| 摘要 |
PURPOSE:To improve the reliability and accuracy of a two-cell electrochemical sensor with a leak hole by arranging the sensor cell of the sensor so that the cell reacts to an exhaust gas before and behind a trap, and obtaining a current value when the electromotive force of the sensor cell becomes zero as a smoke detection signal. CONSTITUTION:The heater 14 of the smoke trap 5 provided to a by-pass tube 4 is powered on to generate heat, thereby oxidizing the smoke in the exhaust gas. Teen the sensor cell 52 positioned between a measurement chamber 55 and the exit side of the trap 5 generates the electromotive force E. A pump cell 53 positioned between the measurement chamber 55 and an atmosphere, on the other hand, moves the oxygen in the measurement chamber 55 to the atmosphere side through pumping operation. Then when oxygen partial pressure is equal between both sides of the sensor cell 52, the movement quantity of the oxygen by the pump cell 53 is proportional to the oxygen density difference between the upstream side and downstream side of the by-pass pipe 4 and the electromotive force E is 0 at this time. Then the current pump current IP is detected and this value is proportional to the movement quantity of the oxygen by the pump cell 53, so the oxygen density difference of the trap 5 can be detected. |
