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:
Oct. 10, 2000
Filed:
Jun. 16, 1999
Nigel Paul Schofield, Horsham, GB;
Michael Henry North, Reigate, GB;
The BOC Group plc, Windlesham, GB;
Abstract
A compound vacuum pump incorporating a screw mechanism section. The screw mechanism section comprising two externally threaded rotors mounted on respective shafts in a pump body. The rotors are adapted for counter-rotation in a first chamber within the pump body with intermeshing of the rotor threads to pump gas by action of the rotors. The root diameter of each rotor increases and the thread diameter of each rotor decreases in a direction taken from pump inlet and in which the gas is pumped. The pump additionally incorporates a roots mechanism section comprising two roots-type profile rotors also mounted on the respective shafts and adapted for counter-rotation in a second chamber within the pump body situated at an inlet end of the pump.