| 摘要 |
PROBLEM TO BE SOLVED: To compatibly secure cooling properties of a part around a combustion chamber and a part around an exhaust manifold in a cylinder head having the exhaust manifold formed as one unit. SOLUTION: A rough surface structure 10 including fine air holes is worked on one of inner wall surfaces in a combustion chamber side jacket part 8 and an exhaust manifold side jacket part 9, and another of the inner wall surfaces is left as casting surface. In one jacket part in which the rough surface structure 10 is worked on the inner wall surface, nuclear boiling is promoted by accelerating formation of babbles by air holes of the rough surface structure 10 and cooling is mainly done by heat transfer of nuclear boiling. Cooling is done by forced convection heat transfer in another jacket part in which the inner wall surface is left as casting surface. Consequently, cooling properties at the exhaust manifold 2 and the combustion chamber 4 are compatibly secured with low cooling water flow rate as compared to cooling done by only forced convection heat transfer. COPYRIGHT: (C)2011,JPO&INPIT
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