What role does the hydraulic gear pump play in the hydraulic system? The heart of the hydraulic system is the hydraulic gear pump, referred to as the oil pump. So in a hydraulic system, you have to have a pump. Hydraulic gear pump is a kind of energy conversion device, flow movement is its role, from mechanical energy into fluid energy. Pump is the power element in the hydraulic transmission system, driven by prime mover, take out the mechanical energy from the output power of prime mover, and convert it into the pressure energy of the fluid, providing pressure oil for the system. Then, where work is required, the actuator converts the fluid pressure energy into mechanical energy and outputs it to the gear pump.

 

Working principle and structure of gear oil pump

 

What role does the hydraulic gear pump play in the hydraulic system? Hydraulic gear pump is the heart of the hydraulic system, referred to as oil pump. In a hydraulic system, there must be at least one pump. Hydraulic gear pump is a kind of energy conversion device, its role is to make the flow of motion, the mechanical energy into fluid energy. Pump is the power element in the hydraulic transmission system, driven by prime mover, take out the mechanical energy from the output power of prime mover, and convert it into the pressure energy of the fluid, providing pressure oil for the system. Then, where work is required, the actuator converts the fluid pressure energy into mechanical energy and outputs it to the gear pump.

 

Hydraulic gear pump is widely used in the hydraulic system of a hydraulic pump, it is generally made of quantitative pump, according to the different structure, gear pump is divided into external gear pump and internal gear pump, and the external gear pump is the most widely used. The following external gear pump as an example to analyze the gear pump. Hydraulic gear pump mainly includes: high pressure quantitative gear pump, high pressure double gear pump, lubricating pump, chemical pump, two-way gear motor, gear pump with pressure regulating valve, gear pump with lifting valve. Working principle of the working principle and structure of the gear pump gear pump as shown in figure 3-3, it is the separation of three panel structure, three refers to the pump cover 4, 7, 8 and pump body, pump body within 7 is equipped with a pair of the same, the width and number of pump body closer to each other and the meshing gear 6, the gear with two end cover and pump body form a sealed cavity, and the gear tooth top and meshing line of the sealed cavity is divided into two parts, namely, oil pressure and oil suction cavity. The two gears are respectively fixed on the driving shaft 12 and driven shaft 15 supported by needle roller bearing with keys. The driving shaft is driven by the motor to rotate.

 

Working principle of external gear pump

 

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 pump (oil suction chamber) disengages and meshes, and the gear teeth exit between the teeth, increasing the sealing volume and forming a local vacuum. Under the action of external atmospheric pressure, the oil in the oil tank enters between the teeth through the oil suction pipeline and oil suction chamber. As the gear rotates, the oil between the suction teeth is carried to the other side and into the oil chamber. At this time the gear teeth into engagement, so that the sealing volume gradually reduced, part of the oil between the gear is extruded, forming a gear pump oil pressure process. When the gear meshes, the contact line of tooth direction separates the oil suction chamber from the oil pressure chamber and plays the role of oil distribution. When the gear pump driving gear driven by the motor constantly rotating, gear teeth out of the meshing side, due to the sealing volume increased constantly from the oil tank suction, gear teeth into the meshing side, due to the reduction of the sealing volume is constantly discharging oil, this is the working principle of gear pump. The front and rear cover of the pump and the pump body are positioned by two positioning pins (17), and fixed with 6 screws as shown in FIG. 3-3. In order to ensure the gear can rotate flexibly, and at the same time to ensure the minimum leakage, there should be an appropriate clearance (axial clearance) between the gear face and the pump cover, the axial clearance for small flow pump is 0.025~0.04mm, the large flow pump is 0.04~0.06mm. Addendum and the clearance between the pump body surface (radial clearance), because long seal belt, at the same time, addendum linear velocity and formation of shear flow and the oil leak in the opposite direction, so have less effect on the leak, here to consider the question is: when the gear is unbalanced radial force, should avoid collision of addendum and pump body wall can be slightly larger, so the radial clearance generally take 0.13 ~ 0.16 mm.

 

In order to prevent the pressure oil from leaking between the pump body and the pump cover to the outside of the pump, and reduce the tension of the compression screw, the end face on both sides of the pump body is opened with an oil seal unloading groove 16, so that the pressure oil infiltrating between the pump body and the pump cover is introduced into the oil suction chamber. Small holes in the pump cover and driven shaft act to direct the pressure oil leaking to the bearing end to the oil suction chamber of the pump to prevent oil overflow and lubricate needle roller bearing.

 

The structure of the hydraulic gear pump is as follows:

 

1- bearing outer ring 2- plug 3- roller 4- rear pump cover 5- key 6- gear 7- pump body 8- front pump cover 9- screw 10- pressure ring

 

11- sealing ring 12- driving shaft 13- key 14- drain hole 15- driven shaft 16- drain groove 17- locating pin

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