| 摘要 |
PROBLEM TO BE SOLVED: To ensure excellent lubrication of a cam driving device even at a high rotating speed. SOLUTION: A cam driving device for an internal combustion engine of a manually operating work apparatus, particularly, a valve opening-closing system mixture method lubrication type internal combustion engine 1 having a cylinder 2, forming a combustion chamber 19 defined by a cylinder wall 22, a piston 18 and a cylinder head 3 in this cylinder, having a gas exchange valve 4 arranged in the cylinder head, having a valve stem 6 of this gas exchange valve driven by a valve timing device 8 via a rockable rocker arm 10, and having the valve timing device having a timing cam 15. The timing cam 15 is rotatably supported near the cylinder wall 22, a through hole 40 is formed in the cylinder wall, a first opening end part 41 of the through hole existe in a cylinder sliding surface 21 in a height position of a piston 18 existing in the lower dead center, and a second opening end part 42 of the through hole opens in a cam chamber 34 near the timing cam 15.
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