Patent ID: 7431023
Filing Date: 2008-10-07
Classification: F01M

Abstract:
1. A positive crankcase ventilation system for an internal combustion engine, the system comprising: an engine having a cylinder air intake system connected to associated cylinders and a filtered air inlet to a crankcase for admitting air to mix with crankcase vapors; a throttle disposed in the cylinder air intake system for controlling cylinder intake airflow to the associated cylinders; and a venturi nozzle having a throat spaced between an inlet and an outlet at opposite ends; the venturi nozzle inlet being connected to the crankcase for receiving the mixture of filtered air and crankcase vapors, and the venturi nozzle outlet being connected to the cylinder air intake system at a location subject to variable intake vacuum pressures between the throttle and the cylinders to allow the mixture of filtered air and crankcase vapors to be drawn into the inlet air passing to the cylinders downstream of the throttle; wherein the venturi nozzle is sized to provide generally constant sonic velocity flow of the mixture of filtered air and crankcase vapors under engine operating conditions when the throttle is at least partially closed and a substantial intake vacuum is present.