Patent Application
20080164255
The present invention relates to a conducting system for a filling pipe.
Motor vehicle fuel systems usually comprise a fuel tank and a filling pipe. The filling pipe enables the fuel tank to be filled from a fuel nozzle which the user inserts into the entrance orifice of the filling pipe (the filling head, as it is also called).
In the case of tanks having a plastic pipe, it is known practice to make the plastic at least partly conducting and/or to remove electrostatic charges to the vehicle chassis in order to prevent electrostatic charges building up on its surface, with all the associated risks. For this purpose there is usually at least one metal part in contact (direct or indirect) with the plastic on the one hand, and with the vehicle chassis on the other hand.
In this way, a plastic pipe head is usually provided with a system comprising a metal bowl force-fitted into the filling pipe and a metal head fitted onto the pipe head whose function is to establish a contact with the vehicle chassis. The system also includes a guide for the filling nozzle; this guide is usually made in one piece which is inserted into the filling bowl, its inner profile assisting in positioning the nozzle during the filling operation. This part may be made of plastic or metal.
Where the pipe head is provided with the said system, the metal bowl is usually positioned by means of orientating features on the pipe head.
In certain prior-art designs, the bowl comprises teeth that make axial contact with the metal head when the latter is crimped around the outside of the pipe head. An O-ring is placed between the metal head and the plastic filling pipe to provide a peripheral seal between the filling pipe and the metal head.
A conducting path for static electricity generated during the filling operation is thus established between the nozzle, the nozzle guide, the filling bowl, the teeth of the bowl, the metal head and, via a metal lug fixed to the metal head, the vehicle chassis.
One problem with this system is that if there are moulding defects in the pipe, at least one of the teeth of the bowl may not be in contact with the metal head once the bowl is fitted. Static electricity that may build up on the surface of the filling bowl will not then be carried away efficiently into the vehicle chassis because the conducting path is no longer continuous. Another problem with this design is that the bowl is metallic (whereas plastics are lighter and easier to form into complex shapes).
To alleviate these problems and to simplify the fitting of the bowl to the pipe head, the subject of the invention is a conducting system for a fuel tank filling pipe, comprising
According to the invention, the bowl and the nozzle guide (the function of which was described above) are inserted into the metal head; that is to say, they are in fact crimped into the said head with the aid of the teeth, or, in other words, the metal head is engaged on these parts.
According to the invention, therefore, the bowl is provided around its periphery with deformable teeth which, when the bowl and the guide are inserted into the metal head, deform to give permanent radial contact with the metal head, even if there are moulding defects in for example the pipe head. Any static electricity generated by fuel being poured in through the filling nozzle can thus be carried away into the bodywork of the vehicle via the filling bowl, the teeth, and the metal head, this last being connected directly to the chassis of the vehicle.
According to the invention, the guide is in direct contact with the bowl—that is, it is either mounted in or on the bowl, or made in one piece with the bowl. In the system according to the invention, the filling bowl and the guide for the filling nozzle preferably form a one-piece unit.
The term “plastic” is used to denote any material comprising at least one synthetic resin polymer.
All types of plastic may be suitable. Very suitable plastics belong to the category of thermoplastics.
The term “thermoplastic” denotes any thermoplastic polymer, including thermoplastic elastomers, and their blends. The term “polymer” denotes both homopolymers and copolymers (especially binary or ternary copolymers). Without implying any limitation, examples of such copolymers are: random copolymers, linear block copolymers, other block copolymers and graft copolymers.
Any type of thermoplastic polymer or copolymer whose melting point is below the decomposition temperature is suitable. Synthetic thermoplastics that have 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 may a blend of polymeric materials with inorganic, organic and/or natural fillers such as the following non-exhaustive list: carbon, salts and other inorganic derivatives, and 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.
More preferably, the plastic of the bowl/guide unit is conducting high-density polyethylene (HDPE) (that is to say, it comprises a conducting filler—such as carbon black or carbon fibres - and/or a conducting coating). This part or these parts (depending on whether or not they are formed in one piece) are preferably produced by injection moulding (which makes it possible to overmould them onto one or more inserts, such as a reinforcing ring for example: see later).
According to the invention, the bowl/guide unit is force-fitted into the filling pipe. Movement of the unit relative to the pipe (axially and in rotation) is preferably prevented by an appropriate design. For example, it is advantageous to provide depressions or recesses (stamped portions) in the pipe to correspond to the teeth, in such a way that it can support axially and prevent rotation of the bowl/guide unit in the pipe because of the teeth and stamped portions acting together. In this variant, the teeth therefore have a dual function of conductivity (removal of charges) and attachment.
The teeth are preferably flat (meaning that they are thin and of elongate shape as illustrated in the figures attached to this application). These teeth preferably give the bowl/guide unit a diameter greater than that of the opening in the metal head designed to house it. What this means is that their size is such that they are compressed by the head during assembly, thus ensuring permanence of the contact whatever the quality of the moulding of the parts (distortion, tolerances, etc.). It is advantageous to provide the system according to the invention with a seal (such as an O-ring) to seal the assembly. This seal is preferably situated on the filling pipe in a position such that it is compressed by the metal head once the system is assembled. A groove may be provided on the pipe to house and locate the seal.
In a preferred variant of the invention, a metal annulus is present on the periphery of the bowl/guide unit, so that when the unit is installed, the annulus gives sufficient rigid support to prevent the filling pipe from deforming with the effect of age, and, by the same token, to prevent the seal deteriorating. This annulus can be crimped onto the bowl, but the bowl is preferably overmoulded onto it (to eliminate an assembly step). Most particular preference is given to overmoulding a bowl/guide unit onto it in one piece. The present invention also relates to a process for producing (assembling) a conducting system as described above. This process comprises the following steps
Without limiting the scope of the invention,
| Number | Date | Country | Kind |
|---|---|---|---|
| 05.02741 | Mar 2005 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2006/060805 | 3/16/2006 | WO | 00 | 3/13/2008 |
