Title:
FUEL FILLER CAP
Kind Code:
A1


Abstract:
A fuel filler cap is provided with a nozzle engagement that can engage with the nozzle of a fuel pump, enabling it to be unscrewed by turning the fuel pump nozzle. The nozzle engagement structure is designed so that it can only engage with a particular size of fuel pump nozzle, resulting in a fuel filler cap that cannot be removed with a fuel pump nozzle of a different size and goes some way toward preventing the misfuelling of cars equipped with the fuel filler cap. A second fuel filler cap is provided with a lid that may be freely rotated on the body. The cap may be activated by engaging an appropriate nozzle with the nozzle engagement means, causing the lid to become firmly attached to the cap and therefore operable for unscrewing the cap.



Inventors:
Brown, Barry Colin (Surrey, GB)
Application Number:
12/737248
Publication Date:
06/16/2011
Filing Date:
07/13/2009
Primary Class:
Other Classes:
220/212
International Classes:
B65D51/00
View Patent Images:
Related US Applications:
20080277398SEAM-WELDED 36% NI-FE ALLOY STRUCTURES AND METHODS OF MAKING AND USING SAMENovember, 2008Wilson
20100038273Sleeve, system and/or method for concealing a surface of a containerFebruary, 2010Johnson
20030150857Meal boxAugust, 2003Tsai
20080105684Latchable Lid AssembliesMay, 2008Lindsay
20090236337Transport container system for goods, especially for fruit and vegetablesSeptember, 2009Orgeldinger
20040149761Garbage receptacleAugust, 2004Smith
20080173658DEVICE FOR REMOVING DIRTY SHOE COVERSJuly, 2008Ronning
20040134922Baking pan with flip down wall panels and methodJuly, 2004Camhi et al.
20030116576Reusable sleeve for beverage containersJune, 2003Lang-boecker
20070095825Foldable-type storage boxMay, 2007Tsao
20080128412Knockdown storage vesselJune, 2008Dovey et al.



Primary Examiner:
MAUST, TIMOTHY LEWIS
Attorney, Agent or Firm:
STETINA BRUNDA GARRED & BRUCKER (75 ENTERPRISE, SUITE 250, ALISO VIEJO, CA, 92656, US)
Claims:
1. A fuel filler cap comprising: a body for fitting in a fuel filling aperture; a handle rotatably coupled to the body; coupling means for selectively coupling the handle to the body for rotating the body by rotating the lid; and a trigger for activating the coupling means.

2. A fuel filler cap according to claim 1, further comprising nozzle discrimination means for discriminating between nozzles having different properties, wherein the trigger is associated with the nozzle discrimination means for being activated by an appropriate nozzle.

3. A fuel filler cap according to claim 2, wherein the nozzle discrimination means comprises a circular channel having appropriate dimensions for receiving a nozzle, and the trigger is located in the bottom of the channel for being activated by a nozzle entering the channel.

4. A fuel filler cap according to claim 3, wherein the trigger comprises a face oriented so that it faces towards the top of the channel, the face being sloped for moving laterally under a camming action when pressed by a nozzle entering the channel.

5. A fuel filler cap according to any preceding claim 1, wherein said coupling means comprises an annular ratchet member and an arm for selectively engaging with the annular ratchet member.

6. A fuel filler cap according to claim 5, further comprising a resilient member for biasing the arm towards the annular ratchet member; wherein: the trigger is moved by a nozzle engaging with the nozzle discrimination means; the arm comprises a head for engaging with the trigger; the trigger and the head being arranged so that when they are engaged the arm is not engaged with the annular ratchet member; further wherein: the movement of the trigger caused by the nozzle causes the trigger to disengage from the arm, allowing the arm to move towards the ratchet member.

7. A method for removing a fuel filler cap from a fuel filling aperture using a fuel pump nozzle, the fuel filler cap comprising nozzle engagement means; the method comprising: engaging the fuel pump nozzle with the nozzle engagement means; and turning the fuel pump nozzle to remove the fuel filler cap.

8. (canceled)

9. (canceled)

10. (canceled)

11. (canceled)

12. (canceled)

13. (canceled)

14. (canceled)

15. (canceled)

16. (canceled)

17. (canceled)

18. (canceled)

19. (canceled)

20. (canceled)

21. (canceled)

22. (canceled)

23. (canceled)

24. (canceled)

25. (canceled)

26. (canceled)

27. (canceled)

Description:

This invention relates to fuel filling systems; more particularly fuel filler caps for vehicles and especially to a fuel filler cap for preventing the misfuelling of cars.

In recent years, common rail diesel engines have improved to the point where they offer comparable performance to petrol engines, without losing their fuel efficiency advantage over the same. As such, diesel cars have seen a surge in popularity, particularly amongst company car users. There are currently estimated to be ten million small diesel vehicles in the UK alone, with that number apparently bound to rise in the near future.

A recurring problem with diesel cars is that their drivers may mistakenly fill them with petrol, rather than diesel, when at the fuel station. With modern common rail diesel engines, misfuelling is a much more significant problem than it was with older diesel engines, as petrol does not have the same lubricating qualities as diesel and can lead to thousands of pounds of damage being caused to the fuel system, in particular the fuel injectors and pumps. Even if the driver of the car realises his mistake before starting the engine, it may be necessary to drain the fuel system, which is itself relatively expensive, and inconvenient.

Similarly, petrol cars can be misfuelled with diesel fuel, which can also cause engine damage. Petrol vehicles are misfuelled less frequently as modern unleaded petrol cars have a fuel filling aperture that is smaller than a diesel nozzle. This size discrepancy came about when catalytic converters and unleaded fuel were introduced. Catalytic converters would be damaged by the use of four-star fuel, so the size of the aperture and fuel pump nozzle for catalytic converter equipped cars and unleaded fuel were reduced to prevent the misfuelling of the vehicles. Nonetheless, misfuelling then of four-star petrol into unleaded petrol vehicles still occurred then as with the misfuelling of diesel fuel into unleaded petrol vehicles today. This may occur, for example, when a user does not properly insert a fuel pump nozzle into the fuel filling aperture, or alternatively when fuelling a vehicle using a small, portable container.

In the case of company cars and leased cars misfuelling can be more common than with privately owned cars, as the driver of such cars may be unused to filling their car with diesel and fill the car with petrol accidentally. This is a particular problem for the leasing or fleet managing company, as without prior agreement they may be liable for the mechanical cost of repairing a car if it is operated using the wrong fuel. As such, a market for a device to prevent the misfuelling of cars has come about.

