US20170268788A1

US20170268788A1 - Burner and cooking apparatus therewith

Info

Publication number: US20170268788A1
Application number: US15/456,554
Authority: US
Inventors: Augusto Marco Culatti; Marcello Toscani; Valter Secomandi
Original assignee: Castfutura SpA
Current assignee: Castfutura SpA
Priority date: 2016-03-15
Filing date: 2017-03-12
Publication date: 2017-09-21
Also published as: ITUA20161671A1; MX2017003383A

Abstract

An over or grill burner includes a hollow body with a supplying port receiving a gaseous fuel mixture and outlet holes emitting the gaseous fuel mixture, and a conveying duct conveying the gaseous fuel mixture toward the hollow body, which has a delivering port and a supplying/mixing port with a first aperture for a fuel gas and a second aperture for a gaseous combusting product, and a reflector conveying a flame produced by combustion of the fuel mixture from the outlet holes. The supplying port of the hollow body and the delivering port of the conveying duct have a substantially circular cross-section and are connected to each other in a freely rotatable manner.

Description

FIELD OF THE INVENTION

The present invention relates to an oven or grill burner.

BACKGROUND OF THE INVENTION

Oven or grill burners typically comprise a hollow box body provided with a supplying port, which, in use, is supplied with a gaseous fuel mixture.
Such mixture is discharged from a plurality of outlet holes and it is ignited by a suitable igniter.
The flame generated in this manner therefore is conveyed by a reflector coupled to the burner.
The box body is coupled to a duct conveying the gaseous fuel mixture.
Such fuel mixture comprises a fuel gas (for example methane, town gas, propane or mixtures of different gases) and a comburent, usually air.
The mixing percentage between fuel and comburent (oxygen of air) is such to allow combustion to take place only downstream the supply of the fuel mixture from the holes of the box body, according to known techniques and therein no further reference is made thereto.
Examples of known burners are described in English patent GB1444333 and in U.S. Pat. No. 5,249,958 and U.S. Pat. No. 5,992,770.
This type of burners usually is installed in ovens or grills of household appliances.
Although being perfectly functional, however such burners have some drawbacks.
Firstly it has to be noted that the size and positioning of burners in ovens are subjected to differences from one to another oven model. Such differences are due to conventional construction configurations of ovens and also to security regulations. For example the nozzle injecting the gas in the mixer with combustion air can be arranged at any walls of the oven, except for the door and in any point of the corresponding wall and moreover it can also be provided outside the oven chamber or inside it.
As it will be disclosed below, the internal or external positioning of the gas injecting nozzle leads to completely different operating conditions and it also constraints the position of the nozzle at the wall. When the gas injecting nozzle is inside the oven chamber, the mixer has to necessarily take the combustion air inside the oven compartment and therefore in order to avoid low oxygen contents due to pollution by combustion gases going up towards the discharge flue, generally said nozzle and then the associated mixer have to be provided in positions remote from the burner and from the discharge flue and also preferably in the lowest area of the oven chamber where hot combustion gases do not diffuse due to the natural convection principle and also due to the flue effect.
A further adverse effect that can result in positioning the fuel gas injecting nozzle in the bottom area of the oven is the fact that combustion air in the upper area of the oven, that is at the top, is at a temperature higher than the air that—in the oven—is at the bottom. Since air density is in inverse proportion to the temperature, it results that, other factors being equal, the total amount of oxygen decreases as the temperature increases and therefore it is at a higher value in the lower part of the oven compartment.
On the contrary in other cases when the nozzle is placed outside it is possible for the wall through which it can be accessed to be a side wall and not the bottom wall, that is the wall opposite to the door, and in this case also the orientation of the burner relative to the oven chamber has an important role.
Such orientation is not only due to the several conventional sizes of the oven chambers, but also to the fact of positioning the burner with the best orientation and position to obtain a substantially even heating action in the oven compartment.
Other functional effects of the burner are described in more details below.
The several variants for positioning the gas injecting nozzles relative to the oven compartment and the several dimensions of the oven compartment, currently result in providing the burners with a plurality of shapes and sizes, with waste of money for keeping them in stock and for the manufacturing process which reduce the margins of burner manufacturers and of oven or kitchen manufacturers since they are obliged to produce burners dedicated to different oven models.
Moreover in conventional burners, the mixing between fuel gas and combustion air is usually performed very close to the box body by a venturi tube mixer by means of which an increase in the speed of the injected gas in a narrowing generates an action sucking combustion air through a window of the venturi tube which is progressively adjustable in size.
Since the mixing portion is short with respect to the first outlet holes of the burner (venturi portion) due to dimension reasons between the first holes of the burner the mixture is turbulent and the flame is not stable. By providing a feeding portion, as the elbow tube provided in the described embodiments, the long portion between venturi and the inlet in the burner allows the turbulence to be decreased. Moreover the two recesses between the central area of the burner and the gas outlet delivering holes exert a similar function of decreasing the turbulences particularly when the supplying tube is straight or the venturi tube is close to the burner inlet.
