Method for fastening a component inside a fuel tank

The invention relates to a method for fastening a component inside a fuel tank. It relates more especially to a method for fastening components in a zone distant from the mounting plate that seals the service opening, and this being in an easy and reliable manner. It is especially advantageous for fastening the pump/gauge module inside multi-compartment tanks.

In heat engine vehicles, in particular in motor vehicles, the fuel system includes at the present time, apart from the tank for storing the fuel, a number of accessories. Among these accessories are, inter alia, valves, filters, pumps, gauges and pressure regulators, which are accessories inside the tank. The current tendency is to integrate several of these components into a single module which is fastened inside the fuel tank (FT), generally by insertion through an opening provided for this purpose (and normally (during operation) sealed by a mounting plate) and then, by fastening with the aid of suitable means, which are preferably reversible so that said module can be removed for maintenance, repair, etc.

Thus, Patent US 5,931,353 in the name of the Applicant describes a tank provided with reliefs (slides) moulded as one part with the wall of the tank and into which the module can be inserted and held owing to complementary reliefs provided on its lateral surface (flexible protuberances). However, the geometry of these reliefs is such that if the relative bulkiness of the module with respect to the cavity into which it must be inserted is large and/or if the fastening location is distant from the insertion opening, the module cannot in fact be fastened in practice. Moreover, such a fastening system is too readily reversible so that the pump may in fact be detached during handling of the tanks and/or when they are fastened to a vehicle.

Patent US 4,716,931 proposes a fastening system for an FT pump/gauge that makes it possible to solve the problem of remote fastening owing to the use of a support which is fastened to a relief close to the insertion opening and into which the pump/gauge is inserted. However, with such a system, not all the movements of the pump/gauge are stopped since, on the one hand, the end of the support where the pump/gauge is fastened is free and since, on the other hand, this component is simply inserted into a relief (ring) of the support and is not fastened to it.

Patent US 5,040,516 proposes a system for fastening components inside multi-compartment tanks (or saddle-shaped tanks, "saddle tanks" in the jargon of the field) which also uses a support fastened close to the insertion opening. This support comprises hollow reliefs into which arms serving as an extension to the accessories are inserted. Such a system also does not make it possible to stop all the movements of the components since the end of the arms where the components are fastened is free.

The object of the present invention is hence to provide a method that makes it possible to fasten (preferably in a detachable manner, i.e. with reversible fastening means (that can be locked/released)) a component to the lower internal wall of an FT at a location distant from the insertion opening, and this in both an easy and reliable manner, i.e. it makes it possible to flatten the component against the bottom of the tank and to hold it in the location where it must be fastened and in the correct angular position. This method consists in providing the tank with a fastening point close to the insertion opening and with relief(s) at the location where the component must be fastened inside the tank, in inserting the component inside the tank via the opening and in positioning it on the lower wall of the tank with the aid of the relief ; and finally : in mechanically connecting the fastening point and the component with the aid of a support.

In the context of the invention, the term "fuel" is understood to mean a hydrocarbon suitable for supplying (internal combustion) heat engines. The FT to which the invention applies is suitable either for heat engines supplied with volatile liquid fuels or for engines supplied with heavy liquid fuels (diesel). It is generally intended to be incorporated into a motor vehicle (car, lorry, motorcycle, river boat, ocean-going vessel or aeroplane for example). It may have any shape, even a complicated, for example multi-compartment or saddle, shape (which is often the case in practice considering the presence of other objects in its vicinity on the vehicle). According to the invention, this tank is based on a material that is compatible with each of the liquid hydrocarbons that it is capable of handling. This material must be chemically inert both with respect to volatile liquid hydrocarbons (petrol) and heavy liquid hydrocarbons (diesel) at the customary operating pressures and temperatures. It may be a plastic or a metal. Thermoplastics give good results within the context of the invention, especially due to the advantages of weight, mechanical strength and chemical

resistance and easier processing (which justifiably makes it possible to obtain complex shapes).

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 copolymers, 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. Synthetic 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, it is possible to use polyolefϊns, polyvinyl halides, thermoplastic polyesters, polyketones, polyamides and copolymers thereof. A blend of polymers or copolymers may also be used ; similarly it is also possible to use a blend of polymeric materials with inorganic, organic and/or natural fillers such as, for example but non-limitingly : carbon, salts and other inorganic derivatives, natural fibres, glass fibres and polymeric fibres. It is also possible to use multilayer structures composed of stacked and joined layers comprising at least one of the polymers or copolymers described above.

