WO1981001323A1

WO1981001323A1 - Heating stove

Info

Publication number: WO1981001323A1
Application number: PCT/SE1980/000268
Authority: WO
Inventors: S Nilsson
Original assignee: Merus Milieu Ab; S Nilsson
Priority date: 1979-11-02
Filing date: 1980-10-31
Publication date: 1981-05-14
Also published as: NO803269L; SE7909095L; EP0039705A1; FI803404L; DK463380A; GB2086562A; DE3049994A1; FR2468841A1

Abstract

Heating stove (1) of the type which is disposed in order to heat indoor air which is made to circulate through the stove in special channels (37, 39) and thereby cool down surfaces heated up by a fire and the flue gases produced. For the purpose of achieving a greater degree of efficiency, virtual eliminating emissions of toxic gases, eliminating the risk of cracks forming in the stove as well as avoiding any use of insulation material in the stove, the stove comprises a combustion chamber (11), in which at least one wall or preferably all the walls (12, 12", 13, 13") present exhibit a corrugated surface (44, 44"). The lateral walls (12", 13") can hereby be comprised of a liner disposed in the combustion chamber. Moreover, the stove comprises a flame spreader (20), which is disposed at a distance below the stove duct (19) and closely connected to the lateral walls of the combustion chamber, but leaving an opening (53) between a front edge (26) on the flame spreader and the closing-off doors (9) of the stove or the like. The flame spreader divides the combustion chamber (11) into a lower chamber (51) designed to comprise the hearth (56) itself and an upper chamber (52).

Description

Title: Heating stove

Technical field: The present invention relates to a heating stove of the kind which is disposed in order to heat air which is made to cir- culate through the stove, whereby the stove comprises a cas¬ ing and a combustion chamber, disposed in the casing and able to be closed by means of doors or the like, which combustion chamber being limited by at least lateral walls disposed in the casing and a rear wall, which may be present. Further the heating stove comprises a flue disposed for the removal of flue gases, a flame spreader, which displays a front edge fac¬ ing the doors or the like, and is disposed in the upper sec- tion of the combustion chamber, some distance below the flue, as well as a fan which is disposed to be able to increase the flow of air through the stove.

Background: Despite the existence of a number of different heating stoves and recent proposals for heating stoves and of a questioning nature, there is a need for a heating stove, which besides displaying a high degree of efficiency, both eliminates the risk of cracks forming in the stove, and primarily thereby in the vicinity of the combustion chamber as well as reduces or . virtually eliminates emissions of toxic gases, solid parti¬ cles or similar with the flue gases. Furthermore, there is a need to be able to avoid insulating material in these heat¬ ing stoves and particularly those possessing a fan-driven hot air system.

Technical problem:

In the case of known heating stoves it has proved necessary to use insulation material to prevent the exterior of the heat- ing stove from attaining an excessively high temperature. In installing the insulation material, the installing personnel have suffered from skin rashes and itching due to the insula¬ tion material. It has further been shown that when the fan- driven hot air circulation is in use, fibres from the insula¬ tion material are spread out in those rooms which are to be heated up by the stove. The flue is disposed above the com¬ bustion chamber and is enclosed by an extra jacket, disposed at a distance from the flue, for heating up circulating in¬ door air. By this means a higher temperature is maintained at the flue, whereby the upwards flow of flue gases or the draugh will become stronger than is usually the case with, for ex¬ ample, open stoves. This causes a fast removal of the flue gases out to the outdoor air, at the same time the stove burns fiercely, which in turn causes poor utilisation of the thermal energy of the fuel and the hot flue gases, but above all, in¬ complete combustion results, which causes emission of a large quantity of toxic gases, solid particles and the like. The formation of cracks, particularly in the combustion chamber walls and often after only a short period of use are normal occurrences in the case of known heating stoves.

