Impact Analysis of the Aging Silicone Oil in the Damper on the Torsional Vibration of the Crankshaft of the Heavy-Duty Vehicle Diesel Engine

The silicone-oil damper of the diesel engine has significant effects on reducing the torsional vibration and the torsional stress of the crankshaft. The nature to maintain viscosity of the silicone oil is an important indicator when we evaluate the reliability of a silicone-oil damper. With a heavy-duty vehicle diesel engine which meets China 6 emission standards as an object of research, this paper used AVL EXCITE to establish the torsional numerical model of the crankshaft which considers coupling effect of the non-linear stiffness and the damping of the silicon-oil damper, and discussed the impacts of the silicon oil in different viscosities on the amplitude of the torsional vibration and the dynamical tangential stress. The numerical results were also compared with the measurements in the dynamical durability test in which applying the time variable. The results indicate the measurements in which the diesel engine run 953 h turn out to be close to the simulation and demonstrate the accuracy of the dynamical numerical model. If the viscosity of the silicone oil reduces not more than 40%, its impacts on the torsional vibration and the torsional stress of the crankshaft are limited. However, with the viscosity increasing to 70%, the 6th-order vibration amplitude approach to the requirement limit, so that should be taken into consideration. Objectively speaking, the changes of the silicone oil viscosity will not have great impacts on the damper under normal use. For optimal performance, there should be the enhanced durability to the silicone oil in the damper and should take some effective measures to avoid the overquick decrease of the silicone oil viscosity.