Idle control system of direct-cylinder-fuel-injection spark-ignition engine

An idle control system of an engine, comprising:

• intake air quantity adjusting means for adjusting an intake air quantity of the engine;
• temperature rise controlling means for setting an ignition timing to a basic ignition timing at or following a compression top dead center time, and for setting a fuel injection timing following the compression top dead center time and before the basic ignition timing, when the engine is operating in an idle state and a request is made to raise a temperature of a catalyst;
• target intake air quantity setting means for calculating an engine request torque and setting a target value of the intake air quantity in accordance with the engine request torque;
• limit value setting means for setting an upper limit value of the intake air quantity that is set to prevent an excessive rise in exhaust temperature;
• intake air quantity controlling means for controlling the intake air quantity adjusting means so that the intake air quantity becomes the target value when the target value is less than the limit value in controlling the temperature rise, and for controlling the intake air quantity adjusting means so that the intake air quantity becomes the limit value when the target value is greater than the limit value in controlling the temperature rise;
• and
• ignition timing controlling means for setting the ignition timing to be the basic ignition timing when the target value is less than the limit value in controlling the temperature rise, and for correcting the ignition timing towards a spark advance side from the basic ignition timing on the basis of insufficient air quantity when the target value is greater than the limit value in controlling the temperature rise.

A method of controlling an engine system, the engine system including an intake air quantity adjusting device for adjusting an intake air quantity of the engine, an igniting device for igniting a fuel supplied to the engine, a catalyst included in an exhaust system of the engine, and a controller configured to control the intake air quantity adjusting device and the igniting device, the method comprising:

• setting an ignition timing of the igniting device to a basic ignition timing at or following a compression top dead center time when the engine is operating in an idle state and a request is made to raise a temperature of the catalyst;
• calculating a target value of the intake air quantity in accordance with an engine request torque when the ignition timing of the igniting device is set to the basic ignition timing;
• calculating a limit value of the intake air quantity in accordance with a rate of increase of exhaust temperature;
• comparing the target intake air quantity with the limit intake air quantity;
• controlling the intake air quantity adjusting device so that the intake air quantity becomes the target value when the target value is less than the limit value and while the ignition timing is set to the basic ignition timing;
• and
• setting the ignition timing towards a spark advance side from the basic ignition timing based on a difference between the target value and the limit value when the target value is greater than the limit value and while the intake air quantity adjusting device is controlled to set the intake air quantity to become the limit value.

A control system of an engine, comprising:

• an intake air quantity adjusting device for adjusting an intake air quantity of the engine;
• an igniting device for igniting a fuel supplied to the engine;
• a catalyst included in an exhaust system of the engine;
• and
• a controller configured to control the intake air quantity adjusting device and the igniting device, wherein the controller:
• sets an ignition timing of the igniting device at or following a compression top dead center time when the engine is operating in an idle state and a request is made to raise a temperature of the catalyst;
• calculates a target value of the intake air quantity in accordance with an engine request torque;
• calculates a limit value of the intake air quantity in accordance with a rate of increase of exhaust temperature;
• compares the target intake air quantity with the limit intake air quantity;
• controls the intake air quantity adjusting device so that the intake air quantity becomes the target value when the target value is less than the limit value;
• and
• advances the ignition timing based on a difference between the target value and the limit value when the target value is greater than the limit value and while the intake air quantity adjusting device is controlled to set the intake air quantity to become the limit value.