The solution: The afore-mentioned inconveniencies in the case of know heat¬ ing stoves are, however, eliminated in the heating stove in accordance with the invention at the same time as it exhibits further advantages. Combustion is thereby damped and the stove burns gently at the same time as the flames are forced towan¬ der across the hearth and are spread out by means of a flame spreader, which together with the shape of the combustion cham¬ ber ensures a considerably large quantity of flames. Due to the better utilisation of the fuel and the flames, the fuel lasts considerably longer despite the greater amount of ther¬ mal emission obtained from the fire, compared to an equivalent size of stove or fuel quantity in the case of current stoves where, among other features, the flames continually flare up and strive towards the flue to allow the flue gases to leave quickly. In the case of the heating stove in accordance with the invention a cer^'tain quantity of fuel thus provides more energy that can be utilised for room heating. This further means that the heating stove can be made of small dimensions with a small hearth, to cover the intended requirement. The

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OMPI slow combustion of the fuel and the spreading of the flames and their quiet movement, but, perhaps above all, their spread¬ ing out and high temperature cause those toxic gases to which combustion gives rise, to be consumed in the hearth. In the case of the heating stove in accordance with the invention, virtually no emission of toxic gases together with the flue gases occurs. The favourable utilisation of thermal energy from the flue gases further causes them to have a relatively low temperature on emission. When the heating stove_is used as an open stove, i.e. without the combustion chamber being closed off by doors or the like, a considerably higher emission of radiated heat from the fire is achieved than in the case of current open stoves and heating stoves at the same time as the system of hot a^"ir circulation can be utilised. A heating stove in accordance with the invention is hereby characterised in that at least one of the afore-mentioned side walls which limit the combustion chamber, and the rear wall which may be present, display a corrugated surface as well as the fact that the flame spreader or its holders are connected to the rear wall, which may be present, and the lateral walls, some distance, however, along the lateral walls from the doors or the like, and di¬ vides the combustion chamber into a lower^' chamber below the flame spreader, intended to serve as a combustion chamber and an upper chamber above the flame spreader, whereby the upper and lower chambers communicate with each other via an opening formed between the doors or the like and the front edge of the flame spreader. Another characteristic of the heating stove in accordance with the invention is comprised in that the lateral walls which limit the combustion chamber, and the rear wall, which may be present are comprised by a liner, disposed in the combustion chamber and all of whose walls may exhibit a cor¬ rugated surface. A further characteristic of the heating stove in accordance with the invention is comprised in that the cas¬ ing of the stove consists of two cover plates, disposed at a distance from each other preferably parallel, between which an air gap is disposed.

Brief description of drawings: Further characteristics and advantages of the heating stove in accordance with the invention can be seen, in the follow¬ ing description, from examples of execution, whereby at the same time reference will be made to the enclosed schematic drawings, of which, Fig. 1 shows a lateral view of an exam¬ ple of execution of a heating stove in accordance with the invention and with or without a liner, in a section. Fig.2. shows the heating stove in accordance with figure 1 in a cross-section along the line II-II in figure 1 and with a lin- er in accordance with one form of execution, Fig. 3 shows a cross-section of a heating stove with a liner in accordance with another form of execution, Figs. 4-6 show from above sec¬ tions of a jacket, namely, lateral walls and rear wall, under respectively upper side and Figs. 7 and 8 show from one side, respectively, from above a composite jacket with flue and air circulation ducts fitted and with a partially fitted fresh air duct.

Mode of carrying out the invention: Using reference designation 1 in Figure 1 a heating stove is shown with a casing 2. The casing 2, refer also to figure 2, comprises rear 5, sides 6, upper side 7, front 8, doors or the like 9, as well as a stand 10 which may be comprised of a stand with legs, a sheet-metal casing with a plinth or the like. The afore-mentioned sides, 5, 6, 7 and 8 consist of two cover plates, 3, 4, disposed at a distance from each other and preferably parallel, for example, a metal plate which forms the outer casing 3 of the stove and an inner aluminium plate 4, whose lateral surfaces facing the interior of the stove are disposed so as to be reflective. An air gap 34, is disposed between these cover plates 3, 4. It is unnecessary to utilise any special insulating material in order to keep the outside of the stove cool, since it has been demonstrated that this design with double cover plates and an air gap produces a • stove with a more than sufficiently cool exterior. The absence of any special insulation material ensures in addition to the advantages mentioned by way of introduction, a contributory factor in the stove being able to possess a low weight. The stove 1 displays further a combustion chamber 11 which shows lateral walls 12, 12', a rear wall 13, 13', an upper wall 14 and a lower wall 15, as well as front sections 16, which may be present. With reference to figures 4 - 7, it can be shown that the combustion chamber is. comprised of a jacket 55, comprising a metal plate 45 (figure 4) , bent round prefer¬ ably in one piece, and forming lateral walls 12 and a rear wall 13, a lower and an upper wall, 15 respectively 14 (fig¬ ures 5 and 6) , which walls are attached to each other,e.g.by means of argon welds and form a chamber which can be closed off by means of doors or the like. At least one of the lat¬ eral walls 12 or the rear wall 13 or preferably all thesewalls are produced so as to possess a corrugated surface 44, where¬ by the formation of cracks in the combustion chamber is pre¬ vented, since the walls during heating call utilise a "con¬ certina" effect, i.e. they can expand thermally without ex¬ cessively large strains occurring in the walls and their joints. The front edge of the lateral walls 12 displays narrow wall sections 46, which are intended to be connected to the front section of the stove or the casing 2. Other wall sections are disposed at a distance from the casing 2 of the stove, where the chamber 37 is formed for the circulation of air for heat¬ ing. A hole 48 is disposed in the lower wall 15 to allow the passage of a fresh air supply to the fire. The upper wall 14 displays a hole 47 for the emission of flue gases and is con¬ nected to a flue 19.