The main difficulty in developing such a device is that, by UK law, unleaded petrol nozzles have a smaller diameter (21 mm) than diesel fuel nozzles (25 mm). This is useful for preventing the misfuelling of petrol vehicles, but makes it difficult to restrict the entry of an unleaded nozzle into the larger hole designed for the diesel nozzle. Furthermore, a small proportion of drivers manage to force the larger diesel fuel nozzle into the fuel filling aperture of a petrol car, meaning that the current differences in size are apparently insufficient to prevent this type of misfuelling in all cases.

Previous attempts to prevent misfuelling of cars include simple warnings, such as prominent stickers, or the electronic warning device Diesel Guard®, which emits an audible announcement to fill the car with diesel whenever the fuel filler cover is opened. However, a sticker can disfigure the looks of a car if stuck to the outside, and a car that audibly demands diesel at the filling station can be embarrassing. Furthermore, both of these devices are warnings and as such do not actually prevent the misfuelling—stickers can come off a car, and the batteries in an electronic device can be exhausted, rendering either device useless. As such, there is a need for a device that actually prevents filling a vehicle with the wrong fuel.

According to a first aspect of the invention there is provided a fuel filler cap comprising a body for fitting in a fuel filling aperture; a handle rotatably coupled to the body; coupling means for selectively coupling the handle to the body for rotating the body by rotating the lid; and a trigger for activating the coupling means.

Preferably, the fuel filler cap comprises nozzle discrimination means for discriminating between nozzles having different properties, wherein the trigger is associated with the nozzle discrimination means for being activated by an appropriate nozzle. This allows the handle to be firmly coupled to the body via the coupling means when an appropriate nozzle activates the trigger associated with the nozzle discrimination means.

Preferably, the nozzle discrimination means comprises a circular channel having appropriate dimensions for receiving a nozzle, and the trigger is located in the bottom of the channel for being activated by a nozzle entering the channel. This means that only a nozzle of appropriate dimensions can reach the trigger.

Preferably, the trigger comprises a face oriented so that it faces towards the top of the channel, the face being sloped for moving laterally under a camming action when pressed by a nozzle entering the channel. This provides a simple and robust activation of the trigger that can be used in activating the coupling means.

Preferably, said coupling means comprises an annular ratchet member and an arm for selectively engaging with the annular ratchet member. This provides a reliable mechanism for selectively coupling the handle to the body.

Preferably, the cap further comprises a resilient member for biasing the arm towards the annular ratchet member; wherein: the trigger is moved by a nozzle engaging with the nozzle discrimination means; the arm comprises a head for engaging with the trigger; the trigger and the head being arranged so that when they are engaged the arm is not engaged with the annular ratchet member; further wherein: the movement of the trigger caused by the nozzle causes the trigger to disengage from the arm, allowing the arm to move towards the ratchet member.

According to a second aspect of the invention there is provided a fuel filler cap, comprising nozzle engagement means for engaging with a fuel pump nozzle, the fuel pump nozzle including a sensing port.

Preferably, a torque applied to the fuel pump nozzle, when engaged to the nozzle engagement means, is transferred to the fuel filler cap through the nozzle engagement means. This results in a fuel filler cap that can be unscrewed by turning the fuel pump nozzle engaged with it.

Preferably, the nozzle engagement means further comprises sensing port engagement means for engaging with the sensing port of the fuel pump nozzle, such that the torque transferred from the fuel pump nozzle to the fuel filler cap is transferred through the sensing port and sensing port engagement means. This provides a simple way to transfer torque from a UK standard fuel pump nozzle to the fuel filler cap.

Advantageously, the fuel filler cap further comprises a threaded section for screwing into a fuel filling receptacle, the screwing motion being around an axis of rotation; wherein the nozzle engagement means comprises a head extending substantially along the axis of rotation, distal to the threaded section, for fitting inside the fuel pump nozzle.

Optionally, the head is a substantially cylindrical projection from the fuel filler cap having an axis that generally coincides with the axis of rotation. Such a head lacks the exposed edges of an annular head that may be damaged by a mis-aligned fuel pump nozzle.

Optionally, the head is a substantially annular projection from the fuel filler cap having an axis that generally coincides with the axis of rotation. Such a head is lighter than a cylindrical head.

Advantageously, the sensing port engagement means comprises one or more indentations in the axially directed sides of the head for accommodating the sensing port and engaging with the side of the sensing port when the fuel pump nozzle is turned. This provides a simple mechanism for engaging the sensing port and transferring the torque.

Optionally, the sensing port engagement means comprises one or more interruptions in the axially directed sides of the head for accommodating the sensing port and engaging with the side of the sensing port when the fuel pump nozzle is turned. This is an alternative mechanism for engaging the sensing port and transferring the torque.

Optionally, the sensing port engagement means further comprises a post for fitting inside the sensing port of the fuel pump nozzle.

Alternatively, the head may comprise two or more resiliently mounted members, such that at least one member is depressed on engaging with a fuel pump nozzle for creating sensing port engagement means for accommodating the sensing port and engaging with the side of the sensing port when the fuel pump nozzle is turned. This provides a head that dynamically forms sensing port engagement means when engaged with the fuel pump nozzle.

Alternatively, the head and sensing port engagement means may comprise an elongate projection, the edges of the projection being adapted for engaging with the side of the sensing port when the fuel pump nozzle is turned. This is a simple and lightweight engagement structure with a large arc through which it can be first engaged with a fuel pump nozzle.

Preferably, the head is located in a recess in the fuel filler cap such that the head and fuel filler cap define a substantially axial recess into the fuel filler cap for accepting the fuel pump nozzle. This means that the head is not exposed and is less likely to be damaged.

Preferably, the head is mounted on ratchet means such that when engaged to the fuel pump nozzle, the fuel pump nozzle does not need to turn through a full circle in order to turn the fuel filler cap.

Preferably, the fuel filler cap further comprises ratchet means oriented to provide purchase in one direction for screwing the cap into a fuel filling receptacle. This means that the fuel filler cap can be screwed into the fuel filling receptacle without the fuel pump nozzle after fuelling.

Optionally, the ratchet means comprise two or more exposed handles for turning by hand. This provides a simple and robust mechanism to screw the fuel cap into the fuel filling receptacle.

Optionally, the fuel filler cap further comprises an exposed cover that covers and is complementary to the ratchet means for providing a fuel filler cap that can be screwed by hand into the fuel filling receptacle. Such an exposed cover makes it harder to unscrew the fuel filler cap by hand, as it does not provide purchase in such a direction.

