ANTI-THEFT DEVICE FOR MOTOR VEHICLE FUEL TANK

Abstract

An anti-siphoning device for vehicle fuel tanks includes a barrier in the form of a honeycomb with hexagonal openings located between the fuel tank inlet and the tank itself. The device includes a retractable extension to accommodate a fuel refilling nozzle and openings to allow air in and out of the tank, which makes the refilling process easier.

Description

FIELD OF THE INVENTION

This invention relates to an anti-siphoning device for a motor vehicle fuel tanks.

BACKGROUND OF THE INVENTION

The Applicant is aware of a device which is fitted to the fuel tank opening which prevents insertion of a siphon to empty the tank. However the device has the undesirable side effect of substantially increasing the time required to refuel each tank. As each truck usually has multiple tanks, this results in an unacceptable time cost to the operator.

It is therefore an object of this invention to provide an anti-siphoning device which prevents loss of fuel without compromising the time taken to refuel the tanks. It is a further object of this invention to provide an anti-siphoning device which is universal and capable of fitment to a wide variety of vehicle fuel tanks.

THE INVENTION

According to the invention, an anti-siphoning device for motor vehicle fuel tanks comprises a cylindrical housing securable within the fuel tank inlet; anchoring means for securing the housing within the inlet, a buffer to prevent insertion of a siphon tube element and an extensible neck element movable from a first position in which insertion of a fuel pump nozzle is prevented, to a second position in which the device has sufficient depth to receive the fuel pump nozzle for the purposes of filling the tank, the housing defining a passage between the tank inlet and the housing for free flow of air into and out of the tank during filling, the passage being in communication with the atmosphere by means of one or more air vents located in the housing.

In the preferred form of the invention, the buffer element and extensible neck element comprise a pair of concentric cylindrical elements locatable within the cylindrical housing, the buffer element comprising the innermost cylinder and including at the upper end thereof a grid affixed thereto and the neck element being slidable between the housing and the buffer element. The housing preferably includes a pair of vertical slots including at the upper ends thereof a horizontal slot, in which guide formations on the perimeter of the neck element are slidable. These permit vertical movement of the neck element as well as providing a means to retain the neck element in the extended position during filling.

The housing preferably includes a circumferential flange at the top end thereof with the air vent being located spaced apart around the collar.

The bottom end of the cylindrical housing includes one or more formations for retaining the buffer and neck elements and preventing them from slipping into the tank. In the simplest form, the formation comprises an inwardly directed circumferential flange providing ledge on which the bases of the neck and buffer elements rest. In a preferred form, a second grid is provided which also acts as a further barrier to insertion of narrow-diameter siphon-tube. In the preferred form, the grid pattern comprises a plurality of half-hexagonal apertures.

The neck element includes at the upper end thereof a collar about the opening thereof to engage the inner diameter of the housing, the collar being provided with a pull-ring or the like formation for lifting it into the extended position required for filling.

In the preferred form of the invention, the upper grid is circular in shape and comprises a plurality of hexagonal apertures within the perimeter of the circle. Save for the apertures at the perimeter of the grid, all apertures are hexagonal as the Applicant has established that this shape permits the lowest interstitial surface area which accordingly reduces resistance to flow of the fuel therethrough and thereby reduces splash back and frothing. This reduction of surface area can also be achieved with square apertures.

In the preferred form of the invention, the cylindrical housing is securable within the tank inlet by means of a mounting plate which comprises a ring element including two or three spaced-apart lugs each adapted to receive a bolt, depending on the make of truck to which it is to be fitted. The flanges engage cutout formations in the filler neck and the filler neck may have either two or three cut outs. When the device of the invention is fitted, the lugs are inserted into the cutouts and the ring element is rotated until the lugs abut against stopper elements at which point the bolts in the lugs are tightened and further bolts are inserted to prevent reverse rotation of the ring element.

The circumferential flange of the cylindrical housing engages by means of feet located on the underside of the flange and the bolts extend through the circumferential flange of the cylindrical housing. In this form of the invention, the position of the housing and neck and buffer elements is adjustable by tightening or loosening the bolts to draw them closer to the top of the tank inlet or urge them further away, respectively. This enables the device of the invention to fit better in a wider range of fuel tanks as these tanks have filler necks at the tank inlets which vary widely in size in different vehicles. In addition the dimensions of the feet may differ to facilitate fitment in different vehicles.

In operation, when the fuel tank of a vehicle is required to be filled, the neck element is pulled upwards using the pull-ring and rotated to keep it in the extended position. When in the first position described in earlier paragraphs, the device of the invention prevents insertion of not only a siphoning device but also a fuel-pump nozzle because of the proximity of the honeycomb grid to the top of the tank inlet. In the extended position, the neck element provides sufficient depth for insertion of the nozzle.

