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US 5,493,615 AGranted
Piezoelectric driven flow modulator
AssigneeNoise Cancellation Technologies, Inc.
InventorsMichael J. Burke, George W. Tye
Life of this patent
Estimating the term…
Abstract
An elliptically shaped flow modulator in a duct with a circular cross section is used to produce a time varying head loss in a steady fluid flow in the duct, which results in an unsteady volume velocity at the end of the duct which radiates an acoustic field; the flow modulator can be used in place of a conventional acoustic source in an active noise control system.
Claims4
An active anti-pulsatory system for controlling low frequency noise from a duct, said system comprising
- an elongated duct means circular in cross-section,
- a modulator valve means rigidly affixed at a predetermined angle inside said duct means so as to allow airflow thereby, said modulator means being elliptically shaped,
- actuator means affixed to said modulator valve means and adapted upon electrical stimulation to change the flow characteristics of said duct means by causing said valve means to deform.
Dependencies are inferred from the claim text.