Cooled Exhaust Gas Recirculation on Boosted SI-Engines - An invehicle Technology Evaluation

摘要

Downsizing and Downspeeding in combination with turbocharging are known and established technologies to reduce CO2 emissions and state of the art technology to run the engine in areas of high engine efficiency. The demand for high Low-End-Torque (LET) and, simultaneously, low fuel consumption in areas of high engine power output requires compromises with respect to compression ratio and turbocharger sizing. This limits the achievable fuel consumption benefits. Cooled exhaust gas recirculation is a promising technology to realize further fuel consumption benefits in wide engine map areas of turbocharged gasoline engines. Cooled external EGR on boosted gasoline engines has been investigated using a demo vehicle in this paper. As a first step, possible EGR system variants has been selected based on dyno results. The chosen system then has been integrated in an Opel Insignia. Besides gaining experience regarding vehicle integration, focus lays on evaluating the technology under real world conditions. Results regarding fuel consumption, stoichiometric engine operation potential and drivability are main goals in the investigation. Finally, challenges associated with cooled external EGR and the technology potential are summarized and evaluated.