Atmospheric gas burners are known that are made reciprocally coupling the head and the cup of the same burner so that to define both a mixing chamber for mixing primary air and gas, in order to obtain a fuel mixture, and a distribution chamber for supplying a circumferential flame spreader with said fuel mixture. In addition, it is known to obtain, using a substantially flat separating element disposed between the head and the cup of the burner, at least two overlapped ducts, one of them being intended for allowing the primary air inflow into the burner cup, and the other for allowing the air transferring from the mixing chamber to the distribution chamber of the burner. That causes the mould shape for realizing the head and cup of the burner to be extremely geometrically simple.
It has to be observed that, herein and after, with the term “duct” it has to be intended not only substantially cylindrical tubular ducts, opened at the two bases, but further any other channeling type, having any shape or any characteristic, being able to contain and allow the fluid or fluid mixture passing therethrough.
For example, the Patent Application EP-A-1297281 in the name of the Applicant, describes a gas burner of the type comprising a burner cup being able to accommodate an injector for the fuel gas, a burner head coupled to said cup and comprising a distribution chamber for a first circumferential flame spreader, and a mixing chamber for mixing primary air and fuel gas to set up a fuel mixture. In addition, said burner comprises a plurality of ducts for transferring the fuel mixture from said mixing chamber to said distribution chamber, an equal number of inflow ducts of the primary air from the outer environment into said burner cup, as well as a flat separating element, having a cross shape, disposed between the afore mentioned transferring and primary air inflow ducts. Such a separating element is blocked between the head and cup of the burner, once the head is rested and fixed on the cup, thereby allowing the functioning thereof for separating the burner inner space and as a result for obtaining one or more primary air inflow ducts and an equal number of reciprocally overlapped ducts for transferring the fuel mixture.
This solution, as afore mentioned, although allows to simplify the mould shapes for obtaining the head and cup of the burner, together with the fact also to ensure the realization of the separating element by simple shearing, it is not free of drawbacks.
As the Applicant has been able to verify, the efficiency of such a burner is somewhat reduced because of the turbulences that are created along the path followed by the fuel mixture inside the burner. This is also a consequence of the fact that the flows of air and fuel gas generated within the ducts for transferring the fuel mixture of the burner suffer from light leakages, which inevitably occur in burner itself.
Further, such leakages of fuel mixture, in the particular structure of the burner above described having the ducts for transferring the mixture overlapping the primary air flow ducts and kept apart from them by the afore said separating plane, involve as well the fact that the mixture eventually leaking from such transferring ducts is drawn, but only slightly, with the primary air towards the mixing chamber of the burner, where it results in an incomplete mixture of gas coming from the injector with the primary air, and then, again, in a reduced efficiency of the burner.
Object of the present invention is then to increase the afore described burner efficiency, thereby minimizing the turbulence of the fuel mixture and anyway maintaining unchanged the geometrical characteristics of the burner head and cup.
Further object of the present invention is also to obtain a burner being structurally simple and easy to assembly.