| 摘要 |
A vertical internal combustion engine E has a crankshaft 18 enclosed in a crank chamber 20 , a belt-drive transmission mechanism 50 held in a belt chamber 63 and including a rubber belt 53 for transmitting power of the crankshaft 18 to a camshaft 24 in a valve train 23, and a transmission case 60 defining the belt chamber 63 . The belt chamber 63 communicates with the crank chamber 20 by way of vent holes 70 and 71 , the transmission case 60 is provided with an internal wall W<SUB>i </SUB>disposed between the vent holes 70 and 71 and the belt 53 in the belt chamber 63 to deflect the flow of an oil-containing gas flowing from the crank chamber 20 into the belt chamber 63 such that the oil-containing gas flows in directions deviating from a direction toward the belt 53 . The belt 53 is lubricated with oil in the oil-containing gas. The belt 53 is pre-vented from being excessively exposed to the oil-containing gas from the crank chamber 20 to extend its life.
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