An engine system includes an internal combustion engine having an engine block with one or more piston-cylinder arrangements communicating with an intake manifold and an exhaust manifold, a charge air passageway to the intake manifold, and an exhaust gas passageway that receives exhaust gas from the exhaust manifold. The engine system also includes one or more turbochargers each including a compressor to compress charge air and output the compressed charge air to the charge air passageway and a turbine that receives exhaust gas from the exhaust gas passageway and drives the compressor in response to the exhaust gas passing through the turbine. An air pump is positioned downstream of the compressor that supplies a portion of the compressed charge air into the exhaust gas passageway upstream of the turbine, such that the turbine receives both exhaust gas and compressed charge air.

An abnormality determination apparatus for an ammonia sensor is usable in an exhaust purification system including a catalyst, a supply apparatus, an ammonia sensor, an NO.sub.X sensor, and an oxygen sensor. During a continuation period within which ammonia supply to the catalyst continues after the supply apparatus stops supply of reductant, the abnormality determination apparatus calculates the ammonia concentration on a downstream side of the catalyst as a first concentration value, based on an output of the ammonia sensor and an output of the oxygen sensor. During the continuation period, the abnormality determination apparatus calculates the ammonia concentration on the downstream side of the catalyst as a second concentration value, based on an output of the NO.sub.X sensor and the output of the oxygen sensor. The abnormality determination apparatus determines presence or absence of abnormality in the ammonia sensor based on the first concentration value and the second concentration value.

A method includes determining that at least one diesel emissions fluid (DEF) doser of an exhaust aftertreatment system is likely frozen based on at least one of an ambient air temperature or a DEF source temperature; operating an engine in a cylinder cutout mode in response to the determination that the at least one DEF doser is likely frozen; and, discontinuing the cylinder cutout mode in response to determining that the at least one DEF doser is in a predefined condition.

The present disclosure describes methods for evaluating quality of DEF dosed to an EAS including a close coupled SCR unit a downstream SCR unit. A NOx conversion efficiency of the close coupled SCR unit and a NOx conversion efficiency of the downstream SCR unit are used to evaluate quality of DEF. In some embodiments, the NOx conversion efficiency of close coupled SCR unit is used to evaluate quality of DEF. Operation of an EAS using the results of the evaluation of quality of DEF are described.

Methods and system are provided to heat a catalyst of an after-treatment system for a vehicle. The after-treatment system comprises a heating module having a plurality of heating elements. Each of the plurality of heating elements is independently operable to provide thermal energy to the catalyst of the after-treatment system. One or more of the heating elements of the heating module are selectively operated to provide heat to the catalyst based on an operational parameter of the after-treatment system.

An exhaust aftertreatment system and associated method for purifying an exhaust gas feedstream of a lean-burn or other compression-ignition internal combustion engine is described. An instruction set is executable to determine an engine-out NO2 concentration upstream of an oxidation catalyst and determine a first parameter associated with O2 concentration. A consumption of oxygen in the oxidation catalyst due to oxidation reactions is determined, and a concentration of NO2 generated by the oxidation catalyst is determined based upon the consumption of oxygen in the oxidation catalyst. A concentration of NO2 downstream of the oxidation catalyst is determined. A NO2/NOx ratio in the exhaust gas feedstream downstream of the oxidation catalyst is determined based upon the concentration of NO2 downstream of the oxidation catalyst and the NOx concentration measured by the downstream NOx sensor. The oxidation catalyst is evaluated based upon the NO2/NOx ratio.

The subject matter of the present invention relates to trained machine-learning models (300), methods (200, 400) and apparatuses (500) allowing a future resonant frequency of a catalyst for selective reduction of nitrogen oxides (SCR) to be predicted, the resonant frequency being representative of a concentration of a reducing agent within the SCR. The SCR forms part of a system for after-treatment of a flow of exhaust gases of an internal combustion engine with which a motor vehicle is provided. The general principle of the invention is based on the observation of correlations between the resonant frequency of an SCR and the concentration of ammonia present within the SCR. This observation led the inventor to envision using machine learning to create a trained machine-learning model in order to predict the resonant frequency of an SCR. In the invention, the trained machine-learning model is a so-called predictive model in which significant correlations are discovered in a set of past observations and in which it is sought to generalize these correlations to cases that have not yet been observed.

A system includes an exhaust aftertreatment system in exhaust gas receiving communication with an engine including a plurality of cylinders where the engine is structured to operate according to low load conditions and where a controller is structured to determine that at least one diesel emissions fluid (DEF) doser is frozen based on at least one of an ambient air temperature and a DEF source temperature. The controller is structured to operate the engine according to a skip-fire mode in response to a DEF flag indicating that the at least one DEF doser is frozen. The skip-fire mode comprises firing a portion of the plurality of cylinders that is less than a total amount of cylinders of the plurality of cylinders. The controller is structured to discontinue the skip-fire mode in response to determining that the at least one DEF doser is likely thawed.

In a control apparatus, a heater adjuster performs a regeneration task of causing a heater to heat a sensing member of a particulate matter sensor to burn particulate matter deposited on the sensing member to thereby remove the particulate matter from the sensing member. The heater adjuster performs a deposition reduction task of maintaining, for a predetermined duration, a temperature of the sensing member at a deposition reduction temperature that reduces additional particulate-matter deposition on the sensing member. The predetermined duration is defined from completion of a regeneration task to a time when an environmental condition around the particulate matter sensor is determined to be stable. The heater adjuster stops the heater from heating the sensing member if a condition determiner determines that the environmental condition around the particulate matter sensor is stable.

One or more techniques and/or systems are disclosed for providing localized heating within an engine exhaust aftertreatment system. The localized heating includes DEF injector nozzle heating with a DEF dispensing system having a DEF fluid supply and a DEF injector fluidly coupled to the DEF fluid supply. The DEF injector includes a DEF injector nozzle. The DEF dispensing system further includes a DEF heater positioned in proximity to the DEF injector nozzle. The DEF heater is configured to locally heat an area surrounding the DEF injector nozzle.