EXHAUST GAS CONTROL APPARATUS FOR INTERNAL COMBUSTION ENGINE (AS AMENDED)

摘要

It is possible to decrease the amount of NOx emitted into the air. The amount of ammonia adsorbed on an SCR catalyst is calculated by subtracting the amount of ammonium nitrate produced on the SCR catalyst from the amount of ammonia adsorbed on the SCR catalyst at the time of starting of an internal combustion engine, and the amount of NO2 flowing into the SCR catalyst is decreased when an NOx purification rate estimated from the amount of ammonia adsorbed on the SCR catalyst is less than a threshold value compared to when the NOx purification rate is equal to or greater than the threshold value.

主权项

1. An exhaust gas control apparatus for an internal combustion engine, the exhaust gas control apparatus comprising:
a selective reduction type NOx catalyst provided in an exhaust passage of the internal combustion engine and configured to reduce NOx with ammonia as a reducing agent; a supply device configured to supply ammonia to the selective reduction type NOx catalyst; a temperature sensor configured to measure or estimate the temperature of the selective reduction type NOx catalyst; an electronic control unit configured to:
(i) measure or estimate an amount of ammonium nitrate produced on the selective reduction type NOx catalyst; and(ii) calculate an amount of ammonia adsorbed on the selective reduction type NOx catalyst at the present time by subtracting the amount of ammonium nitrate produced on the selective reduction type NOx catalyst from the amount of ammonia adsorbed on the selective reduction type NOx catalyst at the time of starting of the internal combustion engine, and
(iii) decrease an amount of NO2 flowing into the selective reduction type NOx catalyst when an NOx purification rate estimated from the amount of ammonia adsorbed on the selective reduction type NOx catalyst at the present time is less than a threshold value, as compared to when the NOx purification rate is equal to or greater than the threshold value.