BACKGROUND OF THE INVENTION

THIS invention relates to a drain plug. More specifically, the invention relates to a drain plug for making theft of fuel by draining the fuel from standard drain ports in fuel tanks extremely difficult.

Fuel theft has always been a global concern. However, with the ever increasing price of oil, this problem has worsened substantially. Hardest hit is the road transportation industry, with fuel price increases and theft of fuel being the main reasons for forcing many transportation companies to close down.

Many security systems aimed at curbing fuel theft are available in the market. These systems are generally fitted within the fuel tanks of trucks and include fuel level monitoring and alarm systems, e-tag re-fuelling systems and anti-siphoning systems. Although these systems do, to a certain extent, deter thieves from stealing fuel, there is one part of most fuel tanks through which fuel is most prone to theft.

As standard, most fuel tanks comprise a drain port located on or near the bottom of the tank, generally for the purpose of enabling drainage of the tank after cleaning. Normal drain plugs used to seal the drain ports are capable of being removed using standard tools, making drainage of fuel from the tank by removing the drain plug very easy for thieves.

It is an object of the present invention to provide a drain plug that is difficult to remove without a specialised tool, thereby curbing theft of fuel by the process of draining. SUMMARY OF THE INVENTION

According to the invention there is provided a drain plug including:

a bolt comprising a bolt head and a shaft extending from the bolt head;

a sleeve surrounding the bolt head; and

means for retaining the sleeve about the bolt head, the retaining means limiting the axial movement of the sleeve relative to the bolt head while allowing the sleeve to freely rotate about the bolt head.

The bolt head may comprise a top end, a bottom end and sides. Generally, the bottom end of the bolt head further comprises a seal receiving formation for receiving at least a portion of a means for sealing, which sealing means is compressible between the tank and the seal receiving formation of the bolt head thereby in use, with the drain plug fitted in the drain port of the tank, preventing the contents of the tank to leak therefrom. Typically, the seal receiving formation is a groove defined by the bottom end of the bolt head, the groove being sized and shaped to receive at least a portion of the sealing means.

Alternatively, the bottom end of the bolt head may define a sealing face for engaging at least a portion of a means for sealing, which sealing means is compressible between the tank and the sealing face of bolt head thereby in use, with the drain plug fitted in the drain port of the tank, preventing the contents of the tank to leak therefrom. Preferably, the shaft of the drain plug is threadably enegagable with the correspondingly threaded drain port and the sealing means is a crush washer or an o-ring. Where the sealing means is a crush washer, it is most preferable that the crush washer is a copper crush washer.

The cross-sectional shape of the bolt head may be of any shape having one or more sides. Generally, the cross-sectional shape of the bolt head is circular. Typically, the bolt head further includes one or more first engaging formations for engaging with corresponding one or more second engaging formations on a special tool, which in use, is used to tighten or loosen the drain plug. Preferably, the first engaging formations are grooves or keyways defined by the bolt head along the sides thereof and the second engaging formations are corresponding projections or keys protruding radially inwardly from an inner periphery of the special tool. Alternatively, the first engaging formations are projections or keys protruding radially outwardly from the sides of the bolt head and the second engaging formations are corresponding grooves or keyways defined by the special tool along an inner periphery thereof. Preferably, the special tool is a socket for a socket spanner.

The sleeve may be a tubular body having a first open end and a second end on which a radially inwardly projecting flange is located. Generally, the inner periphery of the sleeve is greater than the outer periphery of the bolt head so as to define an annular gap between the sleeve and the bolt head for receiving an engaging end of the special tool. Typically, the height of the sleeve is equal to or greater than the height of the bolt head sides so as to, for the purposes of tighten or loosen the drain plug, prevent sufficient access to the bolt head by any tool other than the special tool.

The bolt head may further define a recess on which the flange of the sleeve is receivable. Generally, the recess is an annular recess defined near the bottom end of the bolt head. Typically, the recess has an outer diameter less than, and a height greater than the inner diameter of a flange defined aperture and the thickness of the flange respectively, thereby allowing the sleeve to freely rotate about the bolt head while the flange is received in the recess, even when the drain plug is tightly fitted to the tank.