In order to achieve a further degree of safety and the possi¬ bility of replacing parts which are subjected to great stress, the combustion chamber 11 or a section of it, which comprises the hearth 56, itself, can be fitted with a liner 17 whose end edge sections 18 are connected to the lateral walls 12 of the jacket 55. The liner in accordance with the figure 2 shows a corrugated surface 44', corresponding to the jacket corruga¬ tion 44, but which is disposed with its lateral walls 12' and the rear wall 13' at a distance from the jacket so that an air gap is formed between the jacket and the liner. The liner 17 can be connected to a flame spreader 20 disposed and extend¬ ing down to the bottom wall 15 or down to an ash box 33. Figure 3 shows a somewhat differently shaped liner 17. The liner thus abuts each other fold line 54 in the lateral walls 12 of the jacket 55, in order therebetween to leave an air gap between the liner and the jacket. The rear walls of the jacket and the liner, 13 and 13' respectively, can be fitted with corresponding corrugated surfaces. Here the hole 21 in the flame spreader is circular. By making the hole rectangu¬ lar or square, material savings are made in the construction of the damper 22.

The flame spreader 20 or its holders 50 are closely connected to the rear wall 13, 13' and the lateral walls, 12, 12', along the lateral walls, however, at a distance from the doors 9 or the like and divide the combustion chamber 11 into a lower chamber 51 below the flame spreader, and intended to comprise the combustion chamber 56, itself, and an upper chamber 52 above the flame spreader. The lower and upper chambers com¬ municate with each other via opening 53, formed between the doors 9 or the like, as well as between the front section of the stove and the front edge 26 of the flame spreader 20. The flame spreader forces the flames to turn, whereby they wander downwards in the hearth 56 at the same time as they swell out and move slowly. A downwards facing edge 24 which may be pres¬ ent, and is shaped on the front edge 26 of the flame spreader can further assist in forcing the flames downwards and forc¬ ing the flue gases to make a detour. An identical but upwards facing edge 25 may be disposed on the control rod 23 of the damper 22. As has previously been shown, the flame spreader displays a.damper 22, which is used when the fire is first lit, then it is closed and normally kept closed whilst the stove is being utilised. The calm and cooling effect on the flames is achieved even if the damper is disposed somewhat open but in so doing heat is, of course, lost, which can flow directly into the flue 19. Flames and flue gases are enclosed in the hearth 56 below the flame spreader 20 if its damper is shut and these flue gases communicate with the upper chamber 52 and the flue, solely via the opening 53. The flame spreader 20 can consist of a thin plate with bent-over edges and be in- serted in its holders, which fill up the corrugated surfaces. The damper 22 can be comprised of another plate or cover sheet, which is disposed so as to be able to slide on the flame spread¬ er.

The upper wall 14 of the jointed jacket is located at some distance from the upper side 7 of the casing 2, so that a gap is disposed between the casing and jacket, whereby circulat¬ ing air for heating can cool down these surfaces and the flue gas pipe 19. A second casing 32 is disposed around the flue pipe, and extends from the first casing 2 and is disposed so as to form a channel 39 between the inside of the second cas¬ ing and the flue pipe for the air for heating which is inten¬ ded to circulate through the stove. The second casing 32 here- by displays one or several outlets 40 for heated air and which outlets can communicate with pipes or the like to transport the heated air to other rooms. In order to cool the flue gas pipe better and thus better utilise thermal energy, the flue pipe can be fitted with flanges 49 which protrude outwards and along the flue pipe, see figure 8.

