| 摘要 |
PURPOSE:To equalize temperature of the internal peripheral wall of each intake port and prevent the generation of a thermal distortion, by differently forming an opening area of communication holes connecting a cooling water passage in a cylinder block with a cooling water passage in a cylinder head formed in the vicinity of the two intake ports. CONSTITUTION:An inflow of intake air to the second intake port 2B is heated to a high temperature by pressurizing the intake air to increase its temperature in a high speed and high load range when an opening and closing valve 3 opens, on the contrary an inflow of intake air to the first intake port 2A decreases its temperature with heat being absorbed by vaporizing injection fuel from a fuel injection valve 5, simultaneously a wall of the first intake port 2A also decreases its temperature. Here an opening area of the first communication hole 16A is set smaller than the opening area of the second communication hole 16B. Accordingly, an engine, decreasing an inflow quantity of cooling water to a cooling water passage 15 in a cylinder head side through the first communication hole 16A from a cooling water passage 12 in a cylinder block side smaller as compared with an inflow quantity of cooling water to a part in the vicinity of an external wall of the second intake port 2B through the second communication hole 16B, enables the desired end to be attained. |
