RELATED APPLICATIONS

[0001] The present application claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Application 61/916,160 filed on December 14, 2013, the disclosure of which is incorporated herein by reference.

FIELD

[0002] Embodiments of the invention relate to providing a portable camping stove that burns solid fuel.

BACKGROUND

[0003] Portable camping stoves have been in use for close to two centuries, for outdoor cooking and heating of food and water usually during camping, traveling and picnicking. Portable camping stoves vary in their shapes and are designed to be lightweight, easily carried, and/or packed, and may be designed to burn gas, liquid or solid fuel. Solid fuel camping stoves may use various types of fuel ranging from natural resources such as branches, wood, or coal, and fuel tablets. The stove typically comprises an open bin in which the solid fuel is burned, and a metal grill that fits on the bin and on which a cooking utensil that holds food or water to be heated is placed.

SUMMARY

[0004] An aspect of an embodiment of the invention relates to providing a portable camping stove for cooking and heating that burns solid fuel. The stove comprises features that may enhance efficiency of fuel combustion and reduce smoke emission. Optionally the stove is collapsible and easily packed in a case for carrying and packing.

[0005] In an embodiment of the invention, the stove comprises a combustion chamber which has a longitudinal axis and is enclosed by a combustion chamber wall supported by a housing, and a bellows for generating airflow through the combustion chamber. The combustion chamber wall is optionally circularly cylindrical having an axis of rotation substantially coincident with the longitudinal axis, a closed end, and an open end through which fuel may continually be loaded into the chamber. A longitudinal opening, hereinafter also referred to as a smoke vent, parallel to the axis of rotation is formed at a top of the combustion chamber and allows combustion gases to escape from the combustion chamber. Liquid such as coffee or soup to be heated by the stove, or food to be cooked on the stove, is supported by a grill placed over the smoke vent or by support tabs extending from edges of the vent. In an embodiment of the invention, the bellows is shaped as a relatively flat rectangular box that may conveniently be carried in a pocket of a shirt or vest. Optionally, the bellows comprises an USB (universal serial bus) socket to allow charging of various portable devices such as smartphones and iPads, digital cameras etc.

[0006] In an embodiment of the invention, the housing may be formed from interlocking panels configured to support the combustion chamber with the combustion chamber axis of rotation oriented substantially parallel to a surface on which the housing rests. The combustion chamber walls and panels of the housing form an airway passage between them through which air driven by the bellows flows to the combustion chamber. Air driven by the bellows exits the bellows via an air output aperture and enters the airway passage through an input aperture formed in the housing optionally adjacent to the closed end of the combustion chamber. Air inlet holes formed in the combustion chamber wall allow air flow from the airway passage into the combustion chamber. In an embodiment of the invention a total sum of the aperture areas of the inlet holes is substantially equal to an area of the air output aperture of the bellows. As a result, the bellows operates relatively efficiently and substantially all the air driven out of the bellows enters the combustion chamber.

[0007] In an embodiment of the invention, the airway passage and inlet holes are configured so that a portion of the air flowing in the airway passage from the bellows to the combustion chamber contacts an outside surface of the combustion chamber and is preheated before entering the combustion chamber. The preheated air improves efficiency of combustion in the combustion chamber, completeness of combustion, and reduces smoke from the combustion chamber released into the air.

[0008] Optionally, the inlet holes are configured having inlet holes along a bottom of the combustion chamber opposite the smoke vent through which combustion gases exit the combustion chamber and along and near edges of the smoke vent. The inlet holes may be configured in rows parallel to the axis of rotation of the combustion chamber. Optionally, the inlet holes are configured so that an amount of the air from the bellows that enters the bottom of the combustion chamber is greater than an amount of the air that enters the combustion chamber along the edges of the smoke vent.

[0009] According to an aspect of an embodiment of the invention the stove is configured as a modular/collapsible stove comprising modular components that may relatively easily be assembled to provide the combustion chamber and housing supporting the combustion chamber. The combustion chamber and housing may readily be disassembled for ease of carrying and packing the stove. In an embodiment, the modular stove comprises a set of panels configured with tongues and/or slots that interlock with each other by fitting a tongue of a panel into a matching slot of another panel for relatively easy assembly of the panels to form the combustion chamber and housing of the stove.

[0010] By way of example, in an embodiment of the invention, a plurality of curved panels interlock with each other to form a substantially circularly cylindrical combustion chamber. Optionally two side panels, a bottom panel, a back panel configured with an input aperture, and a front panel interlock to form the housing that supports the combustion chamber. The circularly cylindrical combustion chamber may be mounted to and supported by the support housing by inserting ends of the combustion chamber into circular holes in the front and back panels of the housing.

