How does an internal gear pump prevent fluid from flowing back through the motor?

An internal gear pump prevents fluid from flowing back through the motor primarily by creating a sealing mechanism through its design, specifically the arrangement of its gears. In this type of pump, the meshing of the internal and external gears creates cavities that carry the fluid from the inlet to the outlet. Because the gears are positioned in such a way that they effectively trap the fluid, backflow is prevented as long as there is sufficient pressure in the system.

The number of teeth on the internal gear contributes to the overall efficiency and pressure characteristics of the pump, influencing how flow is regulated and sealed; however, what truly matters for backflow prevention is how the gears interlock to prevent any reverse movement of fluid.

A one-way valve typically allows for flow in one direction while preventing reverse flow, but an internal gear pump relies on its gear mechanism rather than additional components to achieve this effect. Similarly, a vacuum seal is not a feature of internal gear pumps, as their operation is based on fluid displacement rather than vacuum generation. Lastly, while increased fluid pressure can aid in maintaining flow direction, it is the mechanical design of the pump that inherently prevents backflow in the first place.