Exhaust emission control device of internal combustion engine

Abstract

To provide an exhaust emission control device of an internal combustion engine able to well atomize a reducing agent and ensure supply of combustion air. Since a controller of the exhaust emission control device also controls a nozzle opening degree of a variable geometry turbocharger for purpose of spraying a urea water, even in the state where the engine works in a low load range of Tto Twhere supercharging pressure normally can not be increased, supercharging pressure P suitable to atomization of the urea water can be obtained by controlling the nozzle opening degree of the variable geometry turbocharger to be closer to a closing side compared to the conventional art (shown by the chain double-dashed line), while the urea water can be securely atomized by a part of the supercharged air. Further, by increasing the supercharging pressure up to the value P, combustion air supplied to the engine is increased, therefore favorable combustion can be realized, and generation of particulates and exhaust of unburned fuel can be reduced.