1. Whether variable is required
According to different structures, hydraulic pumps can be categorized as vane pumps, gear pumps, piston pumps and screw pumps (not commonly used). According to whether the flow rate changes, can be divided into quantitative pumps and variable pumps.
Constant speed, choose quantitative pumps, gear pumps and double-acting vane pumps; if the pump flow is required to be variable, you can choose single-acting vane pumps and piston pumps.
2. System pressure
Selection of hydraulic pumps, should be considered so that the pump has a certain pressure reserve, the rated working pressure of the hydraulic pump should be higher than the system working pressure of 10% -20%.
Generally speaking, in low-pressure (high pressure less than 7Mpa) conditions, what type of pump can be used. High-pressure (high pressure less than 60Mpa) conditions should be selected piston pumps, gear pumps in the medium-pressure (high pressure less than 32Mpa) conditions used more. Vane pumps, screw pumps in low-pressure applications more economical.
3. Working environment
Resistance to pollutants, of which the gear pump has the best anti-pollution ability, followed by vane pumps. Piston pumps require the highest cleanliness of oil.
4. Noise
Indicators in the same working conditions, the noise generated by the hydraulic pump varies with the type of pump. Hydraulic pumps produce noise with the pressure, displacement and rise, but also with the increase in speed and rise.
5. Efficiency of hydraulic pump efficiency is generally affected by the following factors: size, geometric clearance and precision of the parts in the hydraulic pump; viscosity and performance of the fluid; operating pressure and speed.
5. Efficiency
The efficiency of hydraulic pumps is generally affected by the following factors: size, geometric clearance and precision of the parts in the hydraulic pump; viscosity and performance of the fluid; operating pressure and speed. In order to get high volumetric efficiency, when choosing hydraulic pump, you must know the allowable limit of the internal parts of the hydraulic pump.
Generally speaking, axial piston pumps have the highest total efficiency, followed by vane pumps and finally gear pumps. The same structure of the pump, the displacement of the pump high total efficiency; The same displacement of the pump in the rated working condition of the highest total efficiency.
6. Application
Vane pumps are generally used only in non-regulating hydraulic systems, such as machine tools, hydraulic presses, vehicles, construction machinery and plastic injection molding machines in the hydraulic system.
Gear pumps are mostly used in machine tools, engineering machinery, mining machinery, agricultural machinery.
Piston pumps, especially axial piston pumps, are widely used in the requirements of high pressure, high flow and the need to regulate the high-power hydraulic system, such as forging machinery, transportation machinery, mining machinery, metallurgical machinery, ships, aircraft and so on.
7. Economic cost
The cost of hydraulic pumps depends on many factors, the most important is the complexity of the structure varies from pump to pump.
In general, gear pumps cost the least, internal gear pumps are more expensive than vane pumps, screw pumps are more expensive than internal gear pumps and vane pumps, piston pumps are more expensive than other pumps.
Selection of hydraulic pumps, in addition to considering the above factors, the designer of the hydraulic system and the use of maintenance personnel should also take into account other factors, such as the safety pressure, the maximum operating pressure of the system, the compatibility of the entire system and other basic factors. At the same time, the manufacturer's reputation, maintenance and supply of spare parts, etc., is also the selection of hydraulic pumps need to be considered.
