DE9007823U1 - Stove, in particular stove, with a secondary air duct - Google Patents

Description

: KAW^SGHNECK

DIPL.-ING. DR. MANFRED RAU DIPL.-PHYS. DR. HERBERT SCHNECK AUTHORIZED REPRESENTATIVE AT THE EUROPEAN PATENT OFFICE

Karl-Stefan Riener

Müllerviertel 2o, A-4563 Micheldorf

Stove, especially a fireplace, with a secondary air duct

D-8500 NUREMBERG 1 KONIGSTRASSE 2 TELEPHONE 09 11 / 24537 FAX 09 11/20 8549 TELEX 623965 POST CHECK OFFICE NBG. 1843 52 -

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Stove, especially a fireplace, with a secondary air duct

The invention relates to a stove, in particular a fireplace stove, with a combustion chamber composed of several parts, with a front wall in which openings closed by combustion chamber doors are arranged for loading and/or cleaning the combustion chamber, with side walls and a rear wall and with the side walls and the rear wall, with the interposition of a convection chamber, cladding elements arranged in front of them.

There are already various stoves known that are designed differently to control the combustion process or have different draught control devices. Known stoves are equipped with inlet openings in the area of the grate or the firebox doors, the cross-section of which can be adjusted to suit different operating conditions of the heating device or heating equipment. With the so-called fireplace stoves of the more modern design, which consist of a sheet steel casing for the combustion chamber and a sheet steel casing in front of this for the convection casing and are equipped with large firebox doors with transparent panes, the problem has repeatedly arisen.

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It has been shown that the panes arranged in the combustion chamber doors have fogged up after a relatively short period of operation, or that soot particles and combustion residues have burned into the panes. For this reason, it has already been proposed for these stoves to provide an air supply in the area of the upper ends of the combustion chamber doors, so that the fresh air supplied, which is usually considerably colder than the combustion gases contained in the combustion chamber, can fall down over the inside of the panes of the combustion chamber doors as an air curtain. At the same time, the air supplied in this way could be used as secondary air for combustion. For example, it has already been proposed to provide a combined primary and secondary air control device in the area of the ash pane, whereby, depending on the position of the control device, part of the fresh air supplied is fed via distribution channels into the area above the combustion chamber doors, from where it falls downwards into the combustion chamber. Such supply air systems have proven themselves to be effective. However, an even distribution of the supply air, especially in stoves that have a polygonal cross-section when viewed from above and in which the combustion chamber doors are also bent, was not always ensured.

The present invention is therefore based on the object of creating a furnace in which a favorable combustion process and thus good economic efficiency can be achieved and in which, moreover, contamination of the panes arranged in the combustion chamber doors can be prevented.

This object of the invention is achieved in that in a flue gas duct, which extends from an inlet between a front edge of the loading and/or cleaning opening facing the cover plate of the combustion chamber and a dome-shaped attachment in the area of the ends of the firebricks facing the cover plate of the combustion chamber to the area of a flue gas outlet in the area of the cover plate, a secondary air duct is arranged between the front wall and the flue gas duct and is separated from the flue gas duct by an air baffle, wherein an outlet of the secondary air duct is through the cover plate of the

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The secondary air duct is formed by a stop bar closer to the combustion chamber and the air guide bar spaced away from it in the direction of the combustion chamber and is connected to the ambient air via openings arranged in the front wall or the front wall section. The advantage of this solution is that the arrangement of the secondary air duct in the area of the flue gas duct ensures a perfect supply of secondary air, which can be used to flush the panes in the combustion chamber doors and at the same time the arrangement of the secondary air duct means that the secondary air is heated accordingly as it falls down along the combustion chamber doors and already in the secondary air duct, so that the combustion process or the temperature in the combustion chamber is not adversely affected by the incoming secondary air.

According to another embodiment, it is provided that the secondary air duct is arranged on the side facing away from the air guide strip through the step-shaped profile that forms the stop strip and the rear wall or bottom wall plate for the warming or baking compartment, whereby a simple construction of the secondary air duct with few parts is achieved.

Furthermore, it is also possible for a secondary air control device to be assigned to the openings in the front wall or the stepped profile, whereby the secondary air can be controlled directly in the area of the inlet openings to the secondary air duct.

It is also advantageous if the secondary air duct is divided into a ventilation duct and an air guide duct, whereby the ventilation duct is connected to the outlet in the area of the panes of the combustion chamber doors running parallel to the front wall parts, while the air guide duct with secondary air outlets is arranged in the area of the side panes running parallel to the front wall side parts, since the separate supply of secondary air into the ventilation duct and into the air guide duct ensures an even distribution of the secondary air

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or the purge air across the entire width of the combustion chamber doors, especially even in the case of bent or polygonal combustion chamber doors.

