WO2015108425A1

WO2015108425A1 - Stove

Info

Publication number: WO2015108425A1
Application number: PCT/NO2015/050010
Authority: WO
Inventors: Christopher Kavanagh; Christian ABRY; Ole SÆTHRE; Emil Abry
Original assignee: Safi International
Priority date: 2014-01-17
Filing date: 2015-01-16
Publication date: 2015-07-23

Abstract

Present invention relates to a stove (1) for burning liquid alcohol, preferably ethanol, methanol or a mixture of these, comprising one or more burners (18) for generating flames from fuel supplied from container(s) (7), said stove (1) having support(s) (19) atop the burner(s) (18) for supporting cookware, wherein said the burner(s) (18) are comprised of a largely vertically arranged burner tube (18a) atop a baseplate (18e), said baseplate (18e) equipped with two or more apertures (18f) and arranged above fuel container (7) with a vertical separation distance of 2-7mm.

Description

STOVE

FIELD OF THE INVENTION

The present invention in general, relates to the technical field of stoves that can generate a flame from a fuel such as for example liquid alcohol and the like.

Particularly, the present invention relates to a cooking stove with an improved design that ensures a substantially high burning efficiency, low emission level and also easy and quick loading and unloading of fuel.

More particularly, the present invention relates to a cooking stove that can generate a flame from a fuel according to the preamble of claim 1

TECHNICAL BACKGROUND OF THE INVENTION

Cooking stoves, which generate flame by burning of a fuel such as liquid alcohol are well known. It is of immense importance that these stoves should have adequate burning efficiency for ensuring good quality of the cooked food. Furthermore, the emission levels must be low for preventing environmental pollution. Further, it is important that substantial amount of fuel should not spill out while cooking as such an eventuality is highly accident prone and also leads to environmental hazards. Additionally, to ensure that there is no hindrance during cooking, the refueling process has to be convenient and brisk as well.

With regard to the above aspects, several designs of such cooking stoves have been proposed.

Publication no. WO 2008/058566 discloses a cooking stove in which the distance between the burner and the cookware ensures a proper emission level of carbon monoxide and also ensures high burning efficiency. This arrangement does not appear to be perfect in as much as, it may not be always possible to maintain this distance in practice. Published US patent application US2010/0192933 discloses an alcohol stove that has a heating wire located above the opening of the fuel container. When the heating wire is connected to an electrical power source, it^'s radiated heat causes fuel inside the container to vaporize. The fumes are then ignited as they pass the heating wire and the alcohol stove gets ignited.

The arrangement disclosed in US2010/0192933 also does not appear to be perfect, in respect of providing maximum burning efficiency and ensuring low emission level. That apart, the arrangement of the stove requires that it be turned upside down in order for the fuel containers to be removed. This is a disadvantage in that the pot holder must come in contact with the kitchen bench/ floor etc. while it is still hot from previous cooking. In addition, there is potential for spillage of fuel from the container while it is loaded upside down. Thus, it is impossible for this arrangement to be refueled conveniently and briskly to ensure that the cooking process is not hindered.

In brief, cooking stoves known in the art, which function by burning of fuel such as liquid alcohol, do not teach high burning efficiency, low emission level, and convenient and quick refueling technology.

The cooking stove according to the present invention meets this need of ensuring high burning efficiency, low emission levels, and convenient and quick refueling technology. This is achieved by the cooking stove of the present invention by virtue of its improved burner design and specially constructed fuel containing containers. That apart, by virtue of the stove design, these containers can be easily and quickly reloaded or unloaded to and from the front/back side of the stove.

The cooking stove of the present invention, by virtue of its unique design meets other associated needs as well, as will be clear from the following description.

OBJECTS OF THE INVENTION It is the prime object of the present invention to provide a cooking stove that can generate a flame by burning a fuel such as a liquid alcohol or mixtures thereof and the like, which ensures substantially high burning efficiency, low emission level and easy and quick loading and reloading of fuel containing containers.

It is another object of the present invention to provide a cooking stove that can generate a flame by burning a fuel such as a liquid alcohol or mixtures thereof and the like, which prevents spilling of food through the air ventilations during cooking. It is yet another object of the present invention to provide a cooking stove that ensures that the fuel containing containers remain firmly locked during cooking.

All through the specification including the claims, the words "fuel"," containers", "containers", "flame", "cookware", "butterfly valve", "stopper", "regulator", "lock", "burners", "burner tubes" are to be interpreted in the broadest sense of the respective terms and includes all similar items in the field known by other terms, as may be clear to persons skilled in the art.

Restriction/limitation, if any, referred to in the specification, is solely by way of example and understanding the present invention.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a stove for burning liquid alcohol, preferably ethanol, methanol or a mixture of these, comprising one or more burners for generating flames from fuel supplied from container(s), said stove (1 ) having support(s) atop the burner(s) for supporting cookware, said stove is characterised in that the burner(s) are comprised of a largely vertically arranged burner tube atop a baseplate, said baseplate equipped with two or more apertures and arranged above the fuel container with a vertical separation distance of 2-7mm. Preferably, the combined area of the apertures in the baseplate comprises 5-20% of the area of the central opening in container .

