EP3019792B1 - Combustion furnace having a lifting mechanism for conveying the fuel - Google Patents

Description

Technical area

The invention relates to a combustion furnace for solid fuel, in particular a wood-burning stove, with a combustion chamber, which is associated with a storage space for supplying and refueling, wherein the combustion furnace has a height-adjustable grate in a substantially non-ventilated shaft, wherein below the combustion chamber Unvented shaft as a storage space for the fuel and in which the grate is provided as a platform for the fuel supply for supplying and refueling of fuel from the storage room into the firebox.

State of the art

Fireplaces with removable grids, which can be inserted at different heights, are known to adapt to different fuels as well as to the distance setting about to a water jacket for central heating. A mechanical height adjustment of a charcoal grate by means of a crank mechanism, the US 5996572 A be removed. It sets the distance between embers and grilled food and thereby dictates the effective grill temperature. It is essential, according to the US version, that the space under the grate for the charcoal is ventilated. To accelerate the air circulation below and above the embers, a fan is arranged on the side. If you want to cook by means of hot air, then a hood is slipped over the grill. The fuel, in this case charcoal, is ignited in its entirety and converted to glow. A new addition of charcoal is not provided.

The US 20060096585 A also relates to a grill with a stationary arranged charcoal bowl. By means of a kinematic scissors and with an electromotive spindle drive the grill grate is changed in the distance to the charcoal grill. Temperature sensors measure the effective grill temperature and raise or lower the grill to keep a desired grill temperature constant.

From the GB 972341 A is a coal furnace with arranged above the firebox storage space for coal known. The grate, which limits the firebox down, can be lowered to accommodate the ash or slag and eventually tilted for emptying. About the height adjustment, the power can also be controlled. The furnace is thus fed from above with fresh coal in the manner of a continuous fire, with heat exchangers for hot water preparation (central heating) being provided in the parting plane between the storage space and the combustion chamber. The coal sinks slowly from the storage room to the firebox where it is burned and the fire or embers can be maintained long in the area of action of the heat exchanger because the increasingly accumulating ash and slag are lowered down the grate and finally discharged ,

The CH 281678 A relates to a furnace with adjustable grate, with the aim of adjusting the heat output by raising or lowering the fire and the embers in the fire shaft to the needs. A storage room for fuel is not provided. This also applies to the oven after the CN 2086372 U , It is a cooker with an attachable saucepan and a lowered against the force of a spring rust. The coal ignited on the grate becomes ash and slag after ignition and thus lighter. The decreasing heat output that goes hand in hand with this is compensated by raising the remaining embers, so that the heat output of the amount of coal used (in this case 0.5 kg) can be kept approximately the same until extinguished. Alternatively to the spring mounting of the grate, a lever system for adjusting the grate can also be used. This makes it possible to keep the heat output constant by lifting, but also by lowering to reduce, for example, to prevent overcooking during the cooking process.

The FR 445970 A relates to an oven that can be used both as a stove, as well as a hotplate. For this purpose, the hearth, which consists of a fire bowl with a ground formed as a grate, in the interior of the furnace in height adjustable. If the fire bowl is inside one cylindrical shell of heat-storing material at the bottom, then it is heated in the first place. When cranking up the firebox in the internal thread of the furnace liner, place the firebox immediately under the furnace plate, which forms the cooking plate for heating pans or pots. The entire cylindrical interior of the furnace is ventilated from below. A refueling into the fire bowl takes place from above after removing the hotplate.
The DE 3538511 A1 relates to underfeed firing with a horizontal auger which forces the fuel from a separate silo through a vertical fuel supply duct into a fire pit. The bottom of the fire bowl is formed by a perforated annular disc which surrounds the fuel feed channel like a collar. The fuel supply passage is telescopically inserted and deployed, thus positioning the washer within the fire pit. By varying the position, depending on the shape and composition of the fuel, it is possible to achieve an always constant mushroom-shaped surface of the fuel in the fire pit. Depending on the fuel quality, the setting for optimization should be made anew. This document also discloses the preamble of claim 1. The US Pat. No. 2,624,329 relates to a combi stove with a hotplate, a grate that carries the entire fuel charge and can be adjusted by a lifting spindle or scissors (possibly with electric drive) for temperature adjustment up and down at a distance from the hotplate. A cage of vertical bars surrounds the grate and serves for air circulation, as well as the anti-rotation of the grate in vertical positioning. The outgoing heat can be used for heating domestic hot water or for space heating.

