Smog control device for internal combustion engine

Claim 1

In an internal combustion engine which creates a suction head during operation and having a passage for introducing air into the engine, said passage having an inlet thereto, a throttle valve in said passage movable from an open to a closed position, a crankcase, and wherein imperfect fuel combustion results in the accumulation of blow-by gases in the crankcase, the improvement comprising: a first conduit communicating the crankcase with the passage, said first conduit having an outlet in direct communication with the passage at a point above the throttle valve for drawing gases from the crankcase in response to the flow of air through said passage; a second conduit communicating the crankcase with the passage at a point below the throttle valve for drawing gases from the crankcase in response to the suction head of the engine when the throttle valve has been moved to a position restricting the flow of air through the passage; and a third conduit communicating the crankcase with said passage, said third conduit having an inlet in indirect and restricted communication with said passage to cause a pressure differential between the passage inlet and the third conduit inlet whenever air flowing through the passage causes a negative pressure in the passage, whereby the flow of gases from the crankcase through either of said first and second conduits results in a compensating flow of air through said third conduit into the crankcase to preclude vacuum or pressure buildup therewithin and the flow of air into said third conduit is opposed by the flow of air into said passage.