Basic Principles and Structure of Screw Air Compressors

2025 11/17

Volumetric Compression Principle

      Screw air compressor achieve volumetric compression through a pair of meshing male and female rotors (the male rotor has convex teeth, the female rotor has concave teeth). When the motor drives the rotors to rotate at high speed, the closed "basic volume" formed between the rotors and between the rotors and the inner wall of the casing continuously shrinks during the rotor meshing process. Air is forcibly compressed within this closed space, and after the pressure increases, it is discharged. This process consists of four stages:

 

 

1. Intake Stage: When the rotor tooth space rotates into the air inlet opening of the casing, the tooth space is in a vacuum state, drawing in outside air.

2. Compression Stage: As the rotor continues to rotate, the basic volume shrinks, the air molecule density increases, and the pressure gradually rises to the target working pressure (e.g., 0.7-1.3 MPa).

3. Exhaust Stage: When the basic volume shrinks to the point of connecting with the exhaust port, the high-pressure air is discharged to the oil-gas separator under the compression of the rotor.

4. Post-treatment stage: After the oil-gas mixture is filtered by the air compressor filter element and separated by centrifugation, the compressed air enters the cooling system to cool down, and then passes through equipment such as air compressor air dryer and air compressor precision filter to output clean air.