| 摘要 |
PURPOSE:To improve a response characteristic and provide a positive operation of the unit by a method wherein an oxygen concentration sensor is constructed such that a photoconductive element is loosely inserted into the sensor pipe and further connected to the light receiving element and a feeding of fuel is terminated when the output of the light receiving element is set in a predetermined range. CONSTITUTION:When a leading end of the sensor pipe 21 of the oxygen concentration sensor 13 is heated by the inner flame of the combustion flame to generate a red heat condition, the inner surface of the sensor pipe 21 is also red heated to radiate the red heat light, and the red heat light is introduced into the light receiving element 23 through the photoconductive element 24. The light receiving element 23 produces a terminal potential in response to the strength of the red heat light. Thus, when the terminal potential is set in a predetermined dangerous range of lack of ocygen, the fuel feeding signal is produced from the control unit (not shown) to terminate the supplying of the fuel. With this arrangement, it is possible to provide a simple structure and a good response characteristic, a positive operation and further to improve a safety of the unit without being affected by the soot and the like. |
