WO2011128831A1

WO2011128831A1 - Cooking appliance

Info

Publication number: WO2011128831A1
Application number: PCT/IB2011/051554
Authority: WO
Inventors: Gianluca Mattogno; Mario Barbarossa
Original assignee: Indesit Company S.P.A.
Priority date: 2010-04-13
Filing date: 2011-04-12
Publication date: 2011-10-20
Also published as: ITTO20100289A1; IT1399558B1

Abstract

The present invention relates to a cooking appliance (1) comprising a cover (2,2') and at least one burner (5A,5B,5C,5D), wherein said burner (5A,5B,5C,5D) comprises at least one flame divider (7Α,7Α') for a gas, of the type fitted with at least one perforated metal plate for the outflow of said gas, wherein said flame divider (7Α,7Α') is made as one piece with said cover (2,2'); the invention also relates to a method for manufacturing said cooking appliance.

Description

COOKING APPLIANCE

DESCRIPTION

The present invention relates to an improved household appliance according to the preamble of claim 1.

The invention also relates to a method for manufacturing said cooking appliance.

In the field of known cooking appliances, two main kinds can be distinguished: those equipped with traditional-type gas burners, and those equipped with gas burners comprising a gas flame divider fitted with a porous element, a fibrous element or a perforated plate.

The first type includes cooking appliances equipped with traditional burners fitted with a flame divider having a series of radial channels from which the gas comes out, thereby generating a flame crown extending radially from the flame divider.

The second typology, which has been developed more recently, includes those burners wherein the flame divider comprises a gas-permeable element such as a perforated metal plate, originating a flame that extends axially upwards (the so-called "carpet flame").

In general, in the present description and in the appended claims reference will genetically be made to a "gas" flowing out of the flame divider; it is understood that this "gas" is normally a mixture of methane (or, more in general, a similar fuel gas) and air (the so- called primary air).

One example of such burners is discussed in International patent application WO2007/036772 in the name of the present Applicant.

In this type of burners, the flame divider comprises a perforated plate resting on the burner cup and made integral therewith by a central screw-type fastening device, that is inserted into a housing hole of the flame divider and into a corresponding threaded hole of a retaining means; the latter is in turn made integral with the burner cup, e.g. by means of welding spots.

The burner is constrained or secured or laid onto the cover of the cooking appliance.

In the present description and in the appended claims, the term "cover" refers to that component, typically consisting of a pressed metal plate, which is used for delimiting the upper end of the cooking top. For this purpose, the cover features one seat (provided as a hole in said plate) for each burner, and the flame divider assembly (which comprises the flame divider) rests on said cover.

The cover must therefore be provided with a number of seats equal to the number of burners to be installed.

This type of arrangement, which is rather complex per se, is made even more delicate by the fact that the flame divider must be sealingly secured onto the burner cup in order to avoid any gas leakage in the interface area therebetween.

However, such a design suffers from a few drawbacks: in the first place, seats must be created for the burners on the cover, typically by subjecting a metal plate that constitutes the cover itself to chip-removal machining.

Still on the cover, other housings must be obtained to accommodate the pan support grids, so as to prevent them from moving accidentally when in use.

The term "pan support grid" refers, in the present description and in the appended claims, to that structure (usually made of metal) which is adapted to support the pans over the burners: these grids may have various shapes, e.g. a cross with multiple branches afferent to the burner, and are adapted to support the pans over the burners when cooking foods contained therein.

Moreover, a sealed coupling must be ensured between the flame divider and the cup by means of mechanic machining (milling, threading, welding), and the assembly construction is relatively complex (including parts such as a fastening device and retaining means). Some of these machining steps (especially welding) are difficult on metal sheets which are only a few tenths of millimetre thick (the thickness of the perforated plate is normally approx. one millimetre).

When the perforated plate is enamelled (e.g. to facilitate cleaning or to improve the aesthetic appearance thereof), the above-mentioned machining steps are even more complex, since it is necessary to avoid damaging the enamel.

