EXHAUST GAS CONTROL APPARATUS FOR AN INTERNAL COMBUSTION ENGINE AND CORRESPONDING CONTROL METHOD

摘要

An engine (1) is equipped with an SCR catalyst (41), a urea addition valve (230) that adds aqueous urea solution to an exhaust passage (28), a pressure sensor (260) that detects a pressure of aqueous urea solution in the urea addition valve (230), and a control device (80) that controls an amount of aqueous urea solution added by the urea addition valve (230). The control device (80) performs an addition amount correction process for correcting an amount of the aqueous urea solution added from the urea addition valve (230) such that the urea addition amount increases as the rate of decrease in the pressure of aqueous urea solution after the opening of the urea addition valve (230) decreases. The control device (80) reduces an increase correction amount for the amount of the urea added through the addition amount correction process as a temperature of a leading end of the urea addition valve (230) decreases.