MULTI-STAGE PUMP WITH TRANSVERSE WALL

摘要

The present invention relates to a multi-stage vacuum pump which has a plurality of pumping stages. The pump comprises a stator forming the pumping chambers of respective pumping stages and at least one shaft, for supporting a plurality of rotors for rotation in respective pumping chambers. The stator comprises: a stator envelope which extends over an axial extent of a plurality of stator stages thereby circumscribing said at least one shaft and forming an internal profile of a plurality of stator stages: and a plurality of transverse walls located on either axial side of the stator stages to form respective said pumping chambers. At least one of the transverse walls is an inter-stage between stator stages and the stator envelope is configured to circumscribe the inter-stage for location of said inter-stage radially inward of the stator part.