Fuel flows virtually unobstructed through the honeycomb grid into the tank while displaced air from the tank flows upwards around the cylindrical housing of the device, and out through the air-vents located around the flange. The efficiency of the honeycomb grid as an inlet to the fuel together with the separation of the flow passages of fuel in and air out reduce splash back and frothing of the fuel, substantially decreasing filling times associated with prior art anti-siphoning device of a similar nature.

In an alternative form of the invention, the housing is not mounted on a ring mounting plate, but is instead provided with a series of spaced-apart spring clips which are biased to engage the underside of the circlip to prevent removal. This form of the invention is typically used for inlet tanks which include a circular groove within the inlet. In this form of the invention, the mounting plate is replaced by a circlip ring which fits underneath the circumferential flange of the cylindrical housing and engages the circular groove in the inlet and in so doing ensures a firm mounting for the anti-siphoning device of the invention.

EMBODIMENT OF THE INVENTION

Embodiments of the invention are described below with reference to the accompanying drawings in which:

FIG. 1A is an isometric view of an anti-siphoning device of the invention;

FIG. 1B is an isometric view of an anti-siphoning device of the invention mounted with a fuel tank inlet;

FIG. 1C is an isometric view of an anti-siphoning device adapted to receive a screw-threaded cap;

FIG. 2 is a similar view of the device of FIG. 1B with the neck element in extended condition for fueling;

FIGS. 3 and 4 are bottom isometric views of FIGS. 1B and 2 respectively;

FIGS. 5 and 6 are cutaway views of FIGS. 1B and 2;

FIGS. 7 and 8 are cutaway views of FIGS. 3 and 4;

FIG. 9 is an isometric view of one form of a ring mounting element;

FIG. 10 is an isometric view of an alternative form of the invention;

FIG. 11 is a cutaway isometric bottom view of FIG. 1C; and

FIG. 12 is an alternative cutaway view of the device of FIG. 1C.

In FIGS. 1 to 12, an anti-siphoning device 10 to prevent fuel being siphoned from motor vehicle tanks, fits within the inlet of the tank.

The truck tank inlet includes an integral filler neck which may differ in dimensions from vehicle to vehicle.

The device of the invention comprises includes an adaptor 12 which fits onto the truck filler neck and cylindrical housing 14 which includes at the top end thereof a circumferential flange 16. Within the housing is a concentric arrangement with an extensible neck element 18 and buffer element 20 which has a honeycomb grid 22 at the top end thereof to prevent insertion of a pipe or tube for siphoning purposes.

The neck element 18 includes a collar 24 for engaging the internal edge of the flange 16 when in the position of FIG. 1 in which no filling of the tank is taking place. A pull-ring 26 is provided to assist in sliding the neck element from the position of FIG. 1 to the extended position of FIG. 2 to fill the tank. The external surface of the neck element is provided with a guide formation 28 which slides in slot 30 cut in the cylindrical housing 14. The slot includes a horizontal section 32 at the top end thereof which enables the neck element to be rotated to the end of slot 32 (as shown in FIG. 2) to be retained in the extended position during filling.

At the bottom end of the housing 14, a second grid 34 is provided and secures the bases of the housing (14) and buffer (20) elements to the grid 34 by means of welds at 40. This renders the housing 14 and buffer element 20 fixed while the neck element 18 is free to slide. The grid 34 has a half-honeycomb grid pattern 35. The lower end of the housing further includes horizontally orientated slots 37 to assist free flow of fuel and reduce splash back.

The housing 14 is secured in the inlet by means of bolts 42 which extend through the flange 16 to engage lugs 44 on mounting ring 46 as shown in FIG. 3.

During fitment, the mounting ring is inserted into the truck filler neck with the lugs 44 entering cutouts 47 in the adaptor 12. The ring is then rotated until the lugs abut stopper elements 49. Once the neck and buffer elements have been slided into the housing, the bolts 42 are tightened to draw the ring upwards to engage the underside of the filler neck of the vehicle. Feet 50 are provided on the underside of the flange 16 to centralize the anti-siphoning device 10. Locking screws 43 prevent forced removal of the device. The bolts 42 permit adjustment of the distance between the flange 16 and the mounting ring 46, to allow fitment in a variety of fuel tanks having filler necks of different dimensions.

When the neck 18 is in extended position required for filling as shown in FIGS. 2, 4, 6 and 8, there is sufficient depth for insertion of a fuel-pump nozzle into the neck. Fuel is pumped through the honeycomb grid 22 into the tank, and air displaced by the fuel flow upwards around the outside of the housing 14 and out through vents 48 in flange 16.

This arrangement ensures that flow of air and fuel remains discrete from each other and accordingly prevents frothing from reducing the speed of fuel that can enter the tank.

