EP2840320B1 - Oven with self-cleaning inner surface in its oven chamber - Google Patents

Description

The invention relates to a furnace having a furnace muffle with a self-cleaning inner surface.

There are ovens of the type in question, in which an inside of the oven muffle is provided with a self-cleaning coating. This self-cleaning coating is porous, so that dirt, especially fats, can penetrate into the pores. In the pores, the fat is degraded at sufficiently high temperature as they occur during operation of the furnace. This can be done for example in the so-called. "Ecolysis" characterized in that the self-cleaning coating contains by their porous structure numerous oxygen storage, which support the degradation. In the ecolysis, temperatures of about 270 ° C are sufficient to eliminate impurities in the oven muffle.

In normal operation of the oven, the self-cleaning layer takes up most of the soils, e.g. during the Ecolyse also including Wrasens, from the limited by the oven muffle cooking space. These contaminants are mostly degraded at normal operating temperatures. However, especially with very large amounts of fat, it can happen that the self-cleaning layer becomes oversaturated with fat and thus loses its function. In such a case, a separate cleaning cycle must be initiated by a consumer at a sufficiently high temperature. This allows the self-cleaning layer to reduce all pollution and thereby restore its self-cleaning ability. However, it is difficult for the end user to know when such a cleaning cycle is needed. Such recognition is made more difficult by the fact that the self-cleaning layers are deliberately color-adjusted so that soiling and its possible residues are difficult to see, e.g. black.

The document US Pat. No. 3,783,853 A1 describes an oven having at least one bottom wall, two sidewalls and a back wall made of embossed metal with an enamel layer, thereby enhancing the catalytic function.

The document DE 80 20 039 U1 describes a baking oven muffle whose inner surfaces are coated with a catalytically self-cleaning coating.

The document DE 25 07 659 A1 describes a stove with a baking muffle and arranged in the baking muffle sheets, which are provided with a catalytic self-cleaning layer.

The document DE 73 18 690 U describes a roasting and baking apparatus whose inner side walls of the muffle are provided with a catalytically effecting the self-cleaning layer.

It is the object of the present invention to overcome the disadvantages of the prior art at least partially overcome and in particular to provide an improved way to detect a supersaturation of a self-cleaning inner surface of a furnace muffle.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

• der vermindert selbstreinigungsfähige Teilbereich so ausgebildet ist, dass er einen optischen Vergleich mit einem voll selbstreinigungsfähigen Teilbereich ermöglicht und
• der mindestens eine vermindert selbstreinigungsfähige Teilbereich an einer Prallwand angeordnet ist.

The object is achieved by a furnace, comprising a furnace muffle with a self-cleaning inner surface, wherein at least a visible portion of the inner surface is at least reduced self-cleaning ability and wherein the self-cleaning ability of the reduced self-cleaning portion is still given,

• the reduced self-cleaning portion is designed so that it allows a visual comparison with a fully self-cleaning subsection and
• the at least one reduced self-cleaning portion is disposed on a baffle.

As a result, soiling is typically left on the surface of these reduced self-cleaning subregions, which are absorbed and decomposed at the remaining, fully self-cleaning subregions. Thus, a user can make a visual comparison between the reduced self-cleaning subregions with the fully self-cleaning subregions, providing a readily recognizable indicator of the degree of fouling. With a slight contamination after a cooking process, only small amounts of oils, fats, etc. will settle on the less self-cleaning areas, so that an optical difference will also be low. With a larger contamination after a cooking process, larger quantities of oils, fats, etc., will settle on the less self-cleaning areas, which are visually easily recognizable. For example, a fat layer remaining on a reduced self-cleaning portion may have a brownish-yellow color, while a fully self-cleaning portion absorbs the fat (though it can no longer fully decompose) and appears black, for example. Consequently, a customer, having clearly recognized a color change of the at least one less self-cleaning portion, can start a cleaning cycle. Unnecessarily carried out cleaning cycles can be omitted and otherwise corresponding energy can be saved. In addition, the presence of a supersaturated self-cleaning layer can be avoided by insufficient cleaning cycles. The customer is not burdened with extra effort by cleaning the entire inside of the oven muffle by hand. The oven can operate in a particularly energy-efficient manner thanks to the cleaning cycles performed at the right time.

