Reduction of Parasitic Losses in Front-End-Accessory-Drive Systems - Part 1

Paper #:
  • 2017-01-0893

  • 2017-03-28
Demanding CO2 and fuel economy regulations are continuing to pressure the automotive industry into considering innovative powertrain and vehicle-level solutions. Powertrain engineers continue to minimize engine internal friction and transmission parasitic losses with the aim of reducing overall vehicle fuel consumption. Strip friction methods are used to determine and isolate components in engines and transmissions with the highest contribution to friction losses. However, there is relatively little focus on friction optimization of Front-End-Accessory-Drive (FEAD) components such as alternators and AC compressors. This paper will outline the development of a flexible test stand that allows for highly accurate torque measurements on such components under precisely controlled environmental boundary conditions and device loads. Component-specific parasitic loss evaluations are conducted through a direct-drive arrangement, while vehicle-specific installations are analyzed through a belt-driven system adhering to wrap angles and tension forces, as measured in the vehicle setup. This paper will discuss aspects of the test stand design that provide flexibility for adaptation to various test scenarios. The results from measurements for a number of FEAD components will be shown in the context of scatterbands derived from multiple component tests. Key results from direct-drive and belt-driven component tests will be utilized to illustrate the influence of the belt layout on mechanical efficiency of the FEAD system. The component-level results will also be discussed in the context of vehicle-level operating strategies (e.g., “smart” charging). Strategy adjustments and calibration for entire drive cycles and resulting fuel economy benefits will conclude the technical discussion in this paper.
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