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The small-displacement direct-injection (DI) diesel engine is a prime candidate for future transportation needs because of its high thermal efficiency combined with near term production feasibility. Ford Motor Company and FEV Engine Technology, Inc. are working together with the US Department of Energy to develop a small displacement DI diesel engine that meets the key challenges of emissions, NVH, and power density. The targets for the engine are to meet ULEV emission standards while maintaining a best fuel consumption of 200g/kW-hr. The NVH performance goal is transparency with state-of-the-art, four-cylinder gasoline vehicles. Advanced features are required to meet the ambitious targets for this engine. Small-bore combustion systems enable the downsizing of the engine required for high fuel economy with the NVH advantages a four- cylinder has over a three-cylinder engine.

An overview description of candidate energy converters being considered for application in the Partnership for a New Generation of Vehicles (PNGV) program is presented. These energy converters include compression-ignition, direct-injection (CIDI) engines, gas turbine turbogenerators (T/G), and Stirling-cycle machines. Chrysler Corporation is investigating the CIDI engine for use in a parallel hybrid electric vehicle (HEV), Ford is investigating T/Gs, and General Motors is developing a Stirling-cycle generator for use in a series HEV. A summary of ongoing work for each of these technologies is provided, including current project status and future plans. An overview of current PNGV specifications for highly efficient energy converters is also included.

A generic simulation study examines the fuel economy interrelationship between basic engine design parameters and the choice of transmission, emphasizing the implications on engine design of the use of optimally shifted, advanced transmissions. A new engine model and a vehicle simulation package were combined to assess, with both conventional and optimal shifting, the fuel economy effects, without octane or emissions constraints, of variation in bore-to-stroke ratio, compression ratio, cam timing, displacement, and friction level. The fuel economy interaction between the engine technology and the type of transmission was also assessed, using measured fuel flow information on a series of diesel and PROCO engines. In the course of this work, the fundamental factors which determine the fuel economy improvement associated with optimal shifting were identified.

Experimental measurements of burn rates have been carried out in a single cylinder homogeneous charge engine. Three different combustion chambers were investigated (75 % and 60 % squish bowl-in-piston chambers and a disk chamber) using a cylinder head with a swirl producing intake port and near central spark location. Data were obtained with each combustion chamber as a function of spark timing, EGR, and load at 1500 RPM. The combustion rate is strongly influenced by chamber shape. The 10-90 % burn durations of the 75 % and 60 % squish chambers are respectively about 40 % and 60 % that of the disk chamber. Chamber configuration had less effect on 0-10 % burn duration. The disk had about 25 % longer 0-10 % burn time than the bowl-in-piston chambers. Modifications to the GESIM model enabled good overall agreement between predictions and experimental data, a rather severe test of the model because the coupling of fluid mechanics, combustion and chamber geometry must be properly modeled.