In addition, the burner tube has preferably an integrated flame spreader and two or more flame outlets at its upper part.

Further, it is preferred that the apertures are equipped with flap details along one or more edges. In another embodiment of the invention, the burners have burner tubes provided with secondary air intakes for a second burning of the fuel and primary air is supplied through the bottom portion of the burner tubes.

The flow of primary air and fuel vapor through the burner tubes can preferably be regulated depending upon the flame required.

The fuel container houses preferably a mineral wool component.

The fuel containing containers are preferably slidably loadable and removable to and from the stove along its front/side/rear portion.

Preferably, the containers are equipped with flanges which glide on rails .

Further it is preferred that the containers can be replaced and loaded with the stove still operative. That is to say that one fuel container (extinguished) may be removed and refilled while the other burner is still in use (in a stove equipped with 2 burners.)

Each container is preferably provided with a removable lid at its top portion to allow replacement of its contents.

The container may be equipped with alternate removable lids each lid having a central opening of a differing diameter thus altering the energy output of the container. The containers preferably remain firmly locked in the lower portion of the stove during burning by means of a locking means, which is actuated once the regulator of the stove is put on for burning and unlocks automatically once the regulator (14) is put off to stop the burner . Each container has preferably a low central bottom with sloping base for enabling the flow of fuel towards the middle portion of the container, such that the fuel is effectively drawn through the wick material.

In a preferred embodiment, each burner is equipped with multiple burner tubes.

The body of the stove is preferably of a torsion box construction type for making it light and inexpensive, air apertures are provided along the underside of the body of the stove for protection against spillage of food there, and the stove has an open, bridge-like construction.

The stove is preferably constructed from a chassis housing one or more subassemblies comprising one burner, one heatshield, one regulator assembly and one fuel container.

BRIEF DESCRIPTION OF THE DRAWINGS

Having described the main features of the invention above, a more detailed and non-limiting description of an exemplary embodiment is given below, with reference to the drawings.

Figurel is a perspective view of the stove according to the first preferred embodiment of the present invention described.

Figure 2 is a perspective view of the stove shown in figure 1 with one container taken out. Figure 3 is view of the bottom portion of the stove shown in figure 1 , without the containers and with the burners partly open.

Figure 4 is a cross sectional view of the stove shown in figure 1 , sectioned front to back through the centre of one burner.

Figure 5 is a perspective view of the stove shown in figure 1 with the top portion removed to show the details of the regulator and the locking mechanism. Figure 6 is an exploded view of the container applied in the stove shown in figure 1 .

Figure 7 is a view of the top portion of the container. Figure 8 is a cross-sectional view of the container shown in figure 7 along the line A-A.

Figure 9 is a perspective view of the burner applied in the stove shown in figure 1 .

Figure 10 is a view of the top portion of the burner shown in figure 1 .

Figure 1 1 is a cross-sectional view of the burner shown in figure 10 along the line A-A.

Figure 12 is an enlarged view of the windshield assembled to the stove shown in figure 1 .

Figures 13 and 14 are perspective views showing two different alternative embodiments of the burner, seen from above and beneath, respectively.

Figure 15 is a perspective view of an alternative embodiment of the heatshield subassembly. Figure 16 is a cross-sectional view through the alternative embodiment of Figure 15 along a plane centred through the burner and from the front to the rear of the stove. Figure 17 is an exploded view of an alternate embodiment of the burner. DETAILED DESCRIPTION OF THE INVENTION

The following describes a preferred embodiment of the present invention which is exemplary for the sake of understanding the invention and non-limiting.

In all the figures, like reference numerals represent like features. Further, when in the following it is referred to "top", "bottom", "upward", "downward", "above" or "below" , "right" or "left" "front" or "side" and similar terms , this is strictly referring to an orientation with reference to the figure 1 , where the "top" is the top portion of figure 1 .

It should also be understood that the shape and orientation of the various components might be otherwise than shown in the drawings, without deviating from the principle of the invention. The number of components may also vary other than what is illustrated and disclosed herein and this is within the scope of the present invention. For example, there may be more containers rather than two as shown and described. Similarly, there may be more or less than four burner tubes in each burner. All these variations are within the scope of the present invention.

Further, for the sake of understanding, the fuel mentioned is liquid alcohol. Liquid alcohol includes ethanol and/or methanol with for example say around 90% concentration. It is within the scope of the present invention that the fuel may include similar such substances as known to persons skilled in the art and all these fall within the ambit of the present invention.

Figure 1 is a perspective view of the stove 1 . The stove 1 has feet 12 positioned widely spread at the extremities of the stove. This ensures better stability.

Figure 1 also shows the main chassis 2, heat shield 3, hand recess 4 and fasteners 5. The heat shield 3 protects the containers 7 from excessive heat while the hand recess 4 provides easy lifting of the stove. These features are not consequential to the present invention.

From the top portion of the stove 1 as shown in figure 1 it would be clear that the supports 19 are provided so that cookware (not shown) may rest upon these, positioned above the burners 18. Windshields 16 are provided surrounding the top portion of the burners 18. These windshields 16 minimize hindrance caused by wind on the flames, and are equipped with multiple flaps 17 that further redirect the wind away from the flames. Details of the burners 18 and how those work are shown and explained later with reference to figure 9.

