WO2015033298A1

WO2015033298A1 - Oven muffle with guides fixed therein

Info

Publication number: WO2015033298A1
Application number: PCT/IB2014/064275
Authority: WO
Inventors: Fabio Gambardella; Matteo Scoponi
Original assignee: Indesit Company S.P.A.
Priority date: 2013-09-09
Filing date: 2014-09-05
Publication date: 2015-03-12
Also published as: EP3044517A1; ITTO20130731A1

Abstract

The invention relates to a muffle (1) of a food-cooking oven, comprising a plurality of walls (2-6) circumscribing a cooking cavity, at least one guide (7) for supporting grids, dripping pans or similar oven items, which can be positioned inside the cooking cavity and bound to a respective vertical wall (2,3,4), binding means (74,75) for binding the guide (7) to the vertical wall (2,3,4), wherein said binding means comprise at least one magnet (75).

Description

Title:

"OVEN MUFFLE WITH GUIDES FIXED THEREIN"

The present invention relates to a muffle of a food-cooking oven.

As is known, the structure of a muffle of an oven for household use, or anyway intended for cooking food, comprises profiled guides for supporting grids/dripping pans where food to be cooked or warmed is placed.

These guides are normally positioned along the internal lateral walls of the muffle, and are made out of metal wires suitably shaped and joined, preferably by electric welding. The typical structure of one of such guides comprises two stay rods joined together by means of pegs, the latter being preferably arranged in close pairs. In this way, it is possible to position the edges of the grids and/or dripping pans between the pairs of pegs of the guides, so that said grids/dripping pans can be held in a raised position relative to the bottom of the muffle.

In these prior-art guides, at least one end of at least one of the two stay rods is bent in such a way as to form a curl (also referred to as eyelet), into which a screw can be engaged which, since it also engages into a threaded pawl fixed to the side wall, makes it possible to firmly bind the guides to the muffle.

The pawl is preferably fixed to the outer face of the side wall of the muffle, and communicates with the inside of said muffle through a hole in the side wall; it should be noted that the presence of the hole inevitably weakens the structure of said muffle.

The system for fixing the guides to the muffle does not allow them to be easily decoupled from said muffle, because a user wanting to remove them, e.g. in order to wash them, will need at least one screwdriver or another suitable tool.

When using a screwdriver or another tool in a confined space like the inside of a muffle, there is a high risk of damaging the latter, because it is difficult for a human operator to engage the screwdriver, and keep it engaged, with the screw head. As a matter of fact, it is very likely that the screwdriver or another tool, should it miss or slip off the screw head, will rub its tip along the side wall of the muffle, thereby damaging the surface of the inner face of the latter. This surface, in fact, is normally coated with a thin layer of refractory material that might be easily damaged by the tip of a screwdriver or another tool.

Moreover, there is a risk that the thread of the threaded pawl might be damaged (stripped) by improperly inserting the screw and/or by applying thereto an excessive tightening torque.

It is one object of the present invention to overcome these drawbacks; in other words, the aim is to provide a muffle comprising at least one guide, which can be coupled to the inner walls of the muffle without requiring the use of screws, pawls or other similar items, which would make the guide mounting/dismounting operations complex and risky for the integrity of the inner surfaces of the muffle.

The basic idea of the present invention is to fix the guide to the muffle by means of at least one magnet.

The features of the present invention will be specifically set out in the appended claims. These features as well as further advantages of the present invention will become more apparent from the following description of an embodiment thereof as shown in the annexed drawings, which are supplied by way of non-limiting example, wherein:

Fig. 1 is a perspective view of a muffle according to the invention;

Fig. 2 is a perspective view of the detail A of Fig. 1;

Fig. 3 is a perspective view of the detail B of Fig. 1;

Fig. 4 is a front view of the muffle of Fig. 1;

Fig. 5 is a view along the section C-C of Fig. 4;

Fig. 6 is a view along the section D-D of Fig. 5;

Fig. 7 is a view of the detail F of Fig. 6;

Fig. 8 is a view along the section E-E of Fig. 5;

Fig. 9 is a view of the detail G of Fig. 8.

