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Heavy-duty diesel engines face increasingly stringent emissions regulations. The trade-off between fuel economy and NOx emissions and between NOx and particulate emissions is becoming even more critical. In the light of these regulations and the trade-off among many variables, air handling and exhaust gas recirculation (EGR) systems become increasingly important. Three advanced turbocharging technologies - variable nozzle turbochargers, integral EGR pump and an ultra-high pressure ratio, long life compressor are described. In this paper an overview of the designs and their impact on fuel economy, low speed torque, emissions and durability is described. It is shown that significant improvements in all four variables are readily possible with the use of these advanced turbocharging technologies. It is shown that variable nozzle (VNT) turbocharging reduces smoke particularly at low speeds by a factor of 5, improves torque at low engine speeds and improves fuel economy by about 3%.

Diesel engines face increasingly stringent emissions regulations worldwide. The trade-off between fuel economy and NOx emissions and between NOx and particulate emissions is becoming more critical. In light of these regulations and design trade-offs among many variables, engine-boosting systems have become increasingly important. An advanced variable nozzle turbocharger (AVNT™) is described. The innovative design is described along with key characteristics. The design features a minimization of additional parts associated with the variable geometry mechanism and electro-hydraulic actuation integrated with the bearing system. The impact of variable geometry turbocharging on diesel engine performance, fuel economy, torque, emissions and braking capability is described. It is shown that significant improvements in all five variables are readily possible with the use of this variable geometry turbocharger.