It is also possible for the ventilation duct and the air duct to have independent openings for the supply air, whereby the amount of secondary air supply can be better controlled according to the operating conditions and the combustion conditions in the combustion chamber.

According to another variant, a common secondary air control device is assigned to the ventilation duct and the air duct, whereby few parts are required and operation can be simplified by a common actuating element.

However, it is also possible for the secondary air control device to comprise a slide plate that can be moved parallel to the support surface and is aligned parallel to the front wall, which is connected to an actuating arm that passes through the front wall and, if applicable, the stepped profile and is guided in an elongated hole in the front wall or part of the front wall, so that only a few, simply designed parts are required.

It is also advantageous if the secondary air control device has a web formed on the slide plate, extending in the direction of the air guide strip, which is arranged between the openings assigned to the ventilation duct or the air guide duct, since the division into the ventilation and air guide ducts can be carried out by the slide plate itself.

According to another embodiment, the air guide strip is mounted so that it can be adjusted vertically to the front wall via an adjustment device and can be moved from a rest position adjacent to the front wall or the stepped profile, closing the openings, into a

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opening position is adjustable in the direction of the rear wall, whereby the secondary air supplied to the combustion chamber can be regulated simultaneously by changing the cross-section of the secondary air duct.

However, it is also possible that the adjustment device is formed by threaded rods that are freely rotatably mounted in the front wall and are guided in an internal thread in a hole that passes through the air guide strip and are provided with a handle on the side facing away from the combustion chamber, whereby a sensitive adjustment of the secondary air supply can be achieved.

It is also advantageous if the dome-shaped attachment has a crown-shaped support frame, which is provided with a recess running roughly parallel to the cover plate and this has a guide frame in which a heat-resistant insulating plate, e.g. made of vermicolite, is inserted, as this prevents excessive radiation of heat energy in the direction of the flue gas outlet and, above all, keeps the heat in the combustion chamber area and in the area of the fuel during the combustion process, so that there is intensive gasification or outgassing of flammable vapors, which accelerate or keep the combustion process constant. By slowing down the heat dissipation, the combustion gas temperature in the combustion chamber can be increased quickly.

It is advantageous if the crown-shaped support frame is made of cast iron, as cast iron not only provides a robust design but also allows for appropriate heat storage in the areas adjacent to the insulation plate.

However, it is also possible that the recess in the frame area for the heat-resistant insulation plate is closed by a thin plate, in particular made of cast iron, whereby direct flame exposure to the heat-resistant insulation plate is avoided and a longer service life can be achieved.

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According to another embodiment, it is provided that the dome-shaped attachment or the ring-shaped support frame have a stop bar, which is assigned to the front sides of the combustion chamber lining, in particular the firebricks, assigned to the cover plate, and has a guide frame that protrudes in the direction of the base plate of the combustion chamber and rests against the front edges of the combustion chamber lining, in particular the firebricks, facing the combustion chamber, since this simultaneously enables the firebricks to be positioned in the combustion chamber and thus saves additional fastening devices.

Furthermore, it is also possible that a width of the ring-shaped support frame corresponds to a width between the side walls of the combustion chamber minus twice the wall thickness of the cladding elements, in particular the firebricks, whereby an exact and dense arrangement of the firebricks in the combustion chamber can be achieved.

An advantageous variant is one in which a primary air supply device is arranged in the area of an ash box below the combustion chamber. The device consists of a bracket attached to the side wall, which forms an acute angle with the side wall, and a sealing bracket with an approximately V-shaped profile inserted into this bracket, whereby the sealing bracket is connected in terms of movement to an actuating rod that passes through the front wall. By using a V-shaped profile, a self-centering and self-sealing sealing device is achieved, which reliably prevents unwanted inflow of primary air into the combustion chamber.

Furthermore, it is also possible that an opening angle between the legs of the retaining bracket that are adjacent to the side walls is smaller than an opening angle between the legs of the sealing bracket that are connected to the actuating rod, whereby the sealing bracket is always pressed under a corresponding pressure load in the direction of the side wall and thus a tight seal is guaranteed over a long period of time without readjustment.

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Finally, it is also possible for the leg associated with the side wall to have a greater length perpendicular to the adjustment direction than the leg of the sealing angle connected to the actuating rod, whereby a weight balance between the leg connected to the actuating lever and the leg associated with the side wall can be achieved in a simple manner.

For a better understanding of the invention, it is explained in more detail below using the embodiments shown in the drawings.

