Super-Turbocharging the Gasoline Engine 2018-28-0007
In this paper, the concept of super-turbocharging is applied, in simulation, to a four-cylinder direct injection jet ignition gasoline engine. Turbocharging improves the power density of internal combustion engines, both the compression ignition and the spark ignition. However, a standalone turbocharger suffers from transient and steady state performance and efficiency degradation where the energy to turbine is either smaller or larger than what would be needed to optimize the engine operation in a specific point. Hence a concept is proposed to use a super-turbocharger, where the turbocharger shaft is connected to the crankshaft through a continuously variable transmission (CVT) and a gears pair. Energy is drawn from the crankshaft or delivered to the crankshaft to better work in every operating point. The concept was originally proposed for a diesel engine. Here it is applied to a gasoline engine. Results of simulations of engine performance are presented and discussed, prompting a conclusion that super-turbocharging would be suitable solution for gasoline engines, in terms of energy recovery, efficiency, boosting performance at low speed, and reducing the turbo lag.