Presentation of the invention

The invention aims to keep a log fire, without refueling by hand, to keep going for several hours.

This is achieved in a combustion furnace according to the invention of the type described above, characterized in that in the region of the confluence of the non-ventilated shaft in the combustion chamber surrounding a junction nozzle ring is provided for air supply into an annular space of a first combustion zone. The provided for refueling fuel, such as logs, are thus placed on the platform located in the uppermost position prior to commissioning of the stove, this gradually lowered while stacking more logs until the platform in the unventilated shaft drove all the way down and the shaft is completely filled. The logs lying in the focal plane with the lateral air supply are ignited. They burn there - and only there - as a result of the air supply, while the logs piled thereunder do not burn because of lack of ventilation, but form the long-term supply. It can be provided one above the other several combustion zones. Thus, it is expedient if a further nozzle ring is provided for air supply at a distance above the first nozzle ring which ignites flammable gases from the first combustion zone in a second combustion zone in the combustion chamber, wherein the second nozzle ring is in an annular space with preferably smaller diameter than that the annular space of the first nozzle ring and the annular space forms the mouthpiece of a burner. The firebox with an openable window is located above the or the nozzle rings for the supply of combustion air.

In a simple preferred embodiment, the elevator via a crank, a cable or by means of a lever can be activated. If one recognizes that it would be useful as a result of the progressive burn-up in the focal plane and a decreasing flame height in the firebox to refill wood, then the elevator is operated by hand. The platform carrying the logs is e.g. lifted slightly by means of the crank and a spindle drive, a gear rack or a kinematic scissors so that new logs get into the focal plane with the lateral air supply nozzles. In a stove of the usual size for a living room can be maintained in this way a fire for six hours or more. Such a stove can be equipped with a water jacket and form the heat source for central heating.

An automatic heating results from the fact that the elevator has a motor drive, which is controllable in dependence on the combustion, for example by the exhaust gas temperature as a reference variable in terms of refilling, in particular the lifting speed of the fuel. If the exhaust gas temperature drops below an adjustable limit value, then the electromotive drive for the elevator, for example, is briefly switched on, so that new fuel is lifted into the focal plane. Thereby, a continuous burning process can be maintained. A arranged approximately in a living room stove with visible flame, which works as a burner for central heating, can be operated even in the absence of many hours.
Another preferred embodiment, which does not require any external energy supply, such as electricity, is characterized in that the elevator has a spring store with a spiral spring, which can be tensioned and / or recharged by means of a crank or the like while the grate is lowered, and that one Gear with a Hubspindel- or rack and pinion for the rust a regulator for the hub eg a wind vane controller as an aerodynamic escapement or one with a controlled by the exhaust gas temperature brake, for example, eddy current brake with variable braking power is switched on. By loading with fuel such as wood and the multiple cranking down of the grate, the coil spring is tensioned at the same time. The torque of the coil spring is released slowly via a gear with activated escapement or brake similar to a clockwork. The braking power can be changed as needed by means of the controller. As a result, the necessary lifting force can be applied for a continuous stroke of eg 50 cm over 6 hours.