From figure 1 it would be also clear that fuel-containing containers 7 are located in the lower portion of the stove body. These containers 7 can slide along inner guide rail 9 and outer guide rail 13 for loading and unloading purpose. These guide rails 9, 13 are provided at the bottom portion of the containers 7 as will be clear from figure 3 discussed later. Container 7 is equipped with flanges 23 (best shown in figure 8) which make it possible to glide on these rails. It is also envisaged that by extending the rails downwards these could alternatively allow the base of the container to glide upon the benchtop / table the stove 1 rests upon, eliminating the need for flange 23, but requiring the rails 9, 13 to be deeper.

It should be clear from figure 1 that the containers 7 may slide in and out from the side portion of the stove 1 which is facing the cook. To ensure that the containers 7 do not slide out of the stove along rails 9, 13 from a direction opposite to the cook, stoppers 3b are provided as specifically shown in figure 3, a little later. Of course, this side portion may be termed the front portion as well. For the sake of convenience, this is referred to as "side portion".

To ensure that the containers 7 do not come out during burning, these are locked underneath the burners 18 during burning with a locking facility 8 (best shown in figures 3, 5), which is operatively connected to the regulator 14. When the regulator 14 is moved from the closed position, the locking means 8 is actuated and it prevents the container 7 from coming out. The opposite occurs when the regulator 14 is brought to closed position. The stopper 8 now releases the container 7 so that it may slide out along rails 9, 13 if required. This function is explained later while describing the operation of the stove 1 .

Figure 1 also shows the container handle 1 1 for pulling out the container 7 along the rails 9, 13 when desired. It also shows the regulator ends 6 and the regulator slots 15.

Figure 2 is also a perspective view similar to figure 1 . The only difference is that one of the containers 7 has been removed from underneath the stove 1 . As explained before, this is possible only when the container 7 to be removed and its associated burner are extinguished. The top portion 7b of the container 7 has a lid 7a which is removably assembled at container lid seal 7d via a tight friction or interference fit. The container handle 1 1 can also be now clearly seen which is used to pull out the container 7, from underneath the stove 1 . The mesh 7c can also be seen. All these are explained further with reference to the exploded view of the container 7 in figure 6.

Figure 3 is a view of the bottom or underside portion of the stove 1 with the containers 7 removed and the burners 18 partly open. It clearly shows the inner guide rails 9 and the outer guide rails 13 along which the containers 7 (not shown in this figure) slide and also the spring 21 . It also shows the burners 18 and the burner pivots 18b. The container stopping facility 3b can also be seen here which ensures that the containers 7 do not slide out of the stove 2 in a lateral direction opposite to the cook or along a direction that is opposite to the regulators 14. Figure 3 also shows an important feature, namely the air ventilators 20 which are located along the underside of the body of the stove 1 . The positioning of these on the underside of stove 1 ensures that spillage of food during cooking does not affect the air ventilations 20 because the air ventilations 20 are located along the undersides of the stove 1 . This is an advantage over other existing stoves where such air vents are positioned up on the sides of the stove.

Figure 3 also shows slots 3a positioned in the underside of heat shield 3 through which the primary air 20 is supplied to the burners 18. Slots 3a are arranged radially around each burner 18.

Figure 4 is a cross sectional view of the stove 1 which shows its torsion box construction. This ensures that the stove 1 is both light weight and very strongly constructed, and is thus inexpensive and simple.

Figure 5 is a perspective view of the stove 1 with the main chassis 2 removed. It specifically shows the locking mechanism of the containers 7. It also shows the configuration of the burners 18. A more detailed description explaining the functioning of the locking mechanism shown in Figure 5 is provided a little later.

Figure 6 is an exploded view of the container 7. Each container applied in the stove 1 of the present invention includes a base 10 and a handle 1 1 for extracting container 7 from stove 1 . The container 7 is filled with a mineral wool 7e,7f,7g and wick material 22 (best shown in figure 8), where the mineral wool prevents both spillage of the fuel and fuel vapor formation, while the wick material ensures a steady supply of fuel delivered to the top surface of wick 22 by means of capillary action. Mesh 7c is positioned atop a mineral wool ring 7e and held in place by lid 7a. The disposition of the mineral wool ring 7e within the container 7 is also clear from figure 6. This figure also shows the outer mineral wool 7f which surrounds the outer portion of the mineral wool ring 7e, thereby completely filling the container base 10. The lid 7a can be opened to replace mesh 7c, wick material 22 and mineral wool 7e, 7f as these may become clogged after using for some time. The container lid 7a removably assembles to container top 7b via container lid seal 7d. The configuration of the seal 7d would be further clear from the cross-sectional view of the container 7, as shown in figure 8.

The configuration shown in figure 6 explains that the lid 7a can be removed from top to replace the wick, mineral wool and mesh once these become clogged after using for some time. This is an advantageous feature of the stove 1 . Figure 7 is a view of the top portion of the container 7 and figure 8 is a cross sectional view along the line A-A in figure 7.

