Exhaust Purification Performance Enhancement by Early Activation of Three Way Catalysts for Gasoline Engines Used in Hybrid Electric Vehicles
Three-way catalyst (TWC) converters are used to purify the toxic substances such as carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons (HC) emitted from gasoline engines. However, a large amount of emissions could be emitted before the TWC reaching its light-off temperature during cold start. For hybrid electric vehicles (HEVs) powered by gasoline engines, the emission purification performance by TWC unfortunately become worse caused by mode switching from engine to battery and vice versa, which is possible to generate cold start conditions over and over for TWC In this study, targeting at reducing the emissions from series HEVs by early activation of TWC, numerical simulations with experiments are carried out. A HEV is tested on a chassis dynamometer under Worldwide Light-duty Test Cycle (WLTC) mode; the upstream and downstream gas conditions of the close-coupled catalyst converter are measured.