The latest third generation of Getrag Transmission Systems dual-clutch transmissions features electro-mechanic shift drums for shift actuation and electro-hydraulic pump actuation for clutch actuation. The pump actuators integrate a pump and the electric motor driving it. These modules can be flexibly placed anywhere within the transmission. Pump actuation technology was launched with the 7DCT300 and is gradually being introduced in additional dual-clutch and hybrid transmissions.
Smart Actuation & Cascading Gears
A smart, demand-controlled actuation is the key for efficient automation. With Smart Actuation, we create a modular standard for dual-clutch and hybrid transmissions.
Dual-clutch transmissions use the same low-loss technology as manual transmissions, supplemented by the actuation components for automated shift and clutch operations. A low power consumption of the actuation ensures maintaining high efficiency. Since their introduction, our dual-clutch transmissions have proven to be exceptionally efficient automated transmissions.
Combined with the 7DCT300, Smart Actuation requires a mere 30 Watt of electrical power on average in the NEDC. This low consumption does not have any significant effect on fuel consumption, thus preserving the high efficiency of manual transmissions with dual-clutch transmissions. In practice, an intelligent shift strategy can even help to reduce real-life fuel consumption.
The modular design of Smart Actuation is another advantage: pump actuators as well as the shift drums belong to a common Corporate Transmission Architecture, meaning they can be used across all of the latest dual-clutch and hybrid transmissions.Technical progress effects every member of the transmission portfolio, and product variants can be designed by modifying the software instead of having to develop new hardware. These advantages will become even more crucial in the future, as they can be seamlessly transferred to hybrid transmissions.
Virtual gears offer optimal options for even more efficient Dual clutch transmissions. They are created by interconnecting several gears through both sub-transmissions.
Dual clutch transmissions are a type of transfer box gearing and therefore offer the same efficiency advantages as manual transmissions, with the addition of actuation components for automatic shifting and clutching. Cascaded gears help reduce the added weight and larger installation space required by automation.
The first gear is the largest and heaviest in a transfer box gearing gear set. Its design as a cascaded gear therefore offers the greatest optimization potential for package and weight reduction.
Cascaded gears are being used for the first time in dual clutch transmissions 6DCT150 and 6DCT200. Here the first speed is achieved using a bridge with the gears of the second, fifth and sixth speeds.
This mainly allows extremely compact dual-clutch transmissions for subcompacts and therefore efficient automation in this vehicle class.
Furthermore, cascaded gears can also be used for overdrive gears, for example, because they are reasonable for expanding the number of speeds possible when they are used at the lower and upper gear levels. This prevents the inherent disadvantage of sequential shifting in the most frequently needed gear levels. Instead, it offers a reasonable gear ratio spread while maximally reducing weight and installation space.