Ventilfedern führen im Motorbetrieb außer den Längsbewegungen auch Drehbewegungen aus, die zu Verschleiß führen. Das Phänomen der Drehbewegungen ist bisher ungeklärt, weshalb deren Ursachen und die Möglichkeiten zu ihrer Beeinflussung ermittelt werden sollten. Es fanden umfangreiche experimentelle Untersuchungen an einem Versuchsstand statt, wobei die Drehbewegungen von Feder und oberem Federteller als Funktion von Nockenwellendrehzahl und Federvorspannung erfasst wurden. Dieses Phänomen wurde analytisch mit einem mathematischen Modell sowie mit Simulationen mit der Software SimulationX® und der Mehrkörpersimulation RecurDyn® untersucht. Bei diesen Drehbewegungen handelt es sich um sehr komplexe Bewegungen, deren Ursache Resonanzen sind. Sie hängen hauptsächlich von der Federwinderichtung, der Federvorspannung, der Nockenfunktion und der Nockenwellendrehzahl ab. Die Einflussmöglichkeiten auf diese Bewegungen sind tabellarisch zusammengefasst.
During engine operation, valve springs carry out, apart from functional longitudinal movements, also rotating movements which lead to wear at the spring load surfaces and the neighbouring components. However the rotating movements are deliberate, as they are transferred to the valve tappet with the valve retainer. This keeps the valve seats clean and the thermal load is distributed more uniformly over their circumference. Until now the phenomenon of rotating movements has not been clarified, this is why their causes and the possibilities to influence them had to be determined. A first step to clarify the problem was to determine the twisting of the spring ends one to the other at static deflecting. Moreover extensive experimental analyses were carried out at a test station, where the rotating movements of spring and valve tappet resp. upper spring retainer were recorded as a function of camshaft speed and spring preload. A mathematic model provides first theoretical knowledge about the development of the rotating movements. Further analyses were carried out with the SimulationX® program. The used principle model is composed of two parallel spring/mass systems of which one system oscillates in a linear and the other in a rotating manner. As the spring mass is distributed continuously over the spring, the best results were expected from a multi-body simulation which was carried out with the RecurDyn® program. The tests showed that the rotating movements mainly depend on the spring coiling installation, spring preload, cam function and camshaft speed. High-speed records showed that these movements are very complex and that resonances are the cause of the rotating movements. For the development of the rotating movements a release of the spring ends is necessary, which is caused by the harmonic oscillations of the cam function situated near the longitudi- nal natural frequencies of the spring. Moreover the ratio between the harmonic oscillations and the rotating natural frequencies influences the rotating movements. The mathematic model shows that there might be a direction reversal if the resonant frequency is exceeded. The possibilities to influence the rotating movements of spring and valve tappet are summarized in the remarks for the Des.Engrs. with regard to design and optimization of valve drives. However any precalculation will need further analyses.