Abstract: 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.

Abstract: In an exhaust system of the internal combustion engine, there are provided, in this order from upstream, a three-way catalyst, an adsorbent-catalyst containing at least zeolite in its composition and capable of absorbing hydrocarbons, an electrically heated catalyst containing at least platinum in its composition, and a catalyst containing at least palladium in its composition. The electrically heated catalyst can effectively purify low boiling-point HC of paraffinic hydrocarbon which has been desorbed from the adsorbent-catalyst after about 20 seconds from the start of the engine. On the other hand, the catalyst can effectively purify high boiling-point HC of aromatic hydrocarbon which has been desorbed from the adsorbent-catalyst after about 80 seconds from the start of the engine. When the catalyst is an electrically heated catalyst, it is energized after the energization of the other electrically heated catalyst is ended and the supply of electric power can hence be minimized.

Abstract: A heat-insulating, light and vibration-proof exhaust manifold for a multi-cylinder internal combustion engine is provided. The exhaust manifold comprises an upper stream flange, a lower stream flange, four manifold pipes at an upper stream, a manifold chamber (gathering section) at a lower stream and a manifold case of a plate metal covering the manifold pipes and the manifold chamber. The manifold pipes have upper stream ends to be connected to exhaust ports of the internal combustion engine through the upper stream flange and lower stream ends gathering in the manifold chamber. Upper stream ends of the manifold pipes and the manifold case are welded to the upper stream flange, and lower stream ends of the manifold chamber and the manifold case are welded to the lower stream flange. The manifold pipe and the manifold chamber can slide relatively at a slide portion which is maintained by pressing the manifold chamber and the manifold case against the manifold pipe.