Moving Windows algorithm to evaluate the knock in spark ignition engine

Siemens Automotive (VDO) algorithm is widely used in the evaluation of knock. But VDO algorithm can´t evaluate the intensity accurately when the knock occurs earlier than the peak pressure. An algorithm based on VDO algorithm to evaluate the knock has been developed, and is called Moving Windows algorithm. Moving Windows algorithm uses two moving windows of the same width to analyze the high frequency pressure oscillation in a specified crank angle period. The high frequency pressure oscillations´ energy in one window can be evaluated by the integral of the modulus of the high frequency pressure oscillations. The knock indicators ΔK_max and K_I of the Moving Windows algorithm were determined by comparing the two moving windows´ energy. The Moving Windows algorithm can detect the start point of the knock, and its knock intensity indicators have better accuracy than that of the VDO algorithm.