Abstract
ZLEV (the Zero Level Emission Vehicle) 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); 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); high precision air-fuel ratio feed back control (catalyst condition predictive control, and others).