The present invention relates to a portable collapsible stove.
Portable collapsible stoves are well known and many different types have been proposed. Such stoves can be easily carried in a backpack or the like, and may be known as ‘single’ stoves in that they are arranged to heat food or liquid in a single container. Some of the prior art stoves comprise some sort of collapsible metal frame arranged to provide a fuel locating region, and supports to support a container above the fuel. It has been previously proposed to provide a portable collapsible stove formed from rigid metal sheets hinged together to form an outer windshield and an inner fuel support platform. Such prior proposals are typically relatively heavy, noisy and dirty to use, and provide inefficient, uncontrolled combustion.
We have provided an early solution to the above problems with the portable collapsible solid fuel stove described in our European patent application EP 1957870 of 18 Jul. 2006.
The present invention stems from significant developments of our above stove, and from work in providing an improved solution to the above problems.
According to a first aspect of the invention there is provided a portable collapsible stove, the stove being formed from sheet laminate material, the laminate material comprising at least one planar sheet of a metal material adhered to, at least one planar non-metallic substrate, the stove comprising a plurality of side walls formed from the sheet laminate material, each side wall comprising a pair of side margins, the side margins of adjacent side walls being fastened together such that the side walls together define a tube one end of which comprises a base which rests in use on the ground and an opposed end of which comprises a mouth to at least partially receive, and support, in use a container or the like, the stove further comprising a fuel support platform also formed from the sheet laminate material, the fuel support platform being located inside the tube at a position spaced from the base of the tube, with the outer periphery of the fuel support platform being fastened to the side walls, at least one air inlet aperture being provided in a side wall below the fuel support platform, at least one exhaust aperture being provided in a side wall above the fuel support platform, the combination of the structure of the sheet of laminate material, the fastening of the side margins of adjacent side walls and the fastening of the outer periphery of the fuel support platform being such that the stove can be collapsed from an operational condition in which the side walls define the tube and the fuel support platform extends across the tube, to a collapsed, substantially flat condition in which the side walls and fuel support platform are substantially parallel. The stove may further comprise at least one aperture shield arranged to extend across each inlet and exhaust aperture to block light emitted through each aperture in use. The at least one aperture shield may comprise a vent spaced from the aperture and operative to allow gas flow through the aperture. Preferably all of the apertures are covered by at least one of the shields. Each of the shields may cover only one, or more than one, of the apertures.
Preferably each aperture shield comprises an oblong flap fixed to the respective wall of the stove below the inlet or exhaust aperture in question, the upper part of the flap not being fastened to the respective wall, and so defining a vent in communication with the inlet or exhaust aperture in question.
Preferably the or each flap is movably mounted on the respective wall so as to be movable from an operational condition in which the upper end of the flap is distal from the respective wall, to a partially collapsed condition in which the upper end of the flap is adjacent the respective wall.
Preferably the side margins of the flap are fastened to the respective wall by way of pleated sides which allow the flap to be moveable between the operational and collapsed conditions.
Preferably the sheet laminate material further comprises an anti-reflecting coating. The coating may be provided on a surface of the material which forms an outer surface of the stove in use. The surface may be formed by the metal foil, or may be formed by the non-metallic substrate. The anti-reflecting coating may comprise matt black paint, or it may comprise graphite, or it may comprise PTFE.
Preferably the walls are fastened together using stitching incorporating a fire retardant thread. The fire retardant thread may comprise a glass fibre thread. The fire retardant thread may be impregnated and/or coated with PTFE and/or Graphite. The Graphite renders the thread black and therefore of low visibility.
Preferably the fuel support platform is fastened to the tube using a fire survivable fastener.
Preferably the fire survivable fastener comprises stitching incorporating a fire retardant thread.
The fire survivable fastener may comprise a metallic or non-metallic material. The fire survivable fastener may comprise a staple or rivet for example, or may comprise adhesive. Combinations of any of stitching, rivets, staples and adhesive are envisaged as may be required to meet structural, manufacturing or cost based objectives.
Preferably a pull tab is provided on the underside of the fuel support platform, a user pulling the pull tab to assist with moving the stove from the collapsed condition to the operational condition.
Preferably the side margins of each wall are bent outwardly from the plane of the wall to define a side wall fin, adjacent side wall fins being fastened together.
The non-metallic substrate of the sheet of laminate material may comprise a glass fibre mat. The non metallic substrate may be impregnated and/or coated with PTFE.
