Abstract: Various embodiments of an apparatus, system, and method are disclosed for reducing NOx emissions on an SCR catalyst. For example, according to one representative embodiment, an apparatus for reducing NOx emissions in an engine exhaust includes a NOx reduction target module that is configured to determine a NOx reduction requirement that includes an amount of NOx in the exhaust gas stream to be reduced on a selective catalytic reduction (SCR) catalyst. The apparatus also includes an ammonia target module that is configured to determine an ammonia addition requirement that includes an amount of ammonia added to the exhaust gas stream to achieve the NOx reduction requirement. The apparatus also includes a reductant target module that is configured to determine a reductant injection requirement that includes an amount of reductant added to the exhaust gas stream to achieve the ammonia addition requirement.

Abstract: One embodiment is a method including operating an SCR system at a plurality of commanded ammonia to NOx input ratios, providing a plurality of data indicating NOx output from the SCR system for the plurality of commanded ammonia to NOx input ratios, and evaluating the plurality of data to diagnose the SCR system. Additional embodiment are methods, systems, and apparatuses including SCR diagnostics. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

Abstract: According to one exemplary embodiment, an apparatus is disclosed for estimating an NOx conversion efficiency of an SCR catalyst. The apparatus includes a catalyst degradation module for determining an SCR catalyst degradation factor and a NOx concentration module for determining an SCR catalyst inlet NOx concentration based on an interpretation of at least one NOx detector signal. Additionally, the apparatus includes an NH3 concentration module for determining an SCR catalyst inlet NH3 concentration, a temperature module for determining an SCR catalyst bed temperature of the at least one SCR catalyst, and a space velocity (SV) module for determining an exhaust gas SV for the SCR catalyst. A NOx conversion efficiency module calculates a NOx conversion efficiency value based at least partially on the SCR catalyst degradation factor, the SCR catalyst inlet NOx concentration, the SCR catalyst inlet NH3 concentration, the exhaust gas SV, and the SCR catalyst bed temperature.

Abstract: A system, method, and software for triggering regeneration of an adsorber connected with a flow of exhaust from an engine. An exhaust sulfur flow rate module estimates a sulfur accumulation rate associated with an adsorber as a function of a flow of fuel. A sulfur removal rate module estimates a sulfur removal rate associated with the adsorber. An accumulated sulfur loading module includes a counter the value of which is increased as a function of the sulfur accumulation rate and decreased as a function of the sulfur removal rate. A combustion manager module controls an engine to regenerate the adsorber once the counter reaches an upper threshold value.

Abstract: According to one representative embodiment, an apparatus for reducing NOx emissions in an engine exhaust gas stream of an engine system having a selective catalytic reduction (SCR) system with an SCR catalyst positioned downstream of a reductant injector includes a NOx reduction target module and a reductant module. The NOx reduction target module is configured to determine a NOx reduction requirement, which includes an amount of NOx in the exhaust gas stream to be reduced on the SCR catalyst. The reductant module is configured to determine the amount of reductant added to the exhaust gas stream to achieve the NOx reduction requirement. The amount of reductant added to the exhaust gas stream is a function of at least one ammonia storage characteristic of the SCR catalyst, at least one reductant-to-ammonia conversion characteristic, and a conversion capability of an AMOX catalyst in exhaust receiving communication with the SCR catalyst.

Abstract: Various embodiments of an apparatus, system, and method are disclosed for controlling NOx conversion in a selective catalytic reduction (SCR) system. According to one representative embodiment, an apparatus includes a duty cycle factor module and a NOx conversion mode selection module. The duty cycle factor module is configured to determine a duty cycle factor of an internal combustion engine where the duty cycle factor represents predicted driving conditions of a vehicle in which the internal combustion engine is housed. The NOx conversion mode selection module is configured to command NOx conversion in the SCR system according to a first NOx conversion mode if the duty cycle factor is within a duty cycle factor range and according to a second NOx conversion mode if the duty cycle factor is not within the duty cycle factor range.

Abstract: A system, method, and software that rapidly heats a diesel oxidation catalyst unit to an effective operating temperature at engine startup is disclosed. Upon ignition of an engine an electronic control unit is operable to lower a fresh air flow target value to a reduced fresh air flow target value as well as lower a valve opening limit of an exhaust gas recirculation valve to a reduced valve opening limit. The electronic control unit monitors a temperature value of a flow of exhaust entering the diesel oxidation catalyst unit until the temperature value reaches a first predetermined threshold value. After reaching the first predetermined threshold value, the electronic control unit causes the fuel system to set post-injection fueling to a predetermined post-injection fueling value until the temperature value of the flow of exhaust entering the diesel oxidation catalyst unit reaches a second predetermined threshold value.

Abstract: A system, method, and software for controlling regeneration and desulfurization of a NOx adsorber is disclosed. An electronic control unit is connected with an engine for selectively controlling operation of the engine between a rich operating mode and a lean operating mode. A NOx adsorber is in fluid communication with a flow of exhaust from the engine. A NOx adsorber manager module is executable by the electronic control unit to determine the need to operate in a de-NOx mode or a de-SOx mode. If the NOx adsorber manager module determines a need exists to operate in the de-NOx mode and the de-SOx mode at the same time, the NOx adsorber manager module executes the de-SOx mode.

