Apparatus for recirculating exhaust gases

An apparatus for recirculating exhaust gases, comprising:

• exhaust gas recirculating passage means for providing communication between the intake and exhaust passages of an internal combustion engine, said passage means having the inlet end thereof communicating with said exhaust passage, and the outlet end of said passage means communicating with said intake passage at a location disposed downstream of the throttle plate;
• constriction means provided in said passage means;
• control valve means for controlling the recirculation of exhaust gases through said passage means, said control valve means including a movable control valve provided in said passage means downstream of said constriction means, said control valve means also including actuator means for controlling the movement of said control valve between opened and closed positions, said actuator means including a fluid pressure chamber having a movable actuator member associated therewith and interconnected to said control valve;
• a negative control pressure passage connected between a port in the intake passage and the fluid pressure chamber for introducing negative control pressure to the control valve means;
• pressure chamber means interposed between said constriction means and said control valve, said pressure chamber means having a pressure therein which is substantially equal to atmospheric pressure when the control valve is opened and to that in the exhaust passage when the control valve is closed;
• first operating valve means for opening said negative control pressure passage to the atmosphere when the pressure in said chamber means becomes substantially atmospheric and the rate of exhaust gas recirculation is substantially proportional to the rate of intake air flow;
• said first operating valve means including a movable valve element associated with a controlling chamber, a first controlling passage providing communication between said pressure chamber means and said controlling chamber, a second controlling passageway providing communication between the negative control pressure passage and the atmosphere, and said valve element when in a closed position closing off said second controlling passageway;
• and
• second operating valve means, responsive to the amount of sucked air flowing through the intake passage, for opening said negative control pressure passage to the atmosphere when the pressure in the intake passage exceeds a predetermined negative pressure level;
• said second operating valve means being independent of said first operating valve means and including a movable valve member associated with a control chamber, a first control passage communicating between said control chamber and said intake passage, and a second control passage providing communication between said negative control pressure passage and the atmosphere, said movable valve member coacting with said second control passage for controlling the flow therethrough.