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Modeling the Effects of Transmission Gear Count, Ratio Progression, and Final Drive Ratio on Fuel Economy and Performance Using ALPHA
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 05, 2016 by SAE International in United States
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The Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) tool was created by EPA to evaluate the Greenhouse Gas (GHG) emissions of Light-Duty (LD) vehicles . ALPHA is a physics-based, forward-looking, full vehicle computer simulation capable of analyzing various vehicle types combined with different powertrain technologies. The software tool is a MATLAB/Simulink based desktop application. The ALPHA model has been updated from the previous version to include more realistic vehicle behavior and now includes internal auditing of all energy flows in the model . As a result of the model refinements and in preparation for the mid-term evaluation (MTE) of the 2022-2025 LD GHG emissions standards, the model is being revalidated with newly acquired vehicle data.
This paper presents an analysis of the effects of varying the absolute and relative gear ratios of a given transmission on carbon emissions and performance. Energy-based methods of selecting absolute gear ratios are considered and the effects of alternative engine selections are also examined. An algorithm is presented for automatically determining ALPHAshift parameter sets based on the selected engine and transmission combination. It is observed that no single ratio progression optimizes fuel consumption for all applications, however, fuel consumption is also relatively insensitive to progression which implies a fixed set of ratios can still be used for a range of applications without necessarily compromising consumption. The energy-based ratio analysis may prove useful in determining the optimal overall top gear ratio for a given engine-vehicle combination and also helps to explain the relative insensitivity to ratio progression. Individual performance metrics can show high sensitivity to ratio progression, final drive ratio and shift calibration, in particular 30-50 and 50-70 MPH passing times.
CitationNewman, K. and Dekraker, P., "Modeling the Effects of Transmission Gear Count, Ratio Progression, and Final Drive Ratio on Fuel Economy and Performance Using ALPHA," SAE Technical Paper 2016-01-1143, 2016, https://doi.org/10.4271/2016-01-1143.
- Lee , B. , Lee , S. , Cherry , J. , Neam , A. et al. Development of Advanced Light-Duty Powertrain and Hybrid Analysis Tool SAE Technical Paper 2013-01-0808 2013 10.4271/2013-01-0808
- Newman , K. , Dekraker , P. , Zhang , H. , Sanchez , J. et al. Development of Greenhouse Gas Emissions Model (GEM) for Heavy- and Medium-Duty Vehicle Compliance SAE Int. J. Commer. Veh. 8 2 2015 10.4271/2015-01-2771
- US EPA, DOT/NHTSA Final Rulemaking to Establish Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards, Joint Technical Support Document http://www.epa.gov/otaq/climate/regulations/420r10901.pdf Aug. 2012
- Malliaris , A. , Withjack , E. , and Gould , H. Simulated Sensitivities of Auto Fuel Economy, Performance and Emissions SAE Technical Paper 760157 1976 10.4271/760157
- US EPA Computer Simulation of Light-Duty Vehicle Technologies for Greenhouse Gas Emission Reduction in the 2020-2025 Timeframe http://www3.epa.gov/otaq/climate/documents/420r11020.pdf 2011
- Robinette , D. A DFSS Approach to Determine Automatic Transmission Gearing Content for Powertrain-Vehicle System Integration SAE Int. J. Passeng. Cars - Mech. Syst. 7 3 1138 1154 2014 10.4271/2014-01-1774
- Robinette , D. and Wehrwein , D. Automatic Transmission Gear Ratio Optimization and Monte Carlo Simulation of Fuel Consumption with Parasitic Loss Uncertainty SAE Int. J. Commer. Veh. 8 1 45 62 2015 10.4271/2015-01-1145
- Lemazurier , L. , Shidore , N. , Kim , N. , Moawad , A. et al. Impact of Advanced Engine and Powertrain Technologies on Engine Operation and Fuel Consumption for Future Vehicles SAE Technical Paper 2015-01-0978 2015 10.4271/2015-01-0978
- Newman , K. , Kargul , J. , and Barba , D. Development and Testing of an Automatic Transmission Shift Schedule Algorithm for Vehicle Simulation SAE Int. J. Engines 8 3 2015 10.4271/2015-01-1142
- Newman , K. , Doorlag , M. , Barba , D. EPA ALPHA Modeling of a Conventional Mid-Size Car with CVT and Comparable Powertrain Technologies SAE Technical Paper 2016-01-1141 2016
- Naunheimer H. et al. Automotive Transmissions - Fundamentals, Selection, Design and Applications Springer Berlin Heidelberg 978-3-642-16213-8 10.1007/978-3-642-16214-5 2011
- Newman , K. , Kargul , J. , and Barba , D. Benchmarking and Modeling of a Conventional Mid-Size Car Using ALPHA SAE Technical Paper 2015-01-1140 2015 10.4271/2015-01-1140
- Scherer , H. , Bek , M. , and Kilian , S. ZF New 8-speed Automatic Transmission 8HP70 - Basic Design and Hybridization- SAE Int. J. Engines 2 1 314 326 2009 10.4271/2009-01-0510
- US EPA, DOT/NHTSA Joint Technical Support Document: Final Rulemaking for 2017-2025 Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards http://www3.epa.gov/otaq/climate/documents/420r12901.pdf 2012
- Kargul , J. , Moskalik , A. , Barba , D. , Newman , K. et al. Estimating GHG Reduction from Combinations of Current Best-Available and Future Powertrain and Vehicle Technologies for a Midsized Car Using EPA’s ALPHA Model SAE Technical Paper 2016-01-0910 2016
- Lee , S. , Schenk , C. , McDonald , J. Air Flow Optimization and Calibration in High-compression-ratio Naturally Aspirated SI engines with Cooled-EGR SAE Technical Paper 2016-01-0565 2016