Clutches with positive fit for Automatic Transmissions

摘要

Despite dynamic developments in the areas of hybrid technology and electrical mobility, traditional drivetrains will continue to play a significant role in the future. The percentage of automatic transmissions will grow at the global level, with DCTs and CVTs gaining market share, while traditional torque-converter transmissions will stay at approximately the same level. The fuel savings that can be achieved with the particular transmission systems will be a key factor in their success. Whereas dual clutch transmissions can be made up of a wide variety of mechatronic systems available on the market (hydraulic, hydraulic with power pack, electro-mechanical), traditional torque-converter transmissions continue to rely on integrated hydraulics with common oil circulation in the transmission and mechatronics system. The potential for on-demand provision of shifting energy is thus basically limited. Significant controlling factors with respect to automatic transmissions are the drag power and contact forces of the multi-disk clutches and brakes. Friction and the related required number of frictional elements result in significant drag loss when the shifting elements are disengaged. Conversely, contact pressure in the engaged state requires the provision of hydraulic oil, which can also be consumption-relevant if the related shift element determines system pressure. A possible solution to this problem could be the use of dog-type shift elements; however, these are not capable of power shifting and command considerable control complexity to ensure comfortable actuation. The use of shifting elements that, in their elementary structure, are based on synchronizers makes it possible to replace multi-disk clutches for certain applications. Their special design combines power shifting capability with the advantages of form-locked torque transmission.