Exhaust temperature raising apparatus and method for internal combustion engine

摘要

An exhaust temperature raising apparatus for an internal combustion engine includes an exhaust throttle valve that adjusts an amount of flow of an exhaust gas flowing in an exhaust passage, a valve control device for controlling the exhaust throttle valve to a substantially completely closed state at a time when an amount of an unburned fuel component contained in the exhaust gas is to be reduced, an engine air-fuel ratio control device for operating the internal combustion engine at a theoretical air-fuel ratio or a fuel-excess air-fuel ratio when the exhaust throttle valve is controlled to the substantially completely closed state by the valve control device, and a secondary air supply device for supplying a secondary air to an upstream portion of the exhaust passage when the exhaust throttle valve is controlled to the substantially completely closed state by the valve control device.