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.
Highlights
Energy consumption reduction is an important target for the automotive industry, given the progressive introduction of stringent CO2 emission regulations [1]
The results show the importance importance of the power loss contributions purely related to the wet clutches, namely of the power loss contributions purely related to the wet clutches, namely Pc,wc + Pms,ewc + P,cc,wc
The paper discussed the relative significance of the individual power loss contributions of a seven-speed dual clutch transmission system with wet clutches, designed for high performance vehicle applications
Summary
Energy consumption reduction is an important target for the automotive industry, given the progressive introduction of stringent CO2 emission regulations [1]. Significant progress has been made, e.g., through the development of downsized engines [2], engine start-and-stop functions [3] and electrified or fully electric drivetrain layouts [4,5,6,7]. Important fuel consumption reductions can be achieved through the implementation of energy-efficient transmission layouts, which are the focus of this study. Transmission systems with automated gearshifts have become a customer requirement for driving comfort in premium passenger cars. Conventional automatic transmissions (ATs) have lower efficiency than manual transmissions (MTs), mainly because of the viscous shear losses in the torque converter.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