Turning to FIG. 10, an alternative form of anti-siphoning device is shown. The method and principle of operation remains identical, but the method of mounting the device within the tank inlet differs. In this form, a circlip 52 is provided which engages a circular groove in the tank inlet on one hand, and the underside of flange 16 on the other. Spring clips 54 also engage the underside of the circlip 52 to prevent removal.

In FIGS. 1C and 11, and 12 the truck filler neck is screw-threaded to receive a cap (not shown). In this form, securing of the housing in the tank inlet is achieved by the flange 16 resting on the tank inlet and internally screw-threaded 56 adaptor 12 being secured to the truck tank inlet by means of dowel pins 60 which engage the screw-thread of the tank inlet and prevent removal. The flange 16 is held between the adaptor 12 and the inlet by means of lip 62 which is shaped for this purpose.

Claims

1. An anti-siphoning device for motor vehicle fuel tanks comprising a cylindrical housing securable within the fuel tank inlet; anchoring means for securing the housing within the inlet, a buffer to prevent insertion of a siphon tube element and an extensible neck element movable from a first position in which insertion of a fuel pump nozzle is prevented, to a second position in which the device has sufficient depth to receive the fuel pump nozzle for the purposes of filling the tank, the housing defining a passage between the tank inlet and the housing for free flow of air into and out of the tank during filling, the passage being in communication with the atmosphere by means of one or more air vents located in the housing.

2. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 1 in which the buffer element and extensible neck element comprise a pair of concentric cylindrical elements locatable within the cylindrical housing.

3. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 1 in which the buffer element comprises the innermost cylinder and includes at the upper end thereof a grid affixed thereto.

4. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 1 in which and the neck element is slidable between the housing and the buffer element.

5. An anti-siphoning device for motor vehicle fuel tanks as claimed in any of claim 1 in which the housing includes a pair of vertical slots including at the upper ends thereof a horizontal slot, in which guide formations on the perimeter of the neck element are slidable.

6. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 5 in which the guide formations permit vertical movement of the neck element as well as providing a means to retain the neck element in the extended position during filling.

7. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 1 in which the housing includes a circumferential flange at the top end thereof with the air vents being located spaced apart around the collar.

8. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 1 in which the bottom end of the cylindrical housing includes one or more formations for retaining the buffer and neck elements and preventing them from slipping into the tank.

9. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 8 in which the formation comprises an inwardly directed circumferential flange providing a ledge on which the bases of the neck and buffer elements rest.

10. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 8 in which the formation comprise welds.

11. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 1 in which the neck element includes at the upper end thereof a collar about the opening thereof to engage the inner diameter of the housing, the collar being provided with a pull-ring or the like formation for lifting it into the extended position required for filling.

12. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 3 in which the grid is circular in shape and comprises a plurality of hexagonal apertures within the perimeter of the circle.

13. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 1 in which the grid is circular in shape and comprises a plurality of square apertures within the perimeter of the circle.

14. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 1 in which the cylindrical housing is securable within the tank inlet by means of a mounting plate which comprises a ring element including two or three spaced-apart lugs each adapted to receive a bolt

15. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 1 in which an adaptor is provided to secure the housing in the tank inlet.

16. An anti-siphoning device for motor vehicle fuel tanks according to claim 15 in which flanges engage cutout formations in the adaptor and the adaptor has either two or three cut outs.

17. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 16 in which, when the device is fitted, lugs are inserted into the cutouts in the adaptor and the ring element is rotated until the tugs abut against stopper elements at which point the bolts in the lugs are tightened and further bolts are inserted to prevent reverse rotation of the ring element.

18. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 7 in which the circumferential flange of the cylindrical housing engages by means of feet located on the underside of the flange and bolts extend through the circumferential flange of the cylindrical housing.

19. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 18 in which the position of the housing and neck and buffer elements is adjustable by tightening or loosening the bolts to draw them closer to the top of the tank inlet or urge them further away, respectively.

20. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 18 in which the dimensions of the feet differ to facilitate fitment in different vehicles.

21. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 1 in which the housing is provided with a series of spaced-apart spring clips, and the mounting plate is replaced by a circlip ring which fits underneath the circumferential flange of the cylindrical housing and engages the circular groove in the inlet, the spring clips being biased to engage the underside of the circlip to prevent removal.

22. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 15 in which the adaptor is internally screw-threaded to engage the correspondingly screw-threaded tank inlet/filler neck, the circumferential flange being held between the tank inlet and a lip formation in the underside of the adaptor.

23. An anti-siphoning device for motor vehicle fuel tanks as claimed in claim 22 in which the adaptor is secured with dowel pins which prevent the adaptor being unscrewed.

24. (canceled)