Apparatus for controlling ignition timing in internal combustion

Abstract

An apparatus for controlling ignition timing in an internal combustion engine determines the amount of adjustment of ignition timing for preventing knocking with reference to the engine operating state. The amount of adjustment of the ignition timing carried out upon the detection of knocking is varied depending on the engine speed. Specifically, it is made large in the low speed region where the interval between successive firings is relatively long, thus increasing the speed with which knocking can be prevented and enhancing the protection of the engine from damage in this operating region. Also, rapid acceleration and other transient engine operating states are detected and a transient state adjustment is calculated separately of the adjustment amount for knocking prevention. The transient state adjustment is added to the knocking prevention adjustment and the result is used for retarding the ignition timing, whereby knocking can be effectively prevented during rapid acceleration. Further, after knocking has been prevented, the ignition timing is advanced with consideration given to reference knocking occurrence frequencies set independently for different engine operating conditions. Thus, the knocking occurrence frequency can be maintained at a fixed level irrespective of the engine operating condition, whereby the engine output can be optimized.