Abstract: A dosing control system for an exhaust system of an engine includes: a tank containing a reductant solution having urea; an injector operable to inject the reductant solution into an exhaust flow upstream of an SCR apparatus; first and second NOx sensors disposed to sense NOx emissions in the exhaust flow upstream and downstream, respectively, of the SCR apparatus; and a control module. The control module is disposed in signal communication with the first and second NOx sensors and in operable communication with the injector, the control module being operable to set an original dosing level and decrease a dosing of the reductant solution injected by the injector based on a determination from signals received from the first and second NOx sensors that a reduction in a conversion efficiency of the SCR apparatus below a defined level of conversion efficiency has occurred.

Abstract: An exhaust treatment system includes an SCRF device, a reductant delivery system, and an SCR storage module. The SCRF device includes a filter portion having a washcoat formed thereon that defines a washcoat thickness (WCT). The reductant delivery system is configured to inject a reductant that reacts with the washcoat based on a reductant storage model. The SCR storage module is in electrical communication with the reductant delivery system to provide the reductant storage model the amount of reductant to be injected based on the reductant storage model. The exhaust treatment system further includes a WCT compensation module configured to electrically communicate a WCT compensation value to the SCR storage module. The SCR storage module modifies the reductant storage model according to the WCT compensation value such that the amount of ammonia that slips from the SCRF device is reduced thereby increasing a storage efficiency of the SCRF device.

Abstract: An exhaust treatment system configured to treat exhaust gas generated by an internal combustion engine includes a reductant delivery system that injects a reductant solution into an exhaust gas. A selective catalyst reduction (SCR) device reacts with the reductant solution to reduce NOx from the exhaust gas. A control module is in electrical communication with the SCR device and the reductant delivery system. The control module determines at least one of an injection status of the reduction delivery system and a performance of the SCR device. The control module further determines at least one debounce time for delaying diagnosis of a NOx sensor based on at least one of the injection status and the performance of the SCR device.

Abstract: An engine assembly includes an exhaust system having a first SCR catalyst, a second SCR catalyst in fluid communication with the first SCR catalyst, and an injector configured to inject reductant into the exhaust system. A controller is configured to estimate a first amount of ammonia stored in the first SCR catalyst and to estimate a second amount of ammonia stored in the second SCR catalyst. The controller is operatively connected to the injector and configured to control the amount of reductant injected by the injector. The controller controls the injector based on the first amount, the second amount, and a temperature of a substrate disposed in the second SCR catalyst.

Abstract: An exhaust treatment system configured to treat exhaust gas generated by an internal combustion engine includes a reductant delivery system that injects a reductant solution into an exhaust gas. A selective catalyst reduction (SCR) device reacts with the reductant solution to reduce NOx from the exhaust gas. A control module is in electrical communication with the SCR device and the reductant delivery system. The control module determines at least one of an injection status of the reduction delivery system and a performance of the SCR device. The control module further determines at least one debounce time for delaying diagnosis of a NOx sensor based on at least one of the injection status and the performance of the SCR device.

Abstract: An exhaust gas treatment system including a reductant delivery system configured to introduce reductant solution to an exhaust gas flowing through the exhaust gas treatment system. An amount of the reductant solution injected is based on an initial control parameter. A selective catalyst reduction device is configured to chemically react with the reductant solution to induce a NOx conversion that reduces a level of NOx in the exhaust gas. A reductant quality sensor is configured to generate an electrical signal indicating a quality of the reductant solution. The exhaust gas treatment system further includes a reductant quantity control module configured to generate a pre-control parameter that modifies the initial control parameter based on the quality of the reductant solution.

