What is the working principle of hydraulic gear pump?

The working principle of the hydraulic gear pump is that when the gear rotates, the space volume on the gear disengagement side changes from small to large, forming vacuum and sucking liquid, and the space volume on the gear engagement side changes from large to small, thus squeezing the liquid into the pipeline.

Technically, a gear pump is also called a positive displacement device, that is, like a piston in a cylinder, when one tooth enters the fluid space of another tooth, because the liquid is incompressible, the liquid and the tooth cannot occupy the same space at the same time, thus mechanically squeezing out the liquid.

This phenomenon occurs continuously due to the continuous meshing of the teeth, providing continuous discharge at the outlet of the pump. Every time the pump rotates, the discharge is the same. With the continuous rotation of the drive shaft, the pump also continuously discharges fluid. The flow rate of the pump is directly related to the speed of the pump.

In fact, there is a small amount of fluid loss in the pump, because these fluids are used to lubricate bearings and gears, and the pump body can never fit without clearance, so the fluid cannot be discharged from the outlet 100%, so a small amount of fluid loss is inevitable, which makes the working efficiency of the pump unable to reach 100%.

However, the pump can still run well, and the efficiency can still reach 93% ~ 98% for most extruded materials.

Extended data

The hydraulic gear pump is driven by an independent motor, which can effectively block the upstream pressure pulsation and flow fluctuation. The pressure pulsation at the gear pump outlet can be controlled within 65438 0%. Using hydraulic gear pump in extrusion production line can improve the flow output speed and reduce the shearing and residence time of materials in extruder.

External gear pump is the most widely used hydraulic gear pump, and general hydraulic gear pump usually refers to external gear pump. It is mainly composed of driving gear, driven gear, pump body, pump cover and safety valve. The sealed space composed of pump body, pump cover and gear is the working room of gear pump.

The shafts of the two gears are respectively installed in the bearing holes on the two pump covers, and the driving gear shaft extends out of the pump body and is driven by the motor to rotate. External gear pump has simple structure, reliable operation and wide application range.

When the hydraulic gear pump works, the driving wheel rotates with the motor and drives the driven wheel to rotate with it. When the meshing teeth on one side of the suction cavity are gradually separated, the volume of the suction cavity increases and the pressure decreases, so that the liquid in the suction tube is sucked into the pump; Suction liquid is pushed to the discharge chamber by the gear in the tooth slot in two ways.

After the liquid enters the discharge chamber, due to the continuous meshing of the teeth of the two gears, the liquid is squeezed and enters the discharge pipe from the discharge chamber. When the driving gear and the driven gear keep rotating, the pump can continuously suck and discharge liquid.

The hydraulic pump body is equipped with a safety valve. When the discharge pressure exceeds the specified pressure, the conveying liquid can automatically open the safety valve and return the high-pressure liquid to the suction pipe.

Baidu encyclopedia-hydraulic gear pump