| abstract |
A physically-based, generalizable method to estimate the in-cylinder oxygen fraction from production viable measurements or estimates of exhaust oxygen fraction, fresh air flow, charge flow, fuel flow, turbine flow and EGR flow. The oxygen fraction estimates can be sensitive to errors in the EGR and turbine flow, and in other embodiments, a high-gain observer is implemented to improve the estimate of EGR flow. The observer is applicable to engines utilizing high pressure cooled exhaust gas recirculation, variable geometry turbocharging and flexible intake valve actuation as well as other engines. |