The present invention relates to oven muffles comprising a muffle wall with a mounting region for a fan and a cover element for said mounting region, wherein a plurality of through-holes is provided in the perimeter of the mounting region for insertion of connection bolts, wherein the cover element comprises a plurality of lugs comprising openings which overlap the through-holes of the muffle wall, and wherein the lugs project from the cover element towards the muffle wall so as to maintain the cover element at a distance of the muffle wall. The present invention further relates to ovens comprising such oven muffles.

In ovens, particularly in convection ovens, fan ovens or hot air ovens, typically a fan is provided in the rear wall of the oven muffle so as to circulate hot air within the interior cavity of the oven muffle so as to heat food products.

An oven muffle and oven respectively of the generic type is disclosed in EP 1 464 898 A1. A similar concept is known from DE 10 2004 047 993 A1 and in DE 10 2006 004 348 A1.

A common problem in such conventional ovens is that if, as is typically the case, the fan cover is made of sheet metal which is provided with a protective enamel coating, providing for the required distance between the muffle wall and the cover element is difficult to achieve, In particular, if such distance is to be provided by the shape of the cover element, and in particular by the shape of the lugs, this often leads to surface geometries which are difficult to enamel. Thus, if, for example, the lugs are provided in cup-shaped bulges of the sheet material of the cover element, which bulges often are employed due to their stability, providing for a sufficient distance between the cover member and the muffle wall requires a rather deep cup, in which, in order to provide for an enamel coating, more enamel is required than for the remaining surface areas of the cover element.

It is an object of the invention to provide an oven muffle, in which the above problems are solved, and in particular, to provide an oven muffle which is easier to manufacture.

In an oven muffle as it is defined in the pre-characterizing portion of claim 1 the above object is solved in that each of the through-holes provided in the muffle wall comprises a lug which projects towards the cover element, wherein the lug of the cover element and the lug of the muffle wall abut at their projecting surfaces and wherein the lug of the cover element and the lug of the muffle wall have substantial the same extension in a plane essentially parallel to the muffle wall at the location of the lugs.

In this manner the distance, which is required between the cover element and the muffle wall has not to be provided by the shaping of only the lugs provided at the cover element, as in conventional oven muffles, but rather said distance is maintained by a first lug provided at the cover member, which lug cooperates with a second lug which is provided at a corresponding location at the muffle wall. In other words, rather than providing for each connecting element, as it is used for connecting the cover member to the muffle wall, a single steep projection, in accordance with the present invention such projection is replaced by two shallow projections, one of which is provided at the cover member and the other one of which is provided at the muffle wall.

Due to the shorter distances, which have to be spanned by the individual projections provided at the cover member and at the muffle wall, the required distancing function can be implemented with shallower and smoother surface geometries which are easier to manufacture than those used in prior art muffles.

Preferred embodiments of the present invention are defined in the dependent claims.

In particular, the lugs of the cover element comprise generally cup-shaped bulges, which provides for a higher stability.

Similarly, also the lugs provided at the muffle wall preferably comprise generally cup-shaped bulges which project towards the cover element.

In order to provide for a design of the oven muffle in which the fan and fan cover project into the muffle cavity only as much as is required to provide for an efficient air circulation within the muffle cavity, the muffle wall in the mounting region preferably comprises a recess for accommodation of the fan impeller.

The muffle wall further can comprise in said mounting region at least one recess for accommodation of a heating element that is used in operation of the oven to heat air to be circulated through the oven muffle by the fan impeller.

In addition to the air outlets which are provided by maintaining the cover element at a distance to the muffle wall, the cover element further can comprise in its central region one or more vent openings so as to direct an air stream towards the central region of the oven muffle.

Preferably the muffle wall and/or the cover element are made of sheet metal, which further can be provided with an enamel coating so as to provide for corrosion and oxidation resistance and to facilitate cleaning of the oven muffle. Alternatively, other materials and/or protective coatings could be used, such as ceramic coatings or coatings with other high-temperature resistive materials such as Teflon or the like.

In an oven which comprises an oven muffle in accordance with the present invention, a fan is attached to the muffle wall such that the fan impeller is located within the mounting region. As in conventional ovens this can be accomplished by mounting a motor for driving the fan at the rear side of the muffle wall and providing in the muffle wall a through-hole through which the motor shaft projects, wherein the fan impeller then is attached onto the motor shaft.