The retaining means may co-operate with the flange of the sleeve, or a secondary means for retaining defined by the flange, to axially retain the sleeve about the bolt head. Typically, the retaining means is one or more projections, protrusions or lips protruding radially outwardly from the recess and the secondary retaining means is a groove or chamfer defined along the inner periphery of the flange defined aperture. Preferably, the retaining means is located near the bottom end of the bolt head and further wherein the bolt head and sleeve are fitted together by press fitting.

According to a second aspect of the invention, there is provided a drain plug including:

a bolt comprising a bolt head and an at least partially threaded shaft extending from the bolt head, the shaft being threadably engagable with the drain port;

a sleeve surrounding the bolt head;

means for retaining the sleeve about the bolt head, the retaining means limiting the axial movement of the sleeve relative to the bolt head while allowing the sleeve to freely rotate about the bolt head; and

means for sealing;

such that the sealing means is compressible between the bolt head and the tank thereby in use, with the drain plug fitted in the drain port of the tank, preventing the contents of the tank to leak therefrom.

The bolt head way comprise a seal receiving formation for receiving and locating at least a portion of the sealing means. Typically, the seal receiving formation is a groove defined in a bottom end of the bolt head. Preferably, the sealing means is a crush washer or an o-ring. Where the sealing means is a crush washer, it is more preferably that the crush washer is a copper crush washer.

According to a third aspect of the invention, there is provided a special tool for the tightening or loosening of a drain plug including:

a body; and

engaging formations on the body for engaging corresponding engaging formations on the drain plug.

The body of the special tool may be tubular in shape, having the engaging formations located near a first end of the body and secondary engaging formations for engaging a wrench, spanner or similar leveraging tool located near a second end of the body. Typically, the first end of the body is sized and shaped to be receivable within a gap defined between a drain plug bolt head and a rotating sleeve surrounding the bolt head. Preferably, the engaging formations are grooves or keyways defined along an inner periphery of the special tool, or projections or keys protruding radially inwardly from the inner periphery of the special tool. Most preferably, the special tool is a socket for a socket spanner.

According to a fourth aspect of the invention, there is provided a kit including at least one drain plug and at least one special tool. Preferably, the corresponding engaging formations on the bolt head of the drain plug and the special tool are variable by shape, number, position and size so as to create a plurality of uniquely profiled drain plug and special tool combinations. According to a fifth aspect of the invention, there is provided a database for storage of information relating to the uniquely profiled drain plug and special tool combinations Typically, the unique profile is recorded against a customer specific serial number, pin number, password, identity number, passport number or any other form of identification, such that on request of the customer for additional drain plugs and/or special tools, the customer's unique profile is determinable by interrogating the database with the customer specific serial number, pin number, password, identity number, passport number or any other form of identification supplied by the customer.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a top view of a drain plug in accordance with the present invention;

Figure 2 shows a cross-sectional side view along line A-A of the drain plug illustrated in figure 1 ; and

Figure 3 shows an isometric view of the drain plug and special tool.

DETAILED DESCRIPTION OF THE DRAWINGS

A drain plug according to a preferred embodiment of the invention is designated generally with reference numeral 10. With particular reference to figure 1 and figure 2, the drain plug 10 includes a bolt 12, a sleeve 14, means for sealing 16 and means for retaining 18 the sleeve 14 on the bolt 12.

The bolt 12 comprises a bolt head 20 and a threaded shaft 22. The bolt head 20 has sides 24, a top end 26 and a bottom end 28 from which the shaft 22 extends. The bottom end 28 of the bolt head 12 further defines a seal receiving formation in the form of a circular groove 30, being sized and shaped to receive at least a portion of the sealing means in the form of an o-ring 16. Although the sealing means has been illustrated as an o-ring in the accompanying drawings, it will be appreciated that any other sealing means may be use, for example, a copper crush washer. Where a copper crusher washer is used as a sealing means, the groove 30 may not be necessary in that the copper crusher washer is sealable directly against the bottom end 28 of the bolt head 20 now acting also as a sealing face.

