IC engine air intake mass flow rate measurement - using first order low-pass filter with variable filter factor dependent on rate of change of measured value and operating parameter of engine

摘要

A mass flowrate sensor is incorporated in the engine air intake pipe. The measured valve provided by the sensor is passed through a low-pass filter of the first order. The filter is supplied with a variable filter factor obtained from the absolute value of the measured value rate of change. The filter factor may be corrected by multiplying it with a correction value obtained from one of the ic engine operating parameters, e.g. the engine speed or the speed and the engine load. ADVANTAGE - Uses simplified digital signal processing circuit to provide exact result even during unsteady flow.