GB2421499A - A refuelling aid to prevent improper fuel being used - Google Patents

Abstract

A vehicle refuelling aid (10) is provided for preventing improper or incorrect fuel being used to fill a fuel tank. The aid is adapted to prevent smaller diameter fuel nozzles (for example unleaded petrol nozzles) being inserted into larger diameter fuel tank apertures (for example diesel tank apertures). The aid comprises a locking member (25) and an obstruction member (30). The locking member is movable from a locked position to an unlocked position and the obstruction member is movable from an obstructing position in which it prevents passage of a fuel nozzle to an unobstructing position in which a fuel nozzle can pass into a fuel tank (50). The locking member is operable to lock the obstruction member in the obstructing position when in its locked position and to release the obstruction member when in its unlocked position. The locking member is movable to the unlocked position only by a fuel nozzle (36) having a diameter which exceeds a predetermined threshold (d). Accordingly fuel nozzles (35) not exceeding the threshold are obstructed.

Description

A REFUELLING AID

The present invention relates generally to the fuelling of vehicles and more particularly to preventing the use of an improper and unsuitable fuel source.

At present the most common forms of fuel used for vehicles are petrol and diesel.

The standard sizes for filling nozzles used to supply petrol and diesel are different.

For example, typically an unleaded petrol nozzle has an external diameter of 21mm, a lead replacement petrol nozzle has an external diameter of 25mm and a diesel nozzle has an external diameter of 23mm.

It is known, for example from US 3,880,317 and GB 2 230 765, to provide filler necks with restricted filling apertures which are sized to receive unleaded petrol fuel nozzles but not larger diameter nozzles. This does not, of course, prevent unleaded petrol nozzles being inserted into the fuel tanks of vehicles requiring fuels which are delivered with larger diameter nozzles. For example, the filling of diesel fuel tanks with unleaded petrol is not uncommon. The result of such a mistake is that the diesel fuel system must be purged of all unleaded petrol which can be costly and is time consuming. In more extreme cases the diesel engine may breakdown or even be seriously damaged if unleaded petrol is run through it.

The present invention attempts to reduce the possibility of filling a vehicle fuel tank with an incorrect fuel.

According to a first aspect of the present invention there is provided a device for preventing improper fuel being used to fill a fuel tank, the device comprising a locking member and an obstruction member. The locking member is moveable from a locked position to an unlocked position and the obstruction member is moveable from an obstructing position in which it prevents a passage of a fuel nozzle to an unobstructing position in which a fuel nozzle can pass into a fuel tank.

The locking member is operable to lock the obstruction member in the obstructing position when in its locked position and to release the obstruction member when in its unlocked position. The locking member is moveable to the unlocked position only by a fuel nozzle having a diameter which exceeds a predetermined threshold such that fuel nozzles not exceeding the threshold are obstructed by the obstruction member.

The present invention therefore prevents smaller diameter fuel nozzles being incorrectly inserted into larger diameter fuel tank apertures.

The device may include attachment means for enabling it to be attached within a fuel tank filler neck. The bore of the fuel tank filler neck is a convenient position for such a device to be situated and means that the fuel tank nozzle cannot be inserted into the fuel tank itself. Because the fuel nozzle cannot be inserted to its usual depth the user is alerted to the fact that the fuel nozzle should not be used.

Moreover, because the obstruction member restricts access to the fuel tank even if fuel is delivered it will bubble back up the filler neck and activate the automatic shut-off sensor on the fuel nozzles to stop the fuel delivery. In other embodiments, the device may be adapted to fit within the fuel tank itself or at any point in the fuelling arrangement where the device can obstruct the entry of an incorrect nozzle into the fuel tank and prevent the flow of incorrect fuel into the fuel tank.

The general principle of the present invention is that the diameter threshold should be set so that fuel nozzles having a lesser diameter cannot overcome the obstruction provided by the device. The predetermined diameter threshold may be set by the diameter of a diesel fuel nozzle. Accordingly unleaded petrol fuel nozzles would be obstructed. In other words the present invention may provide a device for preventing the misfuelling of a diesel-powered vehicle based on the dimension of a diesel fuel nozzle.