A certain unevenness of the mixture is also detected which contributes in further worsening the flame in the area of the first outlet holes, that is the holes close to the venturi tube and more precisely to the outlet thereof in the burner chamber.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome prior art drawbacks.
More particularly, it is an object of the present invention to provide a burner able to be easily installed in different types of ovens, reducing the need of providing burners of different configurations specially made for the several variants of installation.
Another object of the present invention is to provide a burner and an oven provided with such burner obtaining an improved combustion.
Another object of the present invention is to provide a burner and an oven provided with such burner wherein the combustion air has better characteristics for the combustion.
Another object of the present invention is to provide a burner and an oven provided with such burner having reduced dimensions as a whole, without worsening the combustion, while allowing a saving in overall dimensions of the burner parts in the oven.
It is also an object of the present invention to provide a burner and an oven provided with such burner that are quite cheap and strong.
These and further objects of the present invention are achieved by a burner and an oven provided with such burner embodying the characteristics of the annexed claims, which are an integral part of the present description.
The general idea at the base of the present invention provides to make a burner, in which the supplying port of the box body and the delivering port of the duct conveying the fuel gas mixture have a substantially circular cross-section and are fitted with each other in a freely rotatable manner.
Thus it is possible to rotate the duct conveying the gaseous fuel mixture such to orient the intake point according to any angle with respect to the supplying port of the box body.
This allows fuel gas delivering points placed in different areas of the oven to be reached and therefore this allows the burner of the invention to be arranged such to be adapted to ovens of different types, therefore making the burner more versatile than burners known in prior art and accomplishing at least a part of the objects listed above.
Moreover according to a further advantageous characteristic the fitting between the supplying port of the box body and the delivering port of the conveying duct can be sealed, a sealing element being preferably provided, preferably interposed therebetween.
Such sealing element is not generally necessary, but it can be provided in particular cases, since, in the area where the mixture enters the burner, the pressure of said mixture is generally lower than in other areas of the burner. Therefore in order also to promote a more efficient possibility in rotating and therefore orienting the tube feeding the mixture to the burner, the form where the sealing element is not present is preferred.
According still to another advantageous characteristic, the supplying/mixing port of the duct, where the fuel gas is injected through a nozzle and combustion air is sucked and mixed with said gas according to a predetermined stoichiometric ratio, is free to move along a circumference having as the center the one of the supplying port; this leads to an optimal versatility during the installation.
Another characteristic is the fact that there are provided devices for fastening the coupling between duct and body, intended to lock them together once the duct is arranged along a preferred direction; this allows the desired position to be locked in a simple manner on the whole.
Moreover in a further embodiment the conveying duct comprises an elbow placed between the delivering port and the supplying/mixing port, such elbow having preferably an angle of 90° thus to allow a particularly versatile installation.
Still according to an advantageous characteristic, the conveying duct comprises a converging/diverging portion downstream the supplying/mixing port, with reference to a direction supplying the gaseous fuel mixture towards said box body, to help gas and air to be pre-mixed.
Still according to an advantageous characteristic, the converging/diverging portion is placed downstream the supplying/mixing port and before said elbow with reference to a direction supplying the gaseous fuel mixture towards said box body of the burner.
Moreover according to an advantageous characteristic, the box body of the burner comprises a central portion in line with said supplying port from which two box wings radially extend at about 180° which are equipped with at least a part of said outlet holes, said central portion being substantially cylindrical.
Moreover according to an advantageous characteristic, said box body of the burner comprises an end distribution chamber placed at the closed end of said body and in fluid communication with said box wings.
Moreover according to an advantageous characteristic the central portion ends, immediately before entering the chamber, by a converging portion with reference to the direction supplying the gaseous fuel mixture from the port to the chamber of the burner, preferably with a conical or frustum of cone shape.
Moreover according to an advantageous characteristic, the central portion is in fluid communication with box wings by means of slits inside the body.
The invention further relates to a cooking apparatus comprising an oven or a grill and a burner according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics and advantages of the present invention will be more apparent from the following description of some embodiments shown in the annexed drawings, in which:

