| 摘要 |
PURPOSE:To enable to automatically and surely start the ventilating fan in association with the use of gas appliance by a method wherein a switching circuit for starting the ventilating fan is energized by the detected sound of gas flow in a gas piping connected to the gas appliance. CONSTITUTION:A microphone 1 used as a detecting unit to detect the sound of gas flow in the gas piping 9 connected to the gas appliance is tightly contacted to said gas piping 9 and fixed with a clip 10 together with a sound insulating material 11. The sound of gas flow collected with the microphone 1 is amplified at an amplifier circuit and, after that, the external noise in said sound is removed at an filter circuit 3 and then said sound is discriminated and detected at a discriminator circuit 4. The output of the discriminator circuit 4 is next sent to a switching circuit 5, by means of the actuation of which the fan motor of the ventilating fan is made to be put into operation. In such a manner as mentioned above, the interlocking operation of the ventilating fan in association with the use of the gas appliance can be ensured. |
