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Development of a Low Loss Clutch for CVT Reverse Function
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 02, 2019 by SAE International in United States
This content contains downloadable datasetsAnnotation ability available
Continuously variable transmissions (CVT) provide superior fuel economy by enabling internal combustion engines to operate at their “sweet spots”. However, there is still potential to improve CVT system’s mechanical efficiency, and further enhance vehicle-level fuel economy. In the past, extensive research work has focused on the core continuously variator unit (CVU) that includes pulleys and a belt or chain. Another thread of research has centered on optimization of CVT clamping force control to reduce hydraulic system loss. Nonetheless, to the best of our knowledge, very little research has looked into the planetary gear sets and clutches that enable the CVT system to switch between forward, neutral and reverse gears. The state-of-the-art reverse clutch usually consists of multiple friction and steel plates, and is normally open during all forward driving maneuvers. The relative speed between friction and steel plates is identical to turbine speed, which generate spin loss. We believe there is an opportunity to improve the CVT system mechanical efficiency by replacing the reverse plate clutch with a low loss clutch, for example a binary clutch. At first, we studied the theoretical spin loss associated with plate clutches. Secondly, we identified the most challenging shifting maneuver using the lever diagram analogy. Thirdly, we proposed a control strategy to address the most critical rolling garage drive-to-reverse shift, and conducted one-dimensional simulation using an AMESim model to validate our strategy by comparing our simulation result with available vehicle data. At last, we obtained spin loss data from dynamometer testing to evaluate the potential fuel economy benefit.
CitationDuan, C., Lee, C., Yao, J., Samie, F. et al., "Development of a Low Loss Clutch for CVT Reverse Function," SAE Technical Paper 2019-01-0774, 2019, https://doi.org/10.4271/2019-01-0774.
Data Sets - Support Documents
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- Iwasawa , T. Development of a New Variator System for Jatco CVT7 W/R 5th International CTI Symposium Shanghai, China Sep. 2016
- Teubert , A. , Englisch , A. , Götz , A. , Linnenbrügge A. et al. 2009
- Ando , T. , Yagasaki , T. , Ichijo , S. , Sakagami , K. et al. Improvement of Transmission Efficiency in CVT Shifting Mechanism Using Metal Pushing V-Belt SAE Int. J. Engines 8 3 1391 1397 2015 10.4271/2015-01-1103
- Kitabayashi , H. , Chen , Y. , and Henry , H. Analysis of the Various Factors Affecting Drag Torque in Multiple-Plate Wet Clutches SAE Technical Paper 2003-01-1973 2003 10.4271/2003-01-1973
- Pahlovy , S. , Mahmud , S. , Kubota , M. , Ogawa , M. et al. Multiphase Drag Modeling for Prediction of the Drag Torque Characteristics in Disengaged Wet Clutches SAE Int. J. Commer. Veh. 7 2 2014 10.4271/2014-01-2333
- Pahlovy , S. , Mahmud , S. , Kubota , M. , Ogawa , M. et al. New Development of a Gas Cavitation Model for Evaluation of Drag Torque Characteristics in Disengaged Wet Clutches SAE Int. J. Engines 9 3 2016 10.4271/2016-01-1137
- Yuan , Y. , Liu , E. , Hill , J. , and Zou , Q. An Improved Hydrodynamic Model for Open Wet Transmission Clutches Journal of Fluids Engineering 129 3 333 337 2007
- Duan , C. Analytical Study of a Dog Clutch in Automatic Transmission Application SAE Int. J. Passeng. Cars-Mech. Syst 7 3 1155 1162 2014 10.4271/2014-01-1775