FIG. 1 is an exploded view of one embodiment of the burner according to the invention;

FIG. 2 is a perspective view of the burner of FIG. 1;

FIGS. 3, 4 and 5 are a side, plan and back view respectively of the burner of the previous figures;

FIGS. 6 and 7 are a prospective and back view respectively of the burner of the previous figures in different arrangements;

FIG. 8 is a perspective view of the box body of the burner of the preceding figures;

FIG. 9 is a plan view of a variant of the box body of the burner according to the invention;

FIGS. 10 to 13 are plan views of variants of a flame reflector of a burner according to the invention;

FIGS. 14 to 21 are schematic side views of variants of a supplying/mixing port of a burner according to the invention;

FIGS. 22, 23 and 24 schematically are the arrangement of a burner in an oven compartment, FIGS. 22 and 23 being two plan views and FIG. 24 being a front elevation view in the direction of the front door of an oven.

FIGS. 25 and 26 are constructional details of the burner by cross-section view.

FIGS. 27 to 35 are constructional details of the area of the flame arc forming head of the burner according to the previous figures.

FIGS. 36 to 44 are different views of the area of the burner according to a variant embodiment where the flame arc forming head is composed of a separate element that can be clamped between the two half shells forming the burner.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

While the invention is susceptible of various modifications and alternative constructions, some preferred embodiments are shown in the drawings and will be described in details herein below.
It should be understood, however, that there is no intention to limit the invention to the specific disclosed embodiment but, on the contrary, the invention intends to cover all the modifications, alternative constructions and equivalents that fall within the scope of the invention as defined in the claims.
The use of “for example”, “etc.”, “or” denotes non-exclusive alternatives without limitation, unless otherwise noted.
The use “comprises” means “comprises, but not limited to”, unless otherwise noted.
Terms as “vertical” and “horizontal”, “upper” and “lower” (with no other indications) have to be read with reference to installed (or operating) conditions and with reference to the standard terminology in use in common speech, where “vertical” means a direction substantially parallel to that of the vector of the force of gravity “g” and horizontal means a direction perpendicular thereto.
With reference to FIGS. 1 to 5 they show an illustrative, not limitative, embodiment of a burner 1 according to the invention.
Generally the burner 1 comprises a hollow box body 2, in turn provided with at least one supplying port 21 intended to be supplied with a gaseous fuel mixture and outlet holes 22 intended to deliver said gaseous fuel mixture.
The hollow box body 2 is preferably made by coupling two half-shells (upper and lower one); the words “upper” and “lower” used herein relate to the burner 1 in the operating condition, that is fitted in the oven on the bottom wall or immediately beneath the top wall thereof (grill).
The box body 2 (and therefore the half-shells) has an elongated shape and has an upper and lower face; the body 2 as a whole has an elongated but substantially flat shape, integrating therein—even in the general exterior appearance—the two typical characteristics of tubular burners and flat burners respectively, known in prior art.
One end of the body 2 is equipped with the supplying port 21 which defines a passage for the fuel mixture entering the body 2.
The end of the body 2 opposite to the supplying port 21 on the contrary is closed, and in some embodiments it comprises a flame arc forming head not shown in details.
With the burner 1 in the mounted condition the junction plane between the two half shells is substantially parallel both to the bottom and/or floor and/or top wall of the oven and to the outer faces of the two half shells that therefore are parallel to each other. The two half shells are preferably tightly joined together by bending continuous peripheral flanges that then are riveted or drawn (not shown).
On at least one of the half-shells of the body 2 there are provided holes 22 extending as aligned and that allow the gaseous fuel mixture (gas/air) to be delivered for generating the flame.
In some variants (not shown) there is also provided a pilot burner immediately in front of and beneath the holes 22, to pilot the flame; such pilot burner—if any—is configured as a concave seat with the concavity opened upwardly (with reference to the operating condition) and surmounted by the holes 22, made preferably as one piece with one of the half-shells of the body 2.
The burner 1 optionally comprises also a perforated base 5 for fastening the burner to the bottom wall or top wall of the oven.
Still with reference to the box body 2 and to FIGS. 8 and 9, it has to be noted how it comprises a central portion 23 in line with the supplying port 21 and preferably substantially cylindrical.
From the central portion 23 two box wings 28,29 provided with the outlet holes 22 radially extend at about 180°.
The central portion 23 defines a channel for the passage of the gaseous fuel mixture that ends in an end distribution chamber 27 placed at the closed end of the body 2; the gaseous fuel mixture is supplied from the end distribution chamber 27 to the box wings 28, 29 and—therefore

- to the holes 22.

