Modeling mass flow via bypass line to combustion engine exhaust gas turbocharger involves multiplying pressure before actuator element, pressure and temperature factors, reduced cross-sectional area

The method involves determining mass flow by the reduced cross-sectional area determined an actuator element position by deriving a first factor from the quotient of the pressure before and after the actuator element, a second factor from the temperature before the actuator element, computing a reduced passage area from the actuator element position forming the product of the pressure before the actuator element, the factors and the reduced area. The method involves determining the mass flow (10) by the reduced cross-sectional area determined by the position of an actuator element by deriving a first factor from the quotient (18) of the pressure before and after the actuator element, deriving a second factor from the temperature (30) before the actuator element, computing the reduced passage area (28) from the actuator element position (24) and deriving the mass flow from the product of the pressure before the actuator element, the factors and the reduced area. Die Erfindung betrifft ein Modell für ein Wastegate. In dem Vorwärtsmodell wird aus der Position der Wastegate-Klappe, der Temperatur vor der Turbine und dem Druckverhältnis vor und nach der Turbine der Massenstrom durch das Wastegate bestimmt. Im Rückwärtsmodell wird aus den Sollwerten für den Druck vor und nach der Turbine, der Temperatur vor der Turbine und einem Sollwert für den Massenstrom durch das Wastegate ein Sollwert für die Wastegate-Position berechnet.