Dynamical behaviour of a torsional system with parametric and external excitations

Abstract The dynamic behaviour of a torsional system with a one-cylinder, reciprocating compressor driven by an asynchronous motor is studied using a two degrees-of-freedom (2 DOF) lumped-parameter theoretical model. The model takes into account the variability of the mass moment of inertia of the crank mechanism and the presence of pressure forces loading the compressor piston. The influence of the ratio of the variable to the constant part of inertia in the crank mechanism and the effect of the load torque due to pressure forces acting on the piston are examined in relation to system dynamic behaviour. Experimental data, obtained with the adoption of a suitable rig, show that the theoretical indications can be considered reliable, despite the approximation that was given to the mathematical model as far as the treatment of the damping and the absence of clearances were concerned.