Views:89 Author:Site Editor Publish Time: 2020-05-07 Origin:Site
The rotary pump is a mechanism that converts mechanical energy into pressure energy. The common feature of its work is to absorb and discharge oil by changing the volume of the working chamber. To ensure continuous operation of the rotary pump, the working chamber should be able to increase and decrease periodically. When the working chamber increases, it should be connected to the oil suction port. When the oil suction chamber expands to the limit position, it must first be disconnected from the oil suction chamber, and then communicated with the pressure oil chamber. According to the shape and movement mode of the main moving components of the rotary pump, there are gear pumps, screw pumps, vane pumps and so on.
There are many kinds of rotary pumps, which can be divided into gear pump, screw pump, sliding vane pump, cam pump, roots pump, eccentric rotor pump, three-rotor pump, cycloidal rotor pump, radial piston pump and axial piston pump according to different rotor types. Most of them have the following characteristics.
1. Their main working parts are the pump casing and the rotor (such as gears and screw rods). The shape of the rotor is uneven. When they rotate, they form a lot of small empty volume with the inner wall of pump casing and inhale the liquid, which is finally squeezed to the discharge pipe and output.
2. The rotor rotates without impact, and the number of revolutions can be high. Therefore, its structure is compact and its volume is smaller than reciprocating pump.
3. The discharge pressure is smaller than the reciprocating pump, the flow rate and efficiency are lower, so it is only suitable for conveying small amounts of liquid.
The vane pump belongs to the rotary volumetric pump. It relies on the change of the working volume to achieve the suction and discharge of liquid. It is generally used as an oil pump. The vane pump is divided into single acting vane pump and double acting vane pump according to the number of suction and discharge per revolution of its working volume.
When the rotor rotates once, and each working volume completes one suction and discharge work, it is called a single-acting vane pump. The inner surface of the stator is circular, and the rotor driven by the prime mover is eccentrically installed in the stator. When the rotor rotates, the top of the blade will slide against the stator due to the centrifugal force and the hydraulic pressure from the discharge chamber to the root of the blade. When the rotor rotates counterclockwise, the blade on the right will gradually extend outward from the rotor slot, the volume between each two blades gradually increases, and the oil is sucked through the arc-shaped oil suction window. When the blade turns to the left, the blade gradually shrinks into the groove, and the volume between the blades gradually decreases, so the oil is squeezed and discharged from the arc-shaped oil discharge window. This type of pump is also called an unbalanced vane pump because the rotor is affected by the oil pressure difference between the suction and discharge chambers, and there is a radial imbalance force, which causes the pump shaft to be subjected to alternating loads. It is not suitable to work under high pressure. However, its structure is simple, lightweight, and easy to manufacture, so it is widely used in low-pressure hydraulic systems.
The rotor rotates once, and each working volume completes two suction and discharge work, which is called a double-acting vane pump. The inner surface of the stator is formed by connecting two large arcs, two small arcs and four transition curves. In the process of one revolution of the rotor, the volume between the blades gradually increases as it sweeps through the suction transition curved surface, and sucks oil from the oil suction window. When sweeping through the discharge transition surface, the volume between the blades gradually decreases, and the oil is squeezed and discharged from the oil discharge window.
The combined use of rotary pump and valve can transport fluid with high viscosity, such as oily materials. Due to the small gap of the rotary pump, it is generally not suitable to transport suspensions containing solids.