Exhaust gas purifying system for internal combustion engine

摘要

It is an object of the present invention to provide an exhaust gas purifying system for an internal combustion engine in which the rise of the temperature of an HC adsorbent is adequately retarded to improve the purification of HC at the start of the engine. In an exhaust system of the internal combustion engine, there are provided a three-way catalyst provided in the downstream side of an exhaust manifold, an adsorbent-catalyst provided under the floor of an automotive vehicle and containing at least zeolite in its composition, and a catalyst provided in the downstream side of the adsorbent-catalyst. In particular, the heat capacity of an exhaust gas passage which connects between the three-way catalyst and the adsorbent-catalyst is increased greater than the heat capacity of the exhaust manifold. More particularly, the thickness of a wall of the exhaust gas passage is greater than that of the exhaust manifold. A substrate, a partition, or a muffler is provided across the exhaust gas passage. The exhaust tube in the exhaust gas passage has at least an inner side or an outer side thereof shaped to a convex and concave configuration.