Particularly delicate areas for this type of burner are the interfaces between the various parts of the flame divider assembly, and the connection between the latter and the cup: in these areas, in fact, there is a relatively high risk of gas leaks, and it is therefore necessary to ensure a tight seal. The present invention aims at providing a cooking appliance comprising a gas burner fitted with at least one flame divider with a perforated plate which overcomes the drawbacks of the prior art.

In particular, it is one object of the present invention to provide a cooking appliance of the above-mentioned type which can be manufactured easily without requiring complex machining work, which ensures no gas leaks, and which requires low production costs as weel as a small number of mechanic machining steps.

This and other objects of the present invention are achieved through a cooking appliance incorporating the features set out in the appended claims, which are intended as an integral part of the present description.

The general idea underlying the present invention is to provide a flame divider of the burner in one piece with the cover of the cooking appliance.

It is thus possible to create a cooking appliance made with a minimal number of parts, leading to substantial savings in terms of parts, machining work and production costs. An additional advantageous feature is that the tight seal between the flame divider and the burner cup is attained through a sealing sleeve that can be built simply by bending the cover around the area thereof that constitutes the flame divider.

Yet another advantageous feature is that the sealing sleeve is obtained by bending the metal sheet of the cover in a manner such that it also forms the seat for the pan support grids, thereby not requiring additional machining of the cover.

In this way, both the cover and the flame dividers are advantageously manufactured by using a simple and inexpensive metal sheet, which is appropriately drilled and bent in the flame divider area.

Another advantage relates to the fact that the surface can be cleaned easily and any fastening elements between the flame divider and the cover are not accessible to a user.

Further objects and advantages of the present invention will become more apparent from the following detailed description and the annexed drawings, herein provided by way of non-limiting example, wherein:

Fig. 1 is a plan view of a cooking appliance according to the present invention;

Fig. 2 is a perspective view of the cooking appliance of Fig. 1 ;

Fig. 3 is a sectional view of a portion of the cooking appliance of Fig. 1 ; Fig. 4 is a sectional view of a burner of the cooking appliance of Fig. 3;

Fig. 5 is a sectional view of a variant of the cooking appliance of Fig. 1 ;

Fig. 6 is a sectional view of a burner of the variant of Fig. 5;

Fig. 7 shows a detail of the variant of Fig. 5;

Fig. 8 is a sectional view of an alternative embodiment of the variant of Fig. 6.

Referring now to Figs. 1 and 2, there is shown a cooking appliance 1 according to the present invention.

It comprises a cover 2 on which pan support grids 3A,3B,3C,3D and four cooking points 4 are laid, each one of the latter being provided with one respective burner 5A,5B,5C,5D, as well as a control interface 90 through which the burners 5A,5B,5C,5D can be adjusted.

The cover 2 may be a perfectly flat surface or, advantageously, it may feature raised portions (obtained, for example, by drawing) where the burners 5A,5B,5C,5D are located, so as to facilitate the supply of secondary air to said burners and improve the combustion. Associated with each cooking point 4, there are at least one burner 5A,5B,5C,5D and a corresponding grid 3A,3B,3C,3D, on which pans are arranged when the cooking appliance 1 is in use.

The burner 5A comprises a cup 6A and a flame divider 7A, shown in Fig. 4; the other burners 5B,5C,5D are made in a similar way and will not therefore be described in detail.

The flame divider 7A comprises, in accordance with the foregoing, a perforated metal sheet portion that allows the gas coming from the cup 6A to flow out.

The flame divider 7A has a substantially circular plan shape, and the holes are located in an annular area adjacent to the outer circumference of the flame divider 7A itself.

To this end, the flame divider 7A comprises, in fact, a perforated plate preferably made of decarburised steel specific for enamel coating, in particular of the DC04ED or equivalent type, as defined by the EN 10209 standard.

If no enamelling is provided, the perforated plate is preferably made of AISI 304 steel.

The thickness of the plate of the flame divider 7A varies between 0.5 mm and 1.5 mm, preferably between 0.9 mm and 1.1 mm.

The holes allow the gas to flow from the inner region of the cup 6A of the burner 5A to the outer region where the flame is generated.

