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Getting Power to the Pavement
Published in Patrick Hossay, Automotive Innovation, 2019
Even though automation is impressive, in itself it does not solve one of the fundamental challenges of manual transmissions: the time required to shift gears. Any gear shift has to entail four steps: a disengagement of the clutch, a move out of one gear ratio, a move into another gear ratio, and clutch reengagement. That takes time, even if done automatically. The result is an undesirable torque interruption. But, as always, there is another option: This challenge can be met by the integration of two clutches, a dual-clutch transmission (DCT) (Image 3.11). If we use two clutches, the disengagement of one gear and the engagement of another don’t have to happen sequentially, and that means a faster transition. Originally branded by Volkswagen as the Direct Shift Gearbox (DSG) and Audi as the S-Tronic transmission, versions of dual-clutch units are provided by just about every major automaker.
Semi-automatic and automatic transmissions
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
For the enthusiastic driver who demands a responsive car with competitive acceleration times, the Volkswagen Group in conjunction with BorgWarner introduced in 2003 what is termed their Direct Shift Gearbox, usually abbreviated to ‘DSG’. It is claimed to be able to change gear faster and more smoothly than conventional manual and automatic gearboxes, without incurring any loss of performance or fuel economy since it does not require a torque converter. This type of gearbox was first used in an Audi rally car in the mid-1980s, but it had to await the development of reliable electronic controls before its more recent application to production models. In principle the gearbox may be classified as a ‘dual-clutch’ transmission, which in this case features a divided input primary shaft flanked by two output mainshafts that connect to the final-drive gear and differential.
Automotive Transmissions and Drive Trains
Published in Don M. Pirro, Martin Webster, Ekkehard Daschner, Lubrication Fundamentals, 2017
Don M. Pirro, Martin Webster, Ekkehard Daschner
Dual clutch transmission (DCT) is another form of electronically shifted manual transmission that is an alternative to an automatic transmission. DCT can be considered as two manual transmissions in one housing. This arrangement uses two clutches for even and odd gearsets. Computers, solenoids, and hydraulics do the shifting instead of a clutch pedal, making it an automated manual transmission. Improved fuel economy and smooth shifting are some of the claims coming from proponents of DCT designs. The use of these DCTs in some passenger cars is growing globally from its initial European application.
Multi-objective optimization of gearshift trajectory planning for multi-speed electric vehicles
Published in Engineering Optimization, 2022
Kegang Zhao, Ziqi Li, Yuzhong Chen, Yanwei Liu
The use of electric vehicles (EVs) is an effective way to alleviate environmental and energy problems (Shin, Jung, and Oh 2017; Li et al.2018; Li, Khajepour, and Song 2019). EVs are typically equipped with single-speed transmissions, but these can hardly meet the increasing performance demand for EVs. Research shows that the application of multi-speed transmissions can effectively reduce energy consumption and considerably improve launching and acceleration performance (Urbina Coronado, Castañón, and Ahuett-Garza 2018; Liu et al.2020). For example, Sorniotti et al. (2011) demonstrated the potential advantages of a two-speed transmission for power performance and energy consumption. Among the various multi-speed transmissions, the dual-clutch transmission (DCT) has advantages such as high transmission efficiency and uninterrupted torque transfer (Walker, Zhang, and Tamba 2011; Berkel et al.2014). Thus, research on multi-speed transmissions for EVs has garnered substantial interest, and the application of the two-speed DCT in EVs is accordingly discussed in this article.