WO2013083474A1

WO2013083474A1 - Door for a domestic thermal-treatment device

Info

Publication number: WO2013083474A1
Application number: PCT/EP2012/073964
Authority: WO
Inventors: Jochen Herbolsheimer; Robert KÜHN
Original assignee: BSH Bosch und Siemens Hausgeräte GmbH
Priority date: 2011-12-09
Filing date: 2012-11-29
Publication date: 2013-06-13
Also published as: EP2788687A1; DE102011088093A1

Abstract

The invention relates to a door (1) provided for a domestic thermal-treatment device (B), said door (1) comprising a viewing window (2) and this viewing window (2) having at least one aerogel disc (5, 5a, 5b) that consists of a light-permeable aerogel. A domestic thermal-treatment device (B) comprises such a door (1), and this device can, in particular, be an oven (B) capable of pyrolysis.

Description

Door for a household heat treatment device

The invention relates to a door for a household heat treatment apparatus, wherein the door has a viewing window. The invention further relates to a household heat treatment device with a door equipped with a viewing window.

For example, for ovens oven doors are known which have a viewing window. The viewing window may have a disc package, which has an adjacent to a heat treatment chamber inner pane, an outer side outer pane and a between see the inner pane and the outer pane disposed intermediate disc. Such a disk package substantially reduces a temperature at the outer disk compared to a single disk or to a disk package with only one inner disk and one outer disk. However, the temperature on the outer pane during prolonged operation of the oven, especially in a pyrolysis operation, rise to an undesirably high value. To reduce this temperature even further, ventilated oven doors are known which can produce a cooling air flow in the disk pack. The ventilation may be passive by heat convection and e.g. a use of the Venturi effect can be performed or active by means of a fan. Thus, it takes a lot of effort to keep a temperature at the outer pane at a low level. By means of the aeration heat dissipation may also be increased from a cooking chamber closed by the oven door, so that an energy balance is deteriorated.

WO 2010/080060 A1 discloses an energy-saving window which has a transparent sheathing which encloses a transparent plate of silica airgel. After evacuation, a thermal conductivity at room temperature of a few mW / (mK) is achieved. This energy-saving window is intended for buildings and consequently for room temperature applications. 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 possibility for thermal insulation of a viewing window of a door for a household heat treatment device. This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims. The object is achieved by a door for a household heat treatment device, wherein the door has a viewing window and wherein the viewing window has at least one airgel disc (or plate) made of a translucent airgel. The door is typically provided to close a heat treatment room of the household heat treatment apparatus, the viewing window allowing a view into the heat treatment room. The heat treatment room is heatable for the treatment of objects housed in it.

Due to the at least one airgel disc, which in each case has a very low thermal conductivity of only between 0.014 and 0.05 W / (m-K), a heat flow from the heat treatment space to the outside area can be considerably reduced. In the operation of the household heat treatment device, a very steep temperature gradient may occur at the airgel disk, 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 heat treatment) / or thermal radiation) low, but a surface temperature on the (the heat treatment space facing away) outside is very low, so that a high contact safety is possible here. For example, a waiver of door ventilation is made possible, which in turn creates new space and thus allows more design freedom. The door can thus be an unventilated door in a development, even for pyrolysis. Furthermore, at least one conventional glass pane can be replaced by the at least one airgel pane, which results in considerable weight savings.

A further advantage of the airgel disc is that its melting point is so high (in the case of silica airgel, for example, at about 1200 ° C) that it occurs at temperatures that occur in household appliances (up to 500 ° C in a cooking chamber an oven during a pyrolysis operation), neither melt nor deform appreciably elastically or plastically. In addition, the airgel disc is non-flammable and non-toxic. It is an embodiment that the at least one airgel disc is transparent or practically transparent (quasi-transparent). As a result, in particular a crisp and true color insight into a heat treatment space (cooking chamber) of a Haushaltsgargeräts is possible, for example for monitoring of food. In some cases, translucent material haze caused by moisture is typically reversible by heating the airgel disc to a temperature above 100 ° C. However, this is not mandatory, and the airgel disc 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, for example so-called sterilizers.

