GB2559348B

GB2559348B - Fuel tank method and apparatus

Info

Publication number: GB2559348B
Application number: GB1701623.9A
Authority: GB
Inventors: Towers Kyle
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2017-02-01
Filing date: 2017-02-01
Publication date: 2019-06-05
Anticipated expiration: 2037-02-01
Also published as: GB201701623D0; GB2559348A

Description

FUEL TANK METHOD AND APPARATUS

TECHNICAL FIELD

The present disclosure relates to a method of forming a fuel tank assembly; to an internal reinforcing assembly; to a fuel tank assembly and to a vehicle.

BACKGROUND A fuel tank is provided in a vehicle to store fuel, such as gasoline or diesel fuel, for an internal combustion engine. The fuel tank may comprise a vessel moulded from a plastics material. 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 known to vent fuel tanks to the atmosphere. However, any vapours vented from the fuel tank must be controlled in order to manage emissions and keep within legislated limits. 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. To withstand the loads resulting from the positive and negative changes in the internal pressure, the fuel tank may be reinforced. One or more bracing element may be provided internally to reinforce the vessel. The bracing element(s) typically extend between opposing walls of the fuel tank. The bracing element may comprise a metal beam having a U-section which is mounted internally by plastic cups which are welded to the walls of the vessel during the blow-moulding process. If the beam is overly long or heavy, the beam may move during the blow-moulding process, for example by sagging. This movement typically results in the moulded vessel being scrapped. The beams therefore have an upper length limit above which they are difficult to install reliably. In certain situations it may be necessary or desirable to install longer beams, for example to overcome packaging constraints for the fuel tank.

It is known from EP 2511068 to install two parts of a reinforcing element in a fuel tank during moulding. After the fuel tank has been moulded, the two parts are connected by inserting a third connector or releasing a spring mechanism to join the two parts. This arrangement requires access to the parts, for example through an aperture in the fuel tank.

It is against this background that the fuel tank and internal reinforcing assembly in accordance with aspects of the present invention have been conceived.

SUMMARY OF THE INVENTION

Aspects of the present invention relate to a fuel tank assembly; to an internal reinforcing assembly; to a fuel tank assembly and to a vehicle as claimed in the appended claims.

According to a further aspect of the present invention there is provided a method of forming a fuel tank assembly, the fuel tank assembly comprising a vessel and at least one internal reinforcing assembly, each said internal reinforcing assembly comprising first and second reinforcing members, at least one of said first and second reinforcing members comprising coupling means; the method comprising: introducing a plastics material into a mould; displacing the plastics material against an interior of the mould to form opposing first and second walls of the vessel; mounting the first and second reinforcing members to said first and second walls respectively; and closing the mould to seal the vessel; wherein the coupling means forms a coupling between the first and second reinforcing members as the mould is closed. The closing of the mould to seal the vessel causes the coupling means to form the coupling which couples the first and second reinforcing members together. Thus, at least in certain embodiments, the internal reinforcing assembly may be formed without a subsequent operation. Furthermore, it is not necessary for the coupling means to be accessible from the outside of the moulded vessel. The first and second reinforcing members are aligned as the mould is closed. The plastics material is in a molten or semi-molten state as the mould is closed. The plastics material is pliable to allow the orientation of the first and second reinforcing members to be adjusted.

The method may comprise installing a single internal reinforcing assembly in the vessel; or installing a plurality of said internal reinforcing assemblies in the vessel. The location of the internal reinforcing assemblies may be selected depending on the design and/or configuration of the vessel. It will be appreciated that the dimensions, for example length, of the internal reinforcing assemblies may be altered for particular applications. In applications comprising a plurality of said internal reinforcing assemblies, the internal reinforcing assemblies may all have the same length or different lengths depending on their position within the vessel.

The mould may be temporarily sealed in an intermediate process for forming the first and second walls of the vessel. The mould may then be re-opened and the first and second reinforcing members mounted to the first and second walls of the vessel.

