LuK s CVT chain provides continuously variable driving comfort

Subaru Combines a Continuously Variable Automatic Transmission Featuring Components from Schaeffler's LuK Brand with a Flat Diesel Engine in Volume Production for the First Time

LuK's CVT chain provides continuously variable driving comfort

The CVT (Continuously Variable Transmission) represents continuous driving with no interruption to the tractive force and this is an idea that has inspired automobile designers and customers for many years. The combination of a continuously variable automatic transmission, equipped with LuK's multi-link chain, and a flat diesel engine that is featured in Subaru's Outback 2.0D Lineartronic is a new entry to the market.

LuK GmbH & Co. KG, the Schaeffler Group's specialist for systems and components for vehicle drive trains, has been a development partner to SUBARU for ten years. This collaboration produced a highly efficient all-wheel drive CVT that was presented for the first time at the 2009 New York International Autoshow under the name LineartronicTM . Even during the initial stages of development, the chain variator (see informational graphic) was able to reliably cover engines with up to 400 Nm of torque and outputs of 220 kW/300 HP while maintaining compact dimensions and a wide ratio spread. There was therefore nothing to stop it being used with higher-performance and turbocharged gasoline engines and even with SUBARUs flat diesel engine.

The CVT chain and the guide rails are supplied by Schaeffler's LuK brand. In 2013, approximately 1.2 million CVT chains for three different international vehicle manufacturers, together with the corresponding number of guide rail sets, will come off the production line at Schaeffler's manufacturing location in B hl. We contributed to the success of the project in many areas with our expertise in complete CVT systems , explains Andreas Englisch, CVT Product Line Manager at LuK in B hl. The comprehensive development and testing process includes package tests, variator design, dynamics simulations, and comprehensive tests with regard to function, acoustics, and operating life.

Since they were first launched on the market for high-torque applications (in 1999), the outstanding features of LuKs CVT components have gained a substantial reputation among specialists: In addition to suitability for high outputs and torques and high power density with compact transmission dimensions the focus is also on high efficiency. Consequently, LuK's multi-link chain is now being used in high-volume production by three international vehicle manufacturers in Europe and Asia.

The markets promise potential for growth: Although largely unnoticed in Europe, worldwide CVT production has risen to a current level of almost seven million units per year, which corresponds to 12.5 percent of all vehicles with automatic transmissions. This growth is focused primarily on the Asia Pacific region and Japan in particular, where 36 percent of all new passenger vehicles are already equipped with a CVT. From a global perspective, the CVT has an overall market share of nine percent. How this development will continue depends on factors such as local conditions and preferences. As a supplier to the automotive industry, Schaeffler is convinced that the different transmission concepts that will exist in the future will become increasingly similar to each other in terms of their characteristics.

The increasing worldwide requirements with regard to emissions and fuel consumption make a very strong case for the use of CVTs: The continuous adjustment of the gear ratio without interrupting the tractive force means that the engine can always be operated in the section of the data map that is most favorable in terms of fuel consumption. The fuel consumption figures that this produces are on the same level as those of manual transmissions operated in the ideal manner. Among other things, Schaeffler also relies on modular product strategies in order to provide a customized response to the different requirements of the worlds various markets. The CVT, for example, is a very convenient solution for high-density traffic with widely varying driving speeds, which is a normal occurrence in Japan today. Even the NAFTA region, where gentle starting is still an important issue for customers, is an area where the CVT can be successful , explains Dr. Hartmut Faust, Senior Vice President R&D of Schaeffler's Transmissions Business Division.

Maximum ratio spreads can be achieved by using components from Schaeffler's LuK brand. This also makes these components an ideal addition to Schaeffler's comprehensive product portfolio for implementing the trend for downsizing and downspeeding in engine construction. Hybrid concepts can also be optimally combined with CVT components.

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