| 摘要 |
PURPOSE:To detect exactly density of smoke in a discharged gas with a small power consumption by controlling intermittently quantity of conducting electricity to a heater of a smoke sensor. CONSTITUTION:As for a smoke sensor, a pair of platinum electrodes 2a, 2b are formed on the surface of an alumina substrate 1, and a heating element 4 is provided on the rear side, and smoke quantity is detected by measuring electric resistance between the electrodes. This smoke sensor is installed to a gas discharging pipe in which a discharge gas of 200 deg.C flows, and measurement time (time when the sensor is operated) t1, time t2 for making electricity conduct to the heating element, and the time t2 for radiation-cooling between the electrodes are set by using a program timer. A voltage applied to the heating element 4 is set so that the maximum temperature between the electrodes in the course of electric conduction becomes >=550 deg.C, and the electric conduction is executed for a short time in order to reduce the power consumption. According to such a constitution, the smoke deposited between the electrodes is heated and removed easily at every prescribed time, and the density of smoke in the discharged gas can be detected exactly. |
