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. 28, 1991
Filed:
Mar. 30, 1989
Applicant:
Inventor:
Noboru Tsuboi, Kakogawa, JP;
Assignee:
Kabushiki Kaisha Kobe Seiko Sho, Kobe, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
F04B / ; F04C / ;
U.S. Cl.
CPC ...
417295 ; 4182012 ;
Abstract
A screw type vacuum pump has in a passage leading to its suction port a check valve which is adapted to open the valve securely by hydraulic pressure to open the gas flow passage without the hunting phenomenon. This permits the selection of a spring with a suitable spring constant for seating the valve body on the valve seat securely and promptly to prevent reverse gas flows.