EP2251588B1 - Lamp for household device and household device, in particular for preparing food, with a lamp - Google Patents

Description

The invention relates to a lamp for a household appliance, which has at least one light source and a translucent cover on the front side, which is connected to a housing part. Furthermore, the invention relates to a household appliance with a lamp.

In household appliances, such as ovens or the like, it is known that lamps are used to illuminate the cooking space. Since it usually gets very warm in the cooking chamber when the domestic appliance is in operation, the lamp is exposed to these conditions. Precisely when they are arranged in the cooking chamber or at least partially extend into the cooking chamber, specific lamp types can be impaired or damaged as a result. This temperature effect is relatively unproblematic with conventional oven lamps that have an incandescent lamp. However, these require a relatively large amount of energy during operation. Such a lamp disclose the EP 0 454 969 A2 , which discloses a lighting device for a stove, the GB 216,423 which discloses an improvement in lighting of a bakery oven and which DE 86 09 316 U1 , which reveals an oven.

Furthermore, the EP 446 692 A1 a lighting device with light guides, in particular for cold rooms and explosion-proof rooms and the WO 2008/047335 A1 Improvements to display case lighting.

It is the object of the present invention to create a lamp for a household appliance which is unproblematic with regard to the effect of heat and which can also be operated more energy-efficiently.

This object is achieved by a lamp having the features of claim 1 and a domestic appliance having the features of claim 12.

A lamp according to the invention for a domestic appliance comprises at least one light source. In addition, the lamp includes a front translucent cover. This Cover is connected to a housing part of the lamp. The light source is arranged on the side of the housing part facing away from the cover outside of the housing part. The housing part is tapered to the side. At least one transparent cover element is arranged in the beam path of the light source between the cover and the light source, light from the light source being able to be emitted from the lamp through the cover element and the cover. With such a configuration of the lamp with the cover and the cover element, the light source arranged behind it can be better protected from temperature influences. Furthermore, the lamp is designed for more energy-efficient operation.

A cover element is preferably arranged on the upper side of the housing part facing the light source. The cover element thus serves as a kind of cover of the housing part, so that the cover and the cover element are arranged on the opposite sides of the housing part. On the one hand, the configuration enables the cover element to be fastened as well as possible. On the other hand, this arrangement, so to speak, one behind the other and the positioning between the cover element and the cover arranged in a row with respect to the view in the longitudinal axis of the lamp allows the light from the light source to be emitted particularly easily and without complicated detours and distractions through these two components is.

The housing part has ventilation openings through which heat can be dissipated from a cavity formed by the housing part and the cover. A hollow chamber is formed by the housing part, the cover and a cover element arranged in particular on the housing part, so that when temperature is applied via the side of the cover, the heat can initially be kept in this cavity for the most part and not in large quantities via the cover element, even up to to the light source. This quasi-first heat accumulation space then enables this heat to escape through the ventilation openings in the housing part and overheating does not occur in this cavity. In particular, the ventilation openings are designed in such a way that the escaping heat is not conducted to the light source. In particular, it is provided that the ventilation openings are formed in an outer wall of the housing part that is positioned obliquely downwards relative to the horizontal. The heat can thus from the Cavity rise to the top and automatically escape from the cavity through the vents. The arrangement of the components cover, cover element and housing part on the one hand and the ventilation openings in the housing part on the other hand provide a particularly advantageous concept for the thermal decoupling of the light source from temperature loading of the lamp acting on the side of the cover.

The lamp preferably has a light shaft which is arranged on the side of the housing part which is remote from the cover, the light from the light source being able to be guided through the light shaft to the cover element. The light shaft is preferably arranged coaxially with the axis of the lamp. Through the light well, a spacer element is created between the arrangement comprising the housing part and the cover and in particular the cover element on the one hand and the light source on the other hand. The light source can thus be positioned further away from components of the lamp that are subject to temperature. At the same time, however, a particularly advantageous transmission of light to the cover can be ensured.

