Method and apparatus for ignition system spark timing control during engine cranking

An apparatus for the control of an ignition system for a spark ignition internal combustion engine having an idle speed, said apparatus comprising:

• an engine cranking sensor for detecting a cranking condition wherein the engine is under cranking and generating a cranking condition signal indicative of the cranking condition;
• an engine revolution speed sensor for detecting cranking speed of the engine and generating a cranking speed signal indicative of the cranking speed of the engine;
• and
• correction means, in response to the cranking condition signal and the cranking speed signal, for decreasing the value of spark advance in accordance with a drop in the detected cranking speed of the engine when the engine is under cranking and at the same time the detected cranking speed is lower than a predetermined value which is lower than the idle speed.

A method of controlling the ignition spark timing of an internal combustion engine having an idle speed comprising:

• detecting the revolution speed of the engine and generating a revolution speed signal indicative of the revolution speed of the engine;
• detecting a cranking condition wherein the engine is being cranked by detecting if the start switch of the engine is on, and a cranking condition signal indicative of the cranking condition,
• changing, in response to the revolution speed signal and the cranking condition signal, the spark advance of the engine in accordance with the detected revolution speed of the engine, by controlling the spark advance when
• (a) the engine is rotating between a zero and a first predetermined engine revolution speed which is lower than the idle speed during cranking, by retarding the spark advance proportionally to the actual revolution speed of the engine divided by said first predetermined engine revolution speed and
• (b) when the engine is rotating between said first predetermined engine revolution speed and a second predetermined revolution speed which is higher than said first predetermined engine revolution speed and higher than the idle speed, by maintaining the spark advance constant.

An apparatus for controlling the ignition spark timing of an internal combustion engine having a start switch and an idle speed, comprising:

• means for detecting the revolution speed of the engine and generating a revolution speed signal indicative of the revolution speed of the engine;
• means for detecting a cranking condition wherein the engine is being cranked, said means detecting if said start switch of the engine is on, said detecting means generating a cranking condition signal indicative of the cranking condition;
• means, in response to the revolution speed signal and the cranking condition signal, for changing the spark advance of the engine when it is being cranked in accordance with the detected revolution speed of the engine, said changing means controlling the spark advance when
• (a) the engine is rotating between a zero and a first predetermined engine revolution speed which is lower than the idle speed during cranking, by retarding the spark advance proportionally to the actual revolution speed of the engine divided by said first predetermined engine revolution speed and
• (b) when the engine is rotating between said first predetermined engine revolution speed and a second predetermined engine revolution speed which is higher than the idle speed, by maintaining the spark advance constant.