| 摘要 |
PURPOSE:To enable to surely sense the drop of indoor oxygen concentration and improve the safety by a method wherein a signal sensing part, which can change the magnitude of signal to be able to sense in response to the kind of fuel, is provided in the control circuit of a solenoid valve installed in a fuel passage. CONSTITUTION:By opening a main cock 2, a power source switch 14 and an ignition switch 15 are turned ON to open a primary solenoid valve 3 and to ignite the gas supplied to a first burner 4. Due to the burning of the first burner 4, the electric current flows in a flame rod FL to allow for a comparator IC2 to transmit the oscillation of a comparator IC, to a transistor Q2 to keep the solenoid valve 3 ON by applying the current rectified by a rectifying part 10 through an output transformer T2 to the solenoid valve 3. At this time, because the rate of the flame for current drop to the drop of the oxygen concentration in the atmosphere surrounding the flame rod FL varies with the kind of the fuel to be burnt, the sensing of the combustion flame generated by various gases can be coped with by changing the sensing level to the suitable level for the kind of the gas to be sensed with the change-over switches 16 and 17 of the signal sensing part 10. |