The light shaft is preferably fastened directly to the upper side of the housing part and connected to it. As a result, on the one hand, a mechanically stable arrangement can be created and, on the other hand, the lowest possible light losses can be achieved.

The cavity in the light well is preferably separated, in particular thermally decoupled, from the cavity between the housing part and the cover by the cover element.

Preferably, the light well is formed in a straight line and is in particular attached to a housing part. This configuration also means that the light shaft is arranged directly in front of the housing part in the viewing direction along the longitudinal axis of the lamp, viewed from the light source, so that no necessary light deflection elements or the like are required here either. The components mentioned are therefore arranged in particular in the main emission direction of the light source, which corresponds in particular to the longitudinal axis of the lamp or, if there are several light sources, at least one light source has a main emission direction parallel to this longitudinal axis of the lamp.

Preferably, the at least one light source is arranged on the end of the light well that faces away from the housing part, in particular outside of the light well. On the one hand, this allows for easy access to the light source and guarantees it there is also an additional cooling option for the light source with cooling air.

A carrier element, which carries the at least one light source, is preferably arranged on the end of the light shaft facing away from the housing part. The mechanically stable attachment can thereby be guaranteed.

The at least one light source is preferably arranged on a circuit carrier which is held by the carrier element. In particular, it is provided that the at least one light source is arranged on a heat sink which is connected to the carrier element. On the one hand, this heat sink enables particularly efficient heat dissipation from the light source and in particular the circuit carrier, and on the other hand the mechanically stable connection of the carrier element to this heat sink can be particularly suitable for holding the components.

The carrier element preferably has openings through which cooling air can flow for cooling the at least one light source. In particular, the carrier element is U-shaped in cross section. It can also be designed in such a way that at its corner points it only has upright columns with which the heat sink is held. As a result, the flow of cooling air can be further improved.

A further translucent cover element and/or an optical element for deflecting the light beam and/or an optical element for bundling or widening the light beam is preferably arranged in the light well. In addition or instead of this, it can be provided that the inside of the light shaft is designed with a light-reflecting layer, at least in some areas. As a result, the light losses can on the one hand be further reduced and the use of a further cover element and/or an optical element can ensure that the light is concentrated or widened for the best possible light emission and uniform illumination of a room. Mirrors or lenses etc. can be provided as optical elements.

It proves to be particularly preferred if at least one light source is a light-emitting diode and thus a light-emitting semiconductor component. This can be particularly compact and small and also enables particularly energy-efficient operation. With light sources of this type in particular, the design of the lamp enables problem-free use under relatively high temperature ambient conditions, as is the case, for example, in ovens or the like. Since light-emitting diodes are usually very temperature-sensitive, the lamp and its components can ensure that the light source is exposed to relatively low temperature loads even when the household appliance is in operation and the lamp can nevertheless be arranged at least in certain areas within the temperature-loaded room.

Furthermore, the invention relates to a household appliance, in particular for preparing food, which has a lamp according to the invention or an advantageous embodiment thereof. The domestic appliance can be designed, for example, as an oven with a cooking space.

In particular, it is provided that this domestic appliance has a receiving space, in particular a cooking space, to which heat can be applied by a heating device, the lamp being arranged to illuminate the receiving space and the cover of the lamp extending at least partially into the receiving space. The best possible illumination of the recording space can be guaranteed on the one hand, and particularly energy-efficient operation can be guaranteed on the other hand, particularly when light-emitting diodes are used as light sources, with precisely these light sources then being positioned outside of the recording space and excessive heat being applied to the light source can be avoided.

The lamp is preferably arranged in the ceiling of the accommodation space. In particular, this is installed in the ceiling in a gas-tight and moisture-tight manner. In particular, it is provided that the housing part is arranged in a sealing manner with respect to the ceiling of the receiving space.

