Catalytic converter and method for manufacture thereof

Abstract

A system and method for the manufacture of a laser-welded cone-shell catalytic converter ( 100 ) is provided. An unformed shell blank ( 111 ) is formed into a cylindroid shell ( 110 ) having overlapping edges ( 112 ), which are then resistance welded to produce a shell seam ( 116 ). The shell seam ( 116 ) is planished to a thickness ( 120 ) less than 125 percent of a thickness ( 119 ) of the unformed shell blank ( 111 ). A ceramic catalytic substrate ( 130 ) is wrapped in a ceramic-fiber mounting mat ( 131 ) and inserted into the shell ( 110 ). Ends ( 125 ) of the shell ( 110 ) are crimped to form a 1 mm turndown ( 134 ). A pair of endcones ( 140 ) is assembled, where for each endcone ( 140 ) an outer cone ( 141 ) is loaded with an endcone insulation ( 142 ), and an inner cone ( 143 ) is pressed into and spot-welded to the outer cone ( 141 ). The endcones ( 140 ) are fitted to the shell ( 110 ) so as to form an overlap zone ( 151 ). The endcones ( 140 ) and shell ( 110 ) are then laser welded by an Nd:YAG laser ( 253 ) in the overlap zone ( 151 ).

1 . A catalytic converter comprising: 
 a shell;    a ceramic catalytic substrate loaded into said shell;    an endcone fit to said shell; and    a bead formed by laser welding said endcone to said shell.    
   
   
       2 . A catalytic converter as claimed in  claim 1  wherein said shell comprises: 
 a shell blank formed into a cylindroid; and    a gas-tight shell seam formed by welding edges of said shell blank together.    
   
   
       3 . A catalytic converter as claimed in  claim 2  wherein said shell seam is planished to a thickness greater than a thickness of said shell blank and no more than 125 percent of said thickness of said shell blank.  
   
   
       4 . A catalytic converter as claimed in  claim 1  wherein said shell comprises a turndown section at each end of said shell.  
   
   
       5 . A catalytic converter as claimed in  claim 1  additionally comprising a ceramic-fiber mounting mat wrapped around said ceramic catalytic substrate.  
   
   
       6 . A catalytic converter as claimed in  claim 1  wherein said endcone comprises: 
 an outer cone;    an endcone insulation loaded into said outer cone; and    an inner cone pressed into and welded to said outer cone.    
   
   
       7 . A catalytic converter as claimed in  claim 1  wherein: 
 said catalytic converter additionally comprises a cylindroid overlap zone between said endcone and said shell; and    said bead is formed in said cylindroid overlap zone.    
   
   
       8 . A catalytic converter as claimed in  claim 7  wherein said bead exhibits a bead width that is less than a zone width of said cylindroid overlap zone.  
   
   
       9 . A catalytic converter as claimed in  claim 8  wherein said bead width is no greater than fifty percent of said zone width.  
   
   
       10 . A catalytic converter as claimed in  claim 7  wherein said bead is a first bead, and said catalytic converter further comprises a second bead formed by said laser welding in said cylindroid overlap zone.  
   
   
       11 . A catalytic converter as claimed in  claim 1  wherein: 
 said catalytic converter additionally comprises a converter assembly formed when said endcone is fitted to said shell; and    said bead is formed while said converter assembly is rotated.    
   
   
       12 . A catalytic converter as claimed in  claim 1  wherein said bead is formed by a laser beam from a neodymium-yttrium-aluminum-garnet laser.  
   
   
       13 . A catalytic converter as claimed in  claim 1  wherein: 
 a first one of said endcone and said shell constitutes a first layer;    a second one of said endcone and said shell constitutes a second layer; and    said bead is formed by a laser beam, said laser beam penetrating one hundred percent of said first layer, and said laser beam penetrating at between forty and ninety percent of said second layer.    
   
   
       14 . A catalytic converter as claimed in  claim 13  wherein said laser beam penetrates substantially seventy-five percent of said second layer.