| 摘要 |
PURPOSE:To improve the warming-up performance at the time of starting an engine and cooling performance of an exhaust manifold by setting the injection rate of the inner surface and the outer surface of a heat insulator which covers the outer surface of the exhaust manifold greater than that of the outer surface of the exhaust manifold. CONSTITUTION:The heat insulation and cooling of an exhaust manifold 4 are carried out by utilizing radiant heat transfer between the exhaust manifold 4 and a heat insulator 5. The outer surface 4a of the exhaust manifold 4 is a metallic oxidized surface, and the injection ratio epsilon1 of the outer surface 4a is almost 0.75. The heat insulator 5 whose inner surface 5a and outer surface 5b ar metallic glossy surfaces, where the injection rate is almost 0.1. By applying a black heat resistant coating 6 to the inner surface and the outer surface 5b of the heat insulator 5, the injection rates epsilon2, epsilon3 of the inner surface and the outer surface of the heat insulator 5 are set larger than the injection rate epsilon1 of the outer surface 4a of the exhaust manifold 4. It is thus possible to improve the warming-up performance and cooling performance. |
