In an internal combustion engine, the camshaft – or in some cases, camshafts - ensure that the intake and exhaust valves in the camshaft module open and close in synchrony with the movements of the pistons. They are critical to the operation of an engine and can have a significant effect on performance. Today, camshaft modules are mainly made of aluminium.
Yet, with lower, more stringent CO2 emission targets looming, automotive manufacturers and suppliers are putting great effort into producing powertrains and components in lightweight design.
In search of an alternative, a research team at the Fraunhofer Institute for Chemical Technology ICT partnered with a number of industrial players on the development of a camshaft module made of fibre-reinforced thermoset polymers.
High-strength, fibre-reinforced thermoset polymers were selected, as they are well able to withstand high temperatures and mechanical and chemical stresses such as those caused by, among others, synthetic motor oils and coolants.
Lighter than metal, the design lowers engine weight and reduces production and assembly costs. Castings made from aluminium require extensive reworking after casting. Not only do fibre-reinforced thermoset polymers allow for near-net-shape manufacturing, which requires little reworking, at up to 500,000 units, the service life of thermoset polymer injection moulds is significantly higher than that of aluminium high-pressure die-cast moulds. Furthermore, fibre-reinforced plastics have a much lower CO2 footprint compared with aluminium, which is very energy-intensive to manufacture.
In addition, said Thomas Sorg, a researcher at Fraunhofer ICT, polymers have good damping characteristics. “This makes it very easy to optimize the acoustic performance of the camshaft module,” says Sorg. The camshaft module features a monolithic design with integrated bearings – in other words, it is manufactured in one piece, thus reducing assembly time in the engine manufacturing plant. Car manufacturers will receive a pre-assembled module from their supplier and can mount it on the engine with just a few simple mounting operations.
The module is currently available as a functional demonstrator. It has undergone 600 hours of testing on the engine test stand during which it demonstrated ‘flawless functionality’. As the next step, the project partners - MAHLE Group and associated partners Daimler AG, SBHPP/Vyncolit NV and Georges Pernoud - with the aid of the planned fuel injection tests, will seek to prove the functionality and the NVH characteristics, taking the gas forces of the combustion process into account.
This project received funding from the German Federal Ministry for Economic Affairs and Energy (BMWi).