Diesel Powertrain Energy Management via thermal Management and Electrification 2017-01-0156
The coming Diesel powertrains will remain as key technology in Europe to achieve the stringent 2025 CO2 emission targets. Especially for applications which are unlikely to be powered by pure EV technology like Light Duty vehicles and C/D segment vehicles which require a long driving range this is the case. To cope with these low CO2 targets the amount of electrification e.g. in form of 48V Belt-driven integrated Starter Generator (BSG) systems will increase. On the other hand the efficiency of the Diesel engine will increase which will result in lower exhaust gas temperatures resulting in a challenge to keep the required NOx reduction system efficiencies under Real Drive Emissions (RDE) driving conditions. In order to comply with the RDE legislation down to -7 °C ambient an efficient thermal management is one potential approach.
Commonly utilized means to increase exhaust gas temperature are late injection and/or intake throttling, which enable sufficient NOx reduction efficiency. Additionally, increasing intake manifold temperature can also increase exhaust gas temperature, on top of stabilizing the combustion to reduce the emission of Hydro Carbons (HC) & Carbon Monoxides (CO). This can be achieved by using a new advanced Water Charge Air Cooler (WCAC) concept which enables, especially in cold ambient conditions, the control of temperature in the intake manifold up to the coolant temperature of main engine cooling circuit.
The potential of the combination of different thermal and electric systems has been studied within a RDE representative cycle. The target was to keep sufficient exhaust gas temperature supporting the NOx reduction system efficiency. Fundamentally these investigations have been focused on one cycle using a rule based approach. However the future variety of possible real drive scenarios will require other control concepts – the expected potential of future possibly predictive diesel BSG control concepts will be summarized.