If we compare dry clutches with oil bath (wet) clutches, we can safely say that the former dissipate energy only during the actual slipping phase of the gear change and on pick-up, whereas wet clutches, which always operate in an oil bath, introduce losses due to viscous friction such as those of conventional automatic transmissions even when they are not in operation. They also require forced cooling with oil and therefore continuous energy expenditure to drive the dedicated oil pump (absent in the case of dry clutches).
Lastly, a "Wet" automatic transmission requires approximately 4.8 litres more gearbox oil than the "Dry" version, again for reasons of clutch cooling (in this way, weight is added and losses due to splashing increase). When all these effects are added together, a dry transmission is found to be approximately 6% more efficient than the corresponding wet one in terms of consumption. Last but not least, the advantages of the "Dry" clutch include the lower running cost and the increased ease of maintenance. http://www.alfaromeopress.com/press/detail/11325作者: coupeelvin 時間: 2013-2-12 23:53
If dry clutch is so good, why there is wet clutch in the world? There are many technical challenges for dry clutch automatic manual transmission.作者: 古惑強 時間: 2013-2-13 09:22
In the VW world, wet clutch setup seems more reliable and able to handle higher torque than the dry configuration.
For those Golf GT with 7speed dry clutch config, once modified from stock 140hp to 200hp, the dry config DSG gearbox is known to have a lot of issues!作者: letsrock 時間: 2013-2-13 09:38
Fiat Powertrain Technologies
Fiat Powertrain Technologies has developed a dual-clutch transmission with Magneti Marelli and BorgWarner. Magneti Marelli delivers the control system which integrates BorgWarner's hydraulic actuation module into its own power and transmission control units.[19] It can handle torque inputs of up to 350 N·m (260 lb·ft), making it the highest-torque dry clutch application. Its weight of just 81 kg (179 lb), complete with oil and transmission control unit, its compact three-shaft architecture, especially axially, allowing it to be installed in a wide range of B- and C-segment vehicles. Fiat Powertrain is an independent company looking to maximize its sales to third party organizations, so the DCCT system is likely to go not just to Chrysler-Jeep, which Fiat now controls, but to outside customers, as well.[20]作者: 古惑強 時間: 2013-2-13 11:21
