Exhaust gas recirculation system of engine

摘要

An exhaust gas recirculation control device of an engine is provided. The device includes: an exhaust turbocharger having a turbine disposed in an exhaust passage and a compressor disposed in an intake passage; an intercooler disposed in the intake passage downstream of the compressor; a low-pressure EGR passage connecting the exhaust passage downstream of the turbine to the intake passage upstream of the compressor; a low-pressure EGR valve disposed in the low-pressure EGR passage and for changing a cross-sectional area thereof; a high-pressure EGR passage connecting the exhaust passage upstream of the turbine to the intake passage downstream of the intercooler; a high-pressure EGR valve disposed in the high-pressure EGR passage and for changing a cross-sectional area thereof; a valve control device for controlling openings of the low-pressure and high-pressure EGR valves; and a gear range detector for detecting a gear range of a transmission.

主权项

1. A turbocharged internal combustion engine having an exhaust gas recirculation (EGR) control system of an engine, the control system comprising:
an exhaust turbocharger having a turbine disposed in an exhaust passage of the engine and a compressor disposed in an intake passage; an intercooler disposed in a part of the intake passage downstream of the compressor; a low-pressure EGR passage connecting a part of the exhaust passage downstream of the turbine to a part of the intake passage upstream of the compressor; a low-pressure EGR valve disposed in the low-pressure EGR passage and for changing a cross-sectional area of the low-pressure EGR passage; a high-pressure EGR passage connecting a part of the exhaust passage upstream of the turbine to a part of the intake passage downstream of the intercooler; a high-pressure EGR valve disposed in the high-pressure EGR passage and for changing a cross-sectional area of the high-pressure EGR passage; a valve controller that adjusts openings of the low-pressure EGR valve and the high-pressure EGR valve, the valve controller being operatively coupled to the low-pressure EGR valve and the high-pressure EGR valve; and a gear range detector for detecting a gear range of a transmission of a vehicle in which the engine is installed;
wherein the valve controller is configured to calculate a non-travel range ratio and a travel range ratio that is lower than the non-travel range ratio, the travel and non-travel range ratios being ratios of an amount of exhaust gas recirculated by the high-pressure EGR passage to a total amount of exhaust gas recirculated by the low-pressure EGR passage and the high-pressure EGR passage combined;wherein when the gear range detected by the gear range detector is a travel range, the valve controller adjusts the openings of the low-pressure EGR valve and the high-pressure EGR valve so that a ratio of an amount of exhaust gas recirculated by the high-pressure EGR passage to a total amount of exhaust gas recirculated by the low-pressure EGR passage and the high-pressure EGR passage combined becomes the travel range ratio; andwherein when the engine is in an idle operation and the gear range detected by the gear range detector is a non-travel range, the valve controller adjusts the openings of the low-pressure EGR valve and the high-pressure EGR valve so that a ratio of an amount of exhaust gas recirculated by the high-pressure EGR passage to a total amount of exhaust gas recirculated by the low-pressure EGR passage and the high-pressure EGR passage combined becomes the non-travel range ratio.