Show it:

Fig. 1 shows a furnace designed according to the invention in a simplified diagrammatic representation;

Fig. 2 the furnace according to Fig. 1 in side view, sectioned according to the lines II-II in Fig. 3;

Fig. 3 the furnace in plan view and in section, according to lines III-III in Fig.2;

Fig. 4 a part of the furnace in the area of the secondary air control device in side view, sectioned and on a larger scale;

Fig. 5 the furnace in the area of the secondary air control device in plan view, in section, along the lines V-V in Fig.4;

Fig. 6 shows the area of the furnace shown in Fig. 4 in front view;

Fig. 7 shows a furnace with another embodiment of a secondary air control device in side view, sectioned;

Fig. 8 shows a furnace in the area of the primary air control device in side view, partially sectioned;

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Fig. 9 shows a furnace in the area of the primary air control device in front view, sectioned along the lines IX-IX in Fig.8.

Fig. 10 shows a furnace with a primary and secondary air duct designed according to the invention in a diagrammatic representation, in section.

Fig.l shows a furnace 1 which has a combustion chamber 2 which is accessible via a loading and/or cleaning opening 3 which can be closed with combustion chamber doors 4,5. The loading and/or cleaning opening 3 is arranged in a front wall 6 of a one-piece component 9 which also forms side walls 7,8. The component 9 has a U- or C-shaped cross-section and mounting strips 10,11 running parallel to the front wall 6. The combustion chamber 2 is also closed off by a rear wall 12. A rear wall plate 13 of the convection jacket is attached to the mounting strips 10,11 at a distance from the rear wall 12. In the area of the side walls 7,8 the convection jacket is formed by cladding elements 14,15 and 16 which are arranged between stop strips 17 to 20. Above the combustion chamber 2 there is a warming or baking compartment 21 and below it there is a storage space 22, for example for fuel. Below the combustion chamber 2 in the storage space 22 there is also an ash box 23 with an ash drawer 24.

As can be seen better from Fig. 2, the rear wall 12 is connected in one piece with a base plate 25 and a cover plate 26, which form a one-piece component 27 that has a U-shaped cross section with unequal leg lengths. This is inserted between side cheeks 28, the legs that form the side walls 7, 8 of the one-piece component 9 that has the front wall 6 and is connected to the side cheeks 28 via schematically indicated weld seams 29. Of course, these weld seams 29, which are only partially shown for the sake of clarity, are continuous and must be sealed in order to prevent smoke gases from escaping from the combustion chamber 2.

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However, it is also advantageous that the side walls 28 protrude in the area of the weld seams 29 and therefore fillet welds can be produced instead of butt welds.

In the base plate 25, a grate 30 is also provided, which can be formed, for example, by a rotating grate, which can be operated via an operating rod 31 from outside the furnace body or from the front wall 6. It can also be seen from this illustration that the rear wall plate 13 is attached to the mounting strips 10 or 11.

The warming or baking compartment 21 is lined with ceramic plates 32 and is closed off from the combustion chamber 2 by a stepped profile 33. This profile 33 forms a rear wall panel and a base wall panel 35 of the warming or baking compartment 21. The base wall panel 35 is connected to a Profi Heil 36 running parallel to the front wall 6 and a stop strip 37 running perpendicular to the front wall 6 for the combustion chamber door 5.

In the area of a front edge 38 of the front wall 6, a further stop bar 39 is arranged for the combustion chamber doors 4, 5. The stop bar 39 forms one leg of a profile which is provided with a web 40 running parallel to the front wall 6 and a leg 41 extending in the direction of the combustion chamber 2. Due to the height offset of the leg 41 compared to the stop bar and the arrangement of the base plate 25 of the combustion chamber 2 below the front edge 38 of the front wall 6, both an ash 42 and a combustible material, such as logs, which is also indicated schematically and rests on this ash 42 or an ash stick, are located lower than the stop bar 39 and thus below the lower edge of the combustion chamber doors 4, 5. This prevents embers 43 or ash 42 from falling out when the combustion chamber door 4 or 5 is opened or when the stove 1 is operated with the combustion chamber doors 4,5 open.

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The closure of the combustion chamber 2 between the bent base plate 25, which rises towards the combustion chamber doors 4,5, and the stop bar, is provided by the front wall 6. A profile 44 is also provided, which forms the ash box 23 and is welded to the base plate 25. Firebricks 45 are arranged in front of the rear wall 12 and the side walls 7,8. The grate 30, which is designed as a rotating grate, is arranged in a grate plate 46 and this forms the lower closure of the combustion chamber 2. The firebricks 45 are guided between the grate plate 46 and the rear wall 12 or the side walls 7,8. The grate plate 46 is dimensioned in such a way that a gap corresponding to the wall thickness 47 of the firebricks 45 remains between the side walls 7,8 and the rear wall 12. Furthermore, a firebrick 45 is arranged between the grate plate 46 and the leg 41 of the profile forming the stop bar 39. The removable ash pan 24 is arranged below the grate 30 within the ash box 23. The firebrick 45 is fixed in its position relative to the rear wall 12 or the side walls 7, 8 in its upper end area facing the cover plate 26 by a dome-shaped attachment 48. For this purpose, the dome-shaped attachment 48 has a crown-shaped support frame 49, which can be made of cast iron, for example. This crown-shaped support frame 49 is provided with stop bars 50 and a guide frame 51. The front edges and inner sides 53 of the firebrick 45 are supported on the stop bars 50. In the upper end area of the dome-shaped attachment 48 facing the cover plate 26, a heat-resistant insulating plate is inserted in the upper part of the guide frame 51 surrounding a recess 54. The use of such a heat-resistant insulating plate 55 as the upper cover of the combustion chamber 2 means that the heat generated by the flames in the combustion chamber 2 cannot be immediately released to the smoke gases 56 that pass above the dome-shaped attachment 48 and are indicated schematically by arrows, and thus the heat can be concentrated in the combustion chamber 2, particularly during the combustion process, so that the existing fuel is heated more quickly and thus more combustible gases can be released from the fuel, thus causing combustion and greater heat development to occur more quickly.

