Dual-clutch transmissions stand out not only for their high degree of efficiency and multiple gear set designs. The way they behave can also be dictated by the flexible use of software.
Changing Gear as Required
As with converter transmission with planetary gear sets the dual-clutch transmission is a powershift transmission. Gears are changed without interrupting the tractive force. With dual-clutch transmission, engaging a gear and the procedure for changing gear used by the driver are actually separate procedures. The next gear is already engaged in the background in the passive sub-transmission. It is then activated by one clutch closing and the other one opening.
To a large extent, the 'overlapping gear change' occurs freely. By way of example, the second clutch can be closed faster to give the gear change a sportier feel, or the overlap can be programmed in such a way that the gear change is hardly noticed. This allows the car manufacturer to adjust the behaviour of the automatic gearbox to the features of the brand and the wishes of its customers. Some manufacturers also offer driving programmes allowing different characteristics to be selected for a vehicle.
The overlapping gear change is programmed by software. When which gears are engaged and how the dual-clutch is activated is set out in the Transmission Control Unit (TCU). The transmission control units communicates with the engine management unit and other vehicle functions.
Communication between these functions will continue to grow. By way of example, traffic data or information about the topography of the route can be used to optimise the vehicle's behaviour, including the transmission. Communication between vehicles and with the infrastructure will also influence future drive systems. The transmission of the future will combine excellent internal efficiency with intelligent behaviour within networked traffic.
Software in the Developement of Transmissions - Matthias Heß reports
The development of transmission software and interdisciplinary cooperation with developers from other vehicle areas are constantly gaining in significance at GETRAG.