Abstract: Various embodiments of an apparatus, system, and method are disclosed for reducing NOx emissions on an SCR catalyst. For example, according to one representative embodiment, an apparatus for reducing NOx emissions in an engine exhaust includes a NOx reduction target module that is configured to determine a NOx reduction requirement that includes an amount of NOx in the exhaust gas stream to be reduced on a selective catalytic reduction (SCR) catalyst. The apparatus also includes an ammonia target module that is configured to determine an ammonia addition requirement that includes an amount of ammonia added to the exhaust gas stream to achieve the NOx reduction requirement. The apparatus also includes a reductant target module that is configured to determine a reductant injection requirement that includes an amount of reductant added to the exhaust gas stream to achieve the ammonia addition requirement.

Abstract: Various embodiments of an apparatus, system, and method are disclosed for reducing NOx emissions using ammonia storage on an SCR catalyst. For example, according to one representative embodiment, an apparatus for reducing NOx emissions in an engine exhaust includes a NOx reduction target module that is configured to determine a NOx reduction requirement. The apparatus also includes an ammonia storage module that is configured to determine an ammonia storage modifier. An ammonia target module of the apparatus is configured to determine an ammonia addition requirement. The ammonia target module is communicable in data receiving communication with the ammonia storage module to receive the ammonia storage modifier, which is added to the ammonia addition requirement. The apparatus also includes a reductant target module that is configured to determine a reductant injection requirement that includes an amount of reductant added to the exhaust gas stream to achieve the ammonia addition requirement.

Abstract: Various embodiments of an apparatus, system, and method are disclosed for reducing NOx emissions on an SCR catalyst. For example, according to one representative embodiment, an apparatus for reducing NOx emissions in an engine exhaust includes a NOx reduction target module that is configured to determine a NOx reduction requirement that includes an amount of NOx in the exhaust gas stream to be reduced on a selective catalytic reduction (SCR) catalyst. The apparatus also includes an ammonia target module that is configured to determine an ammonia addition requirement that includes an amount of ammonia added to the exhaust gas stream to achieve the NOx reduction requirement. The apparatus also includes a reductant target module that is configured to determine a reductant injection requirement that includes an amount of reductant added to the exhaust gas stream to achieve the ammonia addition requirement.

Abstract: According to one representative embodiment, an apparatus for determining the degradation of a selective catalytic reduction (SCR) catalyst of an engine exhaust aftertreatment system includes a system properties module configured to store at least one system dynamics property value of the exhaust system at a first time and receive the at least one system dynamics property value of the exhaust aftertreatment system at a second time subsequent to the first time. The apparatus also includes a system dynamics module configured to determine a storage capacity of the SCR catalyst based on a comparison between the at least one system dynamic property value at the first time and the at least one system dynamic property value at the second time. Additionally, the apparatus includes an SCR catalyst degradation factor module configured to determine an SCR catalyst degradation factor based at least partially on the storage capacity of the SCR catalyst.

Abstract: A system, method, and software for regenerating an adsorber connected with a flow of exhaust from an engine. An open-loop control module for ramping up and maintaining a temperature value of an adsorber to a regeneration temperature value by controlling an air fuel ratio value of an engine to operate at an open-loop controlled variable duty cycle. A closed-loop control module is operable to take control from the open-loop control module to maintain the adsorber at the regeneration temperature value if the temperature value of the adsorber deviates from the regeneration temperature value by controlling the air fuel ratio value of the engine to operate at a closed-loop controlled variable duty cycle.

Abstract: A system, method, and software for triggering regeneration of an adsorber connected with a flow of exhaust from an engine. An exhaust sulfur flow rate module estimates a sulfur accumulation rate associated with an adsorber as a function of a flow of fuel. A sulfur removal rate module estimates a sulfur removal rate associated with the adsorber. An accumulated sulfur loading module includes a counter the value of which is increased as a function of the sulfur accumulation rate and decreased as a function of the sulfur removal rate. A combustion manager module controls an engine to regenerate the adsorber once the counter reaches an upper threshold value.

Abstract: A system, method, and software that rapidly heats a diesel oxidation catalyst unit to an effective operating temperature at engine startup is disclosed. Upon ignition of an engine an electronic control unit is operable to lower a fresh air flow target value to a reduced fresh air flow target value as well as lower a valve opening limit of an exhaust gas recirculation valve to a reduced valve opening limit. The electronic control unit monitors a temperature value of a flow of exhaust entering the diesel oxidation catalyst unit until the temperature value reaches a first predetermined threshold value. After reaching the first predetermined threshold value, the electronic control unit causes the fuel system to set post-injection fueling to a predetermined post-injection fueling value until the temperature value of the flow of exhaust entering the diesel oxidation catalyst unit reaches a second predetermined threshold value.

Abstract: A system, method, and software for regenerating an adsorber connected with a flow of exhaust from an engine. An open-loop control module for ramping up and maintaining a temperature value of an adsorber to a regeneration temperature value by controlling an air fuel ratio value of an engine to operate at an open-loop controlled variable duty cycle. A closed-loop control module is operable to take control from the open-loop control module to maintain the adsorber at the regeneration temperature value if the temperature value of the adsorber deviates from the regeneration temperature value by controlling the air fuel ratio value of the engine to operate at a closed-loop controlled variable duty cycle.

Abstract: A system, method, and software for controlling regeneration and desulfurization of a NOx adsorber is disclosed. An electronic control unit is connected with an engine for selectively controlling operation of the engine between a rich operating mode and a lean operating mode. A NOx adsorber is in fluid communication with a flow of exhaust from the engine. A NOx adsorber manager module is executable by the electronic control unit to determine the need to operate in a de-NOx mode or a de-SOx mode. If the NOx adsorber manager module determines a need exists to operate in the de-NOx mode and the de-SOx mode at the same time, the NOx adsorber manager module executes the de-SOx mode.