| 摘要 |
PURPOSE:To sufficiently lubricate an intake valve, a discharge valve, a cylinder and so on by shaping an oil sump and a passage in a cylinder wall and also shaping an oil sump groove in a piston. CONSTITUTION:When a pinton 6 reaches a point adjacent to the lower dead point center, the oil sump 6a of a the piston 6 and the passage 5a of the cylinder 5 come to relatively opposing positions. Oil in the oil sump 5a of the cylinder 5 then flows from the passage 5b of the cylinder into the oil sum 6a of the piston 6. In such state, oil flows through the oil passage 6b of the piston 6 as shown by an arrow A and is stuck to an intake valve, a discharge valve, the piston 6 and the cylinder 5. The lubricating characteristics can therefore be maintained sufficiently.
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