The at least one internal reinforcing assembly may be introduced into the mould before the plastics material is displaced against the interior of the mould to form the first and second walls of the vessel. Alternatively, the at least one internal reinforcing assembly may be introduced into the mould after the plastics material is displaced against the interior of the mould to form the first and second walls of the vessel.

The first and second mounting means are mounted to the first and second walls when the plastics material is supported by the mould. The first and second mounting means may be brought into contact with the plastics material while the plastics material is in contact with (and supported by) the interior of the mould. A force may be applied to weld the first and second mounting means to the respective first and second walls of the vessel. The first and second mounting means may be displaced into the plastics material forming the first and second walls respectively.

The at least one internal reinforcing assembly may be supported on a core which is introduced into the mould. The core may be suitable for temporarily sealing the mould, for example if the at least one internal reinforcing assembly is introduced into the mould before the first and second walls of the vessel are formed. The core may be removed from the mould after the first and second reinforcing members are mounted to the first and second walls of the vessel. The mould may be closed to seal the vessel after the core is removed. The core may comprise one or more actuator for displacing the first and second reinforcing members such that the first and second mounting means contact the first and second walls.

The mould may comprise at least first and second mould parts. At least one of the first and second mould parts may be movable along a first axis to open and close the mould. The first and second walls of the vessel may be formed by the first and second mould parts respectively. The first and second reinforcing members have respective first and second longitudinal axes. At least in certain embodiments, the first and second reinforcing members may be mounted to the first and second walls such that said first and second longitudinal axes extend substantially parallel to said first axis.

The first reinforcing member may comprise a first pillar or tube. The second reinforcing member may comprise a second pillar or tube.

The first reinforcing member comprises a first coupling means. The second reinforcing member comprises a second coupling means. The first and second coupling means comprise respective first and second interlocking features. The first and second interlocking features engage with each other as the mould is closed to form said coupling.

At least one of said first and second reinforcing members may comprise alignment means for aligning said first and second reinforcing members. The first reinforcing member may comprise a first alignment means. The second reinforcing member may comprise a second alignment means. The first and second alignment means may cooperate with each other to align said first and second reinforcing members as the mould is closed. The first and second alignment means may comprise cooperating male and female surfaces. The male and female surfaces may comprise substantially conical male and female surfaces. In alternate arrangements the surfaces may be part-spherical, for example hemispherical; or part-elliptical. The male and female surfaces may be inclined at an acute angle to the first axis along which at least one of said first and second mould parts is movable.

Displacing the plastics material against a sidewall of the mould may comprise sealing the mould and changing the gas pressure in the mould. The gas pressure in the mould may be increased by introducing gas at a pressure greater than atmospheric pressure. Alternatively, gas pressure in the mould may be reduced, for example by forming a vacuum in the mould.

The plastics material may be introduced into the mould in a molten or semi-molten state. The plastics material may be introduced into the mould as first and second sheets. The at least one reinforcing member may be supported centrally in the mould. The first and second sheets may be dropped on opposing sides of the at least one internal reinforcing member. The plastics material may be introduced into the mould at the same time as, or after the at least one reinforcing member is introduced into the mould. The first and second reinforcing members may be displaced in opposite directions to mount the first and second reinforcing members.

The first reinforcing member may comprise a first mounting means. The second reinforcing member may comprise a second mounting means. The first and second mounting means may comprise respective first and second weld plates.

According to a further aspect of the present invention there is provided an internal reinforcing assembly for a moulded fuel tank assembly having a vessel, the internal reinforcing assembly comprising: a first reinforcing member for mounting to a first wall of the vessel; and a second reinforcing member for mounting to a second wall of the vessel; wherein at least one of said first and second reinforcing members comprises coupling means, the coupling means being arranged to couple the first and second reinforcing members to each other when they are brought together during moulding of the vessel. The first wall may be formed by a first mould part. The second wall may be formed by a second mould part. The first and second mould part may be brought together during moulding of the vessel. The first wall may be formed by the first mould part and the second wall may be formed by the second mould part.

