ALEXANDRIA, Va., June 9 -- United States Patent no. 12,286,974, issued on April 29, was assigned to Edwards Ltd. (Burgess Hill, Great Britain).
"Multi-stage turbomolecular pump" was invented by Nigel Paul Schofield (Burgess Hill, Great Britain) and Stephen Dowdeswell (Burgess Hill, Great Britain).
According to the abstract* released by the U.S. Patent & Trademark Office: "A vacuum pump comprising a turbomolecular stage and a drag stage, the vacuum pump comprising a stator and a rotor. The rotor comprises a turbomolecular rotor and a drag rotor attached together. The turbomolecular rotor comprises a hub from which a plurality of blades extend, the hub comprising a mounting portion for mounting to a spindle of a motor and a hollow cylindric...