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:
Jul. 24, 1990
Filed:
Dec. 15, 1989
Applicant:
Inventors:
Assignee:
Ebara Corporation, Tokyo, JP;
Primary Examiner:
Int. Cl.
CPC ...
F04C / ; F04C / ;
U.S. Cl.
CPC ...
418-9 ; 418150 ; 418200 ;
Abstract
A two-shaft rotary machine for use in a vacuum pump system includes rotors having a specific profile whereby any vibration and noise generated by the machine is minimized and its efficiency is increased. The number of lobes of each rotor is three or more. The tip and root portions of each rotor are defined by circular arcs, respectively, which are made smoothly continuous with each other through an involute curve. The ratio of the diameter of the tip circle to the diameter of the root circle is selected to fall within a range which is given by a specific expression.