Screw compressor is a positive displacement gas compression machine whose working volume makes rotary motion. The compression of gas is achieved by changes in volume, and the change in volume is achieved by the rotation of a pair of rotors of the compressor in the casing.
The basic structure of a screw air compressor:
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 male screw. The rotor with concave teeth in the pitch circle is called a female rotor or a female screw. Generally, the male rotor is connected to the prime mover. The male rotor drives the female rotor to rotate the last pair of bearings on the rotor to achieve axial positioning and bear the axial force in the compressor. Cylindrical roller bearings at both ends of the rotor position the rotor radially and withstand radial forces in the compressor. At both ends of the compressor body, openings of a certain shape and size are provided. One is for suction and is called the air inlet; the other is for exhaust and is called the exhaust port.
Working principle of screw air compressor
(1) Inhale: When the motor-driven/internal-combustion engine rotor rotates the tooth groove space of the master-slave rotor to the opening of the air inlet end wall, the space is large and the outside air fills it. When the air inlet side end face of the rotor turns away from the air inlet of the shell, The air between the tooth grooves is enclosed between the main and slave rotors and the casing, completing the suction process.
(2) Compression: At the end of suction, the closed volume formed by the master and slave rotor tooth peaks and the casing decreases with the change of the rotor angle and moves in a spiral. This is the "compression process".
(3) Compressed gas and fuel injection process: During the transportation process, the volume continues to decrease, the gas continues to be compressed, the pressure increases, and the temperature increases. At the same time, the lubricating oil that becomes mist due to the air pressure difference is sprayed into the compression chamber, thereby achieving compression, temperature reduction, sealing and lubrication. effect.
(4) Exhaust process: When the closed tooth peak of the rotor rotates to meet the exhaust port of the casing, the compressed air begins to be discharged until the matching surface between the tooth peak and the tooth groove moves to the exhaust end face. At this time, the tooth groove space is zero, that is, the exhaust is completed. gas process. At the same time, the other pair of tooth grooves of the master and slave rotors has rotated to the intake end, forming the largest space to start the suction process, thus starting a new compression cycle.
