Patent ID: 7857883

Claim:
An inertial air-oil separator for removing oil mist droplets in blowby gas from an internal combustion engine, comprising an inlet for receiving said blowby gas from the engine, and an outlet discharging separated air, an acceleration nozzle accelerating said blowby gas therethrough along an axial flow direction from upstream to downstream, an inertial impactor collector in said housing downstream of said acceleration nozzle in the path of said accelerated blowby gas and causing oil droplet separation from said blowby gas, said acceleration nozzle comprising an upstream entrance axial end receiving said blowby gas from said inlet, a downstream exit axial end discharging said blowby gas against said inertial impactor collector, and a flexible sidewall extending axially between said entrance axial end and said exit axial end and guiding said blowby gas therealong, said flexible sidewall flexing radially inwardly and outwardly to decreasingly and increasingly, respectively, vary the flow to said inertial impactor collector responsive to the pressure of said blowby gas from said engine and pressure drop across said acceleration nozzle, and providing increased separation efficiency early in the life of the engine without suffering objectionably high pressure drop late in the life of the engine including end-of-life condition of the engine, by said flexible sidewall flexing radially outwardly to increase acceleration nozzle orifice area in response to increasing blowby gas flow and pressure as the engine ages, wherein said flexible sidewall flexes such that pressure drop across said acceleration nozzle is a nonquadratic function of flowrate therethrough and such that pressure drop changes as a more linear function of said flowrate as compared to a quadratic function in a plot of pressure drop vs. flowrate, with increasing flowrate occurring with increasing age of the engine as piston rings wear and blowby gas flow increases, wherein the flexing of said flexible sidewall provides a more linear, flatter slope in said plot than a quadratic function.