Engine crankcase ventilation

Claim 2

The combination with an internal combustion engine having a crankcase and a combustion air inlet of engine shutdown means connected to the engine crankcase and responsive to a predetermined positive pressure therein to stop the engine, crankcase ventilation means communicating said crankcase with said air inlet for drawing crankcase vapors into the combustion air stream, orifice means in said communicating means and providing a fixed restriction to fluid flow therethrough, and regulating valve means in said communicating means downstream of said orifice means, said valve means providing a variable restriction to fluid flow and being operative to limit the negative control pressures Upstream thereof to a predetermined value regardless of greater negative pressures in the air inlet, said control pressure limit being chosen and said orifice means being sized to permit passage of a sufficient flow of crankcase vapors during normal engine operation to maintain a predetermined maximum vacuum in the engine crankcase but to provide a sufficient flow restriction to cause development of positive pressure in the crankcase sufficient to actuate said shutdown means to stop the engine when there occurs an abnormally high flow of blowby into the crankcase indicative of engine malfunction.

Claim 3

A crankcase ventilation system in combination with an internal combustion engine having a combustion air inlet, a crankcase and engine shutdown means connected with said crankcase and adapted to be actuated by a predetermined positive pressure therein to terminate engine operation, said crankcase ventilation means comprising means communicating said crankcase with said air inlet for drawing a flow of crankcase vapors into the combustion air stream, regulating valve means in said communicating means and providing a variable restriction to fluid flow therethrough, said valve means being responsive to system pressures upstream thereof to vary said restriction in a manner to maintain a predetermined maximum vacuum upstream thereof, and fixed orifice means in said communicating means between said regulating valve means and said crankcase, said orifice means being sized to restrict fluid flow sufficiently to cause development of a positive pressure in the crankcase to actuate said shutdown means under predetermined conditions of excess engine blowby but to allow the passage of sufficient ventilation flow to permit the establishment of a predetermined maximum crankcase vacuum under normal engine operating conditions.

Claim 4

A crankcase ventilation system in combination with an internal combustion engine having a combustion air inlet, a crankcase and engine shutdown means connected with said crankcase and adapted to be actuated by a predetermined positive pressure therein to terminate engine operation, said crankcase ventilation means comprising means communicating said crankcase with said air inlet for drawing a flow of crankcase vapors into the combustion air stream, regulating valve means in said communicating means and providing a variable restriction to fluid flow therethrough, said valve means being responsive to system pressures upstream thereof to vary said restriction in a manner to maintain a predetermined maximum vacuum upstream thereof, and fixed orifice means in said communicating means between said regulating valve means and said crankcase, said orifice means being sized to restrict fluid flow sufficiently to cause development of a positive pressure in the crankcase to actuate said shutdown means under predetermined conditions of excess engine blowby but to allow the passage of sufficient ventilation flow to permit the establishment of a predetermined maximum crankcase vacuum under normal engine operating conditions.

Claim 5

The combination of claim 2 and further including an oil separator in said communicating means, upstream of said orifice means, said oil separator being adapted to separate and return to the engine crankcase excess oil passing into the ventilation system with the crankcase vapors.

Claim 6

An internal combustion engine having in combination an exhaust-driven turbocharger operable to supply varying amounts of combustion air to the engine under various engine operating conditions, a combustion air inlet to the turbocharger subject to substantial variations in sub-ambient air pressure under the varying air flows drawn into said turbocharger, an enclosed crankcase into which engine blowby gases are received in varying amounts during engine operation, pressure responsive means connected with said crankcase and responsive to a predetermined, positive pressure therein to stop said engine, crankcase ventilation means communicating said crankcase with said air inlet for drawing crankcase vapors into the combustion air stream, a regulating valve in said communicating means and providing a variable restriction to fluid flow therethrough, said valve being operable to vary said restriction so as to limit the vacuum immediately upstream thereof to a predetermined maximum, and a fixed orifice in said communicating means between said regulating valve and said crankcase and sized to permit a sufficient flow of crankcase vapors through said communicating means to establish a substantial crankcase vacuum under normal engine operating conditions but to restrict flow sufficiently to cause development of a positive pressure in the crankcase sufficient to actuate said pressure responsive means under predetermined conditions to excess engine blowby.

Claim 7

An internal combustion engine having in combination an exhaust-driven turbocharger operable to supply varying amounts of combustion air to the engine under various engine operating conditions, a combustion air inlet to the turbocharger subject to substantial variations in sub-ambient air pressure under the varying air flows drawn into said turbocharger, an enclosed crankcase into which engine blowby gases are received in varying amounts during engine operation, pressure responsive means connected with said crankcase and responsive to a predetermined, positive pressure therein to stop said engine, crankcase ventilation means communicating said crankcase with said air inlet for drawing crankcase vapors into the combustion air stream, a regulating valve in said communicating means and providing a variable restriction to fluid flow therethrough, said valve being operable to vary said restriction so as to limit the vacuum immediately upstream thereof to a predetermined maximum, and a fixed orifice in said communicating means between said regulating valve and said crankcase and sized to permit a sufficient flow of crankcase vapors through said communicating means to establish a substantial crankcase vacuum under normal engine operating conditions but to restrict flow sufficiently to cause development of a positive pressure in the crankcase sufficient to actuate said pressure responsive means under predetermined conditions to excess engine blowby.