Technical field:

The present invention relates to a method for the combustion of fuels in heating stoves displaying at least one front hatch, whereby the heat- ing stove displays a fireplace with a hearth and ducts that communicate with a flue or an exhaust pipe, whereby a first duct or equivalent is disposed for discharge of flue or exhaust gases or residues thereof to the said flue pipe, which is disposed for discharge of the said, flue gases or equivalent from the heating stove. Background:

There is a need for heating stoves, in which flue and other exhaust gases produced are eliminated or reduced to a minimum for suppres¬ sion of impermissible emissions of flue gases constituting a public nuisance. There is a furthermore a need in heating stoves for a better method of utilisation of the heating eaergy generated for the heating of the rooms. For the purposes of heating, a long burning time is desirable in the stove, and in order to utilise the heating energy generated by the heating stove, the air in room should circulate through the heating stove, which circulation should.be able to be controlled in order to make good use ^" of the heating energy generated.

Technical problems:

Known heating stoves of the type in question do not fulfil the require¬ ments in respect of exhaust gas emissions which are today being made with increasing frequency, especially with respect to their installation and use in heavily built-up areas. Thus the flue gases generated are discharged from the fireplace by being allowed to rise upwards in the combustion chamber and pass through a flue pipe which is disposed above the combustion chamber, whereby the in et of the flue pipe is disposed above the hearth. Moreover, known heating stoves can only be supplied with a limited amount of fuel and thus require frequent filling with fuel during long-term heating.

The solution:

The utilisation of a procedure in accordance with the present invention

fulfils, however, the requirements made and suppresses the nuisances caused by the known heating stoves. Utilisation of the procedure in accordance with the invention further confers a number of other ad¬ vantages, which include a safe and optimum utilisation of the heat- ing stove also as a source of heat for heating purposes. Futhermore, the heating stove can be manufactured in a simple and safe way and at low cost, the latter contributing towards a readily available source of energy for energy conservation measures and one that .is also easy to install. Naturally, the heating stove also fulfils such aesthetic requirements such as increased well-being and the like. In addition, the efficiency of combustion can be utilised in a more efficient manner and thus be better employed for the purposes of heating. The procedure in accordance with the invention is char¬ acterised in that a second duct is disposed, which communicates with the flue or exhaust pipe and leads to the fireplace of the heating stove. In order to utilise the energy from the heating stove to heat the air in the room or to achieve purification of the flue gases or exhaust gases or residues thereof during the combustion of the fuel, the front hatch of the heating stove is closed, whereby a damper is made to cover or shut off the said second duct and the said flue gases or equivalent arethereby made to pass through the hearth of the fire¬ place or a bed of embers achieved on the hearth and are led to the first duct for discharge of the flue gases or equivalent to the said flue.

The invention also relates to a heating stove for the implementation of the said procedure, whereby the heatingstove comprises both a com¬ bustion chamber, in which a fireplace with a hearth shall be disposed, and first and second ducts, which are disposed to communicate with the combustion chamber and a flue or exhaust pipe, which is disposed or shall be disposed for discharge of the flue or exhaust gases or re- sidues thereof from the heating stove, whereby the combustion chamber displays a bottom, lateral walls and an open side towards the front side of the heating stove, which open side can.be covered by one or more front hatches. The heating stove is characterised in that the said hearth is intended to be disposed at a distance from the bottom of the combustion chamber, whereby one of the said lateral walls

displays an aperture below the hearth which leads to the said first duct or to a chamber, in which one end of the said first duct opens, while the one end of the said second duct opens into the combustion chamber above the hearth and displays a damper, which is disposed to be able to cover or close the said second duct when the front hatch is closed.

