JP7477822B2 - Natural combustion stoves, how to use them, and pellet boxes - Google Patents

Description

Patent Law Article 30, Paragraph 2 applied. Article 30, Paragraph 2 applied, October 8, 2020, published in two leaflets (Phoenixrise)

The present invention relates to a natural combustion stove, a method for using the same, and a pellet box, and in particular to a natural combustion stove that can use both firewood and pellet fuel and can be used without any motor or electricity.

A pellet stove is a stove that uses wood pellets (hereafter simply referred to as "pellets"), which are made by compressing and molding wood and other raw materials into a certain shape, as fuel. The carbon dioxide generated by burning pellets is absorbed from the atmosphere during the tree growth process, so it does not affect the carbon dioxide concentration in the atmosphere and is so-called carbon neutral. Pellets also have the advantages of being easier to burn than firewood because they contain less moisture, have a longer burn time, and the amount fed in is easier to adjust. Meanwhile, traditionally, pellet stoves have been operated using a fuel supply motor, screw, blower fan, exhaust fan, etc.

Patent applications have been filed for pellet stoves in the past. For example, Patent Document 1, listed below, discloses a pellet burner and pellet stove that is easy to attach to existing stoves and highly portable, and that has a cylindrical fuel storage section that stores pellets and discharges them from an outlet, and a cylindrical combustion section that receives the pellets discharged from the outlet and burns them, with the fuel storage section removably attachable above the combustion section, and the combustion section being able to be installed in the upper opening of the stove. When not in use, the combustion section can be stored in the fuel storage section.

Patent Document 2 also discloses a wood pellet fuel combustion device that prevents ash and soot scattered by the combustion wind into the combustion chamber space from adhering to the inner surface of the glass window, prevents a drop in temperature inside the combustion chamber, promotes efficient combustion of wood pellet fuel, and also achieves good circulation and convection of the combustion wind within the combustion chamber to achieve visually good combustion with a well-balanced flame. The device has a configuration in which a part of the radiator tube of a heat exchanger is connected to a blowing section that supplies air toward the glass surface. In this heat exchanger, hot air is generated that is forcibly supplied by a fan and heated by the combustion wind, and this is sent to the blowing section, and the blowing section blows hot air from above to below the glass surface, thereby achieving the purpose.

Japanese Patent No. 6756963 "Pellet burner and pellet stove" Japanese Patent Application Laid-Open No. 2005-233540 "Wood pellet fuel combustion device"

Now, wood stoves are often used outdoors for recreational purposes such as camping, but if they can produce the dramatic effect of a fireplace-like burn, the atmosphere can be enhanced and the recreation can be more exciting. By "fireplace-like," I mean at least in part that a long distance structure within the combustion chamber reduces soot and burns the firewood efficiently, that the balance between intake and exhaust changes the amount of oxygen, and changes the way the firewood burns and sways, and that a long distance structure also increases heat storage.

Furthermore, if pellets, which are easier to supply as fuel and tend to stabilize the amount of heat generated and the temperature range, could be used in wood stoves, which use a natural combustion system, it would be even more convenient and preferable for recreational use. However, when using pellets in a natural combustion system with no power or electricity, problems such as backflow of combustion air and soot adhesion become an issue. There is a demand for a wood stove that can use pellets without these problems.

In other words, it would be good to provide a stove system that, even when used as a pellet stove, does not allow the combustion air to flow back, does not cause soot to adhere, and can effectively prevent soot from adhering to glass windows, allowing users to fully enjoy the flickering flames inside. In addition, it would be even better if a system could be provided that, once lit, only requires managing the fuel supply, can automatically burn at a stable temperature and amount of heat without any power or electricity, is convenient for heating, cooking, and presentations, and is easy to maintain and convenient to store and transport.

The problem that this invention aims to solve is, in light of the state of the prior art, to first provide a natural combustion stove that can achieve fireplace-like combustion. Another object of the present invention is to provide a natural combustion stove and method thereof that can use pellets as fuel and, in that case, can prevent backflow of the combustion wind and reduce soot adhesion.

The object of the present invention is also to provide a natural combustion stove and method thereof that can effectively prevent soot from adhering to the glass window of the combustion chamber and allows the user to fully enjoy the flickering flames inside, and to provide a natural combustion stove and method thereof that can automatically burn at a stable temperature and amount of heat without any power source or electricity, simply by managing the fuel supply after it has been ignited, making it convenient for heating, cooking, and presentation, and to provide a natural combustion stove and method thereof that is easy to maintain and convenient to store and transport.

The inventors of the present application have studied the above problems. As a result, they have been able to achieve fireplace-like combustion in a wood stove by providing a main airflow induction chamber to extend the distance inside the combustion chamber from the air intake to the exhaust, i.e., the airflow path. They have also developed a removable pellet storage and combustion attachment to enable the use of pellets as fuel in addition to firewood, and have confirmed that a wood stove can be used as a pellet stove by making this attachment (hereinafter referred to as the "pellet box") removable.

Furthermore, by using a special structure for the pellet box, it is possible to completely prevent backflow of air and prevent the glass window of the combustion chamber from becoming dirty with soot. In addition, once ignited, it is possible to automatically burn at a stable temperature and amount of heat, making it possible to realize a natural combustion stove that is convenient for heating, cooking, and presentation. Based on these results, the present invention was completed. In other words, the invention claimed in this patent application, or at least the invention disclosed therein, as a means for solving the above problems, is as follows.

[1] A supply unit that supplies fuel for spontaneous combustion and supplies air,
a main combustion chamber communicating with the supply section and in which combustion takes place;
and an exhaust section through which the airflow from the main combustion chamber is finally exhausted,
A main body airflow guide chamber is provided between the main body combustion chamber and the exhaust section to extend the flow path of the airflow,
The main airflow induction chamber has a front-flow side vent between the main combustion chamber and the upper part.
A downstream side vent is provided between the lower portion and the exhaust portion,
The main combustion chamber is provided with a window through which the internal flame can be seen ,
The supply unit is formed so that a pellet box, which is an attachment for storing, supplying, and burning pellet fuel, can be detachably attached to the supply unit.
The pellet box comprises a storage section for storing pellet fuel, a pellet amount adjusting means for adjusting the amount of pellet fuel supplied by natural drop from the storage section, and a combustion section for combusting the supplied pellet fuel,
The combustion section of the pellet box comprises an air inlet, a main combustion section in which the pellet fuel is combusted by air supplied from the air inlet, and a sub-combustion section provided on the side of the main combustion section;
The auxiliary combustion section is provided with a lattice structure, i.e., a charcoal grate, having a narrower spacing than the fire grate, which is a lattice structure constituting the main combustion section, for storing pellet fuel, i.e., charcoal fuel, which has been reduced in size by combustion and passed through the side of the fire grate,
The pellet box is configured so that the main combustion section communicates with the main combustion chamber when the pellet box is installed in the natural combustion stove.
A natural combustion stove.
[2] The natural combustion stove described in [1], characterized in that the main airflow guiding chamber is provided back-to-back with the rear surface of the main combustion chamber, and the exhaust section is provided in contact with the main airflow guiding chamber as well as in contact with the main combustion chamber and the supply section.
[3] A natural combustion stove as described in either [1] or [2], characterized in that the pellet box is attached as a detachable attachment.

