Oil-sealed vacuum pump: It is the use of oil sealed between the various moving parts of the gap, reducing the harmful space of a rotating varactor vacuum pump. This pump is usually equipped with gas ballast, it is also known as gas-town vacuum pump. According to its structural characteristics are divided into the following five types. 1, rotary vane vacuum pump: rotor with a certain eccentricity in the pump housing and pump housing fixed surface close to the surface, the rotor slot with two (or more) rotary vane, when the rotor rotation spin Slides reciprocate along their radial grooves and are always in contact with the inner wall of the pump housing. This vane rotates with the rotor to divide the pump chamber into several variable volumes. Rotary vane vacuum pump is a low vacuum pump. It can be used alone or as a foreline pump for other high or ultra-high vacuum pumps. Rotary vane pump for small and medium-sized pump, the product has been series. Rotary vane pump has a single-stage and two-stage, generally made more than two-stage, in order to obtain a higher degree of vacuum. Most of the rotary vane pump is a single working chamber structure, commonly used two radial vane, but also useful three inclined vane. Through-vane vacuum pump also has applications. 2, slide valve vacuum pump: outside the eccentric rotor is equipped with a spool, the rotor rotates the slide valve slide along the inner wall and scroll, the upper part of the slide valve spool slide valve slide in the swing, and the The pump chamber is divided into two variable volumes. Sliding valve vacuum pump suction principle and rotary vane pump similar, but the two different structures. Sliding valve vacuum pump is the use of slide valve body to change the suction chamber volume, it is called the spool pump. 3, the fixed-piece vacuum pump: pump housing equipped with an inner rotor near the eccentric rotor, the pump housing is equipped with a rotor surface is always in contact with the radial vane, when the rotor rotates, the vane can slide up and down Divide the pump chamber into two variable volumes. Fixed-chip vacuum pumping speed smaller, a single, two-stage, two-stage pump ultimate vacuum up to 10-1Pa. Pump structure is simple, long service life and easy maintenance, but because of its performance than rotary vane pump, so few have been production and application. 4, trochoidal vacuum pump: In the pump chamber eccentric equipped with a trocar-shaped rotor, which along the pump cavity wall rotation and the pump chamber is divided into two variable volume. Pump dynamic balance is good, so the pump running more stable, vibration is also small, speed can be increased, you can do small size, pumping speed, suitable for the development of large pumping speed mechanical vacuum pump. As the suction pipe is short and thick, help to improve pumping speed under low pressure. Therefore, in the low pressure range (1 ~ l00Pa) trochoidal pump pumping speed curve is better than the spool pump. Trochoidal pump rotor and pump body is a pair of conjugate tooth-shaped meshing movement, so the exhaust gas contains a certain amount of dust and small particles are not sensitive. The trochoid pump to adapt to the higher temperature of the work environment, the temperature control device can make the pump chamber to maintain a high temperature (ie trochoidal heat pump), used to extract a large amount of condensable water vapor. 5, multi-chamber rotary vane vacuum pump: In a pump casing mounted in parallel by the same motor-driven multiple independent studio rotary vane vacuum pump.