| 摘要 |
PURPOSE:To afford a function for detecting trouble and malfunctioning of a flame detecting circuit, by employing such an arrangement that pulse signals are applied to a flame detecting comparison circuit and fuel supply is stopped when the intervals of the pulse signals produced from the comparison circuit are longer than the setting time of a timer incorporated in a fuel cut-off circuit. CONSTITUTION:When predetermined pulse signals are applied from a pulse generating circuit 2 to a comparison circuit CC, pulses are produced at an output terminal CC3 of the circuit 3. These pulses are detected by a pulse detecting circuit 3 and applied to a fuel cut-off circuit 4. Here, since the cut-off circuit 4 incorporates therein a timer (not shown) and the setting time of the timer is longer than the intervals of pulses detected by the pulse detecting circuit 3, the timer is reset under normal conditions. However, when some trouble is caused with the comparison circuit CC or other portions of the apparatus, potential at the collector of a transistor Tr1 is lowered and the output of the detecting circuit 3 is also lowered. Therefore, resetting of the timer is not caused, so that a solenoid valve is closed through operation of the cut-off circuit 4 and fuel supply is stopped. |
