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Four-way, integrated, diesel emission control systems that combine selective catalytic reduction for NOx control with a continuously regenerating trap to remove diesel particulate matter were evaluated under real-world, on-road conditions. Tests were conducted using a semi-tractor with an emissions year 2000, 6-cylinder, 12 L, Volvo engine rated at 287 kW at 1800 rpm and 1964 N-m. The emission control system was certified for retrofit application on-highway trucks, model years 1994 through 2002, with 4-stroke, 186-373 kW (250-500 hp) heavy-duty diesel engines without exhaust gas recirculation. The evaluations were unique because the mobile laboratory platform enabled evaluation under real-world exhaust plume dilution conditions as opposed to laboratory dilution conditions. Real-time plume measurements for NOx, particle number concentration and size distribution were made and emission control performance was evaluated on-road.

Vibration signals from diesel engines were analyzed for the purpose of isolating signals relating to injection or combustion which could be used to time the engines. Nonintrusive sensors, magnetically attached to the engine, were used to obtain these vibration signals. Components believed to be associated with combustion or fuel injection were electronically isolated from the remaining engine noise, and subsequently processed to produce specific timing signals. Digital data acquisition and averaging methods were used, coupled with computerized frequency analysis. The signals were experimentally correlated with the combustion process over a wide range of injection timing. The electronic processing system developed provides a real time digital measure of the timing. Data on the accuracy and correlation of experimental measurements will be presented.

The performance of a closed-loop electronic fuel injection timing control system for diesel engines has been investigated, both experimentally and analytically. The Electronic Control System (ECS) studied is a version of the “Optimizer,” a peak seeking control which can find the maximum of one variable with respect to another. In this case, it was used to find the timing for maximum brake torque (MBT). The ECS can also be operated in a “biased” mode in which it will hold the timing either advanced or retarded of MBT, but in a fixed relationship to it. Performance and emissions of a medium duty engine equipped with the ECS were measured on an engine dynamometer. The results clearly demonstrate that, for a variety of operating conditions and for two fuels, the ECS can find and hold the timing at MBT or in fixed relationship to it.

An adaptive control system which determines the optimum system parameters based on the engine response to changes in those parameters, has been tested as an ignition timing control system on several gaseous fueled engines. The changes in the MBT timing for speed, load, air-fuel ratio, and fuel type were explored. The ability of the control system to correct the timing for these parameters was demonstrated. An air-fuel ratio control based on the same technique is also discussed.