This arrangement guarantees said mixture to be evenly distributed inside the burner body and consequently to the outlet holes 22. In practice, this creates a central preferential passage for the gas/air mixture that supplies the holes 22 provided in proximity of the closed end of the box body 2 (that is the ones placed on the walls of the chamber 27) at a pressure equal to all the other holes 22 that are at a shorter distance from the port 21 (that is the holes 22 of the box wings 28,29), such to obtain a substantially even output through all the holes 22.
It has to be noted with reference thereto that the central portion 23 ends, immediately before entering the chamber 27, by a converging portion 231 (with reference to the feeding direction of the gaseous fuel mixture from the port 21 to the chamber 27).
Preferably downstream of the converging portion 231 (still with reference to the feeding direction of the gaseous fuel mixture in operation), there is provided a constant section portion 232.
Such arrangements provide for a particularly even output.
Inside the body 2 (not shown) the central portion 23 is preferably provided with two laterally opened slots, that put the central portion 23 in fluid passage contact with the box wings 28, 29; such slots substantially face the holes 22, such to improve the flame being even.
Now with reference to the description of other components of the burner 1, they comprise, among others, a duct 3 conveying or feeding the gaseous fuel mixture towards the box body 2.
Such duct 3 is provided—at least—with a delivering port 32 and with a supplying/mixing port 31.
The latter is in turn provided with at least a first aperture 34 for a nozzle injecting the fuel gas and at least one second aperture 35 for the intake of a gaseous comburent, such as air.
Characteristically the supplying port 21 of the box body and the delivering port 32 of the conveying duct 3 have a substantially circular cross-section and are fitted with each other in a freely rotatable manner.
Such fitting preferably do not require sealing means since generally, the pressure of combustion air and fuel gas mixture is lower in the area of the port of the burner than in the other areas thereof.
In some cases or when required, however, it is possible to provide sealing means that generate a tight fitting.
In substance, the coupling allows the conveying duct 3, in the condition fitted on the port 21, to rotate with respect to the box body 2, such to be arranged according to any angles, such as shown in diagrams of FIGS. 6 and 7, where the duct 3 takes the angle positions illustrated and shown by directions A, B and C; although only three directions A, B and C are shown—only by way of example—the duct 3 can be oriented such to be extended along all the intermediate directions, such as mentioned above, to cover preferably an arc of 360° (round angle).
That is to say the supplying/mixing port 31 of the duct 3 is free to move along a circumference having as the center the one of the port 21 (coaxial in the fitted condition with the delivering port 32).
This gives more versatility to the burner 1, since it is possible, during its installation in an oven, to easily orient the supplying/mixing port 31 till coupling it with a gas delivering point of the oven itself.
Optionally it is possible to provide devices fastening the coupling between duct 3 and body 2, intended to lock them together once the duct 3 is arranged in the preferred direction.
An example of such fastening devices is a ring collar with a screw (not shown) that surrounds and clamps the coupling area and locks the duct 3 in position.
In other solutions the fastening device comprises a through screw that, once tightened, locks the two parts.
Other similar solutions can be provided by the person skilled in the art without efforts and in an equal manner in the light of the teaching provided therein.
In the not limitative embodiment shown, the conveying duct 3 comprises an elbow 38 placed between the delivering port 32 and the supplying/mixing port 31.
Such elbow 38 has, depending on needs, different angles in different embodiments, however the angle of 90° is preferred as in the example of the enclosed figures.
It has to be noted, in this example, that a converging/diverging portion 39 is also provided that is arranged downstream the supplying/mixing port 31, with reference to a direction supplying the gaseous fuel mixture towards said box body 2.
Preferably the converging/diverging portion 39 has also a constant section portion placed between the converging portion and the diverging portion.
Such arrangement allows gas to be optimally mixed with combustion air.
Preferably the converging/diverging portion 39 is placed downstream the supplying/mixing port 31 and before the elbow 38, with reference to a direction supplying the gaseous fuel mixture towards the box body 2.
Thus it results that the injection of the gaseous fuel mixture in the body 2 occurs along an axis (or direction) that is substantially perpendicular to the one of fuel gas injection through the first aperture 34.
Several embodiments of the supplying/mixing port 31 are shown in the enclosed FIGS. 14-21 and denoted by 31A-31H.
The different embodiments are possible constructional variants of the venturi tube intended to optimize the efficiency of the venturi tube as regards the intake of the proper amount of air in order to meet the optimal stoichiometric ratio.
Such condition is opposed generally by the contingent dimensions of the oven and by the fact that in order to allow a proper intake of secondary air, specific distances are also imposed between gas delivering holes, therefore it is not always possible to provide sufficient dimensions, above all as regards length, of the venturi tube.
The embodiment of the venturi tube 31 b is the one with more primary air (a good venturi tube can provide 70% of stoichiometric air to the mixture). This is guaranteed by the long neck, that is the intermediate cylindrical portion between the initial narrowing and the end widening.
When space conditions are such to require the venturi tube to be dimensionally compressed, then depending on conditions and on the type of sustainable compromise it is necessary to modify the venturi tube such to be able to be as much close as possible to the theoretical technical specifications by acting on other form parameters. For example is it possible to act as an alternative or in combination on the width of air inlet slots, on the divergence angle of conical portions, etc. For example the venturi tube according to the embodiment 31 d has a divergence angle higher than the theoretical one. The divergence angle affects the mixing.
In other embodiments the duct 3 is straight and the elbow 38 is absent.
With reference again to the burner 1 as a whole, it comprises also a reflector 4 useful for conveying a flame produced, in use, from the combustion of the fuel mixture coming out from the outlet holes 22.
