Self-tuning exhaust muffler

Abstract

An exhaust muffler for a motor vehicle includes a louver tube having an intake end and an exhaust end. An outer tube, consisting of a frustoconical portion and a cylindrical portion, is concentrically arranged around the louver tube. A plurality of louvers and associated louver holes in the louver tube scoop a portion of gasses from the louver tube into the outer tube. An end cap, which includes an exhaust exit hole in its center, fits into an exhaust end of the outer tube. A plurality of end cap holes are arranged so that gasses leaving the outer tube flow through them. A restrictor disk between the end cap and louver tube includes a central hole coaxial with the louver tube and the exhaust exit hole of the end cap. Restrictor disk holes are in the restrictor disk between the central hole and its perimeter so that gasses leaving the louver tube flow through the central hole and the restrictor disk holes as they leave the muffler. A spiral vane defining a helical passage around the louver tube and inside the outer tube extends the path length of the gasses in the outer tube. A series of fins on the spiral vane extend orthogonal to an axis of the louver tube. A series of inner reverse cones are inside the louver tube upstream of its exhaust end. An exhaust system with this muffler is characterized by moderate backpressure at low rpms and little or negative backpressure at high rpms.

What is claimed is:  
     
         1 . An exhaust muffler for a motor vehicle, comprising: 
 a) a louver tube having an intake end and an exhaust end;    b) an outer tube concentrically arranged around said louver tube, said outer tube including a frustoconical portion and a cylindrical portion, said frustoconical portion connecting to said louver tube at said intake end such that a smallest cross-sectional area of said frustoconical portion is adjacent said intake end and a largest cross-sectional area of said frustoconical portion is adjacent said cylindrical portion;    c) a plurality of louvers and associated louver holes in said louver tube whereby a portion of gasses entering said louver tube are scooped into said outer tube by said louvers through said louver holes; and    d) an end cap fitting into an exhaust end of said outer tube; said end cap having 
 i) an exhaust exit hole in a center therein whereby gasses leaving said exhaust end of said louver tube flow through said exhaust exit hole, and  
 ii) at least one end cap hole therein whereby gasses leaving said outer tube flow through said at least one end cap hole wherein an exhaust flow from said vehicle is separated into first and second portions at an entry point of said muffler, and said first and second portions of said exhaust flow are combined downstream in said muffler.  
   
     
     
         2 . An exhaust muffler according to    claim 1   , further comprising a restrictor disk held against said exhaust end of said louver tube by said end cap, said restrictor disk having a central hole therein and at least one restrictor disk hole therein, whereby gasses leaving said exhaust end of said louver tube flow through said central hole and said at least one restrictor disk hole before exiting said exhaust exit hole of said end cap.  
     
     
         3 . An exhaust muffler according to    claim 1   , further comprising: 
 a spiral vane defining a helical passage around said louver tube and inside said outer tube; and    at least one fin on said spiral vane extending orthogonal to an axis of said louver tube.    
     
     
         4 . An exhaust muffler according to    claim 3   , wherein: 
 said spiral vane begins downstream of a first louver hole, said first louver hole being closest of all of said louver holes to said intake end of said louver tube; and    said spiral vane ends downstream of a last louver hole, said last louver hole being closest of all of said louver holes to said exhaust end of said louver tube.    
     
     
         5 . An exhaust muffler according to    claim 1   , further comprising at least one inner reverse cone inside said louver tube upstream of said exhaust end of said louver tube.  
     
     
         6 . An exhaust muffler according to    claim 1   , further comprising: 
 at least two end cap holes; and    at least one of said two end cap holes being threaded to receive a threaded plug.    
     
     
         7 . An exhaust muffler according to    claim 1   , wherein said motor vehicle is an automobile powered by one of an internal combustion engine or a turbo-charged diesel engine.  
     
     
         8 . An exhaust muffler according to    claim 1   , wherein said motor vehicle is a motorcycle.  
     
     
         9 . An exhaust muffler according to    claim 1   , wherein said motor vehicle is a truck powered by one of an internal combustion engine or a diesel engine.  
     
