| 摘要 |
PURPOSE:To enable easy and reliable discriminating of the presence of knocking, by a method wherein a difference in level between a signal component of a knocking frequency and a signal component of a noise frequency at the high- pass side of the frequency. CONSTITUTION:Vibration due to combustion explosion of an internal combustion engine is detected by a piezo-electric element 1, and the output signal thereof is inputted to a reducer 3 via a filter 2a, extracting a signal of a knocking frequency (7.5-8.5K Hz), and a filter 2b for extracting a noise frequency (9- 10K Hz) at a high-pass side of the knocking frequency. A level difference signal between the two signals is compared with a reference level by a comparator 4, and if the level difference exceeds 4dB, a knocking pulse is inputted to a counter 7 via an AND circuit 5 in synchronism with a signal of a timer 5, and a counting value is displayed in a displaying device 8. This causes reliable discriminating of the presence of knocking. |