An optimization of the combustion process results in a preferred manner in that a temperature sensor of the exhaust gas temperature via an actuator, a cam or a cam slide shifts or linearly displaced having at least one, preferably a plurality of cams, which lever act as a sensor, wherein a lever carries permanent magnets , the temperature-dependent more or less pivotable or slidable over a disc of the eddy current brake, wherein a second lever is kinematically connected to a flue damper for temperature-dependent opening or closing and a third lever flaps such as primary air flaps and secondary air flaps of the lateral air supply into the focal plane or the Firebox controls with regard to the opening angle. In this way, the stroke speed (ie the refueling of fuel), the fresh air volumes in the focal plane and the deduction cross section can be adjusted so that a burn is achieved permanently and with particularly good efficiency.

According to a preferred embodiment, it is expedient for both simple manual and complex control systems if at least one mechanical stop is provided directly above the focal plane, which limits the stroke of the elevator when it contacts the ignited fuel and its position the level of air supply is preset. The fuel abuts the stop and prevents unnecessary further rotation of the crank or lifting the grate and limits the amount of fuel supplied to the required level. Also with a motor drive ends the hub in any case, if the fuel, so here for example logs, pending the stop. Only when a certain layer has burned off, a hub can be made again.

In order to allow a filling after complete burning out of the continuously or intermittently pushed material without hindrance, it is expedient according to a preferred embodiment, when the stop is wegschwenkbar from the combustion zone, preferably a pivot lock on an oven door, the pan unlocks when the door is open.

In the subject invention, a distinction is made between the reservoir with still unused fuel and the combustion zone with the combustion chamber, which contains the burning fuel or the embers. This separation results from the targeted air supply, which is limited to the combustion chamber.

The incinerator is particularly suitable for all wood fuels, such as wood briquettes. For this purpose, it is expedient according to a preferred embodiment, when the storage space is formed as a circular cylindrical, tubular shaft for receiving preferably circular cylindrical wood briquettes. The then plate-shaped grate, which actually represents the platform for the still unused fuel supply to be supplied, is increased inside the tube depending on the combustion or constant or simply by manual operation in the tube, which is substantially unaerated. This burner is similar to a candle in a candlestick, which is raised with increasing burn, so that the flame is always burning at the same height substantially. In order to easily dissipate the ashes incurred in wood fuel ash and to ensure a symmetrical burn even at a furnace with possibly one-sided open firebox, it is also useful if the grid as a platform for supporting and Nachschieben the fuel supply rotatable about a vertical axis in the shaft is arranged and over one Rotary drive in addition to the elevator has. The ash can then easily trickle down in the gap between the lateral surface of the wood briquettes and the inner pipe wall and is caught there in an ash tray. The rotation of the fuel supply also counteracts jamming in the stroke movement in the interior of the tube. As a result of the uniform burning on the surface, the efficiency increases. The heat is released evenly throughout the firebox.

Brief description of the drawings

• Fig. 1 zeigt eine Schrägansicht eines Kaminofens von vorne, teilweise im Schnitt,
• Fig. 2 eine Schrägansicht des Kaminofens von der Seite mit einem temperaturgesteuerten Hebewerk,
• Fig. 3 einen Querschnitt durch einen Kaminofen für Holzbriketts mit drehendem Rost in einem rohrförmigen Schacht und
• Fig. 4 eine Variante zu Fig. 3 mit spezieller Hub- und Dreheinrichtung im Schnitt nach der Linie IV-IV in Fig. 3.

Embodiments of the subject invention are shown schematically in the drawings.

• Fig. 1 shows an oblique view of a stove from the front, partly in section,
• Fig. 2 an oblique view of the stove from the side with a temperature controlled elevator,
• Fig. 3 a cross section through a wood pellet stove with rotating grate in a tubular shaft and
• Fig. 4 a variant too Fig. 3 with special lifting and turning device in section along the line IV-IV in Fig. 3 ,

Way (s) for carrying out the invention

A stove after the Fig. 1 and 2 comprises a combustion chamber 1, which merges upwards into a flue 2 for the flue gases and has a grate 3 at the bottom. The grate 3 is arranged vertically adjustable within a shaft 4 by means of racks. Serves a hand crank 6, with the help of either pinion not shown self-locking engage the racks -or (as shown here) a coil spring 7 is stretched while lowering the grate 3 for the purpose of filling or loading with wood. The coil spring 7 is part of a mechanical lifting gear and outputs the stored torque via a gear 8 and a brake disc 9, acting on the permanent magnets 10 braking, to the pinion of the racks 5 from. The brake (here "eddy current brake") can be set by hand so that the torque is released very slowly (clockwise) eg within 6 hours.

