EP1257771B1

EP1257771B1 - Counter-door frame with gasket for domestic cooking ovens

Info

Publication number: EP1257771B1
Application number: EP00909625A
Authority: EP
Inventors: Bruno Cuocci
Original assignee: G I A T SpA; Giat SpA
Current assignee: Giat SpA
Priority date: 2000-02-22
Filing date: 2000-02-22
Publication date: 2004-12-01
Anticipated expiration: 2020-02-22
Also published as: TR200201953T2; PL356298A1; EP1257771A1; DE60016468T2; WO2001063181A1; AU2000231903A1; DE60016468D1; PL196577B1

Description

The present invention relates to a counter-door or muffle frame for domestic cooking ovens, provided with an elastomeric sealing gasket.

Elastomeric gaskets are known, adapted to provide a seal all around the muffle of cooking ovens, which have metallic inserts with hooks protruding through slits (GB patent 2106974) or slots formed in the gasket by removal of material (European patent No. 0277098 of the same applicant). The protruding, substantially hook-shaped portion of said metallic inserts is brought into corresponding holes formed in the abutment surface of the oven door. Only with the second of the two above-mentioned patents the danger is prevented of rips or tearings being formed in the gasket, due to the contact between metal and elastomeric material, while also the application of adhesive in correspondence with each insert can be avoided or is substantially reduced.

However, from the economic point of view it must be considered that the introduction of the inserts into the gasket during the manufacture of the latter greatly affects the costs which weigh upon the final manufacturing cost of the oven, the manufacturer not being able to reduce to zero the handwork necessary for mounting the gasket, which anyway requests anchoring in the holes suitably formed around the muffle frame.

It is also known from European patent 0096745 to provide tongues projecting from the counter-door surface, so as to form the anchoring points of a gasket showing along its whole length a continuous transverse slit for housing said tongues. However this solution, which could be considered corresponding to the preamble of claim 1 of the present application implies also a few drawbacks. First, it is to be noted the indefinite positioning of the gasket with respect to the anchoring points and the non-uniform stretch which can therefrom result, in addition to the danger of tearing of the gasket contacting the edges, often cutting, of the tongues which are simply made by cutting the plate and raising the cut portion.

Therefore, object of the present invention is providing an assembly of counter-door and gasket for doors of domestic cooking ovens which does not have the above mentioned drawbacks, which are typical of the known anchoring systems obtained by working of the same counter-door surface, and on the other side requests less work to be made by the gasket manufacturer, resulting in a lower assembly cost.

These objects are obtained by an assembly of counter-door and relevant gasket having the features of claim 1 and in particular the fact of having the end portions of the anchoring points being suitable for insertion into corresponding slots made by removal of material from the gasket, thus ensuring a definite positioning of the gasket itself while avoiding its possible tearing or cutting.

In fact, it has been possible to verify that in this case, the additional costs of the gasket will comprise, besides those for extruding the section, only those for carrying out the slots by die-cutting, while saving the metal inserts and the insertion thereof in the gasket through said slots. On the other side, the oven manufacturer will have to carry out the preparation of the anchoring seats, which will be obtained by providing a single suitable die, as well as the mounting of the gasket thereon. However, it is easily understood that die amortization and handwork burden for putting the gasket onto the relevant seats will never equal the increased cost of the complete gasket provided by the gasket manufacturer, to which anyway it had to be added the burden of the oven manufacturer to provide for anchoring in the counter-door associate holes of the metal inserts already fitted in the gasket.

A further advantage consists in that, with the assembly according to the present invention, there is no more the need for separated pieces such as the metal inserts which the gasket manufacturer, normally expert in rubber extrusion, was obliged to have produced by third parties and to keep in a storehouse before assembling them with the rubber section.

Further objects, advantages and features of the present invention will appear from the following detailed description of one preferred embodiment thereof, given as a non-limiting example with reference to the accompanying drawings, wherein:

figure 1 shows a frontal view of an example, according to the present invention, of an assembly of counter-door for domestic cooking oven, that is of a muffle frame with relevant gasket, where the door (not shown) is intended to abut, wherein the gasket is shown with dotted lines;

figure 2 shows a perspective view of a comer portion of only the frame or counter-door of figure 1 which shows in a greater detail one of the elements, made thereon, for anchoring the gasket, here not shown;

figure 3 shows, in a bigger scale than figure 1, a comer portion of the gasket mounted on a oven counter-door, not shown; and

figure 4 shows a sectional view, along line IV-IV, of the gasket of figure 3, mounted on a corresponding counter-door portion as shown in figure 2.

With reference to the drawings, with 1 is shown a frame of a muffle 10 of a domestic oven, traditionally with four sides which enclose the oven internal space 11, closed by a door (not shown) suitable to abut, by closing, against the frame 1 on which a sealing gasket 2 is mounted, normally made of rubber, preferably of the silicone-based type, having a traditional cross-sectional shape with longitudinal internal chamber 9 and, in the upper part, sealing wing with or without a further chamber 9a (see figure 4). In figure 1, the gasket is shown by means of dotted lines of which the external pair of lines schematically represents the two side feet which are normally present in this kind of gasket, which continuously extend in all their length so as to improve the sealing to the anchoring surface, while the above mentioned wing is useful for improving the sealing against the door, thus preventing fumes and vapors from coming out from the oven. In the representation of figure 1, the left side of the drawing relates to a three-sided gasket ending with an end 6, while at the right side thereof a four-sided gasket is assumed, which is imagined to continue beyond the line of interruption of the drawing in the central zone, being closed by a head junction which is not shown.

