Structure of screw vacuum pump
The drive shaft connects the active rotor and drives the driven rotor to rotate by synchronous gear. A cooling water passage is opened on the shell to cool the temperature of the rotor and the exhaust port. The synchronous gear and bearing are lubricated by oil. The inside of the bearing and the shell is sealed by sealing parts to achieve oil-free effect. The structure of dry screw vacuum pump is similar to that of oil-free screw compressor in sealing and lubrication. In general, mechanical seals are used at the exhaust end of vacuum pump and double lip seals are used at the intake side. In terms of transmission mode, the current general purpose is direct-connected motor, which is connected with the rotor by coupling, and very few are driven by belt or transmission chain. Because of no internal compression process, the exhaust temperature of the equal pitch screw pump is very high. If the cooling effect is not good, it will cause the deformation of the rotor and the casing, which will affect the exhaust effect. Cooling shell is an indispensable link. Water cooling is the most common method. Cooling water is passed through the shell body and the outside of the bearing to achieve the purpose of cooling the shell and then cooling the rotor.
Overview of Production at Home and Abroad
1. The domestic enterprises of screw vacuum pumps have been studying the profile and structure performance since 2004. In 2007, when the domestic dry screw vacuum pump market was basically occupied by foreign manufacturers, domestic companies invested a lot of money to transfer the product into batch production, and received strong support from the state to win various provincial and national science and technology awards and funds. SP dry screw vacuum pump has the advantages of higher limit vacuum, lower power consumption, energy saving and maintenance-free. It is an updated product of oil seal/jet/water ring vacuum pump, which has been widely used in major pharmaceutical and chemical enterprises in China. According to different technological conditions, the over-current components (i.e. the parts of rotor and pump body that contact with gas) have anti-corrosion coatings, including nickel-phosphorus coatings and PTFE coatings.
2. The screw oil-free compressed vacuum pump officially launched by Germany and Japan at the end of 1999 is a dry pump specially designed for industrial applications (non-semiconductor applications). It is a brand-new design and is specially designed to solve the difficult vacuum problems in industrial applications, such as dust, tar and so on. This pump also uses a variable pitch rotor, with internal compression process, no bearing and seal in the pump chamber, which greatly reduces the failure rate. There is no internal valve in the pump chamber, so it has strong dust and tar resistance. The screw of this pump adopts internal hollow cooling, which can reduce the temperature and thermal deformation of the rotor and prolong the life of the screw.