With reference to Fig. 1, a muffle 1 according to the invention comprises a pair of side walls 2,4, a back wall 3, a bottom 5 and a top wall 6, which delimit a cooking cavity or chamber.

On the inner face of each one of the vertical walls 2,3,4, preferably of the side walls 2,4 only, at least one guide 7 can be positioned. These guides allow positioning at least one grid 8 and/or at least one dripping pan (not shown in the annexed drawings) inside the muffle 1.

Also with reference to Fig. 2, the guides 7 have a ladder-like structure and comprise two stay rods 71 and at least one pair of pegs 72 that join together said stay rods 71.

Each pair of pegs 72 preferably comprises an upper peg 72a and a lower peg 72b arranged close to each other, so as to form a seat into which at least a part of the edge of the grid 8 and/or of the dripping pan can be engaged. The man skilled in the art may use guides having a peg shape and/or configuration other than the one just described (e.g. only the lower peg, on which the grid 8 and/or the dripping pan can be laid), without however departing from the teachings of the present invention.

Also with reference to Figures 3 to 7, at least one of the stay rods 71 comprises a hook 73 positioned at the upper end of said stay rod 71, the term "upper end" identifying that part of the stay rod 71 which, when the guide 7 is in an operating condition (i.e. coupled to the side wall 2,4), is closest to the top wall 6 of the muffle 1.

This hook 73 has such a shape that it can be engaged into a hole 21,41 for hanging the guide 7 on the side wall 2,4.

In the preferred embodiment, each guide 7 comprises two hooks 73, whereas the side walls 2,4 comprise two holes 21,41, for a better distribution of the load transferred from the guides 7 to the side walls 2,4.

In order to advantageously prevent the side walls 2,4 from undergoing excessive deformation, the holes 21,41 are located within protuberances 22,42, wherein said protuberances 22,42 preferably have their concavities facing towards the inside of the muffle 1, wherein such protuberances 22,42 can be obtained by cupping the side walls 2,4 by means of a punch acting from the inside towards the outside of the muffle 1. The configuration of these protuberances 22,42 allows the load acting upon the guides 7 to be discharged in a manner such that the deformation of the side walls 2,4 will show a concavity facing towards the outside of the muffle, so that the side walls 2,4 will tend to get closer to each other. In this way, the side walls thus deformed will push the guides 7 closer to each other, thereby advantageously improving the stability of a grid 8 and/or dripping pan positioned between said guides 7.

In addition to the above, and also with reference to Figures 8 and 9, each one of the guides 7 also comprises binding means that, in turn, comprise at least one curl 74, also referred to as eyelet 74, and at least one magnet 75 set into said curl 74.

The curl 74 is preferably located at the lower end of the stay rod 71, wherein the term "lower end" identifies that part of the stay rod 71 which, when the guide 7 is in an operating condition (i.e. coupled to the side wall 2,4), is closest to the bottom 5 of the muffle 1.

In order to advantageously facilitate the positioning of the magnet 75 into the curl 74, the magnet 75 has a shape that comprises a central cylinder 75b and two peripheral cylinders 75a,75c, wherein said cylinders 75a,75b,75c are all coaxial to one another, and wherein the central cylinder 75b has a smaller diameter than both of the peripheral cylinders 75a,75c. Furthermore, the peripheral cylinders 75a,75c may advantageously have different diameters, so that the one with the bigger diameter 75a can act as a stop, while the one with the smaller diameter 75c can act as a spreader upon the curl 74.

When the magnet 75 thus configured must be coupled to the curl 74, the smaller peripheral cylinder 75c is abutted on the curl 74 and a force 75e is applied to the bigger peripheral cylinder 75a (see vector in Fig. 9), so that the curl 74 will be elastically deformed by the cylinder 75c until the side surface of the curl 74 comes in contact with the side surface of said cylinder 75c. When the cylinder 75c comes out of the curl 74, the latter will narrow, returning into its initial shape and coming in contact with the central cylinder 75b. The movement is then stopped by the peripheral cylinder 75a, which, having a bigger diameter, will not be able to spread the curl 74. In order to decouple the magnet 75 from the curl 74, it will be necessary to exert a force 75f on the cylinder 75c (see vector in Fig. 9), which, by spreading the curl 74, will allow the magnet 75 to come out of said curl 74.

