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Due to increasing interest in air quality concerns, worldwide legislation towards lower particle emissions is getting more and more stringent. Because of this, the development towards even cleaner internal combustion engines (ICE) with Spark Ignition (SI) is of upmost importance. Along with the development targeting higher efficiency and specific power output, Direct Injection (DI) technology became more and more important than Port Fuel Injection (PFI) and is one of the main SI engine development fields. SI engine mixture preparation (PFI or DI) and combustion produce much lower particle raw emissions than Diesel engines, but these emissions also have to be reduced to fulfill worldwide legislation and customer expectations. In this paper the focus lies on the analysis and development methods used to drastically reduce particle emissions in a gasoline-fueled DI SI engine.

Investigations were performed, in which the emission behavior of renewable and conventional fuels of different composition and renewable fuel components was observed. The influence of the start of injection on the emissions at WOT was investigated. This shows how much wall and valve wetting as well as the available evaporation time affects the mixture formation of the different fuels. Further, the air fuel ratio in an operating point for catalytic converter heating, with medium engine temperatures, was varied. This shows the ability of evaporation of the fuels at engine warm-up conditions and sub-stochiometric λ-values. The studied fuels were four fuel mixtures of significantly different composition of which three were compliant with the European fuel standard EN 228. A RON 98 in-field fuel, a Euro 6 reference fuel, an Anti-Spark-Fouling (ASF) fuel (designed for minimum soot production) and a potentially completely renewable, thus CO2-neural, fuel, which is designed by Dr. Ing. h.c.