[0011] There is therefore provided in accordance with an embodiment of the invention, a portable camping stove for burning solid fuel comprising: a combustion chamber having a wall, a closed end, an open end, a longitudinal axis extending between the ends, inlet holes for air to enter the combustion chamber and a longitudinal opening substantially parallel to the longitudinal axis at a top of the stove for escape of combustion gases; a housing that supports the combustion chamber on a surface on which the stove may be placed with the longitudinal axis substantially parallel to the surface and forms together with the combustion chamber wall an airway passage from which air exits via the inlet holes in the combustion chamber and air enters via an inlet aperture formed in the housing. Optionally the inlet aperture is formed adjacent the closed end of the combustion chamber. In an embodiment the camping stove comprises a bellows configured to blow air into the inlet aperture.

[0012] Optionally, the opening at the top is delimited by two edges parallel to the longitudinal axis. Additionally or alternatively, the airway passage may extend substantially the length of the combustion chamber along the longitudinal axis.

[0013] In an embodiment of the invention, the combustion chamber wall is cylindrical.

Optionally, the combustion chamber wall is substantially circularly cylindrical having an axis of rotation coincident with the longitudinal axis of the combustion chamber. Optionally, the airway passage has a cross section perpendicular to the longitudinal axis that is substantially congruent to an area between a trapezoid and a portion of an area of circle having a diameter substantially equal to an outer diameter of the combustion chamber wall.

[0014] In an embodiment of the invention, in a plane perpendicular to the longitudinal axis the longitudinal opening subtends an angle less or equal to about 180° at the axis. Optionally, the longitudinal opening subtends an angle less or equal to about 120° at the axis.

[0015] In an embodiment of the invention, the inlet holes comprise at least one line of holes parallel to the longitudinal axis. Optionally, the at least one line of holes comprises a plurality of lines of holes. Additionally or alternatively, the at least one line of holes may comprise a line of holes opposite the longitudinal opening in the combustion chamber.

[0016] In an embodiment of the invention, the bellows comprises a parallelepiped shaped housing having two relatively large parallel face surfaces and relatively narrow edge surfaces perpendicular to the face surfaces. Optionally, the parallelepiped is a rectangular parallelepiped.

[0017] Additionally or alternatively, the camping stove comprises a centrifugal fan that draws air into the housing through a bellows inlet aperture located on one of the face surfaces and drives the drawn-in air out of the bellows through an edge surface. Optionally, the camping stove comprises a flap rotatable between a first closed position in which it covers the bellows inlet aperture and a second, open position in which it does not cover the bellows inlet aperture. Optionally, in the open position the flap is angled at an acute angle with respect to the face surface in which the bellows inlet aperture is located.

[0018] In the discussion, unless otherwise stated, adjectives such as "substantially" and "about" modifying a condition or relationship characteristic of a feature or features of an embodiment of the invention, are understood to mean that the condition or characteristic is defined to within tolerances that are acceptable for operation of the embodiment for an application for which it is intended. Unless otherwise indicated, the word "or" in the description and claims is considered to be the inclusive "or" rather than the exclusive or, and indicates at least one of, or any combination of items it conjoins.

[0019] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF FIGURES

[0020] Non-limiting examples of embodiments of the invention are described below with reference to figures attached hereto that are listed following this paragraph. Identical features that appear in more than one figure are generally labeled with a same label in all the figures in which they appear. A label labeling an icon representing a given feature of an embodiment of the invention in a figure may be used to reference the given feature. Dimensions of features shown in the figures are chosen for convenience and clarity of presentation and are not necessarily shown to scale.

[0021] Fig. 1A schematically shows a perspective view of a camping stove comprising a combustion chamber seated in a "trapezoidal" housing, in accordance with an embodiment of the invention;

[0022] Fig. IB schematically shows another perspective view of the camping stove shown in Fig. 1A, in accordance with an embodiment of the invention;

[0023] Fig. 1C schematically shows a perspective cutaway view of the camping stove shown in Figs. 1A and IB, in accordance with an embodiment of the invention;

[0024] Fig. 2 schematically shows a perspective view of a bellows, in accordance with an embodiment of the invention;

[0025] Fig. 3A-3B schematically illustrate assembling the bellows to the housing, in accordance with an embodiment of the invention;

[0026] Fig. 3C schematically shows a perspective view of the bellows and a smartphone to be connected to the bellows for charging, in accordance with an embodiment of the invention;

[0027] Fig. 4 schematically shows the stove comprising components shown in the previous figures, having a pot placed over a smoke vent, and burning wood sticks loaded in the combustion chamber, in accordance with an embodiment of the invention; and

