WO2008058566A1

WO2008058566A1 - Stove

Info

Publication number: WO2008058566A1
Application number: PCT/EP2006/011070
Authority: WO
Inventors: Bengt Ebbeson; Hans-Olof Andersson
Original assignee: Dometic Ab
Priority date: 2006-11-17
Filing date: 2006-11-17
Publication date: 2008-05-22
Also published as: CN101677717B; BRPI0622126A2; CN101677717A

Abstract

The present invention relates to a stove comprising at least one burner for generating a flame from a fuel, the stove having a cookware holder for supporting cookware at a distance over the burner. The stove according to the invention is characterized in that the distance between the burner and the cookware is large enough such that the mean carbon monoxide content in the emission is 30-60 ppm, preferably 40-50 ppm, with an efficiency factor of the stove of about 40-65%. In this manner, noticeably improved emission values are obtained such that the range of application of the stove according to the invention is broadened. The burner of the stove is preferably a burner for the depressurized generation of flames.

Description

The present invention relates to a cooker with at least one burner for producing a flame from a fuel having a cookware holder for holding a cookware at a distance above the burner.

Such cookers are widely used in the camping area, in recreational craft or in developing countries. Usually, these cookers are designed to be as compact as possible in order to make the most efficient use of the usually already small amount of space in camping vehicles or boats. The same applies to the cookers which are widespread in developing countries, since these also often have to be operated in very small and confined spaces. However, due to the exhaust gases generated by the digesters, there is basically a certain limit up to which they should be operated in small, poorly ventilated rooms.

The invention is based on the object of specifying a digester which has an enlarged range of application.

This object is achieved with the digester according to claim 1. Advantageous developments are described in the subclaims. The cooker according to the invention differs from the generic cookers described above in that the distance between burner and cookware is so large that at an efficiency of the digester of about 40-65% of the average carbon monoxide content in the exhaust gas at 30-60 ppm, preferably at 40-50 ppm. As a result, overall noticeably improved exhaust gas values are obtained, as the inventors have ascertained in numerous investigations, so that the scope of application of the digester according to the invention is increased. This approach is based on the finding that it is sufficient to adjust the distance between burner and cookware from the almost infinite number of influencing parameters for the exhaust gas values of a digester only with regard to the two parameters efficiency and carbon monoxide content.

Accordingly, the cooker according to the invention has an overall significantly lower emission exhaust gas than the known cooker. In particular, not only the carbon monoxide content is reduced, but also the carbon dioxide contents, nitrogen oxides and particulate matter are reduced. At the same time, this parameter combination represents an optimum compromise between the highest possible degree of efficiency and the lowest possible carbon monoxide content at the expense of a generally increased overall height. The inventive cooker is higher than the cookers currently in use. In this respect, the present approach is also extremely baffling, since the scope of the known cooker is improved by the fact that the height is increased. With this measure, but it succeeds to create a stove that can be used not only outdoors or in large rooms, but especially in very small spaces, because it has more favorable emissions. So despite its increased height, it is particularly well suited for use in boats and camping vehicles.

The burner of the cooker is preferably a burner for pressureless flame generation. These have the advantage that they are particularly simple and are relatively easy to use. It is particularly advantageous if this is an alcohol burner, in particular a spirit burner. Alcohol or spirit distillers have the advantage over the widespread petroleum or kerosene burners that alcohol is much easier to extinguish in case of fire. For example, petroleum is an oily substance that can only be extinguished badly with water, while Alcohol can be diluted with water and can therefore be quenched with water. Preferably, the burner is a liquid fuel burner because liquid alcohol is widely used and therefore easy to obtain. It is also possible to use fuels bound in gel, such as an alcohol gel.

Preferably, the burner has a burner tube. This stabilizes the flame, which is relatively unstable, especially in the case of pressureless flame generation, by means of a vertical gas flow which is established in the burner tube.

In another development, the cooker on a housing with a hob on its top. In this housing, the burner is arranged so that it opens, in particular with its combustion pipe, in the hob. This protects the burner from overcooking contents from the cookware. Also, the hob is easy to clean, as it is preferably carried out largely flat.

