| 摘要 |
PURPOSE:To enable knock in high speed rotation of an engine to be controlled by controlling ignition timing when detected value of rotational frequency of the engine is larger than a predetermined value even if a knock sensor generates small knocking indicating signals, similarly to when large knocking indicating signals are generated. CONSTITUTION:In a crank angle wherein electric signals from a knock sensor 12 produce only mechanical vibration caused by valve blows or the like other than knocking without the occurrence of the knocking, the output amplitude b from the knock sensor 12 is taken out as background signal and multiplied by predetermined factors k1-k2, for example, k2=2k1 to provide judgement level of larger or smaller knock. Since these (b), (k1b), (k2b) change together in response to the rotational frequency of an engine, a point P for example represents small knocking between b and c as viewed from the output of the sensor 12. However it represents actually large knocking since it exceeds d. Thus, a control circuit 20 controls ignition timing even when the signals of the knock sensor 12 represent small knocking in high speed rotation of the engine, as well as when they represent large knocking. |
