EXHAUST RECIRCULATION SYSTEM OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust recirculation system of an internal combustion engine which can secure desired NOx reduction effect even when an exhaust gas recirculation passage is clogged due to an increase in the amount of condensed water generated.

SOLUTION: The exhaust recirculation system of an internal combustion engine includes: a low pressure EGR system 17 containing a LPL-EGR pipe 71 and LPL-EGR valve 72; and an ECU 50 for feedback controlling opening of the LPL-EGR valve 72 on the basis of the detected pressure difference of a LP differential pressure sensor 107 for detecting the differential pressure on both end sides in an exhaust gas recirculation direction of the LPL-EGR pipe 71. The ECU 50 includes a clogging determination part 51 for determining whether or not the LPL-EGR pipe 71 is clogged or not, and a control condition setting part 52 for executing the feedback control based on the detected pressure difference of the LPL-EGR valve 72 when no clogging occurs in the LPL-EGR pipe 71 and changing the control based on the detected differential pressure into other control than the feedback control when the clogging is determined.

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