| 摘要 |
PURPOSE:To save power rates or to accomplish the elongation of the life of a power supply battery by defining the opening and closing sequence such that time differences are afforded to the opening and closing of two solenoid valves interposed in series, and one of both solenoid valves which has been closed earlier than the other at the time of closing operation of both solenoid valves is opened later than the other. CONSTITUTION:Out of two solenoid valves 3 and 4, one is formed into a power supply holding type, and the other into a self-holding type. By this organization, during the combustion operation of the burner 1, the fuel supply can be continued by supplying power for holding the open valve state, only to a second solenoid valve 24 of the power supply holding type thereby to save power consumption. Even if the closing operation of the first solenoid valve 3 of the self-holding type becomes impossible due to a failure of a power source circuit 8 or interruption of service, the fuel supply can be interrupted with automatic valve closure by the self closing actuating force of the second solenoid valve 4 of the power supply holding type. Thus, power consumption can be saved and safety against any power supply trouble can be secured.
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