The diameter of the holes is preferably comprised between 0.5 mm and 2.0 mm, more preferably between 1.2 mm and 1.3 mm.

In general, the value of the diameter of the holes is determined as a function of the power to be obtained from the burner; the larger the holes, the greater the gas flow and therefore the maximum power through put of the burner 5A.

In this example, the arrangement of the holes is such that they preferably occupy an annular portion of the flame divider 7A, or anyway it is such as to ensure a homogeneous gas distribution around a circular crown, for better combustion heating homogeneity.

As an alternative, the holes may be evenly distributed over the whole surface of the flame divider or they may be distributed unevenly, e.g. denser at the periphery and less dense towards the centre, depending on specific requirements and on the shape and dimensions of the flame divider.

With reference to Fig. 3, and in accordance with the teachings of the present invention, the flame divider 7A is made in one piece with the cover 2.

The flame dividers and the cover are therefore a monolithic part made of one material, which may advantageously be the one referred to above.

More in particular, all burners, as shown in Fig. 3 for the two burners 5A and 5B only, have the respective flame dividers 7A and 7B made in one piece with the cover 2, so that the user sees a single surface without solution of continuity, except for the gas outflow holes.

The convex shape of the flame dividers shown in Fig. 3 is obtained by pressing the metal sheet that constitutes the cover 2, and the holes are drilled in said metal sheet as well.

Of course, it just must be pointed out that such a convex shape may alternatively not be provided, in which case the cover 2 will be straight at any cross-section and the flame dividers will be identifiable by the user with the holes thereof.

The invention allows the grids 3A,3B,3C,3D to be mounted in adherence to the cover 2, especially taking into account that such flame dividers generate a "carpet flame" that allows pans to be positioned at a reduced height above the flame divider compared to traditional flame dividers, wherein the generated flame is a "crown" flame.

As to the coupling between the flame divider and the burner cup, reference will now be made to Fig. 4.

There is shown the burner 5A only (the others being similar), which comprises the cup 6A and the flame divider 7A (as one piece with the cover 2).

This design immediately appears to be advantageously simpler than those known in the art, as previously described.

The cup defines a chamber 10A having a substantially truncated-cone shape open at the top towards the flame divider 7A, in which the gas supplied by the nozzle 1 1 A flows in operation.

The cup 6A comprises a raised edge protruding towards the cover 2, thus forming a circular coupling edge 12 A.

At the free end of the coupling edge 12A there is a sealing means 13 A, such as a silicone gasket or the like, which ensures a tight seal between the cup 6A and the cover 2 to prevent any gas leakage.

The diameter of the coupling edge 12A is greater than that of the cover 2 in the region thereof with the flame divider holes, and is preferably greater than the outwardly convex portion of the cover 2, so that the gasket 13 A rests onto the cover 2 in an region thereof having a straight cross-section, thereby ensuring a satisfactory seal in operation.

As an alternative, the gasket 13A may be applied directly to the bottom surface of the cover 2, and the cup 6A may be sealingly abutted against said gasket 13 A.

According to yet another variant, the gasket may be omitted, and a tight seal is ensured by suitably machining the interface areas of the cover and of the cup 6A, e.g. by grinding and/or coining the mating surfaces thereof.

In the assembled condition, as shown in Fig. 4, between the flame divider 7A and the cup 6A a toroidal chamber 13 is generated which is filled with gas coming from the hollow volume 10A.

It should be noted in this regard that in the example shown the diameter of the open mouth of the hollow volume 10A is substantially equal to or slightly smaller than the central diameter with no holes of the flame divider 7A, whereas the toroidal chamber 13 abuts on the flame divider portion with holes.

This is useful mainly to ensure a uniform gas distribution through the holes: in fact, the gas comes from the hollow volume 10A and flows towards the flame divider 7A; it then meets the non-perforated central diameter of the flame divider 7A and is thus deviated into the toroidal chamber 13, from where it is finally let out through the holes that face said toroidal chamber 13.

Fig. 5 shows a variant of the cooking appliance described so far.

