The basic structure and principle of screw compressors

The basic structure and principle of screw compressors

1. Basic structure

The commonly referred to screw compressor refers to a twin screw compressor. Compared to piston compressors,It also belongs to volumetric compressors, but screw compressors are a relatively novel compressor structure Form.

In the body of the screw compressor, there is a pair of spiral rotors that mesh with each other in parallel.A rotor with convex teeth outside the pitch circle is usually referred to as a male rotor or a male screw. Normally, for oil injected screw compressors, the male rotor is connected to the prime mover, and the male rotor drives the female rotor to rotate Move. Therefore, the positive rotor is also known as the active rotor, and the lunar rotor is also known as the driven rotor. The back to back inclined column bearings on the compressor achieve axial positioning and withstand axial forces in the compressor. Similarly,The circular bearing at one end of the rotor enables radial positioning of the rotor and withstands radial forces in the compressor.Set up holes of a certain shape and size diagonally at the upper and lower ends of the compressor body.One for inhalation, called an inhalation port; The other is for exhaust, called an exhaust port.

2. Working principle

The working cycle of a screw compressor can be divided into three processes: suction, compression, and exhaust. along with The high-speed rotation of the rotor, where each pair of teeth that mesh with each other completes the same working cycle one after another, is called positive rotation The rotor rotates counterclockwise, while the female rotor rotates clockwise.

Three working cycle processes:

1) Inhalation process: As the rotor rotates relative to each other, it forms due to the gradual disengagement of one end of the teeth The expansion of the interdental volume creates a certain vacuum inside it, and At this point, the volume between the teeth is only connected to the suction port, so the gas flows into the teeth under the pressure difference Volume.

2) Compression process: With the relative rotation of the rotor, the volume between teeth decreases due to the meshing of the rotor teeth Break down. The volume occupied by the gas sealed in the volume between the teeth also decreases, resulting in The pressure increases to achieve the compression process of the gas

3) Exhaust process: As the volume between the teeth continues to decrease, the gas with exhaust pressure gradually passes through Discharged through the exhaust port.From the above working principle, it can be seen that screw compressors are a type of rotary motion with a working volume Positive displacement gas compressor. The gas is in the meshing rotor cavity, and the volume is constantly changing The pressure is constantly increasing.

3. Compression principle

The principle is very simple. The male rotor has 4 convex ribs and the female rotor has 6 grooves. These two spiral rotors are arranged in the opposite direction to each other Merge. The speed of the first rotor is 50% faster than the second one. The inhaled air is compressed between the rotor and the chamber. Spray in The oil will seal the gaps in the rotor and have a lubricating effect, thereby minimizing wear.

1) The tail end of the rotor opens the inlet, and air enters the compression chamber;

2) Air is introduced into a "cavity" composed of convex ribs and grooves;

3) As the rotor rotates, the cavity becomes smaller and the introduced air is compressed;

4) Compressed air is released through the discharge port