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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.

An approach is presented here to analyze and quantify individual partial noise sources and their contribution to the overall pass-by SPL of a medium duty diesel truck. Navistar, Inc. and Pelzer Consult GmbH have developed and successfully verified this method on one of their current production International DuraStar model medium duty trucks. First the operational sound powers of all relevant noise sources were extracted with near field SPL measurements under real pass-by test run conditions. Second, the Spatial Transfer Path Analysis (TPA) from all individual noise sources to the receiver microphones under different view angles was measured. Finally each single contribution was calculated and summed up to the overall virtual pass-by SPL. This virtual SPL is in close agreement with the measured values. The output of such investigations was a near and far field sound power and contribution ranking which results in an improved accuracy applying sound treatments.

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.

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.