Efficient Combination of Electric Supercharger, Cooled EGR and 12V Extended Stop Start for Future Boosted Gasoline Engines

On turbo gasoline applications, direct injection is positively coupled to camphasers to improve low end torque and transient response of the turbocharger. Based on its significant CO2 benefits when associated to downsizing and downspeeding, this architecture has become the major worldwide trend to improve gasoline engine fuel consumption. Nevertheless coming stringent regulations on CO2 emissions, pollutant emissions especially in real life (RDE) require new improvements.
In this paper, a new architecture is presented in order to address the next generation of low CO2 turbo GDI engines. It relies on the combination and coupling optimization of three technologies: electric supercharger, 12V extended stop start network and low pressure EGR. Based on already demonstrated electric supercharger dynamic performance, architecture optimization will be explained both on air side through compressor wheel analysis and on electrical side. Advances on 12V electrical network allowing extended stop start function as well as regenerative braking and boost support through electric supercharger will be explained. Electric supercharger and low pressure gasoline EGR combination also offers new levers of engine improvement especially at mid and high loads. Focus will be given on optimization of air and EGR loops, durability results and combination perspectives.