Patent ID: 8666635

Claim:
A control device for an internal combustion engine, comprising: required torque determining means that determines a required torque, which is a required value of torque generated by an internal combustion engine; required air-fuel ratio determining means that determines a required air-fuel ratio, which is a required value of an air fuel ratio of a mixture gas provided for combustion; target air quantity calculating means that calculates a target air quantity for realizing the required torque under the required air-fuel ratio, based on data set by linking a relationship of an air quantity and torque in an optimal ignition timing to an air-fuel ratio; air quantity control means that manipulates an actuator for air quantity control in accordance with the target air quantity; fuel injection quantity control means that manipulates an actuator for fuel injection quantity control in accordance with the required air-fuel ratio; torque estimating means that estimates an air quantity which is realized by operation of the actuator for air quantity control, and estimates torque which is realized by the estimated air quantity under the required air-fuel ratio, based on data set by linking a relationship of an air quantity and torque in an optimal ignition timing to an air-fuel ratio; and ignition timing control means that controls an ignition timing to compensate for a difference which occurs between the estimated torque and the required torque by an ignition timing when a predetermined permission condition is satisfied, and keeps the ignition timing at an optimal ignition timing when the permission condition is not satisfied, wherein the required air-fuel ratio determining means comprises required air-fuel ratio calculating means that receives a requirement concerning exhaust gas performance of the internal combustion engine, and calculates an air-fuel ratio which satisfies the requirement as a required air-fuel ratio, change speed lessening means that processes a signal of the required air-fuel ratio calculated in the required air-fuel ratio calculating means to lessen a change speed thereof, and final determining means that determines the required air-fuel ratio the change speed of which is lessened by the change speed lessening means as a final required air-fuel ratio when a predetermined lessening condition is satisfied, and determines the required air-fuel ratio calculated in the required air-fuel ratio calculating means as a final required air-fuel ratio when the lessening condition is not satisfied, the permission condition includes the required air-fuel ratio calculated in the required air-fuel ratio calculating means changing in a rich direction, and a change amount thereof being larger than a predetermined determination reference value, and the lessening condition includes the change amount of the required air-fuel ratio calculated in the required air-fuel ratio calculating means being larger than the determination reference value, and the permission condition being unsatisfied.