Figure 9 is an enlarged view of an embodiment of the burner 18, which is also shown well in figure 5. It is comprised of four burner tubes 18a around a pivot 18b positioned centrally in plate 18e.The burner tubes have secondary air intakes 18c, which advantageously mix secondary air with the primary air drawn in from below through slots 3a in the heat shield. This is further explained later. Figure 9 also shows the burner feet 18d which attach to the heat shield 3. Figure 10 is a top view of the burner shown in figure 9 while figure 1 1 is a cross- sectional view of a burner along the line A-A in figure 10. Figure 12 is an enlarged view of the windshield shown in figure 1 .

All these figures 6 to 12 and the various features illustrated therein are elaborated on a little later, during an explanation of the function of the stove 1 .

Having described the basic structure of the stove 1 , the functioning is now explained and for that purpose, the figures 1 to 12 are again referred to.

Referring to figure 1 first the loading and unloading of containers 7 is explained. The containers 7 are located in the lower portion of the stove 1 , just beneath the burners 18. These containers 7 are the fuel containers. The fuel can be ethanol or methanol or mixtures thereof having say 90% concentration or similar fuel as may be known to persons skilled in the art. Referring to figure 2 for the purpose of refilling the container 7, the regulator 14 is set to the off/closed position thus releasing locking mechanism 8, and the container 7 is pulled out using the handles by sliding along the rails 9, 13. The configuration of these rails 9, 13 are best shown in figure 3, and these rails 9, 13 are arranged such that flange 23 of the container 7 may slide in a direction towards or away from the cook. Springs 21 ensure that the containers 7 locate firmly directly in position under the burner 18. Springs 21 also ensure that the containers do not in adverdantly slide out of the stove when the regulator 14 is set to the off position, by providing continuous upwards pressure on the containers 7.

It has been found that containers may eventually become clogged with soot or other byproducts of the burning process after some time. An advantage of the container embodiment described here is that it is possible to exchange the contents of container 7 if required, without damaging the container in the process. With the container 7 removed from stove 1 ,the lid 7a is opened from top portion and the mesh 7c, wick 22 (best shown in figure 8) and mineral wool 7e, 7f, 7g(best shown in figure 8) may be withdrawn and replaced. How, this is possible would be specifically clear from the exploded view in figure 6.

Referring to figures 1 and 3, insertion of a filled container into the stove involves, sliding the containers 7 along the rails 9, 13 from front to back, with the regulator 14 in the off position. To light the stove the regulator 14 is then moved to the fully on/open position, automatically locking the container 7 in place, and the burner 18 may be lit from above. All these operations are done from the side facing the cook, or in other words from the side having the regulators. It should be understood from the functioning explained in the preceding paragraphs, that the operation is very convenient and can be done very quickly without causing hindrance to the cooking process.

As may be obvious it is an important feature that the containers 7 are locked in position while the stove 1 is in use, as their removal while burning would prove a hazard to the user and surrounding environment. Thus, locking mechanism 8 is provided to ensure that they may not be removed prior to their being extinguished.

From figure 3 in particular, it would be clear that the stoppers 3b ensure that the containers 7 do not slide out of the stove along rails 9, 13 in a direction which is opposite to the cook, i.e. in a direction opposite to the regulators 14.

The containers 7 cannot be pulled out unless and until the regulator 4 is in an off position, as otherwise the containers 7 remain locked. This mechanism is now explained with reference to figure 5.

Figure 5 shows the position of the lock in open position 8a and also in closed position 8b. Locking detail 8 is rotatably attached to heat shield 2, such that it may rotate up and down, either allowing or hindering the container 7 to slide along rails 9, 13. Regulator 14 is constructed such that it is operably connected with locking detail 8, and the sideways rotation of regulator end 6 results in the rotation of locking detail 8 in a vertical plane. In this embodiment, regulator 14 is equipped with cam blades 14d which act upon locking means 8 and force it to rotate. Referring to the left hand portion of figure 5 when the regulator 14 is in off position, the lock is in open condition 8a. Now the container 7 may be drawn out of the stove 1 from its side facing the cook. Referring to the right hand portion of figure 5, the regulator 14 is now in on position and the lock is therefore actuated and it is now in a closed position 8b. At this stage, the container 7 cannot slide out along the rails. This is possible only, when, the regulator 14 is again brought to off position as shown at the left hand portion of this figure 5. Hence, the containers 7 remain locked when the stove is on and can be slid out only by extinguishing the relevant burner 18 by turning the regulator 14 to an off position.

The aspect defined in the preceding paragraph ensures safe cooking and quick as well as convenient refueling and maintenance of the stove 1 .

The exploded view in figure 6 explains that the top lid 7a of the container 7 can be removed for replacement of the mesh 7c, the wool 7e,7f,7g, and the wick 22. This has been elaborated upon before and is not repeated here. Now a very important aspect of the container is explained with reference to figures 7 and 8, figure 7 being a top view of a container 7 and figure 8 being a cross-sectional view along the line A-A in figure 7.

Referring specifically to figure 8, it shows that the container has a sloping base 24. Precisely, the container 7 has a low central bottom. This ensures that the fuel, say for example ethanol, flows to the middle of the container 7 and is hence drawn up more effectively through the wick material 22. This aspect, which ensures high burning efficiency, would be clear from the configuration of the sloping base 24 and that of the wick material 22, as shown in figure 8.

