| 摘要 |
<p>PURPOSE: To measure the average air flow rate of pulsating air flow accompanying counterflow by providing heating resistors on the upstream side and the downstream side of the air flow, and providing a temperature compensating resistor for electrically discriminating the difference between the diffusing quantities of heat of the heating resistors. CONSTITUTION: A Wheatstone bridge is constituted of a heating resistor 2, a temperature probe 11a and resistors 14 and 15. A current to the heating resistor 2 is adjusted with a differential amplifier 16 and a transistor 17 so that the potential difference at the midpoint of the bridge becomes zero. In this way, the resistance value of the resistor 2 is controlled so that the temperature has the constant value without using an air-flow speed. A heating resistor 3 constitutes a bridge by the same way as the resistor 2, and the current of the resistor 3 is adjusted with a differential amplifier 20. Therefore, the signal corresponding to the air-flow speed is the signal of a hot-wire type air flowmeter using a hot-wire probe when the difference of the potential is obtained with the differential amplifier 20. When the signal, which is inputted into a computer from this flowmeter, is converted into the air flow rate, the flow rate can be measured.</p> |
