Structural features of the vacuum pump

（1）The overall structure of the pump
The arrangement structure of the pump body of the vacuum pump determines the overall structure of the pump.
The intake and exhaust ports of the vertical structure are set horizontally, and it is convenient to assemble and connect the pipelines. However, the center of gravity of the pump is high, and the stability is poor at high speed, so this type is mostly used for small pumps.
The inlet port of the horizontal pump is on the top and the exhaust port is on the bottom. Sometimes, in order to facilitate the installation and connection of the vacuum system pipeline, the exhaust port can be connected from the horizontal direction, that is, the inlet and exhaust directions are perpendicular to each other. At this time, the exhaust port can be opened from the left or right direction, except for one end of the exhaust pipe, the other end is blocked or connected to the bypass valve. This pump has a low center of gravity and good stability at high speeds. Generally, large and medium-sized pumps mostly use this structure.
The two rotor shafts of the pump are mounted perpendicular to the horizontal plane. This structure is easy to control the assembly clearance, easy to assemble the rotor, and the pump occupies a small area. However, the center of gravity of the pump is high, the gear is inconvenient to disassemble and assemble, and the lubrication mechanism is relatively complex.
（2）The transmission mode of the pump
The two rotors of the vacuum pump are operated in relative synchrony by means of a pair of high-precision gears. The drive shaft is connected to the motor by means of a coupling. There are two main types in the transmission structure arrangement: one is that the motor and gear are placed on the same side of the rotor, as shown in the figure. The driven rotor is driven by the motor end gear directly, so that the torsional deformation of the driving rotor shaft is small, and the gap between the two rotors will not change due to the large torsional deformation of the driving shaft, so the gap between the rotors is uniform in the process of operation. The biggest disadvantage of this transmission mode is: a. there are three bearings on the driving shaft, which increases the difficulty of processing and assembly of the pump, and the disassembly and adjustment of the gear is also inconvenient; b. the overall structure is uneven, and the center of gravity of the pump is biased to the side of the motor and the gearbox.