Field of the Invention

This invention relates to light-weight and disposable portable cooking stoves.

Background to the Invention

Outdoor enthusiasts and military personnel that carry their own equipment need their equipment to be light-weight and suitable for compact storage. This includes their portable cooking equipment. Environments that do not offer a source of fuel, such as dried wood, are frequently encountered, requiring the prudent person to also carry their own fuel. Solid-fuel blocks are a particularly light-weight fuel option and their typically high energy density and resulting intense burn characteristics allow for smaller stove sizes than other fuel sources.

To use a portable cooking stove with a solid-fuel block, the fuel block is placed in the combustion chamber of the stove and a cooking vessel is placed on top of the stove or inserted into the stove. The solid fuel is set alight and the flames heat the cooking vessel. The cooking stove will typically have one or more air inlets to allow oxygen to get to the burning fuel and will typically have a means of allowing exhaust gas to exit the combustion chamber.

As well as simply heating food and drink, portable cooking stoves provide the vital ability to sterilise food and water. With no consumer standards of performance set for portable stoves, the only benchmarks available are those used by military organisations. These tough standards specify that the stove must be light-weight, robust and capable of raising water from near freezing point to boiling point and then to hold the boil for at least 5 minutes. For heating ready-to-eat, pre-packed meals, the stove must be able to raise a standard meal pack of 500 grams in weight plus 250 ml water to a minimum of 65°C. These standards clearly require that the stove plus fuel combination be highly efficient.

Many prior art stoves are of a fixed construction and rigidly define the combustion chamber. Such stoves do not collapse for storage and can therefore take up a lot of room in, for example, a backpack. A better option for storage is a stove that can be disassembled or rearranged when not in use. When required for use, the stove can then be assembled or otherwise rearranged to the open form. Light-weight portable cooking stoves that can be dismantled and packed in a flat configuration are known in the prior art. Also known are stoves that have hinges, and these stoves can fold at the hinge into a flat configuration.

Prior art portable cooking stoves that can be collapsed for storage are, however, typically designed to be robust and have a long usage lifetime. This requires manufacturing the stove from strong material, which adds weight. Such stoves would also typically not be used as disposable stoves.

A market exists for a light-weight and collapsible stove that can be used a limited number of times, such as on a day or weekend of hiking, and then simply disposed of. Such a stove would need to be inexpensive, and this in turn means that manufacture of the stove must be simple, rapid and use inexpensive materials. A conflicting consideration, however, is that the stove must be able to safely support full cooking vessels when in use at high temperatures. The present invention aims to meet this need in the market.

Summary of the Invention

According to a first aspect, the invention provides a portable cooking stove comprising a strip of malleable material connected at its ends to form a loop, wherein two opposing regions of the loop are folding regions, and wherein the material between the opposing folding regions can be moved between an open configuration, and a closed configuration, in which the loop is folded substantially flat; wherein when the loop is in the closed configuration, the cross-section of each folding region substantially defines a circular or tear-drop shape; and wherein there are two or more holes in each folding region.

The inventor has made a cooking stove that is portable and light-weight by using a loop of malleable material that can simply be pressed flat for storage and pulled open for use. The stove of the present invention is designed to be disposable after a limited number of uses, typically 1 to 15. This means that it is ideal to use on a day or weekend trip, where it is anticipated that a stove will be needed a few times and then disposed of.

Repeated opening and closing of a stove around a fold line quickly leads to material fatigue and to a tear forming along the fold line. Prior art folding stoves all suffer from early failure around a fold line. Efforts to improve the failure rate inevitably lead to a thicker material being used, which increases the weight of the stove, and the cost.

Through extensive investigations, the inventor has found that a folding stove can be improved by using circular or tear-drop shaped folding regions rather than sharp folding regions. By introducing a continuous curve at the folding region, the strain on the material during folding and unfolding is distributed across the curve. The number of opening and closing cycles before tearing occurs is therefore significantly increased. In the stove of the present invention this is achieved without the need for complex and expensive additional components. These curved folding regions therefore extend lifetime of the one-piece stove without adversely affecting weight, ease of use, cost of components or ease of manufacture.

