WO2003042598A1

WO2003042598A1 - A mobile hearth for containing a fire

Info

Publication number: WO2003042598A1
Application number: PCT/DK2002/000768
Authority: WO
Inventors: Jørn G. JENSEN
Original assignee: Jensen Joern G
Priority date: 2001-11-16
Filing date: 2002-11-15
Publication date: 2003-05-22
Also published as: DK200100312U3

Abstract

Hearth for containing a fire comprising a firing cylinder having a first and a second end, a supporting burning plate for supporting said first end, a number of legs supporting said burning plate and a grid placed in the firing cylinder. This hearth is advantageous, in that it is mobile and allows relatively long pieces of wood to be burnt within the firing cylinder supported by the grid.

Description

A Mobile Hearth for Containing a Fire.

The present invention relates to a mobile hearth for containing a fire. Fireplaces today are considered generally to provide an aesthetic pleasure as opposite to the utilitarian purposes of a furnace or stove. Outdoor fireplaces are additionally to the aesthetic pleasure used for cooking.

Outdoor fireplaces are mainly established when and where desired with use of regularly available materials such as rocks, but what may considered an outdoor fireplace is also well-known in a form typically intended for use as barbecue grills and have concrete block constructions. Many types of barbecue type grills are also known, but none of these are intended for the burning of wood, and hence does not provide the aesthetic qualities discussed above with regard to a wood-burning fireplace. Wood fires outside are also valued for the warmth obtainable therefrom and for enabling the cooking of food. However, there are a few draw backs associated with the use of the wood fire built outside upon the ground.

In particular it is considered that many people will like to enjoy a wood burning fire upon a deck of a house, but a deck typically made of wood can burn quite readily. Construction of a fireplace in concrete or stone is simply not feasible upon a deck, and while the use of barbecue grills of various sort used upon a wood deck is considered to be widely practiced is a grill for cooking using charcoals and is not intended to bum wood nor permit viewing of a fire therein. Open wood fires built upon the ground had an unpleasant tendency to spread and are generally dangerous, if not illegal if built in places other than those specifically designated for camp fire.

It is the object of the invention to provide a fireplace which solves at least some of the above-mentioned problems. The object is achieved by providing a hearth for containing a fire comprising a firing cylinder having a first and a second end, a supporting burning plate attached to said first end and a number of legs supporting said burning plate, and a grid placed inside the firing cylinder. This hearth is advantageous, in that it allows pieces of wood to be burnt within the firing cylinder supported by the grid. In the firing cylinder, relatively long pieces of wood can burn. Due to an upright possision of the pieces of burning wood in the firing cylinder, the heat from fire in the lower end of the firing cylinder will be transferred along the sides of the pieces of wood. The result is, that the wood is preheated, and it will burn more easily. The sup- porting burning plate prevents ash and glowes from dropping down on the ground as well as reflecting the heat in an outward direction. The hearth is held a distance from the supporting surface for example a wood deck, terrace, lawn or the like by the legs, so the hearth can also be placed on materials such as wood. Furthermore, the present hearth is mobile, and can be moved to the place, where a fireplace is needed. It is even possible to move the hearth when the fire is burning.

In another embodiment of the invention the second end of the firing cylinder is having a conical bent out portion to avoid friction between firewood in the firing cylinder and the second end of the firing cylinder. The bent of the second end of the firing cylinder is advantageous, because it allows the fire wood to drop down in the firing cylinder as the wood is partly burnt instead of being held back by a sharp edge of the cylinder.

In another embodiment of the invention the firing cylinder further comprises ventilation apertures at least some of the apertures being proximate to said first end. Nentila- tion apertures allows fresh air to be let into the firing cylinder for fueling the fire. This will make the fire burn more easily.

