Folded shell muffler

Claim 2

In the method of making an elongated oval shaped silencing muffler having a length and a major width and a minor width, said muffler including an outer tubular oval shell and at least one pair of parallel internal longitudinally extending flat walls of less length than said shell and extending across the minor width of the shell, the steps comprising first, forming a flat blank having a first section with a length substantially equal to the length of the shell and a second section joined to the first and having a length substantially equal to the length of the walls, and second folding said blank into oval form with said first section on the outside to form at least part of said shell and said second section in the shape of a rectangular internal tube on the inside of the shell, and securing the rectangular tube on opposite minor width sides to the outer shell.

Claim 3

A method as set forth in claim 1 wherein said first step includes forming a third section in said blank which is attached to said second section and which is substantially the same length as the first section and the combined widths of the first and third sections is at least equal to the perimeter of the shell and said second step includes the substeps of forming a part of a shell with said first section and folding said second section to form said internal tube with the first section and then folding the third section onto said shell around the internal tube.

Claim 4

A method as set forth in claim 2 wherein said first step includes forming said second section so that it has a width substantially equal to the height of two of said walls plus the distance between said walls and forming louvers in at least one of said wall portions.

Claim 5

A method as set forth in claim 3 wherein said first step includes forming extensions on said second section in alignment with the two wall portions and said second step includes bending said extensions at angles to the wall so that said extensions form transverse partitions extending from the wall to the shell.

Claim 6

In a muffler for silencing gases having an oval shaped outer shell and inner gas passages, a one-piece monolithic sheet member having first and second parallel longitudinally extending coextensive end edges, said sheet member including a pair of parallel external wall sections defining the top and bottom of the outer shell and curved side sections joining the wall sections, said sheet further including a pair of parallel internal flat wall sections forming longitudinal partitions extending transversely to the first wall sections and across the minor width of the oval shell and a flat connecting wall section joining the internal wall sections and extending at substantially right angles thereto and parallel to the exterior wall sections, said internal wall sections being engaged opposite sides with opposite sides of the shell across the minor width of the shell and furnishing transverse support for said oval shell, said internal wall sections being shorter than the external wall sections and defining said inner gas passages.

Claim 7

In a muffler for silencing gases having an oval shaped outer shell and inner gas passages, a one-piece monolithic sheet member having first and second parallel longitudinally extending coextensive end edges, said sheet member including a pair of parallel external wall sections defining the top and bottom of the outer shell and curved side sections joining the wall sections, said sheet further including a pair of parallel internal flat wall sections forming longitudinal partitions extending transversely to the first wall sections and across the minor width of the oval shell and a flat connecting wall section joining the internal wall sections and extending at substantially right angles thereto and parallel to the exterior wall sections, said internal wall sections being engaged opposite sides with opposite sides of the shell across the minor width of the shell and furnishing transverse support for said oval shell, said internal wall sections being shorter than the external wall sections and defining said inner gas passages.

Claim 8

A muffler as set forth in claim 5 wherein each of said flat internal wall sections includes as a part of said sheet an extension extending at right angles to the wall section and forming a transverse partition in said shell, said shell having end headers closing opposite ends, and inlet and outlet gas flow bushings supported in said headers and extensions.