Exhaust gas recirculation system

Claim 1

In combination with an internal combustion engine having a throttle valve controlled induction passage for conducting an air-fuel mixture into the engine for combustion therein and an exhaust means for the discharge of exhaust gases from the engine, the exhaust means including exhaust passage means and a catalytic converter connected to the exhaust passage means at the downstream end thereof, of a bypass duct connected at one end to said exhaust passage means upstream of said catalytic converter and at its opposite end to said intake passage downstream of said throttle valve, a bypass valve pivotally mounted in said bypass duct for movement therein between a closed position and a full open position and, temperature responsive means positioned in thermal relation with said catalytic converter and operatively connected to said bypass valve for effecting movement of said bypass valve between said closed position and said full open position, movement of said bypass valve from said closed position toward said open position occurring at a predetermined temperature in said catalytic converter as sensed by said temperature responsive means, the opening of said valve being proportional to further increases in temperature in said catalytic converter above said predetermined temperature up to a second predetermined temperature at which said bypass valve is in said full open position.