The rotor profile is defined as the line of intersection between the rotor's tooth surface and a plane perpendicular to the rotor axis. Its evolution has progressed through three generations: the first generation featured symmetric circular arc profiles; the second generation introduced asymmetric profiles with tooth curves composed of points, straight lines, and cycloids; and the third generation utilized asymmetric profiles incorporating curves such as circular arcs, ellipses, and parabolas. Preliminary design principles for rotor profiles dictate that the contact line should be short and continuous, the area of the leakage triangle and the enclosed volume should be minimized, and the inter-tooth area should be maximized.
In oil-injected screw compressors, lubricating oil serves the functions of lubrication, cooling, and sealing. The oil injection rate is typically determined based on the compressor's thermal balance equation. Compressor oil must withstand prolonged use in high-temperature, high-pressure environments; therefore, it requires excellent high-temperature oxidation stability, low carbon-forming tendencies, appropriate viscosity and viscosity-temperature characteristics, as well as good oil-water separation, rust prevention, and corrosion resistance.
Bearing selection must take load conditions into account to ensure consistent service life across all bearings. The sealing system of the screw compressor's main unit primarily consists of a seal at the discharge end (oil seal) and a seal at the suction-end casing shaft extension (gas seal).
Performance Regulation Technology
Twin-screw compressors employ a slide valve mechanism to achieve stepless capacity regulation. The slide valve enables continuous control of capacity; by moving the valve laterally, the effective compression volume is increased or decreased, thereby regulating the gas delivery rate.
