EP2828582B1 - Door having an unventilated cavity for a domestic heat treatment device - Google Patents

Description

The invention relates to a door for a household heat treatment device, in particular cooking chamber, at least comprising a laterally encircling frame, which is front covered by an at least partially opaque front cover and the inside is covered by an at least partially opaque inner cover, wherein the frame, the front cover and the Inner cover enclose an unvented cavity.

The unvented cavity may be hermetically sealed, in which case due to a thermal expansion and contraction of a fluid in the cavity, in particular gas, during operation of the heat treatment device high mechanical stresses on the door may occur, which can lead to their damage. Alternatively, the cavity may be evacuated, but a long-term stable maintenance of the vacuum is very complex and expensive. The non-ventilated cavity may have a simple vent for pressure equalization, through which, however, dust, vapor etc. can penetrate into the cavity.

WO 2008/028099 A2 discloses an energy efficient, thermochromic device that can be used to let sunlight into a building or structure when there is no sunlight or a high angle of sunshine, and substantially block sunlight when it is directly irradiated to the window. Such a device can also be used in an oven door according to this document.

DE 42 40 096 A1 discloses a pressure compensating device with filter action for a device or article for balancing pressure differences between two atmospheres having different and fluctuating pressures, the atmospheres in particular having different temperatures and being differently composed. In a broader sense, the composition relates not only to gaseous but also to liquid and solid constituents, the latter essentially in the form of droplets (for example aerosols) and liquid films or dust-like particles. By means of the pressure compensation device, a filter effect is achieved at the same time during pressure equalization such that impairments of the function of the device or the object can be avoided, the filter effect depending on the requirements down to the molecular filter range (molecular sieve) can go down.

EP 0 475 285 A2 discloses an oven with a thermal insulated baking muffle equipped with an insulating layer of an airgel.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art, and in particular to provide an improved door for a household heat treatment apparatus having at least one non-ventilated cavity.

This object is achieved according to the features of the independent claim 1. Preferred embodiments are in particular the dependent claims. The object is achieved by a door for a household heat treatment device, at least comprising a laterally encircling frame, which is covered at the front by means of an at least partially opaque front cover and the inside is covered by an at least partially opaque inner cover, wherein the frame, the front cover and the inner cover enclose an unvented cavity. An unvented cavity is understood in particular to mean a cavity which is not intended to be flowed through by an air stream for its cooling. The frame may be a one-piece frame or a multi-part frame. The frame may serve as a door profile.

Furthermore, the cavity is at least partially filled with translucent airgel, and the door has at least one semipermeable pressure compensation element for pressure equalization between the cavity and an environment.

The translucent airgel ensures a sufficient view through the door and thus insight into a heat treatment space to be closed by the door. Airgel is also highly thermally insulating (thermal conductivity of only between 0.014 and 0.05 W / (m · K)), so that a heat flow from the heat treatment room in the outdoor area can be significantly reduced and the door is therefore very good heat insulation auszustbar. Another advantage of the airgel is that Melting point is so high (with silica airgel, for example, at about 1200 ° C), that it at temperatures, as they occur in household appliances (up to 500 ° C in a cooking chamber of a baking oven during a pyrolysis operation), neither melts nor worth mentioning elastically or plastically deformed. In addition, airgel is non-flammable and non-toxic.

In addition, airgel is transparent or practically transparent (quasi-transparent). Thus, in particular, an airgel thickness-dependent insight into a heat treatment space is made possible, for example for monitoring food to be cooked. Occurring in individual cases material haze by moisture is typically reversible up to a material-dependent limit by heating (energy input from the outside) of the airgel on its Desorptionsenthalpie. However, this is not mandatory and the airgel may only be translucent. This may be sufficient, for example, in household heat treatment appliances which do not require monitoring or evaluation of the object heat-treated in the heat treatment room, e.g. in so-called sterilizers.