Brief description of the the drawings:

Additional characteristics of and advantages of the procedure and the heating stove in accordance with the invention will be apparent by embodiments in the. descriptive text hereinafter, whereby simulta¬ neous reference will be made to the .accompanying schematic drawings, of which Fig. 1 illustrates a front view of one embodiment of a heat¬ ing stove in accordance with the invention, in which parts of a front casing or outer cowling have been removed to ensure greater clarity, Fig. 2 illustrates on a larger scale a horizontal section taken along the line II-II through the stove illustrated in Fig. 1, Fig. 3 illu¬ strates in a perspective view one part of the fireplace, Fig. 4 il¬ lustrates a catch device, Fig. 5 illustrates a regulating arrangement for a damper, Fig. 6 illustrates another example of an embodiment of a heating stove in accordance with the invention, Fig. 7 illustrates a horizontal section taken along the line VII-VII through the heating stove illustrated in Fig. 6, Fig. 8 illustrates from above a hearth, which shall be disposed in a combustion chamber, Fig. 9 illustrates from the front a heating stove without a casing, Fig. 10 illustrates from one side the heating stove illustrated in Fig. 9, and Fig. 11 illustrates in a perspective view a heating stove in accordance with the invention in an X-ray photograph, whereby components of the heat¬ ing stove are apparent.

Best mode for carrying out the invention: The reference designation 1 in Figs. 1, 6 and 11 illustrates one em¬ bodiment ofheating stoves in accordance with the invention with a casing 2 or outer cowling, which on the forward or front side of the heating stove can be formed with easily removable cowling hat¬ ches 63 as well as preferably hinged casing hatches 64 for ease of access to the interior of the heating stove. In accordance with the

embodiment the front side of the heating stove isprovidedwith front hatches 3 for closing off the combustion chamber 58, whereby the front hatches 3 are providedwithclosing devices 4, which are provided with an opening handle, which is placed so that it is kept cool by the inward flow of the combustion air. As will be apparent from Fig. 2 the front hatches 3 can be disposed with outer and inner hatches, whereby the inner hatches 3' are formed of perforated sheet metal, which radiate the heat from the combustion chamber 58 back into the combustion chamber and which keep down the external temperature of the outer hatches. The outer hatches can be formed of toughened glass. Since the combustion air is admitted at the lower front edge of the combsution chamber and below and above the front hatches, the front hatches can be kept free of soot deposits. A flue 20 leads from the heating stove and can comprise a part of the heatingstove or its casing, but should comprise a communication duct from the heating stove and to the open air.

The combustion chamber 58 displays a fireplace 5 as well as a hearth 6 for the combustion of the fuel and a grate 7, which comprises5 part of the support for the fuel and is providedwith agrill 27, for ex- ample, in the form of one or more bars, through which ash and slag : can fall down into an ash space 8, which can beprovidedwithan ash box or ash hatch. The fireplace or hearth includes flat surfaces 26 set at an oblique angle to each other, which contribute towards the fuel, bed of embers and ash being collected in a central section of the fireplace or grate 7, i.e. that a relatively narrow, concentra¬ ted bed of embers is obtained. The glowing embers thereby produced can be better utilised for the flue gases so that the latter really do pass through the bed of embers and primarily through the hot part of the bed of embers to achieve optimum combustion of the flue gases. The obliquely set flat surfaces 26 also form upper walls for air ducts 33 for leading air to the bed of embers, see Fig. 3. The air ducts 33 are further delineated by a lower wall and a lateral wall, which can be comprised by a wall 19 in the combustion chamber 58 or the fireplace 5. The obliquely set flat surfaces 26 are formed of sheet metal plates which can be folded to form a second lateral

wall 31 in the air ducts 33 and which second lateral wall 31 can be provided, with one or more apertures 32, for example, in the form of through holes in the wall. By disposing one or more such aper¬ tures 32 and perhaps especially in the area far or furthest inside the fireplace 4, there is thus achieved a more even combustion of the fuel in the depth of the fireplace 5. This design of the air ducts 33 simultaneously attains a cooling of the sheet-metal mate¬ rial in the hearth, whereby a cooling may be desirable primarily on the obliquely set sheet-metal plates 26, which can thus obtain a longer life.

