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A system and method for dissipating at least one pressure wave in an exhaust gas flow is disclosed. A vehicular exhaust system directs the exhaust gas flow through a plurality of coaxial and perforated generally cylindrical tubes contained within an insulated canister towards a perforated partition

A system and method for dissipating at least one pressure wave in an exhaust gas flow is disclosed. A vehicular exhaust system directs the exhaust gas flow through a plurality of coaxial and perforated generally cylindrical tubes contained within an insulated canister towards a perforated partition plate. Through a series of apertures in the tubes and plate, the at least one pressure wave is dissipated such that sound attenuation is achieved without output loss from the engine.

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The invention claimed is: 1. A vehicular exhaust system for dissipating at least one pressure wave, the system comprising: a first generally cylindrical tube having a first end that receives the at least one pressure wave, a second end that directs the at least one pressure wave to an outlet tube,

The invention claimed is: 1. A vehicular exhaust system for dissipating at least one pressure wave, the system comprising: a first generally cylindrical tube having a first end that receives the at least one pressure wave, a second end that directs the at least one pressure wave to an outlet tube, a first length extending therebetween, and a first plurality of apertures contained therein; a second generally cylindrical tube extending a second length from a proximal end proximate to the first end to a distal end, the second generally cylindrical tube located radially outward of the first generally cylindrical tube and coaxial therewith, thereby forming a first generally annular passageway between the first generally cylindrical tube and the second generally cylindrical tube, the second generally cylindrical tube having a second plurality of apertures that are substantially the same size as the first plurality of apertures; the outlet tube coupled to the first generally cylindrical tube; a partition plate positioned within the first generally cylindrical tube at an axial distance along the first length, wherein the axial distance is slightly shorter than the second length and the partition plate is positioned proximate to the distal end of the second generally cylindrical tube, the partition plate having a third plurality of apertures, and the partition plate being located adjacent to a taper of a diameter of the first or the second generally cylindrical tube; and a canister having a generally cylindrical wall, an inlet opening, and an outlet opening, wherein the first end of the first generally cylindrical tube is fixed to the inlet opening and the outlet tube is fixed to the outlet opening of the canister, the canister containing an insulating material between the cylindrical wall and the second generally cylindrical tube; wherein the partition plate permits a portion of the at least one pressure wave to pass through the third plurality of apertures in the partition plate and directs the remaining portion of the at least one pressure wave to pass through the first plurality of apertures and into the first generally annular passageway. 2. The system of claim 1 wherein the first generally cylindrical tube further comprises a first diameter extending a first portion of the first length that tapers to a smaller second diameter extending a second portion of the first length and the second generally cylindrical tube further comprises a constant diameter, wherein an axial location of the taper from the first diameter to the smaller second diameter is located slightly upstream of the partition plate, the taper extending a third portion of the first length, the third portion located in a region proximate to the partition plate. 3. The system of claim 2 wherein the first generally annular passageway increases in volume proximate the second diameter of the first generally cylindrical tube, wherein the third portion of the first length that includes the taper to the second diameter is positioned proximate to the distal end of the second generally cylindrical tube. 4. The system of claim 2 wherein the partition plate is located axially within the first generally cylindrical tube proximate the second diameter. 5. The system of claim 1 wherein the first generally cylindrical tube further comprises a constant diameter and the second generally cylindrical tube further comprises a first diameter extending a first portion of the first length that tapers to a larger second diameter extending a second portion of the first length, wherein an axial location of the taper from the first diameter to the larger second diameter is located slightly upstream of the partition plate, the taper extending a third portion of the first length, the third portion located in a region proximate to the partition plate. 6. The system of claim 5 wherein the first generally annular passageway increases in volume proximate the second diameter of the second generally cylindrical tube. 7. The system of claim 5 wherein the partition plate is located axially within the first generally cylindrical tube proximate the second diameter. 8. The system of claim 1 wherein the second generally cylindrical tube further comprises a wire screen having a very fine mesh configured to diffuse energy associated with the at least one pressure wave located about an outer surface of the second generally cylindrical tube and axially proximate the partition plate. 