Verbesserung der Floating-Liner Methode zur Messung der Kolbengruppenreibung durch Einsatz doppelschrägverzahnter Zahnriemen

The mechanical losses of internal combustion engines depend to a large extent on the frictional forces occurring within the piston group. Since the piston group represents the most complex tribological system in the engine, a high level of understanding is necessary in order to optimise the components. For this purpose, it is necessary to measure the occurring friction forces directly and with crank angle resolution. One possibility for this is the floating-liner method, in which the liner in single-cylinder research engines is mounted axially floating on load cells. A limitation of this measuring method is the high susceptibility to disturbances, especially from vibrations. Some of these vibrations originate from the control drive to the cylinder head and the mass balancing typically installed in single-cylinder engines. Belt drives with continuous tooth engagement, such as double helical belts, can in theory reduce the vibrations of these belt systems. For this reason, two belt drives of a floating liner research engine were equipped with such double helical belts. The continuous tooth engagement reduces the average vibration amplitude of the occurring vibrations of the force signal by up to 22% depending on the engine speed. A vibration analysis using Campbell diagrams also shows that, in contrast to the straight-toothed belt system, no more excitations occur due to the installed pulleys. In addition, the amplitude of the vibration excitation of the force measurement is reduced. All in all, double helical belt drives thus offer a simple way to significantly reduce the disturbance variables in systems that are susceptible to vibrations, such as the research engines for friction force measurement.