| 摘要 |
PURPOSE:To enable a flow rate sensor to be used in the exhaust gas atmosphere in an automobile by using a thermistor coated with an oxidative catalyst so that the characteristics are not changed even in an unburned gas. CONSTITUTION:The sensor unit 10 is composed of a thermistor element 11, an oxidative catalyst 12 covering its surface and a pair of lead wires 13 and 14, which are connected to, e.g., a pair of lead electrode surfaces 23 provided on a heat resisting electricity insulating board 21 having a hole 22 in the center. With the temperature of the thermistor element 11 raised by supplying power from the electrode surfaces 23, making the holding surface of the thermistor element 11 agree with the direction 24 of a gas stream to be detected causes the electric resistance of the thermistor element 11 to vary with the change in the gas stream. According to the resistance variation, the gas flow rate is detected. In this case the effect of the oxidative catalyst 12 causes the contaminative component in the exhaust gas to reburn at the thermistor surface, so that it is free from contaminants. |
