Sound muffling material and method of making thereof

Abstract

A sound muffling material for use in combustion engine exhaust mufflers is provided. The material includes volumized fibers retained in compressed form by a material of lower softening temperature than the fibers. When the material is heated by exhaust gases, the material of lower softening temperature is softened allowing the compressed fibers to expand. The fibers may be formed into a knitted fabric retained by a sacrificial thread. The material may be used to support catalyst bricks.

1. A sound muffling material comprising volumized continuous filament fibers retained in a compressed state in the form of a knitted or woven fabric with a density of at least 200 kg/m 3  60 kg/m 3  by a material of lower softening temperature than the fibers, arranged so that the material of lower softening temperature will release the fibers when heated. 
     
     
       2. A sound muffling material comprising volumized continuous filament fibers retained in a compressed state in the form of a knitted or woven fabric with a density of at least 200 kg/m 3  60 kg/m 3  by a material which breaks down at a lower temperature than the fibers, arranged so that the material of lower softening temperature will release the fibers when heated, wherein the average length of the fibers is greater than 400 mm. 
     
     
       3. The sound muffling material according to  claim 1  wherein the fibers comprise glass fibers. 
     
     
       4. The sound muffling material according to  claim 1  wherein the fibers are resistant to thermal breakdown up to 1000° C. 
     
     
       5. The sound muffling material according to  claim 1  wherein the fibers are retained by a material selected from the group consisting of nylon, polypropylene, polyethylene or polyester. 
     
     
       6. The sound muffling material according to  claim 1  wherein the fibers are retained by a material with a softening or melting temperature below 200° C. 
     
     
       7. The sound muffling material according to  claim 1  wherein the material of lower softening temperature than the fibers is itself a fiber. 
     
     
       8. The sound muffling material according to  claim 1  wherein the material of lower softening temperature than the fibers is a sacrificial catch thread. 
     
     
       9. The sound muffling material according to  claim 1  wherein the fabric has a density of at least 400 kg/m 3  in compressed form. 
     
     
       10. The sound muffling material according to  claim 1  wherein the fabric has a density of the order of 600 kg/m 3  in compressed form. 
     
     
       11. The A method of filling an exhaust muffler with fibers comprising the steps of:
 providing a material including volumized continuous filament fibers retained in a compressed state in the form of a knitted or woven fabric with a density of at least  200 kg/m 3  60 kg/m 3  by a material of lower softening temperature than the fibers, arranged so that the material of lower softening temperature will release the fibers when heated; 
 placing the material into an exhaust muffler; and 
 heating the material so as to soften the retaining material to release the fibers, wherein the average length of the fibers is greater than 400 mm. 
 
     
     
       12. A method of filling an exhaust muffler with fibers, comprising the steps of:
 providing a material including volumized continuous filament fibers retained in a compressed state in the form of a knitted or woven fabric with a density of at least 200kg/m 3  60 kg/m 3  by a material which breaks down at a lower temperature than the fibers, arranged so that the material of lower softening temperature will release the fibers when heated; 
 placing the material into an exhaust muffler; and 
 heating the material so as to cause the retaining material to breakdown to release the fibers, wherein the average length of the fibers is greater than 400 mm. 
 
     
     
       13. A method of mounting an exhaust catalyst brick, comprising the steps of:
 providing a material including volumized continuous filament fibers retained in a compressed state in the form of a knitted or woven fabric with a density of at least 200kg/m 3  60 kg/m 3  by a material of lower softening temperature than the fibers, arranged so that the material of lower softening temperature will release the fibers when heated: 
 wrapping the brick in the material; and 
 heating the material so as to soften the retaining material to release the fibers. 
 
     
     
       14. A method of mounting an exhaust catalyst brick, comprising the steps of:
 providing a material including volumized continuous filament fibers retained in a compressed state in the form of a knitted or woven fabric with a density of at least 200 kg/m 3  60 kg/m 3  by a material which breaks down at a lower temperature than the fibers, arranged so that the material of lower softening temperature will release the fibers when heated: 
 wrapping the brick in the material; and 
 heating the material so as to cause the retaining material to breakdown to release the fibers. 
 
     
     
       15. The method according to  claim 13  further comprising the step of inserting the wrapped brick into a box, before heating the material. 
     
