Vehicle exhaust system

Abstract

An exhaust system for a straddle-type vehicle, such as a motorcycle, that is compact while also reducing noise output. The exhaust system communicates with an engine of an associated vehicle. The exhaust system includes an exhaust conduit, which is at least partially defined by an exhaust pipe, communicating with a combustion chamber of the engine. The exhaust system also includes a silencer. A ratio of a volume of the silencer to a volume of the exhaust conduit is between about 0.7 to 1.4. In some arrangements, the volume of the silencer and the volume of the exhaust conduit are substantially equal to each other.

1 . An exhaust system for a vehicle, comprising: 
 an exhaust conduit having a first end communicating with a combustion chamber of an engine of the vehicle; and    a silencer, a second end of the exhaust conduit communicating with the silencer;    wherein a ratio of a volume of the silencer to a volume of the exhaust conduit is between about 0.7 and about 1.4.    
   
   
       2 . The exhaust system of  claim 1 , wherein the ratio between the volume of the silencer and the volume of the exhaust conduit is selected to improve a noise damping characteristic of the exhaust system in a low frequency range.  
   
   
       3 . The exhaust system of  claim 1 , wherein a portion of the exhaust conduit is defined by an exhaust pipe and the ratio between the volume of the silencer and the volume of the exhaust conduit is selected to decrease a level of a primary resonance frequency of the exhaust pipe.  
   
   
       4 . The exhaust system of  claim 1 , further comprising a tail pipe communicating with the silencer, wherein the volume of the silencer is defined by an interior volume of the silencer minus a volume of the tail pipe that is within the interior volume of the silencer.  
   
   
       5 . The exhaust system of  claim 4 , wherein the volume of the exhaust conduit includes a volume of an exhaust port of the engine of the vehicle.  
   
   
       6 . The exhaust system of  claim 1 , wherein the volume of the silencer and the volume of the exhaust conduit are substantially equal.  
   
   
       7 . The exhaust system of  claim 1 , wherein the silencer comprises an outer housing and an inner core accommodated within the outer housing, and wherein at least a portion of the inner core includes a plurality of through-holes.  
   
   
       8 . The exhaust system of  claim 7 , wherein a sound absorbing material is positioned between an inner surface of the outer housing and an outer surface of the inner core of the silencer.  
   
   
       9 . The exhaust system of  claim 8 , further comprising a tail pipe communicating with the silencer, wherein an axis of the tail pipe is radially offset from an axis of the second end of the exhaust conduit that communicates with the silencer.  
   
   
       10 . The exhaust system of  claim 8 , wherein the sound absorbing material comprises at least one of glass wool and stainless steel wool.  
   
   
       11 . The exhaust system of  claim 1 , further comprising a tail pipe connected to the silencer, the silencer comprising an outer housing and an inner core within the outer housing, wherein an outside diameter of the tail pipe is smaller than an inside diameter of the inner core.  
   
   
       12 . The exhaust system of  claim 11 , wherein the inside diameter of the inner core gradually decreases from a forward end toward a rearward end, wherein the rearward end meets up with a forward end of the tail pipe.  
   
   
       13 . The exhaust system of  claim 11 , wherein an air space is provided between the tail pipe and the inner core.  
   
   
       14 . The exhaust system of  claim 1 , wherein the silencer comprises an outer housing and an inner core within the outer housing, and wherein a sound absorbing material is positioned between an inner surface of the outer housing and an outer surface of the inner core, further comprising a first air space between the inner surface of the outer housing and an outer surface of the sound absorbing material.  
   
   
       15 . The exhaust system of  claim 14 , further comprising a tail pipe connected to the silencer, wherein a second air space is provided between the tail pipe and the inner core, and the sound absorbing material is positioned between the second air space and the first air space.  
   
   
       16 . The exhaust system of  claim 1 , wherein a chamber is provided in the exhaust conduit, and a volume of the exhaust conduit includes a volume of the chamber.  
   
   
       17 . The exhaust system of  claim 1 , further comprising at least one conical member within the silencer, wherein a plurality of through-holes are formed in a wall of the conical member and each end of the conical member is open.  
   
   
       18 . The exhaust system of  claim 17 , wherein the silencer comprises an outer housing and an inner core within the outer housing, and wherein a tail pipe is connected to the inner core, the at least one conical member being positioned at an upstream end of the tail pipe.  
   
   
       19 . The exhaust system of  claim 18 , wherein an upstream opening of the at least one conical member is smaller than a downstream opening of the conical member.  
   
   
       20 . The exhaust system of  claim 17 , wherein the exhaust system includes a tail pipe connected to the silencer, the at least one conical member comprising a first conical member connected to the tail pipe and a second conical member connected to the inner core, wherein the second conical member overlaps at least a portion of the first conical member.  
   
   
       21 . A straddle-type vehicle, comprising: 
 an engine comprising at least one combustion chamber;    an exhaust conduit having a first end communicating with the combustion chamber; and    a silencer, a second end of the exhaust conduit communicating with the silencer;    wherein a ratio of a volume of the silencer to a volume of the exhaust conduit is between about 0.7 and about 1.4.    
   
   
       22 . The straddle-type vehicle of  claim 21 , wherein the volume of the exhaust conduit includes a volume of an exhaust port of the engine.  
   
   
       23 . The straddle-type vehicle of  claim 21 , wherein the engine operates on a four- stroke principle.  
   
   
       24 . The straddle-type vehicle of  claim 23 , wherein the vehicle is an off-road motorcycle.