FIELD OF THE INVENTION The present invention is generally in the field of fluid tanks and accessories for fitting to such tanks. In particular, the invention is concerned with plastic fuel tanks and connection of fuel governing accessories thereto such as valves, fuel meters, etc.

BACKGROUND OF THE INVENTION A variety of valving means and other accessories are fitted onto fuel tanks, each having a different function. Typical examples of such accessories are valves of different types, fuel metering devices, etc. which are collectively referred to herein in the specification and claims as'fuel governing accessories". Fuel tanks with which the invention is concerned may be mobile, or stationary tanks, vehicle fuel tanks, etc.

The terms welding and weldable refer to any form of welding such as heat welding, ultrasonic welding etc, and may be interchangeably used herein.

It is common practice to connect fuel tank accessories to fuel tanks by performing an aperture of a size comfortably accommodating the accessories' housing, and fixedly attaching the accessory by various means, e. g. welding, heat welding, different fasteners, bayonet connections, etc. However, these arrangements have several drawbacks. In particular, in the case of heat welding, at

least the external surface of a fuel tank holding such one or more accessories should be made of or coated with a heat weldable material.

Another serious problem is concerned in particular with vehicle fuel tanks as it has now become an ever-growing requirement of environment concerned organizations and authorities that the rate of fuel permeation from the fuel tank and its associated accessories be minimal. The outcome of this requirement is that new connecting means are now required for ensuring substantially permeation-free connection between the fuel governing accessories and the fuel tank.

In accordance with a first aspect of the present invention there is provided a fuel tank which facilitates connection thereto of a fuel-governing accessory in a substantially permeation-free manner. In accordance with a second aspect of the present invention there is provided a seating member for use in manufacturing of such a fuel tank. A third aspect of the present invention is concerned with a method for connecting a fuel governing accessory to a fuel tank.

SUMMARY OF THE INVENTION In accordance with a first aspect of the present invention there is provided a multi-layer fuel tank which is substantially non-impermeable and comprising one or more openings each for accommodating a fuel governing accessory, the fuel tank characterized in that one or more of the openings are associated with an annular seating member made of a non-permeable material and having a peripheral portion fixedly embedded between layers of a wall of the fuel tank, and an exposed, inner portion encircling an opening for receiving the fuel governing accessory, at least said inner portion being made of or coated by a heat weldable material.

The fuel tank may comprise one or more layers of a non-permeable material or may be manufactured in a blow-molding process and than be fluorinated so as to impart it the non-permeation quality. A fuel tank, as referred to in the context of the present invention is any such tank which qualifies as non-penneable, regardless the method in which it has been manufactured or how it obtains its non-permeation quality.

The fuel tank with which the invention is concerned is made of a high-density laminated material typically comprising several layers including thin layers of a barrier material which are considered as non-permeable materials.

Alternatively, the tank undergoes a fluorination process so as to impart it non-permeability.

Preferably, the inner portion encircles the opening. However, by an alternative, only a portion of the seating member is exposed at an external surface thereof, for attaching thereto the fuel governing accessory.

The seating member is fitted in the fuel tank during an insert-molding process (or blow molding) wherein the seating member is introduced into a suitable mold during the molding process.

The fuel governing accessory is attached to the seating ring by heat welding or by ultrasonic welding. For the purpose of such welding it is required to leave some expansion space for molten material to flow during welding.

In accordance with a preferred design either or both an external surface of the inner portion of the seating member and a corresponding connecting portion of the fuel governing accessory are formed with an energy director having an annular shape and a tapering cross section. Typically, the energy director has a triangular cross section or a similar such cross section.

In order to prevent undesired disposition of the seating member within the fuel tank, in particular rotation thereof, and in order to increase the fixture of the seating member within the wall of the fuel tank, the peripheral portion of the seating member comprises a plurality of indentions or preferably openings wherein during the manufacture process of the fuel tank by insert-molding (blow molding), molten material (of the tank) flows into said indentions or openings resulting in fixture of the seating member within the fuel tank's well.

