The gear pump is driven by a separate motor that effectively blocks upstream pressure pulsations and flow fluctuations. The pressure pulsation at the outlet of the gear pump can be controlled within 1%. The use of a gear pump on the extrusion line increases the flow rate and reduces the shear and residence time of the material in the extruder.
The external gear pump is the most widely used gear pump. The general gear pump usually refers to the external gear pump. Its structure is shown in Figure 5-14, which mainly consists of a driving gear, a driven gear, a pump body, a pump cover and a safety valve. The sealed space formed by the pump body, the pump cover and the gears is the working chamber of the gear pump. The axles of the two gears are respectively mounted in bearing holes on the two pump covers, and the driving gear shaft extends out of the pump body and is rotated by the motor. The external gear pump has the advantages of simple structure, light weight, low cost, reliable operation and wide application range.
When the gear pump is working, the driving wheel rotates with the motor and drives the driven wheel to rotate. When the meshing teeth on one side of the suction chamber are gradually separated, the volume of the suction chamber is increased, and the pressure is lowered, and the liquid in the suction pipe is sucked into the pump; the suction liquid is pushed into the discharge chamber by the gear in two directions in the tooth groove. After the liquid enters the discharge chamber, the liquid is squeezed from the discharge chamber into the discharge tube due to the continuous engagement of the teeth of the two gears. The drive and driven gears rotate continuously, and the pump continuously draws in and discharges liquid.