In addition to absorbing moisture, airgel can also trap fine dust particles or oil droplets, etc. To prevent dust, vapors (including oils) or, to a greater extent, water from entering the cavity and affecting a function of the airgel, the (functional) semipermeable pressure compensation element at least holds solids (dust) and liquid (oil droplets, water droplets, etc.). back, but lets air through. This allows pressure equalization to take place, but prevents penetration of significantly detrimental liquids. Overall, this provides a mechanically less loaded, inexpensive door which can be cleaned with little effort. The airgel in particular provides a narrow and lightweight door. The "semipermeability" of the pressure compensation element is therefore generally functional in this sense and is not limited to the use of a semipermeable membrane or a semi-permeable filter.

The at least one semipermeable pressure compensation element is permeable to air and impermeable to liquids. By means of the air permeability, a pressure equalization is made possible by means of the impermeability to liquid (for substances in the liquid state, including droplets) prevents penetration of oil, water, etc.

The (functional) semipermeable pressure compensator has two oppositely-acting valves of which a first valve opens outwardly with respect to the cavity so that excess pressure from the cavity is vented through the first valve and a second valve opens inwardly with respect to the cavity that negative pressure in the cavity can be compensated by opening the second valve.

The second valve cooperates with a filter equipped with desiccant as filter material. It can e.g. be upstream of this flow or downstream. This filter is thus a general filter in the sense that it can retain certain substances when passing through a fluid, here in particular water.

The at least one semipermeable pressure compensation element is further vapor permeable. This allows the use of a comparatively simple and inexpensive pressure compensation element. While moisture from the environment may enter the cavity (e.g., as the door cools), this amount is relatively low due to the retention of droplets and may also be readily re-evaporated upon heating of the cavity.

The non-ventilated cavity may in particular be leak-tight, except for the at least one semipermeable pressure compensation element, which may cause unwanted intrusion of dust, liquid, etc. through gaps or the like. prevented.

In particular, the door may be a cooking chamber door, since cooking rooms can typically experience particularly high temperatures and their cooking appliance doors have thus hitherto been designed to be particularly expensive, e.g. equipped with a ventilation. The cooking appliance door may in particular be a baking-oven door, in particular a baking-oven door of a pyrolysis-capable baking oven.

The type of door is not limited and may e.g. include a door of a bakery, a hinged door or a revolving door.

It is an embodiment that the at least one semipermeable pressure compensation element has or is at least one membrane. This is very simple, inexpensive and with a low requirement for space can be used. The membrane is preferably exchangeable.

It is yet another embodiment that the at least one semipermeable pressure compensation element has at least one combination of the inwardly opening valve and the filter unit cooperating therewith. Through the valve, a volume of a compensating air flow is minimized, allowing a long-lasting filter capability of the filter unit. The filter unit is preferably exchangeable.

The valves can be arranged spatially close, in particular in a structural unit, or can be arranged spatially separated.

The valves may in particular be check valves.

The valves may be designed so that one or more valves are open or closed at normal pressure (without pressure difference).

It is also an embodiment that the at least one semipermeable pressure compensation element is arranged in a cold region of the cooking chamber door. This results in the advantage that the pressure compensation element is thermally loaded comparatively low. A cold region of the door may, in particular, be understood to mean a region which does not directly cover a charging opening of the heat treatment chamber and consequently is not exposed to direct heat radiation from the heat treatment chamber.

It is also an embodiment that the at least one semipermeable pressure compensation element is arranged in the frame. As a result, the pressure compensation element is positioned in a region in which it is opposite a flange in a closed position of the door and thus protected against external stress. In addition, the frame is relatively cold. The at least one semipermeable pressure compensation element may, in particular, be located in a left-side and / or right-side section of the frame.

It is still a further development that the at least one semipermeable pressure compensation element is on the underside portion of the frame. As a result, any condensate accumulating in the cavity can be dissipated particularly effectively. In addition, a water film can form more difficult on the pressure compensation element. Particularly preferred is a slightly inclined mounting.

It is a preferred embodiment for protection against external mechanical stress that the at least one semipermeable pressure compensation element is covered by a permeable protective cover, e.g. a grid or perforated screen.

