| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect a pressure vibration generated by pre-ignition distinguishing from another vibration by comparing the magnitudes of the detected vibration components of a plurality of frequency regions with a preset threshold value. SOLUTION: A vibration detecting sensor 5 detects the vibration along the frequency regions of, e.g. 1-10kHz, and transduces the vibration into electric signals. From these electric signal, the vibration components in the narrow bandwidths of, e.g. 8.0kHz and 4.5kHz are separated by BPFs 61 and 62. The electric signals passing through the BPFs 61 and 62 undergo amplifications 63 and 64 and A/D conversions 71 and 72, respectively, and the high-region side detected signal and the low-region side detected signal are inputted to an operating part 3. In the operating part 3, the magnitudes of these signal components are compared with a threshold value set by a vibration-component comparing means beforehand. When there are a plurality of the vibration components, which are generated at the magnitudes larger than the threshold level, including the vibration components other than the frequency region of the vibration components that are intrinsic to knocking, it is judged that a pre-ignition is generated in a combustion chamber. |
