New environmental and fuel efficiency legislation coupled with advances in electronics and manufacturing techniques have triggered new automated transmission technologies, writes Matthew Beecham. The most likely winner that will replace traditional automatics and boost market penetration of automated transmissions will be the dual clutch transmission (DCT).

The direct shift gearbox, powershift gearbox, twin-clutch gearbox are just a few of the terms used to describe the dual-clutch gearbox. The gearbox concept combines the advantages of a conventional manual shift with the qualities of a modern automatic transmission. It originated in motor sport and is characterised by having two part gearbox units, which operate the odd and even gears, respectively. It means that when changing gear, the engine torque is transferred continuously from one gear to the other. The result is gentle, jerk-free gear changes with the same relaxed driving style found in an automatic combined with the efficiency of a manual transmission.

Germany’s LuK is among those working on dual-clutch transmission technologies.  “We have a lot of projects involving the delivery of the double clutch, the clutch actuator and gear actuation mechanism to independent manufactures and in-house automaker operations.,” said  Dr Wolfgang Reik, Vice President of R&D, LuK GmbH.  “Most automakers, except a few Japanese companies, are developing double clutch transmissions.  By 2010, we shall see a number of automakers offer double clutch Transmission Systems.  Some of these projects we are working on and, of course we have some competitors who are also working on other projects.  The double clutch transmission could be useful in every car.  Whenever you can get losses out of the drivetrain then that has a double benefit.  First, it reduces fuel consumption and CO2 emissions.  Second, the losses that are saved thereby help the vehicle accelerate faster, giving it a sportier feel when driving. A double clutch system thereby offers double benefits.”

In addition to LuK, BorgWarner is working on dual-clutch systems. The VW Group pioneered this technology and continues to push dual-clutch technology in Europe. VW co-developed the DSG with BorgWarner, making use of the supplier’s DualTronic wet-clutch and control-system technology. In addition to its performance and fuel economy benefits, one of the interesting things about this dual-clutch is the fact that it can be “tuned” via software thereby changing the personality from sporty to limo-comfortable.  “It is a very compelling feature for the automotive industry,” said Dr Bernd Matthes, Vice President, BorgWarner Inc and President & General Manager, Transmission Systems, BorgWarner Inc.  “It means that given one set of hardware, you can tune the feel just by changing the software to the different needs of vehicle brands in a very easy and cost-effective way.  Besides the tuning factor, the other factor that is very important these days is the fuel efficiency and emissions aspects.  It is the most fuel efficient transmission technology out there that is still providing a substantial gain over any other automatic transmission in the marketplace.  That makes it very appealing for customers.”

To date, BorgWarner has announced five programmes with four customers, including Volkswagen/Audi, GETRAG, another unnamed European OEM and Shanghai Automotive Industry Co (SAIC) in China.  Matthes added:  “China is a very interesting market for us.  SAIC is applying BorgWarner’s dual clutch technology to its new [Rover 75-based] Roewe 750.  We are involved in developing and providing five production modules, which include the dual clutch, torsional vibration damper, hydraulic controls with shift actuation, synchronizers and hydraulic pump.  The transmission assembly is being jointly developed by Shanghai Automotive Gear Works (SAGW) and GIF, a German engineering company.  Transmission assembly production will take place at SAGW in China. Beyond SAIC we are working with some of the key players in that marketplace on programmes and we are very confident that there will be an additional production programmes going into the future.”

Two years ago, Bugatti unveiled details of its revolutionary seven-speed twin-clutch DSG gearbox, subsequently launched in its Veyron car. Developed by Ricardo, the unit handles the massive torque produced by the Veyron’s 1001bhp 16-cylinder engine. Since then, Ricardo has been pushing back the technical boundaries of dual-clutch systems.  “While the European market is currently dependent on manual transmission technology, the driver for automation is essentially emissions legislation,” said Jim Hey, Chief Programme Engineer, Ricardo.  “We see a future where manual transmission may even be legislated against.  That could create an environment where you need automated manual transmissions, whether that is a DCT or a smarter AMT or something in between.  Clearly, there is a big difference between an AMT and a DCT so what is really required is the drivability of a DCT but with the parts count and cost closer to an AMT.”

