Ex-Broad Band Resonators (05-Nov-2009)

Modular broad band resonator

Description of the invention

A broadband resonator generally attenuates transmitted sound or noise depending upon the configuration of a given number of cavities and within a limited range of frequencies for which the cavities are configured. Broadband resonators are typically custom designed for each application, making them application specific, and difficult (read expensive) to modify or redesign. In the prior art, such resonators are not configured and adapted to be quickly and inexpensively reconfigured to meet changing design needs, such as to meet changing design requirements regarding sound attenuation levels as a function of sound frequency.

In order to provide a broadband resonator that may be configured for an expanded frequency range, it is necessary to provide more multiple opening cavities. In the prior art where resonators are custom designed for specific applications, any design later changes impact custom tooling (such as injection molds, automated manufacturing, assembly and testing equipment).

Additionally, when it is desired to provide additional attenuation at higher frequencies, then one alternative is to provide one or more expansion chambers. These expansion chambers may eliminate the need for one or more multiple opening chambers or cavities. The sound attenuation level at higher frequencies may be changed according to the expansion ratio of the expansion chamber. It is also possible to change the shape of the expansion chamber to fit the available installation space and packaging and so as to provide more attenuation.

The disclosed invention relates to a modular broadband resonator having multiple cavities and multiple openings to attenuate sound over a broad range of frequency. The broadband resonator may advantageously be assembled from modular components, which may be provided in varying standardized configurations. The components are advantageously selected and arranged to have a specific desired attenuation characteristics over one or more frequency bands. The broadband modular resonator may also include one or more expansion chamber modules configured to attenuate higher frequency noise at constant amplitude. Expansion chamber may be arranged within the grouping of multiple cavity rings or at the end of an array of rings.

An exemplary broadband resonator consistent with the present invention is shown at the left, having an expansion chamber together with a plurality of cavities arranged along and over the outer portion of an air duct. The resonator may be configured and assembled from a plurality of closed volume modules each designed and configured to have one or more cavities. The modules may have ring shapes as illustrated and each ring may preferably have a "U" shaped cross section.

                              The ring shaped modules may be configured to assemble in a side-by...