JPS6424163A - Knock control device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of knock and the worsening in fuel consumption rate by carrying out the retard correction of ignition timing based or the output of a knock sensor when the knock sensor is normal, on the other hand, by carrying out the retard correction as much as a specified amount in the operating range at the time of knock occurrence when the knock sensor is abnormal. CONSTITUTION:The knock of an internal combustion engine is detected by a knock sensor (a), and further whether the knock sensor (a) is normal or not is judged by a means (b). And when a knock is detected, the ignition timing of the internal combustion engine is set by a first means (c) to a delayed timing later than a basic ignition timing. On the other hand, the load condition of the internal combustion engine is detected by a means (d), and further when the internal combustion engine is in a specified high load condition, the ignition timing is set by a second means (e) to a delayed timing later than the basic ignition timing. And according to the result judged by the means (b), the first and the second means (c) and (e) are changed over alternately via a means (f). In other words, in accordance with whether the knock sensor (a) is normal or abnormal, the ignition timing is selectively determined on the basis of the outputs of the first and second means (c) and (e) respectively.