US006138947A [ii] Patent Number: 6,138,947  Date of Patent: *Oct. 31,2000
 ACTIVE NOISE CONTROL SYSTEM FOR A DEFINED VOLUME
 Inventors: William A. Welsh, North Haven;
Charles A. Yoerkie, Jr., Newington,
both of Conn.
 Assignee: Sikorsky Aircraft Corporation,
[ * ] Notice: This patent issued on a continued prosecution application filed under 37 CFR 1.53(d), and is subject to the twenty year patent term provisions of 35 U.S.C. 154(a)(2).
 Appl. No.: 08/997,435  Filed: Dec. 23, 1997
Related U.S. Application Data
 Provisional application No. 60/056,710, Aug. 22, 1997.
 Int. CI. B64C 27/00
 U.S. CI 244/17.27; 244/1 N
 Field of Search 244/1 N, 17.11,
244/17.13, 17.27, 54
 References Cited
U.S. PATENT DOCUMENTS
FOREIGN PATENT DOCUMENTS
2 217 951A 11/1989 United Kingdom G01K 11/16
Primary Examiner—Peter M. Poon
Assistant Examiner—-Tien Dinh
Attorney, Agent, or Firm—Adam C. Solomon
An active noise control system for minimizing undesirable acoustic noise in a defined volume, wherein the undesirable acoustic noise is generated by high frequency structural vibrations emanating from a vibration source structurally coupled to the defined volume at a structural interface. The active noise control system comprises a sensor subsystem disposed in combination with the defined volume for sensing the undesirable acoustic noise in the defined volume, an actuator subsystem disposed proximal to the structural interface, and a controller functionally interconnecting the sensor subsystem to the actuator subsystem, the controller being operative to receive input from the sensor subsystem and to transmit command signals to the actuator subsystem in response thereto for generating selected high frequency counter-vibrations that are interactive with the high frequency structural vibrations to minimize the undesirable acoustic noise in the defined volume.
19 Claims, 6 Drawing Sheets