The device may also include or he used in conjunction with a restrictor element which defines an upper diameter threshold so that, for example, lead replacement petrol nozzles could not be inserted past the restriction but diesel and unleaded petrol nozzles could pass the restriction where the secondary "size filter" of the device can then operate to distinguish diesel and unleaded petrol nozzles.

The device may be substantially toroidal and this would be advantageous if the device is intended to be inserted into the bore of a generally cylindrical fuel filler neck. Other shapes of the device are possible as long as an interior passage suitable for a nozzle of the required size can be formed through it.

The locking member may be biased towards the locked position so that it is automatically reset to the locked position once a nozzle is removed following use.

The obstruction member may be biased towards the obstructing position so that it is automatically reset to the obstruction position once the nozzle has been removed following use.

The obstruction member may comprise a flap or the like which can be pivoted away from the remainder of the device to remove the obstruction. The flap would be held in the unobstructing position by the nozzle during refuelling and would return to the obstructing position once the nozzle was withdrawn.

The locking member may comprise an engagement surface which is engageable by a fuel nozzle exceeding the predetermined threshold to move the locking member to the unlocked position. The fuel nozzle therefore effectively pushes the locking member out of its way by engaging the engagement surface and using it to push the locking member to its unlocked position. The engagement surface of the locking member may comprise a curved surface and in one embodiment the engagement surface may comprise a roller. The use of a curved surface such as a roller minimises the extent of the engagement surface required so that the maximum amount of displacement of the locking member can be produced by the minimum amount of nozzle insertion. Accordingly the overall thickness of the device can be minimised.

A device of minimised dimensions, particularly in terms of its thickness, would be particularly advantageous for devices intended to be retrofitted to existing fuel filling systems. This would prevent problems, for example, with devices being too large for fuel tank filler necks.

The device may further be provided with alarm means for indicating if the obstruction member is moved without the locking member having first been moved to the unlocked position. This would be useful for the case where a fuel nozzle not having the required diameter is forced into a fuel tank filler neck and the obstruction member is forced to its unobstructing member by the nozzle. The alarm means could be provided by an suitable visible or audible warning which is deactivated when the locking member is moved to the locking position so that unwanted activation of the alarm means is prevented.

The present invention also provides a fuel tank filler neck having a device as described hereinabove. The device may be provided as an integral part of the fuel tank filler neck or may be provided as a separate element which can be added to a pre-existing filler neck.

The present invention also provides a fuel tank safety device providing a first gate and a second gate, the first gate being adapted to hold the second gate in an obstructing position which prevents the passage of a fuel nozzle into a fuel tank.

The first gate is moveable to a release position in which the second gate can be moved so as not to obstruct the passage of a fuel nozzle. The first gate is moveable only by a fuel nozzle having a diameter in excess of a predetermined threshold.

Accordingly in use the device prevents a fuel filling nozzle being inserted except where the fuel nozzle has an external diameter suflicient to engage the first gate to move it and disengage it from the second gate.

The present invention also provides a retrofittable safety device for a diesel refuelling arrangement, the device comprising means for preventing the passage of an unleaded fuel nozzle into a diesel fuel tank which can be overcome by a diesel fuel nozzle to allow it to pass into the fuel tank.

By providing a retrofittable device which can be inserted at some point in the refuelling arrangement, such as the filler neck, the advantages of the safety device can be provided to existing vehicles as well as newly built vehicles.

The present invention also provides a vehicle fitted with a device as described hereinabove.

