A Groundbreaking Component for Future-Generation Engines

UniAir/MultiAir: Schaeffler Group manufactures the world's first fully variable hydraulic valve control system

The market launch of the world's first fully variable hydraulic valve control system once again substantiates the Schaeffler Group's reputation as an innovation leader and problem solver for highly demanding technical challenges.

Developed in collaboration between Fiat Powertrain and the Schaeffler Group and manufactured by Schaeffler, the UniAir valve control system will make its debut in the Alfa MiTo 1.4 MultiAir. This compact Alfa Romeo is the first vehicle within the Fiat Group to be equipped with the new innovative technology. Combined with the downsizing options, the fully variable valve control system enables reductions in fuel consumption and CO2 emissions by up to 25 percent. The improvements in starting, part load and acceleration behavior are especially conspicuous. During the warm-up phase, for instance, hydrocarbon emissions (HC) are up to 40 percent lower and nitrogen oxide emissions (NOx) even drop by up to 60 percent. And at the same time, UniAir also provides a higher level of driving pleasure - through more power, higher torques and optimized engine response.

The fully variable valve control system is an appropriate response to the ever more stringent regulations concerning emission reduction and lower fuel consumption. The system offers an attractive option for making existing engine series fit for the future and it is excellently suited for implementing downsizing solutions. Here Fiat is a trend setter: The fully variable valve train system is used both in the four-cylinder FIRE engine family and in the small-volume two-cylinder engines of the future. In addition to gasoline engines, it will also be available for diesel engine applications.

Developed for series production by the Schaeffler Group, the innovative UniAir-System is called MultiAir by Fiat. This name follows the style of the MultiJet CommonRail direct diesel injection system, which was also initiated by Fiat. UniAir/MultiAir is also based on an invention by the Centro Ricerche Fiat (CRF). With the Schaeffler Group, Fiat has found just the right development partner for this sophisticated and highly efficient valve control system. The takeover of the license in 2001 marked the start of a successful development through to series production maturity and market launch. In 2003, the first functioning prototype left the development center in Herzogenaurach. Further prototype vehicles were manufactured two years later. The "design freeze", in other words the specification of the final series design, took place in 2007 and the construction of manufacturing facilities for series production at the Schaeffler Group locations commenced in 2008. Since May 2009, the MultiAir system has been developed in series for Fiat, or Alfa Romeo. "The development of the fully variable valve control system to production standard has involved complex efforts in the fields of mechanics, hydraulics and valve control software," explains Michael Haas, Director Advanced Engineering and Business Development within Schaeffler Group Automotive's Engine Systems unit. These tasks were tackled by a development team consisting of about 45 specialists.

UniAir is a cam-actuated, electro-hydraulic valve train system. The fully variable valve control can be used both in gasoline and in diesel engines and is supplied via the existing engine oil circulation system. UniAir allows throttle-free, continuously variable, software-based load control across the entire engine map to be implemented with gasoline engines. With diesel engines, regulation of the combustion chamber temperature is feasible thanks to the precise control of exhaust gas recirculation rates. At the same time, the effective compression ratio in the cylinder can be varied and a homogenous combustion ensured.

In addition, for the first time UniAir/MultiAir allows not only variations in the valve stroke, but also the opening and closing of valves several times during one cycle, at different points in time. Thus UniAir significantly expands the potential of former variable valve train mechanisms. "The UniAir system is the beginning of a new era in valve trains and thus in technology producing engines that are eco-friendly and dynamic at the same time," says Dr. Peter Pleus, Executive Vice President of Schaeffler Group Automotive.

About the Schaeffler Group INA is the abbreviation for "Industrie-Nadellager" - the German term for 'industrial needle roller bearings' - and goes back to an invention by Dr. Georg Schaeffler in 1949. His development of the needle roller and cage assembly - a groundbreaking innovation - helps the needle roller bearing achieve its industrial breakthrough. Still today, Georg Schaeffler's inventive spirit and will to success are firm constituents of the INA culture worldwide. INA boasts unrivaled expertise in the non-cutting manufacture of precision products. This helps to bring about efficient customized solutions at an excellent price-performance ratio. The automotive industry uses INA-branded products in engine, transmission and chassis applications.

More from Materials

All Topics