Holding Web for an Exhaust Gas Processing Unit, Associated Device, Production Method and Exhaust Line

Abstract

The web ( 8 ) is arranged around a processing unit ( 14 ) between the processing unit ( 14 ) and an envelop ( 16 ) which defines a conduit ( 12 ) for the exhaust gas flow. The web ( 18 ) includes a mattress whose external side is provided with an aluminosilicate-containing coating ( 30 ). The invention is used for motor vehicle exhaust lines.

1 - 12 . (canceled)  
   
   
       13 . A support sheet for supporting a member for treating exhaust gas from an engine, the sheet being for placing around the treatment member between the treatment member and a casing defining an exhaust gas flow duct, the sheet comprising a mat presenting an external coating; 
 wherein the coating comprises an aluminosilicate.    
   
   
       14 . A sheet according to  claim 13 , wherein the aluminosilicate comprises an alumina silicophosphate.  
   
   
       15 . A sheet according to  claim 13 , wherein the aluminosilicate comprises 40% to 60% by weight silicon oxide, 10% to 30% by weight phosphorous oxide, and 10% to 30% by weight aluminum oxide, relative to the total weight of aluminosilicate.  
   
   
       16 . A sheet according to  claim 13 , wherein the aluminosilicate further comprises 5% to 10% by weight sodium oxide and/or potassium oxide and 0.5% to 2% by weight iron oxide relative to the total weight of aluminosilicate.  
   
   
       17 . A sheet according to  claim 13 , wherein the aluminosilicate comprises a poly(silicon-oxo-aluminate) presenting motifs having the general formula:  
       M n [—(SiO 2 ) a —(AlO 2 )—] n    
     in which: 
   n  is an integer greater than 1;  
   a  is an integer in the range 1 to 30; and  
 M is a cation selected from Na + , K + , Li + , Ca 2+ , Ba 2+ , H 3 O + , and mixtures thereof.  
 
   
   
       18 . A sheet according to  claim 13 , wherein the coating can be obtained by a method of applying an aqueous dispersion on the body of the sheet, the aqueous dispersion presenting a dry extract lying in the range 20% to 50%.  
   
   
       19 . A device for treating engine exhaust gas, the device comprising: 
 a casing defining an exhaust flow duct;    at least one treatment member disposed in the duct; and    a sheet according to  claim 13 , the sheet being disposed between the treatment member and the casing, around the treatment member.    
   
   
       20 . A device according to  claim 19 , wherein the sheet has an upstream transverse face and a downstream transverse face, both substantially perpendicular to a longitudinal axis of the treatment member, at least one of the upstream and downstream transverse faces presenting said coating.  
   
   
       21 . A device according to  claim 19 , wherein the sheet presents two side faces bearing respectively against the casing and the treatment member, at least one of the side faces presenting said coating.  
   
   
       22 . A method of manufacturing a device according to  claim 19 , the method comprising the steps of: 
 coating a face of the sheet at least in part using a binder comprising an aluminosilicate in order to form a coating;    applying the sheet against the treatment member; and    placing the treatment member and the sheet in the casing.    
   
   
       23 . A method according to  claim 22 , wherein the face is coated by spraying on the binder.  
   
   
       24 . An exhaust system, including a device according to  claim 19.