| 摘要 |
PURPOSE:To easily judge a knocking occurrence with composite judging for the knocking occurrence made possible by determining at least two resonance frequency components, included in the output of a vibration sensor, with the component range limited from a first crank angle to a second crank angle. CONSTITUTION:Vibration, produced by pressure variation following combustion in a combustion chamber, is caught with a knocking sensor 17 fitted in the vicinity of the combustion chamber, is outputted as an electric signal, and is inputted in a CPU in a control unit 9 via an amplifier and an AD converter. AD conversion is made at given time intervals in a given period, these AD conversion results are successively stored in a RAM, a frequency analysis requesting flag is sent to the CPU at the point of time when a converted number becomes (n), and frequency analysis is made with the CPU. Analyzed results including specific frequencies are selected and extracted from the frequency analysis result, and (m) results are added in order of the larger sizes of components. A knocking occurrence is recognized when an added result is compared with a mean value at the time of the knocking occurrence and found to have a ratio of a given value or more. |
