Jan 26, 2022

The basic structure of gear pump, and what is the function of each structure?


The structure of the gear pump


The structure of the gear pump is shown in the figure. When the driving gear of the pump rotates in the direction of the arrow shown in the figure, the gear on the right side of the gear pump (oil suction chamber) is disengaged, and the gear teeth of the gear exit between the teeth, which increases the sealing volume and forms a Partial vacuum, the oil in the oil tank enters between the teeth through the oil suction pipeline and the oil suction cavity under the action of the external atmospheric pressure. As the gear rotates, the oil sucked between the teeth is brought to the other side and enters the oil pressure chamber. At this time, the gear teeth are engaged, so that the sealing volume is gradually reduced, and the oil between the gears is squeezed out, forming the oil pressure process of the gear pump. When the gears are meshed, the tooth contact line separates the oil suction chamber and the oil pressure chamber and plays the role of oil distribution. When the driving gear of the gear pump is continuously rotated by the motor, the gear teeth are disengaged from the meshing side. As the sealing volume becomes larger, oil is continuously sucked from the oil tank, and the gear teeth enter the meshing side. As the sealing volume decreases, the Drain the oil, this is how the gear pump works. The front and rear covers of the pump and the pump body are positioned by two positioning pins 17, which are fastened with 6 screws as shown in Figure 3-3. In order to ensure that the gear can rotate flexibly and at the same time ensure the minimum leakage, there should be an appropriate clearance (axial clearance) between the end face of the gear and the pump cover. 0.04~0.06mm. The gap (radial clearance) between the tooth top and the inner surface of the pump body has little effect on the leakage due to the long sealing belt and the shear flow formed by the linear velocity of the tooth top and the direction of oil leakage. The problem is: when the gear is subjected to an unbalanced radial force, the contact between the tooth tip and the inner wall of the pump should be avoided, so the radial clearance can be slightly larger, generally 0.13~0.16mm.


In order to prevent the pressure oil from leaking from the pump body and the pump cover to the outside of the pump, and to reduce the tension of the compression screw, oil seal unloading grooves 16 are opened on the end faces on both sides of the pump body, so as to penetrate into the pump body and the pump cover. Pressure oil is introduced into the suction chamber. The small holes on the pump cover and the driven shaft will lead the pressure oil leaking to the end of the bearing to the suction chamber of the pump to prevent the oil from overflowing and also lubricate the needle roller bearing.


How do Gear Pumps work?

The working principle of the gear pump is shown in the figure. It is a three-piece structure. The three pieces refer to the pump cover 4, 8, and the pump body 7. The pump body 7 is equipped with a pair of teeth with the same number, the width and the pump body are close to each other and mesh with each other. The gear 6, the pair of gears, the two end caps, and the pump body form a sealing chamber, and the sealing chamber is divided into two parts by the tooth top and the meshing line of the gear, namely the oil suction chamber and the oil pressure chamber. The two gears are respectively fixed on the driving shaft 12 and the driven shaft 15 supported by needle roller bearings with keys, and the driving shaft is driven to rotate by the motor.


Worldwide famous gear pump brands have REXROTH AZPW, AZPF Series, PARKER PGP Series, Marzocchi Elika Series, etc.

We can advise the right Gear Pump solutions for your specific application.

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