Internal combustion engine with crankcase ventilation system

摘要

An internal combustion engine is equipped with a crankcase ventilation system in which fresh air flows through a crankcase. The cylinder block of the engine is formed with a fresh air suction port whose one end is opened to the chamber of a crankcase in order to establish communication between a rocker cover chamber and the crankcase chamber. The one end of the fresh air suction port is located in the vicinity of the peripheral surface of a counterweight of a crankshaft. The rotation of the counterweight develops vacuum thereby to suck fresh air from the rocker cover chamber through the fresh air suction port into the crankcase chamber, thereby effecting ventilation in the crankcase.