It is still an embodiment that the viewing window has a disc package, which has an adjacent to a heat treatment chamber inner pane, an outside outer pane (windshield) and at least one spaced between the inner pane and the outer pane intermediate disc, and that at least one intermediate disc of at least one airgel Washer is constructed. As a result, the airgel disk can be protected by means of the outer disk and the inner disk, in particular against mechanical stress and contamination by liquid, dust, vapors, etc. Basically, all intermediate disks can be made of aerosol. Alternatively, at least one disc may be made of a different material than airgel, e.g. made of borosilicate.

It is a further embodiment that the disc package has an intermediate disc, which is constructed from at least two superimposed, individually produced airgel discs. Such a washer has the advantage that it is comparatively 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 , Such plates are relatively easy to produce and handle.

It is yet another embodiment that the intermediate disc is separated at least with respect to the inner pane by a gap. This gap improves a heat insulation further, since such a direct heat conduction is prevented by a contact between the inner pane and the washer and a heat transfer can only be generated by radiant heat and by a 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 further development that at least one intermediate disc is also separated from the outer disc by a gap, in particular in order to avoid contact with the outer disc. However, it is alternatively also possible for the at least one intermediate disk to substantially fill the entire gap between the inner disk and the outer disk. This causes a particularly high temperature drop across the washer.

Also, there may be a plurality of airgel spacers spaced apart from each other.

It is also an embodiment that the at least one washer is housed in a sealed interior of the heat appliance door. This prevents the at least one clouding in as an airgel washer in the course of an operation and thus loses its transparency, in particular transparency. The interior may for example be limited in part by the inner pane and by the outer pane. The interior may also be e.g. be limited by spacers for the inner pane and the outer pane and / or by lateral door profiles. It is also an embodiment that the at least one airgel disc is made of silica airgel.

In particular, the door may be a cooking appliance door, since cooking appliances may typically experience particularly high temperatures in the heat treatment space ("cooking space"). NEN and their cooking appliance doors are thus previously designed particularly complex, for example, are 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 include, for example, a door of a back car, a hinged door or a revolving door.

The object is also achieved by a household heat treatment device with a door as described above. The household heat treatment device may be, for example, a clothes dryer, a sterilizer or a cooking appliance. The cooking appliance may be, for example, a steamer or an oven. The oven may in particular be an oven (including a combination appliance, for example with a microwave function and / or a steam cooking function). The oven may in particular be a pyrolysefähiger oven.

In the following figures, the invention will be described schematically with reference to exemplary embodiments. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity. 1 shows a sectional view in an oblique view of an upper section of a door of a household heat treatment device; and

2 shows a sectional view in an oblique view of a sketch of the door.

1 shows a sectional view in an oblique view of an upper section of a non-ventilated oven door 1 for a household heat treatment device in the form of a baking oven B. Fig.2 shows a sketch of the oven door 1 in side view.

The oven door 1 has a viewing window 2 for viewing outside A in a serving as a heat treatment chamber oven space G of the oven B. The viewing window 2 is constructed as a transparent disc package which has an inner pane 3 adjoining the oven space G, an outer pane (front pane) 4 and an intermediate pane 5 spaced between the inner pane 3 and the outer pane 4. While the inner pane 3 and the outer pane 4 each consist of borofloat glass, the intermediate pane 5 is constructed of transparent silica airgel. And Although the intermediate disc 5 is composed of two airgel discs 5a, 5b of a width of approximately 12 mm to 16 mm, which lie flat against each other. By means of the airgel washer 5 constructed in this way, a very high thermal insulation is achieved which, first, keeps a heat flow from the furnace chamber G low and, secondly, a temperature at an outside surface of the outer pane 4, which can be touched by a user during operation of the oven B is, keeps low. This can also be achieved for high temperatures of up to 500 ° C. or even higher in the oven space G without passive or active ventilation of the oven door 1. The replacement of one or more conventional glass washers also results in a considerable weight saving of the oven door. 1

As can be seen in particular from FIG. 2, the airgel intermediate disk 5 is separated from the inner disk 3 by a first, thin gap d1 having a width of approximately 1 mm, and from the outer disk 4 by a second, wider gap d2 having a width of about 3 mm. The gaps d1 and d2 prevent contacting of the airgel intermediate disk 5 with the inner disk 3 or the outer disk 4, specifically to protect the airgel intermediate disk 5 against mechanical stress. In addition, a direct heat conduction is prevented by the gaps d1 and d2. This effect is more pronounced for the first gap d1. Consequently, in particular, the second gap d2 can also be drawn, so that the airgel intermediate disc 5 rests directly on the outer pane 4. Such a configuration is also highly thermally insulating for the second gap d2, since airgel has a lower thermal conductivity than air.

