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

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Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH, UK
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McLaren Automotive Ltd, Woking GU21 4YH, UK
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Oerlikon Graziano S.p.A., 10098 Rivoli, Italy
*
Author to whom correspondence should be addressed.
Energies 2017, 10(10), 1562; https://doi.org/10.3390/en10101562
Received: 29 July 2017 / Revised: 4 September 2017 / Accepted: 14 September 2017 / Published: 11 October 2017
(This article belongs to the Section Electrical Power and Energy System)
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. View Full-Text
Keywords: dual clutch transmissions; hybridised automated manual transmissions; power loss contributions; experiments; driving cycle simulations dual clutch transmissions; hybridised automated manual transmissions; power loss contributions; experiments; driving cycle simulations
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Vacca, F.; De Pinto, S.; Hartavi Karci, A.E.; Gruber, P.; Viotto, F.; Cavallino, C.; Rossi, J.; Sorniotti, A. On the Energy Efficiency of Dual Clutch Transmissions and Automated Manual Transmissions. Energies 2017, 10, 1562.

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