Introduction to Hermetic Reciprocating compressor

Hermetic-Reciprocating compressors typically consist of a crankshaft having an eccentric portion coupled to a compression mechanism, which is driven when the crankshaft rotates. The compression mechanism comprises a piston sliding in a cylinder; the piston operatively coupled to the eccentric portion of the rotating crankshaft by means of a connecting rod, whereby the orbiting motion of the eccentric about the axis of rotation of the crankshaft imparts reciprocating motion to the piston. Due to the dynamic imbalance of the operating compression mechanism, counter-balance weights are often attached to the crankshaft, in some cases directly attached to the eccentric of the crankshaft, to offset the inertial loads generated by the moving members of the compression mechanism and by the eccentric itself.

As the name implies, the function of a counter-balance weight is to serve as the balancing force to offset the inertial load generated in a system. In the case of hermetic reciprocating compressor, the need for an optimum counter-balance weight is of utmost important as it will affect the vibration and noise performance of the compressor. However, with the increasing stiff competition from other compressors’ manufacturers, cost has also become an essential factor in determining the success of the product. Therefore, a new series of welded counter-balance weights have been designed and developed with the intention to minimize compressors’ noise and vibration level at minimal cost.