Exhaust gas purification system of internal combustion engine

Abstract

In an exhaust gas purification system having an oxidation catalyst and an exhaust gas purifying unit formed so as to include a filter and a selective reduction-type NOx catalyst, at least one of supply of the fuel component and supply of ammonia or an ammonia precursor in an amount that is increased when a prescribed condition under which a part of a fuel component supplied to exhaust gas passes through to a downstream side of the oxidation catalyst is satisfied as compared to a non-passing time supply amount that is a supply amount of ammonia or the ammonia precursor to be supplied when the prescribed condition is not satisfied is controlled such that ammonia for NOx selective reduction by the increased ammonia or ammonia precursor reaches the exhaust gas purifying unit before the passed fuel component. Accordingly, an effect of a fuel component supplied to exhaust gas on a NOx purification performance of the selective reduction-type NOx catalyst is minimized in the exhaust gas purification system of the internal combustion engine which includes the filter and the selective reduction-type NOx catalyst.