Muffler and outlet stub for a muffler

Abstract

A muffler having a muffler housing with a muffler chamber formed therein includes an outlet stub. In the stub, a channel is formed through which exhaust gases escape. The channel has a throttle location with a smallest flow cross-section and a discharge opening with a discharge flow cross-section. The channel is bounded by a wall. The flow cross-section increases substantially continuously from the smallest flow cross-section to the discharge flow cross-section at least in a section in the direction from the throttle location to the discharge opening. The stub has a fastening location at which it is held in an outlet opening of the muffler housing. The wall is closed continuously over its circumference from the throttle location to the discharge opening. The section of the channel extends in a sectional plane containing a center axis of the channel into a longitudinal section of the stub having the fastening location.

1 . A muffler comprising:
 a muffler housing having at least one muffler chamber formed therein;   an outlet stub, in which an outlet channel is formed, through which exhaust gases escape from the muffler housing into an environment;   said outlet channel defining a center axis, a throttle location with a smallest flow cross-section, and a discharge opening with a discharge flow cross-section;   said outlet channel being bounded by an inner wall of said outlet stub;   said outlet channel having a flow cross-section which increases continuously from said smallest flow cross-section to said discharge flow cross-section at least in a section in a direction from said throttle location to said discharge opening;   said outlet stub having a fastening location at which said outlet stub is held in a housing discharge opening of said muffler housing;   said inner wall of the outlet stub being closed continuously over its entire circumference from said throttle location to said discharge opening; and,   said section of the outlet channel extending in a sectional plane containing said center axis into a longitudinal section of said outlet stub having said fastening location.   
     
     
         2 . The muffler of  claim 1 , wherein said outlet stub is held sealingly in said housing discharge opening at said fastening location. 
     
     
         3 . The muffler of  claim 1 , wherein said outlet stub has an outer thread with which said outlet stub is screwed into said muffler housing and which forms said fastening location. 
     
     
         4 . The muffler of  claim 1 , wherein said section of said outlet channel in which said flow cross-section of said outlet channel increases continuously in the direction from said throttle location to said discharge opening extends into the longitudinal section of said outlet stub; and, said longitudinal section is arranged upstream of said fastening location. 
     
     
         5 . The muffler of  claim 1 , wherein said inner wall of said outlet stub has a curved profile at least in one section from said fastening location to said discharge opening in a sectional plane containing said center axis. 
     
     
         6 . The muffler of  claim 1 , wherein said inner wall of said outlet stub has a continuously curved profile at least in one section from said fastening location to said discharge opening in a sectional plane containing said center axis. 
     
     
         7 . The muffler of  claim 1 , wherein a ratio of said discharge flow cross-section to said smallest flow cross-section is at least 3. 
     
     
         8 . The muffler of  claim 1 , wherein a ratio of said discharge flow cross-section to said smallest flow cross-section is at least 4, at least 5, or at least 6. 
     
     
         9 . The muffler of  claim 1 , wherein said outlet channel has a channel length, measured along said center axis, from a downstream end of said throttle location to said discharge opening; a ratio of said channel length to a channel diameter of said outlet channel at said discharge opening is at least 1; and, in a flow cross-section which is not circular, said channel diameter is a calculated diameter of a circular cross-section of identical area. 
     
     
         10 . The muffler of  claim 1 , wherein said outlet channel has a channel length, measured along said center axis, from a downstream end of said throttle location to said discharge opening; a ratio of said channel length to a channel diameter of said outlet channel at said discharge opening is at least 1.5; and, in a flow cross-section which is not circular, said channel diameter is a calculated diameter of a circular cross-section of identical area. 
     
     
         11 . The muffler of  claim 1 , wherein said outlet channel has a circular flow cross-section at least from a downstream end of said throttle location to said discharge opening. 
     
     
         12 . The muffler of  claim 1 , wherein said inner wall of said outlet stub encloses an angle (a) of not more than 30° with said center axis at said discharge opening in a sectional plane containing said center axis. 
     
     
         13 . The muffler of  claim 12 , wherein said angle (α) is not more than 30° from said throttle location to said discharge opening at each point of said inner wall. 
     
     
         14 . The muffler of  claim 1 , wherein said outlet stub includes a spark protection screen, which forms an inlet opening in said outlet stub; and, said outlet stub is formed by a one-piece base body and said spark protection screen. 
     
     
         15 . An outlet stub for a muffler, the outlet stub comprising:
 an outlet stub body defining an outlet channel through which exhaust gases can escape from a muffler housing into an environment;   said outlet channel defining a center axis, a throttle location with a smallest flow cross-section, and a discharge opening with a discharge flow cross-section;   said outlet channel being bounded by an inner wall of said outlet stub;   said outlet channel defining a flow cross-section which increases continuously from said smallest flow cross-section to said discharge flow cross-section at least in a section of said outlet channel in a direction from said throttle location to said discharge opening;   said outlet stub body having a fastening location at which the outlet stub is configured to be held in a housing discharge opening of the muffler housing;
 said inner wall being closed continuously over an entire circumference of said inner wall from said throttle location to said discharge opening; and, 
 said section extending in a sectional plane containing said center axis into a longitudinal section of said outlet stub having said fastening location.