The VW Group pioneered dual clutch technology and continues to push dual-clutch technology in Europe. BorgWarner played a key role in the development of VW’s DSG 6-speed automatic gearbox, which combines the smoothness of a state-of-the-art torque converter with the fuel efficiency of a lighter and cheaper to manufacture 6-speed manual. BorgWarner is continuing to push back the technical boundaries of dual-clutch innovations. Its DualTronic clutch and transmission control technology enables a conventional, manual gearbox to function as a fully automatic transmission while delivering improved fuel efficiency and enjoyable drive experience. In this interview, Matthew Beecham talked with Bob Blakely, marketing director of BorgWarner Drivetrain Systems.
just-auto: What is the greatest challenge facing automotive transmission developers and suppliers?
Bob Blakely: It is difficult to respond with any one challenge that is greatest. We see three related factors:
First, there is a never-ending demand for higher torque density in vehicle powertrains. Engine technologies such as common-rail diesel injection, gasoline direct injection and turbo-charging produce specific torque and power outputs that were not possible just a few years ago. Not only must transmissions handle greater engine torque and power output, their developers are expected to expand ratio span and/or add ratio steps with no additional space allotted to powertrain packaging.
Second, managing powertrain noise, vibration, harshness (NVH) demands ever greater creativity. Higher torque density means more intense power pulses, thus more severe torsional vibrations at the crank output. Furthermore, the current trend of engine downsizing often means high output four cylinder engines are installed in higher specification vehicles, where customers have come to expect the refinement of six cylinder engines. Add the growing demand for engine stop-start capability, and it is obvious that effective torsional damping, smooth launch, and seamless shifts are tougher challenges than ever before.
Third, the bottom line is always total system cost to the vehicle OEM, and the end user. Worldwide, government mandates for greater fuel efficiency translate into OEM demand for greater powertrain functionality. At the same time, consumer expectations for performance, refinement, and durability grow every year, while those same consumers are conditioned to expect continuous improvement at little or no additional cost. Satisfying the demands of the marketplace, while keeping the incremental cost of new technologies in check, is arguably the most intense challenge of all.
just-auto: Back in 2007 – and following Bernd Matthes’ development — BorgWarner was the only supplier on the market with a DCT system. Since then, a number of transmission developers and suppliers are offering DCTs in what is now a blossoming market.
Bob Blakely: BorgWarner entered the DCT segment by leveraging its experience, expertise and product technology from traditional step ATs, applying it to dual-clutch architecture. It is certainly true that the DCT market has blossomed, and BorgWarner has worked hard to maintain its strong market position.
just-auto: How have you maintained your technological lead?
Bob Blakely: At the heart of BorgWarner’s DualTronic® technologies are two key core competencies in wet (oil bath) friction clutches and electro-hydraulic solenoids, which we continue to evolve and refine to maintain our competitive edge. Our latest friction materials deliver the industry’s highest ever thermal capacity, enabling operation in low oil flow environments. Our latest solenoid designs deliver greater precision while reducing control system leakage, thus minimizing energy consumption.
just-auto: What is in the pipeline?
Bob Blakely: We continue our work in Asia supporting DCT development programs with several OEM customers. In Europe, we are applying our expertise in high pressure (40-50 bar) solenoids and hydraulics to the next generation of on-demand control systems, suitable for both wet and dry dual clutch applications.
just-auto: With electric vehicles still at an embryonic stage, fuel-efficient transmissions such as DCTs and CVTs are likely to enjoy a greater market share. Is that right?
Bob Blakely: BorgWarner is an active participant in the electrification movement, with its eGearDriveTM gearbox for EVs. However, we would agree that the technology is in an embryonic stage. And furthermore, we expect that EVs will be practical and cost effective for urban duty cycles and predictable fixed route operations long before they make sense for more varied mixed use. Thus, we expect IC powered vehicles will be with us for many years to come.
just-auto: How do you see this technology evolving?
Bob Blakely: Near to mid-term, we see demand for more efficient transmissions in IC powered vehicles growing stronger. And, while CVTs are continuing to grow, the compound annual growth rate projected for DCT long term is far greater. BorgWarner believes DCTs have stronger growth prospects because parallel shaft gearing is inherently more efficient than belt/chain and sheave variator CVTs. Although CVTs demonstrate competitive fuel economy in low-speed high density urban traffic, this is also the environment where EVs will be most competitive in the future. DCTs, we believe, have greater long term potential.
just-auto: Today, approximately 45% of the world’s vehicles are equipped with manual transmissions. What do you see happening to that manual gearbox fitment going forward and what will it mean for BorgWarner?