The reflector 4 is preferably formed by plate-like surfaces joined to each other such to form a curved surface whose concavity, in use, is arranged at the side opposite to the one coupled to the body 2, which is arranged in a central condition on the convex face of the reflector 4.
Several embodiments of the reflector 4 can be alternatively provided, and they are shown in the enclosed FIGS. 10-13 showing plan views.
With reference to FIG. 22, an oven compartment 220, schematized and shown in plan view, houses a burner 1 provided with a reflector 4. In order to indicate the constructional parts of the burner such figure uses the same reference numbers used for identical parts or parts having identical functions in the examples of preceding figures.
A duct 3 with an elbow 38 is joined to a gas injecting nozzle (not shown) provided on the bottom wall of the oven compartment. The nozzle is engaged in the supplying/mixing port 31 through an engagement hole 34 at the head end of the duct 3.
The burner is arranged with its longitudinal axis coinciding with the direction of entry and propagation of combustion air and gas mixture flow in the inner compartment of the burner.
Moreover the burner is centered with reference to the direction parallel to the bottom side of the oven compartment and with reference to the direction perpendicular to said bottom side. Such positioning can be obtained by configuring the dimension of the duct 3 in the manufacturing phase that substantially requires only the dedicated production of the duct 3, while leaving the burner 1 unchanged which can be the same also for other configurations or other dimensions of the oven compartment.
Moreover as it will be clear from FIG. 24 with reference to a particular example applicable also to that of FIG. 22, the gas injecting nozzle can be provided at a level closer to the bottom part of the oven, therefore the axis of the duct 3 is not coplanar with the axis of the burner 1, but the end portion from the elbow 38 to the supplying/mixing port 31 can be inclined upwardly or downwardly with respect to the burner.
According to a preferred embodiment, the burner is placed higher than the supplying/mixing port 31 and therefore than the fuel gas injecting nozzle. This is advantageous since the air inside the oven compartment is more cold in the lower area and therefore the oxygen density is higher with the sucked volume being equal. Moreover hot combustion gases tend to go up towards a discharge flue (not shown) and not to go down in the lower area of the oven, therefore the environment air of the oven in its lower area is less polluted by combustion gases and therefore, with the volume being equal, the percentage of oxygen is higher than in the upper area of the oven.
FIG. 24 schematically shows the arrangement in the vertical plane of the injecting nozzle 240 and of the supplying/mixing port of the duct 3.
FIG. 23 shows a variant, wherein the gas injecting nozzle is provided in the right side wall of the oven compartment, at the angle region connecting to the rear side of the oven. The burner 1 is placed in the center with reference to the direction parallel to the rear side of the oven and in the center with reference to the direction perpendicular to the first one, that is to the antero-posterior direction of the oven.
The duct 3 is substantially like the one of FIG. 22, but it has a straight portion between the supplying/mixing port 31 and the elbow that has a longer length it being adjusted to the distance of the central antero-posterior axis of the oven from the side wall.
Also in this case during the production phase, the burner 1 is always the same, while the personalization of the arrangement to oven dimensions, to the position of the injecting nozzle and to the orientation and position of the burner is given only to the duct 3 that can be easily and quickly produced also in large sizes on demand, without requiring to be kept in stock.
FIGS. 25 and 26 show a cross-section in an intermediate area of a burner 1 according to the present invention and the axial section in the closed end and of the opposite end of the burner respectively.
In the embodiment of FIGS. 25 and 26 the burner 1 according to the present invention comprises a pair of half shells, of which an upper half shell 101 and a lower half shell 102. The two half shells have an elongated shape and respectively have an upper face and a lower face substantially flat and, in the coupled condition, form a tubular body which also has an elongated but substantially flat shape, integrating, even in the general exterior appearance, the two typical characteristics of tubular and flat burners respectively.
Two corresponding ends 201, 202 of the upper half shell 101 and of the lower half shell 102 respectively are shaped in such a manner that, with the two half shells in the coupled condition, they automatically form a closure or a flame arc forming head. The opposite corresponding ends of the half- shells 1, 2 are truncated and are shaped in such a manner as to form the closing headpiece of the tubular burner body. The junction plane between the two half shells is substantially parallel both to the bottom and/or roof and/or top wall of the oven and to the outer faces of the two half shells 101, 102, that therefore are parallel to each other.
The two half shells are tightly joined together by bending continuous peripheral flanges 401, 402, that are then riveted or drawn such to form a channel (FIGS. 25 and 26) with an outer side wall opposite to the side wall of the upper half shell 101. This side wall has a row of holes 501 extending as aligned and that supply the gas/air mixture to the channel that forms the pilot burner for the flame.
Therefore, the pilot burner is made of one piece with the burner body. This avoids the need to provide a separate part and it overcomes all problems associated to its attachment to the tubular body. The pilot burner and the row of holes 501 have a substantially U-shaped extension, with the arched portion extending along the flame arc forming head, when present, and with the two stems ending substantially at the truncated ends 301, 302 of the two half shells. Each side wall of the upper half shell 101 has an additional row of holes 601 with a larger diameter, which are not present at the flame arc forming head and that form the main gas/air mixture outlet holes.
FIGS. 27 to 35 show how the two truncated ends 301, 302 of the two half shells 101, 102 are pressed together to form a flattened end section that automatically forms a flame arc forming head.
Thus it is possible to obtain tubular bodies and therefore burners of different lengths by simply cutting the two half shells 101, 102 to the desired length, and by pressing the truncated ends 301, 302 against each other giving to said ends a particular shape taking the function of the flame arc forming head without using closing elements, like in currently known tubular burners.
Said flattened end section has a certain length extension and it is later associated to a base 303 provided with a hole 103 for fastening the burner to the bottom or top wall of the oven. It shall be noted that the two side flanges 401, 402 of the two half shells are further riveted such to perfectly tight close the end side edges. It shall be also noted that the phase deforming the end section generates a plurality of transverse folds 403 for stiffening and sealing the truncated end of the tubular body.
