New LuK Multi Function Torque Converter Meets Challenges of Modern Diesel Engines
LuK has introduced an innovative multi function torque converter (MFTC), which overcomes the challenges imposed onto start-up devices for automatic transmission by modern and highly efficient turbo-diesel engines. Thus, a component has been launched that allows to combine environmentally-friendly diesel technology, which is on a continuous rise in the USA, with the demand for comfort in an automatic transmission.
The automotive industry is abuzz with the story of the turbo-diesel engine - and for a good reason. These modern engines provide substantial fuel economy benefits of up to 25% along with low speed torque that makes driving fun. However, at least in the USA, to mate an automatic transmission and a diesel engine has been a rare thing. Why is this so?
Diesel engines impose several challenges to the automatic transmission:
Firstly, the combustion process is far more violent, which leads to NVH problems.
Due to high idle speeds, which are necessary to reduce particulate emissions, idle losses in the torque converter are higher. With an idle speed of approx. 800 rpm and a typical torque converter designed for 400 Nm, these losses are about 3 kW! That is one third of the average power required to actually drive the city cycle.
Eventually, the turbo charger is difficult to accelerate with the torque converter holding down engine speeds. This leads to a very sluggish launch with an automatic transmission, well known as and often critizised also for its safety impact as „turbo-lag“.
The revolutionary LuK MFTC layout solves these problems. By means of an additional clutch, the impeller inertia can be disconnected from the engine.
Thus, aforementioned NVH problems, won’t occur as the impeller inertia is connected to the transmission when the converter is locked. This lowers the resonance frequency of the driving mode below idle speed and allows the lock-up clutch to be closed in all driving conditions.
The idle losses are eliminated by disconnecting the impeller when the vehicle comes to a standstill, for example at traffic lights. This saves a significanct amount of fuel which would otherwise be used to turn the impeller.
Finally, the impeller clutch can be modulated during the launch, resulting in a launch to be controlled as in a dual clutch transmission. The engine speed is allowed to quickly rise, which speeds up the turbo and provides maximum torque – and the „turbo-lag“ is a thing of the past!
Additionally, the MFTC offers torque multiplication which is what makes it the preferred choice for gas engines, and results in driving dynamics, even superior to manual and dual clutch transmissions.
The Multi-Function Torque Converter solves the diesel engine challenge with improved fuel economy of up to 5%, elimination of vibration and boom and dynamic launch performance with 0-60 mph times reduced by up to 0.8 seconds compared with a conventional torque converter.
The Schaeffler Group, with its brands INA, LuK and FAG, and approximately 63,000 employees at more than 180 locations in 50 countries generates group sales of more than 8.3 billion euros (FY 2006) and ranks amongst the leading rolling bearing manufacturers and suppliers to the automotive industry worldwide.
