Abstract: A reductant injection control strategy for controlling an amount of nitrogen oxide reducing agent injected upstream of a selective reduction catalyst uses an ammonia sensor located downstream of the catalyst. An open loop injection quantity is first determined based on operation conditions. Ammonia concentration detected downstream of the catalyst is controlled to a desired value, with the desired value based on catalyst temperature and the open loop injection quantity.

Abstract: A carbon monoxide sensor placed downstream of the catalytic converter and a temperature sensor placed upstream of the converter in a diesel engine provide information to build a real time CO conversion efficiency versus catalyst temperature curve to determine whether a catalyst has deteriorated beyond a predetermined point with respect to On-Board Diagnostic (OBD) requirements. Pre catalyst CO concentration is inferred from the engine operating conditions, and catalyst temperature is determined using the temperature sensor output and the engine exhaust flow heat transfer model. The real time curve is compared to a reference curve to determine catalyst performance. Catalyst performance with respect to CO conversions can then be correlated to that for HC and NOx to meet OBD requirements.

Abstract: A method of monitoring catalyst activity that includes injecting hydrocarbon into the engine exhaust flow sufficient to maintain a constant concentration of reductant into the catalyst under variable engine exhaust flow conditions thereby permitting an accurate calculation of the actual HC conversion by the catalyst, and a determination of whether the catalyst is currently meeting emission regulations.

Abstract: A system and method of controlling J/L specific energy deposition in accordance with either measured or estimated values of engine or vehicle operational parameters in order to optimize emission reduction versus energy cost over a driving cycle. A typical strategy varies the J/L specific energy deposition in relation to a measured or estimated value of a relevant parameter such as engine-out NOx concentration to improve energy cost versus emission performance over a driving cycle.

Abstract: A reductant injection control strategy for controlling an amount of nitrogen oxide reducing agent injected upstream of a selective reduction catalyst uses a NOx sensor located downstream of the catalyst. An open loop injection quantity is first determined based on operation conditions. Nitrogen oxide conversion efficiency of the catalyst is controlled by controlling the reductant injection based on after catalyst NOx sensor reading and engine out nitrogen oxide concentration.

Abstract: A reductant injection control strategy for controlling an amount of nitrogen oxide reducing agent injected upstream of a selective reduction catalyst uses an ammonia sensor located downstream of the catalyst. An open loop injection quantity is first determined based on operation conditions. Ammonia concentration detected downstream of the catalyst is controlled to a desired value, with the desired value based on catalyst temperature and the open loop injection quantity.

Abstract: A reductant injection control strategy for controlling an amount of nitrogen oxide reducing agent injected upstream of a selective reduction catalyst uses an ammonia sensor located downstream of the catalyst. An open loop injection quantity is first determined based on operation conditions. Ammonia concentration detected downstream of the catalyst is controlled to a desired value, with the desired value based on catalyst temperature and the open loop injection quantity.