Vented fuel tank cap

Abstract

A vented fuel tank cap for closing the filler neck portion of a fuel tank for a small gasoline powered implement. The fuel tank cap assembly includes a cap member having threads for removably attaching the cap assembly to the fuel tank filler neck. The cap member also includes a post depending from an interior of the cap member. The cap assembly further including a gasket having an annular rim surrounding a dome portion and an opening. The opening of the gasket is disposed on the post and retained by a rib protruding externally from the post. The gasket dome portion is deformed by the rib so that the annular rim is held in contact with the interior surface of the cap member. A vent path is provided through the post to vent fuel vapors from below a lower surface of the gasket, through a filter element captured between the gasket dome and the interior surface of the cap member, through a groove defined between the gasket annular rim and the interior surface of the cap member, and out through a space defined between the threads retaining the cap member to the filler neck.

What is claimed is:  
     
         1 . A vented fuel tank cap assembly, comprising: 
 a cap member including a circular cap portion and a downwardly depending skirt portion, said skirt portion including an engagement portion for removably attaching the cap assembly to a filler neck portion of a fuel tank, said cap portion including a cylindrical post depending from an interior of said cap portion, said post having at least one rib extending exteriorly around at least a portion thereof; and    a gasket having an annular rim surrounding a dome portion and an opening in said dome portion, wherein said opening fits around said post and said rib retains said gasket to said cap member.    
     
     
         2 . The vented fuel tank cap assembly of  claim 1 , further comprising a porous filter element disposed between said dome portion of said gasket and said interior of said cap portion, wherein said filter element transmits fuel vapors and is generally impervious to liquid fuel.  
     
     
         3 . The vented fuel tank cap assembly of  claim 2 , wherein said rib deforms said dome portion of said gasket compressing said filter element between said dome portion and said interior of said cap portion.  
     
     
         4 . The vented fuel tank cap assembly of  claim 1 , wherein said engagement portion comprises threads cooperating to retain the fuel cap to said fuel tank while providing a vent path therethrough.  
     
     
         5 . The vented fuel tank cap assembly of  claim 1 , further comprising a vent path for venting gases between the fuel tank and the atmosphere defined by said post from an end of said post opposite said interior of said cap portion to a point between said dome portion and said interior of said cap portion.  
     
     
         6 . The vented fuel tank cap assembly of  claim 5 , wherein: 
 said annular rim contacts said interior of said cap portion; and    at least one vent path is defined between said annular rim and said interior of said cap portion.    
     
     
         7 . The vented fuel tank cap assembly of  claim 5 , wherein said post comprises a tube and said vent path comprises a slot defined through a wall of said tube.  
     
     
         8 . A vented fuel tank cap assembly, comprising: 
 a cap member including a circular cap portion and a downwardly depending skirt portion, said skirt portion including a nonsealing thread for removably attaching the cap assembly to the filler neck portion, said cap portion including a tubular post depending from an interior of said cap portion, an interior surface of said tubular post defining a first deflection surface and a first vent path; and    a gasket having an annular rim surrounding a dome portion and an opening defined in said dome portion, said opening engaged around said tubular post, said gasket and an exterior surface of said tubular post defining a second deflection surface, said annular rim contacting said interior of said cap portion and forming at least one second vent path therebetween.    
     
     
         9 . The vented fuel tank cap assembly of  claim 8 , wherein said first vent path comprises a slot defined through a wall of said tubular post.  
     
     
         10 . The vented fuel tank cap assembly of  claim 8 , wherein said at least one second vent path is formed by at least one radial groove defined between an upper surface of said annular rim and said interior of said cap portion.  
     
     
         11 . The vented fuel tank cap assembly of  claim 8 , wherein said post defines a rib protruding externally around a portion thereof, said rib retaining said gasket to said cap member.  
     
     
         12 . The vented fuel tank cap assembly of  claim 8 , further comprising a porous filter element disposed between said dome portion of said gasket and said interior of said cap portion, wherein said filter element transmits fuel vapors and is generally impervious to liquid fuel.  
     
     
         13 . The vented fuel tank cap assembly of  claim 12 , wherein said rib deforms said dome portion of said gasket, compressing said filter element between said dome portion and said interior of said cap portion.  
     
     
         14 . A vented fuel tank cap assembly, comprising: 
 a cap member including a circular cap portion and a downwardly depending skirt portion, said skirt portion including an engagement portion for removably attaching the cap assembly to a filler neck portion of a fuel tank, said cap portion including a post depending from an interior of said cap portion; and    a circular gasket having an opening defined therethrough, an upper surface engageable with said interior of said cap portion, and a lower surface opposite said upper surface, said opening disposed around said post;    said post defining a first vent path for communication of gases adjacent said lower surface with gases adjacent said upper surface.    
     
     
         15 . The vented fuel tank cap assembly of  claim 14 , wherein said post comprises a tube and said vent path comprises a slot defined through a wall of said tube.  
     
     
         16 . The vented fuel tank cap assembly of  claim 14 , wherein said at least one second vent path is formed by at least one radial groove defined between an upper surface of said annular rim and said interior of said cap portion.  
     
     
         17 . The vented fuel tank cap assembly of  claim 14 , wherein said post defines a rib around an external portion thereof, said rib retaining said gasket to said cap member.  
     
     
         18 . The vented fuel tank cap assembly of  claim 17 , further comprising a porous filter element disposed between said gasket and said interior of said cap portion, wherein said filter element transmits fuel vapors and is generally impervious to liquid fuel.  
     
     
         19 . The vented fuel tank cap assembly of  claim 18 , wherein: 
 said gasket further comprises a dome portion; and    said rib captures said filter element between said dome portion and said interior of said cap portion.    
     
     
         20 . The vented fuel tank cap assembly of  claim 14 , wherein said engagement portion comprises threads cooperating to retain the fuel cap to said fuel tank while providing a vent path therethrough.  
     
     
         21 . In combination: 
 a fuel tank having a fuel tank neck portion; and    a fuel tank cap having: 
 a cap member including a circular cap portion and a downwardly depending skirt portion, said skirt portion including an engagement portion for removably attaching said cap to said filler neck portion, said cap portion including a tubular post depending from an interior of said cap portion, said tubular post having at least one rib extending exteriorly around at least a portion thereof; and  
 a gasket having an annular rim surrounding a dome portion and an opening in said dome portion, wherein said opening fits around said tubular post and said rib retains said gasket to said cap member.