WO2010109077A1

WO2010109077A1 - Grate construction

Info

Publication number: WO2010109077A1
Application number: PCT/FI2010/050235
Authority: WO
Inventors: Hannu Laajala
Original assignee: Hannu Laajala
Priority date: 2009-03-26
Filing date: 2010-03-25
Publication date: 2010-09-30
Also published as: FI8390U1; FIU20090112U0

Abstract

The invention relates to a grate construction (1), which consists essentially of plate metal, in which case the construction is essentially corrugated in cross- section, the corrugated angle being in the order of about 70 - 110 degrees, and in the grate there are holes/openings (4, 5) on both bottom (3) of the corrugation and in the area of the ridge (2). Particularly the holes/openings (4) in the area of the bottom (3) are substantially larger than the holes/openings (5) in the area of the ridge (2).

Description

Grate construction

The present invention relates to a grate construction, and more specifically a grate construction, which is used in a firebox using wood or a similar fuel.

Traditionally, a grate is formed of either an essentially planar bottom to the firebox, or a separate, essentially planar piece, but including holes or gaps, which is often made of cast iron, under which is usually, for example in sauna stoves and similar, an ash box, into which the combustion residues drop, and which can be emptied from time to time.

It is obvious that if the grate is simple a solid masonry surface, the effect of the grate on the combustion event will be quite small, and can in fact even be negative, because air promoting combustion cannot be led through a solid structure, without separate pipe or other structures.

A separate cast-iron or similar grate construction is better than the aforementioned construction, in that combustion air can easily come through the grate. The amount of combustion air can often be influenced by opening and closing the ash-box door.

Grates that are shaped in a specific manner are also known, one example of which is the grate construction with low corrugations, disclosed in British patent 25426 from 1896.

The present invention is intended to create a grate construction, with the aid of which the combustion event can be further improved and will also bring advantages to the ash formation from wood and the behaviour of the ash created.

The grate construction according to the invention solves many problems, which are described in the events depicted above. Combustion air is directed to where it is needed. During the combustion event, compaction, which interferes with combustion, does not occur. The grate construction according to the invention can also be made using conventional engineering-shop tools and is extremely strong.

The aforementioned and other benefits and advantages of the present invention are achieved in the manner described as characteristic in the accompanying Claims.

In the following, the invention is described in greater detail with reference to the accompanying drawings, in which

Figure 1 shows an axonometric view of one embodiment of the grate according to the invention;

Figure 2 shows a side view of the grate construction according to figure 1 ; and

Figure 3 shows an end view of the grate construction.

All three figures can be examined simultaneously. Thus, the grate 1 is formed of a metal plate 2 bent into a corrugated form. This shape is shown clearly in Figure 3. The folds of the corrugations are relatively steep, which differs significantly from known planar or gently corrugated solutions. However, it is obvious without being stated, that the shape of the corrugation can be altered as required. For example, if a basic plate is used, from which it is intended to make grates of differing widths, a lowering of the corrugation shape will mean an increase in the overall width of the grate. A change in the shape of the corrugation, as long as it remains within specific criteria, is not a critical property in terms of the invention.

The corrugated or folded shape is formed in the conventional manner of the ridge 2 of the corrugated and the bottom 3 of the corrugation. Depending on the fireplace, one or more grate components with a corrugated shape can be used for each fireplace. It can be seen clearly from the figures, that form the ridge 2 and bottom 3 of the corrugation are perforated. In this particular embodiment, the bottom of the corrugation is perforated with relatively large openings 4. Because ash and clinker tends to drop downwards and thus towards the bottom of the corrugation, a bottom with large holes will permit this to drop freely into the ash box or similar. The corrugation ridge too is equipped with holes 5, which are clearly smaller than the holes 4 on the bottom. A third type of hole 6 is in the side of the corrugation. This is because it is wished to avoid larger solid surfaces.

When pieces of wood are placed on top of the grate, their contact surface with the grate 1 remains quite small. Thus, there is a large ignition surface and few surfaces tightly against the wood that are impenetrable by air. Both at the moment of ignition and also during the combustion event, the supply of air is unobstructed, which means that the pieces of wood ignite well over a large area and also burn well and efficiently.

An efficient combustion event also means clean combustion. Ash too is formed evenly and exits effectively dur to the grate according to the invention. Due to the small contact surface, areas of poor combustion do not remain between the wood and the grate. In addition, wood burned on a grate according to the invention has the property of moving as combustion proceeds, because a certain kind of movement occurs in the combustion chamber due to the corrugated nature of the grate.

As stated, it is easy to make grates of different widths form the same initial piece, by altering the angles and side lengths of the corrugation.

If desired, the perforations can be round or oval or of any shape whatever. They can be transverse, longitudinal, or set at an angle to the said directions.

As clearly stated above, the corrugations of the grate according to the invention are relatively sharp edged. In fact, it would be clearly more correct to refer to folds than corrugations. A quite large part of the advantages of the invention are based on the sharply folded shapes. Thus, the advantages brought by a construction according to this grate cannot be achieved using a gently corrugated grate according to the prior art.

In practical tests, it has been shown that the angle of the corrugation of the grate is approximately in the range 70 - 110 degrees. Even this setting can be narrowed to 80 - 100 degrees, with which the very based efficiency will be achieved.

In practical tests, clear improvement in efficiency over conventional grates have been achieved, it being possible to speak of an improvement of 20 - 25 %, which is of great importance in terms of fuel costs. In addition to the actual raw- material costs, a more complete combustion event is achieved, which leads to cleaner combustion gases and a cleaner burner interior, as well as to a reduction in the amount of combustion products.

Many variations of the basic concept are possible. The manufacturing material is mainly steel plate.

Claims

1. Grate construction (1), which consists essentially of plate metal, in which there are holes for combustion air and the removal of ash, characterized in that the construction is essentially corrugated in cross-section, in such a way that the corrugated angle is in the order of about 70 - 110 degrees, and there are in it holes/openings (4, 5) on both bottom (3) of the corrugation and in the area of the ridge (2).

2. Grate construction according to Claim 1, characterized in that the holes/openings (4) in the area of the bottom of the corrugation are substantially large than the holes/openings (5) in the area of the ridge (2).

3. Grate construction according to Claim 1 , characterized in that there are holes/openings (6) also in the area of the sides of the corrugation.

4. Grate construction according to Claim 1 , characterized in that the shape of the corrugation (2, 3) of the construction and/or the length of its sides can be altered in order to change the width of the construction.

5. Grate construction according to Claim 1 , characterized in that the angle of the corrugation of the grate is in the order of 80 - 100 degrees.