TECHNICAL FIELD

The present disclosure relates to a fuel tank apparatus and method. In particular, but not exclusively, aspects of the invention relate to a fuel tank assembly; to a vehicle; and to a method of forming a fuel tank assembly.

BACKGROUND

A fuel tank is provided in a vehicle to store fuel, such as gasoline or diesel fuel, for an internal combustion engine. In use, the pressure in the fuel tank may change, for example due to changes in the ambient temperature, cycling between high and low pressures. In order to maintain the shape of the fuel tank, it is common for fuel tanks to be vented to atmosphere. However, vapours may be vented from the fuel tank causing increased emissions. In order to reduce these emissions, the fuel tank may be a closed system and the fuel tank at least substantially sealed. For example, a PHEV (Plug-in Hybrid Electric Vehicle) may incorporate a fuel tank which is a closed system. A standard blow-moulded plastic tank, for example having a wall thickness of approximately 5.5mm, would undergo deformation of up to 10mm as the internal pressure cycles between high and low pressures. The repeated deformation of the fuel tank may cause fatigue which could potentially result in damage to the fuel tank and the surrounding body of the vehicle. It is known to reinforce the fuel tank to inhibit deformation, typically by adding complicated baffles or webs inside the tank, and/or to form contours or ribs in the outer walls of the tank, so as to resist flexing of the tank walls, but these often reduce the usable volume for storing fuel and may increase the complexity and/or cost of the fuel tank.

At least in certain embodiments, the present invention seeks to overcome or ameliorate disadvantages associated with known arrangements.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a fuel tank assembly, to a vehicle and to a method of forming a vessel as claimed in the appended claims.

According to a further aspect of the present invention there is provided a fuel tank assembly for a vehicle, the fuel tank assembly comprising:

a vessel for storing fuel, the vessel having at least one wall moulded from a plastics material; and a member comprising a stiffening member fully encapsulated in the plastics material forming the at least one wall of said vessel to stiffen that at least one wall. According to a another aspect of the present invention there is provided a fuel tank assembly for a vehicle, the fuel tank assembly comprising: a vessel for storing fuel, the vessel having at least one wall moulded from a plastics material; and a member comprising a reinforcing member fully encapsulated in the plastics material forming the at least one wall of said vessel to reinforce that at least one wall.

The plastics material may be over-moulded onto the reinforcing or stiffening member. The reinforcing or stiffening member may provide localised reinforcement or stiffening of the vessel, for example in an associated wall of the vessel. At least in certain embodiments, the fuel tank assembly may be sealed to reduce or prevent evaporation of fuel. In use, changes in the pressure in the vessel may cause the vessel to expand or contract. By providing said reinforcing or stiffening member, the fuel tank assembly can accommodate these pressure changes with negligible dimensional changes. By encapsulating the reinforcing or stiffening member into the plastics material, the reinforcing or stiffening member may be integrated into the vessel. The reinforcing or stiffening member may be encapsulated in a substantially continuous section of said at least one wall, i.e. in a section of the at least one wall which does not include apertures or through-holes. The at least one wall in which the reinforcing or stiffening member is encapsulated may be a substantially continuous wall. By encapsulating said reinforcing member, the plastics material may form a substantially continuous inner surface and a substantially continuous outer surface of the at least one wall of the vessel.

The full encapsulation of the reinforcing or stiffening member into the wall may maximise the additional strength provided to the fuel tank by the member, and also protect the member from environmental damage such as corrosion (in the case of metal) or mechanical damage. In particular, the choice of material to be used for the member can be wider, because the material may be chosen without having regard to these factors, enabling the choice to be focused on materials which are low cost and/or high performance in terms of reinforcement and stiffening. It will be understood that full encapsulation may be understood to mean that the member is completely encased within the material of the wall, such that no part (or substantially no part) of the member is exposed through the wall, both from the inside and from the outside of the vessel.

The reinforcing or stiffening member may be inserted into a mould and the vessel then moulded such that the plastics material may encapsulate the reinforcing member. The reinforcing or stiffening member may thereby be integrated into the structure of the vessel during moulding of the vessel. The reinforcing or stiffening member may thereby be moulded into and held securely within the structure of the vessel. At least in certain embodiments, this may give additional strength and/or rigidity to the fuel tank reducing or negating the need for internal reinforcement or bracing of the fuel tank. The reinforcing or stiffening member may thereby reinforce or stiffen the fuel tank with little or no reduction in the volume available for storing fuel.