The cross-sectional figure 8 also shows the mineral wool ring 7e, the container lid seal 7d, the mesh 7c, wick 22, the mineral wool ring 7e, mineral wool center 7g and mineral wool outer 7f. Container flanges 23, for sliding along guide rails 9, 13 (best shown in figure 3) are also visible in figure 8.

Now another important feature of the stove 1 is explained with reference to the enlarged view of the burner 18 in figure 9. The burner 18 comprises say four burner tubes 18a encircling the burner pivot 18b attached to plate 18e. Each burner tube is provided with secondary air inlets 18c through which secondary air is drawn in when the flame is lit. The advantage of this is explained with reference to figure 1 1 which is a cross-sectional view of a burner 18 along the line A-A in figure 10, the latter being a top view of the burner 18.

Primary air is supplied from below the heat shield through slots 3a, and then referring to figure 1 1 , the primary air 20 comes in through the bottom portion of the burner 18 when the flame 25 is lit and this supplies oxygen to the flame 25. Due to presence of secondary air intakes 18c, second burning of the ethanol fumes (or other fumes as explained previously at the beginning of detailed description) takes place.

Mixing of primary air 20 from below the burner tubes and secondary air from the secondary holes 18c of the burner tubes 18a ensure excellent mixing of air during burning. Hence, the flame 25 is not only powerful, but also the flame is hotter, purer and generates less soot by virtue of more complete combustion. This also ensures that the emission level is reduced considerably. Regulation of the burners 18 is effected by regulators 14. Regulator 14 is positioned against the underside of burner plate 18e, and rotates around central pivot 18b. A series of openings in plate 18e (best shown in figure 9) coincide with similar openings 14a in regulator 14 and as regulator 14 is rotated against plate 18e the interaction and occlusion of both sets of openings controls the primary airflow through slots 3a and also the area of container wick 22 exposed to the burner tubes 18a. Regulator 14 is equipped with a series of flat areas 14b and raised areas 14c, which may expose or cover the air slots 3a in heat shield 3 as regulator 14 rotates. This ensures that primary air is drawn in from below the burner 18 so that the flame can be initiated and strengthened. In the same movement the regulator 14 also controls the area of the container mesh 7c and wick 22 exposed beneath each burner tube 18a, this ensuring the correct mix of fuel and oxygen. Thus regulator 14 which by interaction with the underside of burner plate 18e can control the flame by controlling the flow of primary air 20. It is worth mentioning that as explained before with reference to figure 5, turning on and off the regulator 14 also simultaneously locks and unlocks the containers 7.

Figure 12 is an enlarged view of the windshield 16 also shown in figure 1 . It is constructed in addition so as to have a series of flaps 17 and ensures that the wind flows sideways and does not blow on the flame directly. It is possible to take off the windshield 16 for transport and cleaning.

Figures 13 and 14 show two additional alternative embodiments of the burner 18.

The embodiment of the burner 18 shown in fig. 13A and 13B comprises a cylindrical burner tube 18a vertically arranged atop a largely circular baseplate containing a number of, preferably four, apertures 18f e.g. largely trapezoidal in shape. Even more preferably each of the apertures are largely wedge shaped such that they are comprised of four edges, two sides oriented largely radially towards the center of baseplate 18e and the two arranged concentrically in an inner and outer arc also concentric with baseplate 18e. In this embodiment the 4 apertures are evenly arrayed concentrically around the baseplate 18e with an even spacing between them. In this embodiment the outer arc of each aperture is coradial and equal with the internal diameter of burner tube 18a where a diameter of 48mm has been found to function admirably. An inner arc diameter of 17.5mm for each aperture combined with an included angle of 48 degrees between the 2 radially oriented long sides of the aperture has also been found to provide an excellent combination of turbulent air/fuel flow. These apertures in the bottom face both allow primary air 20 to enter and create turbulence and give an effective mixture of ethanol and air. Air entering these apertures is called primary air 20, since it is this air that enters the lowest part of the burner tube close to the ethanol container. The distance 26 between the underside of the burner baseplate 18e and the highest surface of the ethanol container lid 7a can for example be from 2 to 7 mm, depending on the dimensions of the burner and the diameter of the opening in the container. The combination of the carefully modulated supply of air 20 allowed through the aforementioned gap between the burner baseplate 18e and the container lid 7a, and the turbulence in this airflow created by the shaped apertures 18f in baseplate 18e creates an optimal blend of air and ethanol gas within the burner 18. This results in an improved (more complete) and thus cleaner combustion, and a flame that is both of a higher temperature and contains a greater percentage of blue colour than the flames achieved by existing commercially available ethanol stoves. An additional and visible benefit of this more complete combustion is a reduction in soot levels that occur on the underside of cookware positioned above the burner 18. The relationship between the size of the apertures 18f and the size of the central opening in the container lid 7a is also an important one in obtaining the optimal balance of output, fuel efficiency and minimal emissions / soot production. In the embodiment described in Figures 13A, 13B, 15, 16 and 17, it is preferred that the total area of the apertures 18f in baseplate 18e equals between 5 - 20% of the area of the central opening in container lid 7a, whereby baseplate 18e is of equal or greater diameter than the opening in lid 7a. To clarify, in such a relationship, only 5-20% of the container 7 opening is exposed when viewed through the burner 18 from above. Even more preferably the total combined area of the multiple apertures 18f lies in the range 8-15% of the area of the central opening in lid 7a, as an opening area in this range has been found to be very effective. It will be apparent that the relationship of areas described above is based upon the container 7 opening being fully exposed beneath the burner 18, and not partially or fully occluded by regulator disc 14e, as said relationship will change dynamically as the regulator occludes the container 7 opening. The burner 18 of this embodiment is also equipped with a plate 18g positioned over the upper mouth of the burner tube 18a. This plate, hereafter called a flame spreader, is formed such that it only partially occludes the opening of tube 18a, and forces the flames to spread out around said plate. This has the effect of decentralizing the flame where it meets the cookware placed above it, and allows for a more even heat transfer to the cookware, without a central hotspot. The flame spreader 18g has the additional benefit of introducing a secondary mixing/turbulence point whereby any uncombusted fuel vapor traveling upwards meets both the hot underside surface of the flame spreader and the flame simultaneously, ensuring a final turbulent mixing point contributing to complete combustion. The addition of such a flame spreader 18g may provide the additional benefit of discouraging unskilled users from adding fuel to the container 7 directly through burner 18, a potentially dangerous and undesirable method.

