Dynamic Characteristics of Viscous-Friction Dampers by Simultaneous Vibration Displacement Measurement at Two Points

The dynamic characteristics of conventional viscous-friction dampers are investigated in this paper by adopting simultaneous vibration measurement method at two points. The vibration displacements of the damper casing and the inertia ring can be simultaneously measured in this method. It has become possible that the more detailed dynamic characteristics of the viscous-friction damper can be grasped by the method. Especially, it is an effective method to grasp the behaviors of the inertia ring and the damper casing for clarifying the effect of the silicone fluid on the torsional vibration of crankshaft system. The damper casing was made of acrylic resin in order to measure the behavior of the inertia ring on engine operation. It is possible to measure the torsional vibration displacements waveforms by the optical signals from pulse tapes stuck in both peripheral sides of the damper casing and the inertia ring. And, the dynamic characteristics of the silicone fluid were investigated by changing the viscosity of the silicone fluid and the clearance between the damper casing and the inertia ring. As the experimental results, it is shown in detail that the torsional vibration of the engine crankshaft system is greatly influenced by the peripheral gap, the lateral gap and the viscosity of silicone oil of the viscous damper, and that the values of the peripheral and lateral gaps between the outside of the annular seismic - mass and the inside of the damper casing given by the widely-adopted BICERA's empirical formula are not always optimum on the every viscosity of the filled silicone fluid of the viscous damper.