According to a third aspect of the invention, there is provided a nozzle engagement structure for attaching to a fuel filler cap comprising the nozzle engagement structure of any one of claims 1 to 13.

According to a fourth aspect of the invention, there is provided a key for engaging with a fuel filler cap, the key having substantially the same cross section as a fuel pump nozzle.

According to a fifth aspect of the invention, there is provided a method for removing a fuel filler cap from a fuel filling receptacle using a fuel pump nozzle, the fuel filler cap comprising nozzle engagement means; the method comprising engaging the fuel pump nozzle with the nozzle engagement means; and turning the fuel pump nozzle to remove the fuel filler cap.

Embodiments of the invention will now be described, by way of example, with reference to the drawings in which:

FIG. 1 is a schematic cross section of a fuel pump nozzle;

FIG. 2 is a schematic perspective view of a fuel filler cap having a ring-shaped nozzle engagement structure in accordance with the invention;

FIG. 3 is a schematic perspective view of a fuel filler cap having a cap body shaped to allow turning in only one direction in accordance with the invention;

FIG. 4 is a schematic perspective view of a fuel filler cap having a recessed nozzle engagement structure in accordance with the invention;

FIG. 5 is a schematic perspective view of a fuel filler cap having a recessed nozzle engagement structure having multiple sensing port engagement holes in accordance with the invention;

FIG. 6 is a schematic perspective view of a fuel filler cap having a solid, protruding nozzle engagement structure in accordance with the invention;

FIG. 7 is a schematic perspective view of a fuel filler cap having a cross-shaped nozzle engagement structure in accordance with the invention;

FIG. 8 is a schematic perspective view of a fuel filler cap having an interrupted ring nozzle engagement structure with a further protrusion for fitting inside the sensing port;

FIG. 9 is a schematic perspective view of a fuel filler cap having a spring-mounted segmented nozzle engagement structure;

FIG. 10 is a schematic perspective view of a fuel filler cap having a “single blade” nozzle engagement structure;

FIG. 11 is a perspective view of a fuel cap according to an embodiment of the invention;

FIG. 12 is a plan view of the fuel cap shown in FIG. 11 with its lid removed, exposing the internal mechanism;

FIG. 13 is a plan view of an arm according to an embodiment of the invention;

FIG. 14 is a plan view of a locking ring according to an embodiment of the invention;

FIG. 15 is an exploded perspective view of a button, arm and locking ring according to an embodiment of the invention;

FIG. 16 is a plan view of the fuel cap as shown in FIG. 12 with its mechanism in the unlocked state; and

FIG. 17 is a plan view of the fuel cap as shown in FIG. 16 with the mechanism activated.

The embodiments described below are explained in relation to a removable fuel filler cap for cars. The caps described are adapted to prevent the misfuelling of diesel vehicles with unleaded petrol. However, the principles described may readily be adapted for use in other filler caps on other vehicles, or any other device that needs fuel such as a generator, a fuelled lawn mower, chainsaw etc. The principles described may also be readily adapted for use in fuel filler caps adapted to prevent the misfuelling of, for example, unleaded petrol powered vehicles. The present embodiments are described based on the sizes and assignment of sizes of fuel pump nozzles as correct at the time of filing. The principles described may be readily adapted should the sizes of such nozzles change. Furthermore, in the event of other fuels with different nozzle configurations or sizes being used, the principles described may be adapted for use with them. The principles described are based on engagement with a fuel pump nozzle having certain dimensions and not limited to engaging diesel fuel nozzles and rejecting unleaded petrol nozzles, or engaging unleaded petrol nozzles and rejecting diesel nozzles.

In this document, the term nozzle is used to describe the nozzle of a fuel pump such as might be found at a petrol station, motorway service station or otherwise.

In normal use, to fill a car's fuel tank, the nozzle is inserted into a fuel filling aperture which comprises a channel that leads to the fuel tank. This fuel filling aperture is normally closed with a fuel filler cap which screws into the fuel filling aperture. This screwing action may require a number of turns of the fuel filler cap, or alternatively only an incomplete turn. The fuel filler cap may further be covered by a fuel filler cover that may serve to disguise the fuel filler aperture, fuel filler cap and associated indentation into the body of the car. The term nozzle engagement structure is used in this document to refer to a structure that can engage with a nozzle.

The shape of fuel pump nozzles is standardised by legislation in the UK and elsewhere. FIG. 1 shows a schematic cross section of a typical fuel pump nozzle 2. The nozzle 2 comprises a nozzle body 4 that encloses a nozzle channel 6. Nozzle body 4 has an outer diameter of 21 mm in the case of a nozzle for unleaded petrol, and 25 mm in the case of a nozzle for diesel or leaded petrol. These values are the ideal values, and there may of course be some small variation between nozzles. The inner diameter of the nozzle in these cases is approximately 16.5 mm and 19.5 mm respectively.

This difference between those sizes of the unleaded petrol nozzle and diesel nozzle provides a way of differentiating between the two and was originally introduced to prevent diesel fuel being introduced into petrol vehicles equipped with catalytic converters. Although a fuel filling aperture large enough for a diesel nozzle cannot easily exclude the smaller unleaded petrol nozzle, a structure can be designed such that it can only engage a diesel nozzle and not an unleaded petrol nozzle. Such a structure can be achieved by having a head that fits inside nozzle channel 6 of a diesel nozzle, but is too large to fit inside nozzle channel 6 of an unleaded petrol nozzle. This structure may be a singular, large protrusion, or be a head consisting of a plurality of smaller members that cannot all fit inside an unleaded petrol nozzle simultaneously. Similarly, a nozzle engagement structure may be designed for engaging with an unleaded petrol nozzle, which would be too small to engage properly with a diesel nozzle. However, such a head would still fit inside a diesel nozzle, so it may be preferable to locate the head in a recess that is too small to permit the entry of a diesel nozzle so that the head is not able to engage with the nozzle.

However, such a structure, whether the head comprises a single member or a plurality thereof, is not suitable for use in a fuel filling aperture as by design it protrudes into fuel nozzle channel 6 and hence reduces the area through which fuel can be pumped. Furthermore, it would be complicated to design a suitable structure for retrofitting into vehicles as fuel filling apertures vary greatly between car models and manufacturers.