The present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure lA is a diagrammatic plan view of a refuelling aid formed according to the present invention shown with a locking member in a locked position; Figure lB is a section of the refuelling aid shown in Figure IA taken along line I-I; Figure 2A is a diagrammatic plan view of the refuelling aid of Figure IA shown with the locking member in an unlocked position; Figure 2B is a section of the refuelling aid of Figure 2A taken along line II- 11; Figure 3A is a section of the refuelling aid of Figures 1 and 2 shown with a locking member in a locked position and an obstruction member in an obstructing position; Figure 3B is a section of the device shown in Figure 3A when presented with a fuel nozzle having a diameter less than a predetermined threshold; Figure 3C is a section of the device of Figure 3A shown when presented initially with a fuel nozzle exceeding a predetermined threshold; Figure 3D is a section of the refuelling aid of Figure 3C shown as the fuel nozzle initially engages the locking member; Figure 3E is a section of the refuelling aid of Figure 3D when the fuel nozzle has moved the locking member to an unlocked position; Figure 3F is a section of the refuelling aid of Figure 3E showing the obstruction member in an unobstructing position; Figure 4 is a diagrammatic plan view of a refuelling aid formed according to an alternative embodiment; Figure 5A is a section of a refuelling aid formed according to an alternative embodiment shown with a locking member in a locked position; Figure 5B is a section of the refuelling aid of Figure 5A shown with the locking member in an unlocked position; Figure 6 is a section of a refuelling aid incorporating a size restricting element; Figure 7 is a section of a fuel tank illustrating various positions at which a refuelling aid formed according to the present invention might be fitted; Figure 8 is a section of a fuel filler neck having an integrated refuelling aid formed according to the present invention; Figure 9A is a top perspective view of a device formed according to an alternative embodiment; Figure 9B is a perspective view of the device of Figure 9A shown with a top wall and interior wall removed to illustrate the working mechanism; Figure 9C is a bottom perspective view of the device of Figure 9A; Figure 9D is a plan view of the device shown in Figure 9B; Figure 9E is a plan view of the device shown in Figure 9D with locking elements removed to illustrate resilient biasing elements; Figure 10 is a perspective view of the device of Figure 9 presented with a fuel nozzle; Figure 1 IA is a section of part of the device shown in Figures 9 and 10 when presented with an unleaded petrol nozzle; Figure IIB is a section of the device shown in Figure hA following insertion of the nozzle into the device; Figure 1 1C is a section of part of the device shown in Figures 9 and 10 when presented with a diesel fuel nozzle; Figure 1 1D is a section of the device shown in Figure 1 IC following initial insertion of the fuel nozzle; Figure 1 IE is a section of the device shown in Figure 1 1D following successful continued insertion of the fuel nozzle passed an obstruction member; Figure 11 F is a section of the device shown in Figure 1 1 E as the nozzle is partially removed; Figure l2A is a perspective view of a part of a device according to an alternative embodiment shown in a locked position; and Figure 12B is a perspective view of the device shown in Figure l2A shown in an unlocked position.

Referring first to Figures IA and I B there is shown a refuelling aid generally indicated 10 comprising a toroidal body 15.

The body 15 includes a semicircular cavity 20 which accommodates a semicircular locking member 25.

The body 15 also supports an obstructing member 30 in the form of a diskshape flap which fits within the aperture of the toroidal body 15.

The locking member 25 comprises a generally circular roller member 26 carried on a base 27. In this embodiment the roller member 26 comprises a bead-like projection whose curved surface extends radially inwardly into the body aperture.

The base 27 includes a foot 28 which projects radially inwardly below the roller member 26 so as to define a shelf on which the periphery of the obstruction member 30 sits.

Diametrically opposed the position of the foot 27 the obstruction member 30 is S pivotally connected to the body 15 at a pivot point 3 I. Accordingly it will be seen that with the aid 10 in this configuration the obstruction member is locked in the position shown because it is secured on one side at the pivot point 31 and prevented from pivoting motion by virtue of its position on top of the foot 28 and below the roller member 26.

Referring now to Figure 2A and 2B, the locking member 25 is shown moved radially outwardly further into the cavity 20 to the unlocked position shown. In this position it will be seen that the foot 28 no longer rests under the obstruction member periphery and accordingly the obstruction member 30 would be free to pivot about the pivot point 31.