Bob Blakely: We predict that manual transmissions will remain a compelling value in cost-sensitive markets for many years to come, but automated transmissions in various forms will continue to gain share steadily. In developing markets, like China, OEMs have mastered manual gearbox production. In times of rapid growth, they are able to add more manual capacity quickly and at reasonable cost. Nevertheless, consumer demand for automation continues to grow.
We continue to believe that DCT is a solution well suited to China and other developing markets. Local OEMs are well positioned to leverage their existing expertise and investment in parallel shaft gearbox production, while BorgWarner is positioned to supply the proprietary clutch and controls technology needed to make those gearboxes DCTs.
just-auto: DCT is still an optional extra and expensive to fit. I guess until one of the automakers makes it standard, we shall not see a leap in installation rates. What are your market fitment expectations for DCT in Europe by, say, 2015?
Bob Blakely: DCT is a premium feature, although we believe it is cost competitive with the latest step-ratio planetary automatic transmissions. Given current OEM development plans and expected volumes, BW believes DCT installations can reach 10-12% of total (western & eastern) European light vehicle production around 2015.
just-auto: As I understand it, a number of automakers have introduced DCTs in their fleet, including VW, BMW, Audi and Ford. When these automakers choose a DCT, what factors to they consider? i.e. in terms of torque, driver comfort and performance?
Bob Blakely: From the start, OEMs offering DCT have introduced the option on their higher performance models, and in combination with diesel engines. More recently, we are seeing DCT availability expand with the growth of gasoline direct injection in mainstream vehicle models, and in markets outside Europe. The common thread in all of these applications is the desire for full automation and seamless powerflow without compromising vehicle efficiency.
just-auto: I’ve heard that DCTs require a blend of additives which must be ‘intelligent’ and predictable. In other words, they have to provide reliable characteristics and adapt quickly to the specific friction demands required for the clutch operation to function efficiently. Is that correct? How important are those additives to make the DCT work?
Bob Blakely: A “wet” dual clutch is arguably the most demanding automotive application for a wet oil-bath friction material. The clutch is required to launch the vehicle from rest without shudder, and execute shock-free shifts in a few hundred milli-seconds. Friction coefficients must remain stable and predictable from cold starts to maximum operating temperature. The oil must endure rapid and extreme temperature excursions and transfer heat away from the clutch elements as quickly as possible. So, in summary… yes… the additive package for a dual clutch transmission fluid plays a critical role in achieving maximum performance from a DCT.
just-auto: From your perspective, how is DCT being promoted to the consumer? i.e. is it heralded as a comfort feature or is there more emphasis on its sporty and responsive performance?
Bob Blakely: When the target customers are still driving manual transmission vehicles, the value proposition for DCT is the convenience of full automation and the comfort of seamless powerflow, without compromising fuel efficiency, acceleration, or driving dynamics. This describes much of the European market, and most developing markets.
When the target customers have already accepted the on-cost of a conventional automatic transmission (or CVT) comfort and convenience are givens, there is greater emphasis on quick shifts, and the direct-connected feel drivers experience with DCT. In either instance, the sporty fun-to-drive attributes of the DCT capture the customers’ interest.
just-auto: In future, I guess we could see a variety of DCT systems. What will tomorrow’s DCT’s offer and on which segment? i.e. in terms of torque, driver comfort and performance?
Bob Blakely: Looking forward, we expect to see the greatest volume of DCTs spanning high volume global B, C, and D vehicle segments with torque capacity ranging from approximately 200 to 400 Nm. DCT is a natural complement to engine stop-start strategies, and mild HEV concepts. It is also evident that DCT has rapidly become the transmission of choice for serious performance vehicles in most size and price ranges. In these segments, engine torque is often much higher, maximum engine speeds up to 9000 RPM are not unusual, and acceleration that surpasses even an expertly driven manual transmission is now the norm.
The dual clutch transmission concept is a scalable technology, well suited to a wide range of vehicles and geographic markets. DCTs in production today range from high performance motorcycles to the fastest car in production today… Bugatti’s Veyron. At BorgWarner, we have seen interest in DCTs ranging from entry-level A and B segment cars for developing markets, to medium duty commercial vehicles up to 15 tonnes gross weight.