The first reinforcing member and/or the second reinforcing member may comprise a single component. This may allow the mass of the first reinforcing member and/or the second reinforcing member to be reduced, at least in certain embodiments.

The first and second reinforcing member may be formed of a fuel-resilient material. The first and second reinforcing member may be formed of plastic or metal, for example.

The first reinforcing member may comprise first coupling means. The second reinforcing member may comprise second coupling means. The first and second coupling means may be arranged to form a coupling between said first and second reinforcing members. The coupling may be a permanent coupling.

The first and second coupling means may comprise respective first and second interlocking features. The first and second interlocking features may, for example, comprise interlocking male and female features. Other coupling arrangements may be implemented.

The internal reinforcing assembly may have a fixed length. The internal reinforcing assembly may be arranged to extend between said first and second walls of the vessel.

The internal reinforcing assembly may consist of or comprise said first and second reinforcing members.

At least one of said first and second reinforcing members may comprise alignment means for aligning the first and second reinforcing members with each other. The first reinforcing member may comprise first alignment means. The second reinforcing member may comprise second alignment means. The first and second alignment means may comprise respective first and second alignment features for cooperating with each other to align said first and second reinforcing members with each other.

The first and second alignment features may comprise cooperating male and female surfaces. The male and female surfaces may comprise substantially conical male and female surfaces.

The first and second reinforcing members may comprise first and second longitudinal axes respectively. The male and female surfaces may be inclined at an acute angle to said first and second longitudinal axes.

The first reinforcing member may comprise a first mounting means for mounting the first reinforcing member to the first wall. The second reinforcing member may comprise a second mounting means for mounting the second reinforcing member to the second wall. The first and second mounting means may, for example, comprise first and second weld plates. The first and second weld plates may be suitable for forming a plastic weld with the plastics material forming the first and second walls of the vessel.

According to a further aspect of the present invention there is provided a fuel tank assembly comprising at least one internal reinforcing assembly as described herein.

According to a further aspect of the present invention there is provided a vehicle comprising a fuel tank assembly as described herein.

Within the scope of the claims it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, 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.

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 in accordance with an embodiment of the present invention;

Figure 3 shows a longitudinal sectional view of an internal reinforcing assembly disposed in the fuel tank assembly shown in Figure 2;

Figure 4 shows a perspective view of the separate components of the internal reinforcing assembly shown in Figure 3; and

Figures 5A, 5B and 5C are schematic representations of the moulding process for moulding the vessel shown in Figure 3 in accordance with an aspect of the present invention.

DETAILED DESCRIPTION A fuel tank assembly 1 in accordance with an embodiment of the present invention will now be described with reference to Figures 1,2 and 3. 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 an automobile.

With reference to Figure 2, the fuel tank assembly 1 comprises a vessel 3 for storing fuel. 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 an internal reinforcing assembly 9. It will be understood that a plurality of internal reinforcing assemblies 9 may be installed in the fuel tank assembly 1, but only one is described herein for the sake of brevity. A longitudinal sectional view of the internal reinforcing assembly 9 is shown in Figure 3. The internal reinforcing assembly 9 has a fixed length and extends between said upper and lower walls 5, 6. The internal reinforcing assembly 9 comprises a first reinforcing member 10 for mounting to the upper wall 5; and a second reinforcing member 11 for mounting to the lower wall 6. In the present embodiment the first reinforcing member 10 comprises a first pillar and the second reinforcing member 11 comprises a second pillar. The first and second pillars 10, 11 are connected to each other to provide an internal brace for the upper and lower walls 5, 6 of the vessel 3. As described herein, the first and second pillars 10, 11 are connected to each other during moulding of the vessel 3. The first and second pillars 10, 11 have respective first and second longitudinal axis X1, X2 which are at substantially aligned with each other when the internal reinforcing assembly 9 is installed in the vessel 3, as illustrated in Figure 3.

