Effect of Exhaust Valve Timing on Gasoline Engine Performance and Hydrocarbon Emissions

摘要: Despite remarkable progress made over the past 30 years, automobiles continue to be a major source of hydrocarbon emissions. The objective this study is evaluate whether variable exhaust valve opening (EVO) and closing (EVC) can used reduce An automotive gasoline engine was tested with different EVO EVC timings under steady-state start-up conditions. first strategy that evaluated uses early standard EVC. Although gas temperature increased catalyst light-off time reduced, rapid drop in cylinder increases cylinder-out hydrocarbons such degree net increase emissions results. second Early reduces by increasing keeps hydrocarbon-rich from piston crevice leaving cylinder. result are reduced 27%.