In Figures 2A and 2B therefore the locking member 25 is shown in an unlocked position and the obstruction member 30 can be moved from the obstructing position shown in solid lines to the unobstructing position shown in dotted lines.

Referring now Figures 3A to 3F the working of the refuelling aid 10 shown in Figures I and 2 is described.

In Figure 3A the refuelling aid 10 is shown in its resting position in which the locking member 25 is in its most radially inward locked position and the obstruction member 30 is retained in its obstructing position by the locking member 25.

A diameter threshold d is defined by the distance between the pivot point 3 I and the axial tangent line of the outer surface of the roller member 26 plus a distance defined by the radial extent to which the foot 27 underlies the flap 30 which reflects the radial distance by which the locking member 25 must be moved to disengage the foot 28.

In Figure 3B an unleaded petrol nozzle 35 having a diameter dl is introduced into the aid 10. The diameter dl is below a diameter threshold d and is not of sufficient diameter to engage the roller 26. The nozzle 35 abuts against the obstruction member 30 without having first moved the locking member 25 to its unlocked position. Accordingly the nozzle 35 cannot push the obstruction member 30 downwardly about its pivot point because the obstruction member 30 cannot pass over the foot 28.

Referring now to Figure 3C a diesel fuel nozzle 36 having a diameter d2 is shown introduced into the refuelling aid 10. The diameter d2 is equal to the diameter d and accordingly it is of sufficient diameter to engage the roller 26. As the nozzle 36 is inserted it forces the locking member 25 radially outwardly by its progressive engagement with the roller 26 outer surface as shown in Figure 3D.

Because the aid uses a roller with a spherical outer surface the vertical distance the nozzle must travel in order to displace the roller radially outwardly a given distance is minirnised so that the overall thickness of the aid can therefore also be minimised.

In Figure 3E the nozzle 36 is shown at the point at which it engages the obstruction member 30, at which point the locking member 25 has fully retracted and the foot 28 no longer restricts movement of the obstruction member 30. Therefore continued insertion of the fuel nozzle 36 now pivots the obstruction member about the pivot point 31 SO that the nozzle 36 can pass through the refuelling aid as shown in Figure 3F.

Once refuelling has been completed the nozzle 36 is withdrawn and in this embodiment the obstruction member 30 is resiliently biased towards is obstructing position by the hinge 31 so that as the nozzle is withdrawn the obstruction member pivots back up to the obstructing position shown in Figure 3E. In addition, the locking member 25 is resiliently biased towards its locking position; this may be achieved by a spring arrangement (not shown) or by a resilient material such as rubber positioned in the cavity into which the locking member is pushed as the nozzle is inserted. When the nozzle 36 is withdrawn further as shown in Figures 3D and 3C the locking member 25 returns to its locking position shown in Figure 3C so that the refuelling aid is reset with the locking member in its locking position and the obstruction member in its obstructing position ready for a further attempted refuelling operation.

Referring now to Figure 4 an alternative embodiment is shown. In this embodiment the body 115 carries a segmented locking member 125 comprising two diametrically opposed arcuate segments 125a, 125b each having the same general configuration as the locking member 25 shown in Figures 1 to 3.

An obstruction member 130 is pivotally connected to the body 115 at a pivot point 131 midway between two adjacent ends of the segments 125a, 125b. The obstructing member 130 is therefore supported on two diametrically opposed feet 128a, 128b.

Use of the refuelling aid 110 is substantially the same as that described in relation to Figure 3C to 3F except that a nozzle (not shown) must engage both arcuate sections 125a, 125b simultaneously in order to release both feet 128a, 128b from under the obstruction member 130 and allow continued insertion. This means that the locking member could not be overcome by positioning a nozzle slightly off- centre or at an angle.

