Free-standing internally insulating liner

Abstract

An insulating liner for use with exhaust system or pollution control devices such as catalytic converters and diesel particulate filters or traps. The insulating liner is shown in relation to an end cone for use with a catalytic converter. The end cone includes an outer metallic end cone and a free-standing insulating cone positioned within the outer metallic end cone. A substantial portion of the inner surface of the insulating liner is exposed to hot exhaust gas from an internal combustion engine. The insulating liner is preferably formed of a composite containing inorganic fibers and/or particles, which makes the insulating liner rigid, yet capable of withstanding repeated mechanical and thermal shocks.

What is claimed is:  
     
         1 . An article comprising a molded, self-supporting insulating cone having dimensions suitable for use in an end cone region of a pollution control device, said insulating cone comprising inorganic materials comprising inorganic fibers, inorganic particles, or combinations thereof, wherein the inorganic materials are bound together.  
     
     
         2 . The article of  claim 1 , wherein the inorganic material comprises inorganic fibers comprising alumina-boria-silica, alumna-silica, alumina-phosphorous pentoxide, zirconia-silica, zirconia-alumina, or alumina.  
     
     
         3 . The article of  claim 1 , wherein the inorganic material comprises inorganic fibers prepared using a sol gel process.  
     
     
         4 . The article of  claim 1 , wherein the inorganic material comprises inorganic particles comprising clays, ceramic or glass powders, ceramic or glass beads, or hollow ceramic or glass spheres.  
     
     
         5 . The article of  claim 1 , wherein the insulating cone further comprising an organic binder.  
     
     
         6 . The article of  claim 1 , wherein the insulating cone further comprises an inorganic binder.  
     
     
         7 . The article of  claim 6 , wherein the inorganic binder comprises an alumina, colloidal silica, silicon carbide, or monoaluminum phosphate.  
     
     
         8 . The article of  claim 6 , wherein the inorganic binder is applied to one surface of the molded, self-supporting insulating cone.  
     
     
         9 . The article of  claim 1 , wherein the inorganic material comprises ceramic fibers and glass fibers.  
     
     
         10 . A method of forming a self-supporting insulating cone, said method comprising: 
 preparing a mold having the shape and dimensions of an end cone for a pollution control device;    forming a mixture comprising inorganic materials and an optional binder, said inorganic material comprising inorganic fibers, inorganic particles, or a combination thereof;    binding together the inorganic materials in the mixture;    placing the mixture in the mold; and    molding the inorganic material into a three-dimensional shaped insulation material.    
     
     
         11 . The method of  claim 10 , wherein the inorganic material comprises inorganic fibers comprising alumina-boria-silica, alumna-silica, alumina-phosphorous pentoxide, zirconia-silica, zirconia-alumina, or alumina.  
     
     
         12 . The method of  claim 10 , wherein the inorganic material comprises at least one inorganic fiber prepared using a sol gel process.  
     
     
         13 . The method of  claim 10 , wherein the inorganic material comprises inorganic particles comprising clays, ceramic or glass powders, ceramic or glass beads, or hollow ceramic or glass spheres.  
     
     
         14 . The method of  claim 10 , wherein the mixture further comprises an organic binder.  
     
     
         15 . The method of  claim 10 , wherein the mixture comprises ceramic fibers and further comprises an organic binder.  
     
     
         16 . The method of  claim 10 , wherein the mixture further comprises an inorganic binder.  
     
     
         17 . The method of  claim 16 , wherein the inorganic binder comprises an alumina, colloidal silica, silicon carbide, or monoaluminum phosphate.  
     
     
         18 . The method of  claim 10 , wherein the inorganic material comprises ceramic fibers and glass fibers.  
     
     
         19 . The method of  claim 10 , further comprising brushing a refractory coating or solution onto a surface of the three-dimensional insulation material.  
     
     
         20 . A method of forming a free-standing fibrous end cone for positioning within a metallic end cone of a pollution control device, the method comprising: 
 providing a mold having the dimensions of the inside surface of an outer metal end cone portion of a pollution control device; 
 saturating strips of a ceramic fiber mat with a colloidal silica suspension;  
 laying the saturated ceramic fiber strips on the inside surface of the mold;  
 compressing the saturated ceramic fiber strips against the mold to provide the desired outer and inner diameter of the insulating end cone; and  
 removing the fibrous insulating end cone from the mold.