According to a second aspect of the invention there is provided a portable collapsible stove, the stove being formed from sheet laminate material comprising two opposed planar sheets of a metal foil material which together sandwich, and are adhered to, a planar non-metallic substrate, the stove comprising a plurality of oblong walls formed from the sheet laminate material, each wall comprising a pair of side margins, the side margins of adjacent walls being joined together such that the walls together define a tube one end of which comprises a base which rests in use on the ground and an opposed end of which comprises a mouth to at least partially receive, and support, in use a container or the like, the stove further comprising a fuel support platform also formed from the sheet laminate material, the fuel support platform being located inside the tube at a position spaced from the base of the tube, with at least a part of the outer periphery of the fuel support platform being joined to the side walls inside the tube, at least one air inlet aperture being provided in a side wall below the fuel support platform, at least one exhaust aperture being provided in a side wall above the fuel support platform, the structure of the sheet of laminate material, the fastening of the side margins of adjacent side walls and the fastening of the outer periphery of the fuel support platform being arranged such that the stove can be collapsed from an operational condition in which the sidewalls define the tube and fuel support platform, to a collapsed, substantially flat condition in which the walls and fuel support platform are substantially parallel.
According to a third aspect of the invention there is provided a portable collapsible solid fuel stove, the stove being formed from sheet laminate material comprising two opposed planar sheets of a metal foil material which together sandwich, and are adhered to, a planar non-metallic substrate, the stove comprising a plurality of oblong walls formed from the sheet laminate material, each wall comprising a pair of side margins, the side margins of adjacent walls being stitched together such that the walls together define a tube one end of which comprises a base which rests in use on the ground and an opposed end of which comprises a mouth to at least partially receive, and support, in use a container or the like, the stove further comprising a fuel support platform also formed from the sheet laminate material, the fuel support platform being located inside the tube at a position spaced from the base of the tube, with the outer periphery of the fuel support platform being stitched to the side walls inside the tube, at least one air inlet aperture being provided in a side wall below the fuel support platform, at least one exhaust aperture being provided in a side wall above the fuel support platform, the structure of the sheet of laminate material, the fastening of the side margins of adjacent side walls and the fastening of the outer periphery of the fuel support platform being arranged such that the stove can be collapsed from an operational condition in which the sidewalls define the tube and fuel support platform, to a collapsed, substantially flat condition in which the walls and fuel support platform are substantially parallel.
The laminate material may be flexible. The fuel support platform may have two opposite sides each of which is attached to one of the side walls. The fuel support platform may be foldable to allow the stove to be collapsed from the operation condition to the collapsed condition.
According to a fourth aspect of the invention there is provided a sheet of laminate material comprising at least one planar sheets of a metal foil material adhered, using fire retardant adhesive, to at least one planar non-metallic substrate, the resulting laminate sheet being fireproof such that the structural integrity of the resulting laminate sheet is stable when subject to flame temperatures of up to 1000° C., the resulting laminate sheet also being flame retardant such that the integrity of the resulting laminate sheet is stable when subject to repeated exposure to flames.
Other aspects of the present invention may include any combination of the features or limitations referred to herein.
The present invention may be carried into practice in various ways, but embodiments will now be described by way of example only with reference to the accompanying drawings.
a and 1b are perspective views of two examples of a sheet of laminate material used to form a portable collapsible stove in accordance with the present invention;
Referring initially to
In a preferred example, the non-metallic substrate 3 comprises a plastic covered glass fibre mat. The substrate 3 may be impregnated and/or coated with PTFE.
The adhesive layers 9, 11 are formed from a single or a composite material including a fire retardant adhesive.
The laminate sheet 1 is thus five-ply in this example.
Referring to
It will be appreciated that the laminate sheet can comprise any number of plies as required to provide the desired flame retardant and structural properties.
In a preferred embodiment, the total thickness of the laminate sheet 1a, 1b is in the range 10 to 500 μm. The thickness of the substrate 3 is in the range 5 to 200 μm. The thickness of the or each aluminium foil sheet 5, 7 is in the range 5 to 200 μm.
The resulting laminate sheet 1a, 1b displays flame retardant properties and will withstand persistent flame temperatures of up to 1000° C. for, for example, 20 to 40 minutes, and still maintain its structural integrity. In the example portable stove described below the exhaust gas temperatures are approximately in the range 200° C. to 400° C.
