Combination muffler and spark arrester

Abstract

An improved combination muffler and spark arrester for an exhaust system of an internal combustion engine includes a muffler section, a diverging inlet pipe section that defines, optionally in combination with the muffler section, an enlarged volume, and a spark arrester screen extending across the entire flow path to the muffler section. This combination provides effective spark arresting without impeding exhaust flow, and therefore without any significant adverse effect on performance.

1 . A combination muffler and spark arrester for an exhaust systems of an internal combustion engine, comprising: 
 a muffler section;    a diverging inlet pipe section that defines, optionally in combination with the muffler section, an enlarged volume; and    a spark arrester screen at least partially disposed within the enlarged volume, the spark arrester screen extending across the entire flow path to the muffler section.    
   
   
       2 . The combination muffler and spark arrester of  claim 1 , wherein the spark arrester screen has a conical shape.  
   
   
       3 . The combination muffler and spark arrester of  claim 1 , further comprising an inlet flow diverter disposed within the enlarged volume downstream of the spark arrester screen.  
   
   
       4 . The combination muffler and spark arrester of  claim 1 , wherein the spark arrester screen is completely disposed within the enlarged volume.  
   
   
       5 . The combination muffler and spark arrester of  claim 1 , wherein the muffler section includes an imperforate outer shell, a perforated intermediate shell spaced inwardly of the outer shell, sound absorbing material disposed within a first volume defined between the outer shell and the intermediate shell, a perforated inner shell spaced inwardly of the intermediate shell, sound absorbing material disposed within a second volume defined by the inner shell, the inner shell and the intermediate shell defining an annular space for flow of exhaust gases from an inlet end of the muffler section to an outlet end of the muffler section.  
   
   
       6 . A combination muffler and spark arrester for an exhaust system of an internal combustion engine, comprising: 
 a muffler section;    a diverging inlet pipe section that defines, optionally in combination with the muffler section, an enlarged volume; and    a spark arrester screen disposed completely within the enlarged volume.    
   
   
       7 . The combination muffler and spark arrester of  claim 6 , wherein the spark arrester screen has a conical shape  
   
   
       8 . The combination muffler and spark arrester of  claim 6 , further comprising an inlet flow diverter disposed within the enlarged volume downstream of the spark arrester screen.  
   
   
       9 . The combination muffler and spark arrester of  claim 6 , wherein the spark arrester screen extends across the entire flow path to the muffler section.  
   
   
       10 . The combination muffler and spark arrester of  claim 6 , wherein the muffler section includes an imperforate outer shell, a perforated intermediate shell spaced inwardly of the outer shell, sound absorbing material disposed within a first volume defined between the outer shell and the intermediate shell, a perforated inner shell spaced inwardly of the intermediate shell, sound absorbing material disposed within a second volume defined by the inner shell, the inner shell and the intermediate shell defining an annular space for flow of exhaust gases from an inlet end of the muffler section to an outlet end of the muffler section.  
   
   
       11 . A combination muffler and spark arrester for an exhaust system of an internal combustion engine, comprising: 
 a muffler section including an imperforate outer shell, a perforated intermediate shell spaced inwardly of the outer shell, sound absorbing material disposed within a first volume defined between the outer shell and the intermediate shell, a perforated inner shell spaced inwardly of the intermediate shell, sound absorbing material disposed within a second volume defined by the inner shell, the inner shell and the intermediate shell defining an annular space for flow of exhaust gases from an inlet end of the muffler section to an outlet end of the muffler section;    a diverging inlet pipe section that defines, optionally in combination with the muffler section, an enlarged volume; and    a spark arrester screen at least partially disposed within the enlarged volume.    
   
   
       12 . The combination muffler and spark arrester of  claim 11 , wherein the spark arrester screen has a conical shape.  
   
   
       13 . The combination muffler and spark arrester of  claim 11 , further comprising an inlet flow diverter disposed within the enlarged volume downstream of the spark arrester screen.  
   
   
       14 . The combination muffler and spark arrester of  claim 11 , wherein the spark arrester screen is completely disposed within the enlarged volume.  
   
   
       15 . The combination muffler and spark arrester of  claim 11 , wherein the spark arrester screen extends across the entire flow path to the muffler section.