Abstract: A powertrain includes an internal combustion engine having a combustion chamber and an aftertreatment system. A method for reducing NOx emissions in the powertrain includes monitoring an actual exhaust gas feedstream ratio of NO2 to NO, monitoring a desired exhaust gas feedstream ratio of NO2 to NO, comparing the actual and the desired exhaust gas feedstream ratios of NO2 to NO, and selectively initiating a NO2 generation cycle based upon the comparison of the actual and the desired exhaust gas feedstream ratios of NO2 to NO comprising injecting fuel mass into the combustion chamber after a primary combustion event.

Abstract: A method for monitoring a hydrocarbon-selective catalytic reactor device of an exhaust aftertreatment system of an internal combustion engine operating lean of stoichiometry includes injecting a reductant into an exhaust gas feedstream upstream of the hydrocarbon-selective catalytic reactor device at a predetermined mass flowrate of the reductant, and determining a space velocity associated with a predetermined forward portion of the hydrocarbon-selective catalytic reactor device. When the space velocity exceeds a predetermined threshold space velocity, a temperature differential across the predetermined forward portion of the hydrocarbon-selective catalytic reactor device is determined, and a threshold temperature as a function of the space velocity and the mass flowrate of the reductant is determined.

Abstract: Exhaust emissions from a spark-ignition direct-injection engine connected to an oxidation catalytic device and a selective catalyst reduction device having a capacity to store ammonia reductant are controlled. The engine operates in a first combustion mode to generate ammonia reductant, stored on the second aftertreatment device. The engine operates lean of stoichiometry and nitrides of oxygen in the exhaust gas feedstream are reduced on the second aftertreatment device.

Abstract: A method for supplying reductant into an exhaust gas feedstream for an internal combustion engine includes storing a fuel/reductant blend in the fuel storage and delivery system, separating the reductant from the fuel/reductant blend, storing the reductant in a reductant storage tank, and injecting the reductant into the exhaust gas feedstream upstream of the aftertreatment device.

Abstract: A method for initiating a regeneration mode in selective catalytic reduction device utilizing hydrocarbons as a reductant includes monitoring a temperature within the aftertreatment system, monitoring a fuel dosing rate to the selective catalytic reduction device, monitoring an initial conversion efficiency, selecting a determined equation to estimate changes in a conversion efficiency of the selective catalytic reduction device based upon the monitored temperature and the monitored fuel dosing rate, estimating changes in the conversion efficiency based upon the determined equation and the initial conversion efficiency, and initiating a regeneration mode for the selective catalytic reduction device based upon the estimated changes in conversion efficiency.

Abstract: Where oxygenated hydrocarbons, such as ethanol, may be considered for use as a reductant to be added to diesel or gasoline engine exhaust for promoting the catalyzed reduction of NOx to N2, there is a need to continually adjust the amount of the reductant to be added as engine and catalyst operating conditions change. It is found that useful methods, to be practiced using a suitably programmed on-vehicle computer, can be based on a correlation for ethanol, or other specific reductant, with continually measured values of catalyst temperature, the oxygen and NOx contents of the exhaust, and the volumetric flow rate of the exhaust over a reduction catalyst, such as silver supported on alumina, selected for reduction of NOx to nitrogen. Effective amounts of the reductant for substantial reduction of NOx may be reliably determined using at least such parameters.

Abstract: A powertrain includes an internal combustion engine having a combustion chamber and an aftertreatment system. A method for reducing NOx emissions in the powertrain includes monitoring an actual exhaust gas feedstream ratio of NO2 to NO, monitoring a desired exhaust gas feedstream ratio of NO2 to NO, comparing the actual and the desired exhaust gas feedstream ratios of NO2 to NO, and selectively initiating a NO2 generation cycle based upon the comparison of the actual and the desired exhaust gas feedstream ratios of NO2 to NO comprising injecting fuel mass into the combustion chamber after a primary combustion event.

Abstract: A method for controlling hydrocarbon delivery to a hydrocarbon selective catalytic reduction device configured to receive an exhaust gas flow from an internal combustion engine includes monitoring measurable variable terms including factors affecting a conversion efficiency in the hydrocarbon selective catalytic reduction device, determining classifications of the measurable variable terms based upon measurable variable ranges, determining a desired hydrocarbon delivery value range based upon the classifications; and utilizing the desired hydrocarbon delivery value range to control the hydrocarbon delivery to the hydrocarbon selective catalytic reduction device.

Abstract: A method for controlling a powertrain includes selectively initiating an ammonia generation cycle, including injecting fuel into a combustion chamber of an engine before a primary combustion event to a calibrated air fuel ratio in a range lean of stoichiometry based upon generation of NOx within the combustion chamber, injecting fuel into the combustion chamber after the primary combustion event based upon an overall air fuel ratio in a range rich of stoichiometry and resulting generation of molecular hydrogen, and utilizing a catalyst device between the engine and a selective catalytic reduction device to produce ammonia.

Abstract: A method for supplying reductant into an exhaust gas feedstream for an internal combustion engine includes storing a fuel/reductant blend in the fuel storage and delivery system, separating the reductant from the fuel/reductant blend, storing the reductant in a reductant storage tank, and injecting the reductant into the exhaust gas feedstream upstream of the aftertreatment device.

