| 摘要 |
<p>PURPOSE:To measure the mean air flow rate of a pulsating air flow with high precision by providing a heating resistor on an upstream and a downstream air suction side and deciding the difference in radiant heat quantity between those heating resistors electrically. CONSTITUTION:A Wheatstone bridge consists of a heating resistor 2, a temperature probe 11a, and resistances 14 and 15 and a current to be flowed through the resistor 2 is adjusted by a differential amplifier 16 and a transistor (TR) 17 so that the potential difference at the mid-point of this bridge is '0'. This constitution control the resistance value of the resistor 2, i.e. temperature to a constant value regardless of the velocity of air. At this time, a signal generated by the resistor 2 corresponding to the velocity of air is as high as the potential at a point C. A heating resistor 3, on the other hand, constitutes a Wheatstone bridge together with a temperature probe 11b and resistances 18 and 19 as well as the resistor 2 and a signal generated by the resistor 3 corresponding to the velocity of air is as high as the potential at a point D. Further, the difference in potential between the points C and D is calculated by a differential amplifier 22, so that the output of the amplifier 22 is the signal of a flow meter using a hot-wire probe 10.</p> |