In order to reduce fuel permeation between adjoining surfaces of the seating member and the fuel tank, the peripheral portion of the seating member comprises on at least one face thereof at least one annular recess or rib. Preferably, two or more such recesses or ribs are provided in order to further improve the fuel

impermeability. The recesses or ribs prevent creeping of the elastomeric materials with respect to one another and their expansion, thereby reducing the fuel permeation therebetween. The recess and ribs also improve the connection between the wall of the tank and the seating member.

In accordance with one particular design, the seating member comprises an annular seat extending upwardly from the inner portion of the seating member for attaching thereto a corresponding portion of the fuel governing accessory.

In accordance with a second aspect of the present invention there is provided a seating member for fixedly accommodating a fuel governing accessory with an opening at a multi-layer non-permeable fuel tank, the seating member being substantially non-permeable and has an annular shape with a peripheral portion adapted for being fixedly embedded between layers of a wall of the fuel tank, and an inner portion encircling an opening for receiving the fuel governing accessory, where at least said inner portion is made of or coated by a heat weldable material for attaching thereto a corresponding portion of the fuel governing accessory.

A seating member in accordance with the second aspect of the present invention is typically introduced during the manufacture of a fuel tank which is made of a high-density laminated material during an insert-molding (blow molding) process.

Preferably, an external surface of the inner portion of the seating member is formed with an energy director having an annular shape and a tapering cross section.

Still preferably, the peripheral portion of the seating member comprises a plurality of indentations or openings for penetrating engagement with the fuel tank, so as to prevent undesired disposition therebetween.

In order to reduce fuel vapor permeation between the seating member and the accommodating fuel tank, the peripheral portion of the seating member is formed on at least one face thereof with at least one annular recess or rib.

Preferably, there are provided several such adjacent recesses or ribs which prevent creeping and expansion of the engaged materials.

In accordance with another aspect of the present invention there is proposed a method for connecting a fuel governing accessory to a multi-layer fuel tank being substantially non-permeable, the method comprising the following steps: (a) obtaining a non-permeable seating member having an annular shape with a peripheral portion, and an inner portion encircling an opening for receiving the fuel governing accessory, where at least said inner portion is made of or coated by a heat weldable material; (b) manufacturing a fuel tank of a substantially non-impermeable material, with the peripheral portion of the seating member fixedly embedded between layers of a wall of the fuel tank, with an opening in the tank exposing the inner portion of the seating member; and (c) introducing the fuel governing accessory into the opening and sealingly attaching the fuel governing accessory to the inner portion by heat welding or ultrasonic welding.

The fuel tank and the seating member for use in conjunction with the proposed method are described hereinabove and in detail hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the different aspects of the invention and to see how it may be carried out in practice, the invention will now be illustrated, by way of some non-limiting examples only, with reference to the accompanying drawings, in which: Fig. 1 is an isometric view of a fuel tank fitted with an inlet pipe and a valve attached thereto in accordance with the present invention; Fig. 2 is a sectional view along line II-II in Fig. 1, wherein the valve is schematically represented; Fig. 3 is a sectional view through half a seating member according to an embodiment of the present invention; Fig. 4A is an isometric view of a seating member in accordance with a preferred embodiment of the present invention;

Fig. 4B is a sectional view through a portion of a fuel tank and a seating member in accordance with Fig. 4A; Fig. 5 is a sectional view through still a different embodiment of a seating member in accordance with the present invention: and Fig. 6 is a sectional view through an embodiment in which only a portion of the seating member is exposed.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS Attention is first directed to Fig. 1 illustrating a fuel tank generally designated 10 having a top wall 11 fitted with a fuel inlet pipe 12 connected to the tank at 14 and a fuel valve 16 attached to the fuel tank at 18 as will hereinafter be explained in more detail with reference to Figs. 2 to 5. The fuel tank is made of high-density laminated material being essentially non-permeable and is produced at an molding process.

