368results about "Sound absorption" patented technology

An exhaust system for a vehicular positive ignition internal combustion engine comprises a filter for filtering particulate matter from exhaust gas emitted from the engine, which filter comprising a porous substrate having inlet and outlet surfaces, wherein the inlet surfaces are separated from the outlet surfaces by a porous structure containing pores of a first mean pore size, wherein the porous substrate is coated with a three-way catalyst washcoat comprising a plurality of solid particles wherein the porous structure of the washcoated porous substrate contains pores of a second mean pore size, which is less than the first mean pore size, and a three-way catalyst washcoat disposed on a separate substrate monolith located upstream of the filter, wherein a mass of three-way catalyst washcoat on the upstream substrate monolith is ≦75% of the total mass of three-way catalyst washcoat in the exhaust system.

An absorption muffler includes a metallic exhaust pipe including a plurality of perforations, a polymeric housing carried by the exhaust pipe and enclosing the plurality of perforations, and including axially opposed ends. Thermal insulation is carried radially between the exhaust pipe and the polymeric housing and axially between the axially opposed ends inclusive thereof. Acoustic insulation is carried between the thermal insulation and the polymeric housing.

The use of fiber metal or similarly high flow resistance and high acoustic transparency material as a liner for traditional acoustically absorptive media in a dissipative muffler exhibits improved low frequency sound attenuation, reduces backpressure, and eliminates media entrainment or "blow-out" phenomenon which results in longer muffler life. The same class of materials may also be used to fashion an element that provides linear occlusion inside an otherwise line-of-sight type of muffler, where the occluding element provides improved impedance-matching acoustic absorption. Disclosed embodiments providing linear occlusion minimize traditional increases in muffler backpressure by incorporating helical, conical, and annular members in mufflers with round ducts. To maximize attenuation, a muffler according to the invention may feature both a fiber metal fill liner and a fiber metal linear occlusion element. Further, the liner that connects the inlet and outlet ports of the muffler may feature an offset, elbow, or turn that would simultaneously allow it to provide means for linear occlusion.

A method for filling a muffler with a fibrous material is disclosed. The muffler includes partitions which form a first chamber and second chamber, and a first muffler pipe having an outlet end. A filling aperture at one end of the second muffler pipe is positioned in the first muffler chamber. The second muffler pipe has a filling sleeve therein, the filling sleeve having a filling discharge opening that coordinates with the filling aperture of the second muffler pipe. The first muffler chamber is filled with fibrous material by applying a vacuum source to the first muffler pipe, which draws the fibrous material through the filling aperture. The filling aperture of the second muffler pipe is then positioned into the second muffler chamber, and the second muffler chamber is filled in the same manner as the first muffler chamber. The filling sleeve is then removed from the second muffler pipe.

A mat material includes inorganic fibers, a first surface, and a second surface opposite to the first surface. The mat material has plural needle traces formed by performing a needling treatment. The needle traces extend from the first surface toward the second surface and from the second surface toward the first surface. There is no depth in the mat material that the needle traces do not reach. There is substantially no protrusion of a bundle of the inorganic fibers at a position on the second surface that lies on a line extending from each of the needle traces extending from the first surface. There is substantially no protrusion of a bundle of the inorganic fibers at a position on the first surface that lies on a line extending from each of the needle traces extending from the second surface.