The lightweight balancer shaft with rolling bearing supports has also received the PACE Award and the Steel Innovation Prize.
The rolling bearing supports reduce friction and enable a new balancer shaft design with an optimized mass.
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Schaeffler Group USA Inc.
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2012-01-09 | 000-003-292 DE-EN
SCHAEFFLER AG, HERZOGENAURACH/DETROIT
The supplier to the mobility industry and rolling bearing specialist Schaeffler is also offering a good example for the successful use of rolling bearings in engine construction with the lightweight balancer shaft with rolling bearing supports. These rolling bearing supports with reduced friction significantly improve the energy efficiency compared to the plain bearings that were previously used. In the case of the lightweight balancer shaft with rolling bearing supports, the power consumed internally in a four-cylinder diesel engine already in volume production is reduced, for example, by up to 1.5 kW (2.0 horsepower). The rolling bearing supports also reduce the requirement for oil cooling and make the previously obligatory pressure lubrication no longer necessary. These features in conjunction with the superior emergency running characteristics make lightweight balancer shafts with rolling bearing supports particularly suitable for engines with start-stop systems. The rolling bearing supports also enable a new balancer shaft design with an optimized mass that is reduced by around one third. This means the two balancer shafts mounted in an engine, which run at twice crankshaft speed due to the design, reduce engine weight alone by more than a kilogram. The filigree design also minimizes the shaft’s rotational inertia and, thus, in turn reduces the driving forces required.
This means that lightweight balancer shafts with rolling bearing supports also make a contribution to reducing fuel consumption and CO2 emissions as well as increasing smoothness. They are in increasing demand due to the trends for downsizing and downspeeding of engines.
The turbocharger is an important component for downsizing high-performance gasoline engines and for high-torque diesel engines. The performance of rolling bearing solutions in this application is no less impressive. In specific terms, the rolling bearing supports enable increased torque, improved response as well as reduced consumption and emissions.
The significantly reduced frictional resistance of a turbocharger with rolling bearing supports compared to a component with plain bearing supports results in higher bearing shaft speeds in the low and partial load ranges. This leads to significantly increased acceleration of the turbocharger in the case of an increased load, and the higher turbocharger speed improves the response of the turbocharger and reduces so-called “turbo lag”. The fresh air supply is optimized and emissions are significantly reduced. The raw emissions in the low and partial load ranges are reduced by a factor of two compared with comparable engines with turbochargers with plain bearing supports. The optimization potential for reducing fuel consumption and CO2 emissions which has been verified in the NEDC* is up to four percent.
Turbochargers with rolling bearing supports are currently used in motor sport and also on the road in passenger cars and trucks. Accordingly, Schaeffler offers a wide range of turbocharger solutions with rolling bearings, which are available tailormade for different shaft diameters from 6 to 24 millimeters and come completely assembled in cartridge form. The cartridge design of this product, which is used in a thermally stressed position, ensures the highest-possible precision. This benefits both the quality and ensures a low noise level. “Turbochargers that have been optimized by means of rolling bearing supports can demonstrate their strengths particularly impressively if they are used as part of downsizing measures“, says Dr. Peter Solfrank, who is responsible at Schaeffler for the product group rolling bearings and balancer shafts in engines. “A turbocharger with rolling bearing supports can be used to perform the tasks otherwise performed by two turbochargers that are combined with each other in order to ensure instantaneous response and a high maximum throughput.”
Amongst the additional requirements for modern internal combustion engines is that their design must be suitable for use in start-stop systems. Rolling bearing supports also offer significant advantages due to the principle that they prevent mixed friction conditions. Camshafts and gears in the timing drive are therefore amongst the further applications for rolling bearings in engines. Optimized frictional resistance, the ability to compensate for increased radial loads and tilting moments, optimized lubrication requirements and an axial guidance facility are the significant advantages of rolling bearing solutions.
*NEDC = New European Driving Cycle