Engine operating parameter control apparatus

Abstract

A control apparatus for an internal combustion engine capable of using as a fuel a regular (low-octane) gasoline, a premium (high-octane) gasoline, or a mixture of both type of gasolines. The engine produces knocks when the ignition timing is advanced beyond a reference ignition timing determined as a function of the type of gasoline being used. This ignition timing control apparatus detects the knocks, and provides as an output therefrom a signal according to the occurrence rate of the knocks which essentially indicates the type of gasoline in use. By means of this signal, this ignition timing control apparatus continuously displaces the reference ignition timing in the direction of retard angle by using a proportion factor calculator and an interpolator. At the same time, the displaced reference ignition timing is corrected by the detected knock signals on a real time basis. In addition to the ignition timing control, an operating parameter for the engine such as a supercharging pressure, a compression ratio, or an air/fuel ratio is controlled to suppress knocks by the displaced reference control value and/or the corrected control value. The combined ignition timing signal and operating parameter signal serve to energize an ignition coil and an actuator to suppress the occurrence of knocks. This operation will continue until no knocks occur.