Advances in the Automotive Systems: An Overview of Dual-Clutch Transmissions

After a brief description of the most important “automatic” solutions, this paper explores the advantages of automated manual ones, particularly in the dual-clutch transmission (DCT) configuration. This mechanical architecture offers gear shifts without interruption of power (the so-called “torque gap”), by applying the engine torque to one clutch just as the engine torque is being disconnected from the other one. The result is jerk-free gear change with the same driving style found in a conventional automatic combined with the efficiency of a manual transmission. It is as smooth as the most automatics, but more economical; it is as easy to drive as a standard auto, faster and more responsive than even the sportiest manual gearbox. The two clutches are engaged alternatively in different speeds and power transmission continues during a shift through the control of clutch slippage. This outstanding design allows automakers to achieve what previously had seemed impossible: to improve both comfort and sportiness, whilst at the same time fulfilling the essential requirement of reducing fuel consumption. Historical evolution, future market forecast and recent patents complete the paper, while recent modelling approaches and proposed control strategies are referenced. Keywords: Automatic transmission (AT), automated manual transmission (AMT), dual-clutch transmission (DCT), automotive mechatronics, torque gap and gearbox