Centrifugal pump directly coupled to electric motor - has pilot impeller coupled to shaft with main impeller loose

摘要

The pump has a motor with a stator and a permanent magnet rotor on a shaft. The shaft extends into the pump casing and carries a pilot impeller rigidly fixed to it. The back of the pilot impeller forms one face of a clutch. The main impeller is loose on the shaft of the side of the pilot impeller opposite the suction inlet and has blades surrounding the pilot impeller. It carries the other face of the clutch. When the motor starts the pilot impeller produces a hydraulic force which moves the main impeller axially into contact to be driven through the clutch. If the pump is overloaded the clutch slips, the main impeller loses speed and the motor is not overloaded.