Dry sump crankcase

Claim 1

A dry sump type crankcase for an automotive type internal combustion engine having an intake manifold and a positive crankcase ventilation (PCV) system for automatically and continuously ventilating the crankcase, the system including an essentially atmospheric pressure fresh air inlet to the engine passing air therethrough to the crankcase and a connection from the oil pan to the vacuum in the intake manifold establishing a constant flow of crankcase vapors therebetween, the oil pan having a baffle therein partitioning it into an inner oil collecting funnel-like crankcase cavity and an outer oil reservoir, the inner cavity having an opening at its lowermost point for communication of oil with the reservoir, the opening being of a controlled vertical height for creating a pressure differential across the baffle during operation of the engine, and means connecting the inner cavity to the air inlet pressure side of the PCV System while connecting the reservoir to the vacuum side of the PCV system for establishing a constant pressure differential across the baffle sufficient to displace the oil against gravity and maintain the oil level in the crankcase during operation of the engine at the height of the opening in the baffle, gravity causing the oil to seek a level higher than the opening upon shutdown of the engine and the consequential decay of vacuum in the intake manifold.