| 摘要 |
PURPOSE:To obtain an optimum prepurge time with a simple means by a method wherein a clockpulse cycle is shortened in accordance with a prepurge completion signal which is provided from a combustion control element into which clockpulses, flame existence discrimination signals and the like are inputted. CONSTITUTION:An integrated circuit 1 for combustion control is provided with an input terminal FD(-) connected to a flame detecting circuit 3, an input terminal CLK for inputting time counting clockpulses, and output terminals FAN, IGN and SV respectively for driving an air blower, ignitor and fuel valve. The circuit 1 includes a timer means for counting the clockpulses and a control means for successively driving the air blower, ignitor and fuel valve in accordance with the output of the timer means. A clockpulse switching circuit 20 is constituted by providing a frequency dividing circuit IC21 which duplicates the cycle of the clockpulse from a terminal 8 of a power source circuit 5. The circuit 20 is adapted to switch the clockpulse in accordance with the output from the output terminal IGN or SV. |