Fuel pump nozzle 2 further comprises a sensing port 8, again by legislation. It is this port that is used to detect when the fuel tank is full, and hence to stop pumping fuel. This is achieved by applying a vacuum to sensing port 8; when fuel travels into the sensing port the pump is cut off in a manner that is not material to the invention under discussion and hence is not described here. Sensing port 8 comprises a sensing port body 10 that encloses a sensing port channel 12. As shown in FIG. 1, sensing port channel 12 is partly defined by sensing port body 10, and partly by nozzle body 4, leaving the exterior of nozzle body 4 unaffected by the presence of sensing port 8. In a diesel fuel nozzle, sensing port 8 has an outer diameter of approximately 7.5 mm. This can also be described as a radial protuberance into nozzle channel 6 of approximately 5 mm from the inner edge of nozzle body 4, and a circumferential extension along the outside of nozzle body 4 of approximately 10 mm. In unleaded petrol nozzles, the outer diameter and protuberance into nozzle channel 6 are typically similar. In this case, the circumferential extension along the outside of nozzle body 4 is approximately 8.5 mm.

It is this sensing port 8 that allows the fuel filler cap shown in FIGS. 2 to 10 to work. Sensing port 8 is a protuberance into the nozzle channel 6, which provides a point that can engage with the previously mentioned head designed for the fuel pump nozzle 2. This engagement allows the item comprising the structure to be turned by turning fuel pump nozzle 2. As such, by incorporating such a structure (be it a single head or head comprising a plurality of members) into a fuel filler cap, a diesel nozzle can be used to unscrew the fuel filler cap where an unleaded petrol nozzle could not. This is a similar arrangement to that of a bolt and spanner. The fuel pump nozzle 2 with its sensing port 8, which constitutes a structure for transferring torque, may be likened to a spanner for engaging with the head; the head which is complementary to the fuel pump nozzle 2 transfers torque to the rest of the fuel filler cap in a similar manner as the head of a bolt.

Similarly, a nozzle engagement structure for engaging with an unleaded petrol nozzle can be designed that fits inside a petrol nozzle, but is too small to engage with the sensing port 8 of a diesel nozzle. Alternatively, the nozzle engagement structure may be in a recess in a fuel filler cap, the recess having a diameter that prevents the entry of a diesel nozzle.

Referring now to FIG. 2, a fuel filler cap 14 is provided according to a first embodiment of the invention. Fuel filler cap 14 comprises a threaded section 16 for fitting to the fuel filler aperture of a car in the usual way. This threaded section may comprise any number of threads depending on the application and the fuel filling aperture it is designed to be complementary to. Furthermore, in the case of a fuel filler cap that requires only a fraction of a turn to screw into a fuel filling aperture, the threaded section may comprise only short inclined projections or indentations that serve the function of a thread. Attached to the threaded section 16 is cap body 18. This may be provided with ridges or otherwise in order to facilitate gripping it for removal or replacement. Threaded section 16 and cap body 18 may be separate, removably joined components, or may be separate sections of the same component. The distinction between them may not be as clear as is shown in FIG. 2.

Fuel filler cap 14 further comprises a nozzle engagement structure 20. In this embodiment, nozzle engagement structure or head 20 protrudes from cap body 18. It is in the form of a protruding ring or annulus having an interruption for engaging with the sensing port of a nozzle. For engaging with a diesel fuel pump nozzle, the outer diameter of the ring is between 17.5 mm and 19.5 mm, and preferably between 18 mm and 19 mm, and more preferably 18.5 mm. Because of its size, nozzle engagement structure 20 is too large to fit inside the nozzle of an unleaded petrol fuel pump, and as such cannot engage with it. However, when the sensing port of a diesel nozzle is aligned with the interruption of nozzle engagement structure 20, the nozzle fits over engagement structure 20 and can then be used to turn fuel filler cap 14, and so can be used to unscrew the nozzle. In order to properly accommodate the sensing port of a diesel nozzle, the interruption in nozzle engagement structure 20 is at least 7.5 mm in terms of the circumferential gap (measured at the outer circumference of engagement structure 20), assuming an outer diameter of engagement structure 20 of 18.5 mm.

In the case that nozzle engagement structure is for engaging with an unleaded petrol nozzle, it is not likely that an interrupted ring alone will be sufficient to exclude a diesel nozzle—any ring that fits inside a petrol nozzle will also fit inside a diesel nozzle and may, to some extent, permit the fuel filler cap 14 to be turned by the nozzle. As such, it is preferable to locate such a ring in a recess, as described above and in more detail below. For engaging with an unleaded petrol fuel pump nozzle, the outer diameter of the ring is between 12 mm and 16.5 mm, and preferably between 14 mm and 16.5 mm, and more preferably 15.5 mm. Exceptionally, a ring with a diameter of less than 12 mm may work, but it will not engage the sensing port unless it is somehow forced towards it and will thus have a more complicated operation. In order to accommodate the sensing port of an unleaded petrol nozzle, the interruption in the ring is preferably at least 8 mm, measured as above and assuming an outer diameter of the ring of 15.5 mm.

Nozzle engagement structure 20 provides a simple test for whether the appropriate fuel pump nozzle has been selected. Although there is nothing stopping somebody unscrewing the fuel filler cap 14 by gripping cap body 18, unscrewing (or starting to unscrew) the fuel filler cap 14 using the fuel pump nozzle is a simple behaviour to learn. Alternatively, fuel filler cap 14 may be designed such that the face of cap body 18 is flush with the fuel filler aperture when secure, meaning that a pump nozzle must be used at least to start unscrewing the fuel filler cap 14. A disadvantage of this approach, however, is that a fuel pump nozzle must be used to replace the fuel filler cap 14 as well as remove it.

In order to provide drainage for fuel that might be present in the fuel pump nozzle when it is used to unscrew or replace fuel filler cap 14, the cap 14 may further comprise one or more drainage hole 22 to allow fuel to flow away. This might lead into the fuel filler aperture of the car when the fuel filler cap 14 is in place, or might divert elsewhere. In the former case it is likely that a valve would be required to prevent the escape of fuel vapour. It should be noted at this point that, with nozzle engagement structure 20 providing a mechanism for turning fuel filler cap 14, the cap body 18 of fuel filler cap 14 is no longer strictly necessary, and may in some minimal cases be completely absent. However, for most practical cases it will be maintained.

Referring now to FIG. 3, a fuel filler cap 14 is provided according to a second embodiment of the invention. As above, fuel filler cap 14 comprises a threaded section 16, a cap body 18 and a nozzle engagement structure 20. In this embodiment, fuel filler cap 14 further comprises a pair of sloped handles 24. These handles 24 have a similar shape and function to some security screws, in that the handles 24 are designed such that fuel filler cap 14 can be easily screwed into a car's fuel filling aperture by hand, but they do not provide suitable purchase for removing fuel filler cap 14 by hand. This provides a cap that, in the absence of ridging etc. on cap body 18, encourages the use of a fuel pump nozzle to remove fuel filler cap 14, but then provides a simple way of replacing fuel filler cap 14 by hand. FIG. 3 shows handles 24 as being located on the face of fuel filler cap 14, as may be suitable for use in a fuel filler system wherein the face of cap body 18 is flush with the fuel filler aperture or car body when secure. Alternatively, sloped handles 24 may be present on the circumference of cap body 18. Such an arrangement would likely be incompatible with the flush-fitting cap body 18 described, however.

