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Selective Catalytic Reduction (SCR) systems provide excellent NOX control for diesel engines provided the exhaust aftertreatment inlet temperature remains at 200° C or higher. Since diesel engines run lean, extended light load operation typically causes exhaust temperatures to fall below 200° C and SCR conversion efficiency diminishes. Heated urea dosing systems are being developed to allow dosing below 190° C. However, catalyst face plugging remains a concern. Close coupled SCR systems and lower temperature formulation of SCR systems are also being developed, which add additional expense. Current strategies of post fuel injection and retarded injection timing increases fuel consumption. One viable keep-warm strategy examined in this paper is cylinder deactivation (CDA) which can increase exhaust temperature and reduce fuel consumption.

The development of commercial vehicles demand a rigorous and relatively expedient integration and validation to be performed in order to have the vehicle delivered to a satisfied customer. In today's market, the end customer often request for vehicles with various customizations and requirements for vocational performance, such as load and fuel economy. These requirements often run into conflict with vehicle dynamics fundamentals such as ride and handling. Examples of such concern are vocation bodies that do not have weight distributed unevenly or even ones that bias the static load distribution of the vehicle such that ride and handling are affected because of change in bounce, roll and pitch natural frequencies. One tool that can be used to develop and evaluate vehicle response to provide guidance for production vehicles is multibody dynamics. Unlike the passenger car industry, no two trucks rolling down the assembly line are necessarily the same.

Architecting and integrating commercial hybrid electric vehicles (HEV) is a long and labor intensive process which is unique every time. The challenge intensifies when one attempts to create an HEV capable of engine-off operation. Presenter Benjamin Saltsman, Eaton Corp.

This paper is the third part of a series of three papers (parts) that address diesel engine applications. It provides an overview on the differences in emissions, operation, and design characteristics between eight categories of various diesel engine applications that engine system design engineers need to know, including on-road heavy-duty, on-road light-duty, land-based mobile off-road, locomotive, marine, stationary, alternative fuels and biodiesel, and two-stroke diesel engines. The analysis technique of competitive benchmarking mapping is introduced by using a large amount of production engine application data to reveal design trends. Two empirical formulae are developed for the relationship between engine performance and design parameters. A summary table of engine system design considerations and priorities for different applications is developed as a design guideline.

A key strategy to improving the real-world fuel consumption and emissions of medium and heavy duty vehicles is the hybridization of these applications. Unlike the passenger vehicle market, medium and heavy duty applications are typically comprised of a range of components from a variety of manufacturers. The vocational market diversity and size places considerable demand on fuel efficiency and emission compliance. Medium and heavy duty applications have the ability to be successfully hybridized in ways that are not currently, or would not be practical within a passenger vehicle. This would also drive greater truck and bus vertical integration of the hybrid components. However, medium and heavy duty manufacturers have been prevented from certifying a full vehicle level platform due to the current engine only certification requirements.