Investigations of Emission Control Systems for Gasoline Direct Injection Engines with a Focus on Removal of Particulate Emissions

The removal of particulate emissions from gasoline injection engines is a new challenge within the exhaust aftertreatment system that will arise with the introduction of limits for particle number emitted by gasoline engines. Besides a possible adjustment of the engine management to lower the particulate emissions, catalyzed gasoline particulate filters (GPF) are conceivable as efficient pollution control devices. As an advantage, these catalyzed filters in addition could be able to support the conversion of all other regulated pollutants. Therefore, an emission study was carried out with systems consisting of a three-way catalyst and a catalyzed GPF and the impact of a dedicated washcoat on the filtration efficiency of the filter was analyzed. The conversion performance of the gasoline particulate filters was examined with regard to carbon monoxide, hydrocarbons and nitrous oxides emissions. Furthermore, the influence of the additional converter on fuel consumption and CO₂ emissions over different driving cycles will be discussed. In a detailed exhaust system study a correlation between the distance of engine-outlet to GPF-inlet and the filtration efficiency of the system was observed.