The embodiment shown in figures 14A and 14B has a gradual transition area between the burner tube and the flame spreader 18g. The oval (half ellipse) shaped apertures 18h give a continual high flame temperature due to protection against draft (from the side). The shape of these apertures 18h gives a more stable flame since the flames exit from the burner tube is less abrupt and more gradual and is less vulnerable to side draft. In addition the more protected flames are more evenly spread against the bottom of the cookware, contributing to a more effective heat transfer. The apertures 18h divide the main flame into three or more stable, separate flames with high temperature which subsequently are directed out to each their sectors over the bottom of the cookware and give little flickering and sooting. The number of apertures 18h may be different from three shown in fig. 14A and 14B, and their shape may also be altered without deviating from the intention of the design, although an alternate shape may not provide all of the intended benefits. These apertures 18h may also be referred to as flame outlets.

Figures 15 and 16 show an alternative embodiment of the heatshield 3 subassembly. In this embodiment, the heatshield 3 has been reduced in size such that a subassembly is formed for each burner 18. This has the advantageous effect of producing a scalable solution where this subassembly can be used together with a chassis 2 in varying configurations to provide a stove 1 with from one to for example three burners 18. In this embodiment the sides of heatshield 3 have been formed into vertical walls 3c folded downwards to surround the container 7 on the left and right sides. At the end of each wall are one or more mounting flanges 3d which allow springs 21 to be directly mounted to them with suitable fasteners, for example pop rivets. This allows the container flange 23 to slide directly on springs 21 thus negating the need for guide rails 9,13. It is possible to improve the sliding performance of the container on the springs and reduce the friction in the insertion and removal of the container by the addition of a layer of suitable plastic atop the springs. Such material may for example be a ultra high molecular weight polyethylene or PTFE (commonly referred to as Teflon) type material. The upwards pressure exerted by springs 21 on container flanges 23 results in container 7 being pressed up into the matching recess provided in heatshield 3. The highest point of the truncated cone central to container lid 7a will protrude through the opening in heatshield 3, resting such that the distance from the highest surface of lid 7a to the underside of burner plate 18e is from 2 to 7mm, even more preferably about 4mm. Extensive testing has shown that this allows a suitable amount of primary air 20 to flow into this gap, and flowing onwards through apertures 18f providing an excellent fuel to air ratio for clean and efficient combustion. Due to heatshield 3 being narrower in this embodiment, airflow is provided at the left and rights sides such that primary air 20 is drawn both from these sides in addition to through slots 3a positioned radially around burner 18. Such an airflow provides the additional advantage of cooling the container 7 as it flows around and over. In this embodiment, regulator 14 rotates around a pivot point 3f on the heatshield, thus rotating in or out under burner plate 18e to regulate both the fuel supply and air supply 20 and thus the resulting flame 25. The regulator disc 14e is formed with multiple radial ridges that both strengthen the part, and result in a seal when disc 14e is in the closed position centered over the opening in container lid 7a, preventing evaporation of remaining fuel in container 7. This embodiment provides both the economic advantages of a reduction in the number of components required and provides a scalable platform for production of further stoves with a greater or lesser number of burners.

