Abstract: In a method for determining a mass airflow in an air duct using a mass airflow sensor, sensor signals at successive times, indicating the magnitude of the mass airflow, are captured and, using a characteristic curve for the mass airflow sensor, corresponding values are determined for the mass airflow. In doing so, a time series of signals is subjected to a vibration analysis, which determines a fundamental vibration and at least one prescribed harmonic vibration of the fundamental vibration, and the existence of a backflow is established if the ratio of the strength of the harmonic vibration to the strength of the fundamental vibration exceeds a prescribed threshold value.

Abstract: The invention relates to a device with an air inlet manifold (1) and an air mass sensor arrangement (2) inserted radially therein, the insertion opening (3) of which is arranged perpendicular to the airflow direction (6) in the manifold (1). A wing-shaped shielding body (7) is arranged before the insertion opening (3) such as to cover the insertion opening (3) and guarantee a streamline airflow to the insertion opening (3) and the essentially straight surface thereof, transverse to the flow direction of the air flowing over said surface, is oriented perpendicular to the insertion direction of the air mass sensor arrangement (2).

Abstract: In a method for determining a mass airflow in an air duct using a mass airflow sensor, sensor signals at successive times, indicating the magnitude of the mass airflow, are captured and, using a characteristic curve for the mass airflow sensor, corresponding values are determined for the mass airflow. In doing so, a time series of signals is subjected to a vibration analysis, which determines a fundamental vibration and at least one prescribed harmonic vibration of the fundamental vibration, and the existence of a backflow is established if the ratio of the strength of the harmonic vibration to the strength of the fundamental vibration exceeds a prescribed threshold value.