As a result, takes a stroke of the grate 3 from its lowest position over the entire height of the shaft 4 then 6 hours to complete. So it is slowly raised when lowering the grate 3 to the bottom of the shaft stacked as a fuel supply wood in the total weight of, for example, 15 kg. Thus, successively either continuously or intermittently passes the firewood in the plane (focal plane or combustion zone) with lateral openings 11 for fresh air. These openings are arranged around the focal plane at the very top of the walls of the shaft 4. In the exemplary embodiment, replenishment of fresh fuel takes place from below. For lack of an air supply into the shaft (approximately from below), the fire is limited to the focal plane, which is determined by the air openings 11.

The hoist, as described so far, has a temperature-dependent control in the embodiment. A temperature sensor 12 is provided in the fume hood 2 and measures the flue gas temperature in the flue 2. Via a capillary, into which even more temperature values can be fed, an actuator 13 is operated with a piston and a piston rod which acts eccentrically on a cam 14 and this possibly twisted over a further leverage. The base of the actuator 13 is adjustable in height, whereby the parameters described below (braking power, combustion air, flue gas flap position) are jointly adjustable in the sense of a throttled or high-fire fire. A two-armed lever 15 scans one of the curves 16 and pushes the permanent magnets 10 more and more on the brake disk 9 when the exhaust gas temperature measured by the temperature sensor 12 increases. It is then stopped the hub of the elevator or slowed down and no new fuel from the shaft 4 nachgeschoben because the fire is obviously already sufficient or excessive burning and possibly should be throttled. In this sense, actuates the two-armed lever 17 which scans the cam 18, a flue 19 and thus reduces the train in the combustion chamber. A here einarmiger lever 20 feels a control curve 21 and moves flaps 22, which influence the lateral air supply via the openings 11 in the focal plane. The flaps 22 are slightly closed, and thus the fire throttled for lack of supply air. If the temperature sensor 12 detects a drop in the flue gas temperature, then the braking power is reduced, so fuel short-term refilled and it will open the flue door 19 and the flaps 22 for fresh air. The train forced in this way fanned the fire.

In order to prevent a stroke by the elevator far beyond the focal plane addition, or to set a limit for the cranking operation in pure manual operation, a stop 23 is provided above the focal plane. Logs can be lifted on this stop 23 neither in cranking operation, nor in a motor-driven elevator. For example, the crank 6 can only be turned on again (for adding wood) if a corresponding height of the fuel material in the combustion chamber has burned down. In order to allow loading of the magazine, namely the shaft 4 while lowering the grate 3 after complete consumption of wood stock in the shaft 4, the stop 23 can be swung to the side. Thus, the free access to place the logs on the grate 3 is given. A kinematic connection between the stopper 23 and the oven door causes the stopper 23 to pivot sideways as soon as the oven door opens.

