Driving Cycle Based Control and Calibration for a Turbocharged SI Engine with Low Pressure EGR System

Low pressure cooled EGR (LPEGR) for spark ignition (SI) engines is known to be one of the key technologies to benefit fuel consumption owing to lower pumping loss at part load, knock suppression capability and extended stoichiometric operating range thanks to combustion cooling effect. In order to implement this technology to industrialised application with the optimal performance efficiently and robustly, several challenges need to be solved, especially the EGR estimation accuracy and transport delay estimation accuracy during transient. And these challenges could be more complex on a turbocharged SI engine due to the much longer induction system, and more complex air path model due to the introduction of turbine, compressor and dump valve.

This paper describes the control and calibration method for a turbocharged LPEGR engine, and the validation result in Worldwide harmonized Light vehicles Test Cycles (WLTC). The test result shows remarkable fuel benefit and accurate EGR estimation. Furthermore, the control architecture, Engine Management System (EMS) co-operation method, control performance and real-world application issues will be also discussed. The introduced LPEGR engine control and calibration development method shows great efficiency and flexibility, which allows Ricardo to offer the same off-the-shelf service to customers.