Patent ID: 8056544
Filing Date: 2011-11-15
Classification: F02M

Abstract:
1. A method for operating an internal combustion engine Exhaust Gas Recirculation (EGR) system, such system having: a processor; an air intake to the engine; an exhaust gas recirculation (EGR) path for directing a portion of exhaust gas produced by the engine into the air intake; such exhaust gas recirculation path comprising: an EGR cooler for cooling the exhaust gas as such exhaust gas passes through the EGR path to the air intake; an EGR valve operative in response to an EGR valve position signal produced by the processor for controlling the amount of the exhaust gas fed to the EGR cooler, the method comprising: producing the EGR valve position signal in accordance with a difference between actual engine exhaust NOx and a preset NOx level when such processor determines the EGR cooler efficiency is less than the predetermined level, such produced the EGR valve position signal being operated to decrease the amount of exhaust gas passed to the EGR cooler when such processor determines EGR cooler efficiency is less than the predetermined level; wherein the engine includes: an EGR coolant supply for providing a coolant to the EGR cooler; and a EGR coolant valve operative in response to an EGR coolant valve position signal produced by the processor for controlling the amount of the coolant fed to the EGR cooler, and including: producing the EGR coolant valve position signal in accordance with a difference between actual EGR cooler gas outlet temperature and a preset EGR cooler gas outlet temperature, such produced EGR coolant valve position signal being operated to decrease the amount of coolant passed to the EGR cooler when such processor determines the EGR cooler efficiency is less than the predetermined level.