Turbocharging Technologies to Meet Critical Performance Demands of Ultra-Low Emissions Diesel Engines 2004-01-1359
Over the past decade, the dramatic improvements in power density, responsiveness and low emissions in both turbo-diesel passenger vehicle and commercial vehicle engines have demanded significant alterations to the basic architecture of turbochargers. The emissions regulations already enacted worldwide, but not yet in force will demand further reaching changes to the basic concept of turbocharging. This paper explores the complex linkage between the aerodynamic machine (the turbocharger), the positive displacement machine (the engine), their new role as feed-gas generators for aftertreatment devices, and the divergence in requirements between passenger vehicle and commercial vehicle applications.
The next generation requirements (2007) for both passenger vehicle and commercial vehicle diesel engines will be driven by the need for increased EGR rates. The following generation requirements (2010) will be driven by the unique demands of Lean NOx Adsorbers or Selective Catalytic Reduction systems.
Due to the different emissions tests and market drivers, the critical-to-quality requirements will be different for the PV and CV segments. The 2007 regulations will drive turbocharger architectures for CV engines that can operate at pressure ratios 4.5/1 and higher, and can mitigate the negative fuel economy impact of high levels of EGR. These regulations will drive turbocharger architectures for PV engines that can provide increased responsiveness, particularly off-idle.