From the space 8 below the firespace 5 or the hearth 6 there is disposed a passage 9 to the flue ducts 10, 11 of the heating stove, which open into or lead to a soot box 12 with a soot hatch 13 to allow the soot box to be emptied. The part of the flue ducts loca- ted close to the fireplace can display a box shape 10, which can display an extension in the entire height and breadth of the com¬ bustion chamber, whereby large heat conduction surfaces are achieved. By this means the heat generated by the fuel and the flue gases can already be made use of in this part of the heating stove 1 and where the degree of combustion efficiency is best. The remaining part 11 of the flue ducts 10, 11 can, for the purposes of attainng large heat conduction surfaces, be comprised of several flues, for example, three pipes, which lead from the box 10 or the combustion chamber 58 and to the flue 20 or the intermediately located soot box 12. Above the soot box 12 the casing 2 is preferably shaped with venti¬ lation apertures, for example, in the form of a grille, which has been marked only with reference designation 21 in Fig. 1. In the casing or in a plinth 22 fitted to a heating stove 1 there can thus be dis¬ posed where required a fan 23 for circulation of air through the heating stove 1 for heating the room air in the area or building in which the heating stove 1 is located. The room air heated by the heating stove 1, its casings and flue ducts 10, 11 is emitted through the casing of the heating stove by means of the ventilation grille 21 or pipes connected to the heating stove, which can lead heated air to other areas or areas located far from the heating stove.

The ventilation grille 21 is preferably located at a high level in the heating ±ove 1 so that the heated air which is admitted at the bottom of the heating stove flows out at a safe, high level. The amount of warm air which is required at various times can be re- gulated by a thyristor 25 disposed in the heating stove, refer to the illustrated control panel, which is disposed at the front of the heating stove and which is also fitted with a main switch 24 for the fan 23. The thyristor 24 can be disposed for infinitely variable regulation of the warm air. As will be apparent from Fig. 2, the heating stove can be fitted with double casings, i.e., both the outer cowling 2 and an insulat¬ ing jacket 29, which is disposed at a distance from the outer cowl¬ ing 2 and forms a duct 30 or space between the outer and inner cas¬ ings, which are preferably formed on accessible parts of the heat- ing stove and in its vertical plane. The duct 30 can be fitted with a plurality of cooling flanges. Duct 30 however lacks insulation mate¬ rial, whereby the lack of the mineral wool insulation usually pre¬ sent confers several advaπatages, and among them that no tufts of mineral wool whatsoever can be entrained in the air circulation through the heating stove. Moreover, it is a decisive advantage from the point of view of industrial safety that the handling of mineral wool for insulating heating stoves is dispensed with. The lower part of the heating stove and that which is located above its plinth 22 can be shaped as a box-shaped jacket 28, which at least partially can comprise said insulating jacket of the heating stove, but is preferably disposed at a distance from the insulating jacket 29, especially in respect of the area around the actual com¬ bustion chamber 58 and in particular around the flue duct 10, so that there is room for the room air to sweep past the heated heat conduction surfaces and be heated.

In accordance with a special embodiment of the heating stove in accordance with the invention, it is thus designed with automatic fuel filling and comprises a fuel store. Hence, a duct 14 extends from the combustion chamber 58 and the fireplace 5 in the vertical plane of the heating stove, whereby filling with wood, coal or

briquettes can be done through a filling hatch 15. Hence, a stack of fuel can be disposed in heating stove so that it obtains a long burn¬ ing time, since it gradually consumes the fuel in the fuel stack. A drying of the. fuel is simultaneously achieved. In order to ensure the filling with fuel and its supply to the fireplace5 _t the duct 14 can be made somewhat sloping or with at least one sloping wall 19, whereby any risk of the fuel being wedged tight or similar is pre¬ vented. Furthermore, the sloping flat surfaces 26 ensure fuel and glowing embers to the central part of the fireplace 5 and to the bed of embers.

The casing 2 can also be comprised by a simple casing or cowling, which is disposed at a distance from a jacket, see Figs. 7, 9 and 10. The jacket is thus comprised by the combustion chamber section, the chamber 10, the ducts 10, 11 and 14, the soot box 12, a part of a flue or exhaust pipe 20 as well as flanges 67, 68 around the front edge of the combustion chamber 58. The casing 2, likewise the front hatches 3, can be attached to said flanges by means of attachment devices 70 in hole 69.

