As the heart of the hydraulic system, the hydraulic pump provides power for the hydraulic system, and its performance plays a key role in the normal operation of the system. This paper mainly introduces the structure and principle of gear pump, vane pump and plunger pump.
1 Gear pump
Compared with the other two kinds of pumps, gear pump is characterized by simple structure, low price, small size, light weight, insensitive to oil pollution, good self-priming, reliable work. The disadvantage is that the noise is large, the flow fluctuation is large, and the displacement is not variable. Gear pumps are widely used, such as in construction machinery, mining machinery, construction machinery and other fields. Gear pump is divided into internal and external meshing two structural forms.
The structure of gear pump mainly includes: main and driven gear, drive shaft, pump body, side plate and so on. The meshing line of the two gears divides the pump body into two chambers: the oil suction chamber and the oil pressure chamber. The following figure shows the working principle of the external gear pump.
Through the meshing of two gears, the volume of the right oil chamber increases to form negative pressure for oil absorption, and the volume of the left side decreases for oil discharge. The driving gear rotates continuously, so that the pump continuously absorbs oil from the tank and drains oil to the system.
2 vane pump
Vane pump has single acting and double acting two categories, double acting vane pump for quantitative pump, single acting vane pump can achieve variable. Vane pump is widely used in machine tools, engineering machinery, metallurgical equipment and other fields. It is characterized by: small flow pulsation, small noise, smooth operation, but the cleanliness of the oil requirements are high.
The main structure of vane pump is: stator, rotor, blade, valve plate and so on. The following figure shows the principle of double-acting vane pump, and the rotor completes two oil suction and two oil discharge.
3 Plunger pump
Plunger pump is through the reciprocating movement of the plunger to make the volume change in the closed chamber to achieve oil absorption and oil discharge, is characterized by small leakage, high volume efficiency, widely used in high pressure system. The piston pump includes axial piston pump and radial piston pump, and the axial piston pump has two categories: swash plate type and inclined shaft type.
The structure of the plunger pump is complex, the technical content is high, the variable mode is diverse, and the material, process and heat treatment are relatively high. At present, the technical level of China's plunger pump is still a big gap compared with foreign countries. The principle of axial piston pump with swash plate is introduced by taking the common axial piston pump as an example.
The main structure of swash plate axial piston pump is: pump body, plunger, swash plate, cylinder block, valve plate and so on. The following diagram shows the structure of the swash plate axial piston pump. The cylinder block and plunger rotate under the action of the drive shaft. During the downward movement of the plunger, the volume of the chamber decreases continuously to realize oil discharge. The volume increases during upward movement to achieve oil absorption.
