METHOD FOR DETECTING THE IMPURITY OF BIODIESEL FUEL BASED ON THE ASSESSMENT OF THE RELATIVE RATIO OF AIR AND FUEL

摘要

1. A method for detecting an impurity of biodiesel fuel in an internal combustion engine, comprising at least the following stages, in which:! making a first estimate of the air to fuel ratio (RAFR) using at least a first sensor, the output of which reflects the actual RAFR value; ! a second estimate of the air to fuel ratio (RAFR) is made using an engine electronic control unit (ECU), the estimation is performed by measuring the stoichiometric air to fuel ratio (A / F) ST for oil diesel fuel, mass air flow rate (MAF) and the amount of injected fuel (Qfuel); and! determine the discrepancy between the values obtained as a result of the first and second assessments. ! 2. The method of claim 1, further comprising using a pre-calculated set of value relationships between the variance and the percentage of biodiesel relative to fuel oil to determine the amount of biodiesel impurity. ! 3. The method of claim 1, wherein the first sensor used for the first estimate is a lambda probe. ! 4. The method of claim 1, wherein the second RAFR estimate is performed by the formula:! ! where MAF is the mass air flow, Qfuel is the amount of fuel, and (A / F) ST is the stoichiometric ratio of air to fuel for oil diesel. ! 5. The method according to claim 4, wherein to determine the amount of biodiesel impurity, a correspondence is established between the actual stoichiometric ratio of air and fuel for a mixture of biodiesel