[0028] Figs. 5A-5B schematically show components of a modular collapsible stove, and a case for packing and carrying the modular stove respectively, in accordance with an embodiment of the invention; and

[0029] Fig. 5C schematically shows an exploded view of the modular stove, in accordance with an embodiment of the invention. DETAILED DESCRIPTION

[0030] In the following detailed description, a camping stove in accordance with an embodiment of the invention comprising a combustion chamber supported by, and seated in a trapezoidal housing is described with reference to Figs. 1A, IB, and 1C. A bellows that couples to the housing to force air into the combustion chamber is described with reference to Fig. 2, in accordance with an embodiment of the invention. Engagement of the bellows to the housing is schematically illustrated and discussed with reference to Figs. 3A and 3B. The flow of air driven through the airway inlet aperture into the airway passage and into the combustion chamber by the bellows is described with reference to Figs. 1C, Fig. 4 schematically shows the stove having a cooking pot placed on its top and burning wood logs in the combustion chamber, to heat food or liquid in the cooking pot. A bellows in accordance with an embodiment of the invention having an USB socket for charging portable devices such as smartphones, iPads, and digital cameras is discussed with reference to Fig. 3C. A collapsible, modular stove which may easily be disassembled, packed and carried is schematically shown and discussed with reference to Figs.5A-5C.

[0031] Figs. 1A and IB schematically show different perspective views of a stove 100 having a combustion chamber 101 supported by a housing 102, in accordance with an embodiment of the invention. The combustion chamber has an axis of rotation indicated by a dashed line 50, and comprises an optionally substantially circularly cylindrical wall 10, on which solid fuel may be placed for combustion (as shown in Fig. 4) to heat food and/or water. Wall 10 is formed having top and bottom air inlet holes 15 and 16 respectively, and has an open end 11 through which solid fuel, such as wood sticks and branches 104 (fig. 4) may be fed into the combustion chamber, and a closed end closed by a back wall 20. A longitudinal opening 13 at a top of the combustion chamber allows gases formed by combustion of fuel in combustion chamber 101, to escape from the combustion chamber. Fig. 4 schematically shows how the burning wood sticks loaded into combustion chamber 101 of stove 100 may be continually pushed into the combustion chamber as they are consumed by fire flames 105 emerging from the burning sticks.

[0032] Reverting to Figs. 1A and IB, housing 102 optionally has a trapezoidal cross section , and comprises sloping side panels 31 (Fig. 1A) and 32 (Fig. IB), a front panel 40, a back panel 60, (Fig. IB) and a base panel 61 (Fig. IB), in accordance with an embodiment of the invention. Sloping panels 31 and 32 optionally have extensions 35 and 36, also referred to as "support tabs" configured for supporting a cooking vessel such as a pot 103, as shown in Fig. 4. In an embodiment of the invention, wall 10 of combustion chamber 101 and panels 31, 32, 40, 60 and 61 that form housing 102 delimit and enclose an airway passage 30 schematically shown in a cutaway perspective view of camping stove 100, in Fig. 1C. Back panel 60 is formed having an input aperture 14 (also shown in Fig. IB) through which air may be forced into airway passage 30 to flow into combustion chamber 101 via air inlet holes 15 and 16. Flow arrows 203-206 (Fig. 1C) schematically indicate flow patterns of air forced through input aperture 14 into airway passage 30.

[0033] In an embodiment of the invention input aperture 14 is rectangular, and shaped to receive a matching air output aperture 212 of a bellows 200, schematically shown in Fig. 2, that forces air into airway passage 30. In an embodiment of the invention, bellows 200 comprises a flat rectangular "parallelepiped" housing 220 optionally having a size which may relatively easily be carried in a clothing pocket. Bellows 200 optionally comprises a centrifugal fan 210 and a flap 211 that may be rotated between closed and open positions. When closed, flap 211 covers and protects fan 210. When open, flap 211 exposes centrifugal fan 210 so that when rotating it may draw air into bellows 200 along a direction indicated by a block arrow 201 and drive the drawn- in-air out of the bellows along a direction indicated by an arrow 202 via air output aperture 212 (- Fig 2). In an embodiment of the invention, the flap is oriented at an acute angle relative to a top surface 217 of housing 220 and when knocked sufficiently hard, for example by a stone, debris, or a coal from the combustion chamber, closes to protect fan 210 from damage. Housing 220 comprises a power source (not shown), optionally a rechargeable battery, for powering centrifugal fan 210, and a switch optionally located on an edge surface 214 (Fig. 3 A discussed below) of housing 220 for connecting and disconnecting the fan to the power supply to turn on and turn off the fan respectively. A charging socket 216 is provided for charging the rechargeable power source, and a status light 219 indicates whether fan 210 is turned on or turned off. The power source may be charged by a car charger plugged into a cigarette lighter socket of a car. Optionally, power source is a portable solar charger.