According to Fig. 3 and 4 For example, an oven constructed for circular-cylindrical wood briquettes 25, 25 'has a tubular circular-cylindrical shaft 26 in which the wood briquettes 25, 25' rest on a platform as a fuel supply. These circular bricks carrying the wood briquettes 25, 25 'are formed with axial openings as a grate 27, which can be lowered manually or automatically in the shaft 26 opening from below into the combustion chamber 28 for feeding fuel and can be lowered for loading. In the area of the junction of the shaft 26 in the combustion chamber 28, a first nozzle ring 29 is provided for the supply of combustion air, in the plane of which the end face of the uppermost wood briquette 25 is located. In Fig. 3 and 4 one recognizes there a first formed as an annular space 30 Burning zone immediately on and above said end face. A second nozzle rim 31 for fresh air supply is provided in a arranged above, removable for loading with wood briquettes bottom plate and brings oxygen into a second combustion zone. The second nozzle ring 31 is located in the lateral surface of a second annular space 32, whose diameter in the embodiment is smaller than the diameter of the wood briquettes 25, 25 '. If the diameter is greater than the diameter of the wood briquettes 25, 25 ', then the removable base plate can remain in the combustion chamber 28 even during loading. In the second combustion zone, the still unburned gases from the first combustion zone are ignited. This results in a flame in the combustion chamber 28 above the second annulus 32, which effectively forms the mouthpiece of a burner.

As is known, the fresh air or combustion air supply can be forcibly controlled via a controllable fan or via valves, for example via the exhaust air temperature as a reference variable. Also, the automatic Nachschieben the fuel supply can be controlled by the exhaust air temperature to ensure a constant flame in the combustion chamber 28 at complete combustion largely exhaust-free.

Fig. 3 shows further that the grate 27 here on a carriage 33 in the shaft 26 adjustable in height (rollers 34) and in addition to the vertical central axis rotatable (roller 35) is arranged. While the hub causes fuel replenishment, rotation of the fuel supply in the well 26 results in uniform burnup and facilitates the removal of ash from the burn zone down into an ash chamber 36. For this, the annular gap 37 (eg, 6 mm) is interposed between the inner shell surface of the shaft 26 and the outer surfaces of the wood briquettes 25, 25 'are available. Also, the grate 27 has edge recesses 38, which allow falling through of ash. In contrast to the combustion residues in coal or briquettes made of coal, only a small amount of ash is produced with wood fuels, so that discharging downwards past the fuel supply is no problem. For coal briquettes, the annular gap would have to be at least 12 mm.

In Fig. 3 Furthermore, a fully automatic control of the incinerator is additionally shown. Above the combustion chamber 28 is a deduction, in which a temperature sensor 39 is provided. This is connected to a control unit 40 for guiding the same, on the one hand, the combustion air via flaps (primary air flaps, secondary air flaps) and or or metered by a blower 41 and on the other hand, the hub and the rotation of the grate 27 and thus the fuel supply (here the wood briquettes 25, 25 ') activated. As lifting and rotary drives are electric motors, eg servo motors with gears and mechanical arrangements (see Fig. 4 ) in question. Of course, for simple applications and manual crank lifting devices and (with these kinematically possibly associated) crank-operated rotary mechanisms for the grate 27 for common or separate activation of the two functions (lifting, turning) possible.

An example of an electromechanical lifting and turning device is in Fig. 4 shown, the furnace according to Fig. 3 in cross section according to the line IV-IV shows. The grate 27 is rotatably mounted on a bracket 42 which is vertically movable on a spindle 43. The spindle 43 is driven by a servo motor 44 which is controlled by the controller 40 (FIG. Fig. 3 ) is switched on when falling below an exhaust or exhaust air temperature threshold for a number of revolutions of the spindle 43. For loading with wood briquettes 25, 25 'from the top of the grate 27 is moved all the way down in the shaft 26.

Parallel to the spindle 43, a shaft 45 is mounted, which has an axial groove 46 over the entire length (see cross-sectional view). In the groove 46 engages a driver of a pinion 47, which is penetrated by the shaft 45 as a rotation axis and along the shaft 45 slides freely in the axial direction. This pinion 47 is rotatably mounted in the bracket 42 and transmits, for example by means of a toothed belt or a chain 48, the rotation of the shaft 45 on a sprocket 49. The latter is rotatably mounted on the grate 27. Thereby, a rotation of the shaft 45 is transmitted to the grate 27. The shaft 45 is over a servomotor 50 driven permanently or intermittently, wherein the controller 40 ( Fig. 3 ) issued the power on and off commands to the servo motor 50.