It is a development that the oven is an oven, a microwave oven or a combination thereof, in particular in conjunction with at least one further cooking function such as a steam cooking function.

The oven is in particular a household oven, so a household appliance with a furnace functionality.

The oven muffle typically has a front loading opening which is closable by an oven door. The inner surfaces of the oven muffle and the oven door define or limit a cooking chamber. The cooking chamber can also be referred to as a furnace room or as a treatment room for food.

According to the invention, at least one visible partial region is arranged on a baffle wall (also called a hot air baffle). This results in the advantage of a particularly simple detection of saturation, as often occurs on the baffle the highest amount of fat or oil in a cooking chamber. The baffle can be regarded as an independent component of the furnace muffle or as part of a side wall of the cooking chamber, in particular as part of a rear side wall or rear wall.

The fact that a sub-area is less self-cleaning means that there is still a self-cleaning ability there.

In another case, which is not part of the invention, a partial area, which is less self-cleaning, also mean that there is no self-cleaning ability is given, so the sub-area is not or no longer self-cleaning.

It is a development that the self-cleaning inner surface is or has a self-cleaning layer or layer which receives its self-cleaning ability by Ecolyse. It is still a further development that the self-cleaning inner surface is or has a self-cleaning layer or layer which receives its self-cleaning ability through catalysis. In catalysis, in particular, a catalyst used to reduce soils may be bound in the self-cleaning layer.

The self-cleaning layer or layer may, for example, comprise porous ceramic, e.g. as a catalytically coated base body. However, the self-cleaning layer or layer may also have inorganic particles bonded.

In particular, a partial area which can be viewed by a customer through a feed opening of the oven muffle can be understood as a visible partial area. A visible partial area may in particular be arranged on at least one side wall of the oven muffle, since a particularly high level of fat accumulation is to be expected there. In this case, the visible partial area may be present in particular on a lower half, which facilitates its visibility for an operator or user.

It is an embodiment that the self-cleaning inner surface has a self-cleaning layer with a first pore volume and the at least one reduced self-cleaning portion has a reduced self-cleaning layer with a second, reduced pore volume. The lower pore volume reduces self-cleaning ability and tends to deposit e.g. of fat on the (outer or free) surface of the reduced self-cleaning portion reinforced. In particular, an average pore volume per unit area of the partial area can be understood as a pore volume.

It is still an embodiment that the reduced self-cleaning portion is a compacted portion, which thus has a lower porosity or pore density. Such compaction can be achieved, for example, by means of a local pressure treatment and / or heat treatment of a previously unreduced self-cleaning starting material at the site of the reduced self-cleaning subregion to be produced. Due to the lower porosity, for example, the absorption capacity for oxygen, which allows for ecolysis, or a catalytically active surface sink. The compression can in particular lead to a compact partial area or a partial area with a negligible porosity.

It is a further embodiment that the reduced self-cleaning portion is a portion with at least partially filled by means of a filling pores. This also causes a lower porosity or pore density. The filler may be, for example, glass. For example, the self-cleaning layer may be locally infiltrated with liquid glass.

It is yet another embodiment that the reduced self-cleaning portion is a portion of reduced thickness. Although the porosity or pore density is retained, the absolute pore volume decreases, in particular in relation to a reduction in the layer thickness. Also, it reduces the ability to degrade soils, especially grease or oil. The reduced thickness may be e.g. be achieved by material removal processes.

It is yet a further embodiment that the reduced self-cleaning partial area is a partial area with partially extensive or complete removal of the self-cleaning layer. This subarea thus has at least one subarea without the self-cleaning layer and at least one subarea with an undiminished self-cleaning layer. Although averaged over the subregions, there remains a porosity or pore density of the subregion, but the absolute pore volume decreases compared to an unremovable self-cleaning subregion by the partial removal of the self-cleaning layer. Also, it reduces the ability to degrade soils, especially grease or oil. The removal of the layer may be e.g. be achieved by material removal processes.

