Overview of Measurement Technology for Valve Lift and Rotation on Motored and Fired Engines

In the last decades the operational requirements to control the gas exchange of an internal combustion engine increased immensely. The gas exchange is mainly controlled by the valve train system affecting the combustion behavior and power output of the engine. The necessary valve lift curve must be ensured within the whole operation range of the engine. Moreover, a minimum friction has to be achieved. On the one hand engine speeds and loads of the valve train components have increased and the weights of the components have decreased, on the other hand the demands regarding durability increased as well. The engine development department has tried to find out optimization potentials of valve train dynamics to get along with these challenges. During an engine development process analysis tools together with measurements of the dynamic valve train behavior on motored cylinder heads using Laser Doppler Vibrometry are applied. However, influences caused by the gas exchange process, thermal effects and additional issues of a complete engine under fired conditions are neglected with this approach. Therefore the differences between the ideal and real valve opening and closing together with real valve timing as well as detailed information about the gas exchange and the dynamic behavior of the valves need to be assessed. Taking care of these mentioned issues, dynamic valve train investigations on a fired engine using Magneto-Resistive (MR)-sensors have to be performed.