Abstract: A system and method is provided for enhancing the performance of an SCR device, particularly by routinely reducing the amount of reductant deposits accumulated in an exhaust gas system, when the reductant is injected at a reduced temperature. The system may include an engine, an exhaust gas system, an SCR device, an injection device, and a controller configured to execute the present method. The controller may be configured to select an initial injection rate and an initial injection temperature for the reductant; estimate the amount of accumulated reductant deposits present within the exhaust gas system; compare the amount of accumulated reductant deposits to a threshold amount of reductant deposits allowable in the exhaust gas system; and initiate a reductant deposit burn-off mode when the amount of accumulated reductant deposits is greater than the threshold amount of reductant deposits allowable in the exhaust gas system.

Abstract: An exhaust treatment system includes a selective catalyst reduction filter (SCRF) device, a reductant delivery system, and a reductant storage module. The SCRF device includes a filter portion having a washcoat disposed thereon that defines a washcoat thickness (WCT). The reductant delivery system is configured to inject a reductant that reacts with the washcoat. The reductant storage module is in electrical communication with the reductant delivery system to determine a reductant setpoint that controls the amount of reductant injected from the reductant delivery system. The exhaust treatment system further includes a WCT compensation module configured to electrically communicate a WCT compensation value to the reductant storage module. The reductant storage module adjusts the setpoint according to the WCT compensation value such that the amount of ammonia that slips from the SCRF device is reduced as compared to the first setpoint.

Abstract: An engine assembly includes an exhaust system having a first SCR catalyst, a second SCR catalyst in fluid communication with the first SCR catalyst, and an injector configured to inject reductant into the exhaust system. A controller is configured to estimate a first amount of ammonia stored in the first SCR catalyst and to estimate a second amount of ammonia stored in the second SCR catalyst. The controller is operatively connected to the injector and configured to control the amount of reductant injected by the injector. The controller controls the injector based on the first amount, the second amount, and a temperature of a substrate disposed in the second SCR catalyst.

Abstract: System and methods can identify a source of nitrogen oxide reduction inefficiency in an exhaust system including first and second selective catalytic reduction (SCR) catalysts connected in series along an exhaust line. The methods and systems can determine which of the first and second SCR catalysts is a source of nitrogen oxide reduction inefficiency based on the temperatures of the exhausts gases flowing through the first and second SCR catalysts.

Abstract: An exhaust gas treatment system includes a SCR device that stores a reductant that reacts with the NOx emissions and a reductant supply system to inject the reductant according to a reductant load model. At least one temperature sensor or model generates a temperature signal indicating an SCR temperature of the SCR device. The exhaust gas treatment system further includes a control module in electrical communication with the reductant supply system. The control module is configured to determine an amount of reductant that slips from the SCR device based on the at least one temperature signal and the rate of change of the SCR temperature. The control module further determines a correction factor based on the amount of slipped reductant to modify the reductant load model.

Abstract: An exhaust gas treatment system includes a reductant delivery system configured to introduce a reductant solution to an exhaust gas flowing through the exhaust gas treatment system. A selective catalyst reduction device is configured to chemically react with the reductant solution to induce a NOx conversion that reduces a level of NOx in the exhaust gas. A reductant quality sensor is configured to generate an electrical signal indicating a quality of the reductant solution. The exhaust gas treatment system further includes a rationality diagnostic control module configured to rationalize the reductant quality sensor based on a comparison between the quality of the reductant solution and the NOx conversion.

Abstract: A selective catalytic reduction (SCR) device monitoring system includes an engine out NOx monitoring module, an SCR out NOx monitoring module configured and disposed to monitor NOx released from the SCR device, and a NOx storage model module operatively connected to the engine out NOx module and the SCR out NOx monitoring module. The NOx storage model module is configured and disposed to determine an amount of NOx stored in the SCR device. A consumed ammonia correction model module is operatively coupled to the NOx storage model module and configured and disposed to calculate a corrected consumed ammonia correction factor.