Ricardo’s Lee Sykes, Global Product Group Director, Transmissions and Drivelines, added:  “To summarise our development targets for next generation DCT, we are aiming to have a sub-system of technologies and an architecture that can applied to AMT and DCT in a modular way to potentially add upgraded parts all with a view to improving efficiency compared to current systems by 5 – 10%, substantially improve packaging and improve cost at least 25%.  At a paper study level, we believe that we shall be approaching those targets. But as a company we need to go beyond paper and in one year’s time, certainly on the DCT side, we are looking to have running vehicles. We want to be able to go to the market not with what we think can be done but what can actually be done.  We should have a driveable vehicle in one year.”

UK-based Vocis Driveline Controls was formed last year by four engineers and a project manager who left Ricardo to establish their own business specializing in driveline control systems and programme management. All five have hands-on experience of developing transmission control and software systems, specifically the emerging DCT technology.  Although a young business, Vocis Driveline Controls has kept a very low profile.  Until now that is.  The company used this year’s SAE show in Detroit to take the wraps off its DCT control system. “A dual clutch transmission is mechanically well understood but controlling it is extremely complex,” said the company’s managing director, Mike Everitt.  “It’s affordable and robust, but the quality of the transmission as perceived by the driver is largely dependent on the quality of the control strategies.  Getting this right has previously proved exceptionally time consuming.  Our second generation technology solves this problem and brings a vast range of new benefits as well.”  The new technology, provisionally called Siena, is a DCT control platform that is independent of any specific hardware technology or vehicle manufacturer.  As well as delivering a new level of DCT control, it can integrate controls for active differentials and torque management and coordinate with the complete range of chassis systems, including antilock braking, electronic stability control and traction control.”

Given the increased demand for automated transmissions, manufacturers see an overall decline in demand for conventional clutches. Bernd Stockmann, manager, Continental Temic’s Transmission Profit Centre within the Chassis & Powertrain Business Unit, told us:  “We are seeing an overall increase in step automatic transmissions such as DCT and CVT systems.  Consequently, we expect to see manual transmissions decrease over the next few years. … DCTs will gain market share continuously over the next few years although it depends on several circumstances based on the automaker’s and transmission manufacturers’ strategies.  At the moment, however, Europe is the fastest growing market for DCTs. There is [also] significant interest at the moment in North America.  And we know that there are some programmes already released.  In Asia, right now there is a lot of interest from automakers and car transmission manufacturers.  But I do not see Japan as being a big market for DCT in the next five years due to their concentration on CVTs.  That situation is unique because of the driving characteristics in Japan.  On the other hand, the Chinese and South Korean automakers are very interested in DCT technology.”

Continental Automotive Systems developed a control unit for a dual-clutch transmission, which entered production in 2003.  In bracing itself for a booming DCT market, the company has further developed its control unit.  Stockmann added:  “We are using a new concept of mechanical components which is based on our customer requirements. We are currently in the process of launching four additional double clutch programmes, starting production this year and next. Overall, we have about 50 different applications for VW Group.  That transmission control unit is used across a number of different platforms for the group.”

“Although there is a general trend toward automated gearboxes, there is still a development potential,” said Niklas Schulz, Product Manager, Powertrain, ZF Trading. “Technologies like dual clutch or semi-automated transmission as well as the car parc growth in Eastern Europe keep the level of demand.”

So just how fast could the DCT market grow in Europe?  “At the moment, we see DCT at about 1% of the market which is on a par with CVTs,” adds Hey.  “By 2015, however, we expect 10% of the market will be DCT, mainly driven by the B- and C-segment vehicles.”  Sykes concludes that the market will be fairly diverse by 2015, adding:  “There will be planetary automatics, DCTs and maybe a modest resurgence of AMTs as well. DCT will be a sizeable part of the market but I don’t think that it will dominate.”

See also: Global market review of OE gearbox clutches – forecasts to 2013 (download)