In the mounting region of the muffle wall there further can be provided one or more heating elements, such as a ring-shaped heating element which is located to be arranged about the surface region of the muffle wall which is overlapped by the fan impeller.

A preferred embodiment of the present invention will be described below by reference to the drawings, in which:

Fig. 1

is a top view of a cover member made in accordance with the present invention;

FIG. 2

is a sectional view of the cover member of FIG. 1 through a lug as indicated in FIG. 1 at line 2-2;

FIG. 3

is a top view of the region of a muffle wall where a fan is to be mounted;

FIG.

4 is a sectional view of the cover member of FIG. 3 through a lug as indicated in FIG. 3 at line 4-4;

FIG. 5

shows the cover member of FIG. 1 when mounted to the muffle wall shown in FIG. 3; and

FIG. 6

is a sectional view in the region of a lug as indicated at line 6-6 of FIG. 5.

Cover element 10 shown in FIG. 1 has a generally rectangular shape and comprises an elevated central region 12 which bulges out from a peripheral edge region 14 and comprises a circular central region 16 behind which, in the mounted state, there will be located a fan impeller of an oven muffle within which fan cover 10 is mounted.

Cover element 10 is mounted to a muffle wall 22, such as the rear wall of an oven muffle, by means of connection bolts 36 (see FIG. 5), such as screws, rivets or the like, which are inserted through-openings 18 provided in lugs 20, which in the embodiment shown in FIG. 1 are located in the corner regions of rectangular cover element 10.

As can be seen in FIG. 2, lugs 20 comprise generally cup-shaped depressions, which are formed into the cover element 10, which in the embodiment shown in FIG. 1 is made of a metal sheet material and which has been shaped by deep drawing.

FIG. 3 shows a portion of a muffle wall 22 and in particular the portion of a rear wall of an oven muffle where a fan is to be located. Mounting region 24 has a generally rectangular shape in the center of which there is a shallow circular depression 26, in which in the assembled state of the oven the impeller of a fan will be located. In order to drive such impeller, a motor is mounted at the rear side of muffle wall 22 so that the motor shaft extends through an opening 28 in the center of circular depression 26. In the embodiment shown in FIG. 3, muffle wall 22 further comprises an annular depression 30 for accommodating a ring-shaped heating element.

For fixation of cover element 10 at muffle wall 22, four through-holes 32 are provided in the mounting region 24 of muffle wall 22 at locations which correspond to the locations of openings 18 of cover member 10. Through-holes 32 are arranged within lugs 34, a sectional view of which is shown in FIG. 4.

As shown in FIG. 4, lugs 34 comprise cup-shaped depressions of the sheet material provided in mounting region 24, which depressions project from muffle wall 22 towards cover element 10.

FIG. 5 shows cover element 10 when mounted in the mounting region 24 of muffle wall 22. During mounting, cover element 10 was lined to mounting region 24 of muffle wall 22 so that the openings 18 of lugs 20 overlap openings 32 of lugs 34 provided in muffle wall 22. Then, connecting bolts which preferably provide for a releasable connection of cover element 10 and muffle wall, such as screws 36, only one of which is shown in FIG. 5, are inserted through holes 18.

As can be seen in FIG. 6, which is a sectional view along line 6-6 of FIG. 5, when cover element 10 is mounted to muffle wall 22, lug 32 of muffle wall 22 cooperates with lug 20 of cover element 10, so as to maintain distance between cover element 10 and muffle wall 22, so that air can be directed from under pass cover element 10 along muffle wall 22 to the muffle cavity. In addition, in the embodiment shown in FIGS. 1 and 5, cover element 10 is provided in its central region 16 with a plurality of vent openings 38.

In contrast to conventional oven muffles in which projecting lugs were provided only at the cover element, and the through-holes provided in the muffle wall for insertion of connecting bolts where provided in a flat section of the muffle wall, so that in such conventional oven muffles the entire distance between the cover element and the muffle wall had to be provided by the lug of the cover element, in the oven muffle suggested herein much shallower lugs can be employed, which facilitates manufacturing of the oven muffle.