The first and second pillars 10, 11 are shown in Figure 4. The first pillar 10 comprises a first mounting means 12; a first coupling means 13; and a first alignment means 14. The first mounting means 12 comprises a first base 15 defining a first welding surface 16 for welding to the upper wall 5. The first base 15 comprises a first truncated cone to enlarge the first welding surface 16 for mounting the first pillar 10. The first welding surface 16 may optionally comprise one or more aperture (not shown) into which plastics material is displaced during moulding of the vessel 3 to form a mechanical interlock with the upper wall 5. The first coupling means 13 comprises one or more first projection 17. The first alignment means 14 comprises a female conical surface 18 disposed at the end of the first pillar 10 distal from the first welding surface 16. A first annular surface 19 is formed at the distal end of the first pillar 10 and extends around a base of the female conical surface 18 to form a first contact surface. The first pillar 10 has a unitary construction and is moulded from a plastics material in the present embodiment. In a variant, the first pillar 10 may comprise multiple components which may be formed of plastic and/or metal.

The second pillar 11 comprises a second mounting means 20; a second coupling means 21; and a second alignment means 22. The second mounting means 20 comprises a second base 23 defining a second welding surface 24 for welding to the lower wall 6. The second base 23 comprises a second truncated cone to enlarge the second welding surface 24 for mounting the second pillar 11. The second welding surface 24 may optionally comprise one or more aperture (not shown) into which plastics material is displaced during moulding of the vessel 3 to form a mechanical interlock with the lower wall 6. The second coupling means 21 comprises one or more second projection 25. The second alignment means 22 comprises a male conical surface 26 disposed at a distal end of the second pillar 11. A second annular surface 27 extends around the base of the male conical surface 26 to form a second contact surface. The second pillar 11 has a unitary construction and is moulded from a plastics material in the present embodiment. In a variant, the second pillar 11 may comprise multiple components which may be formed of plastic and/or metal.

The first and second alignment means 14, 22 are arranged to cooperate with each other. In particular, the female conical surface 18 and the male conical surface 26 have matching profiles. The male conical surface 26 is configured to locate in the female conical surface 18 when the first and second pillars 10, 11 are brought together. The female conical surface 18 acts as a guide to align the first and second pillars 10, 11 with each other. The conical arrangement of the first and second alignment means 14, 22 is particularly advantageous as the first and second pillars 10, 11 are self-centring. The first and second annular surfaces 19, 27 abut each other to provide a mechanical stop. The first and second coupling means 13, 21 are configured to cooperate with each other to form a mechanical connection between said first and second pillars 10, 11. The first coupling means 13 may comprise one or more first projection 17; and the second coupling means 21 may comprise one or more second projection 25. The first and second projections 17, 25 interlock with each other to form the mechanical connection between said first and second pillars 10, 11. The first and second projections 17, 25 may form a clip or latch together to connect said first and second pillars 10, 11. Other types of connectors, for example male and female connectors, may be used to form said connection.

The fabrication of the fuel tank assembly 1 will now be described. The first and second pillars 10, 11 are pre-formed by a moulding process. The vessel 3 is blow moulded in a mould 28 having first and second mould parts 29, 30. The first mould part 29 is configured to form the upper wall 5 of the vessel 3 and the second mould part 30 is configured to form the lower wall 6 of the vessel 3. The first and second mould parts 29, 30 are arranged such that the vessel 3 is moulded on its side, with the upper and lower walls 5, 6 extending vertically. The first and second mould parts 29, 30 are movable relative to each other along a first axis X to open and close the mould 28. The first and second mould parts 29, 30 form a cavity 31 having an internal wall which defines an exterior surface of the vessel 3.

