AT or DCT? MCT - The best of both worlds! Synthesis and Functionalities of Multi-Clutch Transmissions

摘要

The synthesis program "PlanGear", developed by ZG GmbH, is able to generate mixed forms of automatic and double-clutch transmissions. This allows the combination of the specific advantages of both concepts. Automatic transmissions (AT) generally consist of a start-up element, multiple planetary gear stages and load-shift elements. The gears are power shifted. A significant advantage of this design is the high power density, mainly due to the multiple use of planetary gear stages within various gear steps and their internal power-split. Hydraulic losses through open shift elements as well as leakage in the hydraulic oil supply of clutches at rotary feedthroughs are relevant for the efficiency. Thus, the general goal in the development of automatic transmissions is the reduction of the number of load-shift elements. Double-clutch transmissions, also known as dual-clutch transmissions (DCT) normally consist of two multi-disc friction clutches which are actuated alternately to switch gears. Synchronized dog clutches set up the power flow of the next gear parallel to that of the actual gear. The different gears are represented by cylindrical gear pairs with different ratios. Socalled "winding gears", meaning the multiple use of single stages, are rarely in use. Advantageous when compared with AT are the comparatively smaller efficiency losses through nonengaged shift elements.