Exhaust gas recirculation system with control apparatus for exhaust gas flow control valve

Claim 1

An exhaust gas recirculation system for use on an internal combustion engine having an intake system and an exhaust system comprising: a recirculation conduit to recirculate a portion of exhaust gas from the exhaust system of an internal combustion engine to an intake system having a carburetor and an intake manifold; an exhaust gas flow control valve normally closing said recirculation conduit; a valve actuator including a vacuum chamber and a diaphragm operatively connected to said exhaust gas flow control valve to urge said exhaust gas flow control valve toward its open position so as to open said recirculation conduit responsive to a vacuum in the vacuum chamber of said valve actuator; and a control apparatus comprising: a housing having a vacuum regulating chamber, said vacuum regulating chamber having an inlet port connected to the vacuum chamber of said valve actuator, an air bleed port and an outlet port connected in operation to a vacuum source; a first flexible diaphragm means defining a wall of said vacuum regulating chamber; a second flexible diaphragm means cooperating with said first flexible diaphragm means for defining said housing and between said first and second diaphragm means a biasing chamber, said second flexible diaphragm means forming on the opposite side of a side exposed to said biasing chamber and in said housing a venturi vacuum chamber communicating with the venturi of the carburetor; means mechanically interconnecting said first and second flexible diaphragm means; said first diaphragm means having a valve portion engageable with said outlet port, said first diaphragm means being movable in increase and decrease of pressure in said vacuum regulating chamber to bring said valve portion into out of closing engagement with said outlet port; said second diaphragm means having an effective area larger than that of said first diaphragm means; an air bleeder valve means for opening said air bleed port in response to further flexing of said first diaphragm means due to increase of vacuum in said vacuum regulating chamber after closing of said outlet port; a vacuum conduit having an air bleeder orifice, said vacuum conduit connecting said biasing chamber with the intake manifold, and said air bleeder orifice having a restriction chosen such that a vacuum in said biasing chamber is a reduction of a vacuum in the intake manifold and is lower than a vacuum in said venturi vacuum chamber.