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US 4,333,545 AGranted
Back-fire resistant lock seam for muffler shells
AssigneeThrush Incorporated
InventorPeter Roberts
Life of this patent
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Abstract
A muffler wherein the shell comprises a metal sheet the ends of which are retained together in an interlocked joint has a shielding strip on the interior of the tube secured thereto in overlapping relation to the interlock. Preferably the sheet is a two ply, one end of the inner ply being retained in the joint, the other end forming the shielding strip, the edge of which is spot welded to the interior surface of the shell. The muffler is resistant to damage from back-fires.
Claims11
A muffler shell comprising:
- a two ply sheet of metal formed into a tube,
- an interlock joining the ends of the sheet to retain it in tubular formation, said interlock comprising complementary hook elements located at said ends, a hook element at one said end including both plies therein, the hook element at the other said end including the outer ply only, the inner ply at the other said end extending beyond the hook element to overlap said interlock thereby forming a shield therefor.
Method for the construction of a muffler shell comprising:
- providing first and second plies of a generally rectangular metal sheet;
- rolling said metal sheet whereby opposed ends thereof are in generally mutually confronting relationship;
- folding the metal sheet along one of the confronting ends to form a hook element including both said plies;
- folding the outer ply only of the other confronting end to form a complementary hook element;
- joining said hook elements and forming a seam, and
- spot welding the inner ply of the other confronting end along the edge thereof to the interior surface of said muffler so as to form a protective shield for said seam.
3 more elements
Dependencies are inferred from the claim text.