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In Fig.2, a secondary air supply to the combustion chamber 2 is also shown. This is arranged above the combustion chamber doors 4, 5 and consists of a ventilation duct 57 and an air guide duct 58. The ventilation duct 57 and the air guide duct 58 are arranged in a flue gas duct 59, which has an inlet that is limited by the dome-shaped attachment 48 and the stop bar 37. The flue gas duct 59 opens into a flue gas outlet 60, which is arranged in the area of the cover plate 26 of the combustion chamber 2. The ventilation duct 57 and the air guide duct 58 are separated from the flue gas duct 59 by a step-shaped profile 61. In a secondary air duct 62 separated from the flue gas duct 59 by the profile 61, the ventilation duct 57 is separated from the air guide duct 58 by a web 64 connected to a slide plate 63. The secondary air indicated by arrows 65 is supplied via openings 66 in the profile part 36 of the profile forming the stop bar 37 and in the front wall 6. The openings 66 can be completely closed or completely opened by the slide plate 63 connected to a handle 67, which can be moved perpendicularly to the side walls 7, 8. The secondary air entering the ventilation duct 57 through the openings 66 and symbolically indicated by arrows 65 is colder and therefore heavier than the hot air present in the combustion chamber 2. It therefore falls downwards, guided by the profile 61 and the stop bar 37, and exits in the upper area of the firebox doors 4,5 near the panes 68 inserted in these firebox doors. It falls downwards along these panes 68 until it hits the stop bar 39, from which it is passed on via the leg 41 in the direction of the grate 30, where it is available for burning the fuel.

As the secondary air passes along the profile 61, which is arranged in the flue gas duct 59 and is heated up to a high degree by the hot flue gases, the secondary air is also constantly heated on its way into the combustion chamber 2 or to the fuel, but until the combustion process begins it still has a lower temperature than the fuel gases present in the combustion chamber 2. On the other hand, however, the constant heating of the supplied air prevents

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the fuel materials or fuel gases in the combustion chamber 2 cool down too much and the combustion process of the fuel materials is therefore promoted by this type of secondary air supplied. At the same time, the freshly supplied secondary air flows along the panes 68 - as shown by arrows 65 - so that no smoke gases can adhere to them and thus contamination or soot components burning into the panes 68 is prevented.

The secondary air supplied via the air duct 58 is supplied to the panes in the side areas of the combustion chamber doors 4,5, as will be explained in more detail in the following illustrations.

Fig.3 shows the stop strip 19 for the cladding elements 15, which are formed by one-piece tiles 69. These stop strips 17 to 20 are held at a distance 71 from the side walls 7, 8 of the stove 1 via support webs 70. This distance 71 is greater than a distance 72 between the stop strip 19 and a guide surface 73. This difference between the distance 71 and the distance 72 between the stop strip 19 and the side wall 7 now makes it possible to bring a tile 69 exactly to the stop strip 19 and to position it exactly in the front area near the firebox doors 4 or 5. In the area adjacent to the guide surface 73, the dimensional accuracy of the tile 69 no longer has to be so great and it is still possible for the tile 69 to be placed exactly on the stop strip 19 and a good overall visual impression is achieved. For this purpose, the tile 69 or the cladding element 15 is pressed by means of a holding device 74, which in the present embodiment is formed by spring arms 75 released from the rear wall plate 13, with forces directed in the direction of an arrow 76 and 77 in the direction of the stop bar 19 or in the direction of the front wall 6 of the oven 1. This ensures that the tile 69 is fixed between the guide surface 73 and the stop bar 19, in which the thickness of the cladding element 15 or the tile 69 is exactly adapted to the distance 72, and at the same time in that

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Area in which the thickness of the cladding elements 15 or tiles 69 can be less than the distance 71, these are pressed against the stop bar 19 without play.

