| 摘要 |
PROBLEM TO BE SOLVED: To provide structure for avoiding stress concentration caused around a bolt hole in a circumference of an end of a bolt in a fastened part and to make a crankcase lightweight, in an internal combustion engine provided with the fastening bolt for fastening upper and lower crankcases in a circumference of a crankshaft and the bolt hole which is formed in the crankcase and into which the fastening bolt is inserted and tightened. SOLUTION: An opening is formed at an upper end of the bolt hole in the upper crankcase, the end of the bolt hole is made to communicate with the opening, and the end of the fastening bolt is protruded into the opening in fitting the bolt. COPYRIGHT: (C)2008,JPO&INPIT
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