Advantageously, the distance between the burner and cookware is 30 mm to 80 mm. At such a distance, it is possible to reliably maintain the efficiency of the digester sufficiently high and at the same time to reduce the carbon monoxide content. However, it should be noted that the distance between burner and cookware may well have other values, this ultimately depends on the performance of the burner. The distance values given above refer to a burner with a capacity of around 1.7 kW.

Further, the cooker has a windshield mounted on the hob to protect the flame from lateral wind. This windshield has at its lower area facing the burner, a fresh air supply and at its the cookware facing upper area on an exhaust outlet. Between the supply of fresh air and the exhaust gas outlet, the side wall of the draft shield is as high as possible in order to create a pronounced chimney effect in the area of the flame. However, the height of the side wall is limited by the efficiency to be achieved. The chimney effect not only protects the flame from lateral wind, but also from the chimney effect between burners with burner tube and burnerless burners. stabilized fresh air supply and exhaust outlet. This stabilization is of great importance especially for pressure-free burners. At the same time, the oxygen supply of the flame improves in such a way that not only the efficiency of the digester increases, but also that lower carbon monoxide contents in the exhaust gas occur.

Particularly useful, the windbreak therefore has a closed-walled annular plate as a side wall. This results in a particularly powerful chimney effect, ie a particularly strong vertical flow from bottom to top in the area of the flame.

Conveniently, the windshield spacers, with which its side wall is maintained at a defined distance from the housing top, wherein the gap thus formed between the side wall and housing top side forms the fresh air supply. Such a windbreak can be easily and well produced and is also extremely robust. To be particularly favorable, it has been shown that the side wall of the windbreak has a height which is about five to six times as large as the distance between the side wall and the top of the housing.

Windscreen and cookware holder are preferably a common component. This reduces the number of parts on the stove, so that it is not only inexpensive to produce, but also easy and easy to clean.

The spacers of the windbreak can be designed so long that a cookware can be stored on their upper end faces. It is particularly expedient if the spacers of the windshield are carried out so long that they project beyond the side wall, wherein the gap thus formed between the bottom of the cookware and the side wall forms the exhaust gas outlet.

In this case, spacers have been shown to be suitable, which are designed as planar support plates, which are aligned and fixed pointing radially inward on the annular side wall. These can be fastened to the side wall via attachment flanges or else be attached to the side wall in a blunt manner. Suitable fastening methods or are welding, riveting or screwing. It is particularly advantageous if at least one spacer has on its underside a fastening possibility, in particular a recess, with which it can be fastened to the boiler housing, in particular in a holder. As a result, the draft shield or the cookware holder is very well fixed relative to the cooker housing. This noticeably reduces the risk of accidents. The advantage of a latching connection is that the housing and the draft shield or cookware holder can be easily connected to each other or detached from each other. This facilitates the cleaning and maintenance of the stove.

In an expedient development, the spacer has in each case at least one notch or opening close to the floor, which enables flows in the interior of the windscreen which are close to the side walls and directed in the circumferential direction. Thus, a rotating around the flame center flow in the gas or exhaust gas can adjust within the windshield. Measurements have shown that this can further reduce the carbon monoxide content and improve the efficiency of the digester according to the invention, so that in return a slightly smaller increased distance between the underside of the cookware and the burner can be used to comply with the limit values mentioned above.

Another advantage of the spacers described above is that you can easily change them. So you can easily vary the number or give the sheets different shapes. For example, it is sometimes useful to let the spacers protrude further into the center of the windscreen, for example to be able to set up very narrow pots. Des can be done for example easily by bolted cantilevers. It is also desirable for certain applications to place on the front sides of the spacers grids or grids that span the stove and in particular the hob. So pots of different sizes can be set up and, if necessary, placed aside next to the flame.

Conveniently, the spacers may have a width that is substantially constant over their height. So they have a relatively easy to manufacture form. However, it has been shown that the efficiency of the digester according to the invention then again increases when the spacer has a decreasing from the burner side to the cookware side width. This effect is further increased when the exhaust outlet is larger than the fresh air supply. Thus, measurements with a 35 mm high ring plate and a lower distance to the housing top of 8 mm and a top distance to the cookware of 16 mm yielded an efficiency of 61.3% compared to 58.7% for a symmetrically arranged between cookware and hob windshield. Due to this downwardly shifted arrangement of the windguard, however, the protection of the flame from horizontal wind is somewhat less pronounced. However, this is acceptable for stoves that are operated substantially indoors.

