Intake air and carburetor heating arrangement for V-twin engines

Abstract

A V-twin engine having a crankcase and a pair of cylinders defining a V-space therebetween, wherein the V-space is substantially enclosed, and a carburetor is positioned within the V-space. An intake air preheating arrangement supplies heated intake air to the carburetor, and a carburetor heating arrangement heats the V-space and the carburetor which is positioned within the V-space. Each of the foregoing arrangements, used separately or in combination within one another, aids in preventing “freeze-up” of the carburetor during running of the engine in a cold environment.

1 . An internal combustion engine, comprising: 
 a crankcase having a crankshaft rotatably disposed therein;    a blower driven by said crankshaft to generate an air stream;    a pair of first and second cylinders connected to said crankcase;    an air intake system in fluid communication with said cylinders; and    an intake air heating arrangement, comprising: 
 a heater box disposed proximate said first cylinder, an interior of said heater box in airflow communication with said air stream; and  
 a conduit in airflow communication with said heater box and with said air intake system, whereby air from said air stream is heated within said heater box and is conducted through said conduit into said intake system of said engine.  
   
     
     
         2 . The engine of  claim 1 , wherein said first and second cylinders are disposed at an angle with respect to one another to define a V-space therebetween.  
     
     
         3 . The engine of  claim 2 , wherein said air intake system includes a carburetor, said carburetor disposed within said V-space.  
     
     
         4 . The engine of  claim 3 , wherein said air intake system further includes an air cleaner, said air cleaner connected to said carburetor and in airflow communication with said conduit.  
     
     
         5 . The engine of  claim 1 , wherein said heater box is connected to said first cylinder, said heater box disposed externally of said V-space.  
     
     
         6 . The engine of  claim 1 , further comprising a muffler in exhaust flow communication with said first cylinder and disposed proximate said heater box, whereby air from said air stream is heated within said heater box by heat from said muffler.  
     
     
         7 . The engine of  claim 1 , further comprising a cylinder wrap at least partially enclosing said first cylinder, said first cylinder and said cylinder wrap defining an air passage in airflow communication with said heater box through which said air stream is conducted.  
     
     
         8 . The engine of  claim 1 , wherein said crankshaft is disposed horizontally.  
     
     
         9 . A method of heating intake air in an engine which includes a pair of cylinders disposed at an angle with respect to one another to define a V-space therebetween, said method comprising the steps of: 
 generating an air stream;    conducting the air stream proximate a hot portion of the engine to heat air within the air stream;    capturing heated air from the air stream in a heater box; and    conducting heated air from the heater box to an intake system of the engine.    
     
     
         10 . The method of  claim 9 , wherein said first conducting step comprises conducting the air stream proximate at least one of a cylinder and a muffler of the engine.  
     
     
         11 . The method of  claim 9 , wherein said first conducting step further includes drawing heated air into the air stream from the vicinity of a muffler of the engine.  
     
     
         12 . The method of  claim 9 , wherein said second conducting step comprises conducting heated air from the heater box to a carburetor disposed within said V-space.  
     
     
         13 . An internal combustion engine, comprising: 
 a crankcase having a crankshaft rotatably disposed therein;    a blower driven by said crankshaft to generate an air stream;    a pair of cylinders connected to said crankcase, said cylinders disposed at an angle with respect to one another to define a V-space therebetween, said V-space substantially enclosed by portions of said engine;    a carburetor disposed within said V-space; and    a duct assembly disposed proximate at least one of said cylinders and in airflow communication with said air stream and with said V-space, whereby air in said air stream is heated within said duct assembly and is conducted to said V-space to heat said carburetor.    
     
     
         14 . The engine of  claim 13 , further comprising a muffler in exhaust flow communication with at least one of said cylinders and disposed proximate said duct assembly, said duct assembly further including an inlet disposed adjacent said muffler whereby heated air from the vicinity of said muffler is drawn by said air stream into said duct assembly.  
     
     
         15 . The engine of  claim 13 , further comprising a fuel tank disposed proximate an upper portion of said cylinders and a shroud disposed proximate a front side of said cylinders, said duct assembly including a wall disposed proximate a rear side of said cylinders, said fuel tank, shroud, and wall cooperating with one another to substantially enclose said V-space.  
     
     
         16 . The engine of  claim 13 , wherein said duct assembly includes a cylinder wrap at least partially enclosing said at least one cylinder, said at least one cylinder and said cylinder wrap defining an air passage in airflow communication with said V-space through which said air stream is conducted.  
     
     
         17 . The engine of  claim 13 , wherein said crankshaft is disposed horizontally.  
     
     
         18 . A method of heating a carburetor of an engine having a pair of cylinders which are disposed at an angle with respect to one another, said method comprising the steps of: 
 generating an air stream;    conducting the air stream proximate a hot portion of the engine to heat air within the air stream; and    conducting heated air from the air stream into a substantially enclosed V-space defined between the cylinders, in which the carburetor is positioned.    
     
     
         19 . The method of  claim 18 , wherein said first conducting step comprises conducting the air stream proximate at least one of a cylinder and a muffler of the engine.