Muffler
AssigneeNoise Cancellation Technologies, Inc.
InventorsOwen Jones, Michael C. J. Trinder
Life of this patent
Estimating the term…
Abstract
A muffler for muffling noise in a fluid flow, such as exhaust gases from an internal combustion engine comprises a chamber, loudspeakers for injecting anti-noise into the chamber under the control of processing circuitry in dependence upon residual noise detected by a microphone. The gas flows from an inflow pipe to an outflow pipe past a radial aperture that produces an acoustic coupling between the chamber and the gas flow, to allow the anti-noise to mix with noise in the gas flow and produce noise cancellation. The coupling is so arranged that the chamber becomes pressurized by the gas flow, in use, so as to restrict hot gas flow through the chamber and thereby provide an essentially benign environment for the loudspeaker.
Claims18
A muffler for attenuating noise in a gaseous flow, said muffler comprising:
- a chamber means having a first end, and a second end with a receiving means, said first end having a first opening and said receiving means having a second opening;
- a conduit means for conveying gaseous stream into said chamber, said conduit means having a front end and a rear end and surrounded by said chamber, said conduit means terminating short of said second opening, thereby defining a radial aperture;
- and
- actuator means with a plurality of terminals, said actuator means positioned within said chamber for injecting anti-noise waves into said chamber so as to attenuate noise accompanying said gaseous flow, said actuator means being directed towards said conduit means, and wherein said terminals of said actuator means are terminated in a suitable electrical impedance;
- an acoustic coupling means including said radial aperture between said rear end of said conduit means and said chamber for acoustically coupling said chamber to the gaseous stream, and wherein the coupling means is configured so that the chamber becomes pressurized while in use so as to restrict flow of gas from said gasesous stream through said chamber.
Dependencies are inferred from the claim text.