Polyvinyl halides and polyolefms are generally preferred. One polymer often employed is polyethylene. Excellent results have been obtained with high-density polyethylene (HDPE). In a known manner, the impermeability of this plastic to volatile hydrocarbons may be improved by surface treatment (fluorination, sulphonation, etc.) and/or by the use of a barrier layer (for example based on polyamide (PA) or on a polyvinyl alcohol [homopolymer (PVOH) or ethylene/vinyl alcohol copolymer (EVOH)].

Preferably, the tank is a multilayer structure that includes at least one layer based on HDPE and at least one layer based on EVOH (the expression "based on" meaning "mainly composed of, it being understood that these layers may comprise other polymers and/or additives in a minor amount (by weight)). The component to which the method according to the invention applies may also comprise at least one part made of plastic (HDPE).

The component to be fastened inside the FT according to the invention may be any component generally intended for supplying the engine with fuel, for monitoring the fuel level in the tank, for ventilating the tank, etc. The present

invention applies most particularly well to the fuel filter and in particular to a filter housing that includes the fuel filter. The invention applies also most particularly well to the pump and in particular to a module that includes, besides the pump, at least one component chosen from a fuel filter, a gauge, and a pressure regulator (that makes it possible to supply the engine with fuel at a desired pressure). It should be noted that this module may also incorporate other accessories such as gates and valves (for example a non-return valve and/or a valve for preventing overfilling). Most particularly preferably, such a module includes what is known as a swirl pot in which the pump is held and draws fuel in order to supply an engine therewith.

According to the invention, the tank comprises an opening through which certain components may be inserted and which is generally (i.e. by default, when the tank is in service) sealed (i.e. closed in a leaktight manner) and this generally being with the aid of a mounting plate (type of substantially flat cover) which may or may not bear certain accessories (valves, electrical or fluid connections to the outside, etc.). This opening may have been produced at the same time as the tank was manufactured (which generally takes place by blow moulding or thermo forming in a mould) or have been machined subsequently in the wall of this tank. According to the invention, the tank is provided with a fastening point close to the insertion opening, i.e. at a distance that allows an easy manual or automated fastening of an object. This point may simply consist of one portion of the wall that is free/available for fastening by welding, bonding, mechanical fastening (rivets, bolts, etc.) and which may or may not be in relief with the neighbouring wall. Alternatively and preferably, it may be a specific object (type of fastening connection) which is attached to this wall (e.g. by welding, bonding, etc.). This object may have any shape ; it is preferably substantially flat and/or circular. A fastening ring or disc welded to the internal wall of the tank gives good results. This object may also consist of a base and a fixation element attached to or in one piece with the base. Preferably, this part is provided with relief(s) that enable a rapid and detachable fastening of a part provided with complementary relief(s) which is attached to or as a single piece with the support serving as the rigid fastening. In a particular embodiment, the object may be a spin clip comprising a base and a fixation clip. In this embodiment, the relief(s) is represented by the fixation clip that is aimed to cooperate with a complementary clip on the support.

The fastening point described above is by definition located on the wall of the

tank, generally on its internal wall. In particular, when the tank is a saddle tank comprising at least two compartments and a reduced volume that connects these compartments, this point is preferably located in this volume and in particular, on its lower wall. Indeed, in such a tank, the service opening is generally in the vicinity of or even in this volume also.

When the component is a "pump" module, it may be advantageous to fasten it inside a compartment of the tank, the shape and capacity of which are such that said compartment acts as a (main or auxiliary) swirl pot for the pump. The moulding of a swirl pot as a single piece with the wall of the tank is described in Application WO 2007/026011 in the name of the Applicant, the content of which is, for this purpose, incorporated by reference in the present application. It should be noted that this variant is also advantageous independently of the present invention, whatever the method of fastening the pump.

