| 摘要 |
PURPOSE:To detect the condition of flame when the flame assumes an incomplete flame standing condition so as to enable prevention of an extraordinary combustion by providing a second flame rod which detects a flame standing condition at the upper part of a first flame rod which carries out the detection of normal combustion flame. CONSTITUTION:When a slight flame standing occurs, the combustion flame hits against a second flame rod 23. Therefore, a flame current flows between the flame rod 23 and the burner 11, and charging to a capacitor 29 is started. When the charging advances to a reference potential determined by resistors 31 and 32, the output of a comparator 35 for a second detection circuit is inverted and assumes a low level so as to prevent the flame current from flowing between the first flame rod 7 and the burner 11. As a result, the charging potential of the capacitor 18 is lowered, and the input relation of a comparator 20 for the first detection circuit becomes + input > - input and the output thereof is inverted, and the comparator 21 does not supply a combustion detection signal to a combustion control circuit 21. Accordingly, the device assumes a non-ignition detection state, and the combustion control circuit 21 acts to stop the combustion in a predetermined sequence. |
