transmission_technology_international_变速器技术2010-09_(2).pdf

Accelerating into the future 24 OEM intErviEw Fiat Transmission Technology International September 2010 Fiat may be steeped in the tradition of manual transmissions but that does not mean the Italian car maker s sole focus is on conventional gearbox technology n Being the dedicated R the second focuses on the substitution of tapered roller bearings by driveline angular contact ball bearings It s important to note that all the above fundamentally depend on application Bearing breakthrough Friction optimized anti friction bearings are enabling crucial CO2 emissions savings 30 Case study SKF Transmission Technology International September 2010 requirements and which way they will be ranked in terms of importance and favorability For example important bearing functions such as stiffness levels and service life cannot be sacrificed for the sake of a minimized power loss As a result of all of this the SKF energy efficient bearing portfolio consists of the following bearing types energy efficient tapered roller bearing driveline angular contact ball bearing ball pinion unit and the hybrid pinion unit All of these advanced technologies from SKF can be utilized in any bearing position of gearboxes and axle drives thus helping the powertrain to become more efficient in terms of emissions output TTi the technologies in sKF s energy efficient bearing portfolio can be utilized in any bearing position of gearboxes and axle drives Be part of this exciting opportunity To find out more about the roles that we are recruiting for visit We re recruiting research the vehicle needs the same amount of torque to pull away but to provide it the CVT must take the fl ywheel through a completely different speed maneuver Because a fl ywheel s inertia is fi xed its acceleration is a function of torque and so to receive torque from it you decelerate the inertia That is relatively simple with our CVT The system asks for a torque within the CVT the corresponding hydraulic pressure is applied and the ratios sort themselves out Heavy vehicles that stop and start frequently have the most to gain from such a system The Flybus project using an Optare Solo city bus aims to demonstrate fuel savings in the region of 20 but at less expense than current bus hybrid systems a typical hybrid system can increase the vehicle s cost by 50 or more CASE STUDY TOROTRAK 45 September 2010 Transmission Technology International Torotrak s experience in optimizing its technology s application to different sized vehicles with different duty cycles will be useful The research projects led by Jaguar and Ricardo will use Torotrak s technology in fl ywheel hybrid systems for large and small passenger cars Torotrak is also exploring areas where its technology could be further applied as an ancillary drive such as fan and supercharger drives Its Rotrak joint venture with the supercharger company Rotrex is developing a variable drive compressor using Torotrak s CVT unit Vehicles overall effi ciency is becoming more important The challenge for manufacturers is to determine the most cost effective and effi cient for their customers TTi Optare is partnering with Torotrak Ricardo and Allison Transmission to integrate an advanced CVT fl ywheel KERS system into its Solo city bus application The research consortium expects to realize fuel savings of around 20 Request your FREE copy of Transmission Technology International magazine at SUBSCRIBE NOW ONLINE READER ENQUIRY SERVICE ALSO AVAILABLE copy of Transmission Technology International AN ENGINE TECHNOLOGY INTERNATIONAL PUBLICATION September 2010 What s new Ford s high tech auto Getrag s dry clutch DCT design for Renault BorgWarner s advanced eGearDrive system Sergio Cairola transmission platforms vice president Fiat Powertrain Technologies Jeffrey Baran executive director of transmission program execution General Motors Rolf Najork product development vice president Getrag Geared to the future Which designs will win and lose in a changing world of transmissions INTERVIEWS n From planetary automatic transmissions it is known that a fixed gear ratio with a planetary set can be selected by connecting either one of its three rotational members ring gear sun gear or the carrier to the transmission housing This connection is usually established through a wet multiplated brake unit so that synchronization with the housing is possible with retained power transfer DTI s powershift technologies use such a brake controllable planetary gearset as a short term torque bypass while the main transmission shifts towards the next gear One may compare the functionality to a limited slip differential LSD which controls the distribution of left and right drive shaft torque using a slip controllable clutch The functionality of the brake controllable planetary gearset can be used to fill torque gaps that occur when shifting an AMT from one gear to the next The installation of a planetary gearset and brake in the bellhouse leads to package neutrality for CSC equipped AMTs The combination of an AMT and brake controllable planetary gearset is termed Powershift AMT Because the planetary gearset is only loaded during shift instances the accumulated loading time of the gearset is about one order of magnitude lower than the lifetime requirements of the transmission s final drive The material lifetime requirements of the dry brake disc for the powershifting functionality are roughly the same as the material lifetime requirements of the main clutch The cost effective powershift module is particularly interesting in combination with a five speed A MT installed in A B class Transmission evolution A pioneering new structure is helping to realize a number of important advantages over existing dry DCT systems vehicles In this vehicle segment usually five speed manual transmissions are installed or alternatively relatively inefficient four speed automatic transmissions The main benefit of the Powershift AMT is that the standard five speed MT design can be dressed up towards being a substitute for the four speed AT or a five speed AMT and as such it constitutes a very lucrative step for producing the MT AMT and Powershift AMT systems on the same production line The brake controllable planetary gearset can also be used as the main clutch in a six speed DCT 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 six speed DCT structure is such that when the engaged brake is in the planetary module it establishes gears one three and five whereas the engaged clutch establishes gears two four and six The gear pair used to establish the second transmission ratio is also used to establish the first gear by engaging the brake of the planetary gearset The planetary gearset then realizes a pre reduction for the second gear ratio and as such constitutes a first gear equivalent ratio Furthermore the fifth gear is composed by that same pre reduction and a direct mesh between a selectable fifth gearwheel and the output gearwheel In most other layshaft transmissions including DCT putting a gearwheel at that specific location makes no sense as the resulting gear ratio is then too high In addition to this the space above the output gear is usually occupied by an input shaft bearing and or a clutch dis engagement system The discussed new DCT structure renders a number of important advantages over existing dry DCT structures For example the single layshaft re uses at least one gear pair first and second and a double meshing output gear justifies the installment of the additional planetary gearset without the penalties on length compared to a standard single layshaft six speed manual transmission A second advantage is to do with its slender design because the first gear pair can be left out and this enables a less asymmetric loading as well as a shorter center distance between input and output shaft and thus a more slender transmission leaving more room for top mounted actuators Other important advantages that the DCT structure allows is active cooling 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 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 s 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 inertia of the engine when compared to a manual TTi 46 Case study DTI Transmission Technology International September 2010 the new dCt structure focuses on a new single layshaft the brake controllable planetary gearset as the main clutch in a dual clutch transmission structure September 2010 Transmission Technology International Request your FREE copy of Transmission Technology International magazine at SUBSCRIBE NOW ONLINE READER ENQUIRY SERVICE ALSO AVAILABLE A replaces metal where heat humidity and chemical resistance are major considerations Ixef PARA polyarylamide High strength polyamide with