Getrag introduces new 7-speed dual clutch and derivative hybrid transmissions; applications from mild- to plug-in hybrids
|Getrag PowerShift Transmission 7DCT300. Click to enlarge.|
At its fifth biennial Drivetrain Forum in Cologne, Getrag presented the seven-speed dual clutch transmission Getrag Powershift 7DCT300 and a hybrid derivative, the Getrag Hybrid Drive 7HDT300. The company said that the new transmissions complete its product portfolio to provide total coverage in terms of torque output and application size.
The transmission is designed as a product for the global market with a consistent common-part strategy. The main functional elements such as dual clutch, gearshift, actuators, control unit and synchronization are designed for various applications as common parts. The common-part strategy makes it possible for Getrag to implement all customer versions on only one production line and therefore to react quickly and efficiently to market requirements.
We have developed each module with enough flexibility and breathing space to make it easily adaptable to the different attributes required by different local markets. Benchmarking the 7DCT300 against CVTs and automatics has made the transmission best-in-class for launch, fuel economy, NVH, cost and ease of hybridization.—Getrag Chief Technology Officer Didier Lexa
7DCT300. The 7DCT300 is designed for use in mid-sized and compact vehicles with front-transverse layouts and maximum torque of 300 N·m (221 lb-ft). It is the first transmission of a modular family of front-wheel-drive automatics which will be extended at the high-end with the seven-speed transmission 7DCT500 and at the low-end with the six-speed transmission 6DCT150.
The 7DCT300 features a wet dual clutch, electro-mechanical gear actuation and new electro-hydraulic clutch actuation, enabling significant reductions in fuel consumption compared to earlier transmissions. The oil in the 7DCT300 is fill-for-life, which results in considerable advantages in terms of maintenance and running costs.
The 7DCT300 can be combined with all-wheel drive as well as an engine start/stop function and sailing function. The actuation system allows this full range of advanced economy functions without modification of the hardware since the transmission actuation system can operate fully independent from the combustion engine running or being off.
The shortened response times during the gearshift (compared to conventional multi-step automatic transmissions with a torque converter) allow for greater driving pleasure and provide a more direct driving experience. With a transmission control system that allows individual adaptation of all shifts, it is possible to provide multiple driving profiles (comfortable, sporty, etc.) per choice of driver.
Compared to the conventional hydrodynamic torque converter, dual clutches offer the advantage of software strategy controlled actuation resulting in optimized vehicle launch and gearshift processes with respect to the dynamics and driving comfort. In addition, Getrag Powershift transmissions combine the high degree of efficiency of a manual transmission with an application-specific shifting strategy, thereby resulting in a considerable reduction of fuel consumption and CO2 emissions compared to conventional automatic transmissions.
The transmission control, embedded in an attached stand-alone unit, also works directly with the engine management system.
Getrag uses a newly developed electro-hydraulic on-demand clutch actuation to ensure fast and robust controllability of the wet clutch while lowering the needed actuation energy to a minimum. The actuator system for the gearshift actuation is based on shift-drum technology and runs electromechanically. As a consequence, the 7DCT300 is, without any hardware change, ready for start/stop functionality and extended sailing.
The 7DCT300 front-transverse transmission has seven forward gears and one reverse gear. The even (2, 4, 6, R) and odd-numbered gears (1, 3, 5, 7) are divided into two sub transmissions. The ratio spread is up to 8.6. The engine and the two partial transmissions are connected by means of a wet dual clutch.
The transmission’s low dry weight of approximately 65 kg (143 lb) makes it compatible with future lightweight vehicle platforms.
|GETRAG PowerShift Transmission 7HDT300. Click to enlarge.|
7HDT300. The Getrag HybridDrive 7HDT300 is the hybridized version of the DCT300 Powershift transmission. The seven-gear transmission offers scalable hybridization from mild hybrids to plug-in architectures capable of pure electric driving. Depending on the level of hybridization, there are different power levels of the electric traction motor available.
The mild-hybrid version of the 7HDT300 is equipped with an 15 kW electric traction motor based on a 48 V system. With this hybrid level pure electric driving of up to 20 km/h (12 mph) is possible and fuel improvements of 15 to 20% in the NEDC are achievable.
The full-hybrid version uses a 40 kW electric traction motor allowing pure electric driving of typically up to 50 to 60 km/h (31 to 37 mph). Such a full-hybrid version enables fuel improvements of 24% up to 30 % in the NEDC compared to the conventional version.
Plug-In Hybrid functionality is reached by applying a more powerful electric traction motor with a peak power of more than 75 kW. This enables pure electric driving with a maximum speed of more than 130 km/h (80 mph). Depending on the overall battery system fuel improvements of up to 80 % in the driving cycle compared to the non-hybrid version are possible.
With the new actuation system for dual clutch and for gear shifting, the hybridization is realized without any additional auxiliary hardware component; i.e., unlike some other hybrid drive systems, the 7HDT300 hybrid transmission does not need any additional actuation to enable the hybrid functionality. An integrated electric on-demand oil pump from the the 7DCT300 provides the oil-cooling in a compact overall design.
All hybrid versions of the 7DCT300 are based on an axial parallel high-speed traction motor to realize a compact installation space and a high power density. The transmission integrates the same type of high-speed e-motor as for the other hybrid versions of the company’s planned six-speed 6DCT150 and seven-speed 7DCT500.