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 fuel tank cap assembly, comprising: 
 a cap member including a downwardly depending skirt portion and a hollow post depending from an interior surface of said cap member, said post having an external surface; and    a gasket having a rim portion and an opening, said opening engaging said external surface of said post to retain said gasket to said cap member.    
     
     
         2 . The fuel tank cap assembly of  claim 1 , wherein said external surface of said post includes at least one rib, said opening of said gasket engaging said at least one rib to retain said gasket to said cap member.  
     
     
         3 . The fuel tank cap assembly of  claim 2 , wherein said gasket is dimensioned such that said engagement of the opening thereof with said rib of said post presses said rim portion of said gasket into engagement with said interior surface of said cap member.  
     
     
         4 . The fuel tank cap assembly of  claim 1 , wherein an interior portion of said hollow post is in fluid communication with a space defined between said gasket and said cap member to define a vent path therebetween.  
     
     
         5 . The fuel tank cap assembly of  claim 4 , wherein said hollow post includes an opening therein fluidly communicating said interior of said hollow post with said space between said gasket and said cap member.  
     
     
         6 . The fuel tank cap assembly of  claim 4 , wherein said rim portion of said gasket includes at least one recess defining a vent path between said rim portion and said interior surface of said cap member.  
     
     
         7 . The fuel tank cap assembly of  claim 1 , further comprising a porous filter element disposed between said gasket and said interior surface of said cap member, said filter element allowing passage of air and fuel vapor therethrough but substantially preventing passage of liquid fuel therethrough.  
     
     
         8 . The fuel tank cap assembly of  claim 7 , wherein said gasket is dimensioned such that engagement thereof with said post compresses said filter element between said gasket and said interior surface of said cap member.  
     
     
         9 . The fuel tank cap assembly of  claim 1 , wherein said gasket further includes a depending wall portion substantially surrounding said hollow post of said cap member.  
     
     
         10 . The fuel tank cap assembly of  claim 1 , wherein said skirt portion of said cap member is circular, and includes internal threads.  
     
     
         11 . A fuel tank cap assembly, comprising: 
 a cap member including a downwardly depending skirt portion and a hollow post depending from an interior surface of said cap member, said post having an external surface; and    a gasket having an opening engaging said external surface of said post to retain said gasket to said cap member, said gasket further including a wall portion depending therefrom which substantially surrounds said post.    
     
     
         12 . The fuel tank cap assembly of  claim 11 , wherein said external surface of said post includes at least one rib, said opening of said gasket engaging said at least one rib to retain said gasket to said cap member.  
     
     
         13 . The fuel tank cap assembly of  claim 11 , wherein said gasket includes a rim portion, said gasket dimensioned such that said engagement of the opening thereof with said post presses said rim portion of said gasket into engagement with said interior surface of said cap member.  
     
     
         14 . The fuel tank cap assembly of  claim 11 , further comprising a porous filter element disposed between said gasket and said interior surface of said cap member, said filter element allowing passage of air and fuel vapor therethrough but substantially preventing passage of liquid fuel therethrough.  
     
     
         15 . The fuel tank cap assembly of  claim 14 , wherein said gasket is dimensioned such that engagement thereof with said post compresses said filter element between said gasket and said interior surface of said cap member.  
     
     
         16 . The fuel tank cap assembly of  claim 11 , wherein said hollow post includes an opening therein, said opening fluidly communicating an interior portion of said hollow post with a space defined between said gasket and said cap member to define a vent path therebetween.  
     
     
         17 . The fuel tank cap assembly of  claim 11 , wherein said skirt portion of said cap member is circular, and includes internal threads.  
     
     
         18 . In combination: 
 a fuel tank having a filler neck; and    a fuel tank cap removably attached to said filler neck, said fuel tank cap comprising: 
 a cap member including a downwardly depending skirt portion and a hollow post depending from an interior surface of said cap member, said post having an external surface; and  
 a gasket including an opening engaging said external surface of said post to retain said gasket to said cap member.  
   
     
     
         19 . The combination of  claim 18 , wherein said filler neck includes external threads and said skirt portion of said fuel tank cap includes internal threads, said threads engaging one another to secure said fuel tank cap to said filler neck.  
     
     
         20 . The combination of  claim 18 , wherein said gasket further includes a rim portion disposed under compression between said filler neck and said interior surface of said cap member.  
     
     
         21 . The combination of  claim 18 , wherein said external surface of said post includes at least one rib, said opening of said gasket engaging said at least one rib to retain said gasket to said cap member.  
     
     
         22 . The combination of  claim 18 , wherein said hollow post includes an opening therein, said opening fluidly communicating an interior portion of said hollow post with a space defined between said gasket and said cap member to define a vent path therebetween.  
     
     
         23 . A fuel tank cap assembly, comprising: 
 a cap member including a downwardly depending skirt portion and a hollow post depending from an interior surface of said cap member; and    a gasket attached to said cap member, said gasket having a wall portion depending therefrom which substantially surrounds said post.    
     
     
         24 . The fuel tank cap assembly of  claim 23 , wherein said hollow post includes an opening therein, said opening fluidly communicating an interior portion of said hollow post with a space defined between said gasket and said cap member to define a vent path therebetween.  
     
     
         25 . The fuel tank cap assembly of  claim 24 , further comprising a porous filter element disposed between said gasket and said interior surface of said cap member, said filter element allowing passage of air and fuel vapor therethrough but substantially preventing passage of liquid fuel therethrough.  
     
     
         26 . The fuel tank cap assembly of  claim 23 , wherein said post includes an external surface with at least one rib, said gasket includes opening engaging said at least one rib to retain said gasket to said cap member.  
     
     
         27 . The fuel tank cap assembly of  claim 26 , wherein said gasket includes a rim portion, said gasket dimensioned such that said engagement of the opening thereof with said post presses said rim portion of said gasket into engagement with said interior surface of said cap member.