Fig. 2 is a sectional view along line II-II in Fig. 1 wherein wall 11 is integrally fitted during its manufacture process with a seating member generally designated 22 made of a non permeable material and having an annular shape and comprising a peripheral portion 24 fixedly embedded between corresponding layers 26 and 28 of the top wall 11, and an exposed, inner portion 32 formed with an aperture 34 for receiving valve 16. As can be seen, the inner portion 32 comprises an annular seating 36 which is welded to a corresponding skirt 38 of valve 16.

Welding the seating member may be by heat welding or ultrasonic welding, as known in the art.

It will be noted that in the present example the entire seating member 22 is made of a non-penneable material wherein its entire outer surface is made of a heat weldable material. However, in accordance with other embodiments, the seating member may be made of a different material wherein only the inner portion 32 is made or coated at least at its top surface with a heat weldable material. It will further be appreciated that the size of the exposed, inner portion 32 may be

significantly smaller and at the annular seating 36 may be omitted as will be noticed hereinafter.

Fig. 3 is a different embodiment of a seating member generally designated 40 wherein the peripheral portion 42 comprises a plurality of concentric annular ribs 44 the purpose of which being to reduce creeping process between the adjoining surfaces of the peripheral portion and the fuel tank receiving wall portion 11, thereby reducing to minimum the permeation of fuel vapor therebetween. However, instead of forming the annular ribs, there may be formed annular recesses having the same function and cooperating with the molded material of the tank. It will be appreciated, however, that the number and density of the annular recesses or ribs may vary depending on various parameters such as material of which the fuel tank and the seating member are made, sizes, type of fuel received within the fuel tank, etc.

Fig. 4A is an isometric view of a seating member 50 comprising a peripheral portion 52 and an inner portion 54 with a central opening 56 for receiving a valve member (not shown) as explained hereinabove.

As seen also in Fig. 4B, the peripheral portion 52 comprises a plurality of annular, concentric ribs 58 with intermitting openings 62. In the assembled position, the seating member 50 is embedded between layers 66 and 68 of the top wall 11 of the fuel tank, wherein during the blow-molding process the molded material of the fuel tank flows through openings 62 and between ribs 58 thereby fixing the seating member 50 and tightly mating the corresponding surfaces.

Fig. 5 is a sectional view through a specific embodiment of a seating member 70 in accordance with a preferred embodiment of the invention comprising a peripheral portion 72 formed with a plurality of openings 74 and annular concentric ribs 75, and an inner portion 76 encircling an opening 78 for receiving a fuel tank accessory (not shown) as explained hereinbefore. It is noted that the inner portion 76 is somewhat thicker than the peripheral portion 72 and comprises an energy director 82 which is an annular triangle upwardly extending. Upon placing a corresponding welding surface of a fuel tank accessory (not shown) such as, for

example, a fuel valve, and applying heat or ultrasonic waves, the energy director 82 deforms (in fact melts) and sealingly welds to a corresponding connection portion of the accessory.

Fig. 6 is a sectional view through a different embodiment of the invention wherein the seating member generally designated 90 has a peripheral portion 92 received within a wall portion 94 of a fuel tank as explained hereinbefore wherein an inner portion 96 of the seating member is exposed only at a top surface thereof 98 with a bottom surface thereof and a most inner portion thereof being enveloped by an extension 102 of the tank The extension 102 is fitted at a top face thereof 104 with a sealing O-ring 106 for sealing engagement with a corresponding wall portion of the fuel governing accessory 110 which as explained hereinbefore is heat welded at 112 to the exposed surface 98 of the sealing member 90.

Whilst preferred embodiments have been shown and described, it is to be understood that it is not intended thereby to limit the disclosure, but rather it is intended to cover all modifications and arrangements falling within the spirit and the scope of the invention, as defined in the specification and claims, mutatis mutandis.

For example, the seating member and the corresponding flanging portions of the fuel tank may acquire other shapes and various combinations of fixing the recesses, ribs and openings may be performed. Furthermore, the inner portion of the seating member may be formed in a variety of different shapes depending among others, on the shape of a corresponding connecting portion of the fuel vale accessory to be attached thereto.