherein the model ammonia filling level value is corrected by applying a changeable short term adaption factor to the model ammonia filling level to produce a corrected model ammonia filling level, wherein the short term adaption factor is determined based on one or more characteristics associated with a relation between a NOx conversion of the SCR catalytic converter and the model ammonia filling level, and wherein during a duration for which the short term adaption factor is applied to the model ammonia filling level value the corrected model ammonia filling level is used as an assumed actual filling level of ammonia in the SCR catalytic converter, wherein the dosing unit is accessed for emitting the target dosing rate, wherein integrations in successive integration cycles of a presettable length respectively determine a nitrogen oxide raw emission value, a nitrogen oxide pure emission estimated value and a nitrogen oxide pure emission measuring value, and further an adaption characteristic value is determined based on a ratio of (a) a difference of the nitrogen oxide pure emission measuring value and the nitrogen oxide pure emission estimated value to (b) the nitrogen oxide raw emission value, and wherein the adaption characteristic value is used for assessment of a necessity for performing a long term or short term adaption.