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The subject of this paper is to discuss the use of advanced combustion controls of direct injection diesel engines, to achieve simultaneous improvements in thermal efficiency while maintaining minimum pollutant emissions. In recent years, the emissions produced in the transportation sector are becoming increasingly scrutinized, leading to significantly strengthened emissions legislations with regard to NOx and CO2, especially under Real Driving Emission (RDE) conditions. Therefore, diesel combustion improvements are key to overcoming these challenges. This paper reports the following two innovative Diesel combustion control technologies to realize the objectives mentioned above. 1 Combustion improvement by accurate Combustion Rate Shaping (CRS), CRS enables direct control of in-cylinder pressure trace and heat release rate.

Future diesel engine legislation Tier 4 / Stage V and EU6d demand further improvements to reduce CO2 while keeping the already low NOx emissions levels. For US trucks a more strict limit of 0.2 g/bhp-hr NOx emissions need to be achieved. In this trade-off, system costs and complexity of the after-treatment are defining the constraint in which the common rail fuel injection system layout has to be defined. The increase of rail pressure was in the past the major step to control the soot emissions in view of low engine-out NOx emissions by applying massive EGR. With the on-going development of NOx-aftertreatment by Selective Catalytic Reduction (SCR), conversion efficiencies of up to 97% allow to reduce the EGR usage and rail pressure usage. In that context, the steepness of injection rate, the nozzle flow rate and the injection pressure are remaining parameters to control the NOx emissions.