Three suppliers are developing dual-clutch systems to compete with early leader BorgWarner and meet the expected strong European demand for the technology.
Clutch suppliers LuK GmbH, Valeo and ZF Sachs are working on dual dry-clutch systems. ZF Sachs is working on a dual-dry and a dual-wet clutch.
New systems that provide a choice either leaving the transmission as an automatic requiring no manual shifting or allowing manual shifting of the automatic without a clutch have become a given in the industry.
BorgWarner's variation on the theme is called DualTronic. It allows a manual transmission to provide the convenience of an automatic with the fuel efficiency of a manual.
The supplier's dual wet-clutch system eliminates the "torque-interrupt" feeling when a manual transmission shifts gears. BorgWarner claims the technology lowers emissions and fuel usage up to 15 percent, depending on the application.
DualTronic made its debut in 2003 in the Audi TT 3.2 and the Volkswagen Golf R32. It also is on the limited edition 2004 Bugatti 16.4 Veyron.
Goal: 18% in Europe by 2010
Only 25 percent of cars and SUVs in Europe have automatic transmissions compared with 90 percent in the United States.
BorgWarner expects the clutch systems to be fitted on up to 18 percent of all cars sold in Europe by 2010.
The increase will come partly at the expense of conventional torque converter-driven planetary transmissions but mostly to replace manuals.
BorgWarner's competitors among the major European clutch suppliers are trying to catch the market front-runner.
Peter Gutzmer, CEO of LuK GmbH, a leading clutch manufacturer and transmission supplier, says there may be fuel efficiency gains of 3 percent to 5 percent from a shift from wet-clutch technology to dry-clutch technology.
Cutting weight, cost
The dual dry-clutch approach eliminates the need for hydraulic pumps for the clutch, which Gutzmer says reduces weight and decreases cost.
"You can use the system to create damping by software control," and avoid a dual-mass flywheel or dampers, Gutzmer says.
LuK showed its concept in September at the Equip Auto Show in Paris. Gutzmer says LuK is still determining how to manufacture the technology efficiently.
Gutzmer expects that the second-generation dual-clutch system will be ready for production in about two years.
Valeo's Didier Lexa, director of advanced product research at the French company's transmission business, said wet-clutch technologies are best suited for high-torque engines.
The downside is that Lexa sees a potential cost increase over automatic transmissions of more than 10 percent.
Valeo is working to bring cost down and stabilize quality, he said.
ZF Sachs will pursue both wet- and dry-clutch technologies until the automakers decide which they prefer, says Peter Ottenbruch, the director of ZF Sachs' clutch business. When they do, ZF Sachs thinks an introduction in 2006 is possible.
Ottenbruch also thinks that a 20 percent share of medium-sized cars is possible if most consumers accept dual-clutch technology.
Automated manual transmissions attracted attention in Europe in the 1990s, but were never accepted by consumers.
Dual-clutch transmissions have to compete with new-generation automated manual transmissions, continuously variable transmissions, and new six- and seven-speed automatic gearboxes.