The man skilled in the art may also use a magnet having a different shape than the one described above, without however departing from the teachings of the present invention. When the guide 7 is in an operating condition, the magnet 75 stays in contact with the inner face of the side wall 2,4 to which said guide 7 is coupled, thereby ensuring a stable positioning of the guide 7. This is possible because the side wall 2,4 is at least partly made of a ferromagnetic material, preferably a metal or a metal alloy, so that the magnet 75 will exert an attraction force towards said side wall 2,4. It must be pointed out that the inner face of the side wall 2,4 may be coated with a thermally insulating layer (not shown in the annexed drawings), preferably a ceramic one, having a thickness of a few tenths of a millimeter. This material must however allow the magnet 75 to interact with the ferromagnetic material under said thermally insulating layer, so as to allow the magnet 75 to be attracted by the side wall 2,4. In addition, also the magnet 75 may be coated with a layer of protective and/or thermally insulating material useful for improving its service life, but said material must only minimally affect the magnetic field generated by said magnet 75.

In the preferred embodiment, each guide 7 comprises two curls 74 and two respective magnets 75, so as to ensure a more stable coupling between each guide 7 and the respective inner face of the side wall 2,4 of the muffle 1.

For the purpose of improving the positioning of the magnet 75 with respect to the inner face of the side wall 2,4, each side wall 2,4 may comprise at least one, preferably two, cavities 23,43 with their concavities facing towards the inside of the muffle 1, wherein such cavities 23,43 can be obtained by cupping the side walls 2,4 by means of a punch acting from the inside towards the outside of the muffle 1.

As the guide 7 is coupled to the side wall 2,4, this cavity 23,43 acts as a draft seat for the magnet 75, which, being attracted by said wall 2,4, will be positioned into the cavity 23,43, thereby centering the guide 7 in its operating position and compensating for a possible inaccurate positioning by the user and/or taking up any play; to this end, the shape of the cavity 23,43 must be compatible with that of the magnet 75.

The magnet 75 is made of a material, preferably iron or an alloy thereof, having a Curie temperature higher than the temperature that can be reached inside the muffle 1 during the normal operation of the oven (about 200-300 °C), so as to ensure that the magnet 75 will always generate a substantially constant magnetic field.

When using this embodiment of the invention, it is possible to remove the guides 7 from the muffle 1, together with the magnets 75, before the execution of a pyrolysis cycle in the muffle, during which temperatures around 500 °C will be reached. It will thus be advantageously possible to employ magnets having a Curie point between the normal operating temperature of the oven (200-300 °C) and the temperature at which pyrolysis will occur (approx. 500 °C).

In summary, in order to place one of the guides 7 into an operating position (guide 7 coupled to the side wall 2,4), the user of the oven comprising the muffle 1 according to the invention must first engage the hooks 73 into the holes 21,41 of the side wall 2,4 to which the guide 7 is to be coupled, and then bring the magnets 75 near the cavities 23,43 up to a point where the magnets are attracted by the side wall 2,4; in order to decouple the guide 7 from the side wall 2,4, the user must exert a force on the lower part of the guide 7 (the one closest to the bottom 5 of the muffle 1) towards the inside the muffle 1 (perpendicularly to the side wall), e.g. by pulling a pair of pegs 72 towards the inside of the muffle, so as to separate the magnets 75 from the side wall 2,4, after which the user will disengage the hooks 73 from the holes 21,41.

In a first variant of the invention, at least one hook 73 of the preceding embodiment is replaced with the above-described binding means, i.e. a magnet 75 set into a curl 74, positioned at the upper end of at least one of the stay rods 71. This variant requires a reduced number of holes in the side walls, thus increasing the strength of the wall and/or ensuring better energetic efficiency. In fact, by reducing or eliminating the holes 21,41 it is possible to reduce the heat that will be lost from the muffle 1 in operation by dissipation through the hook(s) 73.

