|
(11) | EP 2 444 725 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||||||
| (54) | Solid-fuel heating apparatus |
| (57) The present invention refers to a heating apparatus, such as for example a stove,
a fireplace or similar device, suitable to be supplied with solid fuel. A solid-fuel heating apparatus according to the invention includes combustion air intake means (3) in fluid communication with a combustion chamber (2) and an adjusting device (15) for controlling the flow rate of the combustion air drawn into the apparatus. The apparatus is characterized in that said adjusting device (15) includes a header (16) provided with a plurality of openings (18, 19, 20) and a movable element (22) provided to at least partly obstruct said plurality of openings (18, 19, 20), said movable element (22) being controlled by a system (34) for converting a rotational movement into a linear movement comprising a rack (25) and a pinion (26). |
[0001] The present invention refers to a heating apparatus, such as for example a stove, a fireplace or similar device, suitable to be fed with solid fuel such as, for example, pellets, or particles of pressed wood residues, firewood, coal or other flammable material in the form of fragments or blocks. The solid-fuel heating apparatus according to the invention is provided with an improved combustion-air adjusting system.
[0002] Solid-fuel heating apparatuses are known from the prior art, such as for example wood-burning stoves, heating fireplaces and heating cookers comprising substantially a combustion chamber wherein a hearth is provided, in which the fuel is positioned manually by a user. The combustion air is supplied to the combustion chamber through a conduit communicating with the external environment.
[0003] It is well known that in the different phases of operation of a solid-fuel heating apparatus the quantity of combustion air necessary for a proper fuel combustion varies from phase to phase. In fact, a substantial quantity of air is necessary in the ignition phase of a solid-fuel heating apparatus compared to a situation in which the combustion process is proceeding to generate the rated heating output of the apparatus. Heating apparatuses of known type are provided with a plurality of gate valves arranged within suitable combustion-air diffusing ducts to allow, choke and/or prevent the flow of combustion air, depending on the current phase of operation of the apparatus. Each of said gate valves can be controlled manually by the user, who, whenever he or she wishes to ignite the apparatus, or to simply adjust the size of the heating flame, must adjust the inflow of combustion air by operating on different gate valves at the same time. This procedure, in addition to being particularly complicated and awkward, requires considerable skill and experience in judging if the adjustments made for the different gate valves are really effective or if they lead to an only partial combustion of the solid fuel, with a consequent excessive production of smoke and soot.
[0004] In other embodiments of known type, the gate valves are controlled through automatic processes, but in this case too the devices for operating the different gate valves as well as the means used to coordinate their movements are rather complicated and difficult to make and assemble.
[0005] One purpose of the present invention is to provide a solid-fuel heating apparatus that overcomes the drawbacks and disadvantages of prior art heating apparatuses.
[0006] In the scope of the above purpose, one objective of the present invention is to achieve a solid-fuel, for example a biomass-burning, heating apparatus provided with a combustion-air adjusting device that is more efficient than the hitherto known adjusting devices.
[0007] Another objective of the invention is to provide a reliable and easy-to-use solid-fuel heating apparatus.
[0008] A further objective of the present invention is to achieve a solid-fuel heating apparatus that allows an efficient and fine adjustment of the intensity of the combustion flame, wherein said adjustment is simple to carry out by the user.
[0009] One still further objective of the present invention is to provide a solid-fuel heating apparatus that improves the combustion of the solid fuel, reducing the quantity of unburnt fuel and drastically decreasing the emissions of dust and polluting substances.
[0010] One not least important objective of the present invention is to achieve a solid-fuel apparatus in which the adjustment of the inflow of combustion air can be carried out with a minimum number of control steps, in particular a combustion-starting step and a second step to adjust the size of the heating flame of the apparatus.
[0011] One still other objective of the present invention is to provide a solid-fuel heating apparatus in which said control steps can be carried out through a single actuating device.
[0012] The above task and objectives are achieved by a solid-fuel heating apparatus having the characteristics set forth in the accompanying claim 1. Characteristics and advantages of the invention will become evident from the description which follows, by way of non-limiting example, with reference to the enclosed drawings, wherein:
- Figure 1 illustrates a cross-sectional side view of a solid-fuel heating apparatus according to the invention;
- Figure 2 illustrates a perspective exploded view of a device for adjusting the flow rate of combustion air fed into the apparatus of Figure 1;
- Figures 3A, 3B, 3C illustrate, in a plan view, the adjusting device of Figure 2 in three different operating positions.
