Control device for internal combustion engine

A control device for an internal combustion engine applied to a vehicle, the control device comprising:

• at least one electronic control unit configured to
• i) execute idle control for controlling a rotation speed of a crankshaft of the internal combustion engine to reach a target speed for an idle operation,
• ii) decrease a first torque when the rotation speed of the internal combustion engine becomes equal to or less than a predetermined speed during the execution of the idle control, the first torque being a torque applied to the crankshaft of the internal combustion engine by a predetermined auxiliary machine mounted on the vehicle,
• iii) during the execution of the idle control,
• a) acquire a second torque, the second torque being a maximum torque that the internal combustion engine is capable of generating,
• b) acquire a third torque, the third torque being a load torque related to the internal combustion engine including the first torque, and
• c) acquire a fourth torque, the fourth torque being a maximum value of a shaft torque capable of being realized in the internal combustion engine, and
• iv) when the idle control is executed based on the second torque and the third torque, set the predetermined speed to be greater when a torque difference is equal to or less than a predetermined value compared to when the torque difference exceeds the predetermined value, the torque difference being a value obtained by subtracting the first torque from the fourth torque.