The concept of the gear pump is very simple, that is, the fundamental way of the gear pump is that two gears of the same size mesh with each other and rotate in a tightly matched housing. The inside of this housing is similar to the "8" shape, and the two gears are installed inside. , The outer diameter and both sides of the gear are closely matched with the shell. The material from the extruder enters the middle of the two gears at the suction port and overflows this space. It moves along the housing with the rotation of the teeth and then is discharged when the two teeth mesh.

In terminology, a gear pump is also called a positive displacement installation, that is, like a piston in a cylinder, when one tooth enters the fluid space of another tooth, the liquid is mechanically squeezed out. Since the liquid is incompressible, the liquid and the teeth cannot occupy the same space at the same time, so that the liquid is swept away.

This phenomenon occurs continuously due to the meshing of teeth from time to time, so a continuous sweeping amount is provided at the outlet of the gear pump. The discharge amount is the same for each revolution of the gear pump. With the discontinuous rotation of the drive shaft, the gear pump discontinuously discharges fluid. The flow rate of the gear pump is directly related to the speed of the pump.

In practice, there is a very small amount of fluid loss in the gear pump, which makes the gear pump's operating efficiency cannot reach 100%. Because these fluids are used to smooth bearings and gears on both sides, the gear pump body may also have no clearance fit Therefore, the fluid cannot be discharged 100% from the outlet, so a small amount of fluid loss is inevitable. But the gear pump can still run well, and for most of the extruded materials, it can still reach 93%~98% efficiency.

For details, please consult: vane pump.