| 摘要 |
An exhaust gas control apparatus for an engine (1) is provided with a urea water supply mechanism (200) adding urea water to exhaust gas, a SCR catalyst (41) adsorbing ammonia and removing NOx by using the adsorbed ammonia, and a control device (80) controlling a urea water addition amount based on a target adsorption amount for the ammonia adsorbed onto the SCR catalyst. The control device executes a first processing for acquiring a parameter correlated to the time period during which the temperature (THEH) of the SCR catalyst is equal to or higher than a threshold (DT) and an initialization processing for decreasing the amount of the ammonia adsorbed on the SCR catalyst on a condition that said parameter acquired in the first processing is equal to or higher than a predetermined value (HS1). |
