| 摘要 |
PURPOSE:To make the durability improvement of a lean NOx catalyst and reduction of HC emission compatible. CONSTITUTION:An exhaust purifying device for an internal combustion engine 2 consists of the internal combustion engine 2, ternary catalyst 6 installed in an exhaust system 4, and a bypass passage 12 for leading the exhaust on the upstream side of the ternary catalyst into a lean NOx catalyst 8, making a detour around the ternary catalyst 8. Since the lean NOx catalyst 8 can be arranged in the low temperature part on the downstream side of the exhaust system, the thermal deterioration can be prevented, and further, since the ternary catalyst 6 can be arranged in the high temperature part on the upstream side of the ternary catalyst 6, the HC emission can be effectively reduced. Even if the ternary catalyst 8 exists on the upstream side of the lean NOx catalyst 8, exhaust is allowed to flow into the lean NOx catalyst 8, making a detour around the ternary catalyst 6, the HC shortage can be prevented. Accordingly, the durability improvement of the lean NOx catalyst 8 can be made compatible with the HC emission. |
