GB2177192A - Cooking stove - Google Patents

Abstract

A cooking stove comprises a double-wall enclosure (1) filled with sand, a hearth member (25) acting as a support for a cylindrical cooking container (35), a damper with draught holes and a discharge chimney (23). The combustion gases (38) leave the hearth via an aperture in the front of the member (25), flow around the container (35) through an annular space (37) closed at the top before reaching the discharge chimney (23). Cheap to manufacture and easy to assemble, made from components which are easily replaceable after they have worn out, this stove provides a high calorific efficiency to counteract rapid deforestation of developing countries. <IMAGE>

Description

SPECIFICATION Stove This invention relates to a multi-fuel stove comprising a hearth, a cooking container and a generally cylindrical enclosure the front of which is provided with a damper for fuel charging comprising apertures for the air for combustion and, at the rear, an opening for the discharge of the combustion gases.

In various parts of the world, and particularly in developing countries, food is cooked on open fires using a very considerable quantity of wood, a factor which largely contributes to deforestation of these areas with resultant famine.

The object of this invention is to provide a stove enabling food to be cooked for communities, the stove having a high calorific efficiency, being easy to assemble at the place of use, and of the lowest possible cost price. To this end, the stove is characterised in that the hearth is formed by a member engaging in the enclosure and having a top part on which the base of the container rests, the container having substantially cylindrical walls co-operating with the inner wall of the enclosure to define a cylindrical annular space, the container and enclosure being so shaped as to close the top part of the annular space, the front part of said member facing the damper having an aperture through which the hearth communicates with said annular space so as to form a combustion gas path following the periphery of the container in order to reach the discharge aperture.

With this arrangement the stove efficiency is very high, at least 80% of the heat produced by combustion being used directly for cooking. The stove also requires only a few components which make it cheap to manufacture and easy to assemble and use.

A preferred embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which Fig. 1 is a front view of the stove.

Fig. 2 is a vertical section through the stove.

Fig. 3 is a plan view of the stove, the cooking container having been removed.

Fig. 4 is a side view of the stove damper.

The stove illustrated in Figs. 1 to 3 comprises a generally cylindrical enclosure 1 formed by a double wall made from an inner metal sheet 2 and an outer metal sheet 3, a base 4 and a top annular closure 5. Bent flat metal sections 6 and spacers 7 make the enclosure mechanically stable. The various parts of this enclosure are assembled at the place of use of the stove either by means of bolts or rivets 8. The cylindrical space between the metal sheets 2 and 3 is filled with sand 9 or some other material which is a poor conductor of heat available locally, such as clay or fine pieces of laterite.

An aperture 10 for charging solid fuel, particularly wood, is formed in the bottom front part of the enclosure 1. This aperture is provided with a damper 11 comprising two slides 12, 13, one 12 adapted to regulate the opening of the draught holes 14 for primary air and the other 13 for regulating the opening of the draught holes 15 for the preheated secondary air. The draught holes 14 are disposed in the bottom of the damper 11 and supply air beneath the combustion hearth, while the draught holes 15 lead into an air preheating chamber 16 fixed on the inner wall of the damper 11 (Fig. 4). The air leaves this chamber via an opening 17 formed in the top to reach the hearth in the form of preheated secondary air. The top of the rear part of the stove has an opening 24 communicating with the chimney 23 which can be provided with a damper (not shown).

The hearth is formed by a sheet steel or cast iron member 25 fitting into the enclosure 1 and comprising a cylindrical base 26, a conical part 27, and terminates at the top in a horizontal ring 28 whose outer contour corresponds substantially to the inner wall of the enclosure 1. Parts 26 to 28 of member 25 have a sector-shaped aperture 29 (Fig. 3) facing the damper 11 and bounded on both sides by vertical walls 32, 33 connected to the member 25. This aperture 29 together with its two walls 32, 33 thus forms a passage to allow charging of the wood, removal of ash and, as will be apparent hereinafter, the upward discharge of the combustion gases. A preferably cast iron grating 30 is supported by the central part of the member 25 and acts as the actual combustion support.

