Technologies that provide potential for significant improvements in engine efficiency include, engine downsizing/downspeeding (enabled by advanced boosting systems such as an electrically driven compressor), waste heat recovery through turbocompounding or organic Rankine cycle and 48 V mild hybridization. FEV’s Integrated Turbocompounding/Waste Heat Recovery (WHR), Electrification and Supercharging (FEV-ITES) is a novel approach for integration of these technologies in a single unit. This approach provides a reduced cost, reduced space claim and an increase in engine efficiency, when compared to the independent integration of each of these technologies.
This approach is enabled through the application of a planetary gear system. Specifically, a secondary compressor is connected to the ring gear, a turbocompounding turbine or organic Rankine cycle (ORC) expander is connected to the sun gear, and an electric motor/generator is connected to the carrier gear. The planetary gear system is equipped with a dry clutch and a band brake allowing flexibility in mechanical and electrical integration of the turbocompound turbine, secondary compressor and electric motor/generator to the engine. The system provides the ability to do electrical integration of turbocompound turbine/ORC expander when the turbine power output is low and mechanical/power-split integration when the turbine power output is high. At low engine speeds and high loads, the secondary compressor can provide power from the turbocompound turbine or from the electric motor. Furthermore, the electric motor/generator can be used for regenerative braking as well as to provide torque assist to the engine when possible.
The 1D simulation tool GT-Power was used to evaluate the performance of this planetary gear enabled approach against an approach that integrates each of these technologies (a turbocompound turbine, a 48 V belt starter generator and a 48 V e-compressor) independently on a downsized four cylinder diesel engine applied in a medium heavy-duty class 6/7 vocational vehicle. The fuel consumption of both approaches was compared over the engine map and over engine certification test cycles. The simulations demonstrated the ability of the planetary gear coupled system to match the engine performance of the baseline 7.7 L 6 cylinder engine while providing an additional fuel consumption benefit when compared to independent integration of these technologies. Finally, a 3D CAD model of the planetary gear coupled system was developed and the space claim was compared against the baseline 6 cylinder engine.