Auxiliary pollution control device for spark-ignition engines

In an internal combustion engine system having means to reduce the emission of toxic pollutants, the system comprising:

• a carburetor for feeding an intimate mixture of liquid fuel and air to the engine and having a principal throttle valve therein;
• an intake manifold in fluid flow connection with the carburetor, downstream of the principal throttle valve, and with the engine;
• an exhaust manifold in fluid flow connection with the engine;
• an exhaust-recirculation conduit in fluid flow connection with the exhaust manifold and with the intake manifold;
• and a second throttle valve in the recirculation conduit mechanically interconnected to the principal throttle valve, whereby the degree of opening of the second valve is governed by the degree of opening of the principal valve;
• the improvement comprising a distributor in fluid flow connection between the recirculation conduit and the intake manifold, the distributor being disposed about at least a major portion of the periphery of the intake manifold along at least a portion of the length thereof;
• and a continuous slit orifice of uniform width defined through the peripheral wall of the intake manifold and providing the only fluid flow connection between the distributor and the intake manifold, the slit extending around at least a major portion of the periphery of the intake manifold, whereby exhaust gases directed into said distributor flow through said continuous slit orifice of uniform width and are accelerated close to sonic speeds and injected into said intake manifold substantially uniformly about said least a portion of the periphery of said intake manifold to thereby substantially improve mixing of fuel and air within said intake manifold and reduce the amount of pollutants released by the internal combustion engine.