| 摘要 |
PURPOSE:To prevent the occurrence of explosion ignition, by a method wherein, when the terminal voltage of the battery source of an ignitor is decreased to a value lower than a given value, an electromagnetic safety valve situated in a gas feed passage is closed. CONSTITUTION:When the terminal voltage of a battery source 20 exceeds a given value by, for example, 0.8V, the spark frequency of an ignitor 15 exceeds, for example, 1Hz at which there is a fear of explosion ignition occurring, and the energizing current of an actuating solenoid 10 exceeds a holding current of, for example, 100mA. Thereby, an electromagnetic safety valve 19 is held in an opening state, and a main burner 3a, a pilot burner 3b, and an ignition burner 3c are normally ignited. When the terminal voltage of a battery source 20 is below 0.8V, the spark frequency of the ignitor 15 is decreased to 1Hz or less. Since an energizing current to the actuating solenoid 10 is controlled to 10mA or less by means of a valve closing means 23, for example, a series connection circuit of a diode 24 and a resistor 25, the electromagnetic safety valve 19 is closed and live gas is not delivered therefore the main burner 3b, the pilot burner 3b, and the ignition burner 3c are not ignited to ensure safety. |
