Two-stage rotary vane vacuum pumps and their operating mode
A rotary vane vacuum pump consists of a cylindrical interior space where an eccentrically located rotor moves. In the rotor there are several slits in which the vanes are placed.
Because of the centrifugal strength the vanes are pressed radial against the case and divide thus the interior space into several chambers. As a result of rotation a growing sickle-shaped suction chamber appears which is filled by the gas to be sucked off. This sickle-shaped suction chamber go on rotating till the maximum volume is reached, then one vane closes the suction chamber to the inlet opening.
After reaching the maximum volume, because of rotation and geometry of the inside chamber and of the rotor, the suction chamber is narrowed and the gas is compressed. The height of compression is determined by the constructive geometry and the manufacturing tolerances only.
After the gas compression the outlet opening is released by a vane and the compressed gas can escape. This output occurs so long till the minimum volume of chamber is reached.
It is possible within one rotation to reach several working cycles, because depending on the number of vanes several chambers can be defined.