[ 4 ] The natural combustion stove according to any one of [1], [2], and [3], characterized in that the auxiliary combustion section is formed with an inclination toward the main combustion section.
[ 5 ] The spontaneous combustion stove described in [ 4 ], characterized in that the auxiliary combustion section and the ash receiving section below it are separated by a bottom of the auxiliary combustion section.
[ 6 ] The natural combustion stove described in any one of [1], [2], [3], [4], or [5], characterized in that the combustion section is provided with an air intake guide structure that forms a flow path that narrows the air intake from the air intake port and introduces it directly into the main combustion chamber.

[ 7 ] The natural combustion stove described in [6], characterized in that the air intake guide structure is arranged to guide the intake air so that it hits the window installation surface of the main combustion chamber when the pellet box is attached to the natural combustion stove.
[ 8 ] A natural combustion stove as claimed in any one of claims 1, 2, 3, 4, 5, 6 and 7, characterized in that the bottom of the air intake is the fire grate.
[ 9 ] A natural combustion stove according to any one of [1], [2], [3], [4], [5], [6], [7], and [8], characterized in that at least one of the following <C1> and <C2> is provided :
<C1> An oven provided below the main combustion chamber <C2> A top cover provided on the top surface of the main combustion chamber

[ 10 ] A detachable pellet box that can be used with the spontaneous combustion stove described in any one of [1], [2], [3], [4], [5], [6], [7], [8], and [9] , the pellet box being an attachment for storing, supplying, and burning pellet fuel;
a storage section for storing pellet fuel;
a pellet amount adjusting means for adjusting the amount of pellet fuel supplied by gravity falling from the storage portion;
and a combustion section in which the supplied pellet fuel is combusted ,
The combustion section of the pellet box comprises an air inlet, a main combustion section in which the pellet fuel is combusted by air supplied from the air inlet, and a sub-combustion section provided on the side of the main combustion section;
The auxiliary combustion section is provided with a lattice structure, i.e., a charcoal grate, having a narrower spacing than the fire grate, which is a lattice structure constituting the main combustion section, for storing pellet fuel, i.e., charcoal fuel, which has been reduced in size by combustion and passed through the side of the fire grate,
The pellet box is configured so that the main combustion section communicates with the main combustion chamber when the pellet box is installed in the natural combustion stove.
A pellet box comprising:
[ 11 ] A method for using the spontaneous combustion stove according to any one of [ 1], [2], [3], [4], [5], [6], [7], [8], and [9] as a pellet stove, comprising:
The pellet box is attached to the natural combustion stove,
The pellet fuel is ignited by any of the following <F1>, <F2>, or <F3>.
This method of using a natural combustion stove is characterized in that combustion continues at a specified temperature range without any power or electricity thereafter.
<F1> Spontaneous ignition due to a hot ember caused by the preceding combustion of firewood fuel. <F2> Ignition by an ignition means in a state in which the spontaneous combustion stove has been preheated by the combustion of firewood fuel. <F3> Ignition by an ignition means in a state in which the spontaneous combustion stove has been preheated by the ignition means . [ 12 ] The method of using a spontaneous combustion stove described in [ 11 ], characterized in that the temperature range is 300±15°C, and that the temperature range is reached within 15 minutes after ignition.

The natural combustion stove, its method of use, and pellet box of the present invention are constructed as described above, and therefore can solve the above-mentioned problems and provide various effects. First, the natural combustion stove of the present invention can achieve fireplace-like combustion by providing a main airflow induction chamber for extending the distance inside the combustion chamber from the air intake to the exhaust, i.e., the airflow path. In other words, it can achieve some or all of the following: reducing soot and burning the fuel efficiently; changing the amount of oxygen by adjusting the balance of intake and exhaust, which changes the way the firewood burns and flickers; and increasing heat storage.

In addition, the invention of the pellet box, which is a detachable pellet storage and combustion attachment for a natural combustion stove, allows not only firewood but also pellets to be used as fuel, providing a dual-purpose natural combustion stove. Furthermore, due to the unique structure of the pellet box of the present invention, the natural combustion stove of the present invention can completely prevent backflow of air and can be used in a state that prevents the glass window of the combustion chamber from becoming dirty with soot, allowing the viewer to fully enjoy the flickering flames in the combustion chamber and enhancing the dramatic effect.

Furthermore, with the natural combustion stove, method of use, and pellet box of the present invention, once ignited, it is possible for the stove to automatically burn at a stable temperature and amount of heat, particularly when used as a pellet stove, making it convenient for both heating and as a performance tool. Therefore, it can be burned to the end without any operation other than refilling the fuel, making it easy to handle and extremely convenient. Moreover, because it provides a stable temperature and amount of heat, it is also convenient when using the stove for cooking, for example in a configuration equipped with an oven.

Furthermore, the natural combustion stove of the present invention is easy to maintain and convenient to store and transport. For example, the natural combustion stove of the present invention, which has distinctive legs, can be stably installed even if the installation location is uneven and unstable. The pellet box is also easy to attach and detach, making maintenance after use easy. In addition, since it can be used as a wood stove, the residual heat can be used to preheat the stove when it is used as a pellet stove with pellet fuel later.

This is a conceptual diagram showing the basic structure of the natural combustion stove of the present invention, and is composed of front, left and right side, rear, and plan views, with the window installation surface being the front. FIG. 2 is a diagram showing the flow of air currents in FIG. 1 . 1 is a perspective view showing an embodiment of a spontaneous combustion stove according to the present invention; FIG. 1 is a perspective view showing a method for supplying firewood fuel to a natural combustion stove according to an embodiment of the present invention (part 1). FIG. 2 is a perspective view showing a method of supplying firewood fuel to a natural combustion stove according to an embodiment of the present invention (part 2). FIG. 2 is a cross-sectional view showing the internal structure of the spontaneous combustion stove of the embodiment as seen from the front. FIG. 2 is a cross-sectional view showing the internal structure of the spontaneous combustion stove of the embodiment, as seen from the left side. FIG. 2 is a cross-sectional view showing the internal structure of the spontaneous combustion stove of the embodiment as seen from the rear. FIG. 2 is a plan view of the natural combustion stove of the embodiment. 1 is a perspective view showing an embodiment of a pellet box that can be attached and detached to a spontaneous combustion stove according to the present invention. FIG. 9 is a perspective view of the pellet box shown in FIG. 8 taken along the line IX-IX of the arrows, viewed from the direction N. FIG. 9 is a perspective view showing the pellet box shown in FIG. 8 attached to the spontaneous combustion stove of the embodiment. 11 is a schematic front view of the spontaneous combustion stove shown in FIG. 10 taken along the line XI-XI. FIG. 9 is a plan view of the pellet box according to FIG. 8 etc. 12A is a cross-sectional view taken along the line BB in FIG. 12A, illustrating the internal structure of the pellet box according to FIG. 8 and the like. FIG. 12A is a cross-sectional view taken along the line CC in FIG. 12A, illustrating the internal structure of the pellet box according to FIG. 8 and the like. FIG. 12B is a cross-sectional view taken along the line D-D in FIG. 12B, illustrating the internal structure of the pellet box according to FIG. 8 and the like. FIG. 9 is an explanatory view of the internal structure of the pellet box according to FIG. 8 etc., showing the pellet box in an installed state as viewed from the main combustion chamber side. FIG. 11 is a photograph showing the effect of the secondary combustion section of the pellet box of the embodiment (after the pellets have passed through). FIG. 11 is a photograph showing the action of the secondary combustion section of the pellet box according to the embodiment (indicating the position of pellets (fired fuel)). FIG. 11 is a photograph showing the effect of the secondary combustion section of the pellet box of the embodiment (the effect of promoting combustion of pellets on the main combustion section side). FIG. 2 is a photograph showing the internal structure of the pellet box according to the present embodiment with the top lid opened. FIG. 2 is a photograph showing the use of the spontaneous combustion stove of the embodiment (overview). FIG. 2 is a photograph showing the use of the natural combustion stove of the embodiment (burning in the main combustion chamber).