The stoves of the present invention include two or more holes in each folding region. By having holes in the folding region, any tears that are propagating through the material will be halted when they reach the holes. These holes therefore increase the number of usage cycles of the stove even further, in addition to the use of the curved folding regions.

In a preferred embodiment, these holes are located in the most likely region for tears to occur, such as the outermost facing arc of the folding region. In this way, the lifetime of the stove is maximised without unnecessarily compromising structural integrity.

Furthermore, using folding regions that have a cross-section that substantially defines a circular or tear-drop shape exploit the structural stability of cylindrical objects. This allows the stove to bear heavier weights without buckling, or, alternatively, allows the stove to be manufactured from a thinner material.

The stove of the present invention has a closed configuration. This means that the portable cooking stove of the present invention can be very easily flat-packed for storage, providing multiple advantages over non-collapsible stoves. First, the flattened stove takes up less space, making it more likely to fit in a bag. Second, any soot or other dirt from cooking with the stove is contained on the inside of the loop, preventing mess spreading. Third, there are no operationally difficult steps in assembling or disassembling the stove, such as connecting halving joints, hinges, clips or other j oining methods.

The stove of the present invention is a single piece. This has the advantage that there are no components that can be accidentally lost.

The cooking stove of the present invention comprises malleable material. The malleable nature of the material provides another advantage. In some embodiments the cooking vessel is balanced on top of the stove. In other embodiments, the cooking vessel may be inserted into the stove, particularly with cooking vessels that increase in cross-sectional area towards the top of the cooking vessel. With unusually shaped cooking vessels, such as kidney cups, the stove can easily be moulded to form an intimate fit around the contours of the cooking vessel, thus maximising efficiency of heat transfer from the fuel to the cooking vessel.

In yet another method of increasing lifetime of the stove, in a preferred embodiment the stove is horizontally symmetric. If a tear occurs on the top edge of the stove, the stove can simply be turned upside down to prevent further damage that may be caused by inserting a cooking vessel into the stove. In a preferred embodiment of the invention, the stove has an air entry and/or exhaust port, preferably one that is large enough to allow solid fuel blocks to be passed through. This ensures that more fuel can be fed to the stove without having to move the cooking vessel. In turn, this allows the cooking stove to be of a smaller size and therefore lighter and more compact.

The stove has two opposing folding regions, and two sections of material connecting these folding regions. Optionally, one of these sections has air entry and/or exhaust ports while the other section does not. A number of useful features arise from this strategy. First, the structural integrity of the stove is maximised, and, second, the section with no ports can be faced into the wind, to act as a wind-shield.

The stove is designed to be disposable. By manufacturing the stove from a degradable material, such as thin steel or aluminium, the stoves can be disposed of by burial and will degrade.

According to a second aspect, the invention provides a method of manufacturing a portable cooking stove according to the first aspect of the invention, the method comprising: (a) selecting a sheet of malleable material and cutting the sheet of material into the required shape; (b) forming a loop by connecting two opposing ends of the material using staples, spot welds, an adhesive, halving joints, clips, or any combination thereof; (c) forming opposing folding regions around circular or teardrop shaped templates; and (d) flattening the material between the opposing folding regions to provide the portable cooking stove in the closed configuration.

By requiring no components in addition to a single strip of material, and carefully shaping it into a loop, the inventor has provided a stove that is inexpensive and easy to manufacture. There are also options for the sequence of events used to manufacture the stove. For example, a net of the stove can be cut followed by folding and connecting the two ends. Alternatively, a much larger net can be cut followed by folding and connecting the two ends, and then individual stoves are cut from this finished loop.

According to a third aspect, the invention provides a method of cooking food using a portable cooking stove according to the first aspect of the invention, in which a cooking vessel is balanced on top of the portable cooking stove or is inserted into the portable cooking stove to form an intimate fit with the portable cooking stove.

