Patent ID: 7483782

Claim:
A method of estimating fuel and air ratio in each cylinder of an internal combustion engine including a gas exhaust circuit, cylinders connected to a manifold, a turbine for providing a pressurized air and fuel mixture to the cylinders and a detector measuring a fuel and air ratio downstream from the manifold, comprising: providing a physical model representing in real time expulsion of gases from each cylinder and travel in the exhaust circuit up to the detector, the physical model including a physical model of expulsion of gases from each cylinder, a physical model of the manifold, a physical model of flow rate of gases passing through the turbine, and a physical model of lag time due to transportation of gases from each cylinder to the detector; defining an estimation of the fuel and air ratio measured by the detector from at least one variable of the physical model representing in real time the expulsion of the gases; coupling the physical model representing in real time the expulsion of the gases with an adaptive type nonlinear estimator wherein the estimation of the measured fuel/air ratio measurement is utilized; and performing a real time estimation of the fuel and air ratio value in each cylinder from the adaptive type nonlinear estimator.