EP0867662A1 - Combustion control system for fireplace with double fire - Google Patents

Abstract

The combustion regulator is for a fireplace with a double hearth which can be closed. It is connected to an outlet duct (10) and is enclosed by a series of refractory panels (14,15). Its upper wall is made in two separate sections (4,5) which can be moved relative to one another on guides. The sections can be easily adjusted to regulate the size of an additional air intake gap between them. The rear panel of the fireplace has an aperture (16) to allow the direct passage of combustion gases into the outlet duct in proportion to the intake of air between the separable sections of the upper wall. The upper wall sections are made in the form of sliding panels and the guides are in the form of ledges round a central aperture.

Description

The invention relates to bifocals and more specifically relates to a device for adjusting combustion and re-ignition of smoke for a improved efficiency and reduced gas unburnt.

A chimney is said to be double hearth when it allows both to provide an open and visible fire, but also to have a closed or partially closed combustion vessel closed operating like a traditional wood stove.

We know in particular by FR-A 2 597 197 in the name of Applicant a chimney type combustion vessel, which has two levels of hearths: a closed lower hearth, closed at its upper part by two shutters likely to move relative to each other, and a focus open upper whose bottom is formed by these flaps which form the basis of this upper hearth. The recipient forming the lower hearth is surrounded on the bottom and lateral sides of at least one traffic envelope air which heats up on contact with said walls container.

In this type of appliance the fumes from the lower hearth must therefore circulate first along the side walls container before reaching the rear wall and exhaust duct, and this precisely to allow a good heat exchange with the air in the external envelope. To channel this smoke to the side, you can insert between the wall of the container and the air envelope, a first closed envelope communicating with the combustion through a plurality of orifices.

More simply, we equip the interior of the fireplace with combustion itself of vertical refractory plates slightly apart from the walls of the container. So there is a bottom plate and two side plates that extend over the entire height of the container and which delimit, internally the combustion chamber proper of the indoor fireplace, and outside a corridor for the passage of smoke between said plates and the walls sides of the container. Of course the side plates do not fully extend to the front of the combustion vessel. So the fumes emitted are they led to bypass these front side plates from the front to go back, on both sides, then converge towards the central part of the rear wall and the exhaust duct.

During this extended journey, the fumes and gases from combustion give up the maximum calories to the circulating air in the outer envelope. Therefore, at the entrance of the drain there is a significant drop in the smoke temperature. In addition there are gases unburnt containing carbon monoxide. It's a disadvantage that it would be interesting to eliminate or at all less to mitigate, both for increasing the yield of the device only for safety and pollution.

The Applicant endeavored to find a solution to this problem, which allows, under certain conditions to operation, a re-ignition of the fumes at the base of the exhaust duct, and consequently decrease the emission of unburnt gases and the concentration of carbon at this lower hearth.

The main object of the invention is therefore a device regulating combustion in a double hearth fireplace comprising a combustion chamber which can be closed, connected to a discharge pipe and delimited by a plurality of refractory plates, and whose walls outside are surrounded by an envelope intended for air circulation, said chamber being closed by at minus a removable upper wall which forms the base a second open hearth, a device according to which the wall removable upper consists of two elements separable with guide means allowing their easy spacing from one another for adjustment of the additional combustion air induction slot in the combustion chamber, and according to which an opening is provided in the bottom refractory plate for the passage direct combustion gases to the exhaust pipe in function of the introduction of combustion air between the separable elements.

Advantageously, the separable elements are sliding plates positioned on an angle iron surrounding the central opening of the hearth plate, and below its upper side, to put the hearth plate and the plates sliding at the same level as the masonry elements of the fireplace.

Similarly, an inclined panel is provided along the orifice center of the hearth plate, on the front side of the combustion.

The spacing of the plates is prepositioned by grooves and a bar secured to the front plate.

