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:
May. 26, 1992
Filed:
Jul. 10, 1990
Gilles Baret, Annecy, FR;
Denis Perrillat-Amede, Annecy le Vieux, FR;
Alcatel CIT, Paris, FR;
Abstract
A mechanical pump assembly (20) for pumping a secondary vacuum, the assembly comprising two pumping stages, the first stage having a suction inlet (9) and the second stage having a suction orifice (10), said inlet and said orifice both opening out to the outside, both stages having a common delivery outlet (4), the pump assembly being characterized in that both of said pumping stages are of the Holweck drum type, said first stage having a compression ratio of about 50 for a gas such as helium and of about 30,000 for air, the pumping speed of the first stage being about 4 l/s for air and about 2.5 l/s for said gas, and in that said second stage has a pumping speed of about 3.5 l/s for air and of about 2 l/s for said gas, the nominal speed of rotation of said mechanical pump assembly being about 27,000 rpm.