Exhaust gas recirculating system

In an internal combustion engine having an intake system with a throttle valve and an exhaust system,

• an exhaust gas recirculating system comprising:
• an EGR duct connecting the exhaust gases passing through the exhaust system to the intake system;
• an EGR valve normally closing said EGR duct to prevent recirculation and movable by a signal vacuum applied thereto to an open position;
• control means operable to provide a signal vacuum to said EGR valve including a vacuum line connecting a vacuum port communicating with the intake system above the idle speed position of the throttle valve to said EGR valve;
• air bleed means including a vent in said vacuum line;
• and flow restricting means in said vacuum line fluidly intermediate said vacuum port and vent;
• said air bleed means including an air bleed control valve movable into and out of said vent to close or open the same;
• first means biasing said air bleed valve closed;
• servo means connected to said air bleed control valve for moving it to an open vent position in response to vacuum in said vacuum line intermediate said flow restricting means and EGR valve;
• second means for biasing said servo means in response to the engine manifold vacuum in a direction to move said air bleed control valve to an open vent position;
• and third means for biasing said second biasing means to vary movement of said air bleed control valve to an open vent position.