Plastic muffler with Helmholtz chamber

A muffler for a vehicle exhaust system comprising:

• a plastic outer shell defining an internal cavity, said plastic outer shell including an inlet and an outlet;
• a metal inner pipe positioned within said internal cavity and extending from said inlet to said outlet;
• a Helmholtz chamber formed within said plastic outer shell;
• a shielding cartridge comprising a metal outer pipe that surrounds at least a portion of an axial length of said metal inner pipe within said internal cavity, and including packing material positioned within a gap formed between said inner and said outer metal pipes;
• and
• a Helmholtz neck spaced radially from said metal outer pipe and supported by said plastic outer shell via a baffle extending in a direction transverse to a central axis extending along a length of said metal inner pipe, said Helmholtz neck and baffle cooperating to separate said internal cavity into first and second chambers, with one of said first and second chambers comprising said Helmholtz chamber and the other of said first and second chambers comprising an expansion chamber.

A muffler for a vehicle exhaust system comprising:

• a plastic outer shell defining a central axis and providing an internal cavity, said plastic outer shell including an inlet and an outlet extending along said central axis, and wherein said internal cavity is not fully packed such that at least a portion of said internal cavity is free from packing material;
• a metal inner pipe positioned within said internal cavity and extending along said central axis from said inlet to said outlet to direct exhaust gas through said plastic outer shell;
• a Helmholtz chamber formed within said plastic outer shell;
• a Helmholtz neck associated with at least one of said metal inner pipe or said plastic outer shell;
• a thermally insulating end plate decoupling said plastic outer shell from said metal inner pipe at each of said inlet and said outlet;
• and
• a shielding cartridge comprising a metal outer pipe that surrounds at least a portion of an axial length of said metal inner pipe within said internal cavity, wherein said thermally insulating end plate extends between said metal outer pipe and said plastic outer shell at least at one of said inlet and said outlet, and including packing material positioned within a gap formed between said inner and said outer metal pipes.

A muffler for a vehicle exhaust system comprising:

• a plastic outer shell defining a central axis and providing an internal cavity, said plastic outer shell including an inlet and an outlet extending along said central axis;
• a metal inner pipe positioned within said internal cavity and extending along said central axis from said inlet to said outlet;
• end faces at each of the inlet and outlet, and including a thermally insulating end plate decoupling said plastic outer shell from said metal inner pipe at each of said inlet and said outlet, and wherein the end faces are formed in part by the plastic outer shell and in part by the thermally insulating end plates;
• a shielding cartridge comprising a metal outer pipe that surrounds at least a portion of an axial length of said metal inner pipe within said internal cavity, and wherein said thermally insulating end plate extends between said metal outer pipe and said plastic outer shell at least at one of said inlet and said outlet;
• and
• a Helmholtz chamber formed within said plastic outer shell.