In a further advantageous embodiment of the invention the hearth additionally comprises a securing member having a cross section area which is of the same geometrical shape of the cross section area of the firing cylinder, but slightly larger, which allows the securing member to cover at least some ventilation apertures at least partly when placed around the firing cylinder. In the end of the firing/burning process it is advantageous to have the opportunity to prevent ash and glows from the firing process to spread through the ventilation holes and to reduce the air into the hearth to stop the firing process. The provided securing member can at least partly cover the ventilation apertures, and consequently prevent ash from spreading as well as prevent fresh air from flowing into the hearth. In another further advantageous embodiment of the invention the burning plate is having a sunk face in the inside of which the first end of the firing cylinder is accomo- dated. The sunk face inside the burning plate provides a more stable base for the firing cylinder and reduces the risk of tilting the firing cylinder.

In another embodiment of the invention the hearth further comprises an insulating plate arranged at a distance below said burning plate. The isolating plate provides an additionally isolating of the heat from the hearth as well as the opportunity to warm up food such as bread on the insulating plate.

In an additional embodiment of the invention the insulating plate is having an area at least as big as the area of the burning plate. A bigger isolating plate is advantageous, as it reflects a greater part of the heat radiation from the hearth.

In another embodiment of the invention the insulating plate further comprises a number of spacers keeping the distance between the insulating plate and the burning plate.

In another embodiment of the invention the hearth further comprises an insulating member which has a cross section area which is of the same geometrical shape as the burning plate, but slightly larger, and a height substantially equal to the length of the spaces. The use of the isolating member will close in the volume between the insulating plate and the burning plate, consequently making it possible to use that volume as an oven. ^•

In another embodiment of the invention the grid is having a pyramidal shape A pyramidal form of the grid is found to provide a very good support of the burning wood. When the grid is hot, it is easily bent. By providing a pyramidal shape, the forces from the pressure of the burning wood is directed along the sides of the pyramide to the firing cylinder. The result is, that the grid is not deformed, and therefore it is able to maintain a good support of the burning wood. The invention will be explained in more details with reference to the accompanying drawings, in which

Fig. 1 shows an embodiment of the invention in a perspective view, Fig. 2 shows an embodiment of the invention in an exploded view, and

Fig. 3 shows a detail of an embodiment of the invention, where a grid is visible, and

Fig. 4 shows a cross section view of an embodiment of the invention.

Fig. 1 shows a hearth comprising a firing cylinder 1 having a first 2 and a second 3 end. The firing cylinder 1 can be made from sheet metal, which is folded. The firing cylinder acts as a chimney as well as a hearth. Inside the firing cylinder a grid 6 is attached. The corners of the grid 6 are protruding through apertures in the firing cylinder 1. The firing cylinder 1 is supported by a burning plate 4. A number of legs 5 are supporting the burning plate 4. Inside the burning plate 4 a sunk face 10 is provided. The purpose of the sunk face 10 is to provide an accommodation of the firing clinder 1.

The sunk face 10 prevents tilting of the firing cylinder 1 and prevents ash and glows from escaping between the firing cylinder 1 and the burning plate 4. When wood is burning in the firing cylinder 1 the fire will not spread outside the firing cylinder 1, and ash will accumulate on the burning plate 4 inside the firing cylinder 1. Since the burning plate 4 is held in a distance from the supporting surface by the legs 5 the heat transferred from the fire to the ground can be reduced. It is therefore possible to use the hearth according to the invention in places where it is normally not wise to have a fire. It is also possible to use the burning plate 4 for cooking while flames are burning inside the firing cylinder 1. This is advantageous over commonly used barbecue grills, as it is not possible to use a barbecue grill for cooking while flames are still burning.

It has been found that ventilation apertures 7 provided proximate the first end of the firing cylinder makes the fire in the firing cylinder 1 burn more easily and cleanly. It has also been found that additional ventilation apertures 8 at different distances from the first end 2 of the firing cylinder 1 can act both as cooling for the firing cylinder 1 itself as well as supplying extra air to the fire. The figure also shows an insulating plate 11 held at a fixed distance below the burning plate 4 by a number of spaces 12. The insulating plate 11 fiirther reduces the heat transfer from the hearth to the supporting ground. It is also possible to use the volume between the insulating plate 11 and the burning plate 4 for cooking.

