Patent ID: 8224592

Claim:
Method for estimating the intake air flow rate in an internal combustion engine to determine and control fuel flow rate to the engine, the engine being provided with an air intake system, said system comprising intake conduit and valve means for controlling the air flow rate flow to the intake conduit, wherein the method comprises the phases of: implementing a first algorithm based on a “Saint-Venant model” and a second algorithm based on the “Filling and Emptying model” to determine respectively a first (MAF_SV) and a second (MAF_FE) intake mass air flow rate in said intake conduit; selecting said first (MAF_SV) mass air flow rate in case the ratio (β) between the pressures (P up , P down ) at the inlet and at the outlet of said valve means is lower than a previously defined threshold value (β tsh ) having a value between 0.9 and 0.95; selecting said second (MAF_FE) mass air flow rate in case said ratio (β) between said pressures (P up , P down ) at the inlet and at the outlet of said valve means is higher than said previously defined threshold value (β tsh ), wherein the selected first and second mass air flow rates are used to determine and control a proper fuel flow rate to the engine, wherein the mass air flow rate is determined by being mapped as a function of engine speed and valve means opening angle, and wherein determination of the air flow rate is based on an air pressure drop across the valve means, and controlling and supplying fuel to the engine at a proper fuel flow rate by using the selected first and second mass air flow rates.