Furthermore, it can be seen from this illustration that the rear wall panel 13 is attached to the mounting strips 10, 11, which are molded onto the component 9 forming the side walls 7, 8, via fastening means 78, for example screw-nut arrangements, and as a result, when the rear wall panel 13 is mounted, the forces directed in the direction of the arrows 76 and 77 are automatically exerted on the cladding elements 15 or the tiles 69 via the holding device 74. After dismantling the rear wall panel 13, it is then easy to pull the cladding elements 15 or the tiles 69 out of the holders formed by the support webs 70 and the stop strips 19 in the opposite direction to the arrow 77. This makes it easy to mount and replace these cladding elements 15 at any time, both for cleaning and in the event of damage. However, instead of the notched spring arms 75, the holding device 74 can also be provided with a multiply beveled edge strip which projects over the rear wall panel 13 in the direction of the cladding elements 15 and thereby exerts a contact force directed in the direction of the cladding elements 15 or the stop strips 19 when the rear wall panel 13 is mounted.

At the same time, these cladding elements 15 have recesses 79, which form a convection space through which the ambient air can pass between the side walls 7, 8 in contact with the combustion chamber 2 and the surfaces of the cladding elements 15 facing away from the stop strips 19. These recesses 79 form continuous channels in the vertical direction of the furnace 1, since the support webs 70 are not arranged continuously over the entire length of the stop strips 19. Instead, they consist of several strips that are arranged at a distance from one another over the length of the side wall or are provided with recesses corresponding to the recesses 79. The air flowing through the recesses 79, which passes through corresponding openings 80 in a cover 81 placed on the furnace 1 -

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Fig.l - can escape into the open air, excessive heating of the cladding elements 15 is prevented. Furthermore, these cladding elements 15 provide protection against contact, which prevents burns if a person accidentally touches the oven.

Furthermore, it can be seen from this illustration in Fig.3 that a width 82 between the guide frame 51 of the dome-shaped attachment 48 is smaller by twice the wall thickness 47 of the firebricks 45 than a distance measured perpendicularly to the side walls 7, 8 between the facing surfaces of the side walls 7 or 8. As a result, the firebricks 45 are positioned and held in place between the stop strips 50, the guide frame 51 and the side walls 7 and 8 or the rear wall 12. As can also be seen from this illustration, the web 64 of a secondary air control device 83 extends essentially over a width that essentially corresponds to a width of a front wall part 84 that runs parallel to the rear wall 12. As a result, the secondary air supplied via openings 66 can only flow or fall downwards between the profile 61 and the side panes 86 of the combustion chamber doors 4,5 in the area of the front wall side parts 85, which run at an angle between the front wall part 84 and the side walls 7 and 8. This ensures that the side panes 86 of the combustion chamber doors 4,5 in the area of the front wall side parts 85 are also flushed with fresh secondary air, so that no soot deposits or burn-in spots can occur on them either.

Furthermore, it can be seen from this illustration that in the area of the loading and/or cleaning opening 3, the side walls 7, 8 have tabs 87 that protrude beyond the stop strips 17 to 20 and extend approximately perpendicularly to the rear wall 12. Bearing devices 88, for example hinge bands 89, for holding the combustion chamber doors 4, 5 are mounted on these tabs 87.

End faces 90 of these tabs 87 serve as stop strips for the combustion chamber doors 4,5. As can also be seen from this illustration, these end faces 90 are supported by a circumferential groove 91 in a frame

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92 of the combustion chamber doors 4,5, so that there is an exact seal between the tabs 87 and the combustion chamber doors 4,5. Likewise, one of the two combustion chamber doors 4,5, in this case the combustion chamber door 4, has a stop strip 93 on the side facing the combustion chamber door 5, which, when closed, engages in a groove 94 of the other combustion chamber door 5 from the side of the combustion chamber 2. This also provides sufficient sealing against the ambient air in the joint area of the combustion chamber door 4,5.

From the top view of the base plate 25 it can also be seen that firebricks 45 can also be arranged between the grate plate 46 and the firebricks 45 facing the side walls 7, 8. It is of course also possible for the grate plate 46 to be so large that it covers the entire floor. By arranging openings 95, 96 in the rotating grate 30 and the grate plate 46, the openings 95 and 96 can be closed by adjusting the rotating grate 30 relative to the grate plate 46, so that air supply from below through the grate can also be switched off. The rotating grate 30 can be operated using the operating rod 31 - as shown in Fig. 2.

In Fig.4, the secondary air control device 83 is shown on a larger scale above the combustion chamber doors 4, 5. It can be seen that the openings 66 pass through both a front wall 6 in the area of a front wall part 84 of a stop bar 18 and a Profi Heil 36 connected to the stop bar 37. On the side of the Profi Heil 36 facing away from the front wall part 84, a web 64, which can be formed by a hat profile, for example, is arranged.

