Conventionally, ignition timing control is known as a technique for suppressing engine knocking and properly controlling engine operations by mounting a knocking sensor on an engine and controlling an ignition timing of the engine based on an output signal of the knocking sensor (see Patent Document 1).
In the ignition timing control, the ignition timing is advanced stepwisely when the occurrence of engine knocking is not detected by the knocking sensor; and the ignition timing is retarded when the occurrence of engine knocking is detected by the knocking sensor. This ignition timing control allows maximum use of engine output power while preventing engine knocking.
It is common in four-wheel vehicles to perform ignition timing control based on the output signal of the knocking sensor. On the other hand, simple-structure engines such as general purpose engines for small generators etc. and engines are equipped with electronic control units for control of engine operations such as engine rotation speed but are not generally equipped with knocking sensors. The ignition timing control is thus not currently preformed on the simple-structure engines for suppression of engine knocking.