Rotary vane vacuum pump (Rotary vane pump) is an oil-sealed mechanical vacuum pump. Its working pressure ranges from 101 325 to 1.33 x 10-2 (Pa) and belongs to low vacuum pump. It can be used alone or as the front pump of other high vacuum pumps or ultra-high vacuum pumps. It has been widely used in metallurgy, machinery, military industry, electronics, chemical industry, light industry, petroleum, medicine and other production and scientific research departments.

Rotary vane pump can extract the dry gas from the sealed container, and a certain amount of condensable gas can also be extracted if a gas ballast device is attached. But it is not suitable for extracting gases with excessive oxygen, corrosive to metals, chemical reaction to pump oil and particulate dust.

Rotary vane pump is one of the most basic vacuum acquisition equipment in vacuum technology. Rotary vane pumps are mostly small and medium-sized pumps. There are two kinds of rotary vane pumps: single-stage pump and double-stage pump. The so-called two-stage structure is to connect two single-stage pumps in series. Generally, it is made into two stages to obtain higher vacuum. The relationship between the pumping speed and the inlet pressure of the rotary vane pump is as follows: under the inlet pressure of 133 3a, 1.33 Pa and 1.33 x 10-1 (Pa), the pumping speed of the rotary vane pump shall not be lower than 95%, 50% and 20% of the nominal pumping speed of the pump, respectively.

The diagram shows the working principle of the rotary vane pump. Rotary vane pump is mainly composed of pump body, rotor, rotary vane, end cover, spring and so on. A rotor is eccentrically installed in the cavity of the rotary vane pump. The outer circle of the rotor is tangent to the inner surface of the pump cavity (there is a small gap between them). Two rotary vanes with springs are installed in the rotor groove. When rotating, centrifugal force and spring tension keep the top of the rotor in contact with the inner wall of the pump chamber. Rotor rotation drives the blade to slide along the inner wall of the pump chamber.

The two rotating vanes divide the crescent-shaped space enclosed by the rotor, pump chamber and two end caps into three parts: A, B and C, as shown in the figure. When the rotor rotates in the direction of arrow, the volume of space A connected with the suction port increases gradually and is in the process of suction. The volume of space C connected with the exhaust port is gradually reduced and is in the process of exhaust. The volume of space B in the middle is also gradually decreasing and is in the process of compression. Because the volume of space A increases gradually (i.e. expands), the pressure of gas decreases, and the pressure of gas outside the inlet of the pump is stronger than that inside space A, the gas is inhaled. When space A is isolated from the suction port, that is to say, when it moves to space B, the gas begins to be compressed, the volume gradually reduces, and finally communicates with the exhaust port. When the compressed gas exceeds the exhaust pressure, the exhaust valve is pushed open by the compressed gas, and the gas is discharged into the atmosphere through the oil layer in the tank. Continuous operation of the pump achieves the purpose of continuous pumping. If the exhausted gas passes through the airway and transfers to another stage (low vacuum stage), it is pumped out by the low vacuum stage, and then compressed by the low vacuum stage and discharged into the atmosphere, a two-stage pump is formed. At this time, the total compression ratio is borne by two stages, thus increasing the ultimate vacuum.