MULTI-FREQUENCY QUARTER-WAVE RESONATOR FOR AN INTERNAL COMBUSTION ENGINE

摘要

A variable noise attenuation element is disclosed that comprises a tube, at least one valve seat, at least one valve body and a wire connected to the valve body. The tube has an overall length that defines a first effective length for noise attenuation. The valve seat is disposed in the tube. Retraction of the wire brings the valve body into engagement with the valve seat to selectively define a second effective length of the tube that is less than the overall length.