| 摘要 |
<p>PURPOSE:To improve the accuracy of flow rate detection by setting resistance values and resistance temperature coefficients of respective resistances so that output voltages of the resistances are not affected by ambient temperature. CONSTITUTION:A hot wire resistance 11 which is arranged in an air suction passage and has a resistance value Ra and an output resistance 5 which has a resistance value R1 and a resistance temperature coefficient alpha1 are connected in series, a hot wire temperature compensating resistance 13a which has a resistance value RK and a resistance temperature coefficient alpha2, a 1st reference resistance 13b which has a resistance value R2 and a resistance temperature coefficient alpha2, and a 2nd reference resistance 14 which has a resistance value R3 and a resistance temperature coefficient alpha3 are connected in series, and those two series circuits are connected in parallel to constitute a bridge circuit. In this case, the resistance values and resistance temperature coefficients of the respective resistances are so set an equation holds for the ambient temperature (t) outside the air suction passage. Consequently, the accuracy of the flow rate detection can be improved by preventing the output voltage of the output resistance from varying even if the ambient temperature varies.</p> |
