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:
Mar. 24, 1992
Filed:
Nov. 07, 1989
Eldon W Ziegler, Columbia, MD (US);
John W Gardner, Silver Springs, MD (US);
Noise Cancellation Technologies, Inc., Columbia, MD (US);
Abstract
An active sound attenation system for combustion engine exhaust systems and the like is disclosed. To protect the counter-noise acoustic wave generator from the environment of the medium propagating the undesirable noise, an acoustically tuned anti-noise chamber is interposed between the wave generators 19, 19A and the location of the medium with the undesirable noise. To provide for global cancellation at the outlet end 4, of the exhaust pipe 10, the anti-noise chamber 11, 11A has an annular opening disposed substantially in the plane 4 of the exhaust pipe outlet thereby giving the undesirable noise and the cancelling noise an apparent common source.