The combustion chamber 58, the chamber 10 or the after-combustion chamber and heat exchanger in the form of the ducts 10 and/or 11 are made of sheet stainless steel.

It will be evident from Fig. 1 that the duct 14 communicates with the flue 20 and leads from the combustion chamber 58 and opens into the soot box 12. Access to the interior of the duct 14 can be ob- tained through the filling hatch 15. Above the filling hatch 15 there is disposed a damper 16, which by means of a damper regulat¬ ing device 17 is regulatable from the outside of the heating stove, or in accordance with a special embodiment of the invention, is in communication with the front hatches 3. Moreover, there is illus- trated in the figures a catch device 18 for the said filling hatch 15.

Thus the heating stove in accordance with a special embodiment isprov- vided- with an automatically operating regulating device 17 for the damper 16. The regulating device acts in such a manner that when

the front hatches 3 are open or opened, then the damper 16 opens automatically or is open, respectively, which allows a free outlet for the flue gases or equivalent to the free air through the flue 20. Such a regulating device 17 will be apparent in Fig. 5 and in- eludes a regulating element in the form of a lengthwise extending rod 34, which via a joint 35 in its upper end gives way to a second rod 36, which is in turn articulated in the damper 16. The length¬ wise extending rod 34 is fitted at its other end with an element 37, for example, in the form of a disc, which is articulated around an axle 39 or equivalent. From the element there leads a third rod 38, which protrudes beyond the casing 2 of the heating stove in order to abut the hatches 3. By means of an excentric bearing arrangement of the element 37 and the rods 34, 38, considerable regulating movements are ensured in the arrangement, whereby the element 37 moves in the directions of.the arrow. The hatches 3 thus keep the said third rod 38 depressed and actuate the element 37 and the rods 34 and 36 so that the damper 16 is kept shut and closes the duct 14. It is desirable to keep the damper shut in order to obtain a natural draught through the bed of embers, where by the flue gases or equivalent pass through the hearth 6 and the bed of embers and to the flue 20 via the space 8 and the flue ductsJO, 11. When the hatches 3 are opened the length¬ wise extending rod 34 will actuate the element 37 due to its own weight and cause it to rotate, whereby the damper 16 is opened and said third rod.38 protrudes further beyond the casing 2. When the hat- ches 3 are closed the hatches push the said third rod 38 and the element 37 moves in the opposite direction, whereby the damper 16 closes the duct 14. A further advantage of the automatic regulating device 17 is that when the front hatches 3 are opened, there is ob¬ tained an overpressure around the filling hatch 15, whereby there is no risk of flue gases coming out around the hatch. Otherwise it is necessary to rely on a good seal between the filling hatch 15 and the wall of the duct 14. When the front hatches 3 are opened, an underpressure is created at the filling hatch 15, which means that there is no risk that any flue gases will force their way out around the filling hatch. Any flues gases present are instead led _U p to the soot box 12 or the flue ducts and out through the flue 20.

The lengthwise extending rod 34 in the regulating device 17 can display a bent shape or several bent portions. During combustion in the heating stove 1 the jacket lengthens on account to the ther¬ mal expansion, for which reason the regulating device 17 is formed in this manner in accordance with a second embodiment, in order to achieve this automatic regulation. The lengthwise extending rod 34 hereby functions as a bending or compression spring and may also be disposed in order to close the damper against the action of an opening spring 57 disposed for the damper. The opening spring opens the damper when the front hatches 3 are opened or open. In the clo¬ sure of the front hatches 3 the lengthwise entending rod 34 is made to bend further and attain tension and depresses the damper 16 against itsseat. The damper 16 is thus controlled by the front hatches 3 through their opening and closing, which is an advantage for simple handling of the heating stove 1.