9. The system of claim 1 wherein the partition plate has a surface area and a rounded edge, the plate oriented generally perpendicular to the first generally cylindrical tube such that the edge extends in an axial direction towards the first end of the first generally cylindrical tube. 10. The system of claim 1 wherein the third plurality of apertures in the partition plate cover approximately 45%-60% of the surface area. 11. A vehicular exhaust system comprising: an inner core assembly comprising: a first generally cylindrical tube having a first end, a second end, a first length extending therebetween, and a first plurality of apertures contained therein, the first generally cylindrical tube having a first diameter that tapers to a smaller second diameter; a second generally cylindrical tube located radially outward of the first generally cylindrical tube and coaxial therewith, thereby forming a first generally annular passageway between the first generally cylindrical tube and the second generally cylindrical tube, the second generally cylindrical tube having a second plurality of apertures and a constant diameter that extends a second length from proximate the first end; an outlet tube coupled to the first generally cylindrical tube; a partition plate positioned within the first generally cylindrical tube at an axial distance along the first length proximate the second diameter, the partition plate having a third plurality of apertures and a surface area, wherein the third plurality of apertures in the partition plate cover approximately 45%-60% of the surface area; and a canister having a generally cylindrical wall, an inlet opening, and an outlet opening, the canister encompassing the inner core assembly and containing an insulating material between the inner core assembly and the generally cylindrical wall; wherein the partition plate permits a portion of the at least one pressure wave to pass through the third plurality of apertures in the partition plate and directs the remaining portion of the at least one pressure wave to pass through the first plurality of apertures and into the first generally annular passageway. 12. The system of claim 11 wherein the second generally cylindrical tube further comprises a wire screen located about the second generally cylindrical tube and axially proximate the partition plate. 13. The system of claim 11 wherein the partition plate is located along the first length at an axial distance that is significantly greater from the first end of the first generally cylindrical tube than from the second end of the first generally cylindrical tube. 14. The system of claim 13 wherein the partition plate has a rounded edge, the plate is oriented generally perpendicular to the first generally cylindrical tube such that the edge extends in an axial direction towards the first end of the first generally cylindrical tube. 15. The system of claim 11 wherein the insulating material located within the canister absorbs part of the portion of the at least one pressure wave that exits from the first generally annular passageway through the second plurality of apertures. 16. A method of dissipating at least one pressure wave in a fluid passing through a vehicular exhaust system, the method comprising: providing a vehicular exhaust system comprising a generally cylindrical canister having coaxial first and second tubes located therein, wherein the first tube has a first plurality of apertures, the second tube has a second plurality of apertures, a passageway formed between the first and second passageway, and a partition plate having a third plurality of apertures is located in the first tube, wherein the first tube has a first end that receives the at least one pressure wave, a second end that directs the at least one pressure wave to an outlet tube, and a first length extending therebetween, and wherein the partition plate is located along the first length at an axial distance that is significantly greater from the first end of the first generally cylindrical tube than from the second end of the first generally cylindrical tube; directing the fluid flow through an inlet opening in the canister and into the first tube via the first end; permitting a first portion of the fluid to pass through the first plurality of apertures and into the first passageway whereupon some of the first portion passes through the second plurality of apertures and into the canister; permitting a second portion of the fluid to pass through the third plurality of openings in the partition plate; directing the remaining fluid through the first plurality of apertures and into the first passageway proximate the partition plate, wherein a volume of the first passageway is increased by a taper located slightly upstream of the partition plate, wherein the taper encompasses a portion of the first length that decreases a diameter of the first tube from a first diameter to a smaller second diameter, the portion of the first length located in a region proximate to the partition plate; and directing the fluid present in the first passageway either through the second plurality of apertures or back into the first tube and towards an outlet opening in the canister. 17. The method of claim 16 further comprising absorbing some of the pressure wave from the first portion that passes through the second plurality of apertures with the insulation. 18. The method of claim 16 wherein the fluid is exhaust gas from an internal combustion engine. 19. The method of claim 16 wherein the at least one wave contained in the fluid is dissipated into a plurality of smaller waves by at least the partition plate and the first, second, and third plurality of apertures.