ENGINE CRANKCASE VENTILATION SYSTEM INCLUDING A BLOWBY GAS PASSAGE DEFINED BETWEEN CRANKCASE MEMBERS

摘要

In an engine crankcase ventilation system, a blowby gas passage (25) and a fresh air passage (26) are defined between adjoining crankcase members so as to extend in parallel with a crankshaft axial line along either side of a lower part of said crankcase assembly. Because the crankcase is configured to receive the rotating crankshaft (7) provided with counterweights, it necessarily has a circular cross section. Therefore, this arrangement allows effective utilization of the available space. Thus, a cavity of a required volume for effective oil separation and pressure pulsation damping can be formed in the engine main body without increasing the number of components parts, and without complicating or increasing the size of the overall structure.