Figure 17 shows yet another embodiment of burner 18, with the parts exploded in order to better present the features described below. In this embodiment, the apertures 18f in baseplate 18e are equipped with an angled flap 18i along one edge. The angled flaps 18i have the beneficial effect of introducing an additional direction vector to the incoming fuel/air mix and resultant flame. In this embodiement all of the apertures 18f are equipped with the flap 18i along a corresponding largely radially oriented edge, such that a spiral air flow is introduced. This has several benefits, the first being the introduction of additional turbulence into the upwards airflow in a manner that is sympathetic to the flow direction and does not introduce great resistance to the flame path. This additional turbulence results in even better mixing of the fuel and air such that combustion is more complete. The second benefit is a more cohesive centrally oriented flame, where, due to the spiral air flow, the flame is less susceptible to sideways interference due to wind or drafts etc, which would otherwise cause the flame to gutter and become unstable. The third benefit is that less of the energy from the flame is used to heat the vertical tube as the spiral flame is better centralized. It is also possible to affect the degree of spiral flow that is introduced by for example combining the angled flap 18i with one or more of the apertures 18f, with maximum spiral flow achieved by equipping all of the apertures with flaps 18i. The description of the flaps 18i above should not be viewed as exhaustive - it should be apparent that the flaps 18i may be arranged differently without departing from the spirit of the invention. More specifically, the flaps 18h may be arranged at a different edge of the aperture to achieve a reverse spiral, centralized airflow or other turbulent effect. The flaps 18i may also be arranged across more than one edge for example spanning two neighbouring edges. It is also possible to equip each aperture with more than one flap detail 18i, ie along multiple edges, or by equipping a single edge with two smaller flaps. The flap 18i may also be formed as a tooth-like detail that enters the aperture from one or more edges to enhance turbulent mixing.

When a regulator 14 is used to regulate the size of the opening in container lid 7a, it will be apparent that it will partially or fully cover the apertures 18f in burner baseplate 18e. Testing has shown that it can be beneficial to arrange the apertures 18f so that they are occluded in sequence as the regulator 14 is moved from fully open (full air/fuel flow) to fully closed (fuel closed and flame extinguished). It can further be advantageous to vary the size of one or more of the apertures 18f. In another embodiment of the burner 18, one of the apertures 18f differs in size and/or shape from the others, being preferably larger than the other apertures 18f. This larger aperture is then subdivided with one or more bridging elements. In this embodiment, the enlarged aperture 18f is positioned such that it is the last aperture unoccluded when the regulator covers most of the opening in container lid 7a and the flame 25 is set to a low setting. By enlarging the size of this final aperture 18f, it is possible to include one or more bridges to create turbulence in the fuel/air flow and ensure proper mixing and thus more complete combustion. Without enlarging this final aperture 18f, the introduction of the bridging elements would restrict the air/fuel/flame flow and thus be instead detrimental to the function of the burner in a low power setting. It will be obvious to a person skilled in the art that the bridges subdividing may differ in shape from those described above without deviating from the spirit of the design. More specifically, the bridging elements may range from a single element subdividing the enlarged aperture into two, to two or more elements parallel to or intersecting one another to subdivide the enlarged aperture into three or more sections. An alternate construction would be to use tooth-like details emerging from one or more sides to largely subdivide the enlarged aperture.

When cooking with the stove, it is apparent that it may be advantageous to adjust the size of the opening in container lid 7a, thus adjusting the area of fuel soaked wick material that is available as an energy source. The regulator 14 provides an admirable means of adjusting the amount of fuel that is provided to the burner 18, however another means of providing this adjustment is to provide an alternate lid 7a with a smaller central opening, that thus restricts the energy that may be provided by the fuel containing container 7. In this scenario, the user may be provided with 2 versions of lid 7a, whereby one has the original sized opening and is ideal for high power cooking needs (for example boiling water as quickly as possible) and the second alternate lid 7a version has a smaller opening that is ideal for a lower power setting (for example simmering of water / foodstuff / use with smaller pots.) In such a scenario, the user could first use a lid 7a with the largest opening to boil water, and then remove the container 7, exchange the lid 7a for that with the smaller opening and reduce the power output to a simmer level. An alternate solution in a stove 1 with two burners 18 might be to use one container 7 and burner 18 combination with a large lid 7a opening for high power cooking, and the second burner 18 combined with a container 7 with a smaller lid 7a opening, such that the user first boils the water/food on the high power burner/container side, before moving the pot/saucepan etc to the burner/container side with the smaller lid 7a opening arranged for a simmer/low power setting. During evaluation of various opening sizes in lid 7a, it has been found that a lid opening diameter of between 75-90mm is ideal for a high power setting, even more preferably a diameter of 86mm has been found to provide excellent results. In an alternate version where the opening is made smaller to suit a simmer setting, an opening with between 40-70% of the high power opening has been found to provide a suitable balance of efficiency and reduced power output. At the smallest opening sizes eg 40% of the circular area of the original opening, both efficiency and power output are acceptable, however the production of soot increases, so that the combined effected is not optimal. Thus even more preferably an opening of 66-70mm has been found to provide an excellent balance between efficiency, power and clean burning. It should be apparent that the use of an alternate lid 7a may be combined with the use of regulator 14 to allow maximal flexibility in the stoves usage.

In yet another embodiment of the stove 1 , an alternate solution is provided to control the amount of fuel exposed under the burner 18 and the shape of the opening exposed. In this embodiment, a ring shaped component hereafter called a simmer ring, is used to alter the opening size of container 7, allowing the user to both take advantage of the containers full energy potential with the opening in lid 7a fully open, and to employ the simmer ring to uniformly reduce the opening size for an energy efficient low power setting. Said simmer ring may either be in it^'s simplest form a loose ring that may be manually placed into the container 7a opening prior to insertion into the stove or it may be an integrated component of the stove. In the latter case, the simmer ring may be attached/integrated with an arm whereby its use may be combined with that of regulator 14. In this case the simmer ring and arm may share the pivot point 3f on the heatshield, whereby the arm protrudes out through the same slot as regulator 14, such that the user may adjust both from the front of the stove 1 . In this way the user can perform a simple simmer setting adjustment by rotating the simmer ring and arm so that the ring sits concentrically with the opening of container lid 7a. Regulator 14 may then be rotated across to perform finer adjustments of the stoves power output.