Abstract: An exhaust treatment system includes an SCRF device, a reductant delivery system, and an SCR storage module. The SCRF device includes a filter portion having a washcoat formed thereon that defines a washcoat thickness (WCT). The reductant delivery system is configured to inject a reductant that reacts with the washcoat based on a reductant storage model. The SCR storage module is in electrical communication with the reductant delivery system to provide the reductant storage model the amount of reductant to be injected based on the reductant storage model. The exhaust treatment system further includes a WCT compensation module configured to electrically communicate a WCT compensation value to the SCR storage module. The SCR storage module modifies the reductant storage model according to the WCT compensation value such that the amount of ammonia that slips from the SCRF device is reduced thereby increasing a storage efficiency of the SCRF device.

Abstract: An exhaust treatment system includes a selective catalyst reduction filter (SCRF) device, a reductant delivery system, and a reductant storage module. The SCRF device includes a filter portion having a washcoat disposed thereon that defines a washcoat thickness (WCT). The reductant delivery system is configured to inject a reductant that reacts with the washcoat. The reductant storage module is in electrical communication with the reductant delivery system to determine a reductant setpoint that controls the amount of reductant injected from the reductant delivery system. The exhaust treatment system further includes a WCT compensation module configured to electrically communicate a WCT compensation value to the reductant storage module. The reductant storage module adjusts the setpoint according to the WCT compensation value such that the amount of ammonia that slips from the SCRF device is reduced as compared to the first setpoint.

Abstract: A system and method is provided for enhancing the performance of an SCR device, particularly by routinely reducing the amount of reductant deposits accumulated in an exhaust gas system, when the reductant is injected at a reduced temperature. The system may include an engine, an exhaust gas system, an SCR device, an injection device, and a controller configured to execute the present method. The controller may be configured to select an initial injection rate and an initial injection temperature for the reductant; estimate the amount of accumulated reductant deposits present within the exhaust gas system; compare the amount of accumulated reductant deposits to a threshold amount of reductant deposits allowable in the exhaust gas system; and initiate a reductant deposit burn-off mode when the amount of accumulated reductant deposits is greater than the threshold amount of reductant deposits allowable in the exhaust gas system.

Abstract: System and methods can identify a source of nitrogen oxide reduction inefficiency in an exhaust system including first and second selective catalytic reduction (SCR) catalysts connected in series along an exhaust line. The methods and systems can determine which of the first and second SCR catalysts is a source of nitrogen oxide reduction inefficiency based on the temperatures of the exhausts gases flowing through the first and second SCR catalysts.

Abstract: An exhaust gas treatment system includes a SCR device that stores a reductant that reacts with the NOx emissions and a reductant supply system to inject the reductant according to a reductant load model. At least one temperature sensor or model generates a temperature signal indicating an SCR temperature of the SCR device. The exhaust gas treatment system further includes a control module in electrical communication with the reductant supply system. The control module is configured to determine an amount of reductant that slips from the SCR device based on the at least one temperature signal and the rate of change of the SCR temperature. The control module further determines a correction factor based on the amount of slipped reductant to modify the reductant load model.

Abstract: A dosing control system for an exhaust system of an engine includes: a tank containing a reductant solution having urea; an injector operable to inject the reductant solution into an exhaust flow upstream of an SCR apparatus; first and second NOx sensors disposed to sense NOx emissions in the exhaust flow upstream and downstream, respectively, of the SCR apparatus; and a control module. The control module is disposed in signal communication with the first and second NOx sensors and in operable communication with the injector, the control module being operable to set an original dosing level and decrease a dosing of the reductant solution injected by the injector based on a determination from signals received from the first and second NOx sensors that a reduction in a conversion efficiency of the SCR apparatus below a defined level of conversion efficiency has occurred.

Abstract: A selective catalytic reduction (SCR) device monitoring system includes an engine out NOx monitoring module, an SCR out NOx monitoring module configured and disposed to monitor NOx released from the SCR device, and a NOx storage model module operatively connected to the engine out NOx module and the SCR out NOx monitoring module. The NOx storage model module is configured and disposed to determine an amount of NOx stored in the SCR device. A consumed ammonia correction model module is operatively coupled to the NOx storage model module and configured and disposed to calculate a corrected consumed ammonia prediction factor.