Gear pump principle



The working principle of Taiwan Sun Hung gear pump The English name of the gear pump: Gearwheelpump working principle analysis is a rotary pump that relies on the change and movement of the working volume formed between the pump cylinder and the meshing gear to transport liquid or pressurize it. The structure of the external gear pump. A pair of meshing gears and pump cylinders separate the suction chamber from the discharge chamber. When the gear rotates, the volume between the teeth where the teeth on the suction cavity side disengage from each other gradually increases, the pressure decreases, and the liquid enters the teeth under the action of the pressure difference. As the gear rotates, the liquid between the teeth is brought to the discharge chamber.

Introduction to the working principle of gear pumps

The concept of a gear pump is very simple, that is, its relatively basic form is that two gears of the same size mesh with each other in a close-fitting shell. The inside of the shell is similar to the "8" shape, and two gears are installed inside. , The outer diameter and both sides of the gear fit tightly with the housing. The material from the extruder enters the middle of the two gears at the suction port, and fills the space, moves along the housing with the rotation of the teeth, and is discharged when the two teeth are meshed after comparison. To

In terms of terminology, 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, the liquid is mechanically squeezed out. Because the liquid is incompressible, the liquid and the tooth cannot occupy the same space at the same time, so the liquid is eliminated. Due to the continuous meshing of the teeth, this phenomenon occurs continuously, so a continuous discharge amount is provided at the outlet of the pump, and the discharge amount is the same for each revolution of the pump. With the uninterrupted rotation of the drive shaft, the pump continuously discharges fluid. The flow rate of the pump is directly related to the speed of the pump. To

In fact, there is a small amount of fluid loss in the pump, which makes the pump's operating efficiency unable to reach 100%, because these fluids are used to lubricate the bearings and both sides of the gear, 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. However, the pump can still run well, and for most extruded materials, it can still reach an efficiency of 93% to 98%. To

For fluids whose viscosity or density changes during the process, this pump will not be affected too much. If there is a damper, such as a strainer or a restrictor on the side of the discharge port, the pump will push the fluid through them. If this damper changes during operation, that is, if the filter screen becomes dirty, clogged, or the back pressure of the limiter increases, the pump will still maintain a constant flow rate until the mechanical limit of the weaker part of the device is reached. (Usually equipped with a torque limiter). To

There is actually a limit to the speed of a pump, which mainly depends on the process fluid. If the oil is conveyed, the pump can rotate at a very high speed, but when the fluid is a high-viscosity polymer melt In the physical, this restriction will be greatly reduced. To

It is very important to push the high-viscosity fluid into the two-tooth space on the side of the suction port. If this space is not filled, the pump will not be able to discharge the accurate flow rate. Therefore, the PV value (pressure × flow rate) is another limiting factor, and It is a process variable. Due to these limitations, gear pump manufacturers will provide a series of products, that is, different specifications and displacement (amount discharged per revolution). These pumps will be matched with the specific application process to make the system capacity and price better. To

The gear and shaft of the HGP pump are integrated, and the whole body hardening process is adopted to obtain a longer working life. The "D" type bearing incorporates a forced lubrication mechanism that allows the polymer to pass through the bearing surface and return to the inlet side of the pump to ensure effective lubrication of the rotating shaft. This feature reduces the possibility of polymer retention and degradation. The precision-machined pump body can accurately match the "D" type bearing with the gear shaft to ensure that the gear shaft is not eccentric to prevent gear wear. Parkool seal structure and PTFE lip seal together form a water-cooled seal. This kind of seal does not actually touch the surface of the shaft. Its sealing principle is to cool the polymer to a semi-molten state to form a self-seal. Rheoseal seal can also be used, which has reverse spiral grooves on the inner surface of the shaft seal, which can make the polymer back pressure back to the inlet. In order to facilitate installation, the manufacturer has designed a ring bolt mounting surface to match the flange installation of other equipment, which makes the manufacture of cylindrical flanges easier. To

The HGP gear pump has heating elements that match the pump specifications, which can be selected by users, which can ensure rapid heating and heat control. Different from the heating method in the pump body, the damage of these components is limited to one board and has nothing to do with the entire pump. To

The gear pump is driven by an independent group motor, which can effectively block the upstream pressure pulsation and flow fluctuation. The pressure pulsation at the outlet of the gear pump can be controlled within 1%. Using a gear pump in the extrusion production line can increase the flow output speed, reduce the shear and residence time of the material in the extruder, and reduce the extrusion temperature and pressure pulsation to improve productivity and product quality.