A Study on Cold Emission Reduction of Direct-Injection Gasoline Engine

Abstract

Reducing cold emissions (EM) in internal combustion engines is an important issue to alleviate an environmental impact. In this study, we developed a technology to reduce cold EM by controlling the in-cylinder state using a variable valve system in a direct injection gasoline engine. As a result, we promoted fuel evaporation in cold conditions and reduced unburned hydrocarbons (Total Hydrocarbon: THC) and particulate number emissions (Particle Number: PN) significantly. Specifically, this was achieved by effectively utilizing the energy of the intake air through Late Intake Valve Opening (LIVO). Additionally, we elucidated the reduction mechanism using high-speed gas measurements and visualization techniques.