The housing of the digester expediently has a second fresh air supply for the burner. As a result, the combustion is even more efficient because the burner can suck additional fresh air through the housing. It is particularly good if the second fresh air supply is arranged below the burner, since then sets a vertical air flow in the region of the burner and there within the flame. This stabilizes the flame and makes combustion more efficient.

The invention will be explained in more detail with reference to embodiments illustrated in the drawings. In it show schematically:

Fig. 1 is a perspective view of a first embodiment of the stove according to the invention;

2 shows a section through an upper part of a second embodiment of the stove according to the invention.

Fig. 3 is a plan view of the windshield ring shown in Fig. 2;

4 is a perspective view of the top of a third embodiment of a windshield ring;

Fig. 5 is a perspective view of the underside of a fourth embodiment of a windshield.

The cooker 1 shown in Fig. 1 is a spirit stove with a housing 2 made of a stainless stainless steel. In the housing 2 are two spirit burners 3 arranged, the burner tubes 4 protrude through the top 5 of the housing 2. The housing top 5 thus forms a hob with two burners. In this case, the hob 5 covers the burner 3 as far as possible, so that in Fig. 1 actually only the burner tubes 4 of the two burners 3 can be seen, as they protrude through the hob 5 through the top.

In the region of each of the two burners 3 is located on the hob 5, a cookware holder 6 and a windshield 7. In the embodiment shown in Fig. 1, the cookware holder 6 is connected to the windshield 7 to a common component. The side wall 8 of the windshield 7 is welded to the respective three spacers 9 in the annular wall sheet designed as a closed wall. The spacers are in this case narrow, elongated and vertically aligned sheets that stand up with their lower end faces 10 on the hob 5 and their upper end faces 11 serve for Auflagerung a cookware 12, as shown in Fig. 2 for a second embodiment.

In the embodiment of the draft shield and cookware holder shown in Fig. 1, the individual spacers 9 are aligned with a survey 13 in the hob 5. This elevation 13 extends annularly around the opening in the hob 5 through which the burner 3 projects with its burner tube 4. The spacers 9 are now slightly bevelled at its lower inner end and can thus come to rest on the side wall of the survey 13. The fact that the three spacers are evenly distributed over the circumference of the annular elevation 13, the windshield and cookware holder is centered to the burner tube 4 of the burner 3 and is secured against lateral slipping. At the elevation 13 and a flame distributor 14 is attached, which covers the burner tube 4 in a relatively small distance. The flame distributor 14 serves to improve the distribution of a flame, especially at low set power of the burner 3. The power of the burner 3 can be adjusted in each case via lever 15 on the side of the housing 2. Also, the levers 15 serve to extinguish the flame of the respective burner 3. Below the levers 15 are located below each burner flame three recesses which together form the second fresh air inlet 26 of the respective burner 3. The respective windbreak 7 has the highest possible side wall 8 which, together with a fresh air supply 16 defined by the windbreak 7 and an exhaust gas outlet 17, effects a pronounced chimney effect in the region of the flame generated by the burner 3. Under pronounced chimney effect is here to understand a strong and stabilized by the side wall 8 vertical flow from bottom to top. The fresh air supply 16 is thereby formed by the side wall 8 of the windshield 7 is held by the spacers 9 in a defined lower distance 18 to the housing top 5. Conversely, the spacers 9 of the windshield 7 are designed so long that a aufgestragende on the upper end faces 11 of the spacers 9 cookware 12 is held at a distance 19 to the side wall 8 of the windbreak 7. This distance 19 thus forms the exhaust gas outlet 17. The side wall 8 has in each of the two embodiments shown in FIGS. 1 and 2 a height of 38 mm designated by the reference numeral 28. The fresh air supply 16 has a height of 11 mm and the exhaust gas outlet 17 also has a height of 11 mm. Thus, the distance between cookware 12 and the housing top is 60 mm, while the burner tube 4 projects 22 mm above the top of the housing.

