Exhaust gas recirculation control system

摘要

An exhaust gas recirculation control system for an internal combustion engine for removing nitrogen oxides (NOx) in exhaust gases comprises a positive pressure delay valve in a negative pressure passage for introducing intake negative pressure in the proximity of a throttle valve of a carburetor into an exhaust gas recirculation control valve to maintain the negative pressure therein during an acceleration, thereby effecting the exhaust gas recirculation even when accelerating to purify the nitrogen oxides in the exhaust gas. The exhaust gas recirculation control system further comprises a positive pressure delay valve in an advance negative pressure passage for introducing the intake negative pressure in the vicinity of the throttle valve of a carburetor into a distributor and synchronized with the above positive pressure delay valve to maintain the distributor advanced, thereby keeping a good combustion of fuel mixture.