It is also an embodiment that the front cover is a front glass panel and the inner cover is an inner glass panel. This allows a particularly large viewing surface. Alternatively, the front cover and / or the inner cover may have a frame in which a viewing window is inserted.

It is still an embodiment that the airgel is in the form of at least one airgel disc. In this case, "pane" is understood to mean a general transparent molded body or monolith, which in particular also has a mechanical appearance Be sensible plate-shaped or disc-shaped. The airgel disc can thus be designed in particular as a plate. The door then has at least one intermediate disc (between the windscreen and the inner pane) in the form of an airgel disc. As a result, a large-area insulation is made possible in a simple manner. A very steep temperature gradient can occur on the airgel disk during operation of a household heat treatment device, so that a surface temperature on the inside (facing the heat treatment chamber) of the airgel disk is high, which results in heat removal from the heat treatment space (eg by air cooling and / or or thermal radiation) low, but a surface temperature on the (the heat treatment space facing away) outside or front side is very low, so that here a high contact safety is possible. Thus, for example, a waiver of a door ventilation is also possible for very high temperatures, which in turn creates new space and thus allows more freedom of design. Furthermore, at least one conventional glass pane can be replaced by the at least one airgel pane, which results in considerable weight savings.

It is a further embodiment that in the cavity at least two superposed, individually produced airgel discs are housed, in particular plate-shaped discs. This embodiment has the advantage that it is relatively easy and inexpensive to produce, because thin airgel discs are much faster to produce than thick airgel discs. It is preferred that a single-piece airgel disc (or airgel plate) has a thickness between about 5 mm to 40 mm, preferably between about 10 mm and 20 mm, more preferably between about 12 mm and 16 mm ,

It is yet another embodiment that the at least one airgel disc is separated at least with respect to the inner pane by a gap. This gap further improves thermal insulation, since such direct heat conduction is prevented by contact between the inner pane and the adjacent airgel pane and heat transfer can only be generated by radiant heat and by gas movement or convection in the gap.

It is also an embodiment that the gap not more than 4 mm, in particular not more than 2 mm, in particular not more than about 1 mm, measures. It is an advantageous for avoiding unwanted contacting development that the gap is at least 0.1 mm wide.

It is still a development that the at least one airgel disc is also separated from the front screen by a gap, in particular to avoid contact with the windscreen.

Also, a plurality of spaced-apart airgel disks may be housed in the cavity.

It is also an embodiment that the at least one airgel disc is made of silica airgel.

The object is also achieved by a household heat treatment device having at least one heat treatment space that can be closed by a door, wherein the door is a door as described above. This gives the same benefits to the door, and the household heat treatment device can be designed analogously.

Thus, the household heat treatment device may preferably be a cooking appliance, in particular having an oven, in particular with a pyrolysis capability.

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 a door for a household heat treatment device in the form of a oven door 11 for an oven 12. In this case, the oven door 11 is shown in a view obliquely from the front with a left-sided portion 14 of a frame 13 shown offset. The oven door 11 closes in the illustrated upright position indicated by dashed lines heat treatment space in the form of a furnace chamber O. The oven door 11 is pivotable in a horizontal opening position (and back) and has to Hinge 21 on. The oven space O and the oven door 11 represent parts of the oven 12.

The frame 13 is laterally configured circumferentially and front side (the furnace chamber O facing away) covered by a front cover in the form of a front glass pane 15. On the inside (facing the furnace chamber O), the frame is covered by means of an inner cover in the form of an inner glass pane 16. The frame 13, the front glass pane 15 and the inner glass pane 16 enclose an unvented cavity 17 tightly. Within the cavity 17 are two superimposed, plate-shaped airgel discs 18, 19 of a respective thickness between about 12 mm and 16 mm. The inner airgel disc 18 is separated from the inner glass panel 16 by a gap d of more than 0.1 mm, but not more than 1 mm. The outer airgel disc 19 is opposite the front glass pane 15 is separated by a gap. Since the airgel discs 18, 19 are translucent and translucent, a large field of view through the oven door 11 in the oven space O is possible.

