| 摘要 |
PURPOSE:To efficiently cool a wall surface of a combustion chamber at a knocking point part, by connecting cooling water passages below ports in series with a cooling water passage above the combustion chamber, and permitting a cooling water to flow from the former to the latter to thereby supply a sufficient flow rate of cooling water to a port area. CONSTITUTION:There are independently provided in a cylinder head 2 a lower cooling water passage 13 extending below suction ports 6 and 7 along a row of cylinders, a lower cooling water passage 14 extending below exhaust ports 8 along the row of cylinders, and an upper cooling water passage 15 extending along the row of cylinders in such a manner as to pass through a central portion of a combustion chamber 5 between the suction ports 6 and 7 and the exhaust ports 8 and surround an ignition plug hole. The cylinder head 2 is further provided with a communication hole 17 for supplying a cooling water from a cooling water passage in a cylinder block to an end portion 13a of the lower cooling water passage 13. The water cooling water passages 13, 15 and 14 are connected in series with each other in this order. |
