Knock control system for internal combustion engines

Claim 1

A knock control system for use with an internal combustion engine comprising: a knock sensor for detecting knock produced by the internal combustion engine; knock discriminating means for discriminating knock based on an output signal from said knock sensor; processor means responsive to the result of knock discrimination for computing a control value to control a knock control factor for the internal combustion engine and for changing the knock control factor according to the computed control value; detector means for detecting a maximum value of the output signal of said knock sensor during a prescribed period; discrimination level setting means for setting a knock discrimination level for use in said knock discriminating means; corrective level setting means for setting at least two corrective levels to correct said knock discrimination level set by said discrimination level setting means; comparator/counter means for comparing said maximum value of the output signal of said knock sensor with said at least two corrective levels and counting occurrences in which said maximum value exceeds said corrective levels; and level correcting means for correcting said knock discrimination level dependent on the counts of such occurrences.