The resulting laminate sheet 1a, 1b exhibits sufficient rigidity that a container of liquid can be supported by the sheet 1a, 1b without the sheet 1a, 1b deforming, bending or collapsing, when in the form of the expanded stove described below, but is sufficiently flexible that the sheet 1a, 1b can be bent or folded without distorting or deforming as a sheet of aluminium foil would normally do. The sheet 1a, 1b retains these properties under very high operating temperatures as described above.
The introduction of a non-metallic substrate of plastic coated mat 3, and adhesive layers 9, 11, allows the resulting laminate sheet 1 a, 1b to be both structural and articulate in a manner not possible with a metal foil. Thin metal foils normally permanently deform and fatigue when bending occurs, taking the material beyond its ultimate tensile strength by simple deformation pressures and movements. These changes are typically irreversible. The use of the substrate 3 allows the conformal shape of the sheet 1a, 1b to be maintained, and the properties of the metal in a high temperature environment to be exploited.
The laminate material 1a, 1b is therefore flexible, beyond the natural capability of the metal foil on its own. We have used the flexible nature of the resulting laminate material 1a, 1b as part of the advantageous stoves described below.
The laminate material 1a, 1b is capable of significant cycling without fatigue failure. Additionally, because of the cycling through the high temperatures endured during use, we have determined that the heat cycling adds a stress relieving aspect to the sheet 1a, 1b, preventing work hardening by normalising the aluminium material each time the stove is used. The sheet 1a, 1b therefore remains more flexible than would be expected from a cold worked metal material when repeatedly folded.
Referring additionally to
The stove 13, in this example, comprises six planar oblong side walls 15 of the laminate sheet. The side margins of each side walls 15 are bent beyond 90° relative to the plane of each side wall 15, and each side margin is fastened to the adjacent side margin of the adjacent side wall 15 to form radially outwardly projecting fins 18. The side margins are fastened together using fire retardant stitching 19. Stitching 19 uses, in this example, a high temperature resistant PTFE coated thread formed from glass fibre. The thread may also be impregnated or coated with Graphite to render the thread low visibility.
The top and base margins 21, 23 of each side wall 15 are also stitched 25, 27 respectively to resist delamination of the laminate sheet in use.
When so fastened, the side walls 15 together define an upstanding fire resistant, high temperature resistant tube 29 one end of which functions as a base 31 which rests in use on the ground, and the opposite end of which defines a mouth 33 into which a container (not shown) is placed in use of the stove 1. One of the side walls 15A is provided with an oblong cut-out 35 to receive a handle of the container. Because the side walls 15 are formed from the laminate sheet, the side walls 15 can to some extent flex around, and conform to, the shape of the container such that the side walls 15 snugly engage the container to resist air flow between the side walls 15 and the container. The structure of the laminate sheet, and the resulting tube structure, provides sufficient strength and rigidity in compression, and resistance to bending and folding, to support the container when filled with liquid.
The stove 13 further comprises a fuel support platform 41 formed from the laminate sheet and being of generally hexagonal shape when viewed in plan, to match the generally hexagonal cross section of the tube 29, as defined by the six side walls 15. The periphery of the fuel support platform 41 is fastened to the side walls 15 inside the tube 29 by fire retardant stitching 43 as described above. The fuel support platform 41 is inclined inside the tube 29 such that the part of the platform 41 beneath the cut-out 35 is higher up the tube 29 than the opposed part of the platform 41 fastened to side wall 15B.
The fuel support platform 41 is spaced from the base 31 of the tube 29 and in this example is located about a quarter of the way up the tube 29. An air inlet manifold 51 is therefore defined between the ground on which the tube 29 rests in use, and the underside of the fuel support platform 41. The air inlet manifold 51 is provided with two external air inlet apertures 53 formed in opposed side walls 15C, 15D. The fuel support platform is itself provided with two internal air inlet apertures 55. The air inlet apertures 53, 55 form a controlled air inlet path to the region above the fuel support platform 41, that is, the region in which the fuel is placed in use.
The stove 13 is further provided with four exhaust gas outlet apertures 57, located above the fuel support platform 41. When the container is sealingly located in the mouth 33 of the tube 29, a fixed volume combustion chamber is defined between the underside of the container and the top of the fuel support platform 41 from which exhaust gas can only exit via the exhaust gas outlet apertures 57.