The periphery of the conical part 27 has two conduits in the form of metal pipes 20, 21 adapted to supply the preheated secondary air from the preheating chamber 16 to the rear of the stove in order to introduce it via apertures 31 to the interior of the hearth.

The detachable cooking container 35 is in the form of a cylindrical-wall flat-bottomed pot with handles 36. It is supported by the horizontal ring 28 of the member 25. The outer surface of the cylindrical walls co-operates with the inner wall 2 of the enclosure 1 to define a cylindrical space 37 for the combustion gases. The top annular closure 5 of the enclosure 1 is in contact with the walls of the container over its entire periphery so as to close the cylindrical space 37 at the top. This space is partially closed at the bottom by the horizontal ring 28 in contact with the base of the container 35. The hearth communicates with this annular space 37 in the front of the stove remote from the aperture 22 at the level of the sector-shaped opening 29 of the member 25.The high-temperature gases leave the hearth via this open sector 29, rise in the front part of the stove towards the annular space 37, flow around the container 35 therein over its entire circumference, as shown by arrows 38, then leaving the stove via the chimney 23 at the rear thereof.

The heat thus flows over the entire periphery of the container which is surrounded by enclosure 1 over at least 90% of its cylindrical surface. Thus an optimum calorific efficiency can be obtained.

Parts 2 to 8 of the enclosure 1, the container 35, the damper 11 and the parts 25 and 30 of the hearth are prefabricated and taken to the place of use where the stove can be quickly assembled. The outer diameter of the stove in the variant embodiment described is 102 cm and that of the cooking pot 78 cm, the annular space 37 between the enclosure 1 and the continer 35 is 3 cm.

Of course the embodiment described may be modified as required. More particularly, the outlet aperture 22 could be provided with a baffle in the form of a substantially spherical metal sheet secured to the bottom part thereof. Also, the enclosure can be allowed to rest directly on the ground without a base 4.

The stove can also be heated by gas or paraffin burners introduced into the hearth member 25.

All the parts of the stove are replaceable after wearing out.

Claims (9)

1. A multi-fuel stove comprising a hearth a cooking container and a generally cylindrical enclosure the front of which is provided with a damper for fuel charging comprising apertures for the air for combustion and, at the rear, an opening for the discharge of the combustion gases, wherein the hearth is formed by a member engaging in the enclosure and having an upper part on which the base of the container rests, the container having substantially cylindrical walls co-operating with the inner wall of the enclosure to define a cylindrical annular space, the container and enclosure being so shaped as to close the top part of the annular space the front part of said member facing the damper having an aperture through which the hearth communicates with said annular space so as to form a combustion gas path following the periphery of the container in order to reach the discharge aperture.

2. A stove according to claim 1, wherein said member has a cylindrical base, an upwardly flaring conical part and terminates at the top in a horizontal ring whose outer contour corresponds substantially to the inner wall of the enclosure said member having a sector-shaped said aperture situated facing the damper.

3. A stove according to claim 2, wherein the central part of said member supports a grate which acts as a combustion support.

4. A stove according to claim 2 or claim 3 wherein the horizontal ring constitutes said upper part on which the base of the container rests.

5. A stove according to any preceding claim, wherein the damper has two air inlets, one of which is disposed in the bottom part of the damper and is adapted to supply air below the hearth, the other being disposed in the top of the damper and having, on the inner surface of the damper, a pre-heating chamber adapted to provide secondary preheated air to the top part of the hearth.

6. A stove according to claim 5, wherein said member has conduits adapted to supply preheated air from the preheating chamber to the rear part of the stove and introduce it via apertures.

7. A stove according to any preceding claim wherein the container has a height such that it is surrounded by the enclosure over at least 90% of its cylindrical surface.

8. A stove according to any preceding claim wherein the enclosure is formed by two concentric cylindrical metal sheets, the space between the two sheets being filled by a material which is a poor thermal conductor and which is available at the place of use of the stove.

9. A stove substantially as hereinbefore described with reference to the accompanying drawings.