The Roots vacuum pump is a kind of dual rotor positive displacement vacuum pump. There are two symmetrical rotors in the pump cavity. The rotor shape are two leaves shape, three leaves shape or four leaves shape.
The two rotors are mounted on a pair of parallel shafts in a certain phase and driven by a shaft end gear (i=1) to perform synchronous reverse rotation. The rotors are not in contact with each other and no contact with pump chamber wall, and there is usually a clearance of 0.15 to 1.0 mm between the rotors and chamber wall. The pump chamber is sealed (relatively sealed) by this clearance and high rotation speed.
Because there is no friction in the pump chamber, the rotor can run at high speed, generally 500 ~ 3000r/min. The lubrication position of the pump is limited to bearings, gears, and dynamic seals (the gearbox contains oil, and there is a pressure difference between the pump chamber and the pre-suction tube).
STRUCTURE DIAGRAM OF ROOTS VACUUM PUMP
1. Front End Cap 2. Oil Pointer
3. Pressure Sensor 4. Oil Filler Plug
5. Oil Drain Plug 6. Gear Side Bearing End Cap
7. Pump Body 8. Inlet Flange
9. Outlet Flange 10. Rotor
11. Motor Side Bearing Cap 12. Intermediate Flange
13. Oil Filler Plug At Oil Seal 14. Oil Drain Plug At Oil Seal
15. Cage Stents 16. Motor
17. Pump Foundation
Classification of Roots Vacuum Pump Structure Type
How the rotor is installed in the pump body determines the overall structure of the pump. At present, there are roughly two types of roots pumps at home and abroad:
1. Vertical Roots Pump
The inlet and outlet of vertical roots pump are in a horizontal position, which makes assembly and connection more convenient. However, the center of gravity of the pump is high, and its stability is poor at high speed, so this structure is mostly used for small pumps.
2. Horizontal Roots Pump
The inlet of the pump is higher than the exhaust port. Sometimes the exhaust ports are horizontally connected so that the intake and exhaust directions are perpendicular to each other. The exhaust port can be taken out in two directions, one to the exhaust pipe, and the other is blocked or connected to the bypass valve. The center of gravity of this structure is low to ensure the good stability at high speeds. This structure is generally used for large and medium-sized pumps.
