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:
Sep. 20, 2011
Filed:
Jul. 10, 2006
Peter Zhao, Baltimore, MD (US);
Hung T. Du, Reisterstown, MD (US);
Garrett P. Mccormick, Manchester, MD (US);
Peter Zhao, Baltimore, MD (US);
Hung T. Du, Reisterstown, MD (US);
Garrett P. McCormick, Manchester, MD (US);
Black & Decker Inc., Newark, DE (US);
Abstract
A power tool has an electric motor with field windings. Each field winding includes two coils. When the motor is first energized, the two coils of each field winding are connected in series, reducing in-rush current. Upon expiration of a soft start period, the two coils of each field winding are connected in parallel. In another aspect, the field windings that are connected in series with a separate start winding when the motor is first energized. Upon expiration of the soft start period, the start winding is bypassed. In another aspect, the field windings are connected in series with a start impedance when the motor is first energized and a time delay relay having a set of delay contacts coupled across the start impedance energized. Upon expiration of the soft start period, the time delay contacts close, bypassing the start impedance. In an aspect, the motor is a universal motor.