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:
Dec. 22, 1987
Filed:
Feb. 13, 1985
Applicant:
Inventors:
Katsumi Matsubara, Ibaraki, JP;
Riichi Uchida, Ibaraki, JP;
Masatoshi Muramatsu, Ibaraki, JP;
Kotaro Naya, Ebina, JP;
Tsuneharu Takagi, Yokohama, JP;
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
F04C / ;
U.S. Cl.
CPC ...
418201 ;
Abstract
A screw vacuum pump including a plurality of casings and a pair of rotors defining a plurality of working chambers. The working chambers are constituted by working chambers whose volumes undergo a change as the rotors rotate, and working chambers whose volumes undergo substantially no change as the rotors rotate. The screw vacuum pump is capable of achieving pressure of 10.sup.-1 to 10.sup.-4 Torr or a low or medium vacuum by means of a single pump operating in a single stage.