New thermoset polymer-based camshaft module lightens automotive engine weight
As an alternative to aluminum, a research team from the Fraunhofer Institute in Germany has successfully manufacturing a camshaft module from fibre-reinforced thermoset polymers.
Plastics have been hugely beneficial in allowing carmakers to lightweight vehicle parts for improved mileage and reduced CO2 emissions, with one exception: camshaft modules, which are a key component of powertrains, are still being made from aluminum.
Now a research team from Germany’s Fraunhofer Institute for Chemical Technology ICT, in collaboration with their partners, has succeeded in manufacturing a camshaft module from fibre-reinforced thermoset polymers. This lightweight design element helps lower engine weight and reduces assembly costs, and is currently available as a functional demonstrator.
Camshafts ensure that the charge-cycle valves in internal combustion engines are opened and closed reliably and precisely. These valves are located in the camshaft module, the standard material for which is – as mentioned – still aluminum metal. But automotive manufacturers and suppliers are putting great effort into producing powertrains and their components in lightweight design, and the researchers at Fraunhofer ICT are supporting these efforts. The team’s lightweight camshaft module was realized in cooperation with the MAHLE Group and associated partners Daimler AG, SBHPP/Vyncolit NV, and Georges Pernoud. The German Federal Ministry for Economic Affairs and Energy has been funding the project.
When it comes to the choice of the right polymer, the project partners opted for high-strength, fibre-reinforced thermoset polymers, as they are well able to withstand high temperatures and mechanical and chemical stresses such as those caused by synthetic motor oils and coolants, for instance. “We contribute the know-how regarding how to design the component geometries to suit the material and the process so that they satisfy all requirements,” said Thomas Sorg, a researcher at Fraunhofer ICT. “The camshaft module is located in the cylinder head, so normally in the upper installation space of the powertrain. Here, it makes particular sense to reduce weight, since doing so also contributes to lowering the vehicle’s center of gravity.”
Unlike castings made from aluminum require, fibre-reinforced thermoset polymers allow a near-net-shape manufacturing process that requires comparatively little reworking, leading reduced production cost. Also, at up to 500,000 units, the service life of thermoset polymer injection molds is significantly higher than that of aluminum high-pressure die cast molds. Furthermore, plastics reinforced with a high fibre content have a much lower CO2footprint compared with aluminum, since this light metal is very energy-intensive to manufacture.
Another advantage of using thermoset polymers is that they have good damping characteristics, which can eliminate rattling and other noise emissions.
And the camshaft module features a monolithic design with integrated bearings, which means it’s manufactured in one piece, which reduces assembly time in the engine manufacturing plant.
During initial tests on the engine test stand, the Fraunhofer ICT researchers observed positive operating performance, and weight savings were demonstrated compared with the aluminum reference part. “We can the produce camshaft modules made of thermoset polymer material much more easily than their counterparts made of light metal, and we can even do it economically in an injection molding process,” Sorg said. “Although the stiffness of the thermoset polymer is only a quarter of that of aluminum, design measures enabled us to adhere to the maximum allowable deformation.”
After 600 hours of testing on the engine test stand, the lightweight design element demonstrated near-perfect functionality in a state-of-the-art internal combustion engine. With the aid of the planned fuel injection tests, the project partners want to prove the functionality and the NVH characteristics taking the gas forces of the combustion process into account.