A screw pump is a positive displacement rotary pump, and its structure varies depending on the type (e.g., single-screw, twin-screw, three-screw, etc.). A screw pump typically consists of a core working component (screw pair), pump body, sealing device, and transmission support components. Its structural design directly affects the pump's flow rate, pressure, media adaptability, and service life.
The core structure of a single-screw pump (also known as a Mono pump) is a rotor-stator pair consisting of a single-headed helical metal rotor (screw) and an elastic stator with a double-headed helical inner cavity. The rotor performs planetary rotation within the stator cavity, and the two mesh to form a continuous sealed cavity, achieving axial transport of the media.
The core structure of a multi-screw pump (such as a twin-screw pump or a three-screw pump) consists of two or three meshing screws. Taking a three-screw pump as an example, it typically includes one male (active) drive screw and two female (driven) screws, housed within a precision pump body (shroud). The meshing of the screw and the inner wall of the pump body together form a series of closed spiral spaces (sealing cavities).
In addition to the core screw assembly, screw pumps typically include the following components: a pump body (casing) to house the screw and form a pressure boundary; a shaft seal (such as a mechanical seal) to prevent leakage of the medium from the shaft extension; bearings to support the shaft; and a coupling or transmission mechanism to connect the drive motor to the pump shaft. Some pump models also include accessories such as safety valves and heating/cooling jackets.
Modern screw pump designs emphasize compactness, reliability, and ease of maintenance. For example, they employ front-mounted, fully replaceable seal cartridge designs for quick maintenance; robust all-stainless steel gearboxes with timing gears placed between bearings to optimize bearing load and reduce vibration and noise; and pump body designs that allow for 180-degree rotation to change the inlet and outlet directions, increasing installation flexibility.