According to a fourth aspect, the invention provides a kit comprising one or more portable cooking stoves according to the first aspect of the invention and one or more solid fuel blocks.

Brief Description of the Drawings

Figure 1 shows a portable cooking stove according to a preferred embodiment of the present invention in the closed configuration.

Figure 2 shows the portable cooking stove of Figure 1, but in the open configuration. Figure 3 shows the portable cooking stove of Figure 2, but with a cooking vessel balanced on top of it. The cooking vessel is shown as transparent to allow detail of the stove to be seen.

Figure 4 shows another portable cooking stove according to a preferred embodiment of the present invention in the flat-packed configuration. Figure 5 shows the portable cooking stove of Figure 4, but in an open configuration suited to receiving a kidney-shaped cooking vessel.

Figure 6 shows the portable cooking stove of Figure 5, but with a kidney-shaped cooking vessel inserted into the top of the stove.

Description

This invention relates to a portable cooking stove. By portable we mean that the stove can easily be carried by one person. It is envisaged that the stove will primarily be used by those undertaking camping or other outdoor leisure pursuits.

The portable cooking stove comprises a strip of malleable material. By strip, we mean that the material is generally a thin, flat material. The material may be substantially square or rectangular in shape, for making a stove with vertical walls, or may be an arc shape, for making a conical frustum shaped stove. By malleable, we mean that the material may be deformed and, once deformed, will hold its deformed shape. The strip of malleable material is connected at its ends to form a loop. By loop, we mean that two opposing edges of the strip of material are connected together so that the material forms a continuous circuit. This may be achieved by the two opposing edges being aligned to abut each other, or the two ends may slightly overlap. In an open configuration the stove may therefore take the appearance substantially of a circular or elliptic cylinder or a conical frustum. An elliptic cylinder is a cylinder with an oval cross-section.

Two opposing regions of the loop are folding regions. By opposing regions, we mean a regions that are at the furthest point on the loop from each other. The first region may be arbitrarily chosen, or may be selectively chosen with respect to the connecting region. By folding region, we mean a region where the material of the stove substantially folds back on itself.

The stove can be in an open configuration. In an open configuration the loop substantially defines a circular or elliptic cylinder, a conical frustum, or other shape complementary to a cooking vessel such as a kidney-shape. By this, we mean that, excluding the folding regions, the stove has the appearance of a circular or elliptic cylinder, a conical frustum or kidney-shape. The stove can also be in a closed configuration, where the loop is folded substantially flat. By this, we mean that the two sections of material between the folding regions are pressed against each other and substantially form a flat configuration. The stove can be moved between the open configuration and the closed configuration. This means that the user can manipulate the material of the stove in between the opposing folding regions by pulling the stove open or pressing it closed.

In the closed configuration, the cross-section of the folding regions substantially defines a circular or tear-drop shape. In contrast to prior art folding stoves, the folding region is not simply a sharp fold line. The folding region has a circular or tear-drop shaped cross section. The material of the stove adjacent to the folding region comprises two sheets of material pressed flat against each other. Where the material begins to define the folding region, the two sheets separate from each other, creating a hollow void. The material defines a circular or tear-drop shape around this void, appearing substantially as a cylinder.

By "in the closed configuration" we are referring to the fact that the folding region has a circular or tear-drop shaped cross section primarily when the two sheets of material comprising the remainder of the stove are pressed together in the flat configuration. When manipulated into the open configuration, the cross-sectional shape of the folding regions may distort, and open out to some extent.

As described above, having curved folding regions is advantageous with respect to folding lines as in prior art stoves, because it greatly improves the life time of the stove.

There are two or more holes in each folding region. These holes can be found anywhere in the folding region, although they are preferably located in areas more likely to be subject to tearing. For example, these holes may be found along the outermost facing arc of the folding region. By this, we mean that the holes may be located in a line from top to bottom of the stove wall, this line in the folding region being the line that is at the furthest point from the opposing folding region. As described above, providing holes in the folding regions is highly advantageous as it improves the lifetime of the stove by stopping tears from propagating through the whole side. It is preferred that there are more than two holes, preferably 3 to 10 holes.

