Strategies to Meet US 1994/95 Diesel Engine Federal Emission Legislation for HSDI diesel Engine Powered Vehicles

The forthcoming US passenger car and light-duty truck emission limits are currently the most stringent ones worldwide. The paper discusses which type of diesel engine has the best chance of fulfilling those requirements and what development strategy has to be followed. A comparative analysis between IDI and DI diesel engines shows the potential of the HSDI diesel engine to meet NOx/particulates limits of 0.4/0.08 g/min while maintaining its fuel economy advantage. Appropriate technological strategies are outlined. Besides the well-known technologies such as central position of injector and piston bowl, multi-valve cylinder head, inlet port swirl control etc., main emphasis is placed on the optimization of mixture preparation using fuel systems with variable injection rates as well as oxidation and DENOX catalysts.