Dry claw vacuum pump of structure and working principle
Dried claw vacuum is an early emergence of a pump, the world’s first dry claw vacuum pump in 1985 in Japan to market, applied in Japan at that time the rapid development of the semiconductor industry. As one of the earliest dry vacuum pumps on the market, it has many unique advantages in addition to having no oil or any medium in the pump chamber and no oil return after cleaning
(1) the rotor pair is suspended in the pump cavity, between the rotor pair and the pump cavity are frictionless;
(2) can directly exhaust the atmosphere independently, and can work under high pressure for a long time continuous;
(3) can completely remove condensable gases (such as water vapor, alcohol and gasoline, etc.);
(4) can extract corrosive, toxic, radioactive and inflammable and explosive gases;
(5) can do gas transmission pump use, compression ratio is good.
(6) can remove the metal dust and mineral particles carried by the gas.
Dry claw vacuum pump is also used as liquid ring pump, water jet pump substitute product has been successfully applied in VD/VOD, which has obtained good economic and environmental benefits: it can not only exceed 90% operation cost, but also greatly reduce the emission of dust. In addition, dry claw vacuum pump is widely used in chemical industry, nuclear industry, thin film, instrument, medicine, food and other fields.
Dry claw vacuum pump is composed of rotor, pump body, drive shaft, driven shaft, suction port, exhaust port and baffle, etc. The working process is: when the two rotors rotate in the direction of the arrow, the suction mouth is connected with the pump chamber. The volume of the pump chamber becomes large and the suction. When the rotor closes the intake, the intake is complete. After the pump chamber becomes smaller and compressed gas, when the exhaust port is opened, the pump chamber exhaust; When the vent is closed, exhaust is finished. Work in cycles.
Below will elaborate the characteristic of vertical structure in detail.
Compared with the horizontal dry claw vacuum pump, the vertical structure has the following advantages:
(1) The compact size of the motor layout is more reasonable, the external size is smaller;
(2) Easy to install, easy to adjust the radial and axial clearance (the axial clearance can be adjusted with gasket if necessary)
(3) Because of the use of transition gear, the motor can be more stable transmission of power, reduce vibration and noise;
(4) the vertical pump inlet in the upper end of the pump, and the exhaust at the bottom of the pump, this structure is very conducive to exhaust. Because of the buffer cavity structure, the intake and exhaust process can be carried out more smoothly, avoiding the impact of airflow;
(5) Adopt vertical structure, make the whole pump shape beautiful, and easy to use and transport.
But the vertical structure also has some disadvantages, mainly as follows:
(1) higher than the horizontal pump, high speed operation may make the system unstable;
(2) the lower part of the pump bearing bear a large force. Easy to damage.
Pump body structure
There are generally two types of pump body structure, that is, the integral type and splicing type. Splice type pump body is to connect the pump body at all levels and the separator with a long medium rod, and the pump body at all levels and the separator as well as the upper and lower bearing pedestal by ensuring its sealing. The use of part splicing into a whole structure is mainly considered from the point of view of easy assembly. If the whole pump cavity structure is used, the rotor can not be assembled. Even if the assembly can be realized, it is impossible to adjust the working room that must be guaranteed between rotor and rotor, rotor and pump cavity. Therefore, in order to ensure the normal assembly of the rotor, it is recommended to adopt the structure mode of part and split-together into a whole.
Dry claw vacuum pump is mainly developed for the development of semiconductor industry. Due to the requirements of its manufacturing process, the semiconductor industry needs to create a clean vacuum atmosphere without pollution. However, many traditional vacuum pumps cannot meet the requirements of the semiconductor industry well due to their own limited conditions. The manufacturing cost of dry claw vacuum pump is a little higher, and the machining precision is higher, but its external compression has internal compression, which improves the pumping rate.
The main body of the pump is equipped with gears, motors and gas purification equipment. There are anti-reflux-proof valves at the entrance, retention valves at the exit, electrical monitoring and warning equipment. The second, third and fourth levels all have the inlet of purifying gas to improve the pumped medium so that it can pass through the pump chamber smoothly. If there is no such need, the purified gas can be adjusted separately with three flow meters, which are independent of each other to ensure the saving of inert gas. The flow child can be fine-tuned by using three solenoid valves. Inlet anti-reflux valves can separate the pumping vessel from the pump chamber. Outlet interceptor valves can close the pump outlet and pass the pump to purify gas. These valves can be automatically switched on and off, and the vacuum system is reliably protected from reflux to the vacuum chamber.