The present invention will now be described in detail with reference to the drawings.
FIG. 1 is a conceptual diagram showing the basic structure of the natural combustion stove of the present invention, and is composed of a front view (a), a left side view (b), a right side view (c), a back view (d), and a plan view (e) with the window installation surface as the front. Also, FIG. 1-2 is a diagram showing the flow of air current in FIG. 1. As shown in these figures, the natural combustion stove 10 of the present invention is equipped with a supply section 1 that supplies fuel for natural combustion and supplies air, a main combustion chamber 2 that is connected to the supply section 1 and in which combustion takes place, and an exhaust section 3 from which the air current from the main combustion chamber 2 is finally exhausted, a main air current induction chamber 4 is provided between the main combustion chamber 2 and the exhaust section 3 to extend the circulation path of the air current, the main air current induction chamber 4 has a front flow side vent 5 between the main combustion chamber 2 at its upper part and a rear flow side vent 6 between the exhaust section 3 at its lower part, and the main combustion chamber 2 has a window 7 through which the internal flame can be seen. The window 7 can be constructed using heat-resistant glass, etc. The element indicated by the reference number 9 in the figure is the lower structure, mainly consisting of an ash catcher. A typical example of a natural combustion fuel that can be used in the natural combustion stove 10 is firewood. The following explanation will be centered on firewood.

In the figure, the window 7 is provided vertically on the front of the main combustion chamber 2, but the present invention is not limited to this. In other words, a configuration in which a window is provided on at least one of the left side, right side, and front sides is also within the scope of the present invention. However, if the space above the supply unit 1 is used as a space for attaching a pellet box, which will be described later, there is no need to provide a window on the right side. In addition, an opening and closing door is provided on the main combustion chamber 2, but the preferred side for providing this is a position adjacent to the supply unit 1 in terms of handling the supplied firewood. In that case, it is preferable to provide the opening and closing door on the front, and the window 7 is located on the front. There may be a window on the left side in addition to the front, but a sufficient presentation effect can be obtained just by providing it on the front.

In this natural combustion stove 10 with such a configuration, fuel for natural combustion such as firewood fuel is supplied and air is supplied in the supply section 1, and combustion based on the fuel supplied by the supply section 1 occurs in the main combustion chamber 2. The airflow (including the combustion wind) F caused by the combustion rises inside the main combustion chamber 2, flows into the main airflow induction chamber 4 through the front side vent 5 provided between the main combustion chamber 2 and the main combustion chamber 2, flows inside the main airflow induction chamber 4 toward the rear side vent 6 located at the bottom, flows into the exhaust section 3 through the rear side vent 6, and rises inside the exhaust section 3 before being exhausted. The flame of combustion inside the main combustion chamber 2 can also be seen through the window 7.

In this natural combustion stove 10, the airflow F in the main combustion chamber 2 is not directly exhausted from the exhaust section, but flows through the main airflow induction chamber 4, with the flow path of the airflow F extended, before entering the exhaust section 3 and being exhausted. Therefore, a fireplace-like effect can be obtained, with sufficient combustion and heat storage effects due to the long flow path. Note that this natural combustion stove 10 is not a fireplace that is a structure that is installed inside or outside a building. As will be described later in the examples shown in each figure from Figure 2 onwards, it is a portable stove that can be configured to be easily carried by one adult, and its main intended use is to take it outdoors, such as for camping.

As mentioned above, the supply section 1 supplies firewood fuel and supplies air, where the supplied firewood fuel is ignited to cause primary combustion, and the incomplete combustion gases produced in the primary combustion are burned in the main combustion chamber 2 by oxygen from the supplied air, i.e., secondary combustion occurs. The natural combustion stove 10 of the present invention is equipped with the main airflow induction chamber 4, which provides a long airflow path, which is advantageous for complete combustion of the supplied fuel, and sufficient and good combustion is achieved.

Furthermore, firewood fuel can be supplied not only from the supply unit 1 but also from the main combustion chamber 2. In this method, a door provided in the main combustion chamber 2 is opened to supply firewood fuel into the main combustion chamber 2. If the door is long and vertical, it is convenient to put firewood vertically into the main combustion chamber 2, and it can be burned by stacking it horizontally or vertically as desired. In other words, the main combustion chamber 2 is not limited to secondary combustion. When firewood fuel is directly placed in the main combustion chamber 2, primary combustion and subsequent secondary combustion are carried out in the same chamber. Note that while conventional camping wood stoves stack firewood horizontally, the natural combustion stove 10 of the present invention allows firewood to be stacked vertically as well, allowing for a variety of vertical and horizontal stacking.

The airflow F caused by the combustion rises inside the main combustion chamber 2. Therefore, the combustion flames flicker as they extend vertically, and this can be seen through the window 7. As shown in the figure, the main combustion chamber 2 and the exhaust section 3 are in surface contact in part, and heat in the main combustion chamber 2 is easily transferred to the exhaust section 3. The exhaust section 3 is also in surface contact with the supply section 1, where the firewood fuel is ignited and the primary combustion takes place, and this heat is also easily transferred to the exhaust section 1. In other words, the main airflow induction chamber 4 is provided back-to-back with the rear of the main combustion chamber 2, and the exhaust section 3 is provided in contact with the main airflow induction chamber 4 as well as with the main combustion chamber 2 and the supply section 1.

Therefore, a sufficient updraft is generated in the exhaust section 3, creating a state in which exhaust is promoted. As described above, the airflow F that rises in the main combustion chamber 2 flows into the main airflow induction chamber 4 through the front-stream side vent 5 located near the ceiling, flows downward toward the rear-stream side vent 6 located below, flows into the exhaust section 3 through the rear-stream side vent 6, and rises inside it before being exhausted. The flow of this airflow F is promoted by the creation of a state in the exhaust section 3 that creates an updraft and promotes exhaust.

The main body airflow induction chamber 4 is an element for extending the flow path of the airflow F, but its specific structure is not limited as long as it is a structure that can extend the flow path. However, as shown in the example described later in FIG. 2 etc., by forming the main body airflow induction chamber 4 adjacent to/contacted by a partition, with the interior of a roughly rectangular parallelepiped divided by a wall structure or partition plate, sufficient and good effects can be obtained. As shown in (e) in the figure, it is preferable to form the cross-sectional area of the main body airflow induction chamber 4 smaller than the cross-sectional area of the exhaust section 3. This is because the airflow will flow more smoothly.

