Closure system

Abstract

The invention relates to a closure system on a fuel tank ( 2 ) of thermoplastics with barrier properties for hydrocarbons. The closure system comprises at least one orifice ( 4 ), with a closure cap ( 5 ) which closes the orifice ( 4 ) in a sealing manner and which cooperates in a form-fitting manner with closure means provided at the circumference of the orifice ( 4 ) and encloses at least one first sealing means between it and a tank wall ( 3 ). The closure system ( 1 ) according to the invention is distinguished in that the tank wall is sealed in the region of the orifice ( 4 ) with at least one second sealing means, which covers and/or shields a part of the tank wall surfaces exposed to hydrocarbons.

What is claimed is: 
     
         1 .- 13 . (canceled) 
     
     
         14 . A fuel tank closure system, comprising:
 a fuel tank to hold hydrocarbon fuel, the fuel tank having a tank wall of thermoplastics with a barrier layer for hydrocarbons, with at least one orifice having a circumference;   a closure cap fastenable to the fuel tank to close the orifice;   at least one first seal enclosed between the closure cap and an outer surface of the tank wall when the closure cap is fastened to the fuel tank; and   at least one second seal which is supported by the tank wall on the tank wall in a region of the orifice when the orifice is open, the at least one seal covers or shields a part of the tank wall exposed to hydrocarbon fuel when placed in the fuel tank; and   wherein the orifice has an edge with a circumferential face defined by a cross-sectional thickness of the tank wall, and the second seal covers or shields the cross-sectional thickness of the tank wall defining the circumferential face of the edge of the orifice from exposure to the hydrocarbon fuel;   wherein the second seal comprises an elastomeric ring in the orifice; and   wherein the elastomeric ring comprises a sealing skirt which covers or shields the circumferential face of the edge of the orifice.   
     
     
         15 . The closure system according to  claim 14 , wherein the second seal comprises a surface covering on the tank wall, which is restricted to covering a surface of the tank wall in the region of the orifice. 
     
     
         16 . The closure system according to  claim 15 , wherein the surface covering comprises a coating. 
     
     
         17 . The closure system according to  claim 16 , wherein the coating is a plasma coating. 
     
     
         18 . The closure system according to  claim 16 , wherein the coating is a finish coating. 
     
     
         19 . The closure system according to  claim 14 , wherein the second seal comprises a surface treatment of the tank wall, which is restricted to treating the tank wall in the region of the orifice. 
     
     
         20 . The closure system according to  claim 19 , wherein the surface treatment comprises at least one of fluorination and sulphonation. 
     
     
         21 . The closure system according to  claim 14 , wherein the closure cap comprises a collar which protrudes into the orifice and the collar comprises at least one circumferential sealing lip, which covers the circumferential face of the edge of the orifice. 
     
     
         22 . The closure system according to  claim 21 , wherein the sealing lip is captively fastened to the closure cap. 
     
     
         23 . The closure system according to  claim 21 , wherein the sealing lip is injection moulded onto the closure cap. 
     
     
         24 . The closure system according to  claim 14 , wherein the closure system comprises a bayonet closure. 
     
     
         25 . The closure system according to  claim 14 , wherein the closure cap cooperates with a closure means of the fuel tank to close the orifice. 
     
     
         26 . The closure system according to  claim 25  wherein the closure means is provided at the circumference of the orifice and configured such the closure cap is fastenable to the fuel tank. 
     
     
         27 . The closure system according to  claim 26  wherein the closure means comprises at least one bayonet ring, which is moulded into the tank wall. 
     
     
         28 . The closure system according to  claim 27 , wherein the bayonet ring comprises a plurality of retaining claws. 
     
     
         29 . The closure system according to  claim 14 , wherein the second seal is formed of rubber. 
     
     
         30 . The closure system according to  claim 29 , wherein the rubber is fluorine rubber.