Controlling device for internal combustion engine equipped with turbocharger

Abstract

A target first air amount for achieving a requested torque by an operation of an intake property variable actuator is calculated by using a first parameter. A target second air amount for achieving the requested torque by an operation of a turbocharging property variable actuator is calculated by using a second parameter. A value of a first parameter changes to a value that reduces a conversion efficiency of an air amount into torque in response to the requested torque decreasing to a first reference value or lower. Further, a value of the second parameter starts to change to a direction to reduce the conversion efficiency in response to the requested torque decreasing to a second reference value that is larger than the first reference value, or lower, and gradually changes to a direction to reduce the conversion efficiency in accordance with the requested torque further decreasing from the second reference value to the first reference value. The target air-fuel ratio is set at a first air-fuel ratio in a period in which the requested torque is larger than the first reference value, and is switched to a second air-fuel ratio which is leaner than the first air-fuel ratio in response to a decrease of the requested torque to the first reference value or lower.