The console 42 passes through the lateral surface of the shaft 26 in a vertical slot, which is covered by telescopic plates ride along with the console 42 and or or the spindle 43 and the shaft 45 are located in a housing or a casing, which is closed to the outside so that no combustion air penetrates, so that the combustion is limited to the aforementioned combustion zones.

Claims (8)

1. A combustion furnace for solid fuels, in particular a chimney stove for wood, having a fire chamber (1, 28) and having a grate (3, 27), which is height-adjustably guided and is connected to a lifting mechanism, a shaft (4, 26) which is not supplied with air being provided underneath the fire chamber (1, 28) as a supply chamber for the fuel, and, in this shaft, the grate (3, 27) being provided as a platform for the fuel supply, for feeding and replenishing fuel from the supply chamber into the fire chamber (1, 28), and the lifting mechanism having a motorised drive, which is controllable as to the lifting speed for the fuel supply in dependence on the combustion, preferably by means of the exhaust gas temperature as a set point, characterized in that in the region where the shaft (4, 26) which is not supplied with air opens out into the fire chamber (1, 28), a ring of nozzles (29) that surround said opening-out region is provided, for supplying air into an annular space (30) of a first combustion zone.
2. A combustion furnace according to Claim 1, characterized in that the lifting mechanism is equipped with an energy-storing spring mechanism having a helical spring (7), which can be loaded or wound up by means of a hand crank (6) or a pull wire with simultaneous lowering of the grate (3), and in that a governor for the lifting is connected to a drive (8) that has a screw jack drive or a rack and pinion drive (5) for the grate (3), the governor being preferably a wind resistance governor as an aerodynamic restraint or a restraint having a brake controlled by the exhaust gas temperature, for example an eddy current brake with variable braking power.
3. A combustion furnace according to Claim 2, characterized in that a temperature sensor (12) for the exhaust gas temperature turns or displaces a cam disc (14) or a cam slide in dependence on temperature by way of an actuator (13), the cam disc or slide having at least one, preferably a plurality of, control cams (16, 18, 21), against which levers (15, 17, 20) engage as followers, one lever (15) carrying permanent magnets (10), which are turnable or displaceable to a greater or lesser extent over a disc (9) of an eddy current brake, a second lever (17) being kinematically connected to a flue gas flap valve (19) for temperature-dependent opening or closing, and a third lever (20) controlling flap valves (22), such as, for example, a primary air flap valve and a secondary air flap valve, in respect of their opening angle, for air supply from the side into the combustion plane.
4. A combustion furnace according to any of Claims 1 to 3, characterized in that at least one mechanical stop (23) is provided immediately above the combustion zone, which stop delimits the stroke of the lifting mechanism when it abuts against the burning fuel, and the position of which above the plane of the air supply can be adjusted.
5. A combustion furnace according to Claim 4, characterized in that the stop (23) can be swung out of the way of the combustion zone in order to fill the supply chamber, a swivel-locking feature of the stove door preferably releasing the swinging action when the door is open.
6. A combustion furnace according to any of Claims 1 to 5, characterized in that a further nozzle ring for supplying air is provided at a spacing above the first nozzle ring, which ignites, in a second combustion zone in the fire chamber, combustible gases from the first combustion zone, the second nozzle ring being in an annular space (32) that preferably has a lesser diameter than that of the annular space (30) for the first nozzle ring (29) and the annular space (32) forming the mouthpiece of a burner.
7. A combustion furnace according to any of Claims 1 to 6, characterized in that the supply chamber is formed as a circular-cylindrical, tube-like shaft (26), for accommodating preferably circular-cylindrical wood briquettes (25,25').
8. A combustion furnace according to Claim 7, characterized in that the grate (27) is arranged in the shaft (26) to be rotatable about a vertical axis, as a platform for supporting and moving the fuel supply, and has a rotary drive in addition to the lifting mechanism.

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