The subject matter of the present invention is a gas burner according to the preamble of the main claim. Such preamble can be read in DE9203212U1.

It is known that a usual plate gas burner comprises a plurality of plate-like elements arranged in parallel to each other and wherein a gas is injected by nozzles screwed into a manifold located at a first end of the burner. Such gas reaches, via the plates, another end of the burner where a diffuser is located and where such gas generates a flame being "ignited" by an ignition element (for instance a piezoelectric one) present in correspondence with such diffuser .

The plurality of plates is thus crossed by a fluid, typically water, duct, such duct being placed orthogonally to such plates. The latter are usually coupled with each other in a "packed" arrangement by means of one or several tie rods and by the above mentioned duct itself.

It is a known practice implementing the gas manifold by extrusion. Consequently, the manifold has a tubular shape, but generally its cross-section is polygonal, and it is fixed to the burner (or better, to its body defined by the plurality of coupled-together plates) by using specific square or L-shaped support elements which are secured to the sides of the burner body (by means of screws) at one hand, and to said extrusion (also by means of screws) at the other hand. The latter screws are provided in correspondence with and outside the sides of such body.

Such way of binding the gas manifold involves non- negligible costs bound to the use of the support elements and of their respective screws. In addition, obtaining a manifold by extrusion (which made necessary by the need for fitting it to the flat surfaces suitable for making it possible the use of screws for securing it to the support elements) also has a non-negligible cost.

A purpose of the present invention is mainly to offer a plate gas burner for boilers that can be obtained in a simpler way and at more reasonable costs.

These objects and others that will be apparent to those skilled in this art are achieved by a burner according to the attached claims.

For a better understanding of the present invention, the following drawings are attached for merely explanatory, not limitative, purposes, wherein:

figure 1 shows an exploded perspective view of a first embodiment of a burner according to the invention;

figure 2 shows a perspective view of the burner of figure 1 once assembled;

figure 3 shows a view similar to that of figure 1, but for a variant of the burner according to the invention;

figure 4 shows a perspective view of the burner of figure 3 once assembled;

figure 5 shows an exploded perspective view of a further variant of the burner according to the invention; and

figure 6 shows a perspective view of the burner of figure 5 once assembled.

In the figures, equal parts are identified by the same reference numerals.

With reference to figures 1 and 2, they show a burner 1 having a body 2 defined by assembling a plurality of platelike elements or simply plates 3 arranged in a longitudinal plane P (only two shown in figure 1) parallel to each other. Such a burner, known by itself in the state of the art, presents a first end 5 in correspondence with which there is placed a gas manifold 6 and a second end 7 where there is placed a flame diffuser 8.

Every plate comprises internal ducts 9 and 10 opening in correspondence with the ends 5 and 7 of the burner body 2. Specifically, in correspondence with the end 5, every duct 9 and 10 presents a widened opening 13 in correspondence with which there is located a respective gas nozzle 15 associated with the manifold 6. In this way, the gas carried by the manifold in correspondence with every plate 3 can reach, via the ducts 9 and 10, the diffuser 8 where a flame is created thanks to the operation of an ignition element (not shown) present on a side of the diffuser.

The gas manifold 6 is defined by one tubular duct with no closing plug (or simply tube) which is folded and shaped in such a way as to assume a substantially U-shape and consequently presents two parallel arms 17 and 18 carrying the gas nozzles 15 spaced away from each other so as to exactly mate the widened opening 13 of the plates 3. The latter preferably feature an outwardly countersunk shape to make it easier for the gas coming from its corresponding nozzle go in.

The arms 17 and 18 of the manifold 6 are connected to each other by a folded part 19, integral with such arms, whereas an end fitting 20 is present in correspondence with the free end of the arm 17; such fitting is suitable for being connected to a usual burner gas feeding.

Conversely, the free end of the other arm 18 is closed by way of a known mechanical processing which allows to melt and simultaneously deform the tube so as to obtain a closing bottom without using additional elements.

