| 摘要 |
PURPOSE:To enhance safety by providing a pilot flame detection circuit utilizing a safety timer circuit and a thermocouple. CONSTITUTION:With an oil supply cock opened and an operation switch turned on, a switch SW129 turns on, an ignition transformer 20 and the solenoid valve 21 (gas main valve) turn on through the functions of relay contacts 19 and 14, and ignition action is started. Detecting this, a thermocouple 3 generates thermoelectric power. When the potential at a connection point 7 has exceeded that at a connection point 6, current supply for the transformer 20 is stopped, but the pilot flame is sustained because the valve 21 is kept on. At the same time, a load circuit is fed with current and a main burner 30 starts burning. With the pilot flame out, the electromotive force of the thermocouple 3 falls so that the valve 21 is closed and the gas supply is cut off. When the pilot flame is not sustained in a preset time period, a safety timer circuit 1 stops the current supply for the transformer 20 and the valve 21. |
