Idling speed control method and apparatus for an internal combustion engine

In an idling speed control system for adjusting an amount of intake air supplied to an internal combustion engine by controlling an engine output torque so that engine speed matches a target speed when the engine is idling, an idling speed control method comprising the steps of:

• (a) determining a stroke period of the engine;
• (b) determining an instantaneous value of the determined stroke period;
• (c) subjecting the determined instantaneous value to first order delay processing to obtain a second value;
• (d) predicting a torque correction factor, indicative of excess or deficiency of an engine output torque due to a response delay in an intake system of the engine, from a ratio of the determined instantaneous value of step (b) to the obtained second value of step (c);
• and
• (e) controlling the engine output torque in accordance with the predicted torque correction factor of step (d).

In an idling speed control system for adjusting an amount of intake air supplied to an internal combustion engine by controlling an engine output torque so that engine speed matches a target speed when the engine is idling, an idling speed control method comprising the steps of:

• (a) determining a speed of the engine:
• (b) determining an instantaneous value of the determined engine speed;
• (c) subjecting the determined instantaneous value to first order delay processing to obtain a second value;
• (d) predicting a torque correction factor, indicative of excess or deficiency of an engine output torque due to a response delay in an intake system of the engine, from a ratio of the determined instantaneous value of step (b) to the obtained second value of step (c);
• and
• (e) controlling the engine output torque in accordance with the predicted torque correction factor of step (d).

In an idling speed control system for adjusting an amount of intake air supplied to an internal combustion engine by controlling an engine output torque so that an engine speed matches a target speed when the engine is idling, an idling speed control apparatus comprising:

• first means for detecting a value of a predetermined parameter representative of a rotation state of an engine output shaft;
• second means for predicting a torque correction factor, indicative of excess or deficiency of an engine output torque due to a response delay in an intake system of the engine, in accordance with the detected value of the predetermined parameter;
• and
• third means for controlling the engine output torque in accordance with the predicted torque correction factor, wherein an instantaneous value of the predetermined parameter is further detected by the first means, and the second means subjects the detected instantaneous value to first order delay processing, determines a ratio of the instantaneous value of the predetermined parameter to a value obtained by the first order delay processing, and predicts the torque correction factor in accordance with the determined ratio.