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, 1989
Filed:
Dec. 01, 1987
Applicant:
Inventor:
Friedrich R Hertrich, Boulder, CO (US);
Assignee:
Digital Equipment Corporation, Maynard, MA (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H02K / ;
U.S. Cl.
CPC ...
310186 ; 310156 ; 310179 ; 310187 ; 310254 ; 318254 ;
Abstract
A brushless DC motor having a number of armature poles which is neither a multiple nor a submultiple of the number of field poles, thereby providing a relatively high cogging-ripple frequency. The field pole faces, which are generally arcuate in cross-section, have centrally disposed depressions. These depressions reduce the torque exerted by the armature when pole boundaries of the armature pass by the centers of the field poles. This reduces both torque ripple and cogging ripple and it doubles the frequency of torque ripple.