METHOD OF MEASURING AIR MASS FLOW

摘要

PURPOSE: A method of measuring air mass flow is provided to secure a corresponding air mass flow sensor capable of reliably detecting a backflow of inflow gas generated due to pulsation. CONSTITUTION: In a method of measuring air mass flow, the air mass flow in an air pipe(2) is decided via an air mass flow sensor(4). The method of measuring air mass flow obtains signals corresponding to air mass flow values by the air mass flow sensor and sensor signals are obtained. In the method of measuring air mass flow, values about the air mass flow from the sensor signals via a characteristic curve are decided. Vibration analysis of the time sequence of signals including several signals obtained previously is performed. The vibration analysis measures fundamental vibration and more than one harmonic vibration of the fundamental vibration and compares parameters of the fundamental vibration and the set harmonic vibration. A backflow for the average air flow due to the pulsation is generated, when the ratio of the parameter of the harmonic vibration to the parameter of the fundamental vibration exceeds a set reference value.