Sloped handles 24 have a structure and function similar to that of a ratchet. They have an upright side that, in this case, has a face pointing in a counter-clockwise direction (when looking at the face of the fuel filler cap 14) for receiving a clockwise force. The sloped side (which points in a clockwise direction from the apex of the handle 24) forms a more acute angle at its far end and is more difficult to apply force against. In different embodiments of the invention, there may be fewer or more than two handles 24. Furthermore, the ratchet-like handles 24 may be hidden by a second cap that covers them and is equipped with complimentary ratchets on the inside. This second cap would then replicate the feature of being turnable by hand to screw in fuel filler cap 14, but would not provide purchase for unscrewing fuel filler cap 14 by hand.

In a third embodiment of the invention (not pictured), nozzle engagement structure 20 may be equipped with (or mounted on) a ratchet, or similar ratcheting means. This provides a method of removing fuel filler cap 14 from the car without having to perform a full rotation of the fuel pump nozzle, which can be awkward when the fuel pump nozzle is connected to a bulky hose.

Referring now to FIG. 4, a fuel filler cap 14 is provided according to a fourth embodiment of the invention. As above, fuel filler cap 14 comprises a threaded section 16 and a cap body 18. In this embodiment, nozzle engagement structure 26 is recessed into the cap body 18 (and may also extend into threaded section 16 if necessary). Nozzle engagement structure 26, in conjunction with cap body 18, defines a recessed circular channel for fitting the nozzle body of a fuel pump nozzle. There is further a sensing port engagement hole 28, being an indentation into the head 26 which fits into the nozzle channel of a fuel pump nozzle, for engaging with the sensing port of a fuel pump nozzle. This embodiment provides a mechanism allowing similar methods of removing fuel filler cap 14, i.e. by using a fuel pump nozzle, without having a protruding nozzle engagement structure that is easy to damage and might interfere with the closing of the fuel filler cover. Furthermore, this can provide a simple fuel filler cap that can engage with an unleaded petrol fuel pump nozzle and not a diesel fuel pump nozzle, as the circular channel can be made too small for fitting a diesel nozzle. Slotting the nozzle into a hole may also be easier for some people than fitting it over a protrusion. To facilitate insertion of the nozzle, the circular recess may have a chamfered or tapered entry area. This chamfering or tapering may also be useful in the case of a protruding nozzle engagement structure.

In this embodiment, nozzle engagement structure 26 has a similar outer diameter to that described in the first embodiment, depending on what nozzle it is designed to engage with. The channel that fits the nozzle body has a thickness of between 2.3 mm and 5 mm, and preferably between 2.5 mm and 4 mm, and more preferably 3 mm. This preferred value should be sufficient to fit either an unleaded petrol nozzle or diesel nozzle. Sensing port engagement hole 28 has to be of a suitable size to accommodate the sensing port, and so has a depth (radial indentation away from the outer edge of the nozzle engagement structure) of at least 5 mm. Sensing port engagement hole 28 also has a circumferential extent similar to that described in the first embodiment, depending on the outer diameter of the nozzle engagement structure and the nozzle it is designed to engage with.

Referring now to FIG. 5, a fuel filler cap 14 is provided according to a fifth embodiment of the invention. The difference between this embodiment and the one pictured in FIG. 4 is that there is more than one sensing port engagement hole 28 (four are pictured, this could be any number). This results in a nozzle engagement structure 26 that can engage a fuel pump nozzle in a variety of different angles or attitudes. This was a potential problem with other embodiments which could only engage the fuel pump nozzle at one angle, as this could result in having to twist the fuel pump nozzle into a difficult angle in order to first engage with the fuel filler cap, this task being further complicated by the often heavy fuel hose.

One requirement that limits the number of sensing port engagement holes 28 that it is possible to have in a nozzle engagement structure, is that the intervening lobes between the holes must be strong enough to withstand the turning force. More particularly, the lobes that protrude between the sensing port engagement holes are used to transmit the turning torque from the fuel pump nozzle to the fuel filler cap 14, and must be large enough to withstand the force. The size that will be necessary depends on the strength of the material from which they are made.

Referring now to FIG. 6, a fuel filler cap 14 is provided according to a sixth embodiment of the invention. As with the first and second embodiments, there is a protruding nozzle engagement structure 30. Unlike the first and second embodiments, the nozzle engagement structure 30 is solid rather than hollow, giving it a stronger structure or alternatively allowing it to be made of a weaker material whilst retaining the same strength. Such a solid nozzle engagement structure 30 is also likely to be harder to damage by any “near misses” of the fuel pump nozzle on the approach. As in the fifth embodiment of the invention, nozzle engagement structure 30 can accommodate the sensing port of a fuel pump nozzle in any one of four positions, meaning that the amount by which the fuel pump nozzle needs to be twisted in order to engage with nozzle engagement structure is reduced. Such a structure also provides an alternative to the ratchet mechanism described in the third embodiment—the function can be replicated by removing and replacing the fuel pump nozzle in a different angle, allowing fuel filler cap 14 to be removed without having to turn the fuel pump nozzle through 360°. In this embodiment, nozzle engagements structure 30 has similar dimensions to those of the nozzle engagement structures of the fourth and fifth embodiments.

FIG. 7 shows a seventh embodiment of the invention with very similar structure to the sixth embodiment. In this embodiment, nozzle engagement structure 32 is not a large protruding solid that substantially fills the nozzle channel of a fuel pump nozzle, but instead a more “minimal” structure, consisting of two sheet-like members, or “blades”, in an “X” configuration. As with the sixth embodiment, this nozzle engagement structure 32 provides four locations for engaging the sensing port of a fuel pump nozzle, however the more open structure means that rather than closely following its shape the sensing port is more widely accommodated, providing a wider range of angles in which the sensing port can be fitted and thus making it easier to engage with a fuel pump nozzle. Upon turning a fuel pump nozzle engaged with nozzle engagement structure 32, the sensing port will shortly come into contact with one of the “blades” of the structure and thus allow the fuel filler cap 14 to be turned by the fuel pump nozzle.