The two embodiments of FIGS. 1 and 2 differ substantially in the design of the lower end faces 10 of the spacers 9. While the spacers 9 shown in Fig. 1 have a substantially flat bottom, the spacers 9 shown in Fig. 2 each have a mounting recess 20 which is formed so that the spacers 9 on the cooker housing 2 and there in particular on the hob 5 can be engaged. In contrast to the first exemplary embodiment shown in FIG. 1, in this variant, the spacers 9 are wider, project closer to the burner 3 and also protrude with their front side on the elevation 13 of the hob 15. For this purpose, the recess 20 has an elongated trough whose shape corresponds to the top of the hob 5 and thus the elevation 13 follows. The recess 20 ends just before the inside of the spacer 9, so that a locking lug 21 is formed. This locking lug 21 is engaged in a correspondingly shaped receptacle 22 in the elevation region 13 of the hob 5 to securely attach the windshield and cookware holder.

Also, the spacers 9 of the embodiment shown in Fig. 2 are, as can be seen from the plan view shown in Fig. 3, uniformly over the circumference of the side wall 8 distributed and aligned radially inwardly to the center of the circular line on which the side wall 8 of the windshield 7 is located.

The burner 3 used in the exemplary embodiments of FIGS. 1 and 2 has a power of about 1.7 kW when burning a fuel mixture with 85% ethanol, 10% methanol and about 5% water at full power. If one now measures the time with which a cookware pot mounted on the cookware holder 6 and filled with 4 liters of water is heated from ^15.degree. C. to 95.degree. C., it turns out that the cooker 1 according to the invention heats the water significantly faster with around 24 minutes a conventional cooker with low wind protection, which at the same time only heats the water to 85 ° C. From the increase in temperature in the water can be determined taking into account the fuel consumed and its calorific value, the efficiency of the digester. This shows that even if the windshield 7 is designed to improve the oxygen supply of the flame from a perforated annular plate or is omitted entirely, the exhaust emissions of conventional cookers are worse than in the invention. This means that by increasing the distance 27 shown in FIG. 2 between the burner 3 and the cooking pot 12, taking into account the efficiency and the CO content, optimum combustion properties can be achieved. By taking these two parameters into consideration, an optimal compromise is achieved between the highest possible efficiency and the lowest possible Co content. Because at a very large distance, the Co content in the exhaust gas drops to zero while the efficiency is very low, since the heat losses of the flame are too large. Conversely, the CO content increases with a small distance between the burner 3 and saucepan 12 with increased efficiency. In the combination according to the invention, the CO content in the exhaust gas is now safe for users even in very small spaces and for a long service life of the digester, and the efficiency is still better than with cookers of conventional design. This is because with close approach of the cooking pot 12 to the burner 3, the efficiency also decreases again. In the present case, for the cooker 1 shown in FIG. 2, the CO content was measured with a maximum of about 70 ppm in the exhaust gas and an efficiency of 58.7% was determined.

In the third embodiment of a windshield or cookware holder according to the invention shown in FIG. 4, as in the second embodiment, Recesses 20 and locking lugs 21 for attachment of the windshield on the hob 5 are provided. However, this embodiment differs from that according to FIG. 2 in that the spacers 9 have a decreasing width in the direction of the cookware 12. For this purpose, the spacers 9 are cut inside. By this intersection of the spacers 9 increases the area below the cookware, in which the flame can unfold undisturbed by internals and at the same time allow the reduced widths of the spacer 9 and an enlarged, aligned in the circumferential direction, ie parallel to the windshield side wall 8, flow within the Flame or gases above the burner. This improves the oxygen supply to the flame so that the CO content is reduced to about 53 ppm compared to the first and second embodiments and the efficiency of the digester is increased to about 60%.

Furthermore, the spacers 9 shown in FIGS. 4 and 5 are fastened on their side facing the side wall 8 in each case via angled strips 23 by means of three spot welds 24. Also, the spacers 9 have a towards the cookware 12 towards decreasing width. However, in the fourth embodiment shown in FIG. 5, the lower end faces 10 of the spacers are designed differently again. Here, the lower end faces 10 of the spacers 9 have a larger notch 25. On the burner side leg of the V-shaped recess 25, in turn, a Rastaus- recess 20 is arranged, which, as already in the previous exemplary embodiments, defines a locking lug 21. However, the V-shaped notches 25 are now chosen so large that when mounted windshield 7, the notch-shaped recesses 25 do not completely come to rest on the housing, but define openings that allow a directed flow in the circumferential direction. In other words, that means that the lower end faces 10 of the spacers 9 are designed such that they can be flowed through in their end region. This again increases the efficiency and also reduces the CO content in the exhaust gas.