[0034] Bellows 200 is coupled to camping stove 100 by inserting air output aperture 212 of the bellows into input aperture 14 of the camping stove so that housing 220 of bellows 200 rests on bellows support panel 28 and butts up against stop tab 29 (schematically shown in Figs. IB and 3A). Figs 3A and 3B schematically show coupling bellows 200 to camping stove 100.

[0035] Stove 100 may be operated by lifting flap 211 to uncover the fan and turning on a switch 213 to start rotation of the fan. The open position of flap 211 of the housing enables air to be directed to the fan as indicated by arrow 201. Air accelerated by turning blades 215 of the fan, exits bellows 200 through air output aperture 212 to enter airway passage 30 via input aperture 14.The air entering passage 30 flows in various directions in the airway passage (arrows 203-206) and is preheated prior to entering combustion chamber 101 by contact with the walls of combustion chamber 101. The preheated air in airway passage 30 flows through top and bottom air inlet holes 15 and 16 in directions indicated by arrows 207 and arrows 208, respectively. The preheated air operates to improve efficiency or completeness of combustion of fuel in the combustion chamber.

[0036] In an embodiment of the invention, smoke vent 13 subtends an angle of less than about

180° at the axis of rotation. Optionally, the subtended angle is less or equal to about 120°. As the subtended angle decreases, a dwell time of hot gases in combustion chamber 101 increases and may improve completeness of combustion of fuel in the combustion chamber.

[0037] In an embodiment of the invention a total sum of aperture areas of top and bottom air inlet holes 15 and 16 is substantially equal to a surface area of air output aperture 212 of bellows 200. A volume of air, driven out of the bellows and into the airway passage at any given time, is about equal to a volume of air flowing through air inlet holes 15 and 16 and into combustion chamber 101.

[0038] In an embodiment of the invention, air inlet holes 15 and 16 are arranged optionally in rows parallel to axis of rotation 50, as schematically shown in the Figs. 1C, and 3A-3B. At least one bottom row (only one row is visible in figs. lA-lC) of air inlet holes is located at a bottom region 9 of combustion chamber wall 10 and at least one row (only one row is visible in Figs. 1 A and 1C) of top inlet holes 15 is formed along each edge 8 of wall 10. Optionally bottom air inlet holes 15 are larger relative to top air inlet holes 16. A ratio of a sum of the areas of large bottom inlet holes 16 relative to a sum of areas of small top inlet holes 15 is optionally 3 to 1. When air flows through airway passage 30, a greater volume of the air may enter the combustion chamber through the bottom inlet holes and into the combusting fuel. A smaller volume of air flows upwards in airway passage 30, which optionally as schematically shown in Fig. 1C, narrows towards the small top inlet holes. Air flowing towards top inlet holes 15 is therefore efficiently heated by close contact with wall 10 of combustion chamber 101 before entering the combustion chamber through top inlet holes 15 and contributes to completion of burning of combustion material in the flue gas and a reduction of smoke emission. [0039] Whereas the description above describes top and bottom air inlet holes configured and arranged in rows, embodiments of the invention may have other configurations of air inlet holes. For example, the holes may be elongated, triangular, or irregular, and optionally randomly located on combustion chamber wall 10.

[0040] In an embodiment of the invention, the combustion chamber and the housing are made of metal, such as iron and steel and/or any material that may be known or used in the art. Joining walls and panels of the combustion chamber and the housing (the various walls and panels described in the previous paragraph) is done optionally by welding and/or any other method used and/or known in the art. Folding tongues of various sizes and shapes configured in walls and panels of combustion chamber 101 and/or housing 102 may be folded over and welded with walls and panels of housing 102 and combustion chamber 101. By way of example, folding tongues 41 extending out of front panel 40 are folded over and welded to wall 10 (fig. 1A). Similarly, folding tongs 42 and 62 of front and back panels 40 and 60 respectively fold over and are welded to sloping side panels 31 and 32, folding tongues 33 and 34 of sloping panels 31 and 32 respectively are folded over and adhered optionally by welding to wall 10.

[0041] Whereas the description above describes folding tongues formed in walls and panels of combustion chamber 101 and housing 102, embodiments of the invention are not limited to a stove comprising panels and walls with such configurations, and other configurations are possible.

