A method for controlling exhaust gas aftertreatment in an exhaust gas aftertreatment system having at least one nitrogen oxide storage catalyst and at least one catalyst for selective catalytic reduction is provided, wherein, in phases of a high load, a combustion engine is operated with a substoichiometric fuel/air mixture, and nitrogen oxides in the exhaust gas are reduced in the nitrogen oxide storage catalyst to ammonia, which is stored in the catalyst for selective catalytic reduction, and, when the storage capacity of the catalyst for selective catalytic reduction is exceeded, the combustion engine is operated with a superstoichiometric fuel/air mixture, thus allowing nitrogen oxides in the catalyst for selective catalytic reduction to be reduced by the stored ammonia.

An emissions control system for treating exhaust gas containing NO.sub.x emissions from an internal combustion engine comprises a selective catalytic reduction (SCR) device that stores reductant that reacts with the NO.sub.x emissions, a reductant supply system configured to inject the reductant according to a reductant storage model; NO.sub.x module(s) configured to generate an NO.sub.x concentration signal indicating an NO.sub.x concentration, temperature module(s) configured to generate a temperature signal indicating an SCR temperature of the SCR device, and a control module operably connected to the reductant supply system, the NO.sub.x module, and the temperature module. The control module is configured to determine an amount of the reductant that is parasitically oxidized based on the NO.sub.x concentration signal and the temperature signal, and to determine a correction factor based on the amount of parasitically oxidized reductant to modify the reductant storage model.

An ammonia combustion engine, a mobile or stationary system having an ammonia combustion engine, and a method comprise operating an ammonia combustion engine with a combustion chamber and an injection device which is in fluidic connection with the combustion chamber. The ammonia can be metered into the combustion chamber. Ammonia is metered into the combustion chamber such that an exhaust gas stream generated by the ammonia combustion engine has a predetermined molar ratio of ammonia to nitrogen oxides independently of the current operating point of the ammonia combustion engine.

A method for acquiring a corrected nitrogen oxide and/or corrected ammonia value in an internal combustion engine by determining that the engine is in an overrun cut-off phase, interrupting an injection of urea, acquiring a nitrogen oxide reference value from a nitrogen oxide reference signal generated by a nitrogen oxide sensor and acquiring an ammonia reference value from an ammonia reference signal generated by an ammonia sensor, and acquiring a corrected nitrogen oxide value from a nitrogen oxide signal generated by the nitrogen oxide sensor during normal operation of the engine, taking into account the nitrogen oxide reference value, and acquiring a corrected ammonia value from an ammonia signal generated by the ammonia sensor during normal operation of the engine, taking into account the ammonia reference value.

An amount of ammonia flowing out from an SCR catalyst is reduced at the time of carrying out rich spike control to reduce an amount of NOx stored in an NSR catalyst. The NSR catalyst and the SCR catalyst are arranged in order in an exhaust passage of an internal combustion engine which is able to be operated at a lean air fuel ratio, wherein a target air fuel ratio of exhaust gas flowing into the NSR catalyst during the rich spike control is made higher within the range of a rich air fuel ratio, in the case where the outflow of ammonia from the SCR catalyst in accompany with the rich spike control is estimated or detected, than in the case where it is not estimated or detected.

The abnormality diagnosis system 1, 1, 1 of an ammonia detection device 46, 71 comprises: an air-fuel ratio detection device 41, 72 arranged in the exhaust passage 22 at the downstream side of the catalyst 20; an air-fuel ratio control part 51 configured to control an air-fuel ratio of exhaust gas; and an abnormality judgment part 52 configured to judge abnormality of the ammonia detection device. The air-fuel ratio control part performs rich control making the air-fuel ratio of the inflowing exhaust gas richer than a stoichiometric air-fuel ratio. The abnormality judgment part judges that the ammonia detection device is abnormal if, after start of the rich control, an output value of the ammonia detection device does not rise to a reference value before the air-fuel ratio detected by the air-fuel ratio detection device falls to a rich judged air-fuel ratio richer than a stoichiometric air-fuel ratio.

The exhaust purification system of an internal combustion engine comprises: a catalyst arranged in an exhaust passage of the internal combustion engine and able to store oxygen; an ammonia detection device arranged in the exhaust passage at a downstream side of the catalyst in a direction of flow of exhaust; and an air-fuel ratio control part configured to control an air-fuel ratio of inflowing exhaust gas flowing into the catalyst to a target air-fuel ratio. The air-fuel ratio control part is configured to perform rich control making the target air-fuel ratio richer than a stoichiometric air-fuel ratio, and make the target air-fuel ratio leaner than the stoichiometric air-fuel ratio when an output value of the ammonia detection device rises to a reference value in the rich control.

The exhaust purification system of an internal combustion engine 100, 100, 100 comprises: a catalyst 20 arranged in an exhaust passage 22 and able to store oxygen; an ammonia detection device 46, 71 and an air-fuel ratio detection device 41, 72 arranged in the exhaust passage at a downstream side of the catalyst; and an air-fuel ratio control part configured to control an air-fuel ratio of exhaust gas flowing into the catalyst to a target air-fuel ratio. The air-fuel ratio control part performs rich control making the target air-fuel ratio richer than a stoichiometric air-fuel ratio, in the rich control, reduces a rich degree of the target air-fuel ratio when an output value of the ammonia detection device rises to a reference value, and ends the rich control when an air-fuel ratio detected by the air-fuel ratio detection device falls to a rich judged air-fuel ratio.

An engine controller performs air-fuel ratio sub-feedback control in which a target air-fuel ratio is switched from a rich air-fuel ratio to a lean air-fuel ratio when a rear air-fuel ratio detected by an air-fuel ratio sensor becomes less than or equal to a rich determination value, and the target air-fuel ratio is switched from the lean air-fuel ratio to the rich air-fuel ratio when the rear air-fuel ratio becomes greater than or equal to a lean determination value. To perform the sub-feedback control, the controller variably sets the lean determination value to a value indicating a leaner air-fuel ratio when an amount of overshoot of the rear air-fuel ratio to a richer value than a stoichiometric air-fuel ratio after switching the target air-fuel ratio from the rich air-fuel ratio to the lean air-fuel ratio is relatively large than when the amount of overshoot is relatively small.

Systems and apparatuses include an apparatus including an aftertreatment system control circuit structured to receive a signal indicative of an exhaust gas characteristic from a sensor, determine an aftertreatment system characteristic based on the exhaust gas characteristic, determine an acceptable input value responsive to the aftertreatment system characteristic, and control at least one of a fuel system actuator and an air handling actuator to achieve or substantially achieve the acceptable input value.