As mentioned above, the front-flow vent 5 of the main airflow induction chamber 4 is provided at the top, and the rear-flow vent 6 is provided at the bottom, in order to make the flow of the airflow F smoother. With this configuration, the airflow F generated by the combustion in the main combustion chamber 2 rises within the chamber 2, then descends within the main airflow induction chamber 4 into which it flows, and finally rises in the exhaust section 3, forming a U-turn-shaped flow. And, with the main airflow induction chamber 4 and exhaust section 3 of the above-mentioned partition structure, when viewed to the end of the exhaust section 3, a flow path roughly twice the vertical dimension of the main combustion chamber 2 is added to the main combustion chamber 2, which significantly extends the circulation path.

The specific shape of the front-stream side vent 5 is not limited, but as shown in (d) of the figure, it can be preferably a rectangular gap of appropriate narrowness extending horizontally. The specific shape of the rear-stream side vent 6 is also not limited, but as shown in (c) of the figure, it can also be a rectangular gap of appropriate size. In short, it is sufficient if the shape can facilitate the smooth flow of air to the end of the exhaust section 3.

The present invention will be described below with reference to examples. However, the present invention is not limited to the size and other specific configurations and specifications in the examples.
Fig. 2 is a perspective view showing an embodiment of the natural combustion stove of the present invention. Fig. 3 is a perspective view showing a method for supplying firewood fuel to the natural combustion stove of the embodiment (part 1), and Fig. 3-2 is a perspective view showing a method for supplying firewood fuel to the natural combustion stove of the embodiment (part 2). As shown in these figures, the natural combustion stove 210 of the present invention is equipped with a supply section 21 for supplying firewood fuel W and supplying air, a main combustion chamber 22 connected to the supply section 1 and in which combustion takes place, and an exhaust section 23 from which the airflow from the main combustion chamber 22 is finally exhausted. Between the main combustion chamber 22 and the exhaust section 23, a main airflow induction chamber (not shown in these figures) is provided for extending the circulation path of the airflow. The main airflow induction chamber is provided with a front-stream side vent (not shown in these figures) between the main combustion chamber 22 at its upper part and a rear-stream side vent (not shown in these figures) between the main combustion chamber 22 at its lower part, and a window 27a through which the internal flame can be seen is provided in the main combustion chamber 22. In this embodiment, a window 27b is also provided in the supply section 21.

The lower structure 29 of the natural combustion stove 210 of this embodiment is configured with an ash receiving section (not shown in these figures) that receives ash that falls from the main combustion chamber 22 after fuel combustion, an oven 29V, and legs 29F. In particular, by providing the oven 29V, this stove 210 can be used not only for heating but also for cooking. This effect is even greater when used as a pellet stove by attaching a pellet box, which will be described later. This is because when used as a pellet stove, the heat quantity and temperature range are more stabilized.

The top surface of the main combustion chamber 22 is provided with a top lid 221 that can be opened and closed. When the top lid 221 is closed, cooking such as boiling a pot can be performed by placing it on the top, and when the top lid 221 is open, cooking such as grilling or searing can be performed using the flame inside the main combustion chamber 22. The element that protrudes to the side of the top of the main combustion chamber 22 is a shelf 222, on which cooking utensils and ingredients before and after cooking can be placed. The shelf 222 can be folded up or stored inside the main combustion chamber 22 when not in use.

The main combustion chamber 22 is provided with an opening/closing door 223, and a window 29a is provided in the opening/closing door 223. As shown in FIG. 3, the firewood fuel W is supplied from the opening/closing door 213 of the supply unit 21 by opening it, and is ignited and primary combustion occurs. The firewood is supplied horizontally here. On the other hand, as shown in FIG. 3-2, the firewood fuel W can also be supplied from the opening/closing door 223 of the main combustion chamber 22 by opening it. As shown in the figure, the firewood can be supplied vertically here. Both the window 29a and the window 29b provided in the supply unit 21 can be made of a translucent material such as heat-resistant glass so that the combustion inside can be seen. In particular, through the large vertical window 29a, the flickering flames inside the main combustion chamber 22 can be clearly seen, providing an appearance and performance effect similar to that of a fireplace.

The number and installation positions of the intakes 214, 215, etc. for adjusting the strength of the combustion are not limited to the example shown in the figure and can be designed as appropriate. The effects of the fireplace have already been described, but in addition, many fireplaces are designed to burn the fire at a long distance so that tertiary or quaternary combustion is performed to burn efficiently and reduce soot, and the balance of intake and exhaust can be adjusted to adjust the burning time and temperature. By adjusting these, the amount of oxygen changes, and the way the firewood burns and flickers changes. The natural combustion stove 210 of this embodiment has a total of four intakes, two for primary combustion and two for secondary combustion. Therefore, there are four patterns of intake adjustment. When not used as a pellet stove, the intake on the primary combustion side can be closed to suppress the amount of oxygen supplied and burn for a long time.

The natural combustion stove 210 of this embodiment has a handle 219 and other features, making it easy to carry by hand and suitable for outdoor use. Incidentally, the size of the stove 210 of this embodiment is 36 cm wide x 32 cm deep x 73 cm high, with a total weight of approximately 22 kg. Of course, these specifications can be modified as needed. In addition, a chimney connection part 239 is provided at the top of the exhaust part 23, where a chimney can be added. In this example, five chimney members are provided, which can be stored inside the exhaust part 23 and the main combustion chamber 22 when not in use. Furthermore, in this embodiment, the structure is designed to make it easy to attach and detach replacement parts with maintenance in mind.

Furthermore, the natural combustion stove 210 of this example is characterized in that its legs 29F are a four-legged stable installation structure or a four-legged horizontal installation structure described in Patent No. 3594299. Of course, the legs of the present invention are not limited to such configurations, but the legs 29F of this example are convenient when installing in places where it is difficult to maintain a level surface, such as uneven ground or slopes. The legs 29F have a structure that supports a workpiece with four legs, and are composed of two legs fixed to the workpiece and two legs connected by a curved section having an arc, and are a four-legged stable installation structure or a four-legged horizontal installation structure that is connected so that the curved section and the workpiece can slide in the arc direction.

Figures 4, 5, and 6 are cross-sectional views showing the internal structure of the embodiment of the natural combustion stove from each direction (front, left side, and rear). All are perspective views from the diagonal left direction. Also, Figure 7 is a plan view of the embodiment of the natural combustion stove. These figures are views of the state in which a pellet box, which will be explained later in Figure 8, etc., is attached. In the natural combustion stove 210 of this example with the configuration shown in the figures, the airflow in the main combustion chamber 22 is not directly exhausted from the exhaust section 23, but flows through the inside of the main airflow induction chamber 24 with the flow path of the airflow extended by the main airflow induction chamber 24, enters the exhaust section 23, and is exhausted.

In other words, the airflow rotates and rises inside the main combustion chamber 22, passes through the front-side vent 25 from the ceiling and enters the main airflow induction chamber 24 at the back, passes through the rear-side vent 26 from the floor of the main airflow induction chamber 24 and enters the exhaust section 23, rises inside the exhaust section 23, and is exhausted. This extended airflow path allows for sufficient combustion and heat storage, a fireplace-like effect.

