Silencer for attenuating a sound or noise transmitted through an air passage of a duct
US6078671A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 4, 1997 |
| Grant date | Jun 20, 2000 |
| Priority date | — |
| Expiry date | Sep 4, 2017 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02M35/1283
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
A silencer is adapted to be mounted on an air duct. The silencer includes a noise detecting microphone for detecting a noise transmitted through the air passage of the duct, a loud speaker for delivering on the basis of the noise detected by the microphone into the air passage a sound which is substantially the same as the noise except that the phase of the sound is the reverse of that of the noise to thereby enable the sound to be superimposed on the noise and attenuate the noise, and vibration shield provided between the microphone and the wall of said duct for shielding any vibrations transmitted through the wall to the microphone. The vibration shield includes a duct element made from a sound absorbing material which element forms a part of the duct and the noise detecting microphone is mounted to the duct element. Alternatively, the vibration shield can include a vibration shield member mounted on the outside of the duct where an opening is provided in the wall of the duct and a noise detecting microphone is provided with a windscreen around a sound collecting portion of the microphone. The windscreen is inserted into a through hole provided in the shield member to fasten the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.