Hot-wire type air flow meter for internal combustion engine

摘要

The invention relates to an air flow meter for an internal combustion engine having an exothermic resistor film (11, 211) provided on a thin portion formed on a silicon substrate and a control circuit (220) for controlling a voltage to be applied to the resistor film (11, 211) or a current to be supplied. The resistor film (11, 211) is arranged in a suction pipe of the internal combustion engine and heat is emitted to an air through the resistor film (11, 211). In the case where a liquid droplet is deposited onto the resistor film (11, 211), the control circuit (220) controls the applied voltage to a value smaller than a voltage which is applied to the resistor film (11, 211) at the time of measuring a maximum specified measuring range or controls the supply current to a value smaller than a current flowing in the resistor film (11, 211) at the time of measuring the maximum specified range.