The hydraulic pump is the power component of the hydraulic system. It is driven by the engine or electric motor to suck oil from the hydraulic oil tank, form the pressure oil to discharge, and send it to the actuator. Hydraulic pumps are divided into gear pumps, plunger pumps, vane pumps and screw pumps according to their structure. The following editor will introduce the types of hydraulic pumps and the working principle of hydraulic pumps.
Types of hydraulic pumps
1. Gear pump: Smaller in size, simpler in structure, less strict on the cleanliness of the oil, and cheaper in price; but the pump shaft is severely worn by unbalanced forces, and the leakage is relatively large.
2. Vane pump: It is divided into double-acting vane pump and single-acting vane pump. This pump has uniform flow rate, stable operation, low noise, higher working pressure and volume power than gear pump, and more complex structure than gear pump.
3. Plunger pump: high volumetric power, small leakage, can work under high pressure, and is mostly used in high-power hydraulic systems; but the structure is complex, the requirements for materials and processing accuracy are high, the price is expensive, and the requirements for oil cleanliness are high.
How hydraulic pumps work
The pump is an energy conversion device that converts the rotational mechanical energy of the motor into hydraulic energy for output. Hydraulic pumps work on the principle of changing the sealed volume, so they are generally called volumetric hydraulic pumps. Figure 2-l shows the working principle of a single-piston hydraulic pump. The plunger 2 in the figure is installed in A sealed volume a is formed in the cylinder body 3, and the plunger is pressed against the eccentric wheel 1 under the action of the spring 4. The prime mover drives the eccentric wheel 1 to rotate to make the plunger 2 reciprocate, so that the size of the sealed volume a is changed periodically. When a changes from small to large, a certain vacuum is formed, so that the oil in the oil tank, under the action of atmospheric pressure, pushes the check valve 6 through the oil suction pipe and enters the oil chamber a to complete the oil suction; on the contrary, when a changes from large to small, the oil in the chamber a The oil that has been sucked up will push open the one-way valve 5 and flow into the system to stop the oil pressure. In this way, the hydraulic pump converts the mechanical energy input by the prime mover into the pressure energy of the liquid. The prime mover drives the eccentric wheel to rotate continuously, and the hydraulic pump continuously absorbs and presses oil.
Characteristics of hydraulic pumps
1. There are several sealed spaces that can be changed periodically. The output flow of the pump is directly proportional to the volume change of this space and the number of changes per unit time, and has nothing to do with other factors.
2. The certain pressure of the liquid in the fuel tank must be equal to or greater than the atmospheric pressure. This is the external condition that the displacement hydraulic pump can suck oil. Therefore, in order to ensure that the hydraulic pump can absorb oil normally, the fuel tank must be connected to the atmosphere, or a closed sub-fuel tank must be selected.
3. Have corresponding flow distribution organization. Separate the suction box and the liquid discharge box to ensure that the hydraulic pump can suck and discharge liquid regularly and continuously.
