EP0678184A1

EP0678184A1 - Solid fuel heating devices and components for them

Info

Publication number: EP0678184A1
Application number: EP94904223A
Authority: EP
Inventors: Jonathan Greenall
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-01-09
Filing date: 1994-01-05
Publication date: 1995-10-25
Anticipated expiration: 2014-01-05
Also published as: DK0678184T3; ES2124387T3; WO1994016271A1; GB9400058D0; GB2274162A; DE69412999D1; GB2274162B; EP0678184B1; DE69412999T2; GB9300364D0

Abstract

A stove has a baffle deflector member (10) which is hollow and provides an air supply (13) to the fire box (1) of the stove. The deflector member (10) is adapted to be removed from the fire box (1) easily for repair or replacement. The deflector member has a pattern of air outlet holes (13) around its peripheral edges, and a line (19) of air holes across its middle region. The holes across its middle region are formed and then the metal of the deflector member bent on their line. This gives those holes a non-round tapering cross section which is believed to give an enhanced mixing effect to the stream of air coming from those holes. The large number of air outlets over a large area of the fire box promotes full mixing of the fire box air, and full combustion of the fuel.

Description

SOLID FUEL HEATING DEVICES AND COMPONENTS

FOR THEM

This invention relates to solid fuel heating devices, such as stoves, and a component for them.

Solid fuel heating stoves have been in common use for many hundreds of years. A common arrangement for a stove is to have a primary air control, and also a secondary air control, which is adjustable to control the burn speed of the appliance.

For some time now there has been a desire to improve the emissions of fires so as not to pollute the air too much. There have been many attempts worldwide to improve the combustion efficiency of stoves, thereby reducing the smoke emitted by them. Conventional air controls control the burning speed of the fire, however restricting air to the fire (in order to slow down its burning) causes air starvation and prevents full combustion. I believe that it is important for the fire box temperature to be high in order to achieve fuller combustion, and reduce smoke. Preheating air flow to the fire has a considerable advantage in this respect.^' Many devices have been developed to pre-heat combustion air and then pass it to parts of the fire box.

It is known to have a baffle, or deflector, plate in the region of the top of the fire box which serves to deflect rising air and prevent it from flowing directly to the exhaust outlet from the stove. Such a deflector plate may well cause rising air to circulate back within the fire box. This circulation keeps the air, and its associated smoke particles, in the hot region of the fire box for longer and allows more of the smoke to be burned off. Furthermore, mixing the smoke laden air more thoroughly also encourages fuller burning.

One long established problem is that solid fuel heating devices have a hot fire and it is guite common for the corrosive products of combustion to attack the interior of the fire. As a general rule a hotter fire will produce cleaner combustion than a cooler fire. However, the result of having a hot fire is that the heating device may have a shorter operational lifetime.

An aim of the present invention is to provide a new baffle or deflector member.

According to a first aspect of the invention I provide a heating device having a fire box and a deflector member adapted to deflect air rising in the fire box, the deflector member providing an air supply to the fire box and being adapted to be replaced.

Thus the addition of an air supply to the fire box by the deflector member increases the degree of combustion, and the fact that the deflector member is adapted to be replaced easily means that the disadvantages of a hot fire corroding components of the stove, or other appliance, can be ameliorated.

The deflector member preferably has an air outlet aperture which is non-round. The air outlet aperture is preferably generally elliptical.

The deflector member is preferably a separate component.

The deflector member preferably has at least one inlet port which registers with an inlet aperture in a wall of the heating appliance. The deflector member preferably has an air inlet projection which defines an air inlet passage and which extends to or beyond the external wall of the fire box. The air inlet projection preferably extends through the wall of the appliance and beyond.

Of course, the deflector member may have a female air inlet connector and the wall of the appliance a male inlet air connector.

The deflector member preferably provides an uncontrolled air supply to the fire box. There may be one, or two, or further air supplies in addition to the air supply of the deflector member.