The supply section 21 supplies firewood fuel and supplies air, where the supplied firewood fuel is ignited to perform primary combustion, and the incompletely burned gases resulting from primary combustion are burned in the main combustion chamber 22 by oxygen from the air supply, i.e., secondary combustion. The natural combustion stove 210 of the present invention is provided with the main airflow induction chamber 24, which extends the airflow path, increasing heat storage and favoring complete combustion of the supplied fuel, resulting in sufficient and good combustion. In addition, the cross-sectional area of the main airflow induction chamber 24 in the flow direction can be configured to be slightly larger than the cross-sectional area of the exhaust section 23 in the flow direction. This can promote and smooth the flow of air from the supply section 21 to the end of the exhaust section 23.

The primary combustion in the supply section 21 heats the exhaust section 23 located immediately behind it, promoting the upward air current within the exhaust section 23, which also promotes the formation of an air current from the intake to the exhaust. The planar/three-dimensional structure of the entire natural combustion stove 210 in this example itself has the effect of preventing backflow. Heat shields are provided on the inner surfaces of the main combustion chamber 22, main air current induction chamber 24, and exhaust section 23. In FIG. 7, the boundary between the internal main combustion chamber 22 and main air current induction chamber 24 is indicated by a dashed line.

Figure 8 is a perspective view showing an embodiment of a pellet box that is detachably attached to the natural combustion stove of the present invention. Also, Figure 9 is a perspective view from the N direction looking down on the IX-IX cross section of the pellet box shown in Figure 8, Figure 10 is a perspective view showing the pellet box shown in Figure 8 attached to the natural combustion stove of the embodiment, and Figure 11 is a schematic front view of the XI-XI cross section of the natural combustion stove shown in Figure 10. As shown in these figures, the pellet box 28, which is an attachment for storing, supplying, and burning pellet fuel, is basically configured to be detachably attached to the supply section 21 of the natural combustion stove 210.

The pellet box 28 may be traded separately as an attachment independent of the natural combustion stove 210, or may be a removable attachment that is attached to the natural combustion stove 210, or may be configured as a part of the natural combustion stove 210. In any case, as can be seen by comparing FIG. 10 with FIG. 2, the pellet box 28 can be attached to the supply unit 21 simply by fitting the pellet box 28 from above into the air intake 214 of the supply unit 21 and fixing it in place by screws or the like.

Therefore, it is advisable that the lower part of the pellet box 28, which is the fitting part, is shaped to fit exactly into the air intake port 214 of the supply section 21. The pellet box 28 can be removed by releasing the specified fastenings and pulling it upward. Note that Figure 11 is the same as Figure 4 above, but the former explains the pellet box 28, and the latter explains the airflow induction action inside the natural combustion stove 210 in combination with Figures 5 and 6. Figures 5 to 7 above also show the pellet box 28 attached to the natural combustion stove 210.

Figure 5 shows a view of part of the pellet box 28 from inside the main combustion chamber 22. When the natural combustion stove 210 is not used as a pellet stove, the pellet box 28 is not attached, and the space between the main combustion chamber 22 and the supply section 21 is opened wide as the supply section-main combustion chamber opening 228, allowing firewood fuel to be supplied horizontally from the supply section 21. However, when the pellet box 28 is attached, as shown in the figure, its lower structure (the combustion section described below, more specifically the main combustion section-fire grate) is located exactly at the supply section-main combustion chamber opening 228, forming the boundary with the main combustion chamber 21.

Figure 6 above also shows that a pellet box 28 is attached to the supply section 21 which is adjacent to the exhaust section 23, that the pellet box 28 is also in contact with the exhaust section 23, and that the pellet box 28 can be formed so that when attached, it is at the same height as the natural combustion stove 210. Figure 7 above also shows that the pellet box 28 has a shape that allows it to be attached in a way that matches the shape of the supply section 21.

In the case of a natural combustion type pellet stove, it is generally necessary to preheat the entire stove and smooth the air flow inside the stove from the intake port to the end of the exhaust section before ignition; otherwise, there is a risk of smoke and flames backflowing. The natural combustion stove 210 of the present invention promotes the formation of an appropriate air flow inside by the structure in which the above-mentioned air flow path is extended and the structure in which the main combustion chamber 22 and supply section 21 where combustion takes place are adjacent to the exhaust section 23 to promote the generation of an updraft in the exhaust section 23. Even when the natural combustion stove 210 of the present invention is used as a pellet stove by attaching the pellet box 28, the combustion in the pellet box 28 heats the exhaust section 23 immediately behind it, promoting the formation of a smooth air flow from intake to exhaust by natural convection and updraft.

As shown in Figures 8 and 9, the pellet box 28 is composed of a storage section 281 for storing pellet fuel, a pellet amount adjustment means 282 for adjusting the amount of pellet fuel supplied by natural fall from the storage section 281, and a combustion section 283 for burning the supplied pellet fuel. The pellets can be stored inside the storage section 281 by opening the top lid. A storage amount confirmation window 281S for checking the storage amount may also be provided. The size of the pellets, i.e., wood pellet fuel, is usually about 6 mmφ x 30 mm. The storage section 281 of the pellet box 28 in this example can store a maximum of about 1.7 kg of pellets, and the maximum amount can be stored to continue the burning state for more than one hour, but such specifications and performance are not limited and can be designed as appropriate.

As the pellet amount adjustment means 282, as shown in the figure, a pellet amount adjustment plate that separates the storage section 281 and the combustion section 283 of the pellet box 28 can be suitably used. The pellet amount adjustment plate is a substantially rectangular plate with a hook-shaped rear end, and by appropriately using the mounting method of inserting the hook part into the slit between the storage section 281 and the combustion section 283 with the hook part facing upward as shown in the figure, or the mounting method of inserting the hook part facing downward, it is possible to block the falling of pellets from the storage section 281 to the combustion section 283, freely adjust the gap width between the storage section 281 and the combustion section 283, or fully open it. The optimal gap width is one that can suppress the falling of the bottom layer of pellets from above by pressing them from the side.

In this way, the pellet box 28 uses the pellet amount adjustment means 282 to adjust the supply and stop of the pellets stored in the storage section 281 to the combustion section 283, and the pellets that are naturally dropped from above are burned in the combustion section 283. Details of the combustion method will be described later using Figures 12 and 13.

Figures 12A to 13E are diagrams explaining the internal structure of the pellet box combustion section, of which Figure 12A is a plan view of the pellet box shown in Figure 8 etc., Figure 12B is a cross-sectional view taken along the line B-B in Figure 12A, and Figure 12C is a cross-sectional view taken along the line C-C in Figure 12A. Figure 13D is a cross-sectional view taken along the line D-D in Figure 12B, and Figure 13E is a view of the pellet box in the installed state as seen from the main combustion chamber side. As shown in these figures, especially Figure 12B, the combustion section 283 of the pellet box 28 is basically composed of an air inlet 284, a main combustion section 285 where the pellet fuel is burned by air supplied from the air inlet 284, and a sub-combustion section 286 provided to the side of the main combustion section 285.

As shown in particular in Figures 12C, 13D, and 13E, the auxiliary combustion section 286 is provided with a lattice structure (fire grate) 286G with narrower spacing than the grate 285G for storing pellet fuel (fuel fuel) that has been reduced in size by combustion and passed sideways through the lattice structure (fire grate) 285G that constitutes the main combustion section 285. A characteristic feature of this pellet box 28 is that when it is attached to the spontaneous combustion stove 210, the main combustion section 285 is formed to communicate with the main combustion chamber 22.

