Method for detecting combustion knock from the ionic current in an internal combustion engine

A method of detecting knocking combustion in an internal combustion engine having at least one combustion chamber operating in a succession of combustion cycles, comprising the following steps carried out for a respective present cycle of said combustion cycles:

• a) sensing an ionic current in said combustion chamber and providing an ionic current signal corresponding to said ionic current;
• b) processing said ionic current signal by sampling during a time window and filtering through a band-pass filter to provide a filtered sampled signal;
• c) integrating said filtered sampled signal to provide a present cycle integrated value;
• d) comparing said present cycle integrated value to a lower knocking threshold and to a higher knocking threshold that is higher than said lower knocking threshold;
• e) if said comparing determines that said present cycle integrated value does not exceed said lower knocking threshold, then providing a non-knocking signal indicating that knocking combustion has not been detected;
• f) if said comparing determines that said present cycle integrated value exceeds said lower knocking threshold and does not exceed said higher knocking threshold, then providing a knock recognition signal indicating that knocking combustion has been detected;
• and
• g) if said comparing determines that said present cycle integrated value exceeds said higher knocking threshold, then performing one of the following substeps:
• g1) providing said non-knocking signal, and
• g2) continuing to provide whichever one of said knock recognition signal and said non-knocking signal that was provided during a preceding one of said combustion cycles immediately preceding said present cycle.