The twin-screw compressor is a double-shaft positive displacement compressor. It is mainly composed of the main (male) and vice (female) rotors to form a meshing pair. The tooth profile of the main and auxiliary rotors forms a closed base with the inner wall of the casing. The shortcoming of the double screw is that the 40 cubic and above models need to add a speed-increasing gear, which increases power consumption and is prone to head lock; while the worm compressor is a single-shaft positive displacement compressor with meshing The pair is composed of a worm and two star wheels arranged in a symmetrical plane. The worm screw groove, the tooth surface of the star wheel and the inner wall of the casing form a closed primitive volume, but the disadvantage is that the material of the star wheel needs to be improved.
The main performance parameters of screw air compressors are power, volumetric flow, suction pressure, outlet temperature, discharge pressure and speed. In the design of screw air compressors, a pair of intermeshing rotors is a very important parameter. Because it is closely related to the performance of the compressor. The male and female rotors of the screw compressor can be regarded as a pair of helical gears that mesh with each other. Therefore, the profile of the female and male rotors of the screw compressor must also satisfy the meshing law. The intersection line between the tooth surface of the rotor and the vertical plane of the rotor axis is called the rotor profile. The rotor profile of the screw compressor is divided into symmetric profile and asymmetric profile, as well as unilateral profile and double profile. When the profile on both sides of the tooth top center line is exactly the same, it is called symmetric profile. Conversely, when the profile lines on both sides of the tooth top center line are different, it is called an asymmetric profile. There is a profile line only on the inner or outer side of the rotor pitch circle, which is called a single-sided profile line. There are contour lines inside and outside the pitch circle, which are called bilateral contour lines. Generally speaking, the development and design of the new line directly affects the performance of the screw air compressor, and the performance of the screw air compressor also depends on the design of the profile.
The screw compressor relies on the continuous meshing of the rotor to output compressed gas. Therefore, the change of the spindle speed will affect the volume flow and exhaust pressure of the compressor. Therefore, the spindle speed is a major factor affecting the performance of the screw compressor. When the exhaust pressure increases, the power consumption of the compressor also increases, and the specific power increases, and the economic benefit decreases. Therefore, the exhaust pressure has a very significant impact on the energy consumption of the compressor. At the same time, some test results show that the external ambient temperature will also affect the performance of the screw compressor. The air temperature in China varies greatly in different seasons and in different regions, and the suction temperature of the compressor is different when the ambient temperature is different. This parameter will directly affect the performance of the screw compressor. Therefore, the analysis of the above factors affecting the performance of the screw compressor will greatly help the use of the screw compressor.
The body of the screw compressor is divided into two types, one is a belt drive type, and the other is a direct drive type. Among them, the belt drive type is more suitable for compressors with a power of about 22KW. The power is driven by two belt pulleys manufactured according to the speed ratio; the direct drive type is a coupling that combines the electric source with the main engine, and the worm type All compressors directly drive the worm to rotate, while the twin-screw compressor needs to add a step-increasing gear to increase the speed of the main rotor.
The working process of the twin-screw compressor: the motor drives the main rotor through the coupling, speed-increasing gear or belt. Because the two rotors mesh with each other, the main rotor directly drives the auxiliary rotor to rotate together. Under the action of relative negative pressure, air is sucked in. When the tooth crest and the tooth groove work together, the gas is transported and compressed. When the rotor meshing surface turns to communicate with the exhaust port of the casing, the compressed gas begins to be discharged.
The working process of the worm compressor: the motor transmits the power to the worm shaft through a coupling or a belt, and the worm drives the star gear teeth to move relatively in the worm groove. The volume of the closed element changes, and the gas and conveying are compressed. When the design is reached The pressure value is discharged from the symmetrical triangular exhaust ports on the left and right sides of the main body shell to the oil and gas separator.
The main body of the screw compressor has oil injection holes. With its own pressure difference, the oil is injected into the compression chamber during the compression process to cool the gas, seal the gaps of various parts, and play a role in absorbing vibration, silencing and lubricating.