Provision can be made for the housing part and the light shaft to be designed in one piece. A design made of plastic can be provided. However, the housing part and the light shaft can also be detachably connected in a non-destructive manner be, in this regard, a screw connection or a plug connection or a snap-in connection can be provided. Correspondingly, the light shaft and the carrier element can be designed in one piece. A realization made of plastic can also be provided here. However, it can also be implemented here that the light well and the carrier part are designed to be detachable without being destroyed, with reference being made to those of how they can be implemented between the housing part and the light well with regard to specific examples.

Preferably, the cover is detachably connected to the housing part in a non-destructive manner, it also being possible for a screw connection or a plug-in connection or a snap-in connection to be provided here in particular.

The at least one cover element, which is preferably arranged on the upper side within the housing part on the housing part, is also preferably arranged on the housing part so that it can be detached in a non-destructive manner. A plug-in connection can also be provided here as an advantageous embodiment.

The at least one arrangement of the cover element enables a thermal separation between the cavity in the arrangement formed between the cover and the housing part and the cavity in the light well to be achieved.

Up to the light source, no further supply of heat is thus achieved, so that the thermal irradiation of the light source can be minimized.

The cover element can be made of a glass material and can be clear, opaque or embodied as a diffuser lens. This cover element can also be glued into the housing part in addition to a simple insertion in the form of an insertion or clamping. The light well can also be designed in multiple stages, with several cover elements being arranged in this connection. A further improved thermal decoupling of the light source can then be achieved by these several cover elements, since additional cavities are formed, through which heat buffering can be achieved.

Provision is preferably made for an optical element to be arranged at the entrance of the light channel, it being possible for the optical element to be a converging lens, for example. As a result, the light from the at least one light source can be bundled and thus radiated up to the cover and out of the cover with the lowest possible losses. It can also be provided that instead of a lens for all light sources, each light source has an associated lens. This can be provided, for example, in an embodiment of the lamp with a plurality of light-emitting diodes. The bundled light can then be scattered again through the last cover element furthest away from the light source or through the cover in order to be able to achieve the most uniform possible illumination of the room to be illuminated with the lamp. Preferably, this cover element and/or the cover is designed as a milky, cloudy disk or as a diffuser lens.

On the circuit carrier, on which the light source, in particular the LEDs, is preferably arranged, a temperature sensor can also be arranged, which switches off the light-emitting diodes or regulates them down if the temperature is too high, in order to protect them from damage. The circuit carrier, which can be made of known materials or ceramics, is preferably glued to the heat sink, which is preferably made of aluminum, with a heat-conducting adhesive. The circuit carrier and the heat sink can also be designed in one piece from ceramic. The heat sink can be thermally coupled to an outer housing of the domestic appliance in order to increase the cooling surface.

The cover element or elements are preferably made of a material that is not thermally conductive or has poor thermal conductivity. For example, glass can be provided.

It is precisely when one or more light-emitting diodes are used as the light source or light sources that a significantly more energy-efficient operation can be made possible compared to a lamp with a conventional glow-wire illuminant. Due to the smaller size of the light-emitting diodes, the opening in the ceiling of the recording room can then also be made smaller than in the case of conventional glow-wire lamps. This reduces heat loss through the smaller, non-insulated spot. This leads to lower energy consumption of the entire device when preparing food. By the use of LEDs, the color temperature of the light can also be chosen almost freely. This also enables lighting that appears more similar to normal daylight to the observer than is the case with conventional light sources.

Further features of the invention result from the claims, the figures and the description of the figures.

Fig. 1

eine schematische perspektivische Darstellung eines erfindungsgemäßen Hausgeräts;

Fig. 2

eine schematische Schnittdarstellung der Lampe im Hausgerät gemäß Fig. 1;

Fig. 3

eine Seitenansicht eines Ausführungsbeispiels einer erfindungsgemäßen Lampe; und

Fig. 4

eine perspektivische Schnittdarstellung der Lampe gemäß Fig. 3.

