| 摘要 |
PROBLEM TO BE SOLVED: To provide a smoke sensor which prevents malfunction due to drops of water entering the sensor and also prevents the rate of air flowing into a smoke sensor chamber from decreasing. SOLUTION: The body of the smoke sensor is in a shape of a bottomed cylinder and fitted to a ceiling with an opening facing upward. In the bottom wall of the body 3, a storage recessed part is formed by recessing a nearly center part of the reverse surface and in this storage recessed part 4, a protection cover 8 holding a smoke sense part A is fitted by inserting the upper end part. The smoke sensor part A is equipped with a smoke sense chamber S that external smoke is allowed to enter and a circuit board 5 where a smoke sense circuit sensing the smoke entering the smoke sense chamber S is formed; and the circuit board 5 is arranged in the storage recessed part 4 and held on the protection cover 8 while the smoke sense chamber S is exposed to the lower side from the storage recessed part 4. A water drain hole 14 which discharges water flooding in the body 3 to the outer side through the storage recessed part 4 is bored penetrating a part of the side wall 4a of the storage recessed part 4 below the circuit board 5. COPYRIGHT: (C)2003,JPO
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