Muffler for marine engine

Abstract

A marine engine muffler is provided having a silencing element with an inclined surface defining an array of elongate slotted apertures generally disposed in circumferential alignment. The slotted apertures are preferably defined by angled sidewalls such that exhaust gas flowing therethrough is forced to travel in a path that forms a reverse angle relative to the overall exhaust flow path thus conducting exhaust gases and entrained water to reverse direction while flowing through the silencing element. The conical silencing element is specifically sized to avoid resonant vibration within the operational RPM range of the engine and is further sized relative to the combined displacement of the engine and/or cylinder bank in fluid communication therewith to avoid resonant vibrations caused by reflected exhaust gas pressure waves generated by the internal combustion engine.

What I claim is:  
     
         1 . In a water-cooled exhaust gas system having an exhaust duct for conducting a flow of exhaust gases in an axial direction therethrough, said system including silencer element located within the exhaust duct, said silencer element having at least one apertured surface inclined to the flow of exhaust gas in the duct, wherein the improvement comprises the configuration of elongate slotted apertures defined by sidewalls disposed so as to direct exhaust gases in an upstream direction relative to said duct axis.  
     
     
         2 . A water-cooled exhaust gas system according to  claim 1 , wherein each slotted aperture has a length axis that is substantially perpendicular to the exhaust duct axis.  
     
     
         3 . A water-cooled exhaust gas system according to  claim 1 , wherein the slotted apertures are defined by elongate arcuate sidewalls.  
     
     
         4 . A water-cooled exhaust gas system according to  claim 1 , wherein said silencer element is generally conical and defines an internal volume of at least fifteen-times the combined volumetric displacement of the cylinders of any internal combustion engine in fluid connection therewith.  
     
     
         5 . A water cooled exhaust gas system according to  claim 1 , further including a second silencer element disposed in overlapping spaced downstream relation with said first silencer element, said first and second silencer elements each defining apertures therein, said first silencer element apertures being axially offset from said second silencer element apertures.  
     
     
         6 . A water cooled exhaust gas system according to  claim 1 , wherein said silencer element includes first and second baffle portions, said first baffle portion being inclined relative to the flow of exhaust gas, said second baffle portion being generally parallel to the flow of exhaust gas.  
     
     
         7 . A muffler for a marine engine exhaust system having an exhaust duct for conducting the flow of exhaust gases and entrained water from an engine downstream to the atmosphere, said muffler adapted for installation in the exhaust duct, said muffler comprising: 
 a silencing element having at least one surface thereof inclined with respect to the flow of exhaust gases through the exhaust conduit;    said silencing element defining a plurality of apertures, said apertures having an exhaust inlet and an exhaust outlet, said exhaust outlets disposed upstream relative to said exhaust inlets.    
     
     
         8 . A muffler for a marine engine exhaust system according to  claim 7 , wherein said silencing element is tubular.  
     
     
         9 . A muffler for a marine engine exhaust system according to  claim 7 , wherein said silencing element is conical.  
     
     
         10 . A muffler for a marine engine exhaust system according to  claim 7 , wherein said silencing element includes a portion thereof generally parallel to the flow path of exhaust gas.  
     
     
         11 . A muffler for a marine engine exhaust system according to  claim 7 , wherein said silencing element defines a volume corresponding to at least fifteen-times the corresponding cylinder displacement volume of the marine engine  
     
     
         12 . A muffler for a marine engine exhaust system according to  claim 7 , further including a second silencing element disposed in downstream relation relative to said first silencing element, said second silencing element including a plurality of apertures offset in a downstream direction relative to said first silencing element apertures.  
     
     
         13 . A muffler for a marine engine exhaust system, said exhaust system having an substantially cylindrical exhaust duct formed about a longitudinal axis for conducting the flow of exhaust gases and entrained water from an engine downstream to the atmosphere, said muffler adapted for installation in the exhaust duct, said muffler comprising: 
 a generally conical silencing element defining first and second arrays of apertures said first array of elongate apertures disposed toward a base portion of said conical silencing element and said second array of elongate apertures disposed on the remaining body portion of said conical silencing element;    said first array of apertures disposed angularly relative to the duct axis;    said second array of apertures disposed perpendicular relative to the duct axis.    
     
     
         14 . A muffler for a marine engine exhaust system according to  claim 13 , further including a third array of elongate apertures disposed generally perpendicular to said first array of apertures.