In this variant, by suitably shaping the cover around the flame divider it is possible to attain a better coupling with the burner cup while avoiding the use of a gasket.

In Figs. 5 and 6, the same reference numerals followed by an apex (') designate the same parts, which will not be described any further.

Referring now to Fig. 5, there are shown the flame dividers 7A' and 7B', made in one piece with the cover 2', surrounded by a sealing sleeve 14A', also made in one piece with the cover 2', which for this purpose is drawn into the desired shape.

The sealing sleeve 14A' therefore comprises a concave side, facing outwards from the cooking appliance 1, and a convex side jutting out from the cover 2' towards the cup, i.e. facing the opposite direction.

The sealing sleeve 14A' extends all around the flame divider 7A'.

In the assembled condition (i.e. the one shown in Fig. 6), the sealing sleeve 14A' is coupled to the coupling edge 12A', so as to provide a stable engagement between the cup 6 A' and the cover 2'.

Said coupling is preferably obtained by interference, thereby ensuring both a good mechanical coupling and a tight seal, necessary for preventing any gas leaks in this area. The sealing sleeve 14A' comprises two vertical wall sections VI and V2 jutting out towards the cup and joined by a bottom section F, as shown in Fig.7.

The vertical walls may adhere to each other, or the metal sheet drawing may be such that they remain at a certain distance from each other.

In this latter case, the concave portion of the sealing sleeve 14A' advantageously houses the base portion of the pan support grids 3, for which no dedicated seats will therefore be needed on the cover 2'.

One particularly advantageous embodiment of this design is shown in Fig. 8, wherein the same reference numerals followed by two apexes (") designate the same parts, which will not be described any further.

In this case, the end of the sleeve 14A" has a truncated-cone cross-section with the major base towards the flame divider and the minor base towards the cup 6A".

The latter 20 has a circumferential engagement channel 17A" that houses the end portion of the sleeve 14A".

The engagement channel 17A" has a truncated-cone cross-section, with the major base towards the flame divider and the minor base facing the opposite direction.

The perimetric walls V1 ",V2" of the sleeve 14A" are not parallel to the inclined walls 18A", 19A" of the engagement channel 17A"; on the contrary, the opening angle of the former with respect to a vertical axis is more acute than that of the latter: thus, in the coupled condition two circular sealing lines are generated between the sleeve and the cup. Said two sealing lines advantageously improve the tightness of the seal obtained in that interface area.

Moreover, if the cover 2", and hence the sleeve 14A", is made of a harder material than the cup (e.g. sheet-metal or, more in general, steel for the former and aluminium for the latter), it can be foreseen that during the assembly stage the cup will get slightly deformed with respect to the sleeve so as to conform to the latter, thereby further improving the sealing between the two parts.

A cooking appliance 1 according to the present invention may comprise one or more burners, even of different size, shape or type.

A cooking appliance typically comprises four burners, as in the case shown herein, one of which has a standard size, two are bigger "fast" burners, and another one is an "ultrafast" burner which is even bigger.

The idea underlying of the present invention is applicable to cooking appliances equipped with one or more burners.

Moreover, a cooking appliance according to the present invention may also comprise, in combination with the above, one or more traditional burners or electric heating plates or the like.

It is apparent that many changes may be made to the present invention by those skilled in the art without departing from the protection scope thereof as stated in the appended claims.

For example, it is conceivable to provide a flame divider comprising a plate having holes obtained over the whole free surface, or anyway having configurations other than annular, e.g. double annular or star configurations.

The method for manufacturing such a cooking appliance according to the present invention comprises the following steps:

a. preparing a metal plate;

b. drilling said metal plate in order to obtain one or more flame dividers;

c. applying a burner cup to the perforated area, so as to obtain a gas burner.

Advantageously, the method may also comprise the step of:

d. drawing said metal plate in order to create a sealing sleeve 14 A',

carried out between said steps b and c or between said steps a and b.

As an alternative to or in combination with the above, the method may further comprise the step e. of associating a gasket with said cup and/or with said cover at the interface therebetween.

