Influence of cylinder pressure on the balancing of a rotary compressor

The investigation presented concerns the balancing procedure of a rotary refrigerant compressor subjected to fairly well-known eccentric masses and to a cylinder pressure force. Particular attention is paid to the influence of pressure force on the response of the compressor. The cylinder pressure force is expanded in a Fourier series for evaluating the bearing characteristics, establishing the balancing and predicting the response of the entire compressor. Rotor dynamics, the finite element and influence coefficient methods are used in order to reduce the vibration levels of the rotor and stator parts of the compressor. The prediction focuses in particular on the orbits at the top and bottom of the housing of an industrial compressor. It demonstrates that cylinder pressure plays a negligible role in the case of the rotary machine presented here, but must be taken into account when high pressure and weak bearing characteristics are combined.