The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 13, 2001
Filed:
Jun. 16, 1999
Nigel Paul Schofield, Horsham, GB;
Michael Henry North, Reigate, GB;
The BOC Group plc, Windlesham, GB;
Abstract
A vacuum pump incorporating a screw mechanism section and comprising two externally threaded rotors mounted on respective shafts in a pump body. The externally threaded rotors are adapted for counter-rotation in a first chamber within the pump body with intermeshing of the rotor threads in order to pump gas from a pump inlet by action of the rotors. The root diameter of each rotor increases and the thread diameter of each rotor decreases in a direction from pump inlet and in which the gas is pumped. The two externally threaded rotors are positioned in the pump body by means of shaft bearings located inside cavities in the rotors. The cavities are sealed at the ends closest to the pump inlet.