Knowledge about Oil-free Screw Air Compressor

Oil-free screw air compressor is a common air compressor, which can compress air through the rotation of the screw and does not need to use lubricating oil to lubricate and cool the screw. Its working principle, advantages and disadvantages are as follows:

First, the working principle

01 working principle

Oil-free screw air compressor is a kind of positive displacement gas compressor with rotary working volume. 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 of the air compressor in the casing.

Overview of 02 working principle

In the compressor body, a pair of mutually meshing spiral 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 a female rotor or a female screw. Generally, the male rotor is connected with the prime Mover, and the male rotor drives the female rotor to rotate the last pair of bearings on the rotor to realize axial positioning and bear the axial force in the compressor. Cylindrical roller bearings at both ends of the rotor make the rotor realize radial positioning and bear the radial force in the compressor. The two ends of the compressor body are respectively provided with orifices with certain shapes and sizes. One for inhalation, called air inlet; The other is for exhaust, called exhaust port.

03 air intake

The working process of the screw air compressor is analyzed in detail. The air intake process: when the rotor rotates, the space of the tooth space of the male and female rotors is the largest when it is turned to the opening of the air intake end wall. At this time, the tooth space of the rotor is communicated with the air intake, because the gas in the tooth space is completely exhausted during the exhaust, when the exhaust is completed, the tooth space is in a vacuum state. When it is turned to the air intake, the external air is sucked in and enters the tooth space of the male and female rotors along the axial direction. When the gas fills the whole gullet, the end face of the rotor at the air inlet side turns away from the air inlet of the casing, and the gas in the gullet is sealed.

04 compression

The working process of screw air compressor is analyzed in detail. The compression process: when the suction of the male and female rotors is over, 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 meshing surface gradually moves to the exhaust end. The space between the meshing surface and the exhaust port is gradually smaller, and the gas in the tooth space is increased by compression pressure.

05 exhaust

The working process of the screw air compressor is analyzed in detail. The exhaust process: When the meshing end face of the rotor turns to communicate with the exhaust port of the casing, the compressed gas begins to be exhausted until the meshing surface of the tooth tip and the tooth groove moves to the exhaust end face. 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 zero, that is, the exhaust process is completed, and at the same time, the length of the tooth groove between the meshing surface of the rotor and the air inlet of the casing reaches the longest, and the air intake process is carried out again.

Secondly,advantages and disadvantages

Advantage

Oil-free screw air compressor does not need lubricating oil, so it can greatly reduce the maintenance cost and reduce the oil pollutants in the air.

Because the oil-free screw air compressor does not need to use lubricating oil, it can also avoid the failure caused by oil corruption or excessive use.

Oil-free screw air compressor has low noise and vibration when working, so it is suitable for occasions that need quiet environment.

Because the oil-free screw air compressor has no lubricating oil, it also avoids the problem of environmental pollution due to oil leakage.

Disadvantage

Because the oil-free screw air compressor has no lubricating oil to cool the screw, it is prone to screw deformation or burning in high temperature environment.

The cost of oil-free screw air compressor is usually high, so it is not suitable for all occasions.

The compression ratio of oil-free screw air compressor is usually low, so it may not meet the requirements in some applications that need high-pressure gas.