Powertrain developments cut fuel consumption and CO2 by 10%

CO2ncept-10% is based on a Porsche Cayenne with a V8 engine. In addition to tried and tested, optimised engine components, the vehicle is also equipped with several new powertrain and chassis components that help to significantly reduce the car's fuel consumption compared to existing production models. In the joint development project, Schaeffler was responsible for the design and testing of components, while Porsche managed system coordination and validation for the entire vehicle. The reductions in fuel consumption and CO2 emissions were verified theoretically through complex simulation calculations and practically via extensive bench testing at Porsche. The calculation standard used was the Standardised New European Driving Cycle (NEDC). The engine accounts for 5.8% of the optimised fuel consumption and associated CO2 emissions. Most of this (4.1%) comes from modification of the VarioCam Plus valve control system, by replacing hydraulic cam timers with electromechanical equivalents, as well as the use of optimised switching tappets on the intake side. An extra 1.7% reduction can be achieved through minimising frictional losses, by cross-system optimisation of valve train, belt drive and chain drive components. Double-row angular contact ball bearings that are installed in the front and rear axle differentials generated a further 1.1% in fuel savings. The bearings, which replaced the existing tapered roller bearings, reduce frictional resistance significantly when compared to conventional transmission systems. This reduction amounts to 35% in the front axle transmission and 42% in the rear axle transmission. Fuel consumption can also be reduced via the chassis. By replacing the hydraulic roll stabiliser with an electromechanically controlled equivalent and using smooth running wheel bearings, a 3.2% reduction in fuel consumption is achieved. "As is the case with cam timers, electrically-operated components make such an important contribution because they only require energy when they are operating," explained Dr Robert Plank, manager of corporate engineering at Schaeffler. "In hydraulically-controlled systems, the pumps need to maintain pressure at all times, resulting in much higher energy requirements." "This project is a good example of successful cooperation between an automobile manufacturer and supplier. This cooperation reduces development times, avoids extensive redundancies and makes an important contribution to competitive ability."