The reinforcing or stiffening member may comprise an aperture. The aperture may comprise a through-hole in said reinforcing or stiffening member. The aperture may be filled with the plastics material from which the vessel is moulded. The reinforcing or stiffening member may comprise a plurality of apertures forming a mesh structure in the member, the mesh structure being encapsulated in said plastics material. During moulding of the vessel, the plastics material may flow into and fill said apertures while in a molten state. The plastics material may subsequently solidify in said apertures, thereby integrating said one or more reinforcing or stiffening member into the vessel. The reinforcing or stiffening member may comprise a plurality of interconnected members arranged to form said mesh structure. The mesh structure may be encapsulated in said plastics material. During moulding of the vessel, the plastics material may flow through said apertures and encapsulate said interconnected members. The reinforcing or stiffening member may be fully encapsulated in the plastics material forming the at least one wall. In this arrangement, the plastics material may extend over both sides of the reinforcing or stiffening member, thereby forming an inner surface and an outer surface of the at least one wall of the vessel. The reinforcing or stiffening member may be contained within the plastics material. In certain embodiments, the plastics material may define both the inner and outer surfaces of the at least one wall. The reinforcing or stiffening member may be deformable to match the profile of the vessel during the moulding process. Alternatively, or in addition, the reinforcing or stiffening member may have a profile which at least substantially matches a profile of the corresponding portion of said vessel. The reinforcing or stiffening member may be pre-formed so as to match the profile of said vessel.

Alternatively, the reinforcing or stiffening member may be rigid or inflexible. The reinforcing or stiffening member may thereby at least partially inhibit deformation of that section or wall of the vessel. For example, deformation of an upper wall and/or a lower wall may be substantially prevented in use.

The at least one wall may comprise an upper wall. The reinforcing or stiffening member may comprise an upper reinforcing or stiffening member encapsulated in the upper wall. The at least one wall may comprise a lower wall. The reinforcing or stiffening member may comprise a lower reinforcing or stiffening member encapsulated in the lower wall. The at least one wall may comprise a sidewall. The reinforcing or stiffening member may comprise a sidewall reinforcing member encapsulated in said sidewall. The sidewall reinforcing or stiffening member may be formed as a separate component. Alternatively, the sidewall reinforcing or stiffening member may be formed integrally with the upper reinforcing or stiffening member and/or the lower reinforcing or stiffening member.

The reinforcing or stiffening member may be made of metal. The apertures may, for example, be formed in said sheet metal by a punching, stamping or cutting operation. Alternatively, the reinforcing or stiffening members may comprise a woven mesh, for example a woven wire mesh. The reinforcing or stiffening members may be formed from other materials, such as a plastics material. The reinforcing or stiffening members may comprise a mesh structure which is moulded from a plastics material, such as polyester or nylon. In a variant, the mesh could be woven from filaments, for example synthetic or carbon fibres. The stiffening or reinforcing member may be arranged to extend substantially across the wall in which the member is encapsulated. In this way, the stiffness of the wall in which the member is encapsulated, is greatly increased, and deformation caused by pressure variation in the vessel is substantially prevented without significantly reducing the volume of the vessel.

The fuel tank assembly may be sealed. The fuel tank assembly may be a closed system.

According to a further aspect of the present invention there is provided a vehicle comprising a fuel tank assembly as described herein. The vehicle may be a hybrid electric vehicle (HEV) comprising an internal combustion engine and one or more electric traction motor. The vehicle may, for example, be a plug-in hybrid electric vehicle (PHEV)

According to a further aspect of the present invention there is provided a method of forming a vessel, the method comprising: inserting a stiffening or reinforcing member into a mould; introducing a plastics material into the mould; and displacing the plastics material against said mould to form at least one wall of the vessel; wherein the stiffening or reinforcing member is encapsulated in the plastics material forming said at least one wall of the vessel. The plastics material may be over-moulded onto said stiffening or reinforcing member. The stiffening or reinforcing member may thereby be integrated into the at least one wall of the vessel.

The stiffening or reinforcing member may comprise an aperture. The aperture may comprise a through-hole extending through said stiffening or reinforcing member. The plastics material may fill said aperture when the vessel is formed. The plastics material may be displaced through said aperture when the vessel is formed.

The stiffening or reinforcing member may comprise a mesh structure. The mesh structure may be encapsulated in said plastics material when the at least one wall of the vessel is formed.

The stiffening or reinforcing member may be pre-formed. The stiffening or reinforcing member may at least substantially match an internal profile of an associated portion of said mould.

The method may comprise supporting the stiffening or reinforcing member in said mould at or proximal to an inner surface of the mould. The stiffening or reinforcing member may be positioned against the inner surface of the mould.

The stiffening or reinforcing member may comprise one or more of the following: an upper stiffening or reinforcing member for stiffening or reinforcing an upper wall of the vessel; a lower stiffening or reinforcing member for stiffening or reinforcing a lower wall of the vessel; and a sidewall stiffening or reinforcing member for stiffening or reinforcing a sidewall of the vessel.

