PROCEDE ET DISPOSITIF DE MISE EN OEUVRE D'UNE UNITE DE DOSAGE D'UN CATALYSEUR

Operating a metering device for supplying a reactant to a catalyst associated with a combustion unit, in which a mass flow rate of the reactant is injected into the exhaust gas as a function of at least one catalyst operating parameter and/or at least one combustion unit operating parameter, comprises determining the mass flow rate from an alpha value (not defined) and/or a value for a mass flow rate of nitrogen oxides. An Independent claim is also included for apparatus for operating a metering device for supplying a reactant to a catalyst associated with a combustion unit, comprising a control unit for controlling a mass flow rate of the reactant injected into an exhaust gas and one or more sensors for capturing at least one heat engine operating parameter (sic) and at least one combustion unit operating parameter, where the control unit's memory contains a field of alpha characteristics and/or a field of nitrogen oxide mass flow rate characteristics to determine the mass flow rate of the reactant as a function of an alpha value or the value of a mass flow rate of nitrogen oxides.