Referring now to Figures 5A and SB there is shown a refuelling aid 210 according to an alternative embodiment. In this embodiment no body is provided but rather a single toroidal locking member 225 is provided. The locking member 225 has the same general configuration as the locking member described in relation to Figures 1 to 3 in that it comprises a roller part 226 and a base part 227 having a foot 228 which locks an obstruction member 230 in the position shown in Figure 5A. In this embodiment the locking member base 227 is formed from an elastic material which can be stretched to increase its circumference and therefore its internal bore by a fuel nozzle. If the nozzle diameter exceeds a diameter which can force the locking member 225 outwardly by a distance sufficient to disengage the foot 228 from under the obstruction member 230 to the position shown in Figure 5B then the obstruction member 230 becomes movable to the unobstructing position. In this embodiment the obstruction member 230 is carried on a flexible pivot arm 232 which is attached for example to the sidewall of a filler neck (not shown) to support the obstruction member 230 and allow it to pivot downwardly once it has been released by the locking member 225.

Referring now to Figure 6 there is shown an alternative embodiment in which an additional size restrictor is provided. The refuelling aid 310 is generally the same as the device 10 described in relation to Figure 4. However, in this embodiment the body 315 is dimensioned at its upper lace 316 to a restricting diameter d3 by a restrictor ring 317 so that only nozzles having a diameter less than a predetermined threshold can be inserted into the aid 10, at which point it will then be subject to the further dimension requirements imposed by the locking member 325.

Therefore only nozzles having a diameter greater than the threshold d defined by the locking member and less than the threshold d3 defined by the ring 317 can successfully pass through the aid and force the locking member outwardly to disengage it from the obstruction member so that continued insertion can be accomplished.

Referring now to Figure 7 a diesel filling arrangement is shown. A fuel tank 50 has an aperture 51 from which extends a filler neck 52 which terminates with a filling aperture 53. The apertures 51, 53 and filler neck 52 define a cylindrical passageway along which an aid according to the present invention could be situated. The aid could, for example, be situated at position A in the fuel tank immediately downstream of the aperture 53, within the filler neck 52 at position B or immediately downstream of the filling aperture 51 at position C. For this purpose the aid may be provided with attachment means to allow it to be attached within the diesel filling arrangement. The attachment means may be such that the aid would not become dislodged with repeated insertion and removal of nozzles and could comprise, for example, a clip or clamp.

Referring now to Figure 8 there is shown a figure filler neck 452 incorporating a refuelling aid 410 according to the present invention. The refuelling aid 410 is generally as shown in Figures 5A and SB. The aid 410 is accommodated within the filler neck 453 by virtue of a circumferential groove 454 in the filler neck 453.

The groove 454 is such that the locking ring 425 is supported in its locked position but has sufficient clearance to expand to its unlocked position when a nozzle is inserted. The pivot member 432 is connected to the interior wall of the filler neck 453.

Such a refuelling aid could therefore be formed as part of the filler neck at the point of manufacture and integrated into a new fuelling arrangement.

Referring now to Figures 9A to 9E there is shown a device 510 for preventing or at least inhibiting the misfuelling of a diesel automobile.

The device 510 comprises a toroidal body 515 comprising spaced outer and inner side hoops 580, 581 connected by top and bottom end plates 582, 583.

Three mounting arrangements 560 are provided comprising three pairs of flexible flaps 56 Ia, 561b which project radially inwardly from the outer hoop 580 into the cavity between the hoops 580, 581. The flaps 56 Ia, 561b approach each other but define a gap 562 between their free ends. Two mounting lugs 563a, 563b extend radially inwardly from the ends of respective flaps 561a, 561b either side of the gap 562. The lugs 563a, 563b serve as a mounting point for a wheel 564 which is rotatably mounted between the lugs 563a, 563b by an axle pin 565 which extends through the lugs 563a, 563b and the wheel 564. The wheel 564 extends into the gap 562.