In the combustion section 283 of the pellet box 28, with this configuration, pellets are naturally dropped from the storage section 281 while the supply amount is adjusted by the pellet amount adjustment means 282, and air is supplied from the air inlet 284, and the pellets are burned in the main combustion section 285, that is, on the grate 285G, by appropriate ignition or preheating. The pellets are gradually reduced in size by the combustion in the main combustion section 285. This allows them to pass through the gaps in the grate 285G.

Because the secondary combustion section 286, which is made up of a lattice structure with a narrower spacing than the grate 285G, is provided on the side of the main combustion section 285, the reduced-size ignited fuel passes through the gaps in the grate 285G and moves to the secondary combustion section 286 side, where it continues to burn while placed on the ignited grate 286G of the secondary combustion section 286. Since the ignited grate 286G forms the bottom of the air intake 284, it directly receives the air intake from the air intake 284. Therefore, the combustion of the ignited fuel on the ignited grate 286G continues well and vigorously, and this combustion has the effect of promoting the combustion of the pellets in the main combustion section 285 through the grate 285G.

The main combustion section 285 of the combustion section 283 can be divided into an upper section, which is the position where ignition takes place directly below the pellet amount adjustment means 282, a lower section facing the grate of the main supply section 21, and a middle section in between. The upper section is the area where falling pellets are ignited by preheating or ignition means and combustion begins, the middle section is the area where pellets that have fallen as combustion progresses and are igniting burn even more intensely due to the air supply from the air supply port 284, and the lower section is the area where pellets that have fallen further as combustion progresses and are igniting burn even more intensely due to the air supply from the air supply port 284, and then burn to ash, toward the end of combustion.

As shown in Figures 12C and 13E, the grate 285G of the main combustion section 285 can be configured in three stages, upper, middle, and lower, with each stage roughly corresponding to the upper, middle, and lower sections described above. Thus, in the upper stage of the grate 285G, falling pellets are ignited by preheating or ignition means and combustion begins, in the middle stage, the falling pellets burn vigorously as combustion progresses, and in the lower stage, the falling pellets continue to burn vigorously while still burning strongly, turning to ash and then to ashes, toward the end of combustion. After combustion ends, the ash falls through the grate into the ash receiver.

As described above, it is desirable that the pellets ignite and start burning immediately after falling from the storage section 281 into the combustion section 283. However, while the pellets ignite and start burning first at the top and burn well in the middle and lower sections, ignition and start of combustion at the top are not always smooth. Therefore, in the present invention, a secondary combustion section 286 is provided on the side of the top of the main combustion section 285, or on the side of the upper section of the grate 285G in Figure 12C etc. In other words, the secondary combustion section 286 is not a grate 285G facing the main combustion chamber 22 side, but is provided on the intake port 284 side across the grate 285G facing the intake port 284 side.

With this configuration, the small pellets (ignited fuel) that have passed through the grate 285G burn well in the secondary combustion section 286 consisting of the ignition grate 286G due to the air supply from the air supply port 284, and the heat and flames from the fire grate 285G facilitate and promote the ignition and combustion of the pellets in the upper part (upper part) of the main combustion section 285. As a result, the pellets in the upper part (upper part) gradually become smaller due to smooth combustion and naturally fall to the middle part (middle part) and lower part (lower part), promoting combustion, which also smooths the movement of the pellets and prevents pellet clogging.

The size of the gaps (slits) in the fire grate 285G that constitutes the main fuel section 285 and the charcoal grate 286G that constitutes the secondary combustion section 286 can be designed appropriately, taking into consideration the size of the pellets used and the size of the charcoal fuel that should be held in order to maintain the combustion promotion effect of the main combustion section 285 on unignited, unburned, and low-burnt pellets. If the slits are too narrow, the pellets and charcoal fuel will become clogged, and conversely, if they are too wide, they will spill out immediately and the supplied air will simply pass through, preventing good combustion and preventing the secondary combustion section from promoting the combustion of unignited, unburned, and low-burnt pellets. The slit size is designed taking these points into consideration.

As shown in FIG. 12B and the above-mentioned FIGS. 9 and 11, the main combustion section 285 of the pellet box 28 according to this embodiment is shaped so that it narrows downward and has a constricted cross-sectional area. This shape makes it possible to prevent pellets from spilling out due to the gradual reduction in pellet size as combustion progresses. In other words, the pellets that fall naturally from the storage section 282 are filled in the main combustion section 285 as a pellet layer consisting of multiple pellets, and this filled state is maintained without easily falling downward. This is because the inner surface of the grate 285G, which is the outer shell of the main combustion section 285, applies pressure to the pellet layer.

The side shape of the main combustion section 285 is shaped to shrink downward so that this pressure can be maintained throughout the upper, middle, and lower parts of the main combustion section 285 even as the pellets become smaller in size. This shape is effective not only because it prevents pellets from spilling out, but also because air is supplied from the air inlet 284 to the pellets that are held in position within the main combustion section 285 while becoming smaller, i.e., igniting, so that the pellets can continue to burn while being fixed in a state that does not let them escape (do not spill out).

Figures 14 to 16 are photographs showing the action of the secondary combustion section of the pellet box according to the embodiment. In order, Figure 14 shows after the pellets pass through, Figure 15 shows the position of the pellets (fired fuel), and Figure 16 shows the combustion promotion action on the pellets on the main combustion section side. As shown in these figures, especially Figure 15, the secondary combustion section 286 of the pellet box 28, i.e., the charcoal grille 286G, can be formed with an inclination toward the main combustion section 285. The inclination is an inclination with a depression angle toward the main combustion section 285. As mentioned above, the secondary combustion section 286 is provided at the upper position of the main combustion section 285, i.e., corresponding to the position where the pellets should be ignited. Note that Figures 9, 11, and 12B also show a configuration in which the secondary combustion section 286 is formed at an angle inclined toward the main combustion section 285.

With this configuration, pellets, i.e., ignited fuel P, that fall through the gaps in the grate 285G and into the secondary combustion section 286 due to the reduction in size caused by combustion (Figure 14) do not move away from the main combustion section 285 and the grate 285G, but remain in a position close to the grate 285G (Figure 15). This causes active combustion to occur as air is directly supplied from the air intake 284 just above (Figure 16), and the resulting flames and heat promote the ignition and combustion of the pellets just beyond the grate 285G.

The ignited fuel P, which is made by burning pellets and reducing its size, passes through the gaps in the fire grate 285G and continues to burn in the secondary combustion section 286. However, initially it does not pass through the gaps in the fire grate 286G, so the ignition and combustion promotion effect on the pellets on the main combustion section 285 side is obtained for a while. As the combustion progresses, the ignited fuel becomes small enough to pass through the gaps in the fire grate 286G, and falls naturally through the gaps in the fire grate 286G to the bottom of the secondary combustion section. The gap (slit) spacing of the fire grate 286G can be designed taking into consideration the smoothness of the air supply and the size of the ignited fuel that can maintain the ignition and combustion promotion effect.