There is however a risk present with a.utilisation of a fuel store and automatic fuel filling in a heating stove, whereby there must be an opening to a duct which has direct communication with the combus¬ tion chamber. In accordance with the embodiment the opening isthus closable by a hatch at the same time as the damper 16 in the duct 14 must be disposed above the filling hatch 15. If the opening is kept open or left open and forgotten simultaneously with combustion of fuel, this can result in flue gases from the heating stove being able to flow out into the room or building in which the heating stove is located. The automatically acting regulating device 17 for the damper 16 hereby also acts so that no flue gases force their way out through the opening in the duct or around the filling hatch 15. When the front hatches 3 are open then the damper 16 is open with a free outlet via the flue for the flue gases or equivalent. When the front hatches 3 are closes the flue gases or equivalent pass through the hearth 6 and the bed of embers and on to the flue 20.

In accordance with a further special embodiment of the heating stove in accordance with the invention the heating stove can be provided with catch devices 18 for the filling hatch, which catch devices coact with the front hatches 3 so that only one of the hatches -

the filling hatch 15 or the front hatches 3 respectively - can be opened at any one time. This thus prevents, for example, the front hatches 3 from being opened simultaneously as the filling hatch 15 is open, which should mean that one eliminates the risk of flue gases, soot and the like being able to gain access to a living area. A simple embodiment of such a catch device 18 is apparent in figure 4. The arrangement thus includes a lengthwise extending catch rod 41, whose one end 42 can be inserted to engage with the filling hatch 15, for example, through a recess 43 or a hole at the lower edge of the hatch, and its other end 44 in engagement with the front hatches 3 or one front hatch, whereby its end is inserted in, for example, a recess 45 or a hole in the front hatch. There is disposed on the casing 2 of the heating stove a fitting46, likewise a fitting 46 on the wall of the duct 14. The fittings 46 are included in or hold catch elements, which in their simplest form consist of a pin 47, which can be displaced against the action of a spring 48. The lengthwise extending catch rod 41 should always be in engagement with one of the hatches 3, 15 and during, for example, opening of the filling hatch 15 the catch rod 41 is thus moved out of its en- gagement with the hatch 15 and, for example, against the action of a spring 51. The end 49 of the pin 47 has thus abutted the catch rod 41, but when the catch rod 41 is moved to one side, the pin 47 can be pushed out, its end 49 preventing the _. catch rod 41 from re¬ turning. Simultaneously as the catch rod 41 is moved out of engage- ment with the filling hatch 15, the catch rod is made to push down to engagement with the front hatch 3 so that the end 44 of the catch rod 44, which end has previously abutted the pin 47, is now inserted in the recess 45 in the front hatch. The pin 47 will thus abut the catch rod 41. In the closing and locking of the filling hatch 15 the pin 47 is moved to one side so that the catch rod 41 can spring back to engagement with the filling hatch, whereby the front hatch 3 is automatically released from the engagement of the catch rod 41 with the front hatch3 and the pin 47 of the adjacent catch ele¬ ment pushes out and ensures that the catch rod 41 cannot be moved out of its engagement with the filling hatch 15.

Hence one can open the front hatches 3 during combustion of fuel without risking any leakage whatsoever of flue gases and the equi¬ valent out into the room, since when the front hatches 3 are opened then the damper 16 is also opened. By means of the present embodiment the filling hatch 15 is closed automatically by the automatically acting catch device. Furthermore, when the filling hatch 15 is opened, the front hatches 3 are locked automatically. When the front hatches are closed, an underpressure is created in the heating stove and the flue gases, likewise the flames are led in the customary manner through the hearth and the bed of embers.

As will be apparent from Fig. 9, the hearth 6 divides the combustion chamber 58 in a fireplace section 5 and a space 8 below the hearth 6. The hearth 6 can be disposed and be removable from the combustion chamber 58 and can display a sheet-metal plate 65 with air holes 56 as well as a centrally located aperture 66 throuqh the plate that is provided with a grate 7, which can be, like the previously described grate, lift- and/or rotatable in order to faciliate the passage of ashes accumulated on the hearth therethrough. Flanges 50 comprise stop devices for obliquely set plates 26, which rest against lateral walls 54 of thefireplace5. The combustion chamber 58 and also the bottom and lateral walls of the box 10, or in accordance with the latter embodiments the chamber 10, can be provided with a lining 59 of, e.g., refractory bricks, whereby the wall 55 of the com¬ bustion chamber 58, below the hearth 6, i.e. in the space 8 is com- prised by the lining 59, which also delineates the aperture 9 be¬ tween the combustion chamber 58 or the sapce 8 and the duct 11 or the chamber 10 in that the lining extends only partially towards the front of the heating stove or its front hatches and leaves an aperture of, e.g., half the depth of the combustion chamber 58. The combustion chamber 58 also displays a bottom 53, which extends into the chamber 10.

