Knock control apparatus for internal combustion engine, returns normal ignition timing retard based on cylinder failure judgments detected from output of background level setting unit and retard angle changing unit

摘要

A retard angle changing unit (43) changes retard angle of failure cylinder based on output from knock suppression unit (3), fail judgment unit (41) and number of failure cylinder judgment unit (42). Normal judgment returning unit (44) returns normal ignition timing when cylinder under judgment for failure meets normal judgment requirements based on output from background level setting unit (2) and retard angle changing unit (43). Knock control apparatus has fail controller (4) comprising judgment unit (42) for judging number of failure cylinder based on output from judgment unit (41) which judges each cylinder failure based on output from background level setting unit (2) and knock suppression unit (3).