     
         10 . An exhaust muffler according to    claim 1   , wherein said motor vehicle is a piece of heavy equipment powered by a diesel engine.  
     
     
         11 . An exhaust muffler according to    claim 1   , wherein said louver tube is shaped as a cylinder and said cylindrical portion of said outer tube is congruent to said louver tube.  
     
     
         12 . An exhaust muffler for a motor vehicle, comprising: 
 a) a louver tube having an intake end and an exhaust end;    b) an outer tube concentrically arranged around said louver tube, said outer tube including a frustoconical portion and a cylindrical portion, said frustoconical portion connecting to said louver tube at said intake end;    c) a plurality of louvers and associated louver holes in said louver tube whereby a portion of gasses entering said louver tube are scooped into said outer tube by said louvers through said louver holes;    d) an end cap fitting into an exhaust end of said outer tube, said end cap having 
 i) an exhaust exit hole in a center therein whereby gasses leaving said exhaust end of said louver tube flow through said exhaust exit hole, and  
 ii) at least one end cap hole therein whereby gasses leaving said outer tube flow through said at least one end cap hole;  
   e) a restrictor disk held against said exhaust end of said louver tube by said end cap, said restrictor disk having a central hole therein and at least one restrictor disk hole therein, whereby gasses leaving said exhaust end of said louver tube flow through said central hole and said at least one restrictor disk hole before exiting said exhaust exit hole of said end cap;    f) a spiral vane defining a helical passage around said louver tube and inside said outer tube; and    g) at least one inner reverse cone inside said louver tube upstream of said exhaust end of said louver tube.    
     
     
         13 . An exhaust muffler according to    claim 1   , further comprising: 
 (e) a spiral vane defining a helical passage around said louver tube and inside said outer tube.    
     
     
         14 . An exhaust muffler according to    claim 1   , further comprising: 
 (e) at least one inner reverse cone inside said louver tube upstream of said exhaust end of said louver tube.    
     
     
         15 . An exhaust muffler for a motor vehicle, comprising: 
 a) a louver tube having an intake end and an exhaust end;    b) an outer tube concentrically arranged around said louver tube, said outer tube including a frustoconical portion and a cylindrical portion, said frustoconical portion connecting to said louver tube at said intake end such that a smallest cross-sectional area of said frustoconical portion is adjacent said intake end and a largest cross-sectional area of said frustoconical portion is adjacent said cylindrical portion;    c) a plurality of louvers and associated louver holes in said louver tube whereby a portion of gasses entering said louver tube are scooped into said outer tube by said louvers through said louver holes; and    d) an end cap fitting into an exhaust end of said outer tube; said end cap having at least one end cap hole therein whereby gasses leaving said outer tube flow through said at least one end cap hole wherein an exhaust flow from said vehicle is separated into first and second portions at an entry point of said muffler, and said first and second portions of said exhaust flow are combined downstream in said muffler.    
     
     
         16 . An exhaust muffler according to    claim 15   , wherein said end cap includes an exhaust exit hole in a center therein whereby gasses leaving said exhaust end of said louver tube flow through said exhaust exit hole.  
     
     
         17 . An exhaust muffler according to    claim 15   , further comprising: 
 (e) a restrictor disk held against said exhaust end of said louver tube by said end cap, said restrictor disk having at least one hole therein.    
     
     
         18 . An exhaust muffler according to    claim 17   , further comprising: 
 (f) at least one inner reverse cone inside said louver tube upstream of said exhaust end of said louver tube.    
     
     
         19 . An exhaust muffler according to    claim 15   , further comprising: 
 (e) at least one inner reverse cone inside said louver tube upstream of said exhaust end of said louver tube.    
     
     
         20 . An exhaust muffler for a motor vehicle, comprising: 
 means for separating an exhaust flow from said vehicle into first and second portions at an entry point of said muffler;    means for combining said first and second portions of said exhaust flow downstream in said muffler;    wherein a first path length of said first portion of said exhaust flow is longer than a second path length of said second portion of said exhaust flow.    
     
     
         21 . A muffler according to    claim 20   , wherein said first and second portions of said exhaust stream are combined at an exhaust exit point of said muffler.