Control device for internal combustion engine

A control device for an internal combustion engine which is provided with an EGR device recirculating, as EGR gas, a portion of exhaust gas of an internal combustion engine to an intake passage and delays an ignition timing of the internal combustion engine at the time of deceleration, the control device comprising:

• a cylinder-inflow EGR gas amount determination portion that determines a cylinder-inflow EGR gas amount of EGR gas flowing into a cylinder of the internal combustion engine;
• a misfire occurrence prediction portion that predicts whether a misfire occurs, based on the cylinder-inflow EGR gas amount and an operation state of the internal combustion engine;
• a misfire avoidance control portion that executes misfire avoidance control to avoid the misfire when the misfire occurrence prediction portion predicts the misfire;
• a misfire avoidance determination portion that determines whether the misfire is unavoidable even if the misfire avoidance control is executed;
• and
• an ignition delay restriction portion that restricts a delay in the ignition timing when the misfire avoidance determination portion determines that the misfire is unavoidable, wherein
• upon the misfire avoidance prediction portion determining that the misfire is unavoidable even if the misfire avoidance control is executed, the misfire avoidance control portion executes the misfire avoidance control in a state of the ignition delay restriction portion having restricted the delay in the ignition timing,
• the control device further comprises:
• a misfire limit EGR gas amount calculation portion that calculates a misfire limit EGR gas amount which is an upper limit of a normally-combustible cylinder-inflow EGR gas amount, based on the operation state of the internal combustion engine;
• a required misfire countermeasure effect amount calculation portion that calculates a required misfire countermeasure effect amount necessary for avoiding the misfire, based on a difference between the cylinder-inflow EGR gas amount and the misfire limit EGR gas amount;
• and
• an actual misfire countermeasure effect amount calculation portion that calculates an actual misfire countermeasure effect amount in a case of the execution of the misfire avoidance control,
• the misfire avoidance determination portion compares the actual misfire countermeasure effect amount and the required misfire countermeasure effect amount to determine whether the misfire is unavoidable.