Centrifugal pumps are structured around "centrifugal force drive," primarily consisting of an impeller, pump casing, and shaft seal. During operation, the motor drives the impeller to rotate at high speed (typically 1000-3000 r/min). The impeller blades propel the fluid in a circular motion, and under centrifugal force, the fluid is thrown into the pump casing's flow channel, thus achieving pressure increase and delivery. Its flow channel is often volute-type, with the fluid flow path spiraling. It relies on the kinetic energy generated by high-speed rotation to convert into pressure energy, therefore requiring extremely high precision in impeller dynamic balance and smoothness of the flow channel.
Screw pumps, on the other hand, are designed around "positive displacement meshing transmission," and are available in single-screw, twin-screw, and triple-screw types. The core components are the screw and bushing (single screw) or meshing screws (multi-screw). During operation, the driving screw drives the driven screw to rotate. The screw and bushing (or between the screws) form a periodically changing sealed cavity. This cavity moves from the suction end to the discharge end as the screw rotates, "squeezing and pushing" the fluid out. Its structure emphasizes precise control of the meshing clearance (typically 0.05-0.1mm) to avoid fluid leakage. Simultaneously, the screw's helix angle and lead design directly affect flow stability.
The rotary cam pump belongs to the "rotor-type positive displacement pump" category. Its core structure consists of a pair of synchronously rotating counter-rotating cam rotors (mostly double-lobe or triple-lobe), a pump body, and a synchronous gearbox. The rotors rotate without contact within the pump chamber. Fluid intake and discharge are achieved through the periodic expansion and contraction of the sealed cavity formed between the rotor profile and the pump body. Unlike screw pumps, its rotors do not require precise meshing; instead, the synchronous gears ensure the rotor clearance (typically 0.1-0.3mm), resulting in a wider flow channel. Furthermore, the rotor structure can be designed with rubber coating or metal material depending on the medium characteristics.