The internal reinforcing assembly 9 is introduced into the mould cavity 31 on a core 32 which is movable relative to the mould 28, as shown in Figure 5A. The core 32 comprises actuators (not shown) for displacing the first and second pillars 10,11 outwardly parallel to said first axis X. The actuators are initially retracted such that the first and second pillars 10, 11 do not obstruct the introduction of the plastics material into the mould cavity 31. When the core 32 is in position, the plastics material is introduced into the mould cavity 31. In the present embodiment, the plastics material is dropped as first and second sheets S1, S2 of molten (or semi-molten) plastics material. In a first closing operation, the first and second mould parts 29, 30 are displaced along said first axis X to an intermediate position to form a seal with upper and lower members mounted to the core 32. A compressed gas is then introduced into the mould cavity 31 to displace the first and second sheets S1, S2 of plastics material outwardly against the internal wall of the mould cavity 31. The mould cavity 31 defines the external profile of the vessel 3 and the first and second sheets S1, S2 adopt an intermediary form. After displacing the plastics material against the first and second mould parts 29, 30, the actuators mounted to the core 32 are extended to displace the first and second pillars 10, 11 outwardly. The first and second welding surfaces 16, 24 contact the plastics material forming the upper and lower walls 5, 6 and plastic welds are formed to mount said first and second pillars 10, 11, as shown in Figure 5B. The gas pressure in the mould cavity 31 may be maintained during this operation.

Once the first and second pillars 10, 11 are mounted to the upper and lower walls 5, 6, the actuators on the core 32 are controlled to release the first and second pillars 10, 11. The actuators are then retracted to reduce the profile of the core 32. The first and second mould parts 29, 30 are displaced to open the mould 28 and the core 32 is removed from the mould cavity 31. The plastics material remains in the first and second mould parts 29, 30 and first and second circumferential flanges 33, 34 are exposed. In a second closing operation, the first and second mould parts 29, 30 are displaced along the first axis X to close the mould 28. The first and second circumferential flanges 33, 34 are brought into contact with each other to form a join line 35 to seal the vessel 3, as shown in Figure 5C. It will be understood that the join line 35 extends circumferentially around the sidewall 4 of the vessel 3.

The first and second pillars 10, 11 are configured to engage each other during the second closing operation. In particular, as the first and second mould parts 29, 30 are brought together to close the mould 28, the male conical surface 26 of the second pillar 11 is introduced into the female conical surface 18 of the first pillar 10. The female conical surface 18 acts as a guide to align the first and second pillars 10, 11 such that said first and second longitudinal axis X1, X2 are at least substantially aligned with each other. The first and second annular surfaces 19, 27 are configured to abut each other when the first and second mould parts 29, 30 are at least substantially closed. The first and second coupling means 13, 21 cooperate with each other to form a mechanical connection between said first and second pillars 10, 11. The first and second pillars 10, 11 are connected to each other to form the internal reinforcing assembly 9.

The plastics material is allowed to cool and the fuel tank assembly 1 is then removed from the mould 28. It will be appreciated that the internal reinforcing assembly 9 is installed without any additional processing steps or tooling. The internal reinforcing assembly 9 can be installed without needing to have access after the vessel 3 has been moulded. The fuel tank assembly 1 may be completed by adding fittings and fixtures in convention manner after the vessel 3 has been removed from the mould 28.

The tendency of the first and second pillars 10,11 to sag or move during the moulding process is reduced as they extend only partway between the upper and lower walls 5, 6 of the vessel 3. The overall length of the internal reinforcing assembly 9 may thereby be increased over prior art arrangements. Furthermore, the provision of first and second alignment means 14, 22, helps to align the first and second pillars 10, 11 as the mould parts 29, 30 are brought together to close the mould 28 and seal the vessel 3.

The first and second coupling means 13, 21 in the embodiment described herein comprises interlocking projections which cooperate with each other to couple the first and second pillars 10, 11 to each other. Alternative coupling means may be used. For example, an adhesive or bonding agent may be used to couple the first and second pillars 10, 11. Alternatively, a weld may be formed to couple said first and second pillars 10, 11.

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.

Claims

CLAIMS:

1. A method of forming a fuel tank assembly, the fuel tank assembly comprising a vessel and at least one internal reinforcing assembly, each said internal reinforcing assembly comprising first and second reinforcing members, at least one of said first and second reinforcing members comprising coupling means; the method comprising: introducing a plastics material into a mould; displacing the plastics material against an interior of the mould to form opposing first and second walls of the vessel; mounting the first and second reinforcing members to said first and second walls respectively; and closing the mould to seal the vessel; wherein the coupling means forms a coupling between the first and second reinforcing members as the mould is closed, the first reinforcing member having a first coupling means, and the second reinforcing member having a second coupling means, wherein said first and second coupling means comprise respective first and second interlocking features, the first and second interlocking features engaging with each other as the mould is closed to form said coupling.

