Michael Weissbäck

The tailored powertrain for 48 V – options for the gasoline engine – chance for future Diesel engines

The next steps of fuel consumption legislation will require a combination of engine measures with various electrification measures, dependent on the vehicle segment, to reduce the energy demand targets of the vehicle. The introduction of 48V electrical architecture provides increased electric recuperation and limited electric driving at lower cost compared to full hybrid solutions, offering considerable fuel reduction potential in the WLTC.

The Efficiency Engine – Cost-Effec tive Alternative to Downsizing

COMBUSTION ENGINES, No. 2/2012 (149) 1. Reduced friction and fuel consumption Reduction of fuel consumption and costs dominate the future market requirements in drive train development. Alongside electrification, downsizing concepts currently play a major role in CO2 reduction. However, this route means a further cost increase for the diesel engine in order to offer acceptable performance in heavy vehicles using engines with reduced displacement. Main cost drivers are the modified fuel injection and boosting-system for increased specific power density as well as the higher efficiency requirement for the NOx aftertreatment system. An attractive alternative to a classical downsizing concept is an efficiency-engine concept, optimized for a more moderate power density and minimized frictional losses. In this case, instead of reducing swept volume, the specific power density is reduced to 45 kW/l in the first generation, thus covering the needs of the high volume market. For this moderate power density the required peak firing pressure is reduced to a value even lower than those of some turbocharged gasoline engines. With a consequent modular redefinition of the crank train the friction can be significantly reduced, achieving a CO2 reduction corresponding to a swept volume reduction by 20 to 25%. In this paper the details of such an efficiency engine concept (DDE: Derated Diesel Engine) will be discussed in comparison to a typical downsizing concept (ADD: Aggressive Downsized Diesel) [1].