In order to allow a pressure equalization of the cavity 17 with an environment U of the oven door 11, the oven door 11 has a corresponding semipermeable pressure compensation element 20. The pressure compensation element 20 is arranged here in a lower region of the left-side portion 14 of the frame 13 and thus in a cold region of the oven door 11. The pressure compensation element 20 comprises at least one membrane. The pressure compensation element 20 is permeable to air and permeable to vapor, but liquid impermeable. For protection against mechanical damage, the pressure compensation element 20 is surrounded by a permeable protective cover 22, e.g. a grid, covered.

During operation of the oven 12, the oven space O is heated, which in turn heats the cavity 17. The expanding in the cavity 17 in a heating gas and possibly vapor present moisture can escape from the pressure compensation element 20, so that a pressure-induced mechanical load on the oven door 11 can be prevented.

By means of the airgel discs 18, 19, a stronger heating of the front glass pane 15 and the non-ventilated oven door 11 can be prevented because the airgel discs 18, 19 are highly thermally insulating. Due to a heating of the airgel disks 18, 19, if necessary, moisture held in them can be removed.

In a subsequent cooling of the furnace chamber O and thus also of the cavity 17 air flows from the environment U through the pressure compensation element 20 in the cavity 17. However, while dust and liquids (oil droplets, water droplets, etc.) are held.

In general, for example, the front cover and / or the inner cover may at least partially be integrated with the frame.

LIST OF REFERENCE NUMBERS

11

oven door

12

oven

13

frame

14

left-sided section

15

Front glass

16

Interior glass pane

17

unventilated cavity

18

plate-shaped airgel disc

19

plate-shaped airgel disc

20

Pressure compensation element

21

hinge

22

protective cover

O

furnace

U

Surroundings

Claims (10)

1. Door (11) for a domestic heat treatment device (12), in particular cooking compartment door, at least having a laterally circumferential frame (13), which is covered at the front by means of a front cover (15) which is transparent at least in areas and is covered in the inside by means of an inner cover (16) which is transparent at least in areas, wherein the frame (13), the front cover (15) and the inner cover (16) enclose an unventilated cavity (17), wherein

   - the door (11) has at least one semipermeable pressure equalisation element (20) for pressure equalisation between the cavity (17) and an environment (U), which is permeable to air and impermeable to fluid,

   - the at least one semipermeable pressure equalisation element (20) has an inwardly opening valve and opposite thereto an outwardly opening valve,

   - the inwardly opening valve interacts with a filter unit, which has drying means as filter material,
   characterised in that

   - the cavity (17) is filled at least partially with aerogel (18, 19) which is permeable to light and

   - the at least one semipermeable pressure equalisation element (20) is permeable to steam.
2. Door (11) according to claim 1, characterised in that the at least one semipermeable pressure equalisation element is arranged in a cold region (13, 14) of the door (11).
3. Door (11) according to one of the preceding claims, characterised in that the at least one semipermeable pressure equalisation element is arranged in the frame (13).
4. Door (11) according to claim 3, characterised in that the at least one semipermeable pressure equalisation element is disposed on a bottom section of the frame.
5. Door (11) according to claim 4, characterised in that the at least one semipermeable pressure equalisation element is mounted so as to be slightly inclined.
6. Door (11) according to one of the preceding claims, characterised in that the at least one semipermeable pressure equalisation element (20) is covered by a permeable protective cover (22).
7. Door (11) according to one of the preceding claims, characterised in that the front cover is a front glass panel (15) and the inner cover is an inner glass panel (16).
8. Door (11) according to one of the preceding claims, characterised in that the aerogel is present in the form of at least one aerogel panel (18, 19).
9. Door (11) according to one of the preceding claims, characterised in that the at least one semipermeable pressure equalisation element (20) has at least one combination comprising the inwardly opening valve and the filter unit interacting therewith.
10. Domestic heat treatment device (12), in particular cooking device, having at least one heat treatment compartment (O) which can be closed by a door, characterized in that the door is a door (11) according to one of the preceding claims.

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