In this embodiment, in order to exclude the possibility of an unleaded petrol fuel pump nozzle engaging with nozzle engagement structure 32, at least one of the “blades” that constitute it should be too large to fit inside an unleaded petrol fuel pump nozzle. This results in one of the blades having a length of between 17.5 mm and 19.5 mm, and preferably between 18 mm and 19 mm, and more preferably 18.5 mm (the minimum value of 17.5 mm rather than 17 mm allows for slight variations in the size of fuel pump nozzles, and prevents the possibility of an unleaded petrol fuel pump nozzle being forced into engagement). If nozzle engagement structure 32 is to engage with an unleaded petrol nozzle, the blades must obviously have a length of less than 16.5 mm, and preferably in excess of 12 mm for engaging well with the sensing port. Preferably, the blades have a length of between 14 and 16.5 mm, and more preferably 15.5 mm.

It should be noted at this point that only one blade could be used in this embodiment. Such a fuel filler cap is shown in FIG. 10. In this figure, fuel filler cap 14 comprises a single blade nozzle engagement structure 33, shown as a three-dimensional blade rather than a two-dimensional sheet as in FIG. 7. In this case, the fuel pump nozzle engaged with nozzle engagement structure 33 would normally need to be turned further before the sensing port engaged the blade and fuel filler cap 14 could begin being turned by the fuel pump nozzle. It is also possible that any number blades could be used (including odd numbers), so long as the space left between them was sufficient to fit a sensing port. In the case of an odd number of blades, the blades may extend from the centre of fuel filler cap 14 where they meet, rather than from one edge of the nozzle engagement structure to the other. Furthermore, it is possible that this nozzle engagement structure could be recessed into the cap body 18 in a similar manner to the fourth embodiment.

FIG. 8 shows an eighth embodiment of the invention, with a substantially different nozzle engagement structure, comprising two separate and different components. Fuel filler cap 14 has a nozzle engagement structure 34 that is similar to the nozzle engagement structure of the first embodiment (but is shown in FIG. 8 as having a larger interruption for clarity). Fuel filler cap 14 further comprises sensing port engagement structure 36. Unlike the hole-like structures for accommodating the sensing port of a fuel nozzle in previous embodiments, post-like sensing port engagement structure 36 is designed to fit in to the sensing port channel. This provides a different mechanism for engaging with the sensing port of a fuel pump nozzle, and for transferring torque therefrom to the fuel filler cap 14.

In order to fit inside a diesel fuel pump sensing port, sensing port engagement structure 36 has a diameter of approximately 2.5 mm. In order to fit within a diesel fuel pump nozzle and exclude an unleaded petrol fuel pump nozzle, the distance between the outermost edges of the sensing port engagement structure 36 and nozzle engagement structure 34 is between 17.5 mm and 19.5 mm, and preferably between 18 mm and 19 mm, and more preferably 18.5 mm. Furthermore, in order to exclude the possibility of an unleaded nozzle fitting over just one or the other of nozzle engagement structure 34 and sensing port engagement structure 36, nozzle engagement structure 34 preferably extends over an arc such that the widest measurement across it is at least 17 mm. If the fuel filler cap is to engage with an unleaded petrol fuel nozzle, the sensing port engagement structure has a similar diameter, and the distance between the outermost edges of the sensing port engagement structure 36 and nozzle engagement structure 34 is between 12 mm and 16.5 mm, and preferably between 14 mm and 16.5 mm, and more preferably 15.5 mm.

FIG. 9 shows a ninth embodiment of the invention. In this embodiment, fuel filler cap 14 comprises a segmented nozzle engagement structure 38, which is round and has a similar outer diameter to the first embodiment for fitting inside the nozzle channel of a fuel pump nozzle, depending on which nozzle it is to fit. The segments are shown as being pie-like slices, but other configurations of segments are also possible. Each of these segments is mounted on a spring or other resilient means, such that when a fuel nozzle is placed over nozzle engagement structure 38 the sensing port pushes down one or more of the segments. This enables the fuel nozzle to be placed over the nozzle engagement structure 38 in the normal way at any angle. After the nozzle is pushed over the nozzle engagement structure 38, upon turning the nozzle the sensing port will come into contact with the side of one of the remaining segments, which allows torque to be transferred and the nozzle to be used to turn fuel filler cap 14. This embodiment provides a nozzle engagement structure that, although more mechanically complicated than the nozzle engagement structure of previous embodiments, is extremely simple to use as it adapts to the angle at which the nozzle is engaged with it.

A potential problem of the above described embodiments could occur when trying to remove a fuel filler cap when not at a fuel pump, for example when refueling a petrol lawn mower or partially filling a car's fuel tank after it has broken down due to lack of fuel. In order to overcome this problem, a key could be produced, having a cross section at least similar to that of a nozzle for engaging the fuel filler cap when away from a fuel pump. This key could be sold separately and kept with the vehicle it fits for emergency use, or alternatively supplied with portable fuel containers.

The skilled person will appreciate that, although the above embodiments describe a whole fuel filler cap with an integrated nozzle engagement structure or head, a separate nozzle engagement structure could be marketed and sold for retrofitting to fuel filler caps. Such a separate nozzle engagement structure may take the form of a simple attachment mounted to a fuel filler cap by an adhesive, screws, nails or mechanical clips, or may require removal of part of the fuel filler cap such as the cap body and replacing it. The separate nozzle engagement structure could take any combination of the features described above, but may require more substantial modification to the base structure for some features e.g. a hole may need to be drilled into a fuel filler cap to fit a separate nozzle engagement structure similar to that illustrated in FIG. 9.

In the embodiments above, various different features are described in light of different embodiments. The skilled person will realise that the features from different embodiments can be combined in various ways to result in different fuel filler caps, e.g. having the nozzle engagement structure of the first embodiment embedded into the cap body as in the fourth embodiment, also further comprising more than one interruption for engaging the sensing port as in the fifth embodiment.

The skilled person will also realise that other structures and configurations may be used to implement the nozzle engagement structure or head. In the case of a fuel filler cap for a diesel vehicle, the fuel filler cap needs one or more structures that protrude into the nozzle channel of a fuel pump nozzle that do not fit inside an unleaded petrol nozzle but do fit inside a diesel nozzle. In the case of a fuel filler cap for an unleaded petrol vehicle, the structures that fit inside the nozzle will necessarily also fit inside a diesel nozzle, although they may not engage well with it. In order to ensure the rejection of a diesel nozzle in such a case, there needs to be a further engagement mechanism such as the recess illustrated in FIG. 4 or 5.

