On the Energy Efficiency of Dual Clutch Transmissions and Automated Manual Transmissions

Fabio Vacca, Stefano De Pinto, Ahu Ece Hartavi Karci, Patrick Gruber, Fabio Viotto, Carlo Cavallino, Jacopo Rossi and Aldo Sorniotti
Additional contact information
Fabio Vacca: Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH, UK
Stefano De Pinto: Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH, UK
Ahu Ece Hartavi Karci: Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH, UK
Patrick Gruber: Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH, UK
Fabio Viotto: Oerlikon Graziano S.p.A., 10098 Rivoli, Italy
Carlo Cavallino: Oerlikon Graziano S.p.A., 10098 Rivoli, Italy
Jacopo Rossi: Oerlikon Graziano S.p.A., 10098 Rivoli, Italy
Aldo Sorniotti: Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH, UK

Energies, 2017, vol. 10, issue 10, 1-22

Abstract: The main benefits of dual clutch transmissions (DCTs) are: (i) a higher energy efficiency than automatic transmission systems with torque converters; and (ii) the capability to fill the torque gap during gear shifts to allow seamless longitudinal acceleration profiles. Therefore, DCTs are viable alternatives to automated manual transmissions (AMTs). For vehicles equipped with engines that can generate considerable torque, large clutch-slip energy losses occur during power-on gear shifts and, as a result, DCTs need wet clutches for effective heat dissipation. This requirement substantially reduces DCT efficiency because of the churning and ancillary power dissipations associated with the wet clutch pack. To the knowledge of the authors, this study is the first to analyse the detailed power loss contributions of a DCT with wet clutches, and their relative significance along a set of driving cycles. Based on these results, a novel hybridised AMT (HAMT) with a single dry clutch and an electric motor is proposed for the same vehicle. The HAMT architecture combines the high mechanical efficiency typical of AMTs with a single dry clutch, with the torque-fill capability and operational flexibility allowed by the electric motor. The measured efficiency maps of a case study DCT and HAMT are compared. This is then complemented by the analysis of the respective fuel consumption along the driving cycles, which is simulated with an experimentally validated vehicle model. In its internal combustion engine mode, the HAMT reduces fuel consumption by >9% with respect to the DCT.

Keywords: dual clutch transmissions; hybridised automated manual transmissions; power loss contributions; experiments; driving cycle simulations (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2017
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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