A method for controlling an air-fuel ratio based on an oxygen storage amount of a catalyst may include: performing, by a controller, a catalyst oxygen storage amount (OSA) feedback control for a rich control of the air-fuel ratio so that the oxygen storage amount of the catalyst is within a threshold value; and performing, by the controller, a target voltage feedback control for a lean or rich control of the air-fuel ratio so that an output voltage value of an oxygen sensor provided in the rear of the catalyst satisfies a target voltage value.

A decrease in purification performance of a system as a whole is suppressed in cases where catalysts are arranged in an upstream side portion and in a downstream side portion of an exhaust passage in an internal combustion engine. A first catalyst, a sensor and a second catalyst are sequentially arranged in the exhaust passage of the internal combustion engine, wherein a switch is made between lean control and rich control in such a manner that an amount of increase or decrease in a storage amount of oxygen falls within a predetermined range, and in cases where the rich control is carried out after performing a predetermined number of times of rich control, the rich control is continued until an air fuel ratio detected by the sensor becomes equal to or less than a rich determination threshold value which is smaller than a stoichiometric air fuel ratio.

A method is presented for regulating a filling of an exhaust gas component reservoir of a catalytic converter in the exhaust of an internal combustion engine. Using a first catalytic converter model, an actual fill level of the exhaust gas component reservoir is ascertained. An aging state of the catalytic converter is determined; and a set of model parameters of the first catalytic converter model is allocated to the aging state; the individual model parameters being ascertained by interpolation from basic values of model parameters, the basic values having been determined for at least two different aging states of a catalytic converter of identical design.

A method for controlling a filling level of an exhaust gas component accumulator of a catalytic converter in the exhaust gas of an internal combustion engine where an actual filling level of the accumulator is determined with a first catalytic converter model. The method includes forming a lambda setpoint is formed, wherein a predetermined target fill level is converted into a base lambda setpoint via a second system model reverse of the first catalytic converter model, a deviation of the actual fill level from the predetermined target fill level is determined and processed to a lambda setpoint correction value via a fill level control unit, a sum of the base lambda setpoint value and the lambda setpoint value correction value is formed, and said sum is used to form a correction value, with which fuel metering to at least one combustion chamber of the internal combustion engine is influenced.

A method of purifying exhaust gas discharged from an engine using a three-way catalyst may include: calculating, by a controller, an oxygen mass flow rate flowing into the three-way catalyst based on an air-fuel ratio and an exhaust gas flow rate measured by a front oxygen sensor arranged at a front end of the three-way catalyst; calculating, by the controller, an oxygen storage capacity (OSC) and an oxygen storage amount (OSA) of the three-way catalyst by integrating the oxygen mass flow rate; correcting, by the controller, the calculated oxygen storage amount based on an actual voltage measurement value of the exhaust gas measured by a rear oxygen sensor arranged at a rear end of the three-way catalyst; and controlling, by the controller, a control variable related to performance of the three-way catalyst based on the corrected oxygen storage amount and the oxygen storage capacity.

The controller includes a fuel amount control unit adjusting amount of fuel supplied to a cylinder through feedback control with an air-fuel ratio deviation as input, a target air-fuel ratio adjustment unit alternately repeating a lean period process and a rich period process, and a learning value correction unit updating a learning value to compensate for a steady deviation in an air-fuel ratio. If an absolute value of an oxygen amount deviation is less than a determination value, the learning value update unit updates a learning value only when one of the lean period process and the rich period process is switched to the other one. If the absolute value of the oxygen amount deviation is greater than or equal to the determination value, the learning value is updated both when one of the processes is switched to the other one and when the switching is reversed.

A method for operating an engine system including an internal combustion engine and an exhaust gas aftertreatment device, including: carrying out a fill level control to control a fill level of the exhaust gas aftertreatment device as a function of a predefined fill level setpoint value; operating a pilot control for the fill level control; and adapting the pilot control as a function of a deviation between a measured lambda value and a modeled lambda value.

The exhaust purification system of an internal combustion engine has: exhaust purification catalysts 20, 24 arranged in an exhaust passage and able to store oxygen; and a control device 31 for calculating an EGR rate of intake gas supplied to combustion chambers 5 and for controlling an air-fuel ratio of the exhaust gas flowing into the catalysts. The control device alternately switches the air-fuel ratio between a rich air-fuel ratio and a lean air-fuel ratio, and controls the air-fuel ratio so that the air-fuel ratio is switched from the lean air-fuel ratio to the rich air-fuel ratio when the oxygen storage amount of the catalyst is greater, when the calculated EGR rate is relatively high, compared to when it is relatively low.

A method and device including an interface, a memory, and a processor for the control of a fill level of a catalytic converter for an internal combustion engine of a motor vehicle. A setpoint variable is ascertained as a function of an expected operating variable for the fill level, and the expected operating variable is determined as a function of information from at least one further sensor, which acquires information about an operating state of the motor vehicle.

A method and a control device for regulating a modeled fill level of an exhaust gas component reservoir of a catalytic converter of an internal combustion engine. Regulation of the modeled fill level is accomplished using a system model. An actual maximum storage capacity of the catalytic converter for the exhaust gas component is ascertained during operation of the internal combustion engine and is taken into consideration in regulating the modeled fill level.