2. A method as claimed in claim 1, wherein the mould comprises first and second mould parts , at least one of the first and second mould parts being movable along a first axis to open and close the mould, wherein the first and second walls of the vessel are formed by the first and second mould parts respectively.

3. A method as claimed in claim 2, wherein the first and second reinforcing members have respective first and second longitudinal axes, the first and second reinforcing members being mounted to the first and second walls such that said first and second longitudinal axes extend substantially parallel to said first axis.

4. A method as claimed in any one of the preceding claims, wherein at least one of said first and second reinforcing members comprising alignment means.

5. A method as claimed in claim 4, wherein the first and second reinforcing members comprise respective first and second alignment means; the first and second alignment means cooperating with each other to align said first and second reinforcing members as the mould is closed.

6. A method as claimed in claim 5, wherein said first and second alignment means comprise cooperating male and female surfaces.

7. A method as claimed in claim 6, wherein said male and female surfaces comprise substantially conical male and female surfaces.

8. A method as claimed in claim 6 or claim 7 when dependent directly or indirectly on claim 2, wherein said male and female surfaces are inclined at an acute angle to said first axis.

9. A method as claimed in any one of the preceding claims, wherein displacing the plastics material against a sidewall of the mould comprises sealing the mould and changing the gas pressure in the mould.

10. An internal reinforcing assembly for a moulded fuel tank assembly having a vessel, the internal reinforcing assembly comprising: a first reinforcing member for mounting to a first wall of the vessel; and a second reinforcing member for mounting to a second wall of the vessel; wherein at least one of said first and second reinforcing members comprises coupling means, the coupling means being arranged to couple the first and second reinforcing members to each other when they are brought together during moulding of the vessel.

11. An internal reinforcing assembly as claimed in claim 10, wherein the first reinforcing member comprises first coupling means; and the second reinforcing member comprises second coupling means.

12. An internal reinforcing assembly as claimed in claim 11, wherein said first and second coupling means comprise respective first and second interlocking features.

13. An internal reinforcing assembly as claimed in any one of claims 10, 11 or 12, wherein the internal reinforcing assembly has a fixed length and is arranged to extend between said first and second walls of the vessel.

14. An internal reinforcing assembly as claimed in any one of claims 10 to 13, wherein the internal reinforcing assembly consists of said first and second reinforcing members.

15. An internal reinforcing assembly as claimed in any one of claims 10 to 14, wherein at least one of said first and second reinforcing members comprises alignment means for aligning the first and second reinforcing members with each other.

16. An internal reinforcing assembly as claimed in claim 15, wherein the first reinforcing member comprises first alignment means; and the second reinforcing member comprises second alignment means.

17. An internal reinforcing assembly as claimed in claim 16, wherein said first and second alignment means comprise respective first and second alignment features for cooperating with each other to align said first and second reinforcing members with each other.

18. An internal reinforcing assembly as claimed in claim 17, wherein said first and second alignment features comprise cooperating male and female surfaces.

19. An internal reinforcing assembly as claimed in claim 18, wherein said male and female surfaces comprise substantially conical male and female surfaces.

20. An internal reinforcing assembly as claimed in claim 18 or claim 19, wherein the first and second reinforcing members have first and second longitudinal axes respectively, the male and female surfaces being inclined at an acute angle to said first and second longitudinal axes.

21. An internal reinforcing assembly as claimed in any one of claims 10 to 20, wherein the first reinforcing member comprises a first mounting means for mounting the first reinforcing member to the first wall; and the second reinforcing member comprises a second mounting means for mounting the second reinforcing member to the second wall.

22. A fuel tank assembly comprising at least one internal reinforcing assembly as claimed in any one of claims 10 to 21.

23. A vehicle comprising a fuel tank assembly as claimed in claim 22.