| 摘要 |
PURPOSE:To perform correct knock judgment over the whole rotating speed region of an engine by attenuating the knock signal of the engine to 1/2<n> and making this damping action effective only under required conditions with large vibration of the engine. CONSTITUTION:The knock signal detected by a knock sensor 11 is inputted to an attenuator 20 via a BPF 12. On the other hand, the rotation signal detected by a distributor 17 is inputted to a microcomputer 16 via a wave-form shaping circuit 18. The microcomputer outputs a signal making the attenuator 20 effective only at the required time, the digital signal to be sent to a ladder resistor 15 is shifted down by the attenuation quantity when the attenuator 20 is made effective, i.e., (1/2<n>) for (n) shift down. The output signal of the ladder resistor 15 is inputted to a comparing circuit 13 via a buffer 14. The comparing circuit 13 outputs the noise pulse and the knock judgment pulse, the microcomputer 16 judges the knock based on the knock judgment pulse. |
