Patent ID: 6901752

Claim:
An exhaust processor having a tuning frequency for abatement of acoustic waves at the tuning frequency, the exhaust processor comprising: a housing defining an aperture, an exhaust tube extending through the aperture into the housing and defining an exhaust tube opening positioned inside the housing for communication of acoustic waves between the housing and the exhaust tube, a rotatable cover external to the exhaust tube for at least partially covering the exhaust tube opening, and a rotator arranged for rotating the cover about a longitudinal axis of the exhaust tube at least partially around the exhaust tube over the exhaust tube opening so as to change the extent to which the cover covers the exhaust tube opening to thereby adjust the tuning frequency of the exhaust processor, wherein the cover comprises a sleeve that surrounds the exhaust tube in coaxial relation therewith and defines a sleeve opening to uncover at least a portion of the exhaust tube opening upon rotation of the sleeve, the exhaust tube opening comprises a plurality of perforations, and the sleeve opening uncovers a first number of the perforations to establish the tuning frequency of the exhaust processor at a first tuning frequency upon rotation of the sleeve to a first position and uncovers a second number of the perforations to establish the tuning frequency of the exhaust processor at a second tuning frequency upon rotation of the sleeve to a second position.