The manifold 6 is bound to the body 2 by elements 25 secured to opposed sides 26 and 27 of such body. Every element 25 is shaped in such a way as to shape-couple with the plates 3 defining such sides (or extremal side plates, identified by 3F in the figures) . However, in general it presents end fins 30 folded towards the inside of the burner body 2, projecting from a body or a central portion 31 which presents holes 32 suitable for receiving fixing members 33 (screws, rivets, or the like) which bind the element 25 to the body 2. From such central portion, in parallel to the first end 5 of the body 2, a number of tabs 34, folded towards the inside of the body 2, and perforated in 35, project, suitable for co-operating with the gas nozzles 15 which inject the gas into the side plates 3F. Specifically, inside the holes 35 of such tabs there is located and secured a pair of nozzles 15 which is formed, in a usual manner, of a faceted body 38 integral with the final section of the nozzle 39 itself (facing the opening 13) and screwed in a corresponding seat of the manifold 6, not shown. Every nozzle 15 suitable for co-operating with the plates 3F is screwed in the manifold 6 and inserted in the hole 35 of the tab 34 of the elements 25. Such elements 25 are secured to the body 2 and coupled with further comblike members or L-shaped brackets 40, with elongated notches 41 in a flat portion 45 thereof, which brackets are located in correspondence with the plates 3F in order to further provide a support for the manifold and its binding to the burner body 2. The brackets or comb-like members 40 are secured to the elements 25 by way of screws 47 and the notches contain the arms 17 and 18 of the manifold 6.

Finally, a further folded tube 43 crosses the body 2 in a position close to its second end 7: water flows through such tube and, the burner being in operation (flame present on the diffuser 8), is heated. The tube 43 is through- inserted into the holes 44 of every plate 3.

Thanks to the invention a burner is obtained wherein the gas manifold is easily associated with the burner body 2, whilst having a tubular shape that is simpler and less expensive to obtain as compared with the extrusion defining the known manifolds. Furthermore, thanks to the invention an optimum centering of the nozzles 15 is achieved in correspondence with the openings 13 of the plates 3 (or 3F) as well as an optimum spacing between the nozzles 15 and said openings 13, thus guaranteeing an optimum combustion and consequently reduced emissions.

In the solution of figures 1 and 2, the plurality of plates 3 is held assembled by the tube 43 properly associated therewith. Conversely, in the solution of figures 3 and 4 the plates 3 are bound to each other by means of tie rods 50 introduced into coaxial holes 51 of said plates and secured to the end elements 25 by means of nails or the like 53. In this variant, these elements do not shape-couple with the side plates 3F, but rather their central portion 31 is completely flat.

In this solution too, the manifold 6 is a folded tube and is supported by the elements 25.

In the solutions of figures 1, 2, 3, 4 the elements 25 that support and bind the manifold 6 to the body 2 of the burner 1 cover the sides 26 and 27 of such body only partially. Conversely, the variant of figures 5 and 6 shows a case wherein such elements fully cover such sides and the comb-like members or bracket 40 are not L-shaped, but present a flat portion 45 only (along with the notches 41) secured to their corresponding elements.

In the embodiment here examined the plurality or pack of plates 6 and the elements 25 are mechanically bound to each other thanks to the arrangement of the tube 43 therein. For this purpose, the elements 25 too are provided with through holes 66 for making said tube pass through. By way of mechanical processings, the duct is thus deformed to make it possible a force coupling with every plate, thus locking the pack of plates 3.

Thanks to the invention a compact, easy to implement gas burner is obtained, an optimum centering of the gas nozzles with the ducts of the plates and an optimum combustion being obtained.

In all above-described cases the elements 25, besides providing the centering of the nozzles with respect to the openings 13 of the ducts 9, hold a correct distance of the nozzles themselves from the openings of the ducts, thereby assuring an optimum draught and above all an optimum NOx emission level under any operating conditions.

Various embodiments of the invention have been described. However, others are also possible in the light of the previous description, for instance, every nozzle 15 might be one-piece with the gas manifold 6 or be directly obtained therefrom by way of an appropriate drilling and a subsequent processing of the manifold itself, if any, which leads to the creation of projecting "stern sheets" on the manifold, each defining a nozzle. Therefore, also this variant and others are to be considered to fall in the scope of the following claims.