It is possible to construct an even more minimal embodiment than a “single blade” variant of the seventh embodiment, comprising two or more “posts” that, measured from furthest edge to furthest edge fit inside a diesel nozzle but not inside an unleaded fuel nozzle. Such an embodiment could be viewed as having the nozzle engagement structure of the first embodiment with two or more large interruptions, or having the nozzle engagement structure of the fifth embodiment in which the sensing port engagement holes have a radial depth such that they meet in the middle. However, such a “post” embodiment is not very practical, as the posts would need to be particularly strong in order to withstand the turning forces due to their small size, and it would be possible to place an unleaded petrol nozzle over only one of the posts and perhaps use the nozzle to unscrew the fuel filler cap in such a situation.

FIG. 11 shows a further fuel filler cap 14. The cap 14 has a lid 40, which is adapted by way of indentations 42 to act as a handle for the cap as a whole. The cap 14 further comprises a body 43 onto which the cap 14 is mounted. The body 43 comprises the fitting for securing the cap in a fuel filling aperture, illustrated here as a screw thread that screws the cap into the aperture on turning the cap clockwise. Alternatively, as described above, this fitting may be of the bayonet type or any other appropriate fitting. Depending on the requirements imposed by safety and reliable operation of the vehicle, the body may contain various valves to permit venting of excess pressure on one side or the other of the cap, or valves for sealing the cap in the event of an accident.

Lid 40 is rotatably coupled to the body 43 of the cap 14, such that in its rest state the lid may be freely rotated without exerting a significant force on the body, thus rendering the lid inoperable for tightening or loosening the cap in the fuel filling aperture.

The cap further comprises a recessed nozzle engagement structure 46 comprising an annular channel 45 with a radial extension 47 to accommodate the sensing port of a fuel nozzle. This nozzle engagement structure is comparable to that shown in FIG. 4.

The nozzle engagement structure in this embodiment is designed to engage with a diesel nozzle and not a petrol nozzle. The central head of the nozzle engagement structure has a diameter at its widest point that is too large to fit inside a petrol nozzle. At the base of the annular channel there is a trigger 44, which is exposed in FIG. 12. When the trigger 44 is pressed, for example by a diesel nozzle that has engaged with the nozzle engagement structure 46 and fit into the annular channel 45 in which the trigger is located, a mechanism (described below) is engaged that more firmly couples the lid 40 to the body of cap 14. The engagement of this mechanism means that the lid 40 can now be used to unscrew the cap 14, permitting access to the fuel filling aperture for fuelling the car to which cap 14 is fitted.

The apparatus described above provides a simple and user-friendly mechanism for preventing misfuelling of cars. Upon arriving at a petrol station the user need simply press the nozzle they intend to use to fuel the car into the nozzle engagement structure 46 to activate the cap so that it can be removed. If the user has selected an inappropriate nozzle, such as an unleaded petrol nozzle, they will not be able to activate the cap and thus will be unable to fill the vehicle with the incorrect fuel. After activating the cap by this simple pressing action, the user is able to remove the fuel filler cap 14 by hand, in the usual way. The mechanism that engaged the lid 40 with the cap body is arranged to disengage when a certain tightening torque is exceeded, meaning that the cap will automatically return to its rest state in which the lid 16 is disengaged from the body 43 upon being screwed back in, ready for repeat use.

The cap 14 may further comprise a lock 48 for securing the cap to prevent e.g. theft by the siphoning of fuel. This may be particularly desirable on cars in which the fuel filler cover is not automatically locked by the car. This lock may be used to prevent the opening of the cap 14 by preventing the lid 40 from engaging with the body, meaning that purchase cannot be obtained in order to remove the cap 14.

FIG. 12 shows the internal structure of cap 14. The trigger 44 is shown without the nozzle engagement structure. As will be shown more clearly in later Figures, the top of trigger 44 is sloped such that pushing a fuel nozzle into the nozzle engagement structure will tend to make trigger 44 move under a camming action laterally towards the centre of the nozzle engagement structure. The trigger is equipped with biasing means adapted to provide a resistive force to this motion and return the trigger to its original location after the nozzle is removed.

Referring now to FIGS. 12 and 13, the mechanism of the cap 14 includes an arm 50. The arm has a generally central pivot 52 having an axis approximately parallel with the axis of rotation of the lid 40. This pivot is attached to the underside of the lid 40, towards the edge of the lid. The arm is equipped with biasing means coupled to one end of the arm for pushing the other, distal end of the arm towards the outside edge of the lid 40. In the configuration shown in FIG. 12, the arm is unable to move in response to biasing force because the trigger 44 is holding the arm in place. The trigger 44 fits into a recess 55 in the head of arm 50, therefore preventing the arm from pivoting while the trigger is within the recess. When a nozzle is introduced into the nozzle engagement structure, trigger 44 is pushed away from the arm 50 and leaves the recess 55, freeing the arm to rotate around the pivot 52 in response to the biasing force. This causes a protruding finger 56 to come into contact with and engage within a ratchet track 58 that runs around the inside edge of cap 14.

Whilst the arm 50 and trigger 44 are both coupled to the lid of the cap 14, the ratchet track 58 is joined to the body 43 of the fuel filler cap. Therefore, by pressing the trigger and releasing the arm, a connection is created between the lid and the body of cap 14 allowing a torque to be transferred between the two components and activating the cap so that it can be removed by turning the lid.

It should be noted that the pressing of the trigger need not be continuous since once it has been pressed, the arm 50 no longer engages trigger 44 and will remain in place until it jumps out of engagement with the ratchet track 58 as described below.

The ratchet track 58 and finger 56 are arranged so as to prevent slipping when turning the lid clockwise, which in most vehicles is the direction one turns a fuel filler cap to tighten it. The construction of the ratchet track 58 means that when tightening the fuel filler cap, if the torque applied to the lid exceeds a certain amount then the arm 50 will jump out of contact with the ratchet track and be re-captured by the trigger 44, therefore disengaging the lid from the body of the cap. This reproduces the commonly found ratchet feature in current fuel filler caps that prevents over-tightening of the cap, as more than a certain amount of resistance to turning the body of the cap in the aperture will trigger this disengaging mechanism.

The shape of the ratchet track and arm, and the biasing forces on the arm and trigger, can be selected such that the disengagement torque required to trigger the disengagement of finger 56 and ratchet track 58 is less than the maximum torque which can be applied when unscrewing the cap without the arm slipping, therefore avoiding the situation where the ratchet track allows the cap to be screwed into a fuel filler aperture tighter than can be removed with the purchase offered by the cap.

