Method, computing unit, and computer program for operating an internal-combustion engine

A computing unit (140) for operating an internal-combustion engine (120) with an exhaust gas aftertreatment system including an exhaust gas catalyst (130), at least a first exhaust gas sensor (145) arranged upstream of the exhaust gas catalyst (130), and at least a second exhaust gas sensor (147) arranged downstream of the exhaust gas catalyst (130), the computing unit configured to:

• sense (210) at least one signal of the first exhaust gas sensor (145) as a first signal indicative of at least one exhaust gas component,
• determine (220) a current fill level of the at least one exhaust gas component in the exhaust gas catalyst (130) based on the first signal and a theoretical catalyst model of the exhaust gas catalyst (130),
• sense (230) a signal of the second exhaust gas sensor (147) as a second signal indicative of the at least one exhaust gas component,
• determine (240) a first deviation of the second signal from a target signal corresponding to an expected signal based on the determined current fill level,
• reinitiate (260) the theoretical catalyst model when the first deviation of the second signal from the target signal exceeds a predetermined threshold value such that a corrected current fill level of the at least one exhaust gas component after the reinitiating (260) reduces the first deviation of the second signal from the target signal,
• adjust (270) an air-fuel mixture supplied to the internal-combustion engine (120) based on the corrected current fill level so as to adjust a fill level of the at least one exhaust gas component in the exhaust gas catalyst (130) to a target fill level,
• determine (280) a second deviation between the first and the second signals after the reinitiating (260) of the theoretical catalyst model and after the adjusting (270) of the fill level to the target fill level,
• set (290) a momentary target value of the second signal as a first target value, and
• adjust (290) the air-fuel mixture such that the second signal is indicative of a lambda value of one by changing the first target value to a second target value.

A non-transitory computer-readable storage medium containing operating instructions for an internal-combustion engine (120) with an exhaust gas aftertreatment system including an exhaust gas catalyst (130), at least a first exhaust gas sensor (145) arranged upstream of the exhaust gas catalyst (130), and at least a second exhaust gas sensor (147) arranged downstream of the exhaust gas catalyst (130), the operating instructions, when executed via a computer, are configured to:

• sense (210) at least one signal of the first exhaust gas sensor (145) as a first signal indicative of at least one exhaust gas component,
• determine (220) a current fill level of the at least one exhaust gas component in the exhaust gas catalyst (130) based on the first signal and a theoretical catalyst model of the exhaust gas catalyst (130),
• sense (230) a signal of the second exhaust gas sensor (147) as a second signal indicative of the at least one exhaust gas component,
• determine (240) a first deviation of the second signal from a target signal corresponding to an expected signal based on the determined current fill level,
• reinitiate (260) the theoretical catalyst model when the first deviation of the second signal from the target signal exceeds a predetermined threshold value such that a corrected current fill level of the at least one exhaust gas component after the reinitiating (260) reduces the first deviation of the second signal from the target signal,
• adjust (270) an air-fuel mixture supplied to the internal-combustion engine (120) based on the corrected current fill level so as to adjust a fill level of the at least one exhaust gas component in the exhaust gas catalyst (130) to a target fill level,
• determine (280) a second deviation between the first and the second signals after the reinitiating (260) of the theoretical catalyst model and after the adjusting (270) of the fill level to the target fill level,
• set (290) a momentary target value of the second signal as a first target value, and
• adjust (290) the air-fuel mixture such that the second signal is indicative of a lambda value of one by changing the first target value to a second target value.