Each circular or tear-drop shaped folding region may take up less than 15%, preferably less than 10%, more preferably less than 6%, of the length of the loop. By length of the loop, we mean the distance defined by circumnavigating the loop. Each folding region should only be fabricated from a small percentage of this distance. The stove may be substantially horizontally symmetric. By this, we mean that the stove should have a similar appearance if it is turned upside down. This has the advantage of allowing the stove to be used another way up, if one end has become fatigued, thereby increasing the lifetime of the stove.

The stove may comprise at least one air entry and/or exhaust port. Air entry and exhaust ports are important for providing oxygen to the burning fuel and removing exhaust fumes from the stove. There may be separate air entry and exhaust ports, where the exhaust ports will generally be located above the air entry ports, or one large port may perform both functions. Where the stove can be turned upside down, the air entry and exhaust ports may switch roles depending on the orientation of the stove.

At least one air entry and/or exhaust port may be sized to allow solid fuel blocks to be passed through. This is so that when one fuel block is almost used up, the next fuel block can be inserted into the stove without having to remove the cooking vessel.

One of the sections of the stove between the two folding regions may have no air entry or exhaust ports. The stove comprises two folding regions at opposing edges of a loop. The remainder of the loop comprises two sections of material between these folding regions, which make up the bulk of the stove. One of these sections of material may have no air entry or exhaust ports. That is, any air entry and exhaust ports are located only in one section of material. This means that one face of the stove has no air entry or exhaust ports. This is advantageous, as it can provide a shield against the wind. The face with no parts would be positioned in to the wind during use to maximise the benefit. This would also shield the light which reduces visibility of the stove, an advantage particularly in military applications.

The malleable material may be a metal or heat-stable plastic. The malleable material may be degradable. This would mean that the majority of the stove would be degradable. The material may also have heat annealing properties. That is, when the material goes through a heating and cooling cycle, the material loses brittleness making it less likely to tear. Aluminium is an example of a heat-stable, degradable material that undergoes annealing when heated.

The malleable material may have a thickness between 0.05 mm and 2 mm, preferably between 0.1 mm and 1 mm, more preferably between 0.2 mm and 0.5 mm.

The thickness of material was selected to be a balance between being light in weight but also structurally strong enough to support a filled cooking vessel without buckling, even with air vents cut into the material of the stove. This provides a light-weight one-piece stove that can be used a number of times and, through its simplicity, is inexpensive to manufacture.

The method of connecting the two opposing edges of the strip of malleable material is not particularly limited. Ideally, the two opposing edges of the strip of malleable material are positioned to form a loop and are secured with staples, spot welds, an adhesive, halving joints, clips, or any combination thereof.

The invention also provides a method of manufacturing a portable cooking stove according to the first aspect of the invention. Step (a) involves selecting a sheet of malleable material and cutting it to the required shape. By this, we mean starting with a substantially flat sheet of material that the stove is to be made of. This material should be of the thickness that has been determined as suitable for the stove walls. The material can be cut to shape by, for example, a die-cutting machine. At this stage, air inlet ports and/or exhaust ports may also be cut into the material of the stove. The material can be cut either as a net of a single stove, or as a net for a taller loop that is then cut into multiple stoves at a later stage in the manufacturing process.

Step (b) involves forming a loop by connecting two opposing ends of the material using staples, spot welds, an adhesive, halving joints, clips, or any combination thereof. The material will generally be of a shape that has two opposing and substantially straight edges. These edges may be parallel so that the loop defines a cylinder, or the shape may substantially define an annular sector so that the loop defines a conical frustum. Step (c) involves forming opposing folding regions around circular or tear-drop shaped templates. This step forms the folding regions. This can be done by wrapping the material of the stove around a suitably shaped template, such as a metal bar with a circular or tear-drop shaped cross section. Ideally, the material of the stove should be wrapped around substantially the whole perimeter of the cross section.

