| 摘要 |
PURPOSE:To make it possible to detect abnormality of a flame rod in its early stage, by detecting abnormality of the flame rod in accordance with the output of a flame detecting circuit and a prepurging signal. CONSTITUTION:If the flame rod 12 is operated normally, since the output of a NAND circuit 25 keeps an H-level, a microcomputer 20 detects that the flame rod is operated normally. On the other hand, if a short circuit is formed between a conductor 12a of the flame rod 12 and a combustion case of the burner due to deposition of carbon or the like, the output of the flame detecting circuit 24 becomes an H-level even during the sending of a prepurging signal (b). As a result, since the output of the NAND 25 becomes an L-level, the microcomputer 20 detects that there is abnormality in the operation of the flame rod 20, and the driving of the combustion system is stopped. Thus, abnormality of the flame rod can be detected in its early stage. |