According to a further characteristics each of the two half shells 101, 102 at the peripheral edge of the upper and lower face has a substantially U-shaped continuous groove corresponding to an inner U-shaped continuous recess 701, 702 of each of the two half shells 101, 102 respectively and whose arched section coincides with the flame arc forming head.
As is apparent from FIG. 26 the stems of each U-shaped recess 701, 702 end at a predetermined distance from the flattened and deformed end of the tubular body. Said two U-shaped recesses 701, 702 extend in staggered positions and the sum of the heights of said two recesses 701, 702 is lower than the distance between the two inner faces of the two half shells 101, 102, in such a manner as to form a continuous slot for the passage of the gas/air mixture in the direction transverse to the flow direction.
The two recesses 701, 702 also act as gas/air mixture conveying walls for an even distribution of said mixture inside the burner body and consequently to the outlet holes 501, 601. In practice this creates a central preferential passage for the gas/air mixture that supplies the holes provided at the flattened end of the tubular body at a pressure equal to all other holes that are at a shorter distance from the gas/air mixture inlet port 21 so as to obtain a substantially even output through the holes 501, 601.
Recesses 701, 702 substantially extend for the whole length of the central tubular part 23 of the body of the burner 1 as it is clear from FIGS. 1, 8 and 9 and they slightly end before the end corresponding to the port 21 that is composed of a tubular extension of the central portion of the body of the burner to which the duct 3 is connected.
FIGS. 27 to 35 show the area of the flame arc forming head for the burner according to the preceding figures. In this case, the flame arc forming head is made by molding a truncated end of the two half shells 101 and 102. The shape of the flame arc forming head approximately resembles the flame arc forming head according to FIGS. 27 to 35 however it is not made in the form of a separate element fastened to the end of the burner.
Particularly the end of the lower half shell 102 is shaped such to form a box head having vertical tabs perpendicular to the bottom side 202 of the half shell 102 denoted by 60 and 61. The corresponding end of the upper half shell 101 on the contrary is made thin against the bottom side of the end portion of the flame arm forming head of the half shell 102 and shaped such to have a end tab 62 intended to be arranged parallel to the end tab 61 of the end of the flame arc forming head of the lower half shell 102, while the side 201 adhering against the bottom surface 202 of the end of the flame arc forming head of the lower half shell 102 is shaped such to form two axial channels 63 extending symmetrically to the median longitudinal axis and that on one side communicate with the inside of the burner and on the other side lead to the outer side of the tab 62 with two funnel-like widenings 64 during the molding deformation, the upper half shell is shaped such to form two longitudinal side folds 65 that progressively get narrow and that are tightly clamped and are arranged besides the side tabs 60 of the end of the flame arc forming head of the lower half shell 102 such to create a channel of flame arc forming head for the gas.
The upper half shell 101 is further fastened in the part of the flame arc forming head to the end of the flame arc forming head of the lower half shell 102 by means also of two side tabs 67 that are bent about corresponding side tabs 66 of the end of the flame arc forming head of the lower half shell 102.
Moreover in a position coinciding with each other and staggered with respect to the axial channels 63 and to the end funnel-like widenings 64 the adherent bottom sides 201 and 202 of the upper half shell 101 and of the lower half shell 102 have two coinciding holes 68. The holes in the bottom wall 202 of the lower half shell 102 extend towards the bottom wall of the upper half shell 101 by two sleeves 69 that have an outer diameter smaller than the holes 68 in the bottom wall 201 of the upper half shell 101 and that in the molding phase are riveted externally against said side 201 to generate additional regions mutually fastening the two ends of the flame arc forming head of the two half shells 101 and 102.
By means of such arrangement, between the end tab 61 of the lower half shell 102 and the end tab 62 of the upper half shell 101 a channel is formed wherein gas can pass through the channels 63, and the funnel-like aperture 64 thereof distributes the gas in an almost even manner in the channel of flame arc forming head delimited by the tabs 61, 62 and laterally by the tabs 60 and, the flame propagates around the head end of the burner.
The tab 65 further forms at its end an aperture between the lower curvature region and the corresponding surface of the lower half shell 202 from which the gas flow of the flame arc forming head in the end area is enriched.
The opposite end of the burner can be made according to one or more of the variant embodiments shown in the preceding FIGS. 1 to 9. The making of the end of the flame arc forming head according to the embodiment of FIGS. 27 to 35 allows the fastening base 103 and the ignition tube element 130 to be made in a separate, cheap and easily fastenable manner.
Unlike what disclosed in the embodiment of FIGS. 1 to 9, the flame arc forming head 400 shown in FIGS. 36 to 44 is made by a so called integrated ignition tube 140 that in the FIGS. 1 to 9 is absent.
In this case the flame arc forming head 400 is an element separated from the two half shells 101, 102 of the burner and it is clamped therebetween upon forming the burner, that is upon the mutual crimping of said two half shells 101, 102. Moreover particularly the flame arc forming head is obtained from a metal sheet blank by bending and/or molding.
In the shown embodiment the flame arc forming head has a rectangular or anyway squared shape. A central flattened portion 240, like a plate, has two holes or recesses 340 that are separated from each other by a central axial groove 440, which ends into a transverse groove 540 delimited by an end wall 640 that extends centrally into a spout forming the ignition tube 140 that can also be omitted. The transverse groove 540 is formed by a thinning step in the flattened portion 240.
The flattened portion 240 is delimited at its sides by perpendicular flanks 740 which also end at a certain distance from the end wall 640 and substantially flush with the step of the flattened portion 240. A series of axial holes or channels 840 crosses the flattened portion from one side to the other. The axial through holes or channels 840 are formed at such a height that at one end they open into the transverse groove 540, whereas the other end opens into the opposite parallel edge of the flattened portion 240. Therefore the ducts or through holes 840 provide communication between the transverse groove 540 and said opposite end edge of the flame arc forming head.