By definition, the relief(s) (used in the singular later on for simplicity) make(s) it possible to place the component at the desired location on the lower wall of the tank and in the desired angular position. It therefore makes it possible to hold the component in place on the bottom of the tank in order to facilitate the assembly operations. Conversely, it does not generally make it possible to prevent the vertical movements thereof so that the insertion and removal of the component into/from this relief are particularly easy. Protuberances (preferably at least two in number) of substantially conical shape, moulded in the tank and complementary to hollow reliefs that are also conical present in the component (or at least : its outer envelope) are particularly suitable for ensuring correct positioning of said component. In this case, the positioning takes place up to a stop and a portion of the movement for positioning over these reliefs may consist of a sliding over the lower wall of the tank. This variant with conical reliefs is also advantageous since it makes it possible to prevent the rotation of the arm around the fastening point (movement which may be induced following deformation of the location where the fastening point is ; this phenomenon is illustrated in Figure 4.3 appended to the present application).

When the tank is made of plastic, it is generally obtained by moulding in a mould. Hence, advantageously, either the relief described above is moulded as a single piece with the wall of the tank (for example, by using moveable parts in the mould as described in the aforementioned Patent US 5,931,353 in the name of the Applicant, the content of which is, for this purpose, incorporated by reference in the present application), or it consists of a specific part that is fastened to the wall of the

tank at the same time that the tank is manufactured. The same observation in fact applies to the fastening point. The first alternative is preferred for the relief, whilst the second is preferred for the fastening point.

According to one preferred variant of the invention, the tank is moulded from an extruded cylindrical parison, cut into two sheets that are moulded and assembled in a mould comprising cavities and a core, said process comprising the following steps :

1. the parison is introduced into the mould cavities ;

2. the core is introduced inside the parison ; 3. the mould is closed so that the cavities come into leaktight contact with the core ;

4. the parison is pressed against the cavities by blowing through the core and/or applying a vacuum behind the cavities ;

5. the fastening point and/or the relief(s) are fastened to or moulded into the parison ; 6. the mould is opened to withdraw the core ;

7. the final moulding of the parison is carried out by blow moulding (by injecting a pressurized fluid inside the parison) and/or thermoforming (by applying a vacuum behind the cavities).

Such a process is described in Application WO 2007/000454 also in the name of the Applicant, the content of which is, for this purpose, also incorporated by reference in the present application.

According to the invention, a mechanical connection is created between the fastening point and the component with the aid of a support. This is understood to mean that use is made of a specific part, generally of elongated shape (the length of which is sufficient to connect the fastening point and the component, which may be positioned at locations at least a few centimetres, or even tens of centimetres apart in the tank, which is often the case in practice and in particular with saddle tanks) to limit the relative movements of the component with respect to the fastening point. This is therefore a type of rigid arm which is either attached to (or even is one piece with) the component, or is a separate part, one end of which is (preferably detachably) fastened to the component once this component is stopped by the relief(s). The second variant is preferred. Likewise, the "free" end of this arm (once it is) attached to the component is preferably also detachably fastened to the fastening point. According to one advantageous variant of the invention, at least one flexible portion (preferably, a spring) is integrated into the support and/or located between

the support and the component. Its purpose is to press the component against the bottom of the tank whatever the case in question (taking into account manufacturing tolerances, deformation of the FT, etc.). Preferably, it is a spring that is relatively short and/or that has a high return force so as to ensure correct fastening of the component.

One detachable fastening means that is particularly suitable within the context of the invention consists in providing the support with clips that can be inserted into or grip corresponding reliefs on the fastening point and/or on the component. Alternatively to or in addition to these clips, the support and respectively the fastening point and/or the component may comprise complementary reliefs

(protuberances and hollows respectively) that generally make it possible to insert a portion of one part inside another part.

The aforementioned fastening(s) may be carried out manually by an operator, but preferably they are performed by a robot. The present invention is illustrated, in a non- limiting manner, by Figures 1 to

6, which constitute schematic diagrams of certain preferred variants of the invention.

Thus, Figure 1 shows, separately, 3 parts intended to be mechanically connected and that are constituted by a fastening ring, a fastening arm and a pot intended to receive a pump/gauge module. Figure 2 shows these 3 parts connected together and fastened inside an FT. Figure 3 illustrates, in detail (via 3 views), a way in which the 3 parts can be connected. Figure 4 schematically illustrates the positioning reliefs respectively on the wall of the tank and on the pot, which are not visible in the other figures. Figure 5 illustrates how to make the fastening between the pot and the tank flexible. Finally, Figure 6 illustrates, via 4 views, a filter housing with a fastening arm.