An embodiment of the invention is explained in more detail below with reference to schematic drawings. Show it:

1

a schematic perspective view of a household appliance according to the invention;

2

according to a schematic sectional view of the lamp in the household appliance 1 ;

3

a side view of an embodiment of a lamp according to the invention; and

4

a perspective sectional view of the lamp according to FIG 3 .

Elements that are the same or have the same function are provided with the same reference symbols in the figures.

In 1 is a perspective view of a domestic appliance for preparing food, which is designed as a baking oven 1. The oven 1 comprises a receiving space designed as a cooking chamber 2 into which foodstuffs can be placed for preparation. The cooking chamber 2 is delimited by a muffle 3 or its walls, with a front opening being formed through a door 4 can be closed. At least one lamp 6 is formed in a cover 5 of the muffle 3 . Both the number and the position of the lamp 6 are merely exemplary.

The cooking chamber 2 is illuminated with the lamp 6 when the oven 1 is in operation. Not shown devices for generating heat, such as radiators, generate heat in the cooking chamber 2, through which the food can be cooked. This heat also acts on the lamp 6, with the design of the lamp 6 making it possible to prevent the light source of the lamp 6 from being subjected to heat in an undesirable manner.

In 2 1 is a schematic representation of a sectional view of an exemplary embodiment of the lamp 6 according to its arrangement in the ceiling 5. The lamp 6 extends into the cooking chamber 2 in certain areas. An insulating material 7 is attached to the ceiling 5 outside of the cooking chamber 2 . In the insulating material 7 and the ceiling 5 there is an opening 8 through which the lamp 6 extends and is formed on both sides of the ceiling 5 .

The lamp 6 comprises a light-transmitting cover 9 on the front side, which is made of glass, for example. The cover 9 extends into the cooking chamber 2. The lamp 6 also includes a housing part 10, which is formed in one piece from plastic, for example. The cover 9 is screwed into the housing part 10 . The housing part 10 is connected to the cover 5 in such a way that the opening 8 is sealed gas-tight and also moisture-tight. A separate sealing element can be provided for this purpose.

The cover 9 is screwed to the housing part 10 at a lower end 12 thereof, a screw connection 11 being provided for this purpose in the exemplary embodiment. The cover 9 can thus be detached from the housing part 10 without being destroyed.

A cavity 13 is formed by the housing part 10 and the cover 9 .

The housing part 10 has at its upper end 14 and thus at the end 14 facing away from the cover 9 an opening which is covered by a first transparent cover element 16 . The cover element 16 is on the inside of the Housing part 10 attached, for example, a pinch or an insertion or a gluing can be provided. The cover 9 and the cover element 16 are arranged on opposite sides 12 and 14 of the housing part 10, but arranged in series with one another in the direction of the longitudinal axis of the lamp, which in the exemplary embodiment is the same as the main emission direction H of at least one centrally positioned light source 23. The opening 15 is covered by the cover element 16 so that the cavity 13 is closed via the opening 15 . The cover element 16 is made of a translucent material, in particular glass, so that in addition to transparency, thermal decoupling of the light source 23 can also be achieved, with the cover element 16 being coated accordingly or having a corresponding material component.

The housing part 10 tapers towards the upper end 14, ventilation openings 17 and 18 being formed on this taper and on the oblique outer wall produced thereby. The number of ventilation openings 17 and 18 is only an example; several ventilation openings of this type can also be provided, which are not identified in any more detail.

The heat W generated in the cavity 13 during operation of the baking oven 1 can be dissipated via these ventilation openings 17 and 18 in accordance with the arrow illustration. Directly adjoining the upper end 14 is a light shaft 19 which, on the one hand, contributes to guiding the light L of the light source 23 and to further creating a distance between the light source 23 and the cooking chamber 2 . The light shaft 19 has an inner side 20 which is made of a highly light-reflecting material, at least in some areas. In addition, the light well 19 is coaxial with the longitudinal axis of the lamp 6 . The light shaft 19 is designed in a straight line, so that the light L of the light source 23 can be emitted in the main emission direction and does not have to be deflected. In the exemplary embodiment, a further translucent cover element 22 is arranged on an upper end 21 of the light shaft 19 facing away from the housing part 10 . This can also be designed as an optical element in the form of a converging lens. In addition, it can be provided that at least one further cover element and/or one optical element is arranged in the light shaft 19, so that several are also separated in the light shaft 19 Cavities are formed in a cascade. In the embodiment shown, only the entire cavity 28 is shown. The thermal decoupling of the at least one light source 23 can be further improved by this configuration of cavities 13 and 28 one behind the other.

