M. Karimifar (Iran) and K.E. Afshari (Canada)
Spark Ignition Engines, Knock Intensity
Optimal performance control of spark ignition engines has a great significance in today’s competitive automotive industry. Engine cylinder pressure data has been proven to be the most suitable control variable used, however the complexities in measuring and in the analysis of this signal are still under investigation. It has been shown in the literature that the best online performance control and the highest efficiency of spark ignition engines can be achieved if the engine is kept running just before ‘knock border line’ derived from the engine cylinder pressure signal analysis. In the current work, normal and knocking cylinder pressure data measured from a research variable compression-ratio engine over a wide range of operating conditions are studied. Both frequency and time domain analysis of the signals are extensively investigated and the results are compared. Effects of noise and interferences are also compared for both approaches. Frequency domain analysis of the experimental cylinder pressure data provided faster and easier procedure to detect knocking cycles and the engine performance was controlled more precisely.
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