| 摘要 |
PURPOSE:To improve the precision at the time of a low flow rate by storing the last detection result as a substitute when the period of the output signal of a Karman vortex flow meter is longer than a specific period and storing the current detection result when shorter, and calculating an air flow on the basis of the storage contents. CONSTITUTION:A processor 21 detects the period Tn of a signal (d) with a period corresponding to the output signal (a) of the Karman vortex flow meter 13 every time a pulse signal (d) from a comparator 19 becomes 1, and when it is judged that the engine is in an idling state on the basis of the output signal (e) of an opening extent detector 18, it is judged whether the period Tn is longer than a reference period T (period in idling). When the period is longer, the period Tn-1 detected last is stored as the current period in memory 24 and the mean value AT of the period of the signal (d) from when the rotating angle of a crank shaft is 180 deg. CA and 360 deg. CA up to now is calculated. Further, the processor 21 calculates the intake air flow Q from an equation on the basis of output signals (f) and (g) of a crank angle sensor 20 every time a rotational angle position attains to 180 deg. CA and 360 deg. CA. |