The bolt head 20 is generally of a circular cross-sectional shape. The bolt head 20 defines one or more first engaging formations 32 for engaging with corresponding one or more second engaging formations 34 on a special tool 36 as illustrated in figure 3. The first engaging formations 32 are grooves defined along the sides 24 of the bolt head 20 and the second engaging formations 34 are corresponding projections protruding radially inwardly from an inner periphery of the special tool 36, so as to allow the special tool 36, generally in the form of a socket for a socket spanner, to engage with the bolt head 20 for the purpose of tightening or loosening the drain plug 10 from a drain port 38 defined in a tank 40, or any other container adapted to store a fluid. It will be appreciated that so long as the profiles of the bolt head 20 and the socket 36 correspond, the engaging formations 32, 34 are interchangeable. For example, the inner periphery of the socket 36 may define the engaging grooves that correspond with projections protruding radially outwardly from the sides 24 of the bolt head 20. Preferably, the corresponding engaging formations 32, 34 are variable by shape, number, position and size so as to create a plurality of uniquely profiled drain plug 10 - socket 36 combinations.

For security purposes the unique profile may be recorded in a database (not shown) against customer specific serial numbers, pin numbers, passwords, identity numbers, passport numbers or any other form of identification. On request of the customer for additional drain plugs 10 and/or sockets 36 of a particular profile, and after having passed a security check, that customer's unique profile is determinable by interrogating the database with that customer's specific serial number, pin number, password, identity number, passport number or any other form of identification supplied by the customer.

The sleeve 14 is generally of a tubular shape having a first open end 42 and a second end 44 on which a radially inwardly projecting flange 46 is located. The inner periphery of sleeve 14 is greater than the outer periphery of the bolt head 20 so as to define an annular gap 48 sized and shaped for receiving the first engaging end 50 of the socket 36. The height of the sleeve 14 is also greater than the height of the sides 24 of the bolt head 20 so as to, for the purposes of tighten or loosen the drain plug 10, prevent sufficient access to the bolt head 20 by any tool other than the socket 36.

The flange 46 is received within a recess 52 defined in the sides 24 of the bolt head 20, near the bottom end 28 thereof. The recess 52 has a outer periphery smaller than, and a height greater than the inner periphery of a flange defined aperture and the thickness of the flange 46 respectively, thereby allowing the sleeve 14 to freely rotate about the bolt head 20 even when the drain plug 20 is tightly received in a drain port 38.

The sleeve 14 is retained about the bolt head 20 by retaining means 18 co-operating with the flange 46, thereby retaining the flange 46 within the recess 52. The retaining means 18 is a lip projecting radially outwardly from the bottom of the recess 52 which co-operates with a chamfered edge along the inner periphery of the flange defined aperture. Generally, the sleeve 14 is press fitted to the bolt head 20. It will be appreciated that the retaining means 18 may be any other formation defined on or near the recess 52 and that the retaining formation could be correspondingly co-operative with a secondary retaining formation defined on or near the inner periphery of the flange defined aperture.

In use, the o-ring 16 is pushed over the shaft 22 of the drain plug 10 and into position in the seal receiving groove 30. The drain plug 10 may then be screwed into the drain port 38 of a tank 40 by hand. The socket 36, having a hexagonally shaped second end 54 for engaging a spanner (not shown) is then used to tighten the drain plug 10 into the drain port 38 of the tank 40, thereby compressing the o-ring 16 between the bolt head 20 and the tank 40. Once completely tightened, the o-ring 16 forms a seal between the bolt head 20 and the tank 40, preventing the contents of the tank 40 to pass therethrough.

It will be appreciated that although the invention has been described above with reference to a preferred embodiment, many modifications or variations of the invention are possible without departing from the spirit or scope of the invention.