Patent ID: 9670931
Date: 2017-06-06
CPC Classifications: F04D

Claim:
1. A rotary vacuum pump comprising: a pump housing in which an inlet port and an outlet port are defined; a plurality of pumping stages arranged inside the pump housing between the inlet port and the outlet port for pumping a gas from the inlet port to the outlet port, each of the pumping stages comprising a stator stage integral with the pump housing and a cooperating rotor disc integral with a rotating shaft centrally arranged in the housing, wherein the plurality of pumping stages comprises: a first set of pumping stages having rotor discs with a first outer diameter followed in the flow direction of the pumped gas by a second set of pumping stages having rotor discs with a second outer diameter different from the first outer diameter; and an intermediate pumping stage interposed between the first set of pumping stages and the second set of pumping stages, the intermediate pumping stage comprising: