WO2007042536A1

WO2007042536A1 - Fuel tank filler pipe

Info

Publication number: WO2007042536A1
Application number: PCT/EP2006/067278
Authority: WO
Inventors: Patrice Chiron; Jacques Covet
Original assignee: Inergy Automotive Systems Research (Societe Anonyme)
Priority date: 2005-10-14
Filing date: 2006-10-11
Publication date: 2007-04-19
Also published as: FR2892068A1; CN101287619A; FR2892068B1

Abstract

Filler pipe for a fuel tank, comprising: a filler head (2) made of a conductive plastic; a pipe body (1), and an earth wire (3) connecting the filler head to an electrical earth point of a vehicle. The earth wire is also made of a conductive plastic.

Description

Fuel tank filler pipe

The present invention relates to a fuel tank filler pipe. Fuel systems for motor vehicles generally comprise a fuel tank and a filler pipe. The latter generally comprises a filler head and a pipe body. It allows the fuel tank to be filled by means of a fuel dispensing nozzle that the user inserts into the inlet orifice of the filler pipe, which is located in the filler head.

Now, to meet stricter standards in terms of fire risks associated with an electrostatic discharge in an atmosphere containing air and an inflammable fuel, it is essential that the fuel systems provide a permanent conducting path between the fuel dispensing nozzle and the electrical earth of the motor vehicle throughout the entire filling phase in order to eliminate the electrostatic charges. For this purpose, the filler head is itself conducting.

The filler head generally comprises a bowl and a guide for the fuel dispensing nozzle (see for example patent application FR 05/02741 in the name of the Applicant). This guide consists in general of a part whose internal profile allows the nozzle to be optimally positioned during filling, the nozzle in general being inserted into the filling bowl. The filler head may for example be made of metal or a conductive plastic.

The electrical connection between the filler head and the electrical earth of the vehicle is in general performed at the present time by: ■ a tab made of conducting material, obtained by injection moulding or attached by welding to the head, generally when the earthing point on the chassis of the vehicle is located near the head; or

■ a "metal" earth wire (i.e. a copper core coated with an insulating sheath, equipped at each end with a crimped connector), generally when the electrical earth is further away from the head; the earth wire may for example be connected to the pipe body if the latter is conducting or may be connected directly to the chassis of the vehicle if the pipe body is insulating.

The "metal" earth wire has the disadvantage that the metal core may corrode and the wire has to be made from steels of the stainless type in order to avoid corrosion. Furthermore, the wire is fastened via its ends through crimped metal connectors. This means using additional components and involves more operations for fastening the earth wire. Also known are solutions for earthing the pipe by means of a metal wire which brings the filler head into contact with a conducting internal layer of the filler pipe, this internal layer itself being connected to the electrical earth. This type of solution can be applied only in the case of pipes whose wall comprises at least one internal conducting layer. This is for example the case of the invention described in application EP 0788915.

To alleviate these drawbacks, the desired aim of the present invention is to replace the "metal" earth wire with a conductive plastic wire that meets the same requirements and offers the following advantages: lower costs; no risk of corrosion; simpler fastening method; fewer materials to be recycled.

For this purpose, the subject of the invention is a filler pipe for a fuel tank, comprising: a filler head made of a conductive plastic; a pipe body, and further including an earth wire connecting the filler head to an electrical earth point of a vehicle, characterized in that the earth wire is also made of a conductive plastic.

The term "fuel tank" is understood to mean a sealed tank capable of storing fuel under diverse and varied usage and environmental conditions. An example of this tank is that with which motor vehicles are equipped. The fuel tank is preferably made of a plastic.

The term "plastic" is understood to mean any material comprising at least one synthetic resin polymer.

All types of plastics may be suitable. Particularly suitable are plastics that belong to the category of thermoplastics.

The term "thermoplastic" is understood to mean any thermoplastic polymer, including thermoplastic elastomers, and blends thereof. The term "polymer" is understood to mean both homopolymers and copolymers (especially binary or ternary copolymers). Examples of such copolymers are, non-limitingly, random copolymers, linear block and other block copolymers, and graft copolymers.

Any type of thermoplastic polymer or copolymer, the melting point of which is below the decomposition temperature, is suitable. Thermoplastics having a melting range spread over at least 10 degrees Celsius are particularly suitable. Examples of such materials include those that exhibit polydispersion in their molecular weight. In particular, polyolefins, thermoplastic polyesters, polyketones, polyamides and copolymers thereof may be used. A blend of polymers or copolymers may also be used, as well as a blend of polymeric materials with inorganic, organic and/or natural fillers such as, for example, but not limitingly: carbon, salts and other inorganic derivatives, natural or polymeric fibres. It is also possible to use multilayer structures consisting of stacked layers bonded together, comprising at least one of the polymers or copolymers described above.

One polymer often employed is polyethylene. Excellent results have been obtained with high-density polyethylene (HDPE). The wall of the tank may consist of a single layer of thermoplastic or of two layers. One or more possible additional layers may advantageously consist of layers made of a material that is a barrier to liquid and/or gases. Preferably, the nature and the thickness of the barrier layer are chosen so as to minimize the permeability of the liquids and gases in contact with the internal surface of the tank. Preferably, this layer is based on a barrier resin, that is to say a resin that is impermeable to the fuel, such as for example EVOH (a partially hydrolysed ethylene/vinyl acetate copolymer). Alternatively, the tank may be subjected to a surface treatment (fluorination or sulphonation) for the purpose of making it impermeable to the fuel. The tank according to the invention preferably includes an EVOH-based barrier layer located between the HDPE -based outer layers.

The term "earth wire" is understood to mean a wire obtained for example by extrusion, followed by a linear cutting operation in which the wire is cut to the desired length. According to the invention, the earth wire is made of a conductive plastic.

Preferably, the filler head and the earth wire are made of the same conductive plastic.

More preferably, the conductive plastic is conductive high-density polyethylene (HDPE), i.e. containing a conductive filler. Plastics that are also very suitable are polyamides and polyacetyls, and in particular conductive POM (polyoxymethylene).

In general, the electrical earth point is located on the pipe body (if this is conducting) or on the chassis of the vehicle.

In one particular embodiment, the filler head includes a housing, and one end of the earth wire is fastened to this housing. The housing may be produced during injection moulding of the filler head, for example in the form of an excrescence located on the head. The geometry of the housing is designed so as to introduce one end of the earth wire into the housing. For this purpose, the housing generally includes a hollow part, for example in the form of a cylinder, corresponding to the shape of the end of the earth wire. The earth wire is fastened inside said housing so as to establish an electrically conducting path.

Preferably, the other end of the earth wire is provided with a terminal lug designed to be fastened to the electrical earth point of the vehicle.

More preferably, the terminal lug is welded to the electrical earth point.

Also more preferably, the terminal lug is fastened to a fastening tab on the filler pipe.

In general, the terminal lug includes an orifice intended for passage of an earth screw, the function of which is to connect the terminal lug to the electrical earth of the vehicle. For this purpose, said orifice generally has dimensions approximately equivalent to those of an orifice made at the fastening point of the terminal lug in such a way that the two orifices are approximately aligned one with respect to the other. In this case, it is possible to pass the earth screw through both orifices.

The terminal lug generally is a part obtained by injection-moulding a conductive plastic. Furthermore, the terminal lug generally includes a housing intended for accommodating said end of the earth wire. The housing has an internal shape matched to the shape of said end, for example a substantially cylindrical shape.

Even more preferably, the two ends of the earth wire are connected by welding, to the housing on the filler head and to the housing for the terminal lug, respectively.

Ultrasonic welding has given good results.

The invention also makes it possible to fasten the earth wire to the filler head/pipe body assembly when the fuel system is being assembled, thus making it possible for the vehicle to be fitted with an equipped fuel system. When an earthing screw is inserted into the orifices provided for this purpose on the terminal lug and at the fastening point thereof, there is no rotation of the terminal lug, thereby preventing any deterioration of the wire.

Finally, by using a conductive plastic, it is easier to recycle the earth wire when the fuel system is being recycled. Figures 1 and 2 illustrate solutions of the prior art, while Figure 3 illustrates one particular embodiment of the invention, without restricting the scope thereof.

Figure 1 shows the assembly formed by a filler head (2) fastened to a pipe body (1). A metal earth wire (3) with an insulating sheath, one end of which is crimped into a female metal terminal lug (4), is fastened to the filler head (2) by means of a rivet (5). Such a solution has, as drawbacks, the large number of metal components for fastening the earth wire (3) (namely the terminal lug (4) and the rivet (5)) and a large size, necessary for the use of a tool for crimping the wire (3) onto the terminal lug (4).

Figure 2 illustrates the device for fastening the other end of the earth wire (3) to the pipe body (1). A clip (7) is assembled on a bracket (6), which is itself mounted on an external tab of the pipe body (1). The earth wire (3) is fastened to the bracket (6) by means of the clip (7). Such a solution has, as drawback, the specific geometry of the bracket (6), as the latter must be matched to the fastening tab on which the bracket (6) is mounted.

In Figure 3, a conductive plastic earth wire (3) is fastened via its ends to the filler head (2), by welding one end in a housing (8) made on the periphery of the head (2), and by welding the other end to an injection-moulded terminal lug (9) made of conductive plastic, respectively.

Such a solution has, as advantages, a fewer number of components for fastening the wire (3) and the fastening components are made of conductive plastic, which facilitates recycling.

Claims

C L A I M S

1. Filler pipe for a fuel tank, comprising: a filler head (2) made of a conductive plastic; a pipe body (1), and further including an earth wire (3) connecting the filler head to an electrical earth point of a vehicle, characterized in that the earth wire (3) is also made of a conductive plastic.

2. Pipe according to Claim 1, characterized in that the electrical earth point is located on the pipe body (1) or on the chassis of the vehicle.

3. Pipe according to either of Claims 1 and 2, characterized in that the filler head (2) and the earth wire (3) are made of the same conductive plastic.

4. Pipe according to Claim 3, characterized in that said conductive plastic is high-density polyethylene (HDPE) containing a conductive filler.

5. Pipe according to any one of Claims 1 to 4, characterized in that the filler head (2) includes a housing (8) and in that one end of the earth wire (3) is fastened to this housing (8).

6. Pipe according to Claim 5, characterized in that the other end of the earth wire (3) is provided with a terminal lug (9) made of conductive plastic and intended to be fastened to the electrical earth point.

7. Pipe according to Claim 6, characterized in that the two ends of the earth wire (3) are fastened by welding, to the housing (8) on the filler head and to the housing for the terminal lug (9), respectively.

8. Pipe according to either of Claims 6 and 7, characterized in that the terminal lug includes an orifice (10) intended for the passage of an earthing screw.