| 摘要 |
PURPOSE:To improve an accuracy of operation and a response characteristic by a method wherein a ceramic sensor pipe with a red heat light photoconductive element freely inserted therein is red heated by the combustion flame and the radiated red heat light is guided to the light receiving element and applied to the control unit as a terminal potential so as to terminate a feeding of the desired volume of fuel. CONSTITUTION:When the sensor pipe 21 with its one end closed is red heated by the inner flame of the combustion flame, a red heat light is radiated from the inner surface of the sensor pipe 21, and the red heat light is guided to the light receiving element 23 through the photoconductive element 24 to produce a terminal potential corresponding to a strength of the red heat light. The terminal potential corresponds to a strength of red heat light, i.e. an oxygen concentration, so that when the unit is set in a dangerous range of lack of oxygen, the control unit (not shown) is performed to terminate a feeding of the fuel. In this case, the sensor pipe is constructed such that a material having a high thermal capacity, i.e. ceramic material, to have a thin wall thickness, resulting in making a high response characteristic, stability and accuracy of operation in respect to the strength of the red heat light. |