In a further embodiment of the stove, regulator 14 is divided into 2 elements that are connected such that they occlude the opening in heatshield 3 / container lid 7a from 2 sides simultaneously, ie an adjustment of the regulator arm 14 controls a linked and corresponding movement from a second regulator component. The shape of the regulator discs 14e may be formed in a variety of shapes designed to seal the opening and either meet or overlap each other in the closed or off position. These may for example be provided as two half discs that meet along their flat side when closed over the container opening, or two crescent shapes that overlap to occlude the container 7 opening, or alternatively two squares that meet or overlap along one edge when closed. In this and any of the described stove embodiments, it is also envisaged that the manual movement of regulator arm 14 from side to side may alternatively be achieved by the use of knob which translates a rotational movement into a transverse movement to achieve the necessary movement of regulator 14.

The open construction of the stove 1 like a bridge ensures that maximum airflow and cooling of the containers 7 and also ensures loading and unloading the containers 7 easily and conveniently from the side facing the cook.

From the description hereinbefore it would be clear that all the objects of the invention are achieved. The present invention has been described with reference to a preferred embodiment and some drawings for the sake of understanding only and it should be clear to persons skilled in the art that the present invention includes all legitimate modifications within the ambit of what has been described hereinbefore and claimed in the appended claims.

Claims

Patent claims

1.

Stove (1) for burning liquid alcohol, preferably ethanol, methanol or a mixture of these, comprising one or more burners (18) for generating flames from fuel supplied from container(s) (7), said stove (1) having support(s) (19) for supporting cookware above the burner(s) (18)

characterised in that the burner(s) (18) are comprised of a largely vertically arranged burner tube (18a) atop a baseplate (18e), said baseplate (18e) equipped with two or more apertures (18f) and arranged above fuel container (7) with a vertical separation distance of 2-7mm.

2.

The stove according to claim ^characterised in that the combined area of the apertures (18f) in the baseplate (18e) comprises 5-20% of the area of the central opening in container (7)

3.

The stove according to claim 1 or 2, characterised in that the burner tube (18a) has an integrated flame spreader (18g) and two or more flame outlets (18h) at its upper part.

4.

The stove according to any of the preceding claims characterised in that the apertures (18f) are equipped with flap details (18i) along one or more edges.

5.

The stove according to claim ^characterised in that the burners (18) have burner tubes (18a) provided with secondary air intakes (18c) for a second burning of the fuel and primary air is supplied through the bottom portion of the burner tubes (18a).

6.

The stove according to any of the preceding claims, characterised in that the flow of primary air through the burner tubes (18a) can be regulated depending upon the flame required.

7.

The stove according to any of the preceding claims, characterised in that the fuel container (7) houses a mineral wool component.

8.

The stove according to any of the preceding claims, characterised in that the fuel containing containers (7) are slidably loadable and removable to and from the stove (1 ) along its front/side/rear portion.

9.

The stove according to claim 8, characterised in that the containers (7) are equipped with flanges (23) which glide on rails (9, 13).

10.

The stove according to claim 9, characterised in that the rails (9,13) can be extended downwards for allowing the base of the containers (7) to glide.

11.

The stove according to any of the claims 7 to 10, characterised in that the containers (7) can be replaced and loaded with the stove (1) still operative.

12.

The stove according to any of the claims 7-11 , c h a r a c t e r i s e d in that each container (7) is provided with a removable lid (7a) at its top portion to allow replacement of its contents.

13.

The stove according to any of the claims 7-12, characterised in that container (7) may be equipped with alternate removable lids (7a) each lid having a central opening of a differing diameter thus altering the energy output of the container.

14.

The stove according to claim 12, characterised in that the containers (7) remain firmly locked in the lower portion of the stove(1 ) during burning by means of a locking means (8), which is actuated once the regulator (14) of the stove is put on for burning and unlocks automatically once the regulator (14) is put off to stop the burner (18) .

15.

The stove according to any of the preceding claims, characterised in that each container (7) has a low central bottom with sloping base (24) for enabling the flow of fuel towards the middle portion of the container (7), such that the fuel is effectively drawn through the wick material.

16.

The stove according to claim 1 , characterised in that each burner (18) is equipped with multiple burner tubes (18a).

17.

The stove according to any of the preceding claims, characterised in that its body is of a torsion box construction type for making it light and inexpensive, air apertures (20) are provided along the underside of the body of the stove (1 ) for protection against spillage of food there, and the stove(1) has an open, bridge-like construction.

18.

The stove according to any of the preceding claims, characterised in that the stove is constructed from a chassis (2) housing one or more subassemblies comprising one burner (18), one heatshield (3), one regulator assembly (14) and one fuel container (7).