Potential of a Low Pressure Drop Filter Concept for Direct Injection Gasoline Engines to Reduce Particulate Number Emission

The automotive industry is currently evaluating the gasoline particulate filter (GPF) as a potential technology to reduce particulate emissions from gasoline direct injection (GDI) engines. In this paper, several GPF design measures which were taken to obtain a filter with lower pressure drop when compared to our previous concept will be presented. Based on engine test bench and vehicle test results, it was determined some soot will accumulate on the GPF walls, resulting in an increase in pressure drop. However, the accumulated soot will be combusted under high temperature and high O₂ concentration conditions. In a typical vehicle application, passive regeneration will likely occur and a cycle of soot accumulation and combustion might be repeated in the actual driving conditions. Since the amount of soot trapped by the GPF on a GDI engine is significantly lower than a diesel particulate filter (DPF) on a diesel engine, a thin wall and low cell density filter concept is applicable for providing lower pressure drop without PM. The unique GDI-engine application characteristics allow for a new cell structure to be developed and applied to the GPF.