The three mounting arrangements 560 are equally spaced around the circumference of the hoop 580. The mounting lugs 563a, 563b and the wheels 564 protrude into the opening defined by the toroidal top and bottom plates 582, 583 through U- shape windows 584 in the inner hoop 581.

An obstruction member in the form of flap 530 is positioned so as to fill the circular opening defined by the bottom plate 583. The flap 530 is connected to the bottom plate 583 by a pivot arm 532 which extends from the centre of the flap 530 to the inner periphery of the bottom plate 583. The pivot arm 532 includes a resilient hinging section 533 which allows the arm 532 to pivot by acting as a living hinge. The resilience of the material of the pivot arm 532 acts to bias the obstruction flap 530 to the position shown in the drawings in which it obstructs the opening in the bottom plate 583.

The obstruction flap 530 is shown locked in position by virtue of the engagement of its periphery by arcuate blocking elements 528 which depend from the lugs 563a, 563b. The locking elements 528a are held in the radially inward locking system by virtue of the flaps 561a, 561b which act as springs to bias the lugs 563a, 563b and hence the wheel 564 inwardly. The locking elements 528a can be moved radially outwardly if a fuel nozzle engages the wheels 564 as it is inserted so as to push the wheels 564 radially outwardly against the biasing action of the flaps 561a, 561b so as to release the locking elements 528 from under the obstruction flap 530.

Referring now to Figure JO, the device 510 of Figures 9A to 9E is shown in use.

The device will be fitted at some point in the fl.ielling arrangement of a diesel automobile such as in the filler neck (not shown) using any suitable attachment means such as a clip or clamp. A filling nozzle 570 is presented to the device 510 and could result in the scenarios explained further in Figures 1 IA to 1 iF.

Referring first to Figures 1 IA and 1 lB a nozzle 535 which supplies unleaded petrol is presented to the device 510. The diameter of the nozzle 535 is insufficient to engage the wheels 564 (only one is shown).

In Figure 1 lB the nozzle is shown pushed against the obstruction flap 530 without having first moved the locking elements 528 radially outwardly and thus the periphery of the obstruction flap 530 is still engaged by the locking elements 528.

Accordingly the nozzle 535 cannot pass the obstruction flap 530 and cannot progress further into the refuelling arrangement.

Referring now to Figure 1 1C a diesel nozzle 536 is shown presented to the device 510 and is of greater diameter then the notional opening defined by the wheels 564. Accordingly, as shown in Figure 1 ID, as the nozzle 536 is inserted it engages the wheels 564 and gradually forces them outwardly against the biasing action of the flaps 56 Ia, 561b (not shown). The nozzle 536 rolls down the outer surface of the wheels 564, which rotate as they move outwardly. Consequently the locking elements 528 are moved radially outwardly so that by the time the nozzle 536 reaches the obstruction flap 530 the locking elements 528 have cleared from under the obstruction flap 530. As the nozzle 536 is further inserted it can now push against the flap 530 and open it against the resilient action of the pivot arm 532.

When the nozzle 536 is withdrawn the resilient action of the pivot arm 532 pushes the obstruction flap 530 back to its obstruction position shown in Figure 1OF.

Further withdrawal of the nozzle 536 now allows the wheels 564 to be pushed back radially inwardly under the action of the flaps 561a, 561b so that the locking elements 528 re-engage under the obstruction flap 530 to reset the device to the position shown in Figure I I C. Referring now to Figures 1 2A and I 2B there is shown part of a device according to an alternative embodiment. The obstructing arrangement shown in Figures 12A and 12B is similar to that shown in Figures 9A to 9E in that a locking element 628 can engage under the periphery of an obstruction flap 630 to prevent its downward pivoting motion under the control of a pivot arm 632. The locking element 628 is supported by a pair of mounting lugs 663 (only one is shown) which supports an elliptical roller element 664. The roller element 664 is fixed in its position between the lugs 663.

