The hydraulic pump is the power part of the hydraulic system. It is driven by the engine or motor and absorbs oil from the hydraulic oil tank to form a part that discharges pressure oil and delivers it to the executive part. The hydraulic pump is divided into gear pump, plunger pump, vane pump and screw pump. The following small series introduce the types of hydraulic pumps and their working principles.

Type of hydraulic pump.

1. Gear pump: small in size, simple in structure, and not strict in oil cleanliness, Cycloidal motor of cotton picker cheapness; However, the pump shaft is severely worn due to unbalanced force, resulting in large leakage.

2. Vane pump: divided into double acting vane pump and single acting vane pump. The pump has uniform flow, stable operation, low noise, higher working pressure and volume power than gear pump, and more disordered structure than gear pump.

3. Piston pump: large volume power, small leakage, can work under high pressure, and is mostly used for high-power hydraulic systems; however Ningbo cycloid motor The structure is messy, the material and processing precision are required to be high, the quotation is expensive, and the oil cleanliness is required to be high.

Operating principle of hydraulic pump.

The pump is an energy conversion device, which converts the rotating mechanical energy of the motor into hydraulic energy output. The working principle of the hydraulic pump is to change the sealing volume, so it is generally called a positive displacement hydraulic pump. Schematic diagram of single plunger hydraulic pump. In this figure, the plunger 2 is installed in the cylinder block 3 to form the sealing volume A, which is always pressed against the eccentric 1 under the action of the tension spring 4. The prime mover drives the eccentric wheel 1 to rotate, making the plunger 2 reciprocate, and the size of the sealing volume A changes periodically. When a changes from small to large, a certain vacuum is formed to make the oil in the oil tank push the check valve 6 into the oil chamber a through the oil suction pipe under the effect of atmospheric pressure, and end the oil suction; conversely, Cycloidal motor parameters When A changes from large to small, the oil sucked into cavity A will push open the check valve 5 and flow into the system to end oil pressure. In this way, the hydraulic pump converts the mechanical energy input by the prime mover into the pressure energy of the liquid, and the prime mover drives the eccentric wheel to rotate continuously, so that the hydraulic pump continuously absorbs and presses oil.

Characteristics of the hydraulic pump.

1. Several sealed spaces can be replaced regularly. The output flow of the pump is proportional to the volume change of this space and the number of changes per unit time, independent of other factors.

2. The liquid with a certain pressure in the oil tank must be equal to or greater than atmospheric pressure. This is the external condition that the positive displacement hydraulic pump can absorb oil. Therefore, in order to ensure that the hydraulic pump can absorb oil normally, the oil tank needs to be connected to the atmosphere, or select a sealed sub charging oil tank.

3. There are corresponding distribution organizations. Separate the suction tank from the discharge tank to ensure that the hydraulic pump regularly absorbs and discharges liquid.