METHOD OF CONTROLLING EXHAUST GAS RECIRCULATION IN TURBOCHARGED COMPRESSION-IGNITION ENGINE SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide exhaust gas recirculation control for compliance with exhaust gas regulations and for optimizing engine fuel economy and performance.

SOLUTION: The method of controlling exhaust gas recirculation (EGR) in a turbocharged compression-ignition engine system (10)including: the engine (12); an induction subsystem (14) in upstream communication with the engine; an exhaust subsystem (16) in downstream communication with the engine; a high pressure EGR path (46) between the exhaust and induction subsystems upstream of a turbocharger turbine (38) and downstream of a turbocharger compressor (28); and a low pressure EGR path (48) between the exhaust and induction subsystems downstream of the turbocharger turbine and upstream of the turbocharger compressor (28). A target total EGR fraction for compliance with exhaust emissions criteria is determined, and then a target HP/LP EGR ratio is determined to optimize other engine system criteria within the constraints of the determined target total EGR fraction.

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