Fig. 2 shows an embodiment of the invention in an exploded view. The firing cylinder 1 is round in this example, but can have other shapes, for example triangular of rectangular. The securing member 9 has the same geometric shape as the firing cylinder 1, in this example shown as round, but has slightly larger diameter. It is therefore pos- sible to slide the securing member 9 down along the firing cylinder 1 until the securing member 9 reaches the burning plate 4. When the securing member 9 reaches the burning plate 4 the securing member 9 will cover at least some ventilation apertures 7, at least partly. If the fit between the firing cylinder 1 and the securing member 9 is tight enough, the air flow through the ventilation apertures 7 will stop, and the fire will quickly die. The use of the securing member 9 also has the advantage that ash and glows cannot spread through the ventilation apertures 7. After the fire has stopped burning, there can be glows for several hours. The securing member 9 gives the possibility to leave the hearth before the glows have died. Furthermore, an insulating member 13 is provided. It has the same geometric shape as the firing cylinder 1, but has a slightly larger diameter. It is therefore possible to slide the insulating member 13 down along the firing cylinder 1 until the insulating member 13 reaches the insulating plate 11. When the insulating member 13 reaches the insulating plate 11 the insulating member 13 is supported by the insulating plate 11 and encloses the volume between the burning plate 4 and the insulating plate 13. This will cause the temperature to in- crease in the volume, and the volume can be used as an oven.

In another embodiment of the securing member 9, it is provided with a number of ventilation apertures similar to the ventilation apertures 7 of the firing cylinder 7. By rotating this securing member around the firing cylinder 1 while it is in its position on the burning plate 4 it is possible to control the amount of air flow into the firing cylinder. When the fire is dying out, this securing member can be rotated until ventilation apertures 7 of the firing cylinder 1 is closed. In fig. 3 an embodiment of the grid 6 is shown inside the firing cylinder 1. The grid 6 is here formed by a sheet of metal with a number of apertures of different sizes and shapes.

In fig. 4 the conical bent out portion 14 of the second end 3 of the firing cylinder 1 is shown. The purpose of the bent out portion 14 is to prevent the edge of the second end 3 of the firing cylinder 1 to capture the wood. It is important to avoid capturing of the wood by the edge of the second end 3 of the firing cylinder 1, since captured wood can rotate in the captured point when the wood is burned to ash inside the firing cylinder 1 and burning wood can drop outside the firing cylinder 1.

Claims

1. Hearth for containing a fire comprising a firing cylinder (1) having a first (2) and a second end (3), a supporting burning plate (4) for supporting said first end (2), a num- ber of legs (5) supporting said burning plate (4) and a grid (6) placed in the firing cylinder (1).

2. Hearth according to claim 1 where said second (3) end of the firing cylinder (1) has a conical bent (14) to avoid friction between firewood in the firing cylinder (1) and the second end (3) of the firing cylinder (1).

3. Hearth according to any of the claims 1 to 2 where said firing cylinder (1) further comprises ventilation apertures (7,8), at least some of the apertures (7) being proximate to said first end (2).

4. Hearth according to claim 3 where said heart further comprises a securing member (9), said securing member (9) having a cross-section area which is of the same geometric shape as the cross section area of the firing cylinder (1), but slightly larger, which allows the securing member (9) to cover at least some ventilation apertures (7), at least partly when placed around the firing cylinder (1).

5. Hearth according to any of the claims 1 - 4 where said burning plate (4) has a sunk face (10) in the inside of which the first end (2) of the firing cylinder (1) is accommodated.

6. Hearth according to any of the claims 1 - 5 where said hearth further comprises an insulating plate (11) arranged at a distance below said burning plate (4)

7. Hearth according to claim 6, where said insulating plate (11) has an area at least as big as the area of the burning plate (4).

8. Hearth according to any of the claims 6 to 7 where said insulating plate (11) further comprises a number of spacers (12) keeping the distance between the insulating plate (11) and the burning plate (4).

9. Hearth according to claim 8 where said hearth further comprises an insulating member (13), said insulating member (13) having a cross sectional area which is of the same geometric shape as the burning plate (4), but slightly larger, and a height substantially equal to the length of the spacers (12).

10. Hearth according to any of the claims 1 to 9 where said grid (6) has a pyramidal shape.