| 摘要 |
<p>PURPOSE:To perform detection in such a state that the effect of the pulsation of a sucked air stream is avoided and to reduce power consumption, by detecting the flow amount of the sucked air stream from the supply time of a current to the hot-wire resistor cooled corresponding to the amount of sucked air. CONSTITUTION:The circuit for setting the voltages of reference resistors 14, 15 is connected to a series circuit of a hot-wire resistor 11 and a reference resistor 12 while a current supply time control means, which consists of the power transistor of a switching means for the ON/OFF-operation of current supply, the oscillator 20 of detection start signal generation means, the comparator 16 and FF18 of a detection finish signal generation means and first - third transistors 23, 26, 31, is provided. The flow amount of sucked air is detected from a current supply time before the voltages at the non-reversal side terminal and a reversal side terminal of the comparator 16 become almost equal. By this method, detection is performed without necessitating an A/D converter and receiving the effect of the pulsation of a sucked air stream and power consumption can be reduced.</p> |
