| 摘要 |
PURPOSE:To enable knocks in all cylinders to be detected with a simple constitution by removing outputs caused by blow-out from variation component of discharge voltage signal to detect only variation component produced by voltage change during knocking. CONSTITUTION:An ignition coil 2 carriers out multiple discharge even in a period of knocking occurrence during the period of firing and combustion of mixture, for example, after ATDC 20 deg.. A detecting section 6 detects about 1/ 1,000 of this discharge voltage. The signals of the section 6 are passed through a band-pass filter centering 7.5KHz knock frequency by a knock processing circuit 7 and through a band-pass filter centering 15KHz frequency by a noise signal processing circuit 8. Also, said signals is passed through and processed by an integrating circuit to remove 50KHz rectangular wave noised caused by blow-out. Then said signals are subject to the subtraction of a knock signal correcting circuit 9 and leave only portions corresponding to the knock signal to be sent to the input of a knock judging circuit 10. Here, when they reach a level higher than a certain one, the knock is judged to take place so that ignition advancing angle is corrected. |