The inner pane 3, the outer pane 4, lateral door profiles (see above), an upper spacer 6 and a lower spacer 7 form an interior space 8 in which the airgel washer 5 is accommodated. The inner space 8 is sealed so as to prevent the airgel washer 5 from starting over time and losing its transparent property. Also, such contamination, e.g. by dust, vapors, etc. prevented. The interior 8 may be generally filled with air or a inert or inert gas, e.g. Nitrogen or a noble gas, to be filled. The interior 8 may alternatively be evacuated to allow even better thermal insulation.

Altogether, a heat flow W from the oven space G to the outside A through the viewing window 2 can at least roughly be composed as follows: At the boundary between the Furnace space G and the directly adjacent inside of the inner pane 3 is a heat transfer to the inner pane 3 by forced heat convection and heat radiation instead. The heat flows by means of a heat conduction through the inner pane 3, wherein in the inner pane 3, a negative heat gradient in the flow direction of the heat flow W to the outside A occurs. The inner pane 3 is therefore colder on its outer side than on its inner side. At the following first gap d1, the heat conduction is interrupted, and a heat flow through the first gap d1 can occur only by free convection (in the case of non-evacuated interior 8) and heat radiation. In the adjoining the gap d1, very low thermal conductivity airgel washer 5 occurs a very high negative heat gradient in the direction of flow to the outside A, so that an adjacent to the second gap d2 surface of the airgel washer 5 is already considerably colder than the furnace chamber G. The temperature decreases further in the following second gap d2 (heat transfer by free convection (in the case of non-evacuated interior 8) and heat radiation) and by the outer pane 4 (heat transfer by heat conduction). As a result of the low heat flow W, prolonged contact with the outside of the outer pane 4 leads to a rapid drop in temperature at the point of contact. On the outside of the outer pane 4, such a baking oven door 1 can still be touched with a reduced risk of burns if pyrolysis is carried out in the oven space G.

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

Thus, the household heat treatment device may also be another cooking appliance, or even a household appliance which is not a cooking appliance (for example a drying oven).

The door may generally have more than one washer, in particular more than one airgel washer. Moreover, an airgel washer may consist of only one airgel disk or more than two airgel disks lying flat on one another. LIST OF REFERENCES

1 oven door

2 viewing windows

3 inner pane

4 outer pane

5 washer

5a airgel disc

5b airgel disc

6 upper spacer

7 lower spacers

8 interior

A outside

B oven

G oven room

W heat flow d1 first gap d2 second gap

Claims

claims

1. door (1) for a household heat treatment device (B), wherein the door (1) has a viewing window (2), characterized in that the viewing window (2) at least one airgel disc (5, 5a, 5b) of a translucent airgel.

2. door (1) according to claim 1, characterized in that the at least one airgel disc (5, 5a, 5b) is transparent or quasi-transparent.

3. door (1) according to any one of the preceding claims, characterized in that the viewing window (2) has a disc package (3-5) having an adjacent to a heat treatment chamber (G) inner pane (3), an outer side outer pane (4) and at least one between the inner disc (3) and the outer disc (4) spaced apart washer (5) and that at least one intermediate disc (5) from at least one airgel disc (5a, 5b) is constructed.

4. door (1) according to claim 3, characterized in that the disc package (3-5) has an intermediate disc (5), which is composed of at least two superposed airgel discs (5a, 5b).

5. door (1) according to claim 4, characterized in that the intermediate disc (5) at least with respect to the inner pane (3) by a gap (d1) is separated.

6. door (1) according to claim 5, characterized in that the gap (d1) not more than 4 mm, in particular not more than 2 mm, in particular not more than about 1 mm, measures.

7. door (1) according to one of claims 4 to 6, characterized in that the at least one intermediate disc (5) in a sealed interior (8) of the door (1) is housed.

8. door (1) according to any one of the preceding claims, characterized in that the at least one airgel disc (5, 5a, 5b) consists of silica airgel.

9. door (1) according to any one of the preceding claims, characterized in that the door (1) is a cooking appliance door, in particular oven door.

10. Household heat treatment device (B) with a with a viewing window (2) equipped door (1), characterized in that the household heat treatment device is a Haushaltsgargerät, in particular a pyrolysefähiger oven (B), and the door (1) is a door (1) according to any one of the preceding claims.