Step (d) involves flattening the remainder of the loop. The folding regions have a circular or tear-drop shaped cross section, with a hollow void, and should not be flattened. The remainder of the stove, however, is two sheets of material, each connecting the two folding regions. By flattening the material between the opposing folding regions to provide the portable cooking stove in the closed position, we mean pressing these two sheets of material against each other and substantially ensuring that they form a flat configuration.

Normally, steps (a) to (d) would be carried out sequentially. However, steps (b) and (c) can be switched. That is, the formation of the circular or tear-drop shaped folding regions can be formed before connecting the opposing edges to form the loop. The invention also provides a method of cooking food using a portable cooking stove according to the first aspect of the invention. The cooking vessel may be balanced on top of the portable cooking stove when the stove is in the open configuration. As discussed above, the open form of the stove may be substantially oval or circular in cross section. To open the stove, starting with the closed, flattened configuration of the stove, the user can pull the two sides apart so that the stove is transitioned to the open configuration. In doing so, the user may choose to form a substantially circular, or cylindrical, open configuration. The user may not wish to go open the stove to a full cylinder, and may instead only open the stove as far as having an oval cross section, which is what we mean by an elliptic cylinder. These open configurations avoid introducing sharp fold lines to the stove.

Alternatively, the cooking vessel may be inserted into the stove. This would typically apply to a cooking vessel that had a larger cross sectional area towards the top of the cooking vessel such that the bottom of the cooking vessel would drop into the stove, but the top would prevent the cooking vessel fully entering the stove. The cooking vessel should rest high enough that there is enough space for the fuel to burn effectively.

The cooking vessel inserted into the portable cooking stove may form an intimate fit with the portable cooking stove. Owing to the malleable nature of the stove, the stove walls can be manipulated by the user such that they are moulded around the contours of the cooking vessel. The shape of the stove can be moulded to form an intimate fit with unusually shaped cooking vessels, such as kidney-shaped cups. This is useful for military applications, where kidney-shaped cups are standard issue.

The invention also provides a kit comprising one or more portable cooking stoves according to the first aspect of the invention and one or more solid fuel blocks. The stove is ideally used with solid fuel blocks. As both the stove and the fuel blocks are consumable items, a kit can be made comprising a stove and a number of fuel blocks suited to the expected lifetime of the stove. The solid fuel blocks can comprise hexamine, trioxane, or preferably solidified methyl decanoate.

Detailed Description of the Drawings

Figure 1 shows a portable cooking stove 1 according to the present invention in a closed configuration. The portable cooking stove comprises a loop of material 2 with two folding regions 3. The folding regions have holes 4 positioned to prevent tears from propagating along the length of the folding region. This embodiment of the portable cooking stove has a single air inlet/outlet 5.

Figure 2 shows the portable cooking stove 1 of Figure 1, but in the open configuration. It can be seen that the loop of material 2 has a curved appearance and substantially forms an elliptic cylinder, i.e. has an oval cross-section. The folding regions 3 have been distorted from their appearance in the flat configuration. Figure 3 shows a cooking vessel 6 balanced on the open configuration of the cooking stove 1 of Figure 2.

Figure 4 shows a different embodiment of the cooking stove 7 according to the present invention in a closed configuration. This embodiment again comprises a loop of material 2 with two folding regions 3. The folding regions have holes 4 positioned to prevent tears from propagating along the length of the folding region. This embodiment of the portable cooking stove has multiple air inlets/outlets 5. Figure 5 shows the portable cooking stove 7 of Figure 4, but in on open configuration suitable for receiving a kidney-shaped cooking vessel. The loop of material 2 has a kidney-shaped cross-section. The folding regions 3 have been distorted from their appearance in the flat configuration. Figure 6 shows a kidney-shaped cooking vessel 8 inserted into the portable cooking stove 7 of Figure 5. The loop of material 2 has been moulded around the cooking vessel 8 to form an intimate fit.

During use, solid fuel blocks are put inside the stove 1 and burned, to heat the contents of the cooking vessels 6 and 8.