| 摘要 |
<p>PURPOSE:To enhance the detection accuracy by deciding whether air is flowing forward or reversely and bringing a flow rate detection signal close to the actual flow rate of sucked air. CONSTITUTION:A heating resistor 30 and a temperature-sensitive resistor 31 are formed, respectively, in the upstream and downstream on an insulating board. A bridge circuit 33 is formed including the heating resistor 30 and a bridge circuit 37 is formed including the temperature-sensitive resistor 30. When the bridge circuit 37 detects a forward air flow, a selection circuit 44 delivers a flow rate voltage V1 from the bridge circuit 33 as output voltage Vout. A constant voltage V00(voltage value zero) from a constant voltage circuit 43 is selected in case of reverse air flow. In case of the reverse air flow, the output voltage Vout is restrained from becoming negative and brought close to the actual air flow rate thus realizing high accuracy detection.</p> |
