Abstract: An on-board reductant delivery assembly 407 for an exhaust line of an internal combustion engine powered motor vehicle is provided. In a preferred embodiment the system includes a nozzle 410 for atomizing delivery of reductant into the exhaust line. A transfer tube 418 is connected with the nozzle 410 for delivering the reductant. A housing 422 having an outlet is connected with the transfer tube 418 opposite the nozzle 410. The housing 422 has a front end forming a mixing chamber 496 and a main body with inlets 426, 456 for pressurized air and reductant. An electrically powered fluid metering pump 476 having exposed coils 508 is cooled by air which is delivered to said housing 422 through the pressurized air inlet 456. The fluid metering device 476 has an inlet connected with the housing reductant inlet.

Abstract: A method is disclosed for controlling the delivery of compressed air and a reductant for oxides of nitrogen to a mixer from which the air/reductant mixture flows through a nozzle and into an exhaust gas created by a combustion engine. A control signal provided to an air compressor is varied as the exhaust gas pressure changes to maintain a predetermined differential pressure across the nozzle. The desired flow rate of reductant into the exhaust gas is calculated based upon the engine speed, engine load, catalyst temperature, and gas space velocity flowing through the catalyst. A reductant control signal, based upon the calculated reductant flow rate, is provided to a metering pump that delivers the reductant into the mixer. Calculations of the reductant control signal take into account the air pressure that the reductant pump sees inside the mixer.

Abstract: A system and method for controlling reductant injection upstream of a selective reduction catalyst (SCR) to overcome NOX inhibiting effects by injecting reductant in an amount proportional to engine out NOX concentration when the NOX concentration is above a predetermined level and injecting predetermined amounts of reductant into the SCR catalyst when engine out NOX concentration is below the predetermined level such as when the engine is idling or decelerating.

Abstract: An on-board diagnostic method for detecting whether a diesel emissions control system is functioning properly by continuously monitoring the temperature rise generated by the catalyst and the light-off temperature with reference to theoretical values stored in an engine control computer. When either of the parameters falls below a predetermined threshold value, the vehicle emissions may exceed emission standards and, if so, the system causes a malfunction indicator light (MIL) to be energize to advise the driver of the need for service.