| 摘要 |
PURPOSE:To make a positive and stable sensing of combustion flame even if the combustion flame is swung due to air or the like by a method wherein light from the combustion flame is guided to a light receiving element through an optical fiber. CONSTITUTION:Light generated by combustion flame of a burner 1 is guided to a phototransistor 3 through an optical fiber 2. While the burner 1 keeps an ignited condition, the phototransistor 3 keeps its conducted condition, a delay circuit 4 constituting a signal processing circuit B generates an instruction signal so as to keep an opened condition of a solenoid valve arranged in fuel supplying passage for the burner 1 in respect to a colenoid valve opening and closing control circuit C. In turn, when the combustion flame of the burner 1 is diminished accidentally under an influence of wind or a lack of oxygen, the phototransistor 3 becomes non-conductive, the solenoid valve opening and closing control circuit C closes the solenoid valve and then the supplying of fuel to the burner 1 is automatically stopped. |