According to the present invention, frame 1 is provided, at every comer, with a gasket anchoring member 3, better shown in figure 2. In a preferred embodiment which is here represented, said member 3 is formed by means of partial cutting or half-cutting and drawing of the plate which forms the counter-door. The cutting lines, the full external one 5 and the partial internal one 6, are curved, preferably with homologous bend, both having the same bending center represented with O in figure 2, and their ends are connected to each other by a curve whose radius is notably smaller than the bending radius of

lines

5 and 6. Along line 6, the cutting is provided only on two terminal, mutually symmetric segments, leaving the continuity of the plate along a central arch CD, internal to arch AB between the ends of the cutting. With a drawing operation, the curved strip 7 of the plate included between

lines

5 and 6, is raised so as to be parallel to the plane of frame 1 and joined to this by a substantially perpendicular segment 8 which extends along said arch CD, thus conferring to the anchoring seat or member 3 substantially the shape of an L in cross-section, as shown in figure 4.

It can be assumed that angle AÔB equals the muffle comer (generally of 90° as shown in the figure, but not necessarily, when non-rectangular muffles are used), while angle CÔD is smaller than this. At every member 3, gasket 2 is provided with a slot 4 obtained by removal of material. Insertion is carried out by introducing one end of member 3 into the internal chamber of the gasket, inserting it into the slot until it contacts segment 8. At the same time, at the other end, member 3 has to be completely penetrated into the slot and is convenient that the latter, at the end of the insertion, be in contact with the vertical ends of segment 8, without clearance, in order to prevent movements once in function, but also avoiding stresses which could, in time, cause tearings. Therefore, it is preferred that the length of slot 4 indicated with L be equal to the length of segment 8, that is, of arc CD. By indicating with CÔD the corresponding angle, it must be: L = 2R π / 360, wherein R is the bending radius of line 6 of partial or internal cutting. While angle AÔB, relevant to the whole member 3, substantially copies the corresponding angle of the frame or counter-door comer, almost always of 90°, angle CÔD, having a smaller size, can be for instance of 60° or 70° according to the maximum effort accepted for inserting the gasket or removing the same when dismounting.

For example, assuming a radius R of 20 mm, to an angle CÔD f 60° corresponds an extension in length L of the slot of about 20mm. In the hypothesis of an angle AÔB of 90°, the overall length of member 3, that is of the cutting, is about 31 mm. Therefore, the lengthening that the slot must undergo in order to enable insertion will be such as to bring it to a length corresponding to arch AD that is CB, therefore equal to 31-20 / 2, that is about 5-6 mm. This is equivalent to a percentual lengthening, with respect to the initial 20 mm, of about 30%, absolutely bearable by the elastomeric materials which are presently on the market. If, on the contrary, angle CÔD is narrower, the requested stretch would be higher, for instance equal to about 90% for an angle of 35°, still assuming that the total angle of the insertion seat is 90°. With angles even more reduced, the drawn and not cut segment 8 would be too short, resulting in a too weak plate portion for resisting above all to the strength due to the thrust exerted by the closing door and due to the hinge springs, which could determine the deformation thereof.

On the other side, if the drawn and not cut segment 8 would extend for almost the whole length of line 6, leaving only one end length of member 3 spaced from the plane of frame 1 which is too short, that is with a minimum difference between angles AÔB and CÔD, the operation of insertion of the gasket could be difficult because of the insufficient extension of the end lengths inserted therein and which form the fitting anchoring members of the gasket.

With reference to figure 1, it is worth while noting that the described assembly of frame and gasket can be applied both in the case of a four-sided gasket, closed as a ring with head junction, and in the case of a three-sided gasket. In fact, as represented in figure 1, on the drawing left side the gasket can be interrupted just after the anchoring zone, in 12, without particular differences with respect to the case, exemplified on the right side of figure 1, wherein the gasket has been previously closed as a ring by a head junction.

Claims

A counter-door frame (1) for domestic cooking ovens, with a coupling zone for an elastomeric rubber gasket (2) at every comer of the frame, every one of said coupling zones being provided with a curved coupling section (3), which is contiguous with and protruding from said frame (1), having in cross-section substantially the shape of an L and comprising a strip of plate (7) extending along an arc (AB), spaced and substantially parallel to said frame (1), characterized in that each strip (7) has end portions being suitable for insertion into corresponding slots (4) made by removal of material from said gasket (2) and is spaced from the frame and joined thereto by means of a substantially perpendicular segment (8) which extends along an arc (CD) having a smaller length than said arc (AB), symmetrically to the latter, said arc-shaped elements (7, 8) of the coupling section (3) forming in cross-section the sides of said L.
A counter-door frame and gasket assembly according to claim 1, characterized in that said segment (8) of coupling section (3) is joined to said frame (1) along a curved line (6) substantially corresponding to arc (CD), the bending center (O) of which being coincident with that of an external curved line (5) along which said strip (7) is separated from said frame, said curves (5, 6) being connected to each other at the ends with bends whose radius is sensibly smaller than the bending radius (R) of the lines (5,6) having center in O.
A frame and gasket assembly according to claim 2, characterized in that said slot (4) formed in the gasket has a length (L) substantially equal to the length of said arc (CD), so as to be arranged, during use, with the longitudinal ends thereof in contact, without mechanical stresses, with the terminal edges of said perpendicular segment (8).
A frame and gasket assembly according to claim 3, characterized in that, for an angle (AÔB) of said cutting line (5) of about 90°, the angle (COD) corresponding to said junction segment (8) along said line (6) is of about 60°-70°, whereby a lengthening of the length L of the slot (4) of about 30% is obtained, when inserting the coupling section (3) into gasket (2).