Vacuum Pump - Structural Characteristics

What is the structural specification of a vacuum pump? Below we will provide you with a detailed explanation.
(1) Overall structural type of pump
The layout structure of the vacuum pump body determines the overall structure of the pump.
The vertical structure of the intake and exhaust ports is horizontally arranged, making assembly and connection of pipelines more convenient. But the center of gravity of the pump is relatively high, and its stability is poor during high-speed operation, so this type is mostly used for small pumps.
The intake port of the horizontal pump is located above and the exhaust port is located below. Sometimes, for the convenience of installing and connecting vacuum system pipelines, the exhaust port can be connected horizontally, meaning that the inlet and outlet directions are perpendicular to each other. At this point, the exhaust port can be opened from both left and right directions, except for one end of the exhaust pipeline, the other end can be blocked or connected to a bypass valve. This pump structure has a low center of gravity and good stability during high-speed operation. This structure is commonly used for large and medium-sized pumps.
The two rotor shafts of the pump are installed perpendicular to the horizontal plane. This structure has easy control of assembly clearance, convenient rotor assembly, and small pump footprint. However, the center of gravity of the pump is relatively high and the gear disassembly is inconvenient, and the lubrication mechanism is also relatively complex.
(2) Pump transmission mode
The two rotors of the vacuum pump operate relatively synchronously through a pair of high-precision gears. The driving shaft is connected to the motor through a coupling. There are mainly two types of transmission structure layout: one is that the electric motor and gear are placed on the same side of the rotor as shown in the figure. The driven rotor is directly driven by the motor end gear, so that the torsional deformation of the active rotor shaft is small, and the gap between the two rotors will not change due to the large torsional deformation of the active shaft, so that the gap between the rotors is uniform during operation. The biggest disadvantage of this transmission method is that: a. there are three bearings on the driving shaft, which increases the difficulty of pump processing and assembly, and the disassembly and adjustment of gears are also inconvenient; b. The overall structure is uneven, and the center of gravity of the pump leans towards the side of the motor and gearbox.
characteristic
(1) There is a large pumping speed within a wide pressure range;
(2) The rotor has good geometric symmetry, resulting in low vibration and smooth operation. There are gaps between the rotors and between the rotor and the shell, which do not require lubrication and have small friction losses, which can greatly reduce driving power and achieve higher speeds;
(3) The pump chamber does not require oil sealing and lubrication, which can reduce the pollution of oil vapor on the vacuum system;
(4) There is no compression or exhaust valve in the pump chamber. Simple and compact structure, insensitive to dust and water vapor in the extracted gas;
(5) Low compression ratio, poor hydrogen extraction effect;
(6) The surface of the rotor is a complex curved cylindrical surface, which is difficult to process and inspect.