Method of producing an insulated exhaust device

Abstract

A method for producing an exhaust gas aftertreatment or acoustic device ( 20 ) having a maximum operating temperature T MAX . The method includes the steps of (a) providing a blanket ( 40 ) of silica fiber insulation material having a weight percentage of SiO 2 greater than 65%; (b) calcining the insulating material by heating the blanket ( 40 ) so that all of silica fiber insulation material is raised to a temperature T greater than T MAX (where T is less than the melting temperature of the silica fibers of the blanket); and (c) securing the blanket ( 40 ) on the device ( 20 ) after the calcining step. The blanket is encapsulated in a covering ( 50 ) prior to the calcining step whereby the blanket is batting in the covering, with the covering between the blanket and the device being a selected one of wire mesh or siliconized fiber glass.

1 . A method of providing external insulation for an exhaust gas aftertreatment or acoustic device having a maximum operating temperature T MAX , the method comprising:
 providing a blanket of silica fiber insulation material having a weight percentage of SiO 2  of greater than 65%;   calcining the blanket by heating all of the silica fiber insulation material to a temperature T greater than T MAX , wherein T is less than a melting temperature of the silica fibers of the blanket;   encapsulating said blanket in a covering before the calcining step whereby said blanket is batting in said covering; and   securing the blanket around an outermost surface of the exhaust gas aftertreatment or acoustic device after the calcining step;   wherein said covering between said blanket and said exhaust gas aftertreatment or acoustic device is a selected one of wire mesh or high temperature textile.   
     
     
         2 . The method of  claim 1  wherein T is at least 1.05×T MAX . 
     
     
         3 . The method of  claim 1 , wherein said high temperature textile is a selected one of siliconized fiber glass or straight woven glass fiber. 
     
     
         4 . The method of  claim 1  wherein during the calcining step the blanket is in an uncompressed state. 
     
     
         5 . The method of  claim 1  wherein T MAX  is within a range of 300° C. to 1100° C. 
     
     
         6 . The method of  claim 1 , wherein the securing step comprises installing the blanket so that the blanket encircles a core of the device through which the exhaust gas passes. 
     
     
         7 . A method of providing external insulation for an exhaust gas aftertreatment or acoustic device having a maximum operating temperature T MAX , the method comprising:
 providing a blanket of silica fiber insulation material having a weight percentage of SiO 2  of greater than 95%;   calcining the blanket by heating all of the silica fiber insulation material to a temperature T greater than T MAX , wherein T is less than a melting temperature of the silica fibers of the blanket;   encapsulating said blanket in a covering before the calcining step whereby said blanket is batting in said covering; and   securing the blanket around an outermost surface of the exhaust gas aftertreatment or acoustic device after the calcining step;   wherein said covering between said blanket and said exhaust gas aftertreatment or acoustic device is a selected one of wire mesh or high temperature textile.   
     
     
         8 . The method of  claim 7  wherein T is at least 1.05×T MAX . 
     
     
         9 . The method of  claim 7 , wherein said high temperature textile is a selected one of siliconized fiber glass or straight woven glass fiber. 
     
     
         10 . The method of  claim 7  wherein during the calcining step the blanket is in an uncompressed state. 
     
     
         11 . The method of  claim 7  wherein T MAX  is within a range of 300° C. to 1100° C. 
     
     
         12 . The method of  claim 7 , wherein the securing step comprises installing the blanket so that the blanket encircles a core of the device through which the exhaust gas passes. 
     
     
         13 . A method of providing external insulation for an exhaust gas aftertreatment or acoustic device having a maximum operating temperature T MAX , the method comprising:
 providing a blanket of silica fiber insulation material having a weight percentage of SiO 2  of greater than 65%;   calcining the blanket in an uncompressed state by heating all of the silica fiber insulation material to a temperature T greater than T MAX , wherein T is less than a melting temperature of the silica fibers of the blanket and is at least 1.05×T MAX  and T MAX  is within a range of 300° C. to 1100° C.;   encapsulating said blanket in a covering before the calcining step whereby said blanket is batting in said covering; and   securing the blanket around an outermost surface of the exhaust gas aftertreatment or acoustic device after the encapsulating step;   wherein said covering between said blanket and said exhaust gas aftertreatment or acoustic device is a selected one of wire mesh or high temperature textile.   
     
     
         18 . The method of claim  17 , wherein said high temperature textile is a selected one of siliconized fiber glass or straight woven glass fiber. 
     
     
         19 . The method of claim  17 , wherein the securing step comprises installing the blanket so that the blanket encircles a core of the device through which the exhaust gas passes.