An access aperture 60 with closing tab 61 is provided on side wall 15b and this is used to allow a suitable ignition source, such as a match or lighter, access to the combustion chamber 59.
A tab 63 is provided on the underside of the fuel support platform 41 and this can be pulled to help expand the stove 13 from the collapsed condition described below.
With particular reference to
To expand the stove 13, opposed side walls 15, or opposed fins 18 can be gripped and pulled apart to expand the stove 1 from the collapsed, substantially flat, condition, to the expanded, substantially tubular condition. The tab 63 on the underside of the fuel support platform 41 may also be pulled downwardly to pull the fuel support platform 41 from a folded condition, to a planar condition. When in the expanded condition, the stove 13 is self supporting with the base 31 of the tube 29 resting on the ground, and the fuel support platform 41 acting as a brace across the tube 29 to resist bending or folding of sidewalls 15.
When in the expanded condition, and with reference also to
Once the fuel is ignited, or before the fuel is ignited, the container is placed into the mouth 33 of the tube 39 and this defines the fixed volume combustion chamber 59.
Exhaust from the combustion process, as indicated by arrow E, exits the combustion chamber 59 in a controlled manner via exhaust outlet apertures 57. Again, the volume of the combustion chamber 59, and the size, shape, location and number of exhaust outlet apertures 57 may be calculated to provide the required burn characteristics. Heat rises onto the container as per arrow H.
Referring additionally to
Modified stove 63 further comprises low visibility features which render the stove 63 more difficult to see both during transit, and in use. Being of low visibility is a useful feature particular in military applications where the user of the stove may not wish to give away their position. Ordinarily the flames and glow from the burning fuel may be visible through the exhaust apertures 57. Furthermore, the aluminium foil of the sheets 1 of laminate material 1 would reflect any ambient or directed light.
Thus, the sheet of laminate material 1 of stove 63 comprises an additional anti-reflective coating on the external surfaces of the aluminium foil sheets 5, 7. The anti-reflective coating may comprise a matt black coating for example. The modified laminate sheet is thus seven-ply in this example.
Additionally, the stove 63 comprise aperture shields 65 each of which extends from the base 31 of the tube 29 towards the mouth 33 of the tube 29. Each aperture shield 65 comprises a flow channel 66 defined by an outer, oblong flap 67 having pleated sides 69 which extend between the side margins of the flap 67 and a respective side wall 15 of the stove 63. The bottom of each flap 67 is fastened adjacent the base 31 of tube 29. The top of each flap 67 is not fastened to the side walls 15 and is provided with a pull tab 71 to enable the top of each flap 67 to be pulled away from the respective side wall 15. When so pulled, with reference to
With particular reference to
With reference to
A thermally insulated tab or the like may be provided on each flap 67 to enable the flap 67 to be gripped once the stove 63 has been used, to enable the flap 67 to be pushed to the collapsed condition. This may be advantageous should the stove 63 need to be packed away relatively quickly after use, without burning the user's hands or fingers. The tab may be provided at the top margin of each flap 67.
A tab or clasp or other retainer may be provided at the top of each flap 67 to engage with the top of the respective side wall 15 to prevent the flap 67 opening inadvertently when in the collapsed condition.
It will be appreciated that any number of side walls 15, inlet apertures 53, 55 and exhaust apertures 57 may be provided as required.
Each fin 18 may be provided with a reinforcing element or elements to provide additional structural strength to each fin 18. The reinforcing element may comprise a strip of reinforcing material received within a pocket defined by the fin 18. The reinforcing material may comprise a fold of material folded around the fin 18 or over the top of the fin 18. The reinforcing material may comprise a metal material such as a tempered aluminium material for example.
It is preferred that the stove 13, 63 uses a solid fuel. An example of a solid fuel used historically is Hexamine although other fuel types are envisaged.
The stove 13, 63 may also or alternatively be used with gel fuels, ie jelly like fuels which are typically ethanol based, or liquid fuel stored in a container which can be placed on the fuel support platform 41. The stove 13, 63 may also or alternatively use gas or vaporised fuels (such as petrol, paraffin, butane or propane).
With reference to
With reference to
With reference to
With reference to
Number | Date | Country | Kind |
---|---|---|---|
0523234.3 | Nov 2005 | GB | national |
1200251.5 | Jan 2012 | GB | national |
Number | Date | Country | |
---|---|---|---|
Parent | 12093701 | Sep 2008 | US |
Child | 13736774 | US |