The simple “gear within gear” principle of Internal Eccentric Gear Pumps means that there are only two moving components within the process medium. The positive displacement is achieved by the filling of the cavities between the teeth of both the rotary and idler gears located in the pump head. With each revolution, a fixed volume of fluid enters the casing through the suction port, filling the space between the teeth of the gears. The crescent within the pump head then separates the fluid as the idler gear turns on the pump shaft.
Image 1: Fluid entering the pump
The orange-coloured section in the image represents the process medium as it is entering the pump suction port and the pump casing & filling the cavities between the Idler Gear (Red) & Rotary Gear (Brown). The three arrows indicate the direction of fluid passage through the pump and the rotational direction of the gears.
Image 2: Fluid filling the cavities & split of flow
As the fluid progresses through the pump head and fills the cavities between the gears, it is also separated by the crescent shape in the pump head, which acts as a seal preventing backflow between the suction & discharge ports.
Image 3: Pump almost flooded
As the fluid fully fills the casing, all cavities between the gears are completely filled in the form of locked pockets of fluid to guarantee absolute volume control and enable the pump to deliver a fixed volume per revolution.
Image 4: The pump is flooded & starts to discharge the process medium under pressure
Once the pump is fully flooded, the rotor and idler gears mesh together and form a liquid seal which is equidistant between the pump ports, which then enables the fluid to exit the discharge of the pump under pressure. The delivery pressure is dependent on the installed power of the motor.
