Fuel Cap and Filler Neck

Abstract

A fuel cap is disclosed that contains a flexible hemispherical closure member which is substantially compressible and resilient with a form approximating half of a sphere. The circular face of the hemispherical sealing member is coupled to the underside of the fuel cap. Sealing of the fuel tank is obtained where the flexible member contacts the inner surface of the filler neck. The flexible sealing member includes a section of rigid tubing aligned coaxially to the axis of the fuel cap to serve as a vent tube for safety. The vent tube penetrates the flexible sealing member, and the upper portion of the vent tube penetrates the top portion of the cap. Inset into the cap top portion and covering the end of the tube section is a meltout plug. The cap may alternately include a compression washer mounted to the end of the vent tubing, for use with filler necks where the inside circumference contains a ridge. Where the washer contacts the filler neck ridge when the cap is installed, it is pushed up against and compresses the flexible sealing member when installed in the filler neck. The compression of the flexible sealing member provides additional sealing of the fuel cap against the filler neck inside surface.

1 . A fuel cap and fuel filler neck system comprising:
 (a) a fuel cap comprising a top portion, a circumferential skirt extending from said top portion, and a flexible hemispherical sealing member coupled to the underside of said fuel cap; and   (b) a fuel filler neck where said flexible hemispherical sealing member closes and seals the inside opening of said fuel filler neck when the fuel cap is applied.   
   
   
       2 . The fuel cap and fuel filler neck system of  claim 1 , where
 (a) said fuel cap includes a vent tube that extends axially through said flexible hemispherical sealing member and through the top portion of said fuel cap; and   (b) a metal melt-out plug covering the top portion of said vent tube.   
   
   
       3 . The fuel cap and fuel filler neck system of  claim 2  where
 (a) said fuel filler neck is bounded by an annular shoulder at its upper end and has a plurality of protrusions along the outer perimeter of said annular shoulder; and   (b) said fuel cap has a plurality of recesses in an interior section of the cap along the said circumferential skirt, where said plurality of recesses couple with said plurality of protrusions on said fuel filler tube.   
   
   
       4 . The fuel cap and fuel filler neck system of  claim 3 , where
 (a) a compression washer is movably attached to said vent tube, and   (b) said filler neck includes a ridge on its interior circumferential surface, whereby said ridge causes said compression washer to compress said flexible hemispherical sealing member when said fuel cap is applied to said fuel filler neck.   
   
   
       5 . The fuel cap and fuel filler neck system of  claim 2  where
 (a) said fuel cap supports screw threads in its interior face of the circumferential skirt; and   (b) said fuel filler neck supports screw threads on its outer perimeter, whereby the fuel cap screw threads secure said fuel cap by coupling with the filler neck screw threads.   
   
   
       6 . The fuel cap and fuel filler neck system of  claim 5 , where
 (a) a compression washer is movably attached to said vent tube, and   (b) said filler neck includes a ridge on its interior circumferential surface, whereby said ridge causes said compression washer to compress said flexible hemispherical sealing member when said fuel cap is applied to said fuel filler neck.