The above describes the ignition and combustion promotion effect of the auxiliary combustion section 286 that contributes to unignited, unburned, and low-burned pellets, but this effect is supplementary. In other words, the ignition and combustion promotion effect on unignited, unburned, and low-burned pellets is mainly achieved by the combustion heat from the lower and middle parts of the main combustion section 285. However, although it is supplementary, the effect of the auxiliary combustion section 286 is great, and the ignition and combustion promotion effect is significantly different with or without it. In addition, the bottom of the intake port 284 is the charcoal grille 286G, so the charcoal grille 286G burns charcoal fuel from time to time, and you can easily see how it affects the main combustion section 285, which also has a visual effect that you can enjoy.

As shown in Figures 9 and 11 above, the pellet box 28 according to this embodiment can be configured so that the auxiliary combustion section 286 and the ash receiving section 29T below it are blocked off by the auxiliary combustion section bottom 287. In other words, there is no need to have a structure in which the bottom of the charcoal grille 286G is open toward the ash receiving section 29T, and the ash is sent by the airflow to the main combustion chamber 22 side without accumulating at the auxiliary combustion section bottom 287. It is believed that the blocked structure at the bottom of the auxiliary combustion section 286 restricts the air flow path, which facilitates airflow control toward the main combustion chamber 22 side.

As shown in Figures 4, 5, 7, etc., when the pellet box 28 is attached to the natural combustion stove 210, the main combustion section 285 is formed so that it communicates with the main combustion chamber 22. As a result, the airflow caused by the pellet combustion flows through the main combustion chamber 22 - main airflow induction chamber 24 - exhaust section 23 flow path, and the flames caused by the combustion can be seen through the window 27a of the main combustion chamber 22. A method that can make the control of such airflow smoother and also achieve other effects will be explained next.

As shown in Figures 9, 12C, 13D, and 13E, the combustion section 283 of the pellet box 28 in this embodiment can be configured to have an air intake guide structure 288 that narrows the intake air from the air intake port 284 and forms a flow path that directly introduces it into the main combustion chamber 22. The air intake guide structure 288 does not communicate with the storage section 281 and the main combustion section 285, but communicates with the auxiliary combustion section 286 and the intake port 282 on the upstream side thereof, and is structured to be open to the main combustion chamber 22 by a slit, so that the air sucked in from the air intake port 282 enters the air intake guide structure 288 from the charcoal grille 286G of the auxiliary combustion section 286, and flows into the main combustion chamber 22 through the grille (air flow grille) 288G provided on the main combustion chamber 22 side.

Figure 17 is a photograph showing the internal structure of the pellet box of this embodiment with the top lid open. As shown in the figure, the air intake induction structure 288 is provided at one end of the main combustion section 285 of the pellet box 28, isolated from the storage section 281 and also isolated from the main combustion section 285. The air intake induction structure 288 is used to guide the airflow from the intake port 284 to the main combustion chamber 22, but pellets are not supplied or burned inside it.

The air intake guide structure 288 generates an airflow from the air intake port 284 to the main combustion chamber 22 that is not directly related to pellet combustion, and this allows the soot generated by fuel combustion to be smoothly used for secondary combustion in the main combustion chamber 22 and beyond. As illustrated in each figure, the air intake guide structure 288 is positioned so that the induced airflow hits the window 27a installation surface of the main combustion chamber 22 when the pellet box 28 is attached to this natural combustion stove 210, thereby effectively preventing soot from adhering inside the main body. In particular, soot adhesion to the window 27a etc. can be prevented, and the transparency of the window 27a etc. can be maintained, allowing the internal combustion state, such as the flickering of the flame, to be clearly seen.

In this embodiment, the "position where the induced airflow hits the installation surface of the window 27a of the main combustion chamber 22 when the pellet box 28 is attached to the natural combustion stove 210" is the left end of the main combustion section 285 as shown in FIG. 17. The airflow passing through the air supply guide structure 288 passes through the airflow lattice 288G and flows into the main combustion chamber 22, hitting the installation surface of the window 27a. In other words, the airflow is blown directly onto the window 27a and flows in a regulated manner along the wall surface, so that even if soot is about to adhere to the window 27a, it is immediately blown away, effectively preventing soot from adhering to the window 27a. In other words, it is desirable to provide the air supply guide structure 288 at the end of the combustion section 283 so that the airflow can be sent along the inner wall side of the main combustion chamber 22.

Figures 18 and 19 are photographs showing the use of the natural combustion stove of the embodiment, the former showing an overview and the latter showing the combustion in the main combustion chamber. Both are examples of use as pellet stoves with a pellet box 28 attached. As shown in these, the pellet combustion can be clearly seen through the window 27a, and in particular in Figure 19, the flames can be seen vigorously blowing out from the combustion section 283 side of the pellet box 28 into the main combustion chamber 22. The flames are also blowing along the window 27a, demonstrating the effect of the air intake induction structure 288.

The natural combustion stove of the present invention can use both firewood and pellets at the same time, but this is not necessary. Using both fuels at the same time produces a significant amount of heat, so it is more preferable to use only one fuel. When the natural combustion stove 210 is used as a firewood stove, it burns at a temperature about 100°C higher than when pellets are used. Therefore, even if soot forms, it burns out quickly and is less likely to adhere to the window 27a, etc.

The natural combustion stove of the present invention, which can also be used as a pellet stove, has the following three features that enable it to prevent the backflow of smoke caused by the chimney effect, which is a common problem with conventional natural combustion pellet stoves.
1) Airflow guidance structures in pellet boxes, such as air intake guidance structures.
2) Smooth ignition and combustion not only in the middle and lower parts of the main combustion section of the pellet box, but also in the upper part, maintaining a continuous void distribution within the pellet layer, thereby allowing smooth airflow, which in turn allows pellets to fall naturally intermittently.
3) The overall structure of the stove, including the main airflow induction chamber and the structure that promotes the generation of updrafts in the exhaust section. Also, the extension of the airflow path that results from this.

As shown in FIG. 2 and other figures, the supply unit 21 can be provided with two air intakes. One of them is the intake 214 where the pellet box 28 is attached. When firewood is used as fuel, air flows over or beside the firewood. This is the same air intake method as in conventional camping wood stoves. On the other hand, the intake 215 is designed to allow air to flow above and below the grate. In particular, the air that hits the grate from below burns firewood and embers for a long time. This is effective for combustion when fuel such as firewood has accumulated on the bottom. When using a pellet stove with the pellet box 28 attached, the intake 215 can be closed and only the intake 284 can be used for air intake, which is more effective.

The pellet box of any of the configurations described above using Figures 8 to 13E, etc., is also within the scope of the present invention. While the natural combustion stove of the present invention is based on the use of natural combustion fuel such as firewood, it can also use pellet fuel, and by making the pellet box detachable from the main body, maintenance of both the main body and the pellet box is easy and convenient.

The present invention also includes a method of using a natural combustion stove 210 having any of the above-described configurations as a pellet stove, in which a pellet box 28 is attached to the natural combustion stove 210, the pellet fuel is ignited by any of the following <F1>, <F2>, or <F3>, and then combustion continues in a specified temperature range without any power or electricity.

<F1> Spontaneous ignition due to embers created by the preceding combustion of firewood fuel By burning firewood first, the pellets can be ignited by the embers.
<F2> Ignition by an appropriate ignition means outside the invention, such as a gas burner, while the natural combustion stove 210 is being preheated by burning firewood fuel. Preheating can be performed by heating the main body (glass window surface), chimney (exhaust tower), etc. with a gas burner.
<F3> Ignition by an ignition means outside the invention in a state where the spontaneous combustion stove 210 has been preheated by an ignition means outside the invention. First, the stove 210 is made to burn firewood, and then the pellets are burned using the residual heat as preheat.