The deflector member preferably has a generally downwardly facing surface provided with an air outlet. The surface is preferably provided with a plurality of air outlets. There may be a line of air outlets adjacent a peripheral edge of the deflector member. There may be lines of air outlets adjacent two, three, or four edges of the deflector member. A line of air outlets at the front lip of the deflector member is believed to encourage tumbling circulation of air in the fire box. This encourages more complete combustion.

There may be one or more air outlets in the downwardly facing plan area of the deflector. There may be a line of air outlets extending in the plan area of the deflector, but not adjacent an edge. The line may extend across the deflector member.

By having an air outlet (or outlets) in the main plan area of the deflector I cause air to be directed into the body of the fire box. I believe that this may improve combustion.

There may be two downwardly facing surfaces on the deflector. Each surface may have an air outlet, or outlets. An air outlet, or outlets, may be provided at the angle where the two surfaces meet. This is believed to encourage full combustion.

According to a second aspect of the invention I provide a deflector member having air supply means and being adapted to be readily replaced.

According to a third aspect of the invention I provide a deflector member having an air supply inlet and a plurality of air supply outlets adapted to supply air to the fire box of a heating appliance in which the deflector member is adapted to be installed.

The deflector member preferably has an air chamber or passage and a plurality of air outlets from the air chamber or passage. The chamber preferably defines a substantial part of the volume of the deflector member, and preferably substantially all of the volume of the deflector member. There is preferably a big pre-heating chamber in the deflector member provided with many air outlet holes.

At least one or more of the air outlets may be non-round. There may be at least five outlets and preferably at least ten outlets.

According to a fourth aspect of the invention I provide a deflector member adapted to be installed at an upper region of a fire box, the deflector member having an air inlet, and an air outlet aperture, and a fold line about which it is folded, the air outlet being near or on the fold line.

According to a fifth aspect of the invention I provide an air supply to a fire box of a heating appliance comprising a generally oval, cylindrical, or non-round air outlet aperture.

This is believed to alter the effect of air coming from the air outlet.

According to a sixth aspect of the invention I provide an air supply to a fire box of a heating appliance having an air outlet aperture which has a varying cross section.

This is believed to alter the effect of air from the air outlet.

Preferably the air outlet narrows in cross-sectional area in the direction towards the interior of the fire box.

According to a seventh aspect of the invention I provide a deflector member adapted to be installed in a heating appliance having a downwardly projecting lip at or towards its forward end.

This is believed to increase the mixing of air in the fire box.

According to an eighth aspect of the invention the invention comprises a method of reducing the maintenance costs of operating a heating appliance which is provided with a deflector member which has an air supply, the method comprising making the deflector member easily removable.

By providing a deflector member which has an air supply, the air which flows out of the deflector into the fire box may create an air buffer or air dam between the deflector and the air which is already in the fire box. It is believed that such an air buffer keeps some hot fire box gases and combustion products away from the surface of the deflector and thus increases its lifetime. It is also believed that the flow of cooler air through the reflector (relative to the fire .box gases) may also increase the lifetime of the deflector.

In a stove, the method preferably comprises having the deflector plate of such a size that it can be removed through the door of the stove. Alternatively, or additionally, the method may comprise providing the stove with a removable or displaceable top, for example, a lift-off top, such that the deflector member can be removed and replaced easily via the top of the stove.

According to a ninth aspect of the invention the invention comprises a method of manufacturing an air supply component for a heating appliance which has an air outlet, comprising providing a hole in the material of the component, the hole being a proto-air outlet port, and deforming, by for example bending or folding, the component so that the shape of the proto-air outlet is changed.

Preferably the component is deformed at the region of the proto-air outlet. Preferably the proto-air outlet is round, the air outlet after deformation of the component being non-round.

Since making this invention I have become aware of US 4 941 451, which shows a hollow air deflector providing an air inlet to a wood stove. The stove described is very unusual, and its deflector member is difficult to remove or replace.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings of which:-

Figure 1 shows the prior art;

Figure 2 is a schematic cross sectional view of a stove in accordance with the present invention;

Figure 3 is a plan view from the underneath of a deflector member used in the stove of Figure 2;

Figure 4 is a rear view of the deflector member;

Figure 5 is a schematic cross section through the deflector member;

Figure 6 is a perspective view from above and behind of the deflector member; and

Figure 7 shows an air inlet 13 of tapering cross-section provided on the bend line 19 shown in Figure 3.

