| 摘要 |
PURPOSE:To aim at enhancing the control accuracy of the ignition timing with no timing circuit exclusively used for energizing an A/D converter, by providing such an arrangement that the output of a knock sensor is taken into over a predetermined time period from the time point just after the time when a piston reached the top dead center, the A/D conversion of the peak-value of the above- mentioned output is initiated at the end of the predetermined time period, and the hold of the peak-value is reset after the A/D conversion. CONSTITUTION:A control circuit 34 digitally computes outputs from various sensors including a knock sensor 18 to control the ignition timing for an ignitor 28. The control circuit 34 is provided therein with a peak-hold circuit, a channel selecting circuit, etc. and takes thereinto the detection output of the knock sensor 18 over a predetermined time period from the time point just after the time when a piston 5 reaches the top dead center so that the peak-value of the detection output of the knock sensor 18 within the predetermined time period is held. Then at the end of the predetermined time period an A/D convertor for converting the peak-value is energized by means of the channel selecting circuit, and as well the peak-hold circuit is reset at the end of the A/D conversion. |
