Scroll compressors

Scroll compressors structure and operation

A scroll compressor is one type of oil-free orbital motion, positive-displacement compressor. The compressor element consists of two interfitting, spiral-shaped scroll spirals, a stator spiral is fixed in a housing and the other is motor-driven eccentric, orbiting spiral. The spirals are mounted with 180° phase displacement or mirror displacement. The orbiting spiral is driven by a short-stroke crankshaft and runs eccentrically around the center of the fixed spiral. The inlet is situated at the top of the element housing. This movement forms air pockets with a gradually varying volume. By this way, scroll compressor compresses a specific amount of air into a continuously decreasing volume.

Scroll compressors features

This motion of spirals provides the scroll elements with radial stability. Leakage can be minimized because the pressure difference in the air pockets is lower than the pressure difference between the inlet and the outlet.

When the orbiting spiral moves, air is drawn in and is captured in one of the air pockets, where it is compressed gradually while moving towards the center where the outlet port and a non-return valve are situated. The compression cycle is in progress for 2.5 turns, which virtually gives constant and pulsation-free air flow. Scroll compressors have many distinctly appealing qualities. They are efficient, quiet, and reliable and vibration-free, as the element has hardly any torque variation as compared to a piston compressor, for example.