New materials win awards for Daimler

Mercedes-Benz, part of Daimler AG, has won two awards for the development of new materials in two different applications: pistons and struts.

Mercedes-Benz is claiming between 2 and 4 per cent improved fuel consumption and CO₂ emissions from its passenger-car diesel engines resulting from "new" pistons. These are, according to Mercedes-Benz, the first engines worldwide to be equipped with "innovative" steel pistons in conjunction with a lightweight aluminium cylinder block.

The reduction in fuel consumption is even more pronounced at lower and mid-range engine speeds, it seems. These ranges play an important part in everyday driving. For this Mercedes-Benz received a recent MATERIALICA "Best of Award" for the innovative steel pistons in the category "CO₂ Efficiency".

At first glance, the combination of aluminium cylinders and steel pistons seems problematic: steel expands less than aluminium when heated; it conducts less heat and is heavier.

These are the reasons why aluminium pistons have been used to date. Yet the Stuttgart engine designers seem to have succeeded in turning these apparent disadvantages into advantages.

For example, the lower expansion of steel as operating temperatures rise ensures increasing clearance between the piston and the aluminium housing. This reduces friction by 40 to 50 per cent, according to the engineers. At the same time, the fact that steel is stronger than aluminium allows compact, lightweight pistons that offer additional strength reserves.

Finally, the company claims the lower thermal conductivity of steel leads to increased component temperatures, thus improving the thermodynamic efficiency with higher ignition performance and reduced burn time. The company however declines to reveal more details of the "new" pistons.

      

                                                     CFRP struts

Mercedes-Benz won a second award for high-strength CFRP struts that are of lightweight construction designed for mass production

All vehicle designers aim to produce a vehicle body that is as stiff as possible, since having a stiff body shell as a basis allows dynamic handling and also helps to minimise NVH – noise, vibration and harshness. Fibre composites, particularly those that include carbon fibres, are ideal for ensuring maximum stiffness with minimum weight. Until now high costs have prevented their widespread use in vehicles.

However, a Mercedes-Benz innovation claims to have changed all this. This innovation allows automatic, low-waste and therefore, cost-effective production of ultra-stiff and extremely light CFRP struts, making mass production possible.

Mercedes-Benz received a MATERIALICA "Gold Awards" for this innovation in the category "Material".

The core of this innovation is the combination of several components: carbon-fibre layers provide maximum stiffness and additional outer layers, applied at different angles ensure high pressure resistance. A third component developed by Mercedes-Benz relate to the innovative force elements which transfer all loads safely to the CFRP-struts.

The results are struts that are 70 per cent lighter than standard steel struts. The lighter weight also helps reduce fuel consumption. The CO₂ break-even point (i.e. the distance the more fuel-efficient vehicle has to travel before the increased amount of CO₂ used to produce the carbon-fibre components is saved) is only approximately 50,000km.

Furthermore, this Mercedes-Benz innovation allows a production process for more than 300,000 vehicles a year.

The award ceremony took place during the recent MATERIALICA trade fair in Munich, Germany.