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:
Feb. 14, 1995
Filed:
Mar. 09, 1994
Frederic G Pla, Schenectady, NY (US);
Robert A Hedeen, Clifton Park, NY (US);
General Electric Company, Schenectady, NY (US);
Abstract
A fan assembly has a fan motor and first and second generally identical and spaced apart fans each rotationally attached to the fan motor to turn at the same rotational speed. Each fan has an equal number of generally identical fan blades and produces noise including a tone having a frequency equal to its rotational speed times its number of fan blades. The fan blades of one fan are angularly offset at a relative phase angle with respect to the fan blades of the second fan such that the tones of each fan generally cancel each other out. An equation is provided for a ducted fan assembly relating the relative phase angle to the rotational speed of the fans, the number of fan blades of each fan, the geometry of the duct, and the speed of sound in air within the duct.