Scroll Dry Vacuum Pump of Working Principle and Structure
The scroll dry vacuum pump has simple structure and few parts; small clearance, small leakage rate, high compression ratio and stable pumping speed in a wide pressure range; because the volume of the compression chamber changes continuously, the driving moment changes little, the power changes little; the vibration noise is small, and the reliability is high.
Because of the above advantages of scroll pump, scroll pump has gradually replaced oil seal mechanical pump in some developed countries. At present, scroll pumps are mainly used in analytical instruments, semiconductor chip production lines, liquid crystal display production lines and scientific research equipment.
Because of the difficulty of manufacturing scroll pumps and the characteristics of their own profiles, the maximum pumping speed of scroll pumps is not more than 10L.S-1, and the minimum pumping speed is about 1L.S-1. All scroll pumps with pumping speed greater than 4L.S-1 adopt bilateral scroll structure, while pumps with pumping speed less than 4L.S-1 mostly adopt single-side scroll structure. In practical application, the largest consumption is 8L. S – 1 scroll pump with pumping speed.
After assembling the dynamic scroll and the static scroll with the same parameters of the scroll profile, the phase angle difference pi, the center distance r of the base circle (the value of R is related to the pitch of the involute and the thickness of the wall), several pairs of closed crescent cavities can be formed. When the eccentric axis drives the center of the moving scroll (i.e. the center of the base circle) to move around the center of the stationary scroll (i.e. the center of the base circle) in a circular orbit with radius r, the volume of these closed crescent cavities correspondingly enlarges or decreases, thus realizing the purpose of gas suction, compression and exhaust. The low-pressure gas enters the suction chamber from the suction port opened on the static scroll and is discharged from the exhaust port at the center of the static scroll after compression.
The gas of the scroll pump is compressed in the crescent cavity composed of the scroll rotor and the scroll stator. The scroll stator is fixed on the periphery of the frame. The suction port is arranged around the scroll stator, and the exhaust port is arranged at the center of the scroll body of the rotor and the stator. With the crankshaft turning, the scroll rotator rotates around the stator center with eccentricity r as its radius. The scroll rotator is also constrained by the anti-rotation mechanism. It can not rotate. It always keeps a fixed attitude. The center of the scroll rotator moves around the center of the scroll stator in a circle with radius R.
Dry scroll pump product characteristics:
No oil pump, no pollution to vacuum system
Sealing Design Using Independent Motor and Bearing
Small size: 351x181x140 mm
Compared with the old diaphragm dry pump (diaphragm pump), it has lower limit pressure.
No mechanical components that may cause disastrous system failures
Low noise, low vibration