By using this method, the natural combustion stove 210 can stably maintain a temperature of 300±15°C when using pellets as fuel, and can even stably maintain a temperature of 300±10°C. This temperature range can be reached within 15 minutes after ignition, and even more so in about 10 minutes, and thereafter, a constant temperature state at this high temperature can be maintained throughout the combustion. As mentioned above, the embodiment can store a maximum of 1.7 kg of pellet fuel, but by storing the maximum amount, combustion can continue for about 1 hour and 10 to 20 minutes.

The natural combustion stove, method of use, and pellet box of the present invention provide many advantages, such as the ability to achieve fireplace-like combustion and the ability to be used effectively not only as a firewood stove but also as a pellet stove. As such, this invention has great industrial applicability in all fields of natural combustion stove use, including outdoor recreational uses such as camping, as well as in the manufacturing field and all related fields.

1, 21...Supply section 2, 22...Main combustion chamber 3, 23...Exhaust section 4, 24...Main airflow induction chamber 5, 25...Front flow side vent 6, 26...Rear flow side vent 7, 27a, 27b...Window 9, 29...Lower structure 10, 210...Natural combustion stove 28...Pellet box 29F...Leg 29T...Ash receiving section 29V...Oven 213...Opening and closing door (of supply section)
214, 215...Air intake (of supply section)
219...Handle 221...Top cover 222...Shelf 223...Opening and closing door (for main combustion chamber)
228...Supply section-main combustion chamber opening 239...Chimney connection section <hereinafter, 281 to 288G are elements of the pellet box>
281...Storage section 281S...Storage amount confirmation window 282...Pellet amount adjustment means 283...Combustion section 284...Air supply port 285...Main combustion section 285G...Lattice structure (fire grate) forming the main combustion section
286... Auxiliary combustion section 286G... Lattice structure (fired lattice) forming the auxiliary combustion section
287: Bottom of auxiliary combustion section 288: Air supply guide structure 288G: Air supply guide structure lattice (air flow lattice)
F: Air flow P: Pellet fuel, refrigerated fuel W: Fuel for natural combustion (firewood, etc.)

Claims (12)

A supply unit that supplies fuel for spontaneous combustion and supplies air;
a main combustion chamber communicating with the supply section and in which combustion takes place;
and an exhaust section through which the airflow from the main combustion chamber is finally exhausted,
A main body airflow guide chamber is provided between the main body combustion chamber and the exhaust section to extend the flow path of the airflow,
The main airflow induction chamber has a front-flow side vent between the main combustion chamber and the upper part.
A downstream side vent is provided between the lower portion and the exhaust portion,
The main combustion chamber is provided with a window through which the internal flame can be seen ,
The supply unit is formed so that a pellet box, which is an attachment for storing, supplying, and burning pellet fuel, can be detachably attached to the supply unit.
The pellet box comprises a storage section for storing pellet fuel, a pellet amount adjusting means for adjusting the amount of pellet fuel supplied by natural drop from the storage section, and a combustion section for combusting the supplied pellet fuel,
The combustion section of the pellet box comprises an air inlet, a main combustion section in which the pellet fuel is combusted by air supplied from the air inlet, and a sub-combustion section provided on the side of the main combustion section;
The auxiliary combustion section is provided with a lattice structure, i.e., a charcoal grate, having a narrower spacing than the fire grate, which is a lattice structure constituting the main combustion section, for storing pellet fuel, i.e., charcoal fuel, which has been reduced in size by combustion and passed through the side of the fire grate,
The pellet box is configured so that the main combustion section communicates with the main combustion chamber when the pellet box is installed in the natural combustion stove.
A natural combustion stove. The natural combustion stove of claim 1, characterized in that the main body airflow induction chamber is provided back-to-back with the rear surface of the main body combustion chamber, and the exhaust section is provided in contact with the main body airflow induction chamber as well as in contact with the main body combustion chamber and the supply section. 3. A natural combustion stove as claimed in claim 1 or 2 , characterized in that the pellet box is attached as a detachable attachment. 4. The natural combustion stove according to claim 1, 2 or 3, wherein the auxiliary combustion section is formed with an incline toward the main combustion section. 5. The natural combustion stove according to claim 4 , wherein the auxiliary combustion section and the ash receiving section below it are separated by a bottom of the auxiliary combustion section. A natural combustion stove as described in any one of claims 1, 2, 3, 4, or 5, characterized in that the combustion section is provided with an air intake guide structure that forms a flow path that narrows the air intake from the air intake port and introduces it directly into the main combustion chamber. The natural combustion stove of claim 6, characterized in that the air intake guide structure is arranged to guide the air intake so that it hits the window installation surface of the main combustion chamber when the pellet box is attached to the natural combustion stove. 8. A natural combustion stove as claimed in claim 1, 2, 3, 4, 5 , 6 or 7, characterized in that the bottom of the air intake is the fire grate. A spontaneous combustion stove as described in any one of claims 1, 2, 3, 4, 5, 6, 7, and 8, characterized in that it is provided with at least one of the following <C1> and <C2>.
<C1> An oven provided below the main combustion chamber <C2> A top cover provided on the top surface of the main combustion chamber A removable pellet box that can be used with the spontaneous combustion stove according to any one of claims 1, 2, 3, 4, 5, 6, 7, 8, and 9 , said pellet box being an attachment for storing, supplying, and burning pellet fuel;
a storage section for storing pellet fuel;
a pellet amount adjusting means for adjusting the amount of pellet fuel supplied by gravity falling from the storage portion;
and a combustion section in which the supplied pellet fuel is combusted ,
The combustion section of the pellet box comprises an air inlet, a main combustion section in which the pellet fuel is combusted by air supplied from the air inlet, and a sub-combustion section provided on the side of the main combustion section;
The auxiliary combustion section is provided with a lattice structure, i.e., a charcoal grate, having a narrower spacing than the fire grate, which is a lattice structure constituting the main combustion section, for storing pellet fuel, i.e., charcoal fuel, which has been reduced in size by combustion and passed through the side of the fire grate,
The pellet box is configured so that the main combustion section communicates with the main combustion chamber when the pellet box is installed in the natural combustion stove.
A pellet box comprising: A method for using a spontaneous combustion stove according to any one of claims 1, 2, 3, 4, 5, 6 , 7, 8 and 9 as a pellet stove, comprising:
The pellet box is attached to the natural combustion stove,
The pellet fuel is ignited by any of the following <F1>, <F2>, or <F3>.
This method of using a natural combustion stove is characterized in that combustion continues at a specified temperature range without any power or electricity thereafter.
<F1> Spontaneous ignition caused by a fire caused by the preceding combustion of firewood fuel. <F2> Ignition by an ignition means in a state in which the spontaneous combustion stove is being preheated by the combustion of firewood fuel. <F3> Ignition by an ignition means in a state in which the spontaneous combustion stove is being preheated by the ignition means. 12. The method for using a spontaneous combustion stove according to claim 11 , wherein the temperature range is 300±15° C., and the temperature range is reached within 15 minutes after ignition.