Abstract
Keywords Downsizing, Electric Supercharging, Series Turbocharging, Boost Control, Diesel Engine
Abstract - An electrical on-demand supercharger provides an internal combustion engine with the facility to increase its low speed torque output, without being subject to the mechanical, thermal and fluid-dynamic constraints associated with conventional exhaust-driven pressure charging devices. The Visteon Torque Enhancement System (VTES) is a fully integrated air management system, at the heart of which is a highly responsive electronically controlled, electrically powered supercharger. When combined with a conventional turbocharger the system allows aggressive engine downsizing whilst maintaining the important driveability characteristics of low speed torque output and transient response akin to larger, naturally aspirated engines. Alternatively, it has been proposed that highly downsized engines can achieve similar performance benefits with a 2-stage turbocharging system. This is where a small turbocharger is used in series with a larger device to improve the gas flow matching between engine and boosting system, thus enabling increased torque at low speed and enhanced transient response.
In this paper, a highly downsized diesel engine is presented and its simulated performance is compared when using the electrical supercharging and 2-stage turbocharging systems. The relative merits of both systems are discussed and points relating to the application and control of both systems are raised.