Claims

claims

1. A cooker (1) having at least one burner (3) for generating a flame from a fuel of a cookware holder (6) for holding a cookware (12) at a distance above the burner, characterized in that the distance between burner ( 3) and cookware (12) is so large that at one

Efficiency of the digester (1) of about 40% to 65% of the average carbon monoxide content in the exhaust gas at 20 ppm to 100 ppm, preferably 35 ppm to 75 ppm.

2. cooker according to claim 1, characterized in that the burner (3) is a burner for pressureless flame generation.

3. cooker according to claim 1 or 2, characterized in that the burner (3) is an alcohol burner, in particular a spirit burner, is.

4. cooker according to one of the preceding claims, characterized in that the burner (3) is a liquid fuel burner.

5. cooker according to one of the preceding claims, characterized in that the burner (3) has a burner tube (4).

6. Cooker according to one of the preceding claims, characterized in that the cooker (1) has a housing (2) with a hob (5) on its upper side, in which the burner (3) is arranged, wherein the burner (3) in the hob (5) empties.

7. cooker according to one of the preceding claims, characterized in that the distance between the burner (3) and cookware (12) is 30 mm to 80 mm.

8. cooker according to one of the preceding claims, characterized in that the cooker (1) arranged on the hob (5) windshield (7) to protect the flame from side wind, the windshield at its the burner (3) facing lower area a fresh air supply (16) and at its the cookware (12) facing the upper region has an exhaust outlet (17) and between fresh air supply (16) and exhaust outlet (17) as high a side wall (8) has a pronounced chimney effect in the area to create the flame.

9. cooker according to one of the preceding claims, characterized in that the windbreak (7) has a closed-walled annular plate as a side wall (8).

10. cooker according to one of the preceding claims, characterized in that the windshield (7) spacers (9), with which its side wall (8) is held at a defined distance (18) to the housing top, wherein the gap thus formed between the side wall and housing upper side forms the fresh air supply (16).

11. cooker according to one of the preceding claims, characterized in that the windbreak (7) and the cookware holder (6) are a common component.

12. cooker according to one of the preceding claims, characterized in that the spacers (9) of the windshield (7) are designed so long that a cookware (12) on its upper end faces (11) can be stored.

13. Cooker according to one of the preceding claims, characterized in that the spacers (9) of the windshield (7) are designed so long that they project beyond the side wall (8), wherein the gap thus formed between the underside of the cookware (12). and the side wall (8) forms the exhaust gas outlet (17).

14. cooker according to one of the preceding claims, characterized in that the spacers (9) are formed as a flat support plates, which are aligned and fixed on the annular side wall (8) facing radially inward.

15. A cooker according to one of the preceding claims, characterized in that at least one spacer (9) on its underside (10) has a fastening possibility, in particular a recess (20) with which it is attached to the cooker housing (2), in particular in a holder (22) can be engaged.

16. Cooker according to one of the preceding claims, characterized in that the spacers (9) each have at least one near-bottom notch (25) or opening, which allow a side wall near and directed in the circumferential direction of flow inside the windshield (7).

17. Cooker according to one of the preceding claims, characterized in that the spacers (9) have a height which is substantially constant over their height.

A cooker according to any one of the preceding claims 1 to 16, characterized in that the spacers (9) have a width decreasing from the burner side towards the cookware side.

19. Cooker according to one of the preceding claims, characterized in that the exhaust gas outlet (17) is greater than the fresh air supply (16).

20. Cooker according to one of the preceding claims, characterized in that the side wall (8) of the windshield (7) has a height which is about 5 to 6 times as large as the distance (18) between the side wall (8). and the top of the housing (2).

21. Cooker according to one of the preceding claims, characterized in that in the housing (2) at least a second fresh air supply (26) for the burner (3) is arranged.

22. A cooker according to claim 21, characterized in that the second fresh air supply (26) below the burner (3) is arranged.