As a shape of a subregion without the self-cleaning layer, various patterns and shapes are possible. Thus, a further development is that at least one subregion, in particular the at least one subregion without the self-cleaning layer, forms a regular pattern. For example, the regular pattern may be a line pattern of multiple lines. The line pattern may be e.g. a stripe pattern with a plurality of mutually parallel lines or a grid pattern with a plurality of parallel and mutually perpendicular lines. Also, e.g. a hole pattern, e.g. with matrix-like holes, or a checkerboard pattern used.

It is still a further development that a resolution of the at least one of the subregions is so high that a viewer looking into the cooking chamber from outside the cooking chamber can no longer visually resolve the subregions and the subregion thus represents an optically uniform region. As a result, one observer may, for example, create the visual impression of a different color of this subregion in comparison to the untreated surrounding layer.

It is also an embodiment that the reduced self-cleaning portion is sealed against a cooking chamber enclosed by the oven muffle. Thus, although the porosity and the pore volume at least largely retained, but the impurities can no longer penetrate into this subregion.

It is also an embodiment that the reduced self-cleaning portion can be provided by means of a laser machining of an undiminished self-cleaning starting material. Such a processing is particularly easy to carry out, especially on an initially fully self-cleaning inner surface, and also precise and flexible without great effort with respect to a form of at least one reduced self-cleaning portion.

It is also an embodiment that at least one reduced self-cleaning subregion has a shape of at least one character string, e.g. each having at least one symbol, at least one letter and / or at least one number. This allows a customer a suitable time of a cleaning cycle are presented particularly catchy.

It is an embodiment that the at least one less self-cleaning subregion has a form of user information. This allows the customer to see a "speaking" message. The user information may in particular represent a text, e.g. "clean now".

It is also an embodiment that at least one optical comparison surface is provided, in particular on the oven muffle, in particular next to the reduced self-cleaning portion. The optical comparison surface makes it possible in a particularly simple manner to optically balance the degree of soiling of the reduced self-cleaning portion with a predetermined threshold value. The optical comparison surface may in particular have a surface which has a predefined, non-changing color. This predetermined color may in particular correspond to a color of the reduced self-cleaning portion at a predetermined contamination threshold, from which a separate cleaning cycle is recommended. Achieving the pollution threshold is by this design particularly simple and accurate by color comparison of the reduced self-cleaning portion and the optical reference surface possible. The optical reference surface need not have a self-cleaning ability.

In the following figure, the invention will be described schematically with reference to an embodiment schematically. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity.

The Fig. Shows in a view obliquely from the front of a household oven 1 with a furnace muffle 2, which front or front has a feed opening 3. The feed opening 3 can be closed by a - not shown - oven door. The oven muffle 2 defines, with the closed oven door, a cooking chamber 4. The oven muffle 2 has a bottom 5, a left side wall 6, a right side wall 7, a rear side wall (rear wall) 8 and a ceiling 9. The rear side wall 8 has here as part of a baffle 12, which serves as a cover of an attached behind fan and / or ring heating (o. Fig.) And as a baffle. The oven muffle 2 has or the walls 5 to 9 have a self-cleaning inner surface 10. The self-cleaning inner surface 10 is formed by a porous, catalytic or ecolysis-capable, self-cleaning layer with a first pore volume V1.

On the left-side side wall 6, possibly on the right-hand side wall 7 and on the baffle 12, in each case in a lower half, there are several easily visible by a customer sections 11 of the inner surface 10, which are not or only slightly self-cleaning. This reduced self-cleaning capability is here effected purely by way of example by a locally reduced, second pore volume V2 of less than V1, e.g. by means of laser processing, filling with glass, etc. Alternatively, the subregions 11 may be e.g. be sealed against the cooking chamber 4 or be reduced in thickness. The sections 11 are shaped in the form of letters which each form the message "CLEAN NOW".

At the reduced self-cleaning portion 11 of the left side wall 6 a color-predetermined optical reference surface 13 is provided here, the one facilitates color matching with the sub-area 11 for determining a pollution threshold.

