System to feed exhaust gas into the intake manifold

Claim 1

An exhaust gas feed system for use with an internal combustion engine having a carburetor, a throttle valve rotatably disposed in an air-fuel mixture passage defined in said carburetor, an intake manifold for conveying the mixture to said engine, and an exhaust manifold for conveying the exhaust gases from said engine before discharging the same into the open air, said exhaust gas feed system comprising a first conduit fluidly connecting said exhaust manifold with said intake manifold for feeding a portion of exhaust gases in said exhaust manifold into said intake manifold; a restrictor disposed in said first conduit and having therein an opening operable to allow the exhaust gases passing therethrough to have a sonic velocity; valve means for varying the opening degree of said opening of said restrictor when actuated; pressure responsive means including a chamber fluidly connected through a second conduit with a port formed in said carburetor, and a movable member movable in response to vacuum supplied to said chamber, said port being located at a place where said port is positioned in the intake manifold side when the throttle valve is rotated at a predetermined angle from its closed position, said movable member carrying said valve means for actuating the same; a third conduit fluidly connecting said chamber of said pressure responsive means with the clean air side of an air filter; and magnetic valve means disposed in said third conduit and arranged to selectively close and open the passage of the same when electrically energized and de-energized.