The flanks 740, in an intermediate portion of their outer wall, have an axial groove 940 whereas fastening recesses 340 are provided also in the bottom area, or the fastening holes 340 extend through the thickness of the flattened portion 240. In both cases, the fastening holes or recesses 340 open onto the flattened portion side opposite to the ignition tube 140 in an elongated transverse tight fastening recess 1040.
As is apparent from the figures, the flame arc forming head is obtained by bending a metal sheet by molding process. The axial holes or channels and the median axial groove are obtained by prior formation of holes and grooves in the unbent metal sheet. The flame arc forming head obtained in this manner allows burners to be made with variable lengths with flattened ends to obtain a support base and to form an end closure.
Moreover the flattened portion has another tab on the face turned towards the ignition tube 140, at the edge delimiting the transverse groove 540. The tab 1140 is divided by the median longitudinal groove 440 and extends in a position above and at a certain distance from the flattened portion 240. The tab 1040 faces the opposite transverse edge of the flattened part 240 and forms a pocket for housing the transverse edge of the lower half shell 102 of the burner, forming a further means fastening the flame arc forming head to the burner by clamping it between the tab 1040 and the flattened part 240. The tab 1040 contemporaneously acts as stop wall for fitting the flame arc forming head 140 on the end of the burner and also allows the sealing effect to improve.
The flame arc forming head of this embodiment is designed to be fastened to the end of the burner body by fastening the metal walls thereof onto the surfaces of the flame arc forming head itself. These are shaped in such a manner as to penetrate the recesses or the holes 340 and the elongated transverse recess 940 and as to also overlap the flanks 740.
FIGS. 36 and 37 show the flame arc forming head 40 in the condition mounted and locked in the corresponding end of the burner body. In order to simplify the operations for positioning the flame arc forming head in the proper fitted position in the burner, while guaranteeing also a certain preventive retention force in position, as it is apparent in FIGS. 32 to 35, the end of the burner may be pre-shaped to correspond to the transverse section of the flame arc forming head from the edge through which it is inserted in the end of the burner substantially to the step 1140. This is obtained by keeping a flat shape of the end of the half shell 102 adherent to the face of the flame arc forming head 400 opposite to the ignition tube, and by profiling the end of the opposite half shell 101 adhering against the face of the flame arc forming head turned toward the ignition tube 140 in a complementary manner to the cross section of the flame arc forming head and namely such to form a slot for inserting the flattened part delimited at its sides by two grooves for insertion of the flanks 740.
Moreover as particularly cleat in FIG. 34, the surface of the half shell 102 which is designed to adhere against the face of the flattened part 240 of the flame arc forming head opposite to the ignition tube has a ridge 819 that is shaped corresponding to the recesses or to the holes 340 and to the transverse recess 1140. The opposite wall of the half shell 101 has two ridges 818 intended to engage the ridges 740 of the flame arc forming head that act as a sealing creating a sealing effect between 818 and 740.
One of the two half shells or both the half shells 101, 102 further have ribs 919 which delimit the portion in contact with the face of the flame arc forming head intended to rest thereon and this for positioning purposes and also in order to improve the sealing effect during the fastening process, by molding.
By means of the arrangements described above it is possible to provide a method of manufacturing the burner that is very advantageous. A process for manufacturing an oven or grill burner according to the present invention comprises the steps of:
forming an upper half shell and a lower half shell by cutting a metal sheet blank, by bending, drawing and trimming the contours and making the outlet holes for the gas air mixture in the upper half-shell;
crimping the two half-shells for creating the burner body contemporaneously forming the pilot burner and a flame arc forming head terminal at one end, the opposite end being truncated;
forming a air and gas mixture supplying port provided with a terminal for the connection of a gas/air mixture supplying duct;
Additional steps can include:
welding on the upper half shell fastening pins for the parabola reflector;
fastening the supporting base;
positioning the parabola/reflector on the upper half-shell;
positioning the mounting for the igniter and thermocouple on the upper half shell;
fastening the parabola/reflector and the mounting.
An alternative process that can be provided in combination with a flame arc forming head made separately and not obtained by simply bending the half shells of the burner comprises the following steps:
forming a upper half shell and a lower half-shell by cutting a metal sheet blank, by bending, drawing and trimming the contours and making the outlet holes for the gas air mixture in the upper half-shell;
crimping the two half shells for creating the burner body contemporaneously forming the pilot burner such to form a tubular burner body truncated at both the ends. tightly locking an end closing and/or flame arc forming head member at the truncated end of the burner body by fitting and mechanical compression deformation;
tightly locking a rectilinear or curved connection joint at the opposite truncated end of the burner body, by fitting and mechanical compression deformation;
welding the parabola reflector fastening pins on the upper half shell;
deforming a wall extension of the truncated end of one of the two half shells such to create a base fastening the burner;
positioning the parabola/reflector on the upper half shell;
positioning the mounting for the igniter and the thermocouple on the upper half shell;
securing the parabola/reflector and the mounting.
In combination with the above steps and parallel therewith there is provided to form the duct 3 by molding a metal sheet and finally the common step crimping the duct 3 to the port 21 of the burner 1.
While the invention has been described in connection with the above described embodiments, it is not intended to limit the scope of the invention to the particular forms set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the scope of the invention. Further, the scope of the present invention fully encompasses other embodiments that may become obvious to those skilled in the art and the scope of the present invention is limited only by the appended claims.

