Embossed shell for spun mufflers
View Patent ↗An exhaust muffler with a single-wall shell having a first end and a second end features a plurality of embossments formed on the shell and extending from the first end of the muffler to the second end of the muffler. The embossments are arranged in a pattern such that any straight line extending from the first end to the second end intersects at least one of the embossments, thereby imparting increased stiffness to the muffler shell. Each of the embossments preferably have an elliptical shape and are arranged in rows extending substantially parallel to a longitudinal axis of the muffler. The embossments in any given row are rotated ninety degrees from the embossments in preceding and succeeding rows and are spaced to provide an interlocking pattern.
1. An exhaust muffler comprising:
a muffler shell including a first end and a second end; and
a plurality of elliptically shaped embossments formed on said muffler shell extending from said first end to said second end and arranged in rows extending substantially parallel to a longitudinal axis of the exhaust muffler, said embossments in any given row rotated on the order of ninety degrees to said embossments in preceding and succeeding rows, said plurality of embossments arranged in a pattern such that a line extending from said first end to said second end intersects at least one of said embossments, thereby increasing the stiffness of said muffler shell.
2. The exhaust muffler of claim 1 , wherein said embossments have a height from a surface of said muffler shell of approximately less than twice the thickness of said muffler shell.
3. A method for designing an exhaust muffler having a natural resonant frequency higher than the resonant frequency of an engine, the method comprising the steps of:
(a.) providing a single-shell muffler;
(b.) stamping a plurality of embossments onto said single-shell muffler in a first pattern, said embossments having a first depth;
(c.) analyzing said single-shell muffler to determine a natural resonant frequency of the single-shell muffler;
(d.) comparing said natural resonant frequency of said single-shell muffler to the resonant frequency of the engine, and if said natural frequency of said single-shell muffler is approximately less than or equal to said resonant frequency of the engine, stamping a second plurality of embossments onto a second single-shell muffler, said embossments having a second pattern or a second depth, and repeating steps (c.) and (d.) until the natural resonant frequency of said muffler exceeds the resonant frequency of the engine.
4. An exhaust muffler comprising:
a muffler shell; and
a plurality of embossments, each having a major axis and a minor axis smaller than the major axis, formed on the muffler shell and arranged in rows extending substantially parallel to a longitudinal axis of the exhaust muffler, the embossments in any given row having major axes rotated from major axes of embossments in preceding and succeeding rows.
5. The exhaust muffler of claim 4 wherein the embossments in any given row have major axes rotated on the order of ninety degrees from major axes of embossments in preceding and succeeding rows.
6. The exhaust muffler of claim 4 wherein the embossments are elliptical.