The heating stove 1 can display a spark guard 60, which can be moved to one side and is joined to the heating stove and can be disposed in front of and covering a part of the fireplace 5.

The dimensioning of the heating stove in accordance with the inven¬ tion ensures an underpressure and a powerful draught through the bed of embers, whereby an effective combustion of the flue gases is a- chieved and at such high temperatures as are necessary for combustion of the flue gases.

Heating of the room air takes place is that the air is admitted through the casing, for example, through one or both sides 61 of the casing 22, which sides can be provided with dust filters 62. The air subsequently flows upwards between the combustion chamber and heat exchanger and the casing 2 and then out through the outlet 21 or an outlet aperture 21 provided with a grille. The air is con¬ veyed by, for example, an axial fan 23, whereby the speed of the fan can be varied in an infinitely adjustable manner. The circula- tion of the air through the heating stove 1 will be apparent from Fig. 11, which is shown by the arrows 71 and 72.

In combustion of the fuel the front hatches 3 are kept closed, whereby the damper 16 in the duct 14, which is located as an ex¬ tension upwards of the fireplace 5 or the combustion chamber 58, shuts or closes the dut 14 automatically. By this means the seat of the fire with flue gases and other exhaust gases will pass through the hearth 6 and the bed of embers achieved thereon, whereby an ef¬ fective combustion and purification of the flue gases or equivalent will be obtained, especially due to the concentrated bed of embers with its consequently high temperature. The arrow 74 shows the di¬ rection of the seat of the fire and the flue gases or equivalent and their path through the heating stove 1 from the hearth 6, whereby theseat of the fire sweeps down into the space 8 below the hearth 6 and in a direction towards the aperture 9 and the chamber 10, after which the flue gases or equivalent are led up through the duct or ducts 11 and out through the flue 20. An air supply for the combus¬ tion is primarily admitted below the lower edge of the front hat¬ ches, which is shown by the arrow 75. The emission of the heated air is shown by the arrow 73. Without exceeding the scope of the concept of the invention modi¬ fications of the heating stove in accordance with the invention

should be possible. Hence it is not necessary that the heating stove be disposed for heating of air by air circulation through the heat¬ ing stove, whereby neither is it necessary to have a box-shaped flue duct. In such a heating stove the automatic filling of fuel may na- turally be utilised to advantage. The filling of fuel is in itself not necessary either in the case of a heating stove in accordance with the invention. Furthermore, the heating stove can display other component designs and dimensions and the fireplace and grate can, for example, be designed in a more customary manner. The embodiment has however illustrated a heating stove which can be disposed with the aforementioned items of equipement, which prove advantageous in specific cases. The said ducts 10, 11 can display a different shape which gives larger heat conduction areasor be provided with flanges for improved heat emission or give larger sweep areas for the cir- culation air.

The number of ducts can vary but they.should occupy a large area. There can be several front and other hatches and they can display other designs with suitable glass, grille etc. The heating-stove.can also be used as an open stove, i.e. with the front hatches open or dis- mounted. Here the automatic damper will be open and will be kept so by the spring, for which reason there is no risk of nuisance. A further and considerable advantage of the design which the heat¬ ing stove in accordance with the invention has obtained is that if use is not made of a fuel-filling duct or an equivalent duct, then there will be difficulties in lighting a heating stove of the kind in question as in the current manner it may have a resistance in the flue or a counterpressure, which however is dissolved or re¬ moved automatically in that the front hatches must be open when the heating stove is lighted, and closed as soon as possible there- after. Fuel filling can then take place through the filling hatch or naturally through opening of the front hatches. The procedure and the heating stove are thus not restricted to what has been described and illustrated in the embodiment but solely by the claims hereinafter.