Claims

The invention claimed is:

1. An oven or grill burner comprising:

a hollow box-shaped body having a supplying port receiving a gaseous fuel mixture and outlet holes emitting said gaseous fuel mixture;

a conveying duct conveying the gaseous fuel mixture toward the box-shaped body, the box-shaped body having a delivering port and a supplying/mixing port provided with a first aperture for a fuel gas and a second aperture for a gaseous comburent; and

a reflector conveying a flame produced, in use, by combustion of the fuel mixture from the outlet holes,

wherein the supplying port of the box-shaped body and the delivering port of the conveying duct have a substantially circular cross-section and are connected to each other in a freely rotatable manner.

2. The over or grill burner according to claim 1, wherein a connection between the supplying port of the box-shaped body and the delivering port of the conveying duct is sealed.

3. The over or grill burner according to claim 1, wherein the supplying/mixing port of the duct is free to move along a circumference having a center of the supplying port as a center.

4. The over or grill burner according to claim 1, further comprising fastening elements that fasten the duct to the box-shaped body, causing the duct and the box-shaped body to be locked to one another after the duct is arranged along a preferred direction.

5. The over or grill burner according to claim 1, wherein the conveying duct comprises an elbow placed between the delivering port and the supplying/mixing port.

6. The over or grill burner according to claim 1, wherein the conveying duct comprises a converging/diverging portion) downstream of the supplying/mixing port, with reference to a direction supplying the gaseous fuel mixture towards said box-shaped body.

7. The over or grill burner according to claim 6, when depending on claim 5, wherein said converging/diverging portion is placed downstream of the supplying/mixing port and before said elbow with reference to a direction supplying the gaseous fuel mixture towards said box-shaped body.

8. The over or grill burner according to claim 1, wherein said box-shaped body comprises a central portion in line with said supplying port from which two box wings extend radially at about 180° equipped with at least a part of said outlet holes, said central portion being substantially cylindrical.

9. The over or grill burner according to claim 8, wherein said body comprises an end spreading chamber placed at a closed end of said body and in fluid communication with said box wings.

10. The over or grill burner according to claim 9, wherein the central portion ends, immediately before going in the chamber, by a converging portion with reference to an advancement direction of the gaseous fuel mixture from the port to the chamber.

11. The over or grill burner according to claim 8, wherein the central portion is in fluid communication with the box wings by slits inside the box-shaped body.

12. The over or grill burner according to claim 1, further comprising one or more walls inside the box-shaped body conveying the gaseous fuel mixture for a even distribution of said mixture inside the burner and accordingly to the outlet holes, each of such walls being composed of an inner profile or recess obtained by squeezing deformation and formation of a slot or groove on an outer face of at least one half shell;

said inner profile or recess having such a size or being arranged to form a slot transversely conveying, in a continuous or discontinuous manner, the gaseous fuel mixture from a central area of the burner to a peripheral area where there are provided the delivering holes for the gas mixture at least for a portion of their longitudinal extension; and

optionally, said recesses coinciding with an outer slot in proximity of a peripheral edge of an outer face of half shells of the burner.

13. The over or grill burner according to claim 12, wherein said recess extends at least partly in a staggered position to form a continuous slot for conveying the gaseous fuel mixture in a direction transverse to a flow direction.

14. The over or grill burner according to claim 12, wherein a flame arc forming head part is made as one piece with the box-shaped body by shaping and mutually crimping ends of the two half shells forming the burner, or wherein the flame arc forming head is composed of a separate element clamped between the ends of the two half shells forming the burner.

15. A cooking apparatus comprising:

an oven or grill having a burner according to claim 1.

16. A process for manufacturing an oven or grill burner according to claim 1 comprising:

forming an upper half shell and a lower half shell by cutting a metal sheet blank, by bending, drawing and trimming contours and making outlet holes for a gas air mixture in an upper half-shell;

crimping the upper and lower half-shells to create a burner body, contemporaneously forming a pilot burner and a flame arc forming head terminal at one end, an opposite end being truncated; and

forming an air and gas mixture supplying port provided with a terminal for a connection to a gas/air mixture supplying duct.

17. The process according to claim 16, further comprising one or more of the following steps:

welding, on the upper half shell, fastening pins for a parabola reflector;

fastening the supporting foot;

positioning the parabola reflector on the upper half-shell;

positioning a mounting for an igniter and a thermocouple on the upper half shell; and

fastening the parabola reflector and a mounting.

18. A process for manufacturing an oven or grill burner in combination with a flame arc forming head made separately and obtained by not simply bending half shells of the burner, comprising:

forming an upper half shell and a lower half-shell by cutting a metal sheet blank, by bending, drawing and trimming contours and making outlet holes for a gas air mixture in the upper half-shell;

crimping the two half shells for creating the burner body contemporaneously forming a pilot burner such to form a tubular burner body truncated at both the ends;

locking an end closing and/or flame arc forming head member at the truncated end of the burner body by clutching and mechanical compression deformation; and

locking a rectilinear or curved joint at the opposite truncated end of the burner body, by clutching and mechanical compression deformation.

19. The process according to claim 18, further comprising one or more of the following steps:

welding parabola reflector fastening bolts on the upper half shell;

positioning the parabola reflector on the upper half shell;

securing the parabola reflector and the mounting.

20. The process according to claim 18, further comprising the steps of:

forming a gas and air mixture feeding duct by molding a sheet metal blank; and

crimping the feeding duct to a port of the burner.