Fuel tank and method for making same

1. A process for manufacturing a plastic fuel tank, said process comprising: forming a fuel tank with a wall defining at least one opening: placing at least one accessory at least partly outside the fuel tank such that said fuel tank and said accessory form an interface between said fuel tank and said accessory: forming a thin film of multilayer structure that includes at least one fuel barrier layer that is impermeable to gaseous and liquid fuels, said thin film having a flexibility substantially greater than that of said wall of said fuel tank; placing said thin film over said interface between said fuel tank and said accessory so that said fuel tank is sealed from an outside atmosphere at said interface by said fuel barrier layer of said thin film: and welding an entire outer periphery of the thin film directly to the tank around said opening of said fuel tank thereby connecting a first part of the film directly to the accessory such that the thin film extends across a seam between the accessory and the tank, wherein said forming of the thin film is preformed by thermoforming, independently of the forming of the fuel tank, before the welding of the thin film to the fuel tank.

2. The process according to claim 1 , further comprising, before the welding of the thin film to the fuel tank, pressing the thin film against the at least one accessory and the wall of the tank in a vicinity of the at least one accessory by a stream of hot air.

3. A process according to claim 1 , wherein said welding of the thin film to the fuel tank is performed by laser radiation welding.

4. A process according to claim 1 , wherein said welding of the thin film to the fuel tank is performed by infrared radiation welding.

5. The process according to claim 1 , wherein said forming of the thin film comprises incorporating a non-barrier layer to said multilayered structured, the method further comprising thinning a portion of said non-barrier layer around the outer periphery of the thin film over a distance at least equal to a width of a welding region.

6. The process according to claim 1 , wherein the forming of the thin film comprises incorporating a composition opaque to a laser radiation or to infrared radiation into a layer of the thin film to be directly in contact with the wall of the fuel tank.

7. The process according to claim 1 , wherein the forming of the thin film comprises incorporating into the film at least one layer containing a polyolefin.

8. A process for manufacturing a plastic fuel tank, said process comprising: forming a fuel tank with a wall defining at least one opening; placing at least one accessory at least partly outside the fuel tank such that said fuel tank and said accessory form an interface between said fuel tank and said accessory; forming a thin film of multilayer structure that includes at least one fuel barrier layer that is impermeable to gaseous and liquid fuels, said thin film having a flexibility substantially greater than that of said wall of said fuel tank; placing said thin film over said interface between said fuel tank and said accessory so that said fuel tank is sealed from an outside atmosphere at said interface by said fuel barrier layer of said thin film; and welding an entire outer periphery of the thin film directly to the tank around said opening of said fuel tank thereby connecting a first part of the film directly to the accessory such that the thin film extends across a seam between the accessory and the tank, wherein the placing of said thin film is performed such that the thin film completely covers the at least one accessory to remove any direct contact between the at least one accessory and said outside atmosphere.

9. The process according to claim 1 , wherein the at least one accessory comprises a pipe that opens the atmosphere external to the fuel tank, and wherein the placing of said thin film is performed such that the thin film allows only the pipe to run out into the external atmosphere.

10. The process according to claim 1 , wherein: the forming of said thin film comprises forming an opening in said thin film, said thin film opening being defined by an inner periphery for said thin film, and the placing of said thin film is performed such that said thin film extends from said inner periphery of said thin film.

11. The process according to claim 10 , wherein the placing of said thin film is performed such that said thin film includes a portion between said inner periphery and said outer periphery that is not bonded to said fuel tank nor to said at least one accessory.

12. The process according to claim 1 , wherein the placing of said thin film is performed such that said thin film includes a portion that seals said interface, wherein said portion is not directly bonded to said fuel tank nor to said accessory.

13. The process according to claim 1 , wherein the placing of said thin film is performed such that said thin film has a portion with said fuel barrier layer over said interface, wherein said portion of said film is not bonded to said fuel tank nor to said accessory.

14. The process according to claim 10 , wherein the placing of said thin film is performed such that said interface is sealed by said fuel barrier layer of said thin film around an entire periphery of said interface around said fuel tank.

15. A process for manufacturing a plastic fuel tank, said process comprising: forming a fuel tank with a wall defining at least one opening: placing at least one accessory at least partly outside the fuel tank such that said fuel tank and said accessory form an interface between said fuel tank and said accessory; forming a thin film of multilayer structure that includes at least one fuel barrier layer that is impermeable to gaseous and liquid fuels, said thin film having a flexibility substantially greater than that of said wall of said fuel tank; placing said thin film over said interface between said fuel tank and said accessory so that said fuel tank is sealed from an outside atmosphere at said interface by said fuel barrier layer of said thin film; and welding an entire outer periphery of the thin film directly to the tank around said opening of said fuel tank thereby connecting a first part of the film directly to the accessory such that the thin film extends across a seam between the accessory and the tank, wherein said accessory includes an accessory fuel barrier layer that at least partially covers said opening of said fuel tank, and wherein said fuel barrier layer of said thin film covers said accessory fuel barrier layer so that said accessory fuel barrier layer and said fuel barrier layer of said thin film provide a double sealing for said opening of said fuel tank.

16. The process according to claim 1 , wherein said accessory is attached to said fuel tank such that said interface between said fuel tank and said accessory has a portion outside said fuel tank and said fuel barrier layer of said thin film seals said portion of said interface outside said fuel tank.

17. The process according to claim 1 , wherein the placing of the thin film includes placing the thin film in direct contact with an outermost surface of the tank and in direct contact with an outermost surface of the accessory.

18. The process according to claim 17 , wherein the first part of the film overlaps the accessory and the tank so as to sandwich the accessory between the first part and the tank, and

a second part of the film does not overlap the accessory.

19. A process for manufacturing a plastic fuel tank, said process comprising:

forming a fuel tank with a wall defining at least one opening;

placing at least one accessory at least partly outside the fuel tank such that said fuel tank and said accessory form an interface between said fuel tank and said accessory;

forming a thin film of multilayer structure that includes at least one fuel barrier layer that is impermeable to gaseous and liquid fuels, said thin film having a flexibility substantially greater than that of said wall of said fuel tank;

placing said thin film over said interface between said fuel tank and said accessory so that said fuel tank is sealed from an outside atmosphere at said interface by said fuel barrier layer of said thin film; and

welding an entire outer periphery of the thin film directly to the tank around said opening of said fuel tank thereby connecting a first part of the film directly to the accessory such that the thin film extends across a seam between the accessory and the tank,

wherein the placing of the thin film includes placing the thin film in direct contact with an outermost surface of the tank and in direct contact with an outermost surface of the accessory,

wherein the thin film is not directly bonded to the accessory.

20. The process according to claim 1 , wherein the placing at least one accessory at least partly outside the fuel tank includes welding the accessory directly to the tank.

21. The process according to claim 1 , wherein the placing at least one accessory at least partly outside the fuel tank includes mechanically coupling the accessory directly to the tank.

22. The process according to claim 21 , wherein the mechanically coupling includes threading the accessory in combination with the tank.