Screw compressor is a volumetric gas compression machine with working volume for rotary motion. The compression of gas depends on the change of volume, and the change of volume is achieved by the rotary motion of a pair of rotors in the housing of the compressor. Basic structure: in the body of the compressor, a pair of helical rotors are arranged in parallel to each other. Usually, the rotor with convex teeth outside the section circle is called the Yang rotor or Yang screw. The rotor with concave teeth in the section circle is called Yin rotor or Yin screw, a Yang rotor is connected with the prime mover, driven by the Yang rotor Yin rotor rotor rotation on the last pair of bearings to achieve axial positioning, and bear the axial force in the compressor. Cylindrical roller bearings at both ends of the rotor enable the rotor to achieve radial positioning and withstand radial forces in the compressor. At both ends of the compressor body, a certain shape and size of the orifice are respectively opened. One for inhalation, called the air inlet; The other is used for exhaust, called exhaust port.