Working Principle Of Hydraulic Pump

Working principle of hydraulic pump
The working principle of the hydraulic pump: the movement brings about the change in the volume of the pump cavity, thereby compressing the fluid so that the fluid has pressure energy. The condition that must be provided is that the pump cavity has a sealed volume change.

The hydraulic pump can be divided into four types according to the working principle, as follows.

1.Gear pump
Smaller size, simpler structure, less stringent requirements on oil cleanliness, and cheaper price; but the pump shaft is subject to unbalanced forces, severe wear, and large leaks. External gear pump: When the gear rotates, in the A cavity, the volume gradually increases due to the disengagement of the gear teeth, forming a vacuum to suck oil from the oil tank. As the gear rotates, the oil filled in the tooth groove is brought to the B cavity. The volume of the cavity is gradually reduced due to the meshing of the gear teeth, and the hydraulic oil is discharged. The closed volume formed by the teeth and the pump casing is used to complete the function of the pump.

2.Vane pump
Divided into double acting vane pump and single acting vane pump. This kind of pump has even flow, stable operation, low noise, higher working pressure and volumetric efficiency than gear pump, and more complex structure than gear pump. When the rotor rotates, the tip of the blade abuts on the inner surface of the stator under the action of centrifugal force and pressure oil. In this way, the working volume formed by the two blades and the inner surface of the rotor and the stator is first sucked from small to large and then drained from large to small. When the blades rotate once, the oil is absorbed twice and the oil is discharged twice. The volume change between the blades completes the function of the pump.

3.Plunger pump
High volume efficiency, small leakage, can work under high pressure, mostly used in high-power hydraulic systems; but the structure is complex, the material and processing accuracy requirements are high, the price is expensive, and the oil cleanliness requirements are high. Generally, the plunger pump is used when the gear pump and vane pump cannot meet the requirements. There are some other forms of hydraulic pumps, such as screw pumps, but the applications are not as common as the three above. The plunger pump is composed of a cylinder body and a plunger. The plunger reciprocates in the cylinder body, sucks oil when the working volume increases, and drains oil when the working volume decreases. The radial load of the oil distribution on the end face is used to balance the large bearing on the outer periphery of the cylinder to limit the tilt of the cylinder. The transmission shaft is only used to transfer torque and the shaft diameter is small. Due to the tilting moment of the cylinder body, the manufacturing accuracy is required to be high, otherwise the flow plate may be easily damaged.

4.Screw pump
One driving screw and two driven screws mesh with each other, and the meshing line of the three screws divides the spiral groove into a plurality of sealed volumes. When the screw rotates, this sealed volume moves in the axial direction to realize oil absorption and oil discharge. The use of the internal volume of the screw groove moves, resulting in an invariable function of the pump. No flow pulsation. Radial load is smaller than that of the twin screw type.

Post time: Feb-14-2020