| 摘要 |
PURPOSE:To obtain an automatic ventilating fan having a safe and simple structure, by insulating an ignition detecting circuit and a ventilating fan driving power circuit electrically from each other, and using no mechanically moved contacts in the ventilating fan driving power circuit to which a high voltage is applied. CONSTITUTION:In a three-legged leakage type transformer in which one leg of a three-legged iron core is an opened leg having a gas, a primary coil 4 connected to an AC power source 13 is wound around one of the remaining two non-open legs while a first secondary coil 6 the opposite ends of which are connected to a switch 6 that is closed when a combustion means is ignited is wound around the other non-open leg. Further, a second secondary coil 8 is wound around the open leg having a gap, and a contactless switching element 11 opened and closed in response to the output signal of the coil 8 is connected to the opposite ends of the AC power source 13. Since, by employing such an arrangement, the ignition detecting circuit and the ventilating fan driving power circuit are insulated electrically from each other, and in addition thereto, no mechanically moved contacts are used in the ventilating fan driving power circuit which is applied with a high voltage, it is enabled to ensure safe use of the ventilating fan. |
