Electric Turbo Assist as an Enabler for Engine Downspeeding

Electric Turbo Assist (ETA) is a novel air system technology that provides an extra degree of freedom in engine-turbocharger matching for optimal system performance and emissions. This paper presents simulation results from a research project to develop and demonstrate ETA, an integrated turbocharger-motor/generator, for a particular off-road machine duty cycle. Engine cycle simulation tools have been employed to investigate the potential of ETA to reduce fuel consumption through a combined downspeeding and exhaust energy regeneration strategy while meeting the required emissions levels and maintaining the desired engine response. Results show that ETA enables a flexible air system that can meet and even exceed the required air-fuel ratio and exhaust gas recirculation targets when the engine is downspeeded, while providing a useful fuel saving over the non-ETA baseline engine calibration.