FR2797489A1 - Fuel pipe especially for motor vehicle is made from two layers of different plastics produced by co-extrusion or covering - Google Patents

Abstract

The fuel pipe (1) is made from two layers - an inner layer (2) and an outer layer (3), produced by co-extrusion or covering and having no intermediate connecting layer. The thickness of the inner layer is less than 1 mm, while that of the outer layer is between 0.5 and 3 mm. The pipe can have an optional third inner layer (4) of plastic with a filler to make it conducting and prevent the accumulation of electrostatic charges.

Description

The present invention relates to a fuel line, in particular for motor vehicles, comprising an inner layer and an outer layer. Until now, multilayer pipes have been used, which include - either barrier materials, among which PVdF, ETFE ... whose main disadvantage is their high price; - Or less noble materials, such as PA6, but which is a poor barrier to fuels including alcohol.

In both cases, the fire resistance is not satisfactory. It can be improved by a recovery operation, but this operation leads to a consequent increase in the cost price.

The present invention aims to overcome these disadvantages by providing a pipeline that offers better performance than those obtained with current techniques both in terms of permeability to fuels than in terms of fire resistance and with a lower cost.

For this purpose, the invention relates to a pipe of the kind indicated in the preamble, characterized in that the inner layer is made of a material selected from polyester or copolyester, and in that the outer layer is made of non-crosslinkable PVC.

Advantageously, the two inner and outer layers are joined together without intermediate bonding layer.

Preferably, the thickness of the inner layer is less than 1 mm and the thickness of the outer layer is between 0.5 and 3 mm. In a particularly advantageous manner, the polyester or copolyester used for the inner layer is PBT. On the other hand, the non-crosslinkable PVC used for the outer layer can be plasticized.

The pipe according to the invention can be obtained according to several manufacturing processes: by coextrusion and overlay.

It is possible to provide a third conductive layer inside the inner layer. This third layer may also be polyester or copolyester, made conductive by the addition of fillers.

The present invention and its advantages will appear better in the following description of an exemplary embodiment, with reference to the appended drawing, wherein the single figure shows a perspective view of a pipe according to the invention. The pipe 1 for transporting fuels shown in the single figure comprises an inner layer 2 made of polyester or copolyester and an outer layer 3 made of non-crosslinkable PVC, which adheres to said inner layer 2 without intermediate bonding layer.

The polyester or copolyester used is PBT (polybutylene terephthalate), in particular of the GRILPET type from EMS. Any other suitable polyester or copolyester can also be used.

The non-crosslinkable PVC may optionally be plasticized. For example, a non-crosslinkable PVC of the SUNPRENE type from RESINOPLAST can be used.

Preferably, the inner layer 2 has a thickness of less than 1 mm and the outer layer 3 has a thickness of between 0.5 and 3 mm. The pipe 1 may also comprise a third layer 4 inside the inner layer 2, made of a polyester or copolyester rendered electrically conductive by the addition of charges. This third conductive layer 4 makes it possible to avoid any problem due to an accumulation of electrostatic charges.

Line 1 can be manufactured by coextrusion or overlay. The combination of a polyester or copolyester with a non-crosslinkable PVC offers the following advantages - the small thickness of the inner layer 2 gives the pipe 1 a good flexibility - the use of the polyester or copolyester makes it possible to obtain good impermeability to alcoholic essences and better durability - the use of a non-crosslinkable PVC in a thickness adapted to the needs, offers an excellent resistance to fire. In addition, it can be additive of charges retarding the combustion.

- PVC allows the pipe to resist perfectly thermal and chemical aggressions (due to brake and cooling fluids, grease and oil) present under the hood of an engine.

The present invention is not limited to the embodiment described but extends to any modification and variation obvious to a person skilled in the art.

Claims (10)

<U> Claims </ U> Pipe (1) for fuels, in particular for motor vehicles, comprising an inner layer (2) and an outer layer (3), characterized in that said inner layer (2) is made of a material chosen from polyester or the copolyester and in that the outer layer (3) is of non-crosslinkable PVC. 2. Sewer according to claim 1, characterized in that the two inner layers (2) and outer (3) are joined together without intermediate bonding layer. 3. Sewer according to claims 1 or 2, characterized in that the inner layer (2) has a thickness of less than 1 mm. 4. Pipe according to claim 1 or 2, characterized in that the outer layer (3) has a thickness of between 0.5 and 3 mm. 5. Pipeline according to any one of the preceding claims, characterized in that the polyester or copolyester used for the inner layer (2) is PBT. 6. Pipe according to any one of the preceding claims, characterized in that the non-crosslinkable PVC of the outer layer (3) is plasticized. 7. Pipe according to any one of the preceding claims, characterized in that it is manufactured by coextrusion. 8. Pipe according to any one of the preceding claims, characterized in that it is manufactured by covering. 9. Pipe according to claim 1, characterized in that it comprises a third layer (4) conductive inside the inner layer (2). 10. Sewer according to claim 9, characterized in that said third layer (4) is polyester or copolyester made conductive by the addition of charges.