A vacuum pump is a device or device that uses a mechanical, physical, chemical, or physicochemical method to evacuate a pumped container to obtain a vacuum. In general, a vacuum pump is a device that uses various methods to improve, create, and maintain a vacuum in an enclosed space.
According to the working principle of the vacuum pump, the vacuum pump can basically be divided into two types, namely, a gas trap pump and a gas transfer pump. It is widely used in metallurgy, chemical, food, electronic coating and other industries.
Structural features
(1) Overall structure of the pump
The arrangement of the pump body of the vacuum pump determines the overall structure of the pump.
The vertical structure of the inlet and exhaust ports is horizontally set, and it is convenient to assemble and connect the pipelines. However, the pump has a high center of gravity and poor stability at high speeds, so this type is mostly used for small pumps.
The inlet of the horizontal pump is on the top and the outlet is on the bottom. Sometimes it is convenient to install and connect the piping of the vacuum system, and the exhaust port can be taken out from the horizontal direction, that is, the direction of intake and exhaust is perpendicular to each other. At this time, the exhaust port may be opened from the left or the right direction, except for one end of the exhaust pipe, and 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 use this type of structure.
The two rotor shafts of the pump are mounted perpendicular to the horizontal. The structure assembly gap is easy to control, the rotor assembly is convenient, and the pump footprint is small. However, the pump has a high center of gravity and the gears are inconvenient to assemble and disassemble, and the lubrication mechanism is relatively complicated.
(2) Pump transmission mode
The two rotors of the vacuum pump are operated synchronously by a pair of high precision gears. The drive shaft is coupled to the motor via a coupling. There are two main types of transmission structure: one is that the motor and the gear are placed on the same side of the rotor. The driven rotor is directly transmitted by the motor end gear, so that the torsional deformation of the active rotor shaft is small, and the gap between the two rotors is not changed due to the large torsional deformation of the driving shaft, so the gap between the rotors is operated. Uniform in the process. The biggest disadvantage of this type of transmission is: a. There are three bearings on the drive shaft, which increases the difficulty of processing and assembly of the pump, and the disassembly and adjustment of the gear is inconvenient; b. The overall structure is not uniform, the center of gravity of the pump is biased toward the motor and gear One side of the box.
Features
(1) A large pumping speed over a wide pressure range;
(2) The rotor has good geometric symmetry, so the vibration is small and the operation is stable. There is a gap between the rotor and between the rotor and the casing, no lubrication, and the friction loss is small, which can greatly reduce the driving power, thereby achieving a higher rotational speed;
(3) Oil seal and lubrication are not required in the pump chamber, which can reduce the pollution of the vacuum system by oil vapor;
(4) There is no compression in the pump chamber, no exhaust valve. The structure is simple and compact, and is insensitive to dust and water vapor in the pumped gas;
(5) The compression is relatively low, and the effect on hydrogen gas pumping is poor;
(6) The surface of the rotor is a curved cylinder with a complicated shape, which is difficult to process and inspect.