Abstract: A method for monitoring a hydrocarbon-selective catalytic reactor device of an exhaust aftertreatment system of an internal combustion engine operating lean of stoichiometry includes injecting a reductant into an exhaust gas feedstream upstream of the hydrocarbon-selective catalytic reactor device at a predetermined mass flowrate of the reductant, and determining a space velocity associated with a predetermined forward portion of the hydrocarbon-selective catalytic reactor device. When the space velocity exceeds a predetermined threshold space velocity, a temperature differential across the predetermined forward portion of the hydrocarbon-selective catalytic reactor device is determined, and a threshold temperature as a function of the space velocity and the mass flowrate of the reductant is determined.

Abstract: A method and apparatus are provided for generating a reductant in an exhaust gas feedstream of a compression-ignition internal combustion engine upstream of a hydrocarbon-selective catalytic reduction catalyst. The method comprises injecting a quantity of fuel into the exhaust gas subsequent to a combustion event whereat a temperature of the exhaust gas is in a range of 670 K to 1100 K at a start of the injection. The generated reductant comprises an active species including an oxygenated fuel species.

Abstract: A method for initiating a regeneration mode in selective catalytic reduction device utilizing hydrocarbons as a reductant includes monitoring a temperature within the aftertreatment system, monitoring a fuel dosing rate to the selective catalytic reduction device, monitoring an initial conversion efficiency, selecting a determined equation to estimate changes in a conversion efficiency of the selective catalytic reduction device based upon the monitored temperature and the monitored fuel dosing rate, estimating changes in the conversion efficiency based upon the determined equation and the initial conversion efficiency, and initiating a regeneration mode for the selective catalytic reduction device based upon the estimated changes in conversion efficiency.

Abstract: A method for controlling hydrocarbon delivery to a hydrocarbon selective catalytic reduction device configured to receive an exhaust gas flow from an internal combustion engine includes monitoring measurable variable terms including factors affecting a conversion efficiency in the hydrocarbon selective catalytic reduction device, determining classifications of the measurable variable terms based upon measurable variable ranges, determining a desired hydrocarbon delivery value range based upon the classifications; and utilizing the desired hydrocarbon delivery value range to control the hydrocarbon delivery to the hydrocarbon selective catalytic reduction device.

Abstract: An exhaust aftertreatment system connected to an internal combustion engine operative lean of stoichiometry includes first and second selective catalytic reactor devices. A preferred ratio of hydrocarbon:NOx to achieve a preferred concentration of ammonia immediately downstream of the first selective catalytic reactor device is determined. An ethanol-based reductant is dispensed upstream of the first selective catalytic reactor device.

Abstract: A method for controlling a powertrain includes selectively initiating an ammonia generation cycle, including injecting fuel into a combustion chamber of an engine before a primary combustion event to a calibrated air fuel ratio in a range lean of stoichiometry based upon generation of NOx within the combustion chamber, injecting fuel into the combustion chamber after the primary combustion event based upon an overall air fuel ratio in a range rich of stoichiometry and resulting generation of molecular hydrogen, and utilizing a catalyst device between the engine and a selective catalytic reduction device to produce ammonia.

Abstract: Exhaust emissions from a spark-ignition direct-injection engine connected to an oxidation catalytic device and a selective catalyst reduction device having a capacity to store ammonia reductant are controlled. The engine operates in a first combustion mode to generate ammonia reductant, stored on the second aftertreatment device. The engine operates lean of stoichiometry and nitrides of oxygen in the exhaust gas feedstream are reduced on the second aftertreatment device.

Abstract: A method for controlling timing of ignition of a fuel charge in a compression-ignition engine operating in a controlled auto-ignition mode wherein the engine includes controllable intake and exhaust valve actuation systems is described. The method comprises determining a preferred ignition timing for a cylinder charge and a mass of the fuel charge based upon operator torque request. A portion of the fuel charge is partially oxidized during a negative valve overlap period immediately prior to a compression stroke. Magnitude of the portion of the fuel charge is based upon the preferred ignition timing of the cylinder charge. A remainder of the fuel charge is injected into the cylinder during the compression stroke.

Abstract: There is provided a method and apparatus for exhaust gas purifying, especially NOx reduction. The apparatus comprises an internal combustion engine adapted to operate primarily lean of stoichiometry. There is an aftertreatment system that is fluidly connected to and adapted to treat exhaust gas flowing from the internal combustion engine. The aftertreatment system comprises a hydrocarbon-selective catalytic reduction device. There is an injector device adapted to inject a blend of fuel and an ignition improver into the exhaust gas at a location upstream of the hydrocarbon-selective catalytic reduction device. A control module is adapted to control the injector device to inject the blended fuel and cetane-enhancer into the exhaust gas when temperature of the exhaust gas at the location of the injection is greater than about 280° C.

Abstract: The disclosure sets forth operating a spark-ignition, direct-fuel injection internal combustion engine equipped with an exhaust aftertreatment system including a lean-NOx adsorber device. The engine is operated substantially un-throttled and at a lean air/fuel ratio and a first fuel pulse is injected to meet an engine output torque during a compression stroke of each engine cycle prior to a spark-ignition event. When regeneration of the lean-NOx adsorber device is commanded, a second fuel pulse is injected during a second engine stroke of each engine cycle.