Method of selection of optimal damping coefficients for torsional vibration dampers of crankshafts of automobile and tractor engines

Abstract

We have analyzed of free oscillations of the reduced torsional system of the crankshaft of a six-cylinder piston engine with the rubber or liquid damper. When we installed the torsional vibration damper on the crankshaft, than it changes the frequency of free oscillations. For the rubber damper it is changing the freguency of free oscillations while we is added mass of the body of the damper and the coefficient of rigidity of the rubber layer and the moment of inertia of the flywheel, which is added to the moment of inertia .the first mass (the toe of the crankshaft). For liquid torsional vibration damper, the flywheel which has no direct connection with the toe of the crankshaft, the calculation of free oscillations is half the moment of inertia of the flywheel, fluid damper end to the moment of inertia of the sock. We consider the procedure for selecting the optimal damping coefficients of dampers, and, namely, the moments of inertia of the flywheel damper and damping coefficients. When selecting the amplitudes of the free oscillations of the mass of the damper flywheel and the crankshaft wear (or damper body) in a complex form and substituting derivatives of these quantities in the differential equations of free oscillations, the functions that can be taken as optimization parameters are obtained. In this case, the amplitude of the torsional vibrations of the crankshaft wear is reduced as much as possible with the optimal damping or the maximum of the energy dissipated in the damper. For internal friction dampers, a rubber layer stiffness coefficient is added in addition to the specified parameters. It is shown that these selected parameters also affect the circular frequency of free oscillations, so their selection should be carried out taking into account this circumstance.