Crankcase breather and lubrication oil system for an internal combustion engine.

摘要

An internal combustion engine (10) having a vertically oriented crankshaft (18) and a horizontally oriented cylinder bore (34) and including a plurality of lubrication sites to be pressure lubricated. A first upstanding wall (58) extends upwardly from the top wall (14) of the crankcase and circumscribes and defines a first chamber (60). A breather passage (64) communicates crankcase gases from the crankcase into the first chamber. A drain passage (70) communicates oil separated from the crankcase gases in the first chamber into the cylinder bore below the piston and is positioned along the cylinder bore so as to be periodically occluded by the piston during reciprocation thereof. A second upstanding wall (80) extends upwardly from the top wall of the crankcase in spaced relationship to at least a portion of the first wall, and defined together with the first wall a second chamber (86) therebetween. A first oil passage (90) communicates oil from a lubricant pump to the second chamber, and a second oil passage (92) communicates oil from the second chamber to at least one of the lubrication sites.