Air Flow Meter/Sensor: Description and Operation

PURPOSE/OPERATION
The volume air flow sensor is integrated in the air cleaner to measure the intake air flow rate by using the Karman vortex phenomenon. The Karman vortexes are those which are symmetrically and regularly generated in the downstream from the triangular pillar when the pillar is placed in the air stream. The generation rate of vortexes is proportional to the air flow rate. The volume air flow sensor uses ultrasonic waves to convert the generation rate of vortexes into the pulse signal which is proportional to the air flow rate, and inputs the signal to engine control module which calculates and determines the standard injection time from the intake air flow rate signal and the engine revolution speed signal (crankshaft position sensor signal.)