According to another particular characteristic of the invention, the section of the direct passage opening of products of combustion to the exhaust pipe is about one tenth of the normal cross section of products of combustion by the sides of the appliance.

Figure 1, une vue générale en perspective de la cheminée à double foyer

Figure 2, une autre vue en perspective de la cheminée, vue sous un autre angle, avec les plaques supérieures ouvertes

Figure 3, une vue en coupe verticale du récipient de combustion.

Figure 4, une vue partielle en coupe verticale, à plus grande échelle, de la partie supérieure du récipient de combustion.

Other particular characteristics and advantages of the invention will emerge from the description which follows of a nonlimiting example of embodiment in which reference is made to the appended drawings which represent:

Figure 1, a general perspective view of the double hearth fireplace

Figure 2, another perspective view of the chimney, seen from another angle, with the upper plates open

Figure 3, a vertical sectional view of the combustion vessel.

Figure 4, a partial view in vertical section, on a larger scale, of the upper part of the combustion vessel.

It can be seen in FIGS. 1 and 2 that the container of combustion 1 has a closed enclosure 2 which constitutes the combustion chamber of the lower hearth, the face of which upper 3 is pierced with an opening closed by two separable elements which in this case are plates sliding 4 and 5. These plates form the basis of a second upper fireplace which, depending on their opening - can communicate with the lower fireplace.

As an alternative embodiment, the plates could be replaced by any tilting or interlocking system.

Chamber 2 is closed by side walls 6, a front wall 7 and a rear wall 8. The face upper 3 is a hearth plate which integrates advantageously flush with the masonry elements 9 as is see more clearly in Figure 2. A conduit 10 smoke evacuation which communicates with the bottom of the combustion chamber 2, is arranged along the wall rear 8.

All around said chamber delimited by its walls vertical (6, 7, 8), a peripheral envelope is mounted 11 intended for the circulation of air which will heat up contact of the walls of the lower hearth. This air enters the casing by a conduit 12 near the front face from the combustion vessel and emerges from it through a conduit 13 to proximity to the rear face and the opposite side.

Inside the combustion chamber 2, there is placed vertical refractory plates, namely two side refractory plates 14 parallel to the walls sides 6 of the hearth, and a bottom refractory plate 15 parallel to the rear wall 8. This bottom plate is advantageously carried out in two independent parts (15a, 15b) juxtaposed to facilitate mounting like this appears in Figure 1. These refractory plates are slightly away from the sides of the container, and the plates side 14 do not extend to the front wall 7 of the container. We understand that in this way the fumes and products of combustion emitted in chamber 2 are caused to bypass the plates 14 then to start backwards, in the direction of the exhaust duct 10, in the corridors as well realized. Finally, in front of this conduit, there is provided a circular opening 16 in the bottom refractory plate 15, substantially at mid-height. This opening whose role will appear later, has a particular diameter in depending on the dimensions of the fireplace.

Referring also to Figures 3 and 4, we note that the sliding plates 4 and 5 are positioned on an angle iron 17 surrounding the central orifice of the hearth plate 3. These angles serving as support are below the upper face of the hearth plate. So the sliding plates are level with the hearth plate.

The sliding plate 5 is easily released towards the front thanks to an inclined panel 18 provided along the orifice center of the hearth plate, on the front side of the combustion, the side angles acting as slides for plate 5. Thus the angle 17 and the pan inclined 18 together constitute the means for guiding the plates (4, 5). We can also, without completely clearing the plate 5, move it more or less from plate 4 to leave a more or less wide slit between the two. For facilitate a more rigorous positioning of this spacing between the two plates, we advantageously equip the front of the plate 5 of a bar 19 which can be placed in one of several grooves 20 spaced from one another by number of steps which correspond to a few possible preset spacing of the two plates.

We know that this type of double hearth fireplace can operate in several ways. It works like a stove closed when plates 4 and 5 completely block the orifice of the hearth plate 3.

