| 摘要 |
PURPOSE:To decrease the error in measuring oxygen concn. and to prevent the false announcement of warning for lack of oxygen, etc. by providing a means for changing over the rate of combustion, changing over forcibly an ion current value to the preset rate of combustion, executing combustion and measuring the oxygen concn. after lapse of the specified time. CONSTITUTION:The means 11 for changing over the rate of combustion consisting of, for example, an electromagnetic pump and an oscillation circuit for controlling the operating speed thereof, etc. is connected to a microcomputer 10 of a detector. The ion current flows when a flame is formed between a burner head 3 and a flame rod 1 by operating an ignition switch. The ion current is converted to a voltage signal A by a resistor 6 and said signal is passed through a protective resistor 7 and is thus made to the voltage signal B which is inputted to the microcomputer 10. The microcomputer 10 counts the time from the start of the combustion upon receipt of the input signal C and feeds the signal E to the means 11 after the prescribed time to increase the rate of combustion to strong combustion for the specified period. The ion current to be used as a reference is measured upon lapse of the prescribed time and is stored in a storage device. The exact detection of the oxygen concn. is thus made possible. |