The air for heating is sucked into the stove through natural openings in the frame 10 of the stove or through specially disposed openings in the lower section of the stove, refer to the arrows 41. The air then passes through the exterior of the jacket 55, cools the lateral walls 12 and the rear wall 13, which may be present, and the upper wall 14, and, of course, the bottom wall 15. The air then cools the exterior of the flue gas pipe to pass out as warmed air into the room outside the stove or into piping connected to the stove.

In order to realise a faster throughflow or that of a larger quantity of air for heating, a fan 27 is disposed and prefer¬ ably horizontally at some distance below the bottom 15 of the hearth in the stove casing or stand 10. The fan 27 is in ac¬ cordance with the invention so as to be speed-regulated and is controlled by a control device 28. This control device com¬ prises a sensor element 29, which detects the temperature of the air outside the stove 1, as well as a printed circuit as-

O FI sembly 30 with necessary and in themselves known electronic control functions and a sensor body 31, which is disposed next to the hearth 56, itself, or between reflector plate and hearth and detects the temperature of the fire. By this means the fan can be made to carry out a throughflow of air so that a predetermined or preset temperature in the room outside the stove 1 can be kept constant or somewhat constant. Without the control device an often uncomfortable excess temperature is too easily attained in the room. The control device is further disposed in such a manner that when the fire is out the fan is switched off.

One or several fresh air ducts 35 are disposed between the flue 19 and the second casing 32 and communicate with the out- door air and extend to below the bottom 15 of the hearth or combustion chamber and open via a damper 36 into the combus¬ tion chamber 11 in front of the hearth 56. The air supplied can also be allowed to be discharged below the hearth and is supplied to the fire from below. The damper 36 can be regu¬ lated by means of an operating unit 38. The fresh air supplied is thus pre-warmed. The arrows 42 show the path of the addi¬ tional air into the fire.

The flue gases pass via the opening 53 in front of the flame spreader 20 and the upper chamber 52 in the combustion cham¬ ber, out through the flue 19, refer to the arrows 43.

Industrial applicability:

Manufacture of this heating stove can be carried out at a rel¬ atively low cost, because it is simple to produce and is forme basically by assembled and joined metal plates and pipes. This heating stove is utilisable anywhere where rooms are to behea ed, such as in living-quarters, storage and work-rooms, assem¬ bly rooms, working and storage premises, etc. Any combustible material whatsoever can comprise the fuel.

Tests have shown that the combustion of 2 kg of firewood per hour yields 8 kW, 4 kg of firewood yields 16 kW and 6.5 kg yields 24 kW. The emission of toxic gases with the flue gases was lower than 0.3% as compared to a normal value of 10%. The temperature of the flue gases could be kept as low as 200°C. The utilisation of a control device for the fan enabled the temperature to be held virtually constant at 23°C in the test premises. These surprising values are due to the design of the stove in which among other features, the flames can be util¬ ised more due to their being spread out and widened.

Without exceeding the framework of the inventive idea, modi¬ fications of the heating stove described and shown should be possible. The exterior of the heating stove can thus display a different design and the heating stove can be designed to comprise a corner stove, a wall stove or a free-standing stove. The shape of the combustion chamber can ary _ana, for example, the chamber and thus the jacket and walls present can be with¬ out the rear wall, i.e. that the lateral walls can be disposed so as to radiate together in an acute angle or that the lat¬ eral walls are shaped so as to have multiple edges or in the shape of a circular arc. The use of a corrugated liner in ac¬ cordance with the invention does not exclude the use of a heat¬ ing stove in accordance with the invention with a jacket lack¬ ing any corrugated surfaces. The downwards and upwards point¬ ing edges which are disposed in the combustion chamber, ad¬ jacent to the opening between the lower and upper chambers can exhibit a.- different extension and do not need to extend completely across the chamber. The downwards pointing edge thus causes the fire to widen. The corrugated surfaces can display a different shape and can instead be waved without folds.The fan can be disposed as a thyristor-controlled speed- regulated fan. Fuel relates primarily to firewood or other solid combustible materials, such as various types of briq¬ uettes, compressed paper waste, etc. It is however not ex¬ cluded that the heating stove in accordance with the inven¬ tion can be utilised in the use of liquid or gas fuels. The heating stove in accordance with the invention is those not restricted to the given examples of execution but solely by the patent claims hereinafter.

