During the last few decades diesel engine development has primarily been driven by subjects such as fuel economy, performance and durability. However, in the meantime questions concerning their environmental compatibility have gained greater importance and are today strongly influencing diesel engine development trends. Actual efforts concentrate on a further reduction of NOx and particulate emissions as well as engine noise. Nevertheless, it is still important to maintain the favorable fuel economy which is typical for DI-diesel engines and ensures low CO2-emissions. One of the keys to reach the above mentioned goals is the further optimization of the combustion process by means such as improvement of the injection system, optimization of the combustion chamber design, 4-valve low swirl concepts with variable swirl and injection rate shaping, all in combination with the improvement of the transient behavior by advanced engine control systems. This paper summarizes the potential of the above mentioned topics, based on results of ECE 13-Mode and US Transient Test. Additional means such as exhaust gas recirculation, water injection, advanced turbocharging, reduced oil consumption and low sulfur fuel in combination with oxidation catalysts are also discussed. (A)
Abstract