Exhaust gas purification system of internal combustion engine

Abstract

An exhaust gas purification system of an internal combustion engine having a bypass exhaust gas passage, openable through a switch-over valve, branched from an exhaust pipe at a location downstream of a catalytic converter and again merged into the exhaust pipe at a downstream point, an adsorbent installed in the bypass exhaust gas passage which adsorbs unburned component of the exhaust gas, and an EGR pipe which recirculates the exhaust gas including the unburned components at a location upstream of the catalytic converter, wherein the EGR pipe is made of metal such as stainless steel and is connected to the bypass exhaust gas passage such that the recirculation pipe is brought into thermal contact with the exhaust pipe, thereby enabling to effectively prevent blocking or corrosion of the EGR pipe or switch-over valve from occurring. The inner wall of the recirculation pipe is formed with liquid repellent and oil repellent film so as to overcome moisture-related problems more effectively.