EXHAUST GAS RECIRCULATION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

摘要

An exhaust gas recirculation system for an internal combustion engine includes an exhaust gas recirculation passage for communicating an exhaust port with an intake passage through a recirculation flow control valve. The recirculation system according to the invention comprises a timing valve in the recirculation passage adapted to open at specified moments for extracting exhaust gases containing highly concentrated hydrocarbons, According to the invention, moreover, the exhaust port is concentrically divided into a plurality of ports to extract exhaust gases having high concentrations of hydrocarbons from the outermost divided port adjacent to the inner peripheral walls of the exhaust port to recirculate them into intake mixtures, thereby reducing the concentrations of hydrocarbons and nitrogen oxides in exhaust gases and thus fuel comsumption.