Rotary Gear Pump-Basics and Working Principle

A rotary gear pump is a kind of rotary pump, which occupies a very important position in daily production. So do you know the concept of the rotary gear pump? Next ATO will introduce the information of rotary gear pump for you in detail.

Rotary Gear Pumps Basics

A rotary gear pump is a rotary pump that relies on the change and movement of the working volume formed by the pump cylinder and the meshing gears to convey liquid or to pressurize it. In terms of terminology, gear pump is also called positive displacement device, that is to say, like a piston in a cylinder, when a gear into the fluid space of another tooth, because the liquid is incompressible, the liquid and gears can’t occupy the same space at the same time. The interior of the shell is similar to the "8", and two gears installed in it. The gears of the outer diameter and both sides of the gear are closely matched with the shell. The material from the extruder at the suction port enters the middle of the two gears to fills this space, moving along the housing with the rotation of the teeth and finally discharging when the two teeth are engaged. Due to the continuous engagement of the teeth, this phenomenon is continuously going. And therefore it also provide a continuous amount of discharge in the pump outlet, when the pump each rotation, the discharge is the same amount. With the uninterrupted rotation of the drive shaft, the pump will be uninterrupted discharge of fluid. In its basic form, two gears of the same size rotate in a tightly fitted housing that meshes with each other.

According to the criteria of core component gears, rotary gear pumps can be classified into metric line gear pumps and circular arc gear pumps. The public law line gear pump conveys impurity-containing media more durable than the circular arc rotary gear pump, while the circular arc gear pump has a special structure, conveys clean media, low noise and long life.

How Does the Gear Pump Work?

When the rotary gear pump works, the main wheel rotates with the motor and drives the driven wheel to follow the rotation. When the meshing teeth on the side of the suction chamber gradually separate, the volume of the suction chamber increases and the pressure decreases, and the liquid in the suction tube is sucked into the pump; the suction liquid is pushed to the discharge chamber by the gears in the tooth grooves in two ways. After the liquid enters the discharge chamber, as the teeth of the two gears keep meshing, the liquid is squeezed and enters the discharge pipe from the discharge chamber. The main gear and the driven gear keep rotating, the pump can continuously suck in and discharge the liquid.

At the same time, different accessories in the gear pump play a role in protecting the pump body and improving efficiency during operation. For example, the pump body is equipped with a safety valve, when the discharge pressure exceeds the specified pressure, the transported liquid can automatically open the safety valve, so that the high pressure liquid back to the suction pipe. The gear pump is driven by an independent motor, which can effectively block the upstream pressure pulsation and flow fluctuation. The pressure pulsation at the outlet of the rotary gear pump can be controlled to within 1%. The use of a gear pump in the extrusion line can increase the flow output speed and reduce the shear and residence time of the material in the extruder. The pump is also equipped with a differential pressure safety valve for overload protection, and the full return pressure of the safety valve is 1.5 times the rated discharge pressure of the pump. It can also be adjusted according to the actual needs within the allowable discharge pressure. But this safety valve can be used as a pressure reducing valve for long-term work, pressure reducing valve can be installed separately when needed. Nowadays, the gears adopt the new technology of international advanced level in 1990s - double arc sine curve tooth arc. Its most outstanding advantage compared with involute gears is that there is no relative sliding on the tooth profile surface during gear meshing, so there is no wear on the tooth surface, balanced operation, no trapped liquid phenomenon, low noise, long life and high efficiency. The pump is free from the traditional design, which makes the gear pump enter a new field in design, production and use.

Advantages

Simple and compact structure, small volume, light weight, good workmanship, cheap price, strong self-priming force, insensitive to oil pollution, large speed range, able to resist impact loads, easy maintenance and reliable work.

Disadvantages

Unbalanced radial force, large flow pulsation, high noise, low efficiency, poor interchangeability of parts, not easy to repair after wear, can't be used as a variable pump.