After a cooking process, at the beginning of the oven muffle 2 had been cleaned, 2 impurities, especially fat, have deposited on the inner surface 10 of the oven muffle. These contaminants are usually broken down by the self-cleaning portions of the inner surface 10, but at least partially remain at the reduced self-cleaning portions 11. At a low contamination during cooking, especially at a low level of fat, the portions 11 will be little dirty, in particular be covered only slightly with grease and thus not color or only slightly different from the rest, self-cleaning inner surface 10. A customer or user will thus not be able to clearly recognize the subareas 11 and receive no indication of activation of a cleaning cycle.

By contrast, with a very high amount of fat, the liquid fat will penetrate into the pores of the self-cleaning-capable subareas of the inner surface 10, but can not be completely degraded there during this cooking process. There is a supersaturation. At the reduced self-cleaning portions 11 now forms a superficially clear brownish-yellow greasy film, which differs in color from the rest, self-cleaning inner surface 10, which is usually black. Consequently, a customer or user clearly recognizes the words "CLEAN NOW" and will then activate a separate cleaning cycle. The detection of the appropriate time for performing the separate cleaning cycle is significantly facilitated by a color comparison of a portion 11 with the reference optical surface 13. The optical comparison surface 13 may for example have a brownish-yellow color.

In this cleaning cycle, for example, the cooking chamber 4 without food to be heated to a temperature which allows the self-cleaning (eg to 270 ° C or more), so that in the self-cleaning areas of the inner surface 10 residual fats are degraded.

Of course, the present invention is not limited to the embodiment shown.

Generally, "on", "an", etc. may be taken to mean a singular or a plurality, in particular in the sense of "at least one" or "one or more" etc., unless this is explicitly excluded, e.g. by the expression "exactly one", etc.

Also, a number may include exactly the specified number as well as a usual tolerance range, as long as this is not explicitly excluded.

LIST OF REFERENCE NUMBERS

1

Household oven

2

muffle furnace

3

loading port

4

oven

5

Bottom of the oven muffle

6

left side wall

7

right side wall

8th

back sidewall

9

blanket

10

self-cleaning interior surface

11

Subareas with reduced self-cleaning ability

12

baffle wall

13

optical comparison surface

V1

first pore volume

V2

second pore volume

Claims (10)

1. Oven (1), having an oven chamber (2) with a self-cleaning inner surface (10), wherein at least one visible subarea (5, 11) of the inner surface (10) has reduced self-cleaning capability and wherein the self-cleaning capability of the subarea (5, 11) with reduced self-cleaning capability is also provided, characterised in that

   - the subarea (5, 11) with reduced self-cleaning capability is embodied such that it permits an optical comparison with a fully self-cleaning subarea and

   - the at least one subarea (11) with reduced self-cleaning capability is arranged on a reflector plate (12).
2. Oven (1) according to claim 1, characterised in that the self-cleaning inner surface (1) has a self-cleaning layer with a first pore volume (V1) and the at least one subarea (11) with reduced self-cleaning capability has a layer with reduced self-cleaning capability with a second, reduced pore volume (V2).
3. Oven (1) according to claim 2, characterised in that the subarea with reduced self-cleaning capability is a compressed subarea.
4. Oven (1) according to claim 2, characterised in that the subarea (11) with reduced self-cleaning capability has pores filled at least partially by means of a filling material.
5. Oven (1) according to claim 2, characterised in that the subarea (11) with reduced self-cleaning capability has a subarea with a reduced thickness.
6. Oven (1) according to claim 5, characterised in that the subarea (11) with reduced self-cleaning capability has been generated by means of a material removal.
7. Oven (1) according to one of the preceding claims, characterised in that the subarea (11) with reduced self-cleaning capability can be provided from a primary material with reduced self-cleaning capability by means of laser machining.
8. Oven (1) according to one of the preceding claims, characterised in that at least one subarea (11) with reduced self-cleaning capability has a form of at least one character string.
9. Oven (1) according to claim 8, characterised in that the at least one subarea (11) with reduced self-cleaning capability has a form of a user instruction.
10. Oven (1) according to one of the preceding claims, characterised in that at least one optical comparison surface (13) which is predetermined according to colour is provided on the oven chamber (2).

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