The locking arrangement provided by the roller 626, the lugs 663 and the locking element 628 is resiliently biased to the radially inward position shown in Figure 12A by any convenient means such as the spring arrangement shown in Figures 9A to 9E or sonic form of resilient material such as foam or rubber.

En use the roller 664 does not necessarily need to rotate; it could, for example, be carried directly by spring flaps or resilient material could be used because there is no issue preventing it from spinning.

In use the roller 626 acts in the same way as the wheel 526 shown in Figures 9A to 9E except that it effects greater radial movement. The curved surface of the roller 664 serves as a convexly curved engagement surface which a nozzle can progressively engage and slide down in its linear path so as to force the locking arrangement radially outwardly to the position shown in Figure 12B. The roller 664 therefore acts as a cam surface to convert the axial movement of a nozzle into radial movement of a locking element to disengage it from an obstruction flap.

Claims (22)

1. A vehicle refuelling aid comprising: a locking member moveable from a locked position to an unlocked position; an obstruction member moveable from an obstructing position in which it prevents, in use, the passage of a fuel nozzle, to an unobstructing position in which a fuel nozzle can pass into a fuel tank; in which the locking member is operable to lock the obstruction member in the obstructing position when in its locked position and to release the obstruction member when in its unlocked position; wherein the locking member is moveable to the unlocked position only by a fuel nozzle having a diameter which exceeds a predetermined threshold such that fuel nozzles not exceeding the threshold are obstructed by the obstruction member.

2. An aid as claimed in Claim 1, in which the predetermined diameter threshold is set as the diameter of a diesel fuel nozzle such that unleaded petrol fuel nozzles are obstructed.

3. An aid as claimed in Claim 1 or Claim 2, further comprising a restrictor element which defines an upper fuel nozzle diameter threshold.

4. An aid as claimed in Claim 3, in which the upper threshold is set to exclude a lead replacement petrol nozzle.

5. An aid as claimed in any preceding Claim, in which the aid is substantially toroidal.

6. An aid as claimed in any preceding Claim, in which the locking member is biased towards the locked position.

7. An aid as claimed in any preceding Claim, in which the obstruction member is biased towards the obstructing portion.

8. An aid as claimed in any preceding Claim, in which the obstruction member comprises a flap.

9. An aid as claimed in any preceding Claim, in which the locking member comprises an engagement surface which is engageable by a fuel nozzle exceeding the predetermined threshold to move the locking member to the unlocked position.

10. An aid as claimed in Claim 9, in which the engagement surface of the locking member comprises a curved surface.

11. An aid as claimed in Claim 9 or Claim 10, in which the engagement surface comprises a roller.

12. An aid as claimed in any preceding Claim, further comprising alarm means for indicating if the obstruction member is moved without the locking member having first been moved to the unlocked position.

13. An aid as claimed in any preceding Claim, comprising attachment means for enabling it to be attached within a fuel tank filler neck.

14. An aid as claimed in any preceding Claim, in which the aid is adapted to fit within a fuel tank.

15. A fuel tank filler neck having an aid as claimed in any preceding Claim.

16. A filler neck as claimed in Claim 15, in which the aid is provided as an integral part of the neck.

17. A filler neck as claimed in Claim 15, in which the aid is provided as a separate element which can be selectively added to the neck.

18. A vehicle fitted with an aid as claimed in any of Claims ito 14.

19. A fuel tank safety device providing a first gate and a second gate, the first gate being adapted to hold the second gate in an obstructing position which prevents the passage of a fuel nozzle into a fuel tank, the first gate being moveable to a release position in which the second gate can be moved so as not to obstruct the passage of a fuel nozzle, the first gate being moveable only by a fuel nozzle having a diameter in excess of a predetermined threshold.

20. A retrofittable safety device for a diesel refuelling arrangement, the device comprising means for preventing the passage of an unleaded fuel nozzle into a diesel fuel tank which can be overcome by a diesel fuel nozzle to allow it to pass into the fuel tank.

21. A vehicle refuelling aid substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

22. A fuel tank filler neck substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.