In order to facilitate the understanding of the present application the reader is directed to read our Patent GB 2 251 302 which shows a stove with some features in common with the present invention. The disclosure and contents of GB 2 251 302 are hereby incorporated into this Application by reference.

Figure 1 shows a multi-fuel stove having a fire box 1, an ash chamber 2 having an ash pan 3, a grate 4, a primary air inlet 5 a door 6, and exhaust outlet 7, and a deflector plate 8 (sometimes called a baffle, or throat plate) resting on refractory bricks 9 which form a back and side walls to the fire box.

Cold air enters through the manually adjustable primary air inlet 5. As the fuel, for example wood, burns the air is consumed, rises and carries smoke with it. The rising air hits the deflector plate 8 and circulates in the fire box before eventually leaving via exhaust outlet 7. This fire can be starved of air by the user if he sets the air inlet 5 incorrectly, and this can cause dirty smoke.

Figure 2 shows a multi-fuel stove which is in many ways similar to that of Figure 1, except that it has an improved deflector plate, referenced 10. The deflector plate 10 is another air supply to the fire box and is perhaps better called a deflector member since it has an internal structure.

The deflector member 10 is perhaps best shown in Figure 6 and comprises a generally rectangular metal box having an internal pre-heating air chamber 11, two air inlets, comprising pipes 12, and a lot of air outlets 13 provided in the lower face of the deflector member 10. The deflector member is made from a bottom sheet 14 welded to an upper sheet 15 at welds 16. Side panels 17 are also welded to the upper and lower sheets. It will be noted that the welds 16 are V-shaped, or rightangled, meetings between the upper ,and lower sheets. The panels of the upper and lower sheets extend generally parallel to each other when the deflector member is assembled.

The upper and lower sheets 14 and 15 each have a fold line 18 and 19. A row of air outlets 13 is provided on the fold line 19.

The holes 13 which are to be on the fold line 19 are made in the sheet metal of the bottom sheet 14, and then the bottom sheet 14 is folded about the fold line 19. This means that the holes on the fold line, which were originally circular, are non-circular after folding. When looked at in plan view they are generally elliptical after folding. Figure 7 shows that another effect of folding on the line of the holes is that they have a generally conical cross section.

The front edge region of the upper sheet 15 projects below the bottom surface of the bottom sheet 14 and provides a depending lip 20.

The inlet pipes 12 each have an associated mounting flange 21 extending from them. Only one of the flanges 21 is shown (in chain dotted outline) in Figure 6, and they can be best seen in Figure 5. The lower sheet 14 also has a flange 22 extending along the rearward part of the deflector member.

The stove has a back wall 23 which has a pair of apertures 24 adapted to receive the pipes 6. In use, as shown in Figure 2, the pipes 6 extend through the apertures 24 and communicate with an external air supply 25. A pair of sealing washer 26, shown in Figure 5, seal the apertures 24 to prevent unwanted air flow through them (they seal in combination with the flange 21). A nut or other clamp member may be provided to act on the protruding part of the pipes of the inlets 12 and clamp the flanges 21 to the inner surface of the back wall 23 (with the washers 26 sealed between the flanges 21 and the wall 23).

External air enters the pre-heating air chamber 11 via the air inlets 12 and is heated there. The air then leaves the chamber 11 via the air outlets 13. This provides an additional, uncontrolled, air supply to the fire. The user cannot shut off the air supply via the deflector plate and so cannot completely starve the fire.

Furthermore, the additional air supply provided by the deflector plate means that there is more fresh air in the fire box and so better combustion takes place. Furthermore, as can be seen from Figure 2, jets of air (referenced 30, 31 and 32) are emitted by the deflector plate and these jets of air encourage turbulent mixing of air in the fire box, rather than a more organised circulation of air which is• what happened in the prior art. The small size of the air inlets 13 mean that there is quite a strong jet of air coming from them.

