| 摘要 |
<p>PROBLEM TO BE SOLVED: To raise an emission control function while securing catalyst converter heat resistance, by forming a bypass passage on an exhaust passage so as to detour an upstream catalyst converter and providing a radiation means for facilitating heat release from exhaust gases flowing through the bypass passage to the cooling air introduced to an engine room. SOLUTION: An upstream catalyst converter casing 23 is laid behind an exhaust manifold 10, and a downstream catalyst converter is connected to the outlet of the upstream catalyst converter casing 23 via an exhaust pipe 29. In this case, the upstream catalyst converter casing 23 is positioned under a dashboard 31, and a heat releasing wall 28 for forming a bypass passage 4 to detour an upstream catalyst converter 2 is integrated with the upstream catalyst converter casing 23. This bypass passage 4 opposes the flow of the cooling air, thereby securing a large area of the heat radiating wall 28 which the cooling air touches and enhancing heat releasability to the cooling air from exhaust gases flowing in the bypass passage 4.</p> |
