MOLECULAR VACUUM PUMP Russian patent published in 2001 - IPC

FIELD: technological plants for pumping and maintaining vacuum at residual pressure of 10^-1 to 10^-2 Pa. SUBSTANCE: pump housing has holes for communication with atmosphere and with cavity to be evacuated. Rotor is mounted in housing at radial and axial clearances. Outer surface of rotor is provided with helical grooves over entire length; these grooves form flow section with at least two evacuation stages located between these holes. Grooves are made in form of multistart thread. Minor diameter of thread increases on suction side from holes communicated with cavity being evacuated towards discharge end to holes communicated with atmosphere. Shaft is located in axial hole; ends of this shaft are rigidly connected with housing. Radial clearance between shaft and hole is used as gas-dynamic support for rotor. EFFECT: reduced mass and overall dimensions of pump with no change in pumping speed and degree of gas compression. 9 cl, 2 dwg