     
       16. A method of making a sound muffling material comprising the steps of providing continuous filament fibers, volumizing said fibers, providing a material with a lower softening temperature than the fibers, compressing said volumized fibers and retaining said volumized in a compressed state by means of the material of lower softening temperature by forming said volumized fibers into a knitted or woven fabric with a density of at least 200 kg/m 3  60 kg/m 3 , wherein the average length of the fibers is greater than 400mm. 
     
     
       17. A method of making a sound muffling material comprising the steps of providing continuous filament fibers, volumizing said fibers, providing a material with a lower breakdown temperature than the fibers, compressing said volumized fibers and retaining said volumized in a compressed state by means of the material of lower breakdown temperature by forming said volumized fibers into a knitted or woven fabric with a density of at least 200 kg/m 3 . 60 kg/m 3 , wherein the average length of the fibers is greater than 400 mm. 
     
     
       18. The method according to  claim 16  wherein the fibers are provided in the form of multi-filament strands. 
     
     
       19. A The method according to  claim 18  wherein the multi-filament strands comprise multiple fibre roving. 
     
     
       20. The method according to  16  wherein the fibers are volumized using compressed air operated volumizing equipment. 
     
     
       21. The method according to  claim 16  wherein the volumizing step increases the volume occupied by the fibers by at least a factor of ten. 
     
     
       22. The method according to  claim 14  further comprising the step of inserting the wrapped brick into a box, before heating the material. 
     
     
       23. The method according to  claim 17  wherein the fibers are provided in the form of multi-filament strands. 
     
     
       24. The method according to  claim 17  wherein the fibers are volumized using compressed air operated volumizing equipment. 
     
     
       25. The method according to  claim 17  wherein the volumizing step increases the volume occupied by the fibers by at least a factor of ten. 
     
     
       26. The sound muffling material according to  claim 2  wherein the fibers comprise glass fibers. 
     
     
       27. The sound muffling material according to  claim 3  wherein the average length of the fibers is greater than 400 mm. 
     
     
       28. The sound muffling material according to  claim 2  wherein the fibers are resistant to thermal breakdown up to 1000° C. 
     
     
       29. The sound muffling material according to  claim 2  wherein the fibers are retained by a material selected from the group consisting of nylon, polypropylene, polyethylene or polyester, and combinations thereof. 
     
     
       30. The sound muffling material according to  claim 2  wherein the fibers are retained by a material with a softening or melting temperature below 200° C. 
     
     
       31. The sound muffling material according to  claim 2  wherein the material of lower softening temperature than the fibers is itself a fibre fiber. 
     
     
       32. The sound muffling material according to  claim 2  wherein the material of lower softening temperature than the fibers is a sacrificial catch thread. 
     
     
       33. The sound muffling material according to  claim 2  wherein the fabric has a density of at least 400 kg/m 3  in compressed form. 
     
     
       34. The sound muffling material according to  claim 2  wherein the fabric has a density of the order of 600 kg/m 3  in compressed form. 
     
     
       35. A sound muffling material comprising volumized continuous filament fibers retained in a compressed state in the form of a knitted or woven fabric with a density of at least 200kg/m 3  60 kg/m 3  by a material of lower softening temperature than the fibers, arranged so that the material of lower softening temperature will release the fibers when heated, wherein the average length of the fibers is greater than 400 mm. 
     
     
       36. The sound muffling material according to claim 1 wherein the fabric has a density of at least 200 kg/m 3  in compressed form. 
     
     
       37. The sound muffling material according to claim 2 wherein the fabric has a density of at least 200 kg/m 3  in compressed form. 
     
     
       38. The sound muffling material according to claim 11 wherein the fabric has a density of at least 200 kg/m 3  in compressed form. 
     
     
       39. The sound muffling material according to claim 12 wherein the fabric has a density of at least 200 kg/m 3  in compressed form. 
     
     
       40. The sound muffling material according to claim 13 wherein the fabric has a density of at least 200 kg/m 3  in compressed form. 
     
     
       41. The sound muffling material according to claim 14 wherein the fabric has a density of at least 200 kg/m 3  in compressed form. 
     
     
       42. The sound muffling material according to claim 16 wherein the fabric has a density of at least 200 kg/m 3  in compressed form. 
     
     
       43. The sound muffling material according to claim 17 wherein the fabric has a density of at least 200 kg/m 3  in compressed form. 
     
     
       44. The sound muffling material according to claim 35 wherein the fabric has a density of at least 200 kg/m 3  in compressed form.