One feature of particular interest is that the holes 13 on the fold line 19 produce a particularly strong jet of air. These are the deformed holes which have a non-round cross section, and which are generally conically tapered. We have found that this produces a spiralling, rifling effect, and the jet of air from these holes extends some considerable distance into the fire box and causes very disorganised, chaotic burning. Indeed, the burning with the present invention could almost be said to be violent. The independent air supply from the deflector plate mixes the air in the fire box and encourages a cleaner, and hotter burn.

The lip 20, also causes additional turbulence and additional mixing. It may encourage the tumbling rolling of a body of air in the fire box, or it may not.

The deflector member 10 is especially adapted to be easily removed and replaced. The member simply rests on the fire bricks 9 on the back wall, and the fire bricks of side walls (not shown) . The deflector, baffle, plate is of such a size that it can be removed through the door of the stove. Alternatively, or additionally, the stove may have a lift-off top which can be removed to allow easy maintenance or replacement of the deflector member. There are no external fixings attaching the deflector plate to the stove other than the pipes 12 which extend through the back wall of the stove.

The fact that the deflector plate is easily removed for maintenance or replacement is an advantage because it will probably wear out and will need to be replaced during the life of the stove.

The holes down the side regions of the deflector member disturb the air in the side regions of the stove. This air is usually rather more stagnant than that of the centre of the stove. Similarly, the air holes at the rear region of the deflector member disturb the air at the rear of the fire box. Thus air flows from the chamber 11 through the air outlets 13 and mixes with the combustion gases high in the fire box promoting thorough combustion and reducing smoke emissions. It will be appreciated that it is a simple matter to fit the deflector member of the present invention to an existing stove, such as that shown in Figure 1. All that will be required is for the holes 24 to be drilled in the stove and the old deflector plate replaced by the new deflector member 10. This is a simple operation. It will also be appreciated that the deflector member is a self contained unit. This facilitates maintenance and installation.

We also envisage manufacturing stoves with the holes 24 already in them and giving the customer the choice of whether to have the new deflector member, or whether to have the old conventional deflector member (in which case the holes 24 will be plugged). We may even sell a kit comprising a stove and a new deflector member, and possibly an old, conventional, deflector member. The kit may have plugs for the holes which can receive the pipes 12.

It will be appreciated that the air inlets 13 need not be roughly circular, but could be square, or slots or any shape.

Since the chamber 11 is of very much larger volume than the size of the holes 13 the air has sufficient time to be pre-heated to a high temperature. The fact that there are a large number of holes 13 means that the air in the fire box is well supplied with additional air and aggetated over a substantial area. Having holes in the plan area of the undersurface of the deflector member means that the air centre region of the fire box is disturbed, mixed, in the jets of air.

The stove may have an airwash system providing a flow of pre-heated air over the internal face of the door of the stove. The airwash system may be as described in GB 2 251 302.

It could, of course, be possible to have the air supply to the deflector member coming from the surrounding room. Although the air flow from the deflector member is described as being independent of the air controls on the stove there may be occasions where it is desirable to have this air supply controllable by the user, or connected to other air controls of the stove. It may have its own air control, or it may be operated by an air control that also controls another air supply (for example the main updraft air supply, or an airwash air supply) .

It is believed that by having a large member of air outlet holes spread out over the area of the fire box there is fuller mixing of the fire box air due to the effects of air streams from the deflector member air outlets. This results in fuller combustion and less pollution by partially combusted emissions.

Claims

1. A heating device having a fire box (1) and a deflector or baffle member (10) adapted to deflect air rising in the fire box, the deflector member (10) providing an air supply (30, 31) to the fire box and being adapted to be replaced.

2. A heating device according to claim 1, in which the deflector member (10) is a separate component.

3. A heating device according to claim 1 or claim 2, in which the deflector member has at least one inlet port (12) which registers with an inlet aperture (24) in a wall (23) of the heating device.

