Patent ID: 8105013
Filing Date: 2012-01-31
Classification: F04D

Abstract:
1. A vacuum pump comprising a first pumping section, a second pumping section downstream from the first pumping section, a third pumping section downstream from the second pumping section, a first pump inlet through which fluid can enter the pump and pass through each of the pumping sections towards a pump outlet, and a second pump inlet through which fluid can enter the pump and pass through only the second and the third pumping sections towards the outlet, wherein the third pumping section comprises a helical groove formed in a stator thereof, and at least one of the first and second pumping sections comprises at least one turbo-molecular stage and, downstream therefrom, a rotor comprising a helical groove, wherein the depth of the groove at the inlet side of the rotor is greater than the depth of the groove at the inlet side of the stator.