The hydraulic pump is one of the key components of a hydraulic system. Understanding the principle of hydraulic pumps is an essential step to building hydraulic systems. This article will provide an in-depth analysis of how common hydraulic pumps work and the key factors that influence their efficiency.
What is Hydraulic Pump
Hydraulic pump is a mechanical device, which can convert mechanical power into hydraulic energy. Hydraulic pumps mainly rely on external power sources (electric motors or internal combustion engines) to draw in fluid. Then through the internal motion, hydraulic pumps create pressure to pump the fluid into the hydraulic system.
Types of Hydraulic Pumps and How do They Work
Hydraulic pumps are divided into positive-displacement pumps and non-positive-displacement pumps. The majority of hydraulic pumps in hydraulic systems belong to the positive-displacement pumps, also known as hydrostatic pumps. Based on the differences in the rotating components of hydraulic pumps, they can be classified into three basic types: hydraulic vane pumps, hydraulic gear pumps, and hydraulic piston pumps.
Every hydraulic pump works under the drive of the prime mover. The gears, vanes, and other components of the hydraulic pump are driven, thereby generating fluid flow. When vacuum enters the chamber through the inlet valve, pressure builds up inside the hydraulic pump. Then pressure forces fluid to flow out through the outlet valve. The followings are introduction to the working principles of specific types of hydraulic pumps:
How do hydraulic gear pumps work
Among the three basic types, hydraulic gear pumps have the lowest volumetric efficiency, but they offer the advantages of simplicity and cost effectiveness. Hydraulic gear pumps operate through the rotation and meshing of two internal gears, divided into external gear pumps and internal gear pumps.
The two gears in an external gear pump are not driven simultaneously. One gear drives the other to rotate under external motivation. When the gears disengage, pressure is produced, forcing fluid into the internal chamber. Upon re-engagement, the fluid is transported to the outlet and expelled.
The internal gear consists of an outer gear and an inner gear, with a crescent-shaped internal space formed between the two gears. By the difference in tooth count and rotational speed between the two gears, pressure is generated to drive fluid flow in and out.
Generally speaking, internal gear pumps are more complex to manufacture and tend to have a higher price than external gear pumps. However, internal gear pumps offer excellent quiet operation and process superior wear resistance and durability. If your budget allows, an internal gear pump represents a highly cost effective choice.
How do hydraulic vane pumps work
A hydraulic vane pump is a vane pump used within a hydraulic drive system that is typically driven by an electric motor or engine. It creates different pressures as these vanes move by turning, in turn pulling fluid in or discharging it.
There are variable displacement and fixed displacement type vane pumps. The fluid flow of the variable displacement pump can be adjusted according to actual needs in each cycle, while for the fixed displacement pump, the fluid flow each cycle is always constant. Additionally, there exists a specialized type known as a pressure-compensated vane pump. It provides pressure when required to enhance the efficiency of the hydraulic pump.
Hydraulic vane pumps have high volumetric efficiency and they are quiet. If you need a pump for low-viscosity fluids, the vane pump is an excellent choice due to their high efficiency with such fluids. Its maintenance is straightforward, helping to reduce your long-term costs.
How do hydraulic piston pumps work
Hydraulic piston pumps are commonly used in large oil fields, ships, construction, and other fields. It is a hydraulic pump composed of a piston and cylinder assembly, divided into axial and radial types, and it has excellent sealing performance. Both types of plunger pumps can be used for fixed displacement or variable displacement. When employed for variable displacement, they are often larger in size.
The pistons in an axial piston pump are arranged along the central axis, parallel to the drive shaft of the pump. Common types include swashplate type and swashplate type. However, in radial pistons, the pistons are arranged in the opposite manner, positioned perpendicular to the central shaft. Radial pistons typically have higher rated pressures than axial pistons and offer greater overall efficiency. If you need to choose between the two, radial pistons clearly have the advantage.
Factors Affecting Hydraulic Pump Efficiency
The efficiency of a hydraulic pump plays a significant role in the proper operation of the entire hydraulic system. There are numerous factors that affect the efficiency of hydraulic pumps. Below are some methods for expressing hydraulic pump efficiency and their influencing factors:
Volumetric Efficiency
Volume efficiency is closely related to the fluid flow rate that a hydraulic pump can handle. If the volumetric efficiency is too low, fluid leakage may have occurred. This is typically caused by wear in the hydraulic pump, contamination, or the use of an unsuitable fluid.
Mechanical Efficiency
The primary factors affecting mechanical efficiency include wear of the hydraulic pump bearing components, misalignment of hydraulic pump parts, and incorrect fluid selection. Reduced mechanical efficiency means the hydraulic pump must expend more energy to counteract issues such as friction. Therefore, you need to regularly inspect and replace the components of the hydraulic pump to improve its mechanical efficiency.
Overall Efficiency
The overall efficiency of a hydraulic pump is influenced by comprehensive factors, including pump types, conditions and so on. Overall efficiency can be calculated from volumetric efficiency and mechanical efficiency. In daily working, you can use many types of methods to enhance the overall efficiency of hydraulic pumps. But the primary approach is to prevent wear on the hydraulic pump and contamination of the fluid. Proper maintenance can significantly improve pump efficiency.
Conclusion
Hydraulic pumps are vital industrial components that are indispensable in hydraulic systems. This article has provided you with comprehensive information about them. If you have further questions, feel free to contact us for professional hydraulic pump solutions.
FAQ
1. What is the difference between a hydraulic pump and a hydraulic motor?
While hydraulic motors and hydraulic pumps both transform energy, these two components are different. A hydraulic pump is a device that can change the mechanical energy into hydraulic energy, and the hydraulic pumps usually only move in a single direction. Hydraulic motors, in contrast, convert hydraulic energy into mechanical energy and are equally reversible. Moreover, their usage does not coincide. However, hydraulic motors and hydraulic pumps are constructed and functioned in basically the same manners.
2. Is the gear pump noisy?
Gear pumps have been modified through advanced technology to achieve silent operation. Precise gear pumps minimize tolerances to the greatest extent possible, enabling a tighter fit between their gears. At the same time, the design of certain split gears can also help gear pumps reduce vibration and achieve a quiet operation.
3. How to maintain a hydraulic pump?
Most causes of hydraulic pump performance degradation stem from fluid blockage or contamination. During daily use, pay attention to the condition of the fluid and inspect the filter screen promptly. If conditions permit, installing a pressure sensor can help you better maintain the hydraulic pump by detecting safety hazards that are difficult to observe with the naked eye.
4. How to choose a suitable hydraulic pump？
Hydraulic pumps have various rated pressures, so you need to know the pressure that the hydraulic pump you need is required to reach. Depending on the type of fluid, you should choose the appropriate hydraulic pump to ensure the compatibility, and analyze the application scenarios of hydraulic pumps based on your project requirements and select the appropriate materials and types. Hydraulic pumps with large capacities and complex construction always have a higher price, but they also offer correspondingly higher safety factors. You can select the most cost-effective options within your budget.
