Patent ID: 7324890

Claim:
An ignition timing control apparatus for an internal combustion engine having a plurality of cylinders, said apparatus comprising: a knock detection section that detects the occurrence of a knock in either of said plurality of cylinders; a reference ignition timing control section that sets reference ignition timing common to all of said plurality of cylinders; and a cylinder specific ignition timing setting section that sets cylinder specific ignition timings different from one another for said plurality of individual cylinders, respectively; wherein said reference ignition timing control section includes a reference ignition timing correction section that corrects said reference ignition timing in accordance with a detection state of occurrence of knocking; said reference ignition timing correction section corrects said reference ignition timing to a retard angle side when the occurrence of a knock is detected, but corrects said reference ignition timing to an advance angle side when the occurrence of a knock is not detected; said cylinder specific ignition timing setting section includes a cylinder specific correction value setting section that sets cylinder specific correction values to compensate for variations in cylinder specific optimum ignition timings of said plurality of individual cylinders, respectively; said cylinder specific ignition timing setting section sets said cylinder specific ignition timings based on said reference ignition timing in accordance with said cylinder specific correction values; said cylinder specific correction value setting section sets said cylinder specific correction values of the same number as that of said plurality of cylinders; and in a knock to knock occurrence period from the time of detection of a current knock occurring in any of said plurality of cylinders until the occurrence of the following knock is detected in either of said plurality of cylinders after a period of time in which the occurrence of a knock has not been detected in either of said plurality of cylinders, said cylinder specific correction value setting section sets, among said plurality of cylinder specific correction values, at least one cylinder specific correction value, which corresponds to a cylinder that has not yet reached a predetermined frequency of knock occurrences until the occurrence of said current knock, to an advance angle side value.