| 摘要 |
PROBLEM TO BE SOLVED: To provide an oil return passage structure of a cylinder head having an integrally formed collective exhaust port in a multicylinder engine, by increasing a degree of freedom of design of wall parts 88, 90, 92, 94 and 96 for turning exhaust gas from an exhaust port 74 of a plurality of combustion chambers to a collective exhaust port 76, for improving cooling performance to respective oil return passage 98 and boss hole 86 of a cylinder head fastening bolt. SOLUTION: This oil return passage structure has first wall parts 88 and 90 in a shape of joining on the collective exhaust port 76 side by extending from the combustion chamber side on both sides by partitioning mutual adjacent combustion chambers, and second wall pats 92, 94 and 96 formed in a shape of joining on the collective exhaust port 76 side by extending from respective exhaust ports by partitioning a pair of mutual exhaust ports of the respective combustion chambers. The boss hole 86 for the cylinder fastening bolt for joining a cylinder head 70 to a cylinder block 68, is arranged in a position separate from the first wall parts 88 and 90, and the oil return passage 98 is arranged on the collective exhaust port 76 side in the second wall parts 92, 94 and 96. COPYRIGHT: (C)2011,JPO&INPIT
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