[0013] With reference to Figure 1, a heating apparatus suitable to be fed solid fuel according to the invention is shown by way of example in the form of a wood-burning stove. Naturally, the innovative concepts of the present invention can also be applied, on the basis of the description which follows, to other types of solid-fuel heating apparatuses, such as for example pellet stoves, heating fireplaces or similar devices. The apparatus according to the invention includes a holding body 1, within which is provided a combustion chamber 2 which receives the solid fuel to be burned. The apparatus includes combustion air feeding means 3 in the form of aeraulic conveying means 4, 5, 6 provided to distribute the combustion air in different regions of the apparatus in order to improve the combustion of the solid fuel and/or avoid the formation of buildups of unburnt fuel in parts of the apparatus that are difficult for a flame to reach, such as the corners of the combustion chamber 2, the glazed door 7 that provides access to the latter, and so on. If necessary, the combustion air intake means 3 may include fans for forced air draft.
[0014] The combustion air drawn in from the atmosphere through an inlet 8, flowing through the combustion air intake means 3, is expelled through nozzles 9. Beneath the combustion chamber 2, and separated by a grate 10, is an ash collecting space 11. Suitable insulation elements 13 are provided to hold the heat generated by combustion within the body 1 of the solid-fuel heating apparatus. A combustion gas exhaust conduit 14 is provided in the upper portion of the holding body 1.
[0015] To adjust the flow rate of the combustion air drawn in from the environment surrounding the apparatus, an adjusting device 15 is installed between the inlet 8 and the combustion air feeding means 3. The combustion air flow rate adjusting device 15, as can be seen in Figure 2, includes a header 16 that is preferably connected to the inlet 8 or made integral to the same. The header 16 is provided with a plurality of openings 18, 19, 20 which, when the adjusting device 15 is mounted on the solid-fuel heating apparatus, are arranged in fluid communication with the aeraulic conveying means 4, 5, 6 as can be seen in Figure 1. The header 16 preferably includes a box-like body 24 and a lid 17 removably mounted through removable fastening means, as for example screws 21, on the box-like body 24. The openings 18, 19, 20 are formed on the lid 17 that also includes relief elements 32 that form sliding guides, as will be described later.
[0016] A movable element 22, preferably in the shape of a plate 23, is slidably mounted on the lid 17 to completely or partly obstruct the openings 18, 19, 20, thereby determining a choking of the air flow passing through each opening 18, 19 and 20. The coupling between the movable element 22 and the lid 17 brings the relief elements 32 formed on the lid 17 to be received within guide surfaces 35 formed on the movable element 22. On opposite sides of said guide surfaces, the movable element 22 includes edges 36A, 36B formed, respectively, according to an even number and an odd number of steps 38A, 38B. A further pair of openings 37 are formed on the movable element 22.
[0017] A system 34 for converting a rotating movement into a linear movement is provided to cause the movement of the movable element 22. The system 34 includes a rack 25 and a pinion 26, engaging said rack 25, mounted on a rotating shaft 27 and accessible from outside the holding body 1 to allow it to be controlled manually through an extension 28 and a knob 29 (Figure 1). Naturally, the rotating shaft 27 can also be power driven by applying a motor of known type, for example an electric motor. Advantageously, the rack 25 is formed on the movable element 22 by means of a plurality of through slits 30 arranged parallel to each other at a pitch corresponding to the pitch of the teeth on the pinion 26, so as to allow the meshing thereof. The rotating arm 27 is rotatably mounted on the lid 17 by means of through holes 33 present on the latter. The pinion 26 is housed at least partially inside the box-like body 24 of the header 16.
[0018] A gasket 31, made of heat-resistant material, is placed on the movable element 22 so that the latter is sandwiched between the gasket 31 and the lid 17.
[0019] In Figures 3A, 3B, 3C is illustrated, in a plan view, the device 15 for adjusting the combustion air in three different operating positions. With reference to Figure 3A, the movable element 22 is in a position in which the openings 18, 19 and 20 of the header are left uncovered in a substantially complete manner. In this position, in which the movable element 22 is located completely on the left in Figure 3A, the flow of combustion air inside the solid-fuel heating apparatus is at its maximum, as is necessary during the first solid-fuel combustion starting phase.
[0020] In Figure 3B, the movable element 22 is shown as it was moved toward the right from the position shown in Figure 3A through a rotation of the rotating shaft 27 which activates the system 34 comprising the coupling of the rack 25 and the pinion 26. In this position, the opening 19 is obstructed for most of its extent by the step 38A of the movable element 22. The opening 19 is not completely obstructed by the movable element 22, since the slits 30 that intercept the opening 19 and one of the openings 37, as they overlap said opening 19, guarantee a minimum passage of air toward the corresponding aeraulic conveying mean 5 (Figure 1). A step 38 of the movable element 22 overlaps the opening 18, obstructing it only partially and leaving the greater part of its extent available for the passage of combustion air. The configuration of the openings 18, 19 and 20 shown in Figure 3B is typical of the situation in which the solid-fuel heating apparatus operates when providing its nominal heating power.
