An oil-free screw air compressor is a common air compressor that can compress air by rotating the screw, and does not require the use of lubricating oil to lubricate and cool the screw.
一：Working principle:
An oil-free screw air compressor is a positive displacement gas compression machine that rotates the working volume. The compression of the gas is achieved by the change in volume, and the change in volume is achieved by the rotation of a pair of rotors of the air compressor in the casing.
In the compressor body, a pair of mutually meshing spiral rotors are arranged in parallel. The rotor with convex teeth outside the pitch circle is usually called a male rotor or a male screw. The rotor with concave teeth inside the pitch circle is called a female rotor or a female screw. Generally, the male rotor is connected to the prime mover, and the male rotor drives the female rotor to rotate. The last pair of bearings on the rotor realizes axial positioning and bears the axial force in the compressor. The cylindrical roller bearings at both ends of the rotor enable the rotor to achieve radial positioning and bear the radial force in the compressor. At both ends of the compressor body, holes of certain shapes and sizes are opened respectively. One is for suction, called the air inlet; the other is for exhaust, called the exhaust port.
二：Intake:
Detailed analysis of the working process of the screw air compressor: When the rotor rotates, the tooth groove space of the yin and yang rotors is the largest when it turns to the opening of the intake end wall. At this time, the rotor tooth groove space is connected to the intake port. Because the gas in the tooth groove is completely discharged during exhaust, the tooth groove is in a vacuum state when the exhaust is completed. When it turns to the intake port, the external gas is sucked in and enters the tooth groove of the yin and yang rotors axially. When the gas fills the entire tooth groove, the end face of the rotor intake side turns away from the casing intake port, and the gas in the tooth groove is closed.
三：Compression:
Detailed analysis of the working process of the screw air compressor: When the yin and yang rotors finish inhaling, the yin and yang rotor tooth tips will be closed with the casing, and the gas will no longer flow out of the tooth groove. Its meshing surface gradually moves toward the exhaust end. The tooth groove space between the meshing surface and the exhaust port gradually becomes smaller, and the gas in the tooth groove is compressed and the pressure increases.
四：Exhaust:
Detailed analysis of the working process of the screw air compressor 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 discharged 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 yin and yang 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 longest, and the intake process is carried out again.
五：Is it really oil-free?
Regarding the question of whether the oil-free air compressor is really oil-free, it actually needs to be understood from multiple angles: No oil in the compression chamber: Literally, oil-free air compressors do mean that no oil is used in the compression chamber. This is one of the main differences between oil-free air compressors and traditional oil-containing air compressors. In oil-containing air compressors, lubricating oil is used to lubricate and cool mechanical parts and may be in direct contact with the compressed air. In oil-free air compressors, however, special designs and technologies are used to achieve lubrication and cooling of mechanical parts, thereby avoiding contact between oil and compressed air. Presence of oil vapor in the atmosphere: However, it should be noted that oil-free air compressors cannot remove oil vapor that already exists in the atmosphere. Therefore, even if oil-free air compressors do not use oil during the compression process, the compressed air output may still contain trace amounts of oil impurities. The content of these impurities is affected by many factors, including region, air quality, the environment of the air compressor room, and the cleanliness of the compressor. Lubrication and cooling of other parts: Although oil-free air compressors do not use oil in the compression chamber, in order to ensure the normal operation of the equipment and the lubrication of the parts, it still uses oil to cool the compressor and lubricate its operating parts. These oils are usually enclosed in specific areas of the equipment and do not come into direct contact with the compressed air. Therefore, from this point of view, oil-free air compressors are not completely oil-free.
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