Cycloidal tooth profile of the internal gear pump, also called cycloidal rotor pump, pump the small gear and internal gear only related a tooth, so the internal gear pump do not need to set partition.

Two methods of reducing cogging torque, namely, the stator tooth notching and the two rotor pole stacks shifting are presented.

In this paper, the design theory and method of rotor tooth model line for fans with symmetrical screw, its design parameter and so on are discussed and studied.