In a second variant of the invention, at least one of the magnets 75 is not set into the curl 74, but is attached to the inner face of the side wall 2,4 of the muffle 1 or is set into said side wall 2,4, so as to advantageously allow the use of a different type of guide, other than the above-described guide 7. This also allows the use of guides not prearranged for using these binding means.

The only requirement that the guides employed in this variant must fulfill is that they must be made of ferromagnetic material.

Furthermore, in this variant the magnet may also be set into a hole already present in the side wall 2,4 and/or located outside the cooking cavity of the muffle 1, so as to allow the use of the above-described binding means in a muffle according to the prior art, by replacing the pawl(s) with one or more magnets 75.

In a third variant, a guide 7 can be applied to the back wall 3 of the muffle 1 by using the above-described binding means and solutions, thus making it possible to also engage the rear edge of the grid 8 and/or dripping pan when the latter is (are) in a (cooking) operating position inside the muffle 1.

It must however be pointed out that, although in the examples shown in the drawings and in the above-mentioned variants the guides 7 are applied by using magnetic binding means 74, 75 to vertical muffle walls 2, 3 4 (the latter being the side walls or the back wall of the muffle), the principles of the invention are also applicable to guides resting on horizontal muffle walls, e.g. the bottom one.

For example, the magnets may be associated with the lower end of the guides 7, which rests on the horizontal bottom wall (as opposed to the vertical side wall) of the muffle or on the curved connection area between the bottom wall and the side wall.

Nevertheless, this and other equivalent variants will still fall within the scope of the following claims.

Claims

1. Muffle (1) of a food-cooking oven, comprising

- a plurality of walls (2-6) circumscribing a cooking cavity,

- at least one guide (7) for supporting grids, dripping pans or similar oven items, which can be positioned inside the cooking cavity and bound to a respective wall

(2,3,4),

- binding means (74,75) for binding the guide (7) to the wall (2,3,4),

characterized in that

the binding means comprise at least one magnet (75).

2. Muffle (1) according to claim 1, wherein the wall (2,3,4) is at least partly made of ferromagnetic material.

3. Muffle (1) according to claim 2, wherein the guide (7) comprises at least one first eyelet (74) into which the magnet (75) is set.

4. Muffle according to claim 3, wherein the guide (7) comprises a first (71) and a second stay rod (71) and at least one pair of pegs (72) extending between said stay rods

(71), wherein said first eyelet (74) is positioned at one end of the first stay rod (71).

5. Muffle according to claim 4, wherein at least one of the stay rods (71) comprises a hook (73) positioned at the upper end of said stay rod (71), wherein said hook (73) is so shaped that it can be engaged into a hole (21,41) comprised in the wall (2,3,4) in order to hang the guide (7) on the wall (2,3,4).

6. Muffle (1) according to any one of the preceding claims, wherein the wall (2,3,4) comprises a cavity (23,43) adapted to act as a draft seat for the magnet (75), which, being attracted by said wall (2,3,4), is positioned into the cavity (23,43), thereby centering the guide (7) in an operating position.

7. Muffle (1) according to any one of claims 4 to 6, wherein the guide (7) comprises a second eyelet (74) and a second magnet (75) set into said second eyelet (74), which is positioned at one end of the second stay rod (71).

8. Muffle (1) according to claim 7, wherein the guide (7) comprises a third eyelet (74) and a fourth eyelet (74), into which a third (75) and a fourth magnet (75) are respectively set, wherein said third (74) and fourth eyelet (74) are respectively positioned at opposite ends, with respect to the first (74) and second eyelet (74), of the stay rods (71).

9. Muffle (1) according to any one of the preceding claims, wherein the guide (7) is at least partly made of ferromagnetic material.

10. Muffle (1) according to claim 9, wherein the magnet (75) is coupled to the wall (2,3,4) of the cooking chamber.

11. Muffle (1) according to claim 10, wherein the magnet (75) is set into the wall (2,3,4).

12. Muffle (1) according to claim 10 or 1 1, wherein the magnet (75) is positioned outside the cooking chamber.

13. Muffle according to any one of the preceding claims, wherein the wall (2, 3, 4) whereon the binding means (7) act is substantially vertical.

14. Food-cooking oven comprising a muffle (1) according to any one of claims 1 to 13.