As depicted in FIGS. 12, 13 and 14, arm 50 further comprises a locking post 60 for fitting in a locking ring 62. The locking post 60 protrudes below the arm 50 and is long enough to fit within the hole 64 of the locking ring 62, which is also situated below the arm 50. The locking ring is attached to the lock 48 of the cap. The locking ring defines a hole 64 having a wide end 66 and a narrow end 68. The locking ring 62 is depicted in FIG. 12 as being in a locked position. In this position, locking post 60 is tightly held within the narrow end 68 of the locking ring hole 64 and the arm is actually unable to pivot around pivot 52 as described above. On turning the lock anti-clockwise through a right angle, for example, using a key, the locking post 60 will be located in the wide end 66 of the locking ring hole 64, which allows the arm 50 to pivot when released by trigger 44.

Referring now also to FIG. 15, the relationships between arm 50, trigger 44 and locking ring 62 can be more clearly understood. The trigger 44 and its complementary recess 55 can be seen in relation to each other. The sloped top of trigger 44 that causes it to move to one side when pressed by a nozzle is clearly visible. The locking post 60 and locking ring hole 64 are shown in a locked relationship; with the locking post 60 being directly above the narrow end 68 of the locking ring hole 64.

Referring now also to FIG. 16, the fuel filler cap 14 is shown with the locking ring 62 in its unlocked position. The locking ring 62 has been rotated 90° anti-clockwise. The locking pin 60 is now located in the wide end 66 of the locking ring hole 64, so that when the trigger 44 is activated the arm 50 will be free to rotate around pivot 52 and engage ratchet track 58 via finger 56.

FIG. 17 shows the cap 14 in the activated state, in which the lid of the cap (not shown) is coupled to the body of the cap via arm 50 and ratchet track 58. The arm is shown rotated around the pivot 52, and finger 56 is firmly engaged with ratchet track 58. As can be seen in the figure, trigger 44 is well clear of the arm 50 and so can be released. It is worth noting at this point that the engagement of finger 56 and ratchet track 58 will not always occur unaided. In particular, since the arm is coupled to the lid, which may be freely rotated when in its rest state, the finger 56 may be directly adjacent to a protrusion in the ratchet track 58 when the arm 50 is released by trigger 44. In such a situation the arm may become stuck without fully engaging. This problem is easily mitigated by giving the cap a slight twist whilst button 44 is still depressed (otherwise, if trigger 44 is released before the twist is administered, the arm 50 may become secured again in its rest state). This twist is easily carried out using the fuel nozzle whilst it is engaged with the nozzle engagement structure.

An embodiment of a fuel filler cap has been described above, with reference to the Figures. The skilled person will realise that various modifications could be made to the embodiment within the scope of the invention. For example, the locking mechanism described, including locking ring and locking pin, may not be necessary in some vehicles. Furthermore, on a vehicle where a fuel filler cap with a locking mechanism is preferable, the locking mechanism may be implemented using any other method known to the art, for example by securing the fuel filler cap to some part of the fuel filling aperture or vehicle body.

The mechanism that couples the lid of the fuel filler cap to the body is described as being activated by a trigger that moves under a camming motion. The skilled person will realise that many alternative devices may be appropriate for triggering the mechanism contained in the fuel filler cap, including levers, switches, buttons and the like. The embodiments above are fuel-nozzle specific by virtue of an engagement structure dimensionally compatible with diesel nozzles and incompatible with unleaded petrol nozzles, the trigger being sheltered within the engagement structure so that it is pressed by a nozzle engaging with the structure.

Two biasing means are described above, related to the trigger and the arm. The skilled person will realise that these means may be implemented by a variety of devices such as springs, rubber bands or resilient plastics built into the cap as a whole. Furthermore, these biasing means may be arranged so as to work in tension or compression. The biasing means may also be coupled to other parts of the components from those described without affecting the operation of the invention. For example, the arm is described above as having a biasing means coupled to one end of the arm, distal from the finger for engaging with the ratchet track. The skilled person will realise that biasing means could alternatively be coupled to the end of the arm having the finger without materially affecting the operation of the invention.

The cap as described above has two states: a rest state and an activated state. During the rest state, the lid is rotatably coupled to the body of the cap so that it is not useful for exerting a significant torque for unscrewing the cap. When activated, the lid and body are firmly coupled such that the lid may be turned to unscrew the cap. The lid may cover the entire upper or external surface of the cap, or alternatively may be an annular or ring-shaped handle component that encircles the body of the cap on its circumference and hinders a rotating force being exerted on the body of the cap by preventing a force being applied to the circumference of the body directly.

In an alternative embodiment, the lid of the cap may be coupled to the fuel filling aperture or vehicle body in its rest state. This prevents rotation of the body by turning the lid similar to that above, although in this embodiment because the lid cannot be rotated. On activating the cap, the lid may then be decoupled from the aperture or vehicle body so that the cap may now be removed. This embodiment may be realised in a directly analogous way to that described above, with one of the mechanisms components (for example, the arm or ratchet track) being coupled to the lid and the other to the body of the vehicle or fuel filling aperture.

The cap is described as having a mechanism for rigidly coupling the lid to the body of the cap in its activated state. One embodiment of such a mechanism is described. However, the skilled person will realise that other mechanisms may be used to selectively couple the lid to the body of the cap. For example, the components of the mechanism as described above may be reversed, with a ratchet track of some sort being activated by the trigger, for example, causing regular protrusions to pop up, for engaging with an arm coupled to the body. Alternatively, substantially different ratchet mechanisms may be appropriate, such as a mechanism having ratchets with faces that are substantially parallel to the plane of rotation of the cap that are activated by pressing one towards the other in an axial direction. Other appropriate mechanisms may operate in a similar manner to a bolt and socket, for example the body having a component analogous to a bolt with the lid having a component that fits around or otherwise engages with the bolt when activated.

The nozzle engagement structure described above is designed so as to fit a diesel nozzle and exclude an unleaded petrol nozzle, by virtue of the size of the head that fits into the nozzle channel. Appropriate dimensions for the head, as well as the annular channel around it, are discussed above. A nozzle engagement structure for engaging an unleaded petrol nozzle and excluding a diesel nozzle would have an annular channel with an outer radius too small to accept a diesel nozzle. Again, suitable dimensions to achieve this end are described above.

The skilled person will realise that the different aspects of the embodiments described above may be combined with each other to make new arrangements not specifically disclosed. Furthermore, as mentioned above, there may be alternative aspects available to the skilled person not described here. The embodiments described above are descriptive, and should not limit the scope of the invention. The scope of the invention should only be defined by the appended claims.