Carbon canister air fuel ratio estimation on high performance engine

The increasingly stringent vehicle emission constraints press on the car manufacturers to decrease in hydrocarbons quantities from evaporative emission system. Activated carbon canister has been used for 30 years to capture the gasoline vapors from fuel evaporative system whose most of vehicles are equipped. The newer amendments on Low-Emission Vehicle programs, known as LEV-II, recently adopted by CARB (California Air Resources Board), impose on the vehicles to be Zero Emission Vehicles (ZEV or battery electric vehicles) and that the carbon canister has to be purged frequently: this can cause poor quality idle condition and exhaust emission levels increase as well. The article describes an input high gain observer algorithm to estimate the canister air/fuel mixture in order to improve both idle speed engine roughness and fuel evaporative emissions. Furthermore system identification of Air-to-Fuel Ratio (AFR) has been used for observer performance simulations.