Apparatus for controlling ignition timing in an internal combustion engine

Claim 1

A spark ignition internal combusion engine comprising: an engine body; an intake system connected to the engine body; an exhaust system connected to the engine body; the engine body having an intake port capable of providing a swirl motion of intake air; a control valve arranged in said intake port for controlling the swirl motion; means responsive to operating conditions of the engine for operating the control valve so that it is selectively open or closed in accordance with the operating conditions of the engine; fuel injection means for injecting the fuel into the engine; means for calculating the air-fuel ratio of air-fuel mixture to be supplied to the engine, the air-fuel ratio being high when the control valve is closed, and being low when the control valve is open; means for correcting the calculated air-fuel ratio in accordance with engine conditions; means for operating the fuel injector means so that the calculated air-fuel ratio is obtained; means for storing a plurality of ignition timing data maps, said maps having a respective order of priority, which order is substantially determined in accordance with the air-fuel ratio in such a manner that the priority becomes higher as the air-fuel ratio becomes smaller; means for detecting a plurality of engine parmeters related at least to the air-fuel ratio; means for judging whether the parameters detected by the detecting means meet with the engine requirements; means for selecting a map which has the highest order of priority from among the maps judged by said judging means so that the detected parameters meet the engine requirements; means for calculating an ignition timing from the map selected by the selecting means; and means for controlling the ignition so that ignition occurs at the calculated timing.