OMPI

Claims

Patent claims:

1. A heating stove (1) for heating air circulating through the stove and comprising a first casing (2) , a combustion chamber (11) , disposed in the casing and able to be sealed off by means of doors (9) or the like, which combustion chamber is limited by at least lateral walls (12, 12') disposed in the casing (2) and a rear wall (13, 13'), which may be present, a duct (19) disposed for the removal of flue gases, a flame spreader (20) which displays a front edge (26) which faces the doors (9) , or the like, as well as a fan (27) , which is disposed in order to be able to increase the throughflow of air, characterised in that at least one of the afore-mentioned walls (12, 12', 13, 13') displays a corrugated surface (44, 44') as well as that the flame spreader (20) or its holders (50) are connected to rear wall (13, 13"), which may be pre¬ sent and the lateral walls (12, 12'), along the lateral walls, however, at a distance from the doors (9) or the like and di¬ vide the combustion chamber (11) into a lower chamber (51) be¬ low the flame -spreader (20) intended to comprise the hearth (56) and an upper chamber (52) above the flame spreader (20) , whereby the upper and lower chambers (51 and 52) communicate with each other via an opening (53) formed between the doors (9) or the like, and the front edge (26) of the flame spread¬ er (20) .

2. A heating stove in accordance with claim 1, characterised in that the afore-mentioned walls (12, 12', 13, 13') are in¬ cluded in a mantle (55) disposed in a casing (2) which mantle in addition to lateral walls (12) and a rear wall (13) , which may be present, also exhibits upper and lower walls (14 and 15 respectively) as well as front sections (16) , which may be present.

3. A heating stove in accordance with claim 2, characterised in that the lateral walls (12) and the rear wall (13) , which may be present, are fitted with a liner (17) , which exhibits corrugated surfaces (44¹) which correspond in essence to the corrugated surfaces (44) of the lateral walls and the rear wall, which may be present, whereby the liner (17) is dis¬ posed either at a distance from or in certain sections, in abutment with, the lateral walls (12) and the rear wall, which may be present, whereby the liner in- abutment against the lat¬ eral walls and the rear wall, which may be present, is dis¬ posed so as to abut, for example, only along each second fold line (54) .

4. A heating stove in accordance with claim 1, characterised in that the afore-mentioned walls (12', 13') are comprised by a liner (17) disposed in the hearth (56) or the combustion chamber (11) .

5. A heating stove in accordance with claims 2, 3 or 4, char¬ acterised in that the afore-mentioned walls (12, 12',.13, 13') are constructed with corrugated surfaces (44 and/or 44").

6. A heating stove in accordance with claims 2 or 3, charac¬ terised in that the lateral walls (12) of the jacket (55) and the rear wall (13) , which may be present, is comprised of a metal plate (45) , which is preferably bent in one piece and is disposed so as to be connected to the front section of the stove (1) by means of relatively small wall sections (46) and be disposed at a distance from the casing (2) of the stove by means of other wall sections, as well as the upper wall (4) which in the present case can comprise a section of the afore¬ mentioned front sections (16) .

7. A heating stove in accordance with claim 1, characterised in that a second casing (32) is disposed around the flue (19) which protrudes out from the first casing (2) and is further disposed to form a channel (39) between the inside of the cas¬ ing and the flue for the air which circulates through the stove

OMPI and is to be heated up, whereby this second casing (32) ex¬ hibits one or several outlets (40) for heated air.

8. A heating stove in accordance with claim 7, characterised in that one or several fresh air channels (35) are disposed so as to extend between the duct (19) and the second casing (32) , which channels communicate with the outdoor air and ex¬ tend below the bottom (15") of the hearth or the combustion chamber and open into the combustion chamber (11) in front of the hearth (56) .

9. A heating stove in accordance with claims 1 or 7, charac¬ terised in that the fan (27) is disposed so as to be speed- regulated and is controlled by a control device (28) compris¬ ing a sensor element (29) , which detects the temperature of the air outside the stove (1) , a circuit board assembly (30) with necessary control functions as well as a sensor body (31) which is disposed adjacent to the hearth (56), itself, and detects the temperature of the fire.

10. A heating stove in accordance with claim 1, characterised in that the casing (2) of the stove (1) consists of two cover plates (3 and 4) disposed at a distance from each other and preferably parallel, between which in this manner, a heat-in¬ sulating air gap (34) is disposed.

' O PI