| 摘要 |
A cylinder head 32 of an internal-combustion engine 30 has: a combustion chamber 32a; and an intake port 37i and an exhaust port 37e that open into the combustion chamber. An oil groove 32f is formed on the outer surface of a top part wall 32b of the combustion chamber 32a of the cylinder head 32. A cover plate 9 covers the oil groove such that an oil passage 95 is formed. A cam shaft holder 7 rotatably supports a cam shaft 81 of a valve train 8. In such a structure, the cam shaft holder 7 is formed separately from the cylinder head 32; the cover plate 9 is interposed between the cam shaft holder 7 and the cylinder head 32; and the cover plate 9, the cam shaft holder 7, and the cylinder head 32 are fastened together by a fastening bolt 91 that fixes the cam shaft holder 7 to the cylinder head. As a result, it is possible to obtain an oil passage structure for a cylinder head such that a bolt fixing only the cover plate is unnecessary, the number of components can be reduced, the surface area of the cover plate can be increased, and the degree of freedom in the layout of the oil passage is increased. |
