| 摘要 |
PURPOSE:To improve the durability of the catalyst while securing its exhaust gas purifying performance. CONSTITUTION:A catalyst 16 for low and medium load and a catalyst 17 for high load are provided to the branch pipes 14 and 15 branched from the midway of an exhaust pipe 12, a switching valve 18 is furnished at the branching part of the branch pipes 14 and 15, the switching of the valves 18 is controlled by an ECU 19, hence the exhaust gas is passed through the catalyst 16 in the low and medium-load operation and through the catalyst 17 in high-load operation. The amt. of the catalystic component deposited on the catalyst 17 is increased on the upstream side and minimized close to the end face on the downstream side to lower the maximum temp. in the catalyst, and the total deposition amt. of the entire catalyst component is reduced as compared with the catalyst 16. Meanwhile, the amt. of the catalystic component deposited on the catalyst 16 is increased at the upstream and downstream parts and minimized close to the center to make the temp. distribution in the catalyst practically uniform in the low and medium-load operation. |