[0042] Additionally and as schematically shown in figure 3C, bellows 200 may comprise an USB socket 230 formed to receive a matching USB plug end, for charging a portable USB chargeable device in accordance with an embodiment of the invention. The USB socket optionally formed on surface 214, may be particularly useful for charging an appliance, such as a smartphone 240 shown in Fig. 3C when in the outdoors on camping trip. For example, if smartphone 240 is running low on power, it may be at least partially recharged by plugging the smartphone into bellows 200 using a cable 235 having an USB plug end 231 matching USB socket 230 of the bellows, and a plug end 232 matching a socket (not shown) formed in smartphone 240. It is noted that the USB socket may be located on surfaces of the bellows and that whereas the figures illustrate a smartphone 240 to be charged using the bellows, other USB chargeable devices may be plugged into the USB bellows socket 230 such as digital cameras, iPads and the like. [0043] Figs. 5A-5C, schematically show a collapsible "modular" camping stove 300, in accordance with an embodiment of the invention. The components of the collapsible stove are schematically shown in Fig. 5A stacked and packed in a case 400 for convenient carrying of the modular stove. Features of modular stove 300 described below resemble features of stove 100 described in previous paragraphs, and stove 300 is optionally assembled and constructed to operate with a bellows similar to bellows 200 described above.

[0044] As schematically shown in Fig. 5B, modular stove 300 comprises components that may be assemble to create a combustion chamber 301 and a housing 302 similar to combustion chamber 101 and housing 102 of camping stove 100 (Figs. 1A and IB). Combustion chamber

301 comprises a back wall 320 and optionally three slats 311, 312, 313 which when assembled form a combustion chamber wall (not shown) resembling combustion chamber wall 10, described above. Housing 302 is assembled to form optionally a trapezoidal supporting structure for combustion chamber 301, which is similar to trapezoidal housing 102 of stove 100. Housing

302 comprises a front panel 340, a back panel 360 having optionally a rectangular input aperture 314 (Fig. 5C) configured to accept and receive air output from aperture 212 of bellows 200 described above, sloping side panels 331 and 332 (Fig. 5C) formed with support tabs 335 and 336, respectively, for supporting a cooking vessel, and a bottom base panel 361 (Fig. 5C).

[0045] Fig. 5C schematically shows an exploded view of the various elements of stove 300, in which the position of the various elements are shown prior to their assembly, in accordance with an embodiment of the invention. The various elements are formed with slots and/or tongues which interlock by receiving matching tongues and/or fitting into matching slots of another element. By way of examples, tongues 333 configured in bottom panel 361 fit into slots 338 (Fig. 5B) of the sloping side panels, tongues 339 of the sloping side panels fit and interlock into slots 341 of front panel 340 (figs. 5B-5C). Similarly, slat 311 is formed with tongues 315 which interlock with matching slots 316 of slat 312, slat 313 is formed with tongues 319 which interlock with matching slots 317 of slat 312 - to form a relatively circularly cylindrical chamber wall which is assembled with back wall 320, and then seated in housing 302.

[0046] Additional folding tongues which may be formed at the edges of the various panels comprised in housing 302 fold over walls of combustion chamber 301 providing additional support when assembled. By way of example, slats 311-313 forming the chamber wall are supported by tongues 321-323, respectively of back wall 320. Tongues 342, 343 and 344 (Fig. 5B) formed in front panel 340 fold over sloping side panels 331, 332 and bottom panel 361, respectively. Similarly, folding tongues 362, 363 and 364 (Fig. 5B) formed in back panel 360 fold over sloping side panels 331, 332 and bottom panel 361, respectively.

[0047] Whereas the modular stove is described and shown to comprise various elements formed with tongues and slots which interlock and construct stove 300, and folding tongues formed in panels of housing 302 optionally for additional support, embodiments of the invention are not limited to those configurations and other configurations and/or methods for the assembly of the various elements are possible. By way of example, elements formed with matching through holes may be joined by inserting screw or split pins into matched-up holes.

[0048] Additionally, the modular stove is not limited to a particular number of elements constructing combustion 301 chamber and housing 302, and more or less elements are possible. By way of exmpale, it is possible to construct the combustion chamber wall with more than three slats.

[0049] In the description and claims of the present application, each of the verbs, "comprise" "include" and "have", and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of components, elements or parts of the subject or subjects of the verb.

[0050] Descriptions of embodiments of the invention in the present application are provided by way of example and are not intended to limit the scope of the invention. The described embodiments comprise different features, not all of which are required in all embodiments of the invention. Some embodiments utilize only some of the features or possible combinations of the features. Variations of embodiments of the invention that are described, and embodiments of the invention comprising different combinations of features noted in the described embodiments, will occur to persons of the art. The scope of the invention is limited only by the claims.