[0021] In Figure 3C, the movable element 22 is shown as it was moved father toward the right than the position shown in Figure 3B through a further rotation of the rotating shaft 27, or an activation of the system 34 for converting the rotational movement of the shaft 27, and consequently the pinion 26, into a linear movement of the rack 25 made integral with the movable element 22. In this position, the degree of obstruction of the opening 19 remains identical to the one described with reference to Figure 3B, while the opening 18 is completely closed by a step 38B of the movable element 22, thus preventing the passage of air through the opening 18. The configuration of the openings 18, 19 and 20 shown in Figure 3C corresponds to an operating condition of the solid-fuel heating apparatus in which combustion is slowed to a minimum without extinguishing it.
[0022] During the passage from the operating condition with nominal power shown in Figure 3B to the operating condition with minimum combustion shown in Figure 3C, the movement of the movable element 22 causes a progressive increase of the degree of obstruction of the opening 18 while the degree of obstruction of the opening 19 remains constant. Advantageously, therefore, with a single movement of the movable element 22 it is possible to vary the flow rates of the air flowing through a plurality of openings 18, 19, and consequently to feed with different flow rates different regions of the solid-fuel heating apparatus, thus achieving an improvement in the combustion efficiency of the solid fuel and thereby a generally improved performance of the apparatus.
[0023] In comparing Figures 3A, 3B and 3C, it can be seen that the opening 20 is never obstructed by the movable element 22. This is due to the fact that the opening 20 feeds an aeraulic conduit 6 with air that is directed toward the glass door 7 of the apparatus to remove any built-up residues resulting from combustion. The openings 18 and 19, communicating respectively with the aeraulic conduits 4 and 5, are dedicated to feeding the combustion chamber 2 with air, respectively for the operation of the apparatus in steady-state condition, and for the first ignition of the solid fuel.
[0024] It was ascertained that the invention achieved the preset objective and purposes, having realized a solid-fuel heating apparatus in which the combustion air adjusting device makes it possible to advantageously improve the combustion of the solid fuel, thus increasing the efficiency of the apparatus and decreasing at the same time the emissions of dust and polluting substances. The adjusting device can be activated through a manual or a power-driven control means, thereby simplifying the process for its operation and control.
1. Heating apparatus suitable to be fed with solid fuel comprising combustion air intake
means (3) in fluid communication with a combustion chamber (2) and an adjusting device
(15) for controlling the flow rate of the combustion air intake into said apparatus,
characterized in that said adjusting device (15) includes a header (16) provided with a plurality of openings
(18, 19, 20) and a movable element (22) provided to obstruct at least partially said
plurality of openings (18, 19, 20), said movable element (22) being driven by a system
(34) for converting a rotating movement into a linear movement comprising a rack (25)
and a pinion (26).
2. Heating apparatus according to claim 1, wherein the rack (25) is formed on said movable
element (22) by a plurality of slits (30).
3. Heating apparatus according to claim 2, wherein said slits (30) intercept one opening
(19) of said plurality of openings (18, 19, 20).
4. Heating apparatus according to any one of the previous claims, wherein said movable
element (22) is configured to move between two positions, thus causing a change in
the degree of obstruction of a first opening (18) and keeping constant the degree
of obstruction of a second opening (19).
5. Heating apparatus according to any one of the previous claims, wherein said movable
element (22) includes two edges (36A, 36B), one of them shaped with an even number
of steps (38A) and the other shaped with an odd number of steps (38B).
6. Heating apparatus according to claim 5, wherein said edges (36A, 36B) are disposed
on opposite sides of guide surfaces (35).
7. Heating apparatus according to any one of the previous claims, wherein said movable
element (22) consists of a plate (23).
8. Heating apparatus according to any one of the previous claims, wherein said header
(16) comprises a box-like body (24) and a lid (17) on which is arranged said plurality
of openings (18, 19, 20).
9. Heating apparatus according to claim 8, wherein said movable element (22) is interposed
between a gasket (31) and said lid (17).
10. Heating apparatus according to any one of the previous claims, wherein said plurality
of openings (18, 19, 20) is in fluid communication with a corresponding plurality
of aeraulic conduits (4, 5, 6).
11. Heating apparatus according to any one of the previous claims, wherein said motion
conversion system (34) is controlled manually through a knob.
12. Heating apparatus according to any one of the previous claims from 1 to 10, wherein
said conversion system (34) is driven by a motor.