EGR SYSTEM FOR INTERNAL COMBUSTION ENGINE AND METHOD FOR CONTROLLING THE SAME

摘要

An EGR system includes a high-pressure EGR passage (41) that provides communication between an exhaust pipe, at a portion upstream of a turbine (5b) of a turbo charger (5), and an intake pipe (3), at a portion downstream of a compressor (5a), a low-pressure EGR passage (31) that provides communication between the exhaust pipe (4), at a portion downstream of the turbine (5b), and the intake passage (3), at a portion upstream of the compressor (5a), and an exhaust gas catalyst (10) provided upstream of a position at which the low-pressure EGR passage (3) is connected to the exhaust pipe (4). When an internal combustion engine (1) is in the transitional state from the low-load operating state to the high-load operating state (S303), if incomplete combustion is detected in the internal combustion engine (S304) and the bed temperature of the exhaust gas catalyst (10) is lower than the reference temperature (S305), the high-pressure EGR gas amount is made larger than the prescribed high-pressure EGR gas amount determined based on the operating state of the internal combustion engine (S306). Thus, an excessive decrease in the intake air temperature is suppressed, and therefore occurrence of incomplete combustion is suppressed.