The plastics material is introduced into the mould in a molten state. For example, the plastics material may be dropped into the mould from above. The plastics material may be introduced into the mould as a parison. Alternatively, the plastics material may be introduced into the mould as one or more sheets of plastics material.

The method may comprise introducing a compressed gas to displace the plastics material against the mould. The compressed gas may, for example, be introduced into an interior of a parison of plastics material. The parison may be sealed top and bottom, for example when the mould is closed. The introduction of the compressed gas displaces the plastics material against the mould. The stiffening or reinforcing member may be disposed in said mould between the plastics material and an internal wall of the mould. When the plastics material is displaced against the mould, for example by introduction of a compressed gas, the plastics material is forced over and around the stiffening or reinforcing member. The plastics material takes the shape of the mould and the stiffening or reinforcing member is encapsulated therein. This can be achieved with the material on the outer side of the tool during conventional blow moulding process, or inside and/or outside during a twin sheet Next Generation Fuel System (NGFS) blow moulding process. The vessel may be a component of a fuel tank assembly for a vehicle. The fuel tank assembly may be adapted for storing a fuel such as a gasoline or diesel fuel. It will be understood that the composition of the plastics material may vary depending on the type of fuel to be stored therein. Other fuel tank fittings may be fastened during moulding of the vessel. For example, an encapsulated ring may be encapsulated in said vessel. The encapsulated ring may provide a mount for a fuel supply system.

According to a further aspect of the present invention there is provided a fuel tank assembly for a vehicle, the fuel tank assembly comprising a vessel for storing fuel, the vessel having at least one wall moulded from a plastics material; and a member comprising a stiffening member at least partially encapsulated in the plastics material forming the at least one wall of said vessel to stiffen that at least one wall.

According to another aspect of the present invention there is provided a fuel tank assembly for a vehicle, the fuel tank assembly comprising: a vessel for storing fuel, the vessel having at least one wall moulded from a plastics material; and a member comprising a reinforcing member at least partially encapsulated in the plastics material forming the at least one wall of said vessel to reinforce that at least one wall.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying Figures, in which:

Figure 1 shows a schematic representation of a vehicle incorporating a fuel tank assembly in accordance with an embodiment of the present invention;

Figure 2 shows a perspective view of the fuel tank assembly shown in Figure 1 comprising a moulded plastic vessel having integrated stiffening or reinforcing members in accordance with an embodiment of the present invention;

Figure 3 shows a schematic representation of the blow moulding process for forming the fuel tank assembly in accordance with an embodiment of the present invention;

Figure 4 illustrates a mesh structure of a stiffening or reinforcing member in accordance with an embodiment of the present invention; and

Figures 5A and 5B illustrate the forces applied to the fuel tank assembly due to changes in the internal pressure.

DETAILED DESCRIPTION

A fuel tank assembly 1 in accordance with an embodiment of the present invention will now be described with reference to the accompanying Figures. The fuel tank assembly 1 is configured to store a fuel, such as gasoline or diesel. The fuel tank assembly 1 has particular application in a vehicle V for supplying fuel to an internal combustion engine 2, as illustrated in Figure 1 . The vehicle V may, for example, be a hybrid electric vehicle comprising an electric traction motor (not shown). As shown in Figure 2, the fuel tank assembly 1 comprises a vessel 3 for storing fuel. In the present embodiment the fuel tank assembly 1 is a closed system which is at least substantially sealed to reduce emissions. The vessel 3 may be referred to as a fuel tank carcass. The vessel 3 comprises a sidewall 4, an upper wall 5 and a lower wall 6. As described herein, the vessel 3 is moulded from a plastics material. The fuel tank assembly 1 in the present embodiment is a saddle-type fuel tank assembly comprising first and second compartments 7-1 , 7-2 for positioning on opposing sides of a driveshaft (not shown) connected to the internal combustion engine 2. The fuel tank assembly 1 is positioned under the rear seat (not shown) of the vehicle V, but other configurations are also contemplated. The first and second compartments 7-1 , 7-2 are connected by a central bridging section 8 which extends over the driveshaft. The fuel tank assembly 1 comprises upper and lower stiffening or reinforcing members 9, 10 associated with the upper wall 5 and the lower wall 6 respectively. The upper and lower stiffening members 9, 10 are shown schematically in Figure 3. As described herein, the upper and lower stiffening members 9, 10 are integrated into the fuel tank assembly 1 . In particular, the upper and lower stiffening members 9, 10 are encapsulated within the upper wall 5 and the lower wall 6 respectively of the vessel 3. A fuel supply assembly 1 1 is provided in the upper wall 5 of the fuel tank assembly 1 for supplying fuel to the internal combustion engine 2. The fuel supply assembly 1 1 is fixedly mounted to the upper wall 5 by an encapsulated ring 12 which is incorporated into the upper wall 5 of the fuel tank assembly 1 in conventional manner.

