Compact DCT

The brake-controllable planetary gearset seen in the Powershift AMT can also be used as the main clutch in a 6speed DCT (Dual Clutch Transmission) structure. As a first DCT-clutch, it must also perform functions such as vehicle launching, creep and hill-hold. Therefore, sufficient cooling capabilities of the (planetary) brake module are required. The 6speed DCT structure is such that when the brake is engaged in the planetary module, it establishes gears one, three and five, whereas the engaged clutch establishes gears two, four and six. Contrary to a normal clutch, the braked planetary gearset constitutes a gear ratio in itself.
This enables double usage of at least one transmission gearpair (e.g. the gear-pair for the second ratio can also be used for the first ratio) as well as some other space-saving and cost-down principles that can not be reached by standard DCT layouts.
A second important advantage is that the new DCT structure allows active cooling of the brake pressure plates. The brake system can be actively liquid cooled to guarantee the lifespan of the launch-brake when used for heavy hill/trailer launches, hill-creep and long stop/start traffic circumstances. As a result, it enables capabilities that are seen only in wet-plate or torque-converter automatics while still maintaining the high efficiency of the manual transmission structure. Liquid cooling of the dry brake system can be established by integration of cooling channels (integrated with the engine cooling system) in the static brake pressure plates.
Another benefit that is realized with the new structure, is that the heat sinks of the brake and clutch are mechanically and thermally separated. As such, the functionality of the on-coming clutch or brake is not influenced by the temperature history of the off-going brake or clutch. This decreases the amount of calibration work of this DCT structure. Finally, the pressure-plates of the brake in the planetary gearset are non-rotating and therefore this new dry DCT structure does not noticeably increase the total rotating inertia attached to the engine when compared to a basic manual transmission.

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