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. 17, 2000
Filed:
Nov. 07, 1997
Shinki Ohtsu, Naka-gun, JP;
Mitsuyuki Ishikawa, Hitachinaka, JP;
Masanori Yoshioka, Hitachinaka, JP;
Hitachi Koki Co., Ltd., , JP;
Abstract
A ball balancer for minimizing a dynamic unbalance of a moving part of a rotating machine such as a centrifuge is provided. The ball balancer includes a rotary balancer casing having disposed therein balls. The rotary balancer casing is mounted on the moving part coaxially with an axis of rotation thereof and has formed therein an inner side wall which is so curved that the balls are lifted away from the bottom of the balancer casing along the inner side wall by the centrifugal force and biased toward the opposite side of an unbalanced mass of the moving part when the rotational speed of the moving part exceeds a resonant speed that is a rotational speed of the moving part when matched with a natural frequency of the moving part, thereby counterbalancing the unbalanced mass of the moving part. In an alternative form, the balls include a first group having a large diameter and a second group having a small diameter. The large-diameter balls and the small-diameter balls are arranged alternately. Each of the large-diameter balls is lifted on adjacent one of the small-diameter balls by the reaction force produced by a shift in center between one of the large-diameter balls and adjacent one of the small-diameter balls arranged on the bottom of the balancer casing and biased toward the opposite side of the unbalanced mass of the moving part when the rotational speed of the moving part exceeds the resonant speed.