As can be seen better from Fig.5 and Fig.6, the handle 67, which is connected to the web 64 in terms of movement, is adjustable in an elongated hole 97. For this purpose, a threaded rod 98, which is connected to the handle in terms of rotation, is screwed into an internal thread 99 of the web 64. By rotating the handle 67 about an axis 100, the distance between the web 64 and a projection 101 of the handle 67 can be increased and the web 64 can thus be loosened.

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In this state, the web 64 can be moved together with the handle 67 along the elongated hole 97 into different positions. This allows an opening width 102 between the opening 66 arranged in the front wall part 84 and the opening 103 arranged in the web 64 to be changed. If the two openings 66 and 103 are in a covering position, this corresponds to a maximum opening width 104 of the openings 103 and 66. By screwing in the handle 67, the web 64 can be pressed against the projection 101 and fixed in its respective position. As can best be seen from Fig.4, the web 64 has a height 105 in the vertical direction of the oven, so that the openings 66 arranged one above the other in the vertical direction can be opened and closed simultaneously.

It is of course also possible to divide the web 64 or the profile forming the web and to provide each with its own handle 67 so that the air supply to the panes 68 in the area of the front wall part 84 and the side panes 86 in the area of the front wall side parts 85 can be regulated independently of one another.

From the top view in Fig.5 it can be seen that the secondary air or fresh air supplied via the openings 66 and shown schematically by arrows 65 is distributed across the air duct 58, i.e. between the two side walls 7 and 8, whereby this air duct has outlets 106 in the transition area between the panes 68 and the side panes 86, from which the secondary air emerges according to the arrows 65 and is distributed over the entire surface of the side panes 86 and, as indicated in Fig.6, can sink downwards towards the base plate of the combustion chamber. During the distribution of the secondary air in the air duct 58, the secondary air is heated by the hot flue gases in the flue gas duct 59 which pass along the side facing away from the secondary air control device 83. As it falls down along the discs 68 or the side discs 86, it is heated even further, so that when it reaches the area of the fuel or the base plate or the embers, the fuel no longer cools down significantly.

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Completely independent of this distribution of the secondary air via the air guide channel 58, the secondary air supplied via the openings can fall downwards through the ventilation channel 57 according to the arrows 65 directly over the panes 68 on the side of the combustion chamber doors 4, 5 facing the combustion chamber, thus preventing the panes 68 from fogging up or smoke or soot residues from burning in. Due to the slanted course of the profile 61 in the form of an air guide strip 107, the secondary air falling downwards is directed according to the arrows 65 directly onto the inside of the panes 68 facing the combustion chamber 2, so that they are sufficiently flushed with fresh air.

From Fig.4 it is also clear that the stop bar 37 engages in the groove 91 of the frame 92 of the combustion chamber doors 5 and thus a clear seal of the combustion chamber 2 against the ambient air is achieved in the area of the stop bar 37.

Fig.7 shows another embodiment variant in which the design of the furnace 1 corresponds approximately to that of Fig.4, which is why the same reference numerals are used for the same parts.

In this case, the profile 61 with the air guide strip 107 is mounted on a threaded rod 108, which is connected to the handle 67 in a rotationally fixed manner. The handle 67 is freely rotatable by the extension 101 and an abutment disk 109, but is immobilely mounted perpendicular to the front wall 6. By turning the handle 67 in one of the two directions indicated by a double arrow 110, the profile 61 can now be adjusted from the position shown in dashed lines, resting on the stop bar 37 or the profile part 36, in which the inflow of secondary air through the openings 66 is prevented, to the position shown in solid lines, so that, depending on the distance that the profile 61 takes up from the front wall 6, secondary air indicated by arrows 65 can penetrate into the area of the combustion chamber doors 4, 5.

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Of course, in order to ensure a tight seal between the profile 61 and the profile part 36, it is also possible to provide several such handles 67 over the width of the profile 61 extending perpendicular to the side walls 7,8.

In Fig.8 and 9, a primary air supply device 111 is shown, which can be arranged in the area of an ash box 23 to the side next to the ash pan 24. This primary air supply device 111 consists of a bracket 112 fastened to a side wall 7 or 8, which has a widening V-shaped design with an opening angle 113 in the direction of a cover plate 26 of the oven 1. A sealing angle 114 is inserted into this bracket 112 from the open side of the bracket 112, which has a larger opening angle 115 than the opening angle 113 of the bracket 112. The bracket 112 can be fastened to the side wall 7, for example by a weld seam 29 or by any other connection, for example rivets or screws.

The sealing angle 114 in turn has a longer leg 116 and a shorter leg 117, wherein the shorter leg 117 is connected to an actuating rod 118 of an adjusting member 119.

Because the opening angle 115 is larger than the opening angle 113, the sealing angle 114 is always pressed against the side wall 7 and lies sealingly against the retaining angle 112.

