| 摘要 |
PURPOSE: A cam shaft structure is provided to achieve improved cooling performance of cylinder head, while reducing costs for manufacture of engine by eliminating the necessity of using an oil cooler and oil passage. CONSTITUTION: A cam shaft structure comprises oil flow increasing holes(14) formed at both sides of a cam bearing oil supply hole(13) in such a manner that the oil is supplied to both sides of a lower portion(31) of a cam bearing(30) where a small width portion is formed into a recess by the formation of a valve hole(22). The oil is directly supplied to a middle deck(21) of the cam bearing in case where the oil flow increasing holes pass through the small width portion during the rotation of a cam shaft(10). The oil is supplied to the inner surface of the cam bearing when the oil flow increasing holes pass through the position other than the small width portion.
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