Furthermore, although reference has been made in this description to a preferred embodiment consisting of a sheet-metal cover 2, this component may be made of different materials as well, not necessarily metallic ones.

Thus, for example, there may be cooking appliances wherein the cover 2 with the flame divider holes is made of materials that can be machined by pressing or moulding, such as glass, ceramic, glass-ceramic, gres or even marble.

It is apparent from the above description that the present invention attains optimal results in terms of easiness of cleaning and aesthetic appearance of the cooking top, in particular of the cover thereof.

Claims

1. A cooking appliance (1) comprising a cover (2,2',2") and at least one burner (5A,5B,5C,5D), wherein said burner (5A,5B,5C,5D) comprises at least one flame divider (7A,7A',7A") for a gas, of the type fitted with at least one perforated sheet for the outflow of said gas,

characterised in that

said flame divider (7A,7A',7A") is made as one piece with said cover (2,2',2").

2. A cooking appliance (1) according to claim 1 or 2, wherein said perforated sheet is provided at least with gas outlet holes having a diameter between 0.5 mm and 2.0 mm, preferably between 1.2 mm and 1.3 mm.

3. A cooking appliance (1) according to claim 1 or 2, wherein said burner (5A,5B,5C,5D) further comprises a cup (6A,6A',6A") sealingly coupled with said cover (2,2',2").

4. A cooking appliance (1) according to claim 3, wherein said cup (6A,6A',6A") comprises a coupling edge (12A,12A',12A") protruding towards said cover (2,2'), which is adapted to ensure said sealed coupling with said cover (2,2',2").

5. A cooking appliance (1) according to claim 4, wherein a free end of said coupling edge (12A) facing said cover (2) is associated with a sealing means (13A), such as a gasket or the like, and wherein said coupling edge (12A) is coupled with a portion of said cover (2) within a region thereof having a straight cross-section.

6. A cooking appliance (1) according to claim 4, wherein said cover (2') comprises a sealing sleeve (14A',14A") made as one piece with said cover (2',2"), and wherein said sleeve extends around said flame divider (7A',7A") and is adapted to sealingly engage with said coupling edge (12A',12A") of said cup (6A',6A").

7. A cooking appliance (1) according to claim 6, wherein said sealing sleeve (14Α') comprises a convex side jutting out from said cover (2') towards said cup (6 A') and a concave side facing the opposite direction.

8. A cooking appliance (1) according to claim 6 or 7, wherein said sleeve (14A") comprises, at least in one end portion thereof, a truncated-cone section with the major base towards said flame divider, and wherein said cup (6A") comprises a circumferential engagement channel (17A") adapted to house, in the assembled condition, an end portion of the sleeve (14A").

9. A cooking appliance (1) according to claim 8, wherein said engagement channel (17A") comprises a portion having a truncated-cone cross-section with the major base towards said flame divider, and wherein said sleeve (14A") comprises inclined perimetric walls (V1 ",V2") having an opening angle relative to a vertical axis which is more acute than that of inclined walls (18A",19A") of said engagement channel (17A").

10. A cooking appliance (1) according to one or more of claims 7 to 9, comprising at least one pan support grid (3A,3B,3C,3D) housed at least partly on said concave side of said sealing sleeve (14A¹).

1 1. An appliance according to any one of the preceding claims, wherein the sheet (2) comprises a metal plate.

12. An appliance according to any one of the preceding claims, wherein the sheet (2) is obtained from materials such as glass, ceramic, glass-ceramic, gres or even stone.

13. A method for manufacturing a cooking appliance according to one or more of claims 1 to 1 1 , comprising the following steps:

a. preparing a metal plate;

b. drilling said metal plate in order to obtain one or more flame dividers in a perforated area;

c. applying a burner cup to the perforated area, so as to obtain a gas burner.

14. A method according to claim 13, further comprising the step of:

d. drawing said metal plate in order to create a sealing sleeve (14Α'),

carried out between said steps a and b or between said steps b and c.

15. A method according to claim 13 or 14, further comprising the step of:

e. associating a gasket with said cup and/or with said cover at the interface therebetween.