As can be seen better from Fig.9, openings 66 are arranged in the side wall 7, which also pass through the bracket 12. In the sealing bracket 114, in the position shown in Fig.9, openings 120 are arranged offset from the openings 66. By adjusting the sealing bracket 114 in the direction of a double arrow 121, the openings 66 and 120 can be brought into a more or less overlapping position, whereby the amount of primary air fed through the openings 66 into the ash box and from there to the grate 30 can be easily regulated.

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Due to the greater length of the leg 116 compared to the leg 117, an automatic symmetrical position of the sealing angle 114 can be achieved, since the greater weight, caused by the actuating rod 118, can be compensated by the larger size of the leg 116. This prevents the sealing angle 114 from tipping over in the direction away from the side wall 7 and thus a failure of the primary air control device.

In Fig. 10, a furnace designed according to the invention is shown in a half-section in a diagrammatic representation in order to better illustrate the air flow in the area of the supply air and the exhaust air. In order to facilitate overall understanding, the parts that are omitted due to the half-section are shown in a kind of phantom representation in the form of outlines in dashed lines.

As can now be seen from this illustration in Fig. 10, a secondary air 122, which is indicated by dashed arrows, enters through the openings 66 into the air guide channel 58, from where it is supplied to the combustion chamber 2 distributed over the entire surface of the side windows 86. A secondary air 123 - also indicated by dashed arrows - also enters through openings 66 into a secondary air channel 62 located below the air guide channel 58, from where it falls down into the combustion chamber 2 via the ventilation channel 57 along the windows 68 of the combustion chamber doors 4, 5. A primary air 124 also enters the combustion chamber 2 from below through openings 66 on the side wall, which is only shown in phantom form, via the primary air supply opening 111 through openings 95 in the grate 30. The flue gases 56 produced during combustion then pass the dome-shaped attachment 48 between the heat-resistant insulation plate 55 and the base wall plate 35 to a flue gas outlet 60 in the cover plate 26, which closes off the combustion chamber 2 at the top. In order to prevent the hot flue gases 56 from passing too quickly through the flue gas channel 59, a flue gas deflection plate 125 can be arranged, as shown in Figs. 2 and 3 by dashed or dash-two-dotted lines. The flue gas deflection plate 125 points away from the side walls 7, 8 of the combustion chamber 2 and from the rear.

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wall plate 34 has a minimum distance of 4 cm, as prescribed by the corresponding standards in the various countries, in particular the Federal Republic of Germany. This reduces the cross-section of the flue gases 56 and at the same time lengthens the path that the flue gases have to travel, so that more intensive heat can be released to the surrounding sheet metal walls. It is particularly advantageous here if the flue gas deflection plate 125 is designed as a highly heat-resistant insulating plate, so that the radiation losses in the direction of the flue gas outlet 60 are as low as possible and the flue gases release their heat energy as far as possible to the surrounding sheet metal walls of the furnace.

To hold this flue gas deflection plate 125, a holding strip 126 is arranged on the rear wall 12 of the combustion chamber 2, on which it rests and is supported at its end facing away from the rear wall 12 on spacer blocks 127, which ensure that a corresponding minimum cross-section is maintained between the rear wall plate 34 and this flue gas deflection plate 125.

Furthermore, it is also advantageous if the dome-shaped attachment 48 - as indicated in Fig. 2 between the attachment 48 and the profile 61 with dashed lines - is equipped with sloping surfaces in its end areas facing the two side walls 7 and 8. This can improve the flue gas flow in the combustion chamber 2 and prevent the heat energy from being radiated too quickly to the flue gases 56 passing by in the flue gas channel 59.

Of course, it is also possible to use any other material, such as a sheet metal plate or a cast part, instead of the heat-resistant insulation plate for the flue gas deflection plate 125.

Claims (18)

