Screw-type vacuum pump has sleeve located between shafts and associated rotors and with sum of wall thicknesses larger than depth of screw threads, the two sleeves having same wall thickness

摘要

The screw-type vacuum pump has two shafts(5,6) each carrying a rotor(1,2) with one or more outer screw threads(3,4). A sleeve(9,10) is located between the shafts and associated rotors and the sum of the wall thicknesses of the sleeves is somewhat larger than the depth of the screw threads. The two sleeves have the same wall thickness. The rotors are over-mounted, and the sleeves may be constructed in two sections. The sleeve may be fitted between one of the two shafts and associated rotor.