4. A heating device according to any preceding claim, in which the deflector member (10) has an air inlet projection (12) which defines an air inlet passage and which extends to or beyond a wall (23) of the fire box.

5. A heating device according to any preceding claim, in which the deflector member (10) is releasably mounted adjacent an external wall (23) of the device, the deflector member being provided with a first air inlet coupling (12), and the wall with a second, complementary, coupling (24), the first and second complementary couplings (12, 24) being releasably engaged so as to cooperate in providing an air inlet passageway from the outside of the device to the deflector member.

6. A heating device according to any preceding claim, in which the deflector member has an air outlet (13) that is non-round.

7. A heating device according to claim 6, in which the deflector member has an air outlet (13) that is generally elliptical.

8. A heating device according to any preceding claim, in which the deflector member has an air outlet that is of reduced cross-sectional area at a point nearer the fire than at a point further from the fire.

9. A heating device according to any preceding claim, in which the deflector member (10) has a generally downwardly facing surface, and in which that downwardly facing surface is provided with an air outlet (13).

10. A heating device according to claim 9, in which the downwardly facing surface is provided with a plurality of air outlets (13).

11. A heating device according to any preceding claim, in which the deflector member has a line of downwardly facing air outlets adjacent its front edge.

12. A heating device according to any preceding claim, in which the deflector member has a line of downwardly facing air outlets adjacent its rear edge.

13. A heating device according to any preceding claim, in which the deflector member has a line of downwardly facing air outlets adjacent one, or both, of its side peripheral edges.

14. A heating device according to any preceding claim, in which the deflector member (10) has at least one air outlet (13) at a generally central position, spaced from its peripheral edges.

15. A heating device according to any preceding claim, in which the deflector member (10) has a line of downwardly facing air outlets across its plan area and spaced from its peripheral edges.

16. A heating device according to any preceding claim, in which the deflector member has a first downwardly facing surface and a second downwardly facing surface inclined to the first surface.

17. A heating device according to claim 16, in which both surfaces have at least one air outlet.

18. A heating device according to claim 16 or 17, in which the two surfaces meet at an angle and at least one air inlet is provided at their junction.

19. A heating device according to claim 18, in which the two surfaces meet at a line and a row of air outlets is provided on the line.

20. A heating device according to any preceding claim which is provided with a flange (21) which in use abuts a wall (23) of the device, either directly or via a seal (26).

21. A heating device substantially as described herein with reference to Figures 2 to 7 of the accompanying drawings.

22. A deflector, or baffle, member (10) adapted to be introduced in use to a fire box of a heating appliance, and having air supply means (13) and being adapted to be replaced readily.

23. A deflector member according to claim 22, which is provided with a plurality of air outlets (13) adapted to supply air, in use, to a fire box (1).

24. A deflector member according to claim 22 or claim 23, which has a surface which in use is downwardly facing relative to the fire box, and which is provided with at least one air outlet.

25. A deflector member according to any preceding claim, in which the air supply means comprises a non-round air outlet (13).

26. A deflector member adapted to be installed at an upper region of a fire box, the deflector member having an air inlet, and an air outlet aperture, and a fold line about which it is folded, the air outlet aperture being near or on the fold line.

27. A deflector member according to any one of claims 22 to 26, which has a downwardly projecting lip (20) at its forward end.

28. A deflector member substantially as described herein with reference to Figures 2 to 7 of the accompanying drawings.

29. A method of reducing the maintenance costs of operating a heating appliance which is provided with a deflector member (10) which has an air supply (13), the method comprising making the deflector member easily removable.

30. A method of manufacturing an air supply component (10) for a heating appliance which has an air outlet (13), comprising providing a hole in the material of the component, the hole being a proto-air outlet port, and deforming, by for example bending or folding, the component so that the shape of the proto-air outlet is changed.

31. A method according to claim 30, in which the component is deformed at the region of the proto-air outlet.

32. A method according to claim 30 or claim 31, in which the proto-air outlet is round, the air outlet after deformation of the component being non-round.