-1- Protection claims 1. Stove, in particular a fireplace stove, with a combustion chamber composed of several parts, with a front wall in which openings closed by combustion chamber doors are arranged for loading and/or cleaning the combustion chamber, with side walls and a rear wall and with the side walls and the rear wall, with the interposition of a convection chamber, cladding elements arranged in front, characterized in that in a flue gas channel (59) which extends from an inlet between a front edge of the loading and/or cleaning opening (3) facing the cover plate (26) of the combustion chamber (2) and a dome-shaped attachment (48) in the area of the ends of the firebricks (45) facing the cover plate (26) of the combustion chamber (2) to the area of a flue gas outlet (60) in the area of the cover plate (26), a secondary air channel (62) between the front wall (6) and the flue gas channel (59) and is separated from the flue gas duct (59) by an air baffle, an outlet of the secondary air duct (62) being formed by the stop strip (37) closer to the cover plate (26) of the combustion chamber (2) and the air baffle (107) spaced away from it in the direction of the combustion chamber (2) and which is connected to the ambient air via openings (66) arranged in the front wall (6) or the front wall part. 2. Oven according to claim 1, characterized in that the secondary air channel (62) is arranged on the side facing away from the air guide strip (107) through the stepped profile forming the stop strip (37) and the rear wall or bottom wall plate (34,35) for the warming or baking compartment (21). -2- 3. Oven according to claim 1 or 2, characterized in that a secondary air control device (83) is associated with the openings (66) in the front wall (6) or the stepped profile (61). 4. Oven according to one or more of claims 1 to 3, characterized in that the secondary air duct (62) is divided into a ventilation duct (57) and an air guide duct (58), the ventilation duct (57) being connected to the outlet in the region of the panes (68) of the combustion chamber doors (4, 5) running parallel to the front wall parts (84), while the air guide duct (58) is arranged with secondary air outlets in the region of the side panes (86) running parallel to the front wall side parts (85). 5. Oven according to one or more of claims 1 to 4, characterized in that the ventilation channel (57) and the air guide channel (58) are assigned independent openings (66) for the supply air. 6. Oven according to one or more of claims 1 to 5, characterized in that a common secondary air control device (83) is assigned to the ventilation channel (57) and the air guide channel (58). 7. Oven according to one or more of claims 1 to 6, characterized in that the secondary air control device (83) comprises a slide plate (63) which is displaceable parallel to the support surface and aligned parallel to the front wall (6), which is connected to an actuating arm which passes through the front wall (6) and optionally the step-shaped profile (61) and which is guided in an elongated hole (97) in the front wall (6) or the front wall part (84). 8. Oven according to one or more of claims 1 to 7, characterized in that the secondary air control device (83) has a web (64) formed on the slide plate (63), extending in the direction of the air guide strip (107) and arranged between the openings (66) associated with the ventilation channel (57) or the air guide channel (58). -3- 9. Oven according to one or more of claims 1 to 8, characterized in that the air guide strip (107) is mounted so as to be adjustable perpendicular to the front wall (6) via an adjusting device and can be adjusted from a rest position resting on the front wall (6) or the step-shaped profile and closing the openings (66) into an open position spaced away in the direction of the rear wall (12). 10. Oven according to one or more of claims 1 to 9, characterized in that the adjusting device is formed by threaded rods (108) which are freely rotatably mounted in the front wall (6) and are guided in an internal thread in a bore which passes through the air guide strip (107) and are provided with a handle (67) on the side facing away from the combustion chamber (2). 11. Oven according to one or more of claims 1 to 10, characterized in that the dome-shaped attachment (48) has a ring-shaped support frame (49) which is provided with a recess (54) running approximately parallel to the cover plate (26) and this has a guide frame (51) in which a heat-resistant insulating plate (55), e.g. made of vermicolite, is inserted. 12. Oven according to one or more of claims 1 to 11, characterized in that the ring-shaped support frame (49) consists of cast iron. 13. Oven according to one or more of claims 1 to 12, characterized in that the recess (54) in the receiving frame area for the heat-resistant insulating plate (55) is closed by a thin plate, in particular made of cast iron. 14. Furnace according to one or more of claims 1 to 13, characterized in that the dome-shaped attachment (48) or the ring-shaped support frame (49) have a stop bar (50) which is assigned to the end faces of the combustion chamber lining assigned to the cover plate (26), in particular the firebricks (45), and has a stop bar (50) extending in the direction of the -4- Base plate (25) of the combustion chamber (2) has a guide frame (51) projecting, which rests on the front edges (52) of the combustion chamber lining facing the combustion chamber (2), in particular the firebricks (45). 15. Oven according to one or more of claims 1 to 14, characterized in that a width (82) of the ring-shaped support frame (49) corresponds to a width between the side walls (7, 8) of the combustion chamber (2) minus twice the wall thickness (47) of the cladding elements, in particular the firebricks (45). 16. Oven according to one or more of claims 1 to 15, characterized in that a primary air supply device (111) is arranged in the area of an ash pan (23) below the combustion chamber (2), which consists of a holding bracket (112) fastened to the side wall (7, 8) and enclosing an acute angle with the side wall (7, 8) and a sealing bracket (114) with an approximately V-shaped profile inserted in this holding bracket (112), the sealing bracket (114) being connected in terms of movement to an actuating rod (118) passing through the front wall. 17. Oven according to one or more of claims 1 to 16, characterized in that an opening angle (113) between legs (116, 117) of the holding angle resting on side walls (7, 8) is smaller than an opening angle (115) between the legs of the sealing angle (114) connected to the actuating rod (118). 18. Oven according to one or more of claims 1 to 17, characterized in that the leg associated with the side wall (7, 8) has a greater length perpendicular to the adjustment direction than the leg of the sealing angle (114) connected to the actuating rod (118).