The light source 23 is in the form of a light-emitting diode, which is arranged on a circuit carrier 24 . The light source 23 is formed outside of the light well 19 and positioned adjacent to the top 21 of the light well 19 .

The light source 23 and the circuit carrier 24 are attached to a heat sink 25 in the exemplary embodiment. This cooling body 25 also enables the heat of the light source 23 to be dissipated and is preferably thermally coupled to a housing (not shown) of the oven 1 so that an enlarged design of the cooling body can be produced for heat dissipation.

In addition, the lamp 6 includes a carrier element 26, which in 2 is not recognizable. The carrier element 26 is connected to the light shaft 19 and the heat sink 25 and carries the heat sink 25 and thus also the circuit carrier 24 and the at least one light source 23.

The carrier element 26 is designed in one piece and comprises openings through which cooling air K can flow in laterally and out again on the other side, so that the light source 23 can be cooled by the cooling air flow K.

In the exemplary embodiment shown, the components of the lamp 6 are positioned in series with one another in the main emission direction H of the centrally positioned light source 23 and thus also the longitudinal axis of the lamp 6, with first the light source 23, then the light well 19, then the first cover element 16, the housing part 10 and the cover 9 follow.

Temperatures of, for example, 275° C. occur in the cooking chamber 2, as a result of which the lamp 6 is also thermally loaded. Heat is therefore generated in the cavity 13, this heat W being dissipated via the ventilation openings 17, 18 in such a way that the lamp 23 is not impaired.

In the exemplary embodiment, the light L from the light source 23 is essentially radiated in the main emission direction H through the light well 19 and the cover element 16 and the cover 9 into the cooking chamber 2 . Outside the cooking chamber 2 in the area of the light source 23, maximum temperatures of up to approximately 70° C. occur.

A plurality of light sources 23 in the form of a plurality of light-emitting diodes is preferably used.

In 3 a side view of the lamp 6 is shown. In this configuration, the components can be seen from the outside, with the connection between the light shaft 19 and the heat sink 25 by means of the carrier element 26 being particularly visible. The carrier element 26 has relatively large openings 27a, through which cooling air K can flow through the carrier element 26 in the direction of flow perpendicular to the figure sheet and can thus cool the plurality of light sources 23a, 23b and 23c. In addition, provision can also be made for additional openings 27b to be formed in the carrier element 26, as a result of which a cooling air flow in the plane of the figure can cool the light sources 23a to 23c from the other side, as it were.

In 4 12 is a sectional perspective view of the lamp 6 as shown in FIG 3 shown, with the cutting plane in 3 lies in the plane of the figure and the representation in 4 shows a representation rotated somewhat about the lamp axis. Here, too, the structure of the carrier element 26 can be seen, which has columns that project upwards at the corners, through which the connection to the heat sink 25 is provided. In addition, the underside of the cooling body rests on the carrier webs of the carrier element 26 . The circuit carrier 24 is fastened to this underside of the heat sink 25, and in this regard bonding with a thermally conductive adhesive is provided.

