| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent condensed water from being brought into contact with a catalyst in an exhaust passage not used when the exhaust passage is switched to regulate a contact temperature. <P>SOLUTION: A loop-like exhaust tube 9b is connected to the exhaust passage 3 on an upstream side of an NOX storage catalyst 7 disposed in the exhaust passage of an internal combustion engine, and a switching valve 9c is provided at a connector. A normal exhaust passage for introducing the exhaust gas from the upstream side exhaust passage to the catalyst via a direct inlet exhaust passage 9a, and a cooling exhaust passage for introducing the exhaust gas from the upstream side exhaust passage via the loop exhaust tube 9b and from the inlet exhaust passage to the catalyst, are formed. Thus, the normal exhaust passage and the cooling exhaust passage are switched by using the switching valve to regulate the catalyst temperature. The outer wall of the inlet A, the outlet B and the opposite side C of the loop exhaust tube is connected by welding or the like to the part of the downstream side exhaust passage 11 of the catalyst, and a heat is transferred to the wall surface of the loop exhaust tube to form the connector 13 as a heating means for maintaining the wall surface temperature high to prevent the moisture from being condensed. <P>COPYRIGHT: (C)2004,JPO |
