On the road to optimum total system solutions

2016-01-11 | 000-006-540 DE-EN

SCHAEFFLER AG, DETROIT

Total efficiency in the drivetrain: Interactive engines and transmissions

On the road to optimum total system solutions

While there are significant differences in the mobility needs around the world, vehicle transmissions have a decisive role to play in terms of the energy efficiency and environmental sustainability of mobility in all regions of the world. The development of energy efficient transmission concepts will therefore become increasingly important in the future. Continuous increases in efficiency and high levels of electrification will define the technological path of the drive architecture. Transmissions will therefore have an important part to play in the future of the engine and the overall efficiency of the drivetrain.

Interdisciplinary developmental work is the key to success

Finding the optimum combination of the individual components is a critical factor in reducing consumption. In this respect, Schaeffler offers the automotive industry benefits that are not available from any other supplier. A key to Schaeffler's success is its interdisciplinary developmental work where expertise from different specialist areas is brought together. The internal combustion engine, the transmission and the electrical components are regarded as a single unit in order to produce joint solutions.

One example is the close coordination of the development work involved in cylinder deactivation strategies in the internal combustion engine, the effects on the timing drive and the required control of the modified torsional vibration excitations using optimized damper systems in the transmission, states Klaus Cierocki, Vice President, Engine Systems at Schaeffler.

The comprehensive product portfolio of solutions in and around the engine, transmission and chassis leads to synergistic development of customer-oriented products.

Optimizing the internal combustion engine

Measures to optimize the combustion engine are a particular point of focus. Apart from reducing friction - through a highly efficient coating process in the valve train or by replacing plain bearings with rolling bearings or through efficient tensioning and decoupling systems in the auxiliary drive assembly - Schaeffler is also working on the introduction of turbochargers supported by rolling bearings, increasing thermodynamic efficiency and a diverse range of technical solutions. For example:

Thermal management: An important element is the Thermal Management Module (TMM) which accurately controls the temperature balance in the engine in an energy efficient way, and allows the ideal temperature window for the engine and the transmission to be reached rapidly. This unit can also provide parallel control of the temperature balance in hybrid components and batteries. The cold running phase can be shortened considerably by blocking off the engines cooling jacket while individual components can be run hotter than would otherwise be possible with thermostatic control. The module therefore also has a positive effect on the operating life of drivetrain components. A further benefit is being able to reduce the engine temperature while under full load, thus reducing the tendency towards knocking and full load enrichment.

All of this makes this module, which can be adapted to suit customer requirements, a key element in the reduction of fuel consumption and CO2 emissions. This technology has been successfully introduced in the European and Asian markets and will be used in volume production in the North American market in 2017. The most recent generation of the TMM is a modular design and is more compact and has additional functions, such as intelligent smart actuator technology. Integrating control into the module takes some of the strain off the engine control system and leads to optimum coordination of all operating points. As part of the company's In the Region, for the Region strategy, Schaeffler will also manufacture the TMM in continental America in the future.

Variable valve train: From phasing units and switchable finger followers through to the fully-variable valve train system UniAir, Schaeffler offers a comprehensive range of products for variability in the valve train. Tailor-made operating strategies, such as cylinder deactivation or special valve stroke curves, can be produced to suit customer requirements. The start of volume production of the UniAir technology in 2009 marked the beginning of a new era in valve control systems. At the same time, Schaeffler set a new technological standard for environmentally-friendly and dynamic engines. To date, over one million UniAir systems have been produced in North America and this will exceed to two million globally in 2016. The fully-variable electrohydraulic valve train system UniAir controls the engine valves and allows almost any valve stroke to be realized. It is possible to achieve considerable reductions in consumption and emissions through this technology, as well as a significant improvement in torque curves.

Partially and fully-variable valve train systems also allow individual cylinders to be deactivated while driving. So, for example, the fuel consumption of an eight-cylinder vehicle could be reduced by temporarily running on four cylinders. Hydraulically switchable valve train components are usually used to deactivate specific cylinders. UniAir provides an extended range of options for matching engine operation to specific situations or requirements, such as rolling cylinder deactivation where each cylinder can be switched off in turn. A key advantage is that the deactivated cylinder does not cool down, allowing the system to reactivate more quickly after a cold start.

Electromechanical camshaft phasing unit: Another approach is replacing hydraulic systems with electromechanical systems. Schaefflers

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