Figure 1.1 shows a fastening ring (1) intended to be fastened (preferably by welding) to the internal wall of a saddle tank, this being in a reduced volume that connects the compartments of this saddle tank (see Figure 2). This "welded" ring (1) comprises protuberances (2) and cavities (3) intended to cooperate respectively with hollows (5) and clips (6) of the fastening arm (4) illustrated in Figure 1.2. This arm (4) also comprises clips (8) intended to grip a corresponding relief (10) on a pot (9) of a pump illustrated in Figure 1.3, and also reliefs (7, T) intended to cooperate with corresponding reliefs (11, 10) on the pot (9). Figure 2 shows how this pot (9), comprising a pump (9'), is fastened inside a saddle FT (12) with the aid of the arm (4) and the ring (1), the latter being welded to

the lower wall of the tank (12) in a portion of it that connects 2 of its compartments (for which only a truncated view of the compartment containing the pump (9') is illustrated).

In Figure 3, it is possible to see in greater detail how the various reliefs described above in support of the preceding figures cooperate when the arm (4) fastens the pot (9) inside the tank (12).

Figure 4 schematically illustrates how conical reliefs (13) moulded as a single piece with the wall of the tank cooperate with corresponding reliefs or conical hollows (14) present in the lower portion of the pot (9), one view of which is illustrated in Figure 4.2. The purpose of these conical reliefs is not only to position the module before it is fastened but also to prevent the rotation of the arm around the fastening point, which movement may be induced following deformation of the location where the fastening point is found, as illustrated in Figure 4.3.

The fastening of the assembly illustrated in Figure 2 took place as follows : - the pot (9) equipped with the pump (9') is inserted into the tank via an opening (not represented) and it is positioned on the wall with the aid of reliefs (13, 14) as illustrated in Figure 4 ;

- the arm (4) is inserted through the same opening and is fastened first to the pot (9) with the aid of clips (8) and reliefs (7, T) which respectively grip the reliefs (10) and are inserted into the reliefs (10, 11) as illustrated in Figure 3 ;

- finally, the other end of the arm is fastened to the ring (1) which has been pre- welded to the wall of the tank, this fastening being via the clips (6) and the reliefs 5 which respectively cooperate with the reliefs (2) and (3) of the ring (1) (as illustrated in Figure 3 also). Figure 5 schematically shows how the fastening between the arm (4) and the pot (9) may be made flexible : it suffices to insert a spring (15) between the arm (4) and the pot (9), this spring (15) being compressed and exerting a force on the pot (9) in the direction of the arrow (16), which therefore presses the pot against the wall of the tank (12). Figure 6 shows a filter housing (17) for supporting a filter (20) and comprising a fastening arm (4) in one piece with the filter housing (17).

In particular, Figure 6.1 illustrates a global view representing the assembly filter housing (17)/fϊlter(20)/fastening arm (4), a pump (9'), a level gauge (21) and other pipes. The fastening arm (4) comprises, at one extremity opposite to the filter housing (17), a fixation element (19) in the form of a hollow cylinder. The fixation

element (19) is aimed to cooperate with a fastening point that consists of a spin clip (18) that is intended to be fastened (preferably by welding) to the internal wall of a saddle tank. The spin clip (18) comprises a base (18') and a fixation clip (18") that is substantially orthogonal to the base (18') and cooperates with the fixation element (19) (as visible on Figure 6.3 (a top view of the assembly filter housing/filter/spin clip)).

The fastening of the assembly illustrated in Figure 6 took place as follows : - the filter housing (18) equipped with the filter (20) is inserted into the tank via an opening (not represented) ; - the fixation element (19) is fastened to the fixation clip (18") of the spin clip (18) (which has been pre-welded to the wall of the tank) by inserting the fixation clip (18") inside the fixation element (19) and by rotating the fixation element (19) (and the filter housing (17) attached to it via the arm (4)) in such a manner as the fixation element (19) cooperates with the fixation clip (18") ; - finally, the filter housing (17) is positioned on the wall with the aid of reliefs (not illustrated).