Working principle of internal gear pump

With the rapid development of industrial society, the application scope of internal gear pump is more and more wide, and the requirements are also higher and higher. In addition to improving its work efficiency, it is also necessary to reduce the noise generated in the operation process as far as possible. Therefore, in terms of the development of internal gear pump, reducing its operation noise is conducive to promoting the development of internal gear pump and prolonging its service life.

There are two kinds of internal gear pump: involute gear pump and cycloid gear pump. In the involute internal gear pump, a crescent diaphragm should be installed between the pinion and the internal gear to separate the oil suction cavity and the oil pressure cavity. The pinion in the internal gear pump is the driving gear, and the large gear is the driven gear. When working, the large gear rotates in the same direction with the pinion, as shown in figure (a); the cycloid gear pump is also called the cycloid rotor pump. In this kind of pump, the small gear is the driving gear There is only one tooth difference between the wheel and the internal gear, so there is no need to set a diaphragm, as shown in Fig. (b).

The internal gear pump adopts the principle of internal gear engagement. The pitch circle of internal and external gears is close to one side, and the other side is separated by the “crescent plate” on the pump cover. The driving internal gear on the main shaft drives the internal and external gears to rotate in the same direction. At the inlet, the gears separate from each other to form a negative pressure and inhale the liquid. At the outlet, the gears continuously embed and mesh to extrude the liquid.

The internal gear pump has the advantages of no trapped oil phenomenon, stable transportation, high efficiency, low noise and long service life.

(a) (b) is the structural diagram of internal gear pump, which is mainly composed of 1 pinion, 2 outer gear ring, 3 crescent plate, 4 oil inlet chamber and 5 oil outlet chamber.

Compared with the external gear pump, the internal gear pump itself plays a certain role in reducing the noise. However, taking more effective measures to reduce the noise is more conducive to the development of the gear pump, and is more conducive to improving the service efficiency and life of the gear pump. From the specific causes of noise, the corresponding specific measures are formulated. Through the effective control of the flow pulsation, oil trapping, cavitation and cavitation, gear meshing impact and the noise caused by mechanical factors, the goal of reducing noise is achieved.

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