The upper and lower stiffening members 9, 10 have a plurality of apertures 13 formed therein. In the present embodiment, the apertures 13 form a mesh structure in each of the upper and lower stiffening members 9, 10, as illustrated in Figure 4. The apertures 13 are sized to facilitate penetration of the molten plastics material such that, during moulding of the vessel 3, the upper and lower stiffening members 9, 10 are at least partially encapsulated, and preferably fully encapsulated, within the upper and lower walls 5, 6 respectively. The upper and lower stiffening members 9, 10 are each formed from a metal sheet. The apertures 13 may be formed in said sheet metal by a punching, stamping or cutting operation. Alternatively, the upper and lower stiffening members 9, 10 could comprise a woven mesh, for example a woven wire mesh. It will be understood that the upper and lower stiffening members 9, 10 may be formed from materials other than metal, for example a plastics material. The upper and lower stiffening members 9, 10 may comprise a mesh which is moulded from a plastics material, such as polyester or nylon. In a variant, the mesh could be woven from filaments, for example synthetic or carbon fibres. In the present embodiment, the upper and lower stiffening members 9, 10 are pre-formed into a shape at least substantially matching a profile of the upper and lower walls 5, 6 respectively. The upper and lower stiffening members 9, 10 may be formed by press forming the mesh to match the profile of the upper and lower walls 5, 6 of the vessel 3. It will be understood that the forming steps could be performed sequentially or simultaneously.

The fabrication of the fuel tank assembly 1 will now be described with particular reference to Figure 3. The vessel 3 is blow moulded in a mould apparatus 14 comprising first and second mould parts 15, 16 arranged to form a mould cavity (not shown). The first mould part 15 forms the upper wall 5 and the second mould part 16 forms the lower wall 6. At least one of the first and second mould parts 15, 16 is movable to open and close the mould apparatus 14. The pre-formed upper and lower stiffening members 9, 10 are inserted into the mould cavity 17 and secured in position. One or more mould clamps (not shown) may be provided for holding the upper and lower stiffening members 9, 10. The upper stiffening member 9 is held against (or proximal to) the first mould part 15; and the lower stiffening member 10 is held against (or proximal to) the second mould part 16. Fixtures and/or fittings may also be inserted into the mould apparatus 14 prior to moulding. For example, an encapsulated ring (not shown) may be introduced into the mould cavity. A parison 18 of plastics material is then introduced into the mould cavity (referred to as "dropping" the parison) between the first and second mould parts 15, 16. The mould apparatus 14 is closed and the parison 18 clamped between the first and second mould parts 15, 16. A compressed gas is introduced into the centre of the parison 18 causing the plastics material to be displaced outwardly towards an inner surface of the mould cavity. The plastics material contacts the upper and lower stiffening members 9, 10. While the parison 18 is molten, the plastics material is displaced through the apertures 13 such that the upper and lower stiffening members 9, 10 are encapsulated in the plastics material forming the upper and lower walls 5, 6 of the vessel 3. The upper and lower stiffening members 9, 10 are thereby integrated into the fuel tank assembly 1 . The continued introduction of compressed gas into the centre of the parison 18 displaces the molten plastics material against the inner surface of the mould cavity to form an exterior of the vessel 3. The plastics material is allowed to cool and the fuel tank assembly 1 is then removed from the mould cavity. It will be understood that the other components may be attached to the fuel tank assembly 1 in conventional manner. For example, a fuel pumping system may be attached to the fuel tank assembly 1 . In use, the fuel tank assembly 1 is a closed system and venting is inhibited. The pressure in the vessel 3 may cycle between high and low pressures which results in the application of forces on the fuel tank assembly 1 , as illustrated in Figures 5A and 5B. The high pressure may correspond to an increase of +350 mbar (above atmospheric pressure); and the low pressure may correspond to a decrease of -150 mbar (below atmospheric pressure). As illustrated in Figure 5A, the increase in the internal pressure applies a force to bias the upper and lower walls 5, 6 outwardly. As illustrated in Figure 5B, the decrease in the internal pressure applies a force to bias the upper and lower walls 5, 6 inwardly. The upper and lower stiffening members 9, 10 in accordance with the present embodiment are configured to reduce or prevent deformation of the fuel tank assembly 1 as the internal pressure changes in use. It will be appreciated that various modifications may be made to the embodiment(s) described herein without departing from the scope of the appended claims. The present invention has been described with particular reference to a fuel tank for vehicle. It will be appreciated that the invention(s) described herein may be used for other applications, for example to form a vessel which is subject to pressure changes.