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. 13, 1992
Filed:
Aug. 30, 1990
Applicant:
Inventors:
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
F04D / ;
U.S. Cl.
CPC ...
415 24 ; 415115 ; 415914 ; 417 90 ;
Abstract
A vertical shaft pump to be disposed in a pump pit comprises a pump casing having a suction opening, and an impeller disposed in the pump casing below a position corresponding to the lowest water level in the pump pit below which the pump starts to suck air through the suction opening during operation. A series of intake ports are provided in the pump casing below the impeller with equal intervals in the circumferential direction of the pump casing. These intake ports act to introduce atmospheric air into the pump casing through intake pipes when the pressure at the intake ports is lowered below the atmospheric pressure.