What is the working principle of an oil-free screw air compressor, and what are its advantages and disadvantages?

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Oil-free screw air compressor is a common air compressor, which can compress air through the rotation of the screw, and does not need lubricating oil to lubricate and cool the screw. How it works and its pros and cons are as follows:

01
working principle

The oil-free screw air compressor is a volumetric gas compression machine whose working volume makes a rotary motion. The compression of gas is realized by the change of volume, and the change of volume is achieved by means of a pair of rotors of the air compressor rotating in the casing.

02
Overview of how it works

In the body of the compressor, a pair of intermeshing helical rotors are arranged in parallel, and the rotors with convex teeth outside the pitch circle are usually called male rotors or male screws. The rotor with concave teeth in the pitch circle is called the female rotor or the female screw. Generally, the male rotor is connected with the prime mover, and the male rotor drives the female rotor to turn the last pair of bearings on the rotor to achieve axial positioning and bear the pressure of the compressor. axial force. Cylindrical roller bearings at both ends of the rotor allow the rotor to be positioned radially and withstand the radial forces in the compressor. At both ends of the compressor body, orifices of a certain shape and size are respectively opened. One is used for suction and is called the air inlet; the other is used for exhaust and is called the exhaust port.

03
air intake

The air intake process of the detailed analysis of the working process of the screw air compressor: when the rotor rotates, when the tooth groove space of the male and female rotors turns to the opening of the intake end wall, the space is the largest. At this time, the rotor tooth groove space communicates with the air inlet. , because the gas in the tooth groove is completely discharged during the exhaust, and the tooth groove is in a vacuum state when the exhaust is completed. When the gas fills the entire tooth groove, the end surface of the rotor inlet side turns away from the air inlet of the casing, and the gas in the tooth groove is sealed.

04
compression

The working process of the screw air compressor is analyzed in detail in the compression process: when the male and female rotors end inhalation, the tooth tips of the male and female rotors will be closed with the casing, and the gas will no longer flow out in the tooth groove. Its engaging surface gradually moves towards the exhaust end. The tooth groove space between the meshing surface and the exhaust port is gradually reduced, and the gas in the tooth groove is compressed and the pressure is increased.

05
exhaust

The exhaust process of the detailed analysis of the working process of the screw air compressor: when the meshing end surface of the rotor turns to communicate with the exhaust port of the casing, the compressed gas starts to be discharged until the meshing surface of the tooth tip and the tooth groove moves to the exhaust port. At this time, the tooth groove space between the meshing surface of the male and female rotors and the exhaust port of the casing is 0, that is, the exhaust process is completed. At the same time, the tooth groove length between the meshing surface of the rotor and the air inlet of the casing reaches the maximum. Long, the air intake process is carried out again.

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advantage

01
The oil-free screw air compressor does not need to use lubricating oil, so it can greatly reduce the maintenance cost, and also reduce the oil pollution in the air
02
Since the oil-free screw air compressor does not need to use lubricating oil, it can also avoid failures caused by oil corrosion or excessive use

03
The oil-free screw air compressor has low noise and vibration during operation, so it is suitable for occasions that require a quiet environment
04
Since the oil-free screw air compressor has no lubricating oil, it also avoids the problem of polluting the environment due to oil leakage
shortcoming

01
Since the oil-free screw air compressor has no lubricating oil to cool the screw, it is prone to failures such as screw deformation or burning in high temperature environments

02
The cost of oil-free screw air compressor is usually higher, so it is not suitable for all occasions
03
The compression ratio of oil-free screw air compressors is usually low, so it may not meet the requirements in some applications that require high-pressure gas

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