| 摘要 |
PURPOSE:To make it possible to optimize the ignition timing of an engine, by controlling the spark advance in accordance with the value of spark advance having such a characteristic that spark retardation is made as the load is increased, exceeding a spark advance value for high octane number fuel only when the octane number of fuel is below a predetermined octane number and upon judgement of knock controlling range. CONSTITUTION:An electronic control circuit 38 judges whether the octane number of used fuel is higher than a predetermined octane number or not, that is, whether the fuel is regular gasoline or not in accordance with the knocking condition of an engine which is indicated by a signal from a knocking sensor 32, and further, judges whether the engine is operated in a knock controlling range or not. When it is judged that a low octane number fuel is used and the engine is operated in the knock control range, the ignition timing is controlled in accordance with the value of a second spark advance having a characteristic which is subjected to spark retardation in accordance with the load of the engine. Accordingly, even if regular gasoline is used in a gasoline engine specified to be used with high octane number fuel, optimum operation may be obtained over the entire operating range. |
