FR2797488A1 - Fuel pipe especially for motor vehicle is made from two or more layers of different plastics produced by co-extrusion or covering - Google Patents

Abstract

The fuel pipe (1) is made from at least 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 rendered conducting by the addition of a filler to prevent the accumulation of electrostatic charges.

Description

The present invention relates to a fuel line, in particular for motor vehicles, comprising at least two layers, namely a first layer called inner layer coated with a second 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 second layer is made of non-crosslinkable PVC.

Advantageously, the inner layer and the second layer are joined together without intermediate bonding layer. Preferably, the thickness of the inner layer is less than 1 mm and the thickness of the second 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 second layer can be plasticized.

The pipe according to the invention can be obtained according to several manufacturing processes <B>: </ B> 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.

In an alternative embodiment, the pipe may comprise a reinforcing mesh and a covering layer provided on the second layer, said covering layer being made of a non-crosslinkable PVC of the same chemical nature as that used for the second layer.

The present invention and its advantages will appear better in the following description of two exemplary embodiments, with reference to the appended drawings, in which: FIG. 1 represents a perspective view of a pipe according to the invention, and FIG. represents a perspective view of an alternative embodiment.

The pipe 1 for transporting fuels shown in FIG. 1 comprises a first layer called inner layer 2 made of polyester or copolyester and a second layer, which is in this variant 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 a 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.

With reference to FIG. 2, the pipe 10 for the transport of fuel comprises a first layer called inner layer 12 made of polyester or copolyester and a second layer 13 made of non-crosslinkable PVC, covering the inner layer 12.

The polyester or copolyester, as well as the non-crosslinkable PVC used for this variant are identical to those used for the layers 2 and 3 described above for the embodiment shown in Figure 1. The resulting benefits are also identical.

In this variant, it is intended to cover the second layer 13 with a lattice 14 and a final covering layer 15.

The lattice 14 is composed of braided polyester yarns. The yarns can also be fiberglass or Kevlar. The mesh 14 makes it possible to increase the resistance to pressure, and therefore the bursting value of the pipe 10, especially at high temperatures. The mesh or the spacing of the wires must be weak to withstand the pressure but sufficient to let the covering layer 15 pass.

The final covering layer 15 is made of a non-crosslinkable PVC of the same chemical nature as that used for the second layer 13, in order to be able to bind to it by simple chemical adhesion. The different layers 12, 13 and 15 thus adhere to each other without intermediate bonding layer.

Without changing its chemical nature, the cover layer 15 may also contain charges for example to improve its fire resistance.

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

Claims (11)

claims 1. Pipe (1, 10) for fuels, in particular for motor vehicles, comprising at least two layers, namely a first layer called inner layer (2, 12) coated with a second layer (3, 13), characterized in that said inner layer (2, 12) is made of a material selected from polyester or copolyester and the second layer (3, 13) is of non-crosslinkable PVC. 2. Pipe according to claim 1, characterized in that the inner layer (2, 12) and the second layer (3, 13) are joined together without intermediate bonding layer. 3. Pipe according to claims 1 or 2, characterized in that the inner layer (2, 12) has a thickness of less than 1 mm. 4. Pipe according to claim 1 or 2, characterized in that the second layer (3, 13) 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, 12) is PBT. 6. Pipe according to any one of the preceding claims, characterized in that the non-crosslinkable PVC of the second layer (3, 13) 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. 11. Pipe (10) according to claim 1, characterized in that it comprises a lattice (14) and a final covering layer (15) provided on the second layer (13), said covering layer (15) being realized in a non-crosslinkable PVC of the same chemical nature as that used for the second layer (13).