Technology for Reducing Exhaust Gas Emissions in Zero Level Emission Vehicles(ZLEV) 1999-01-0772

ZLEV was accomplished by applying the Three-Stage Emission Management System, utilizing ultra-precise combustion and exhaust gas conversion control technology, and dividing the operation into three-stages of just after engine start, the warm-up stage, and normal running. These individual component technologies include improving engine combustion (high swirl combustion by variable valve timing and lift) and performing fuel control optimization during engine startup to reduce unburned HC emission, quick catalyst activation (engine control and catalyst improvements), HC adsorption of a hybrid catalyst (catalyst improvement and desorption conversion control), and high precision air-fuel ratio feed back control (catalyst condition predictive control, and others).