Valuation rings and rigid elements in fields

A control system for use in an exhaust gas recirculation system of an internal combustion engine, in which part of exhaust gases is recirculated from an exhaust system to an intake system in an attempt to reduce the amount of harmful components contained in exhaust gases from the engine as well as to prevent lowering of the running performance of the engine, by controlling the aforesaid recirculation system. This control system includes: a recirculation control valve which controls a recirculation joint portion between the exhaust system and the intake system; a fuel control mechanism which increases the open, cross sectional area of a fuel metering member in a carburetor for compensating for the lowered running performance of the engine due to the exhaust gas recirculation; and a negative-pressure switching valve which selectively supplies an intake negative pressure to the recirculation control valve as well as to the control input end of the fuel control mechanism.