The fire develops inside enclosure 2, most of the combustion products bypassing refractory plates (14, 15) up to the exhaust duct 10. Little combustion gas passes directly from the fireplace to the conduit through the opening 16; the temperature is practically the same on both sides of the hole.

The chimney can also function as a chimney classic, the fire being created above the hearth plate. Alternatively, if the plates (4, 5) are ajar the chimney will work with normal draw and reverse draw to the bottom.

The invention provides an additional possibility for closed stove operation, taking advantage of the opening 16 provided in the refractory plate 15 for the direct passage of combustion products to the flue exhaust, and additional air induction oxidizer through the slot created between the two plates (4, 5) when we separate them from each other, to optimize the combustion as a function of the vacuum in the duct evacuation.

If we slightly move plate 5 away from plate 4 (first positioning notch), the small opening formed between the two will relaunch the fire in room 2; a small part of the combustion gases and flames will pass through hole 16 directly to conduit 10. If the spacing is greater, the air intake being more important, this direct passage is further accentuated and causes the smoke to reignite at the base of the duct. Thus is eliminated or at least attenuated the emission of gas toxic, while improving the yield of the device. The combustion gas flow diagram by arrows in Figure 3, illustrates their journey well normal and their "short" path through hole 16.

For good re-ignition efficiency, the orifice 16 must not be too small in diameter, in which case it would be ineffective. It must not have too large a diameter which would cause too much direct passage of combustion gas at the expense of a good heat exchange with the air of the peripheral envelope 11. Advantageously the diameter of the opening represents a gas passage section of the order of 13 cm ² . For a volume of chamber 2 of the order of 65 liters, the section of the lateral passages for the combustion products bypassing the side refractory plates 14 is of the order of 130 cm ² . Thus, the section of the direct passage opening 16 of the combustion products towards the evacuation duct 10 is approximately one tenth of the normal section of passage of the combustion products through the sides of the appliance.

Depending on the liveliness of the fire carried out in the room 2, the user will move the plate 5 more or less to activate the combustion and obtain a re-ignition of the fumes.

Such a system does not exclude operation in double hearth, i.e. a fire in bedroom 2 and a other above the hearth plate 3.

Thanks to the inclined face 18, the plate 5 is released easily out of the hearth plate 3, for example for the loading the wood into the combustion chamber (Figure 2). Note that the two plates 4 and 5, in position closed or ajar are at the same level as the plate hearth 3 and that the masonry elements 9 which presents a great advantage in terms of aesthetics.

Claims (5)

Device for regulating combustion in a double hearth fireplace with a combustion chamber can be closed, connected to a discharge pipe and delimited by a plurality of refractory plates, and of which the outer walls are surrounded by an envelope intended for air circulation, said chamber being closed by at least one removable upper wall which constitutes the base of a second open hearth characterized in that that the removable upper wall consists of two separable elements (4, 5) having guide means (17, 18) authorizing their easy spacing one relative to the other for adjusting the induction slot additional combustion air in the combustion chamber (2), and in that an opening (16) is provided in the bottom refractory plate (15) for the direct passage of combustion gases to the exhaust pipe (10) in function of the introduction of combustion air between the separable elements. Adjustment device according to claim 1, characterized in that the separable elements are sliding plates (4, 5), positioned on an angle (17) surrounding the central orifice of the hearth plate (3), and below its upper face, to put the plate fireplace and sliding plates at the same level as the masonry elements (9) of the chimney. Adjustment device according to claim 2, characterized in that an inclined face (18) is provided along from the central opening of the stove plate (3), on the front side of the combustion chamber (2). Adjustment device according to claim 2, characterized in that the spacing of the plates (4, 5) is prepositioned by grooves (20) and a bar (19) secured to the front plate (5). Adjustment device according to claim 1, characterized in that the section of the opening (16) of direct passage of combustion products to the flue discharge (10) is approximately one-tenth of the cross-section normal passage of combustion products from the sides of the device.

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