Reference List

1

oven

2

cooking chamber

3

muffle

4

door

5

cover of the muffle

6

lamp

7

insulation material

8th

opening

9

cover

10

housing part

11

screw connection

12

lower end

13

cavity

14

top end

15

opening

16

cover element

17, 18

vents

19

light well

20

inside of the light well

21

top end

22

cover element

23, 23a, b, c

light source(s)

24

circuit carrier

25

heatsink

26

carrier element

27a, b

openings

H

beam path

L

Light

W

warmth

Claims (13)

1. Lamp (6) for a household appliance (1), which has at least one light source (23), a housing part (10) and a front-side trough-shaped cover (9) that is permeable to light, which is connected to the housing part (10), wherein the at least one light source (23; 23a, 23b, 23c) is arranged on the side (14) of the housing part (10) that is remote from the cover (9), and wherein at least one cover element (16, 22) that is formed from a material that is permeable to light is arranged in the beam path (H) of the at least one light source (23), wherein light (L) of the at least one light source (23; 23a, 23b, 23c) can be emitted from the lamp (6) through the at least one cover element (16, 22) and the cover (9), wherein a first cover element (16) is arranged on the side (14) of the housing part (10) that is facing the at least one light source (23; 23a, 23b, 23c) in order to cover an opening (15) of the housing part (10) on the side (14) of the housing part (10) that is remote from the cover (9), wherein the housing part (10) is designed as tapered towards the side (14), the at least one light source (23; 23a, 23b, 23c) is arranged outside of the housing part (10) and the first cover element (16) is designed in addition to the permeability to light to also achieve a thermal decoupling of the light source and the first cover element (16) is accordingly coated or has a corresponding material component for this purpose, wherein the housing part (10) has ventilation openings (17, 18) through which heat (W) can be dissipated from a hollow space (13) that is formed by the housing part (10) and the cover (9).
2. Lamp (6) according to claim 1, characterised in that a light shaft (19) is arranged on the side (14) of the housing part (10) that is remote from the cover (9) and the light (L) of the at least one light source (23; 23a, 23b, 23c) can be guided through the light shaft to the cover element (16, 22).
3. Lamp (6) according to claim 1 and 2, characterised in that the hollow space (28) in the light shaft (19) is separated by the cover element (16, 22) from the hollow space (13) between the housing part (10) and the cover (9).
4. Lamp (6) according to claim 2 or 3, characterised in that the light shaft (19) is designed as straight and is fastened to the housing part (10).
5. Lamp (6) according to one of claims 2 to 4, characterised in that the at least one light source (23; 23a, 23b, 23c) is arranged on the end (21) of the light shaft (19) that is remote from the housing part (10).
6. Lamp (6) according to one of claims 2 to 5, characterised in that a carrier element (26) is arranged on the end (21) of the light shaft (19) that is remote from the housing part (10) and the carrier element supports the at least one light source (23; 23a, 23b, 23c).
7. Lamp (6) according to claim 6, characterised in that the at least one light source (23; 23a, 23b, 23c) is arranged on a circuit carrier (24) that is held by the carrier element (26).
8. Lamp (6) according to claim 6 or 7, characterised in that the at least one light source (23; 23a, 23b, 23c) is arranged on a cooling body (25) that is connected to the carrier element (26).
9. Lamp (6) according to one of claims 6 to 8, characterised in that the carrier element (26) has openings (27a, 27b) through which cooling air (K) can flow so as to cool the at least one light source (23; 23a, 23b, 23c).
10. Lamp (6) according to one of claims 2 to 9, characterised in that a further cover element (22) that is permeable to light and/or an optical element for deflecting the light beam and/or for bundling or separating a light beam is arranged in the light shaft (19) and/or a light-reflecting coating is formed on the inner side (20) of the light shaft (19).
11. Lamp (6) according to one of the preceding claims, characterised in that the at least one light source (23; 23a, 23b, 23c) is a light-emitting semiconductor component.
12. Household appliance (1) having a lamp (6) according to one of the preceding claims.
13. Household appliance (1) according to claim 12, which has a receiving compartment (2) that can be influenced with heat by a heating facility, wherein the lamp (6) is arranged so as to illuminate the receiving compartment (2) and the cover (9) extends at least in regions into the receiving compartment (2).

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