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. 03, 1992
Filed:
Apr. 27, 1989
Applicant:
Inventor:
Akira Yamamura, Tokyo, JP;
Assignee:
Nippon Ferrofluidics Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
F04B / ;
U.S. Cl.
CPC ...
417201 ; 4174234 ;
Abstract
A composite vacuum pump system having first and second vacuum pumps each having its own rotor and drive motor in which the exhaust of the first vacuum pump is removably coupled to the inlet of the second vacuum pump and the first vacuum pump rotor is driven at a constant torque and in which the second vacuum pump has an inlet for permitting the introduction into the pump of a heavy gas for increasing the efficiency of the pumping system.