EP2187703A1 - Cooking device with microwave feed - Google Patents

Abstract

The cooking appliance (1) has an interior that includes a cooking chamber (9) for receiving food to be cooked, and elements for generating microwaves, and for guiding the microwaves to a circularly or elliptically polarized antenna (14). A reflective microwave fan (36) is arranged to circulate the atmosphere in the interior and for the homogenization of microwave energy distribution in the interior rotation.

Description

The invention relates to a cooking appliance, comprising: an interior comprising a cooking chamber for receiving food to be cooked; and means for generating microwaves and guiding the microwaves to at least one circularly or elliptically polarized antenna arranged to radiate the microwaves along a direct path into the interior space.

From the US 4,596,915 is a cooking appliance with a microwave antenna and means for exciting the antenna for the purpose of emitting circularly polarized radiation known. The cooking appliance also comprises means for moving the antenna in the form of a turbine driven by an air flow with vertical blades, resulting in a large space requirement and a complex construction. The air flow is generated by a fan located in a space next to the cooking chamber. The microwave energy is coupled via a probe in the antenna, wherein the probe freely rotatable through an opening in a Garraumdecke protrudes into a waveguide. This opening is not hermetically sealed.

A generic cooking appliance is from the KR 10 0290708 B known. The known cooking appliance comprises a magnetron connected to a helix antenna. The helical antenna is arranged in a waveguide open to the cooking chamber and has a longitudinal axis which is directed into the cooking chamber. The waveguide is designed in the form of a blunt pyramid. The food to be heated is to be placed on a turntable. Thus, the cooking chamber design is not very flexible because, for example, no rack racks or racks can be used for food support.

The invention has for its object to overcome the disadvantages of the prior art, at least partially. In particular, a cooking appliance with a very good microwave energy distribution, which is flexible to use and inexpensive to manufacture, can be delivered without requiring a large amount of space.

This object is achieved in that in the interior of a separate from the antenna, at least partially reflecting microwave fan wheel for circulation of atmosphere in the interior and to even out the microwave energy distribution in the interior is rotatably arranged.

It is preferred that the interior is delimited by at least one wall and / or at least one wall part, and on an interior facing the front of one of the walls or the wall parts, the antenna is arranged, in particular at least one first wall via a wall part in a second Wall passes, extending extensions of the two walls on a side facing away from the interior rear side of the wall portion and the antenna is attached to an interior facing the front of the wall part.

It can also be provided that the fan is disposed on the first or the second wall, and / or at least one of the first and the second wall forms a rear wall or side wall of the interior, and / or represent the extensions of the two walls imaginary extensions.

With the invention it is further proposed that at least two antennas are arranged at different levels, preferably one below the other, in the cooking appliance, in particular one antenna, above the axis of rotation of the fan and the other antenna below the axis of rotation of the fan, and / or the fan as Radial fan is formed.

In addition, it may be provided that each antenna comprises a conductor with at least one turn, in particular a helical antenna, which extends around a longitudinal axis oriented or alignable in the direction of the interior.

Embodiments of the invention are preferably, characterized in that the interior is at least partially divided by a flow guide into a pressure chamber and the cooking chamber, the fan and each antenna are in the pressure chamber, and the flow control in a suction of the fan one, in particular centrally, opening has and at least one edge, at least one, in particular slit-shaped, air-permeable opening leaves free.

It can also be provided that the means for guiding the microwaves comprise at least one microwave guide structure located substantially outside the interior, with a section extending to at least one opening in the wall or the wall part, wherein in particular the section has a fixed, conductive outer wall having a round, in particular circular, cross-sectional shape and / or a coaxial waveguide with an inner conductor which is connectable or connected to a conductor of the arranged at the front of the wall or the wall part antenna comprises.

In this case, it is proposed that the inner conductor extends to a waveguide encompassed by the microwave guide structure, in which, in particular, at least one antenna extends at least one magnetron.

Finally, the invention proposes that at least one further device for the treatment of food to be cooked is provided, the further device in particular comprising an electric or gas-operated heater, a heat exchanger, a moisture removal device and / or a moisture supply device.

The invention is based on the surprising finding that with at least one circularly or elliptically polarized antenna in a cooking appliance, which is arranged such that it emits microwaves along a direct path into the interior of the cooking appliance, and arranged in the interior of the antennas separate, at least partially reflecting microwave fan impeller a very uniform microwave energy distribution in the interior for cooking on reproducible high quality can be realized. Circular or elliptically polarized radiation (hereinafter only circularly polarized radiation will be mentioned) is to be regarded as radiation with two orthogonal components which are independent of one another and therefore do not interfere. However, each individual component could still form standing waves, which would lead to different Garzonen in the interior, so a turbulence of the microwaves is forced by means of moving reflecting surfaces of the fan. The combination of circularly polarized microwaves with moving reflecting surfaces is very effective because the orthogonal components of the microwaves are reflected differently, and it is also structurally simpler, movable reflecting surfaces and a stationary Antenna use, since in the case of a moving antenna for an equally good dispersion would need an irregular wall surface. The application of the cooking appliance according to the invention is relatively large in two respects. On the one hand, the use of the fan wheel opens up the possibility of circulating the atmosphere. On the other hand, due to the swirling of the microwave energy in the cooking appliance, in which the interior and / or partial spaces of the interior space form resonator chambers, food can be arranged in various ways. The fan thus fulfills at least two functions, which saves costs and space. Furthermore, the use of the antenna which emits microwaves along a direct path into the interior, and arranged in the interior, at least partially microwave reflecting fan wheel also means that the cooking appliance can be made more compact, as is the case when in one in addition to the interior waveguide arranged a mode mixture is made.

If the interior is delimited by at least one wall and / or at least one wall part and the antenna is arranged on an interior of the front wall or the wall part, eliminating the need to guide the microwave waveguide through the interior. Rather, the means for generating microwaves from outside the interior of the antenna to the antenna may be made relatively short and with little lossy transients or angles.

If, in addition, at least one first wall merges with the second wall via the wall part, extensions of the two walls intersect at least imaginarily on a rear side of the wall part facing away from the interior, and the antenna is attached to a front side of the wall part facing the interior, then the cooking appliance is made possible even more compact. The wall part leads to a shortening of the two walls and is arranged obliquely to the same, so that outside the interior, namely in the space between the rear side of the wall portion and behind the wall portion intersecting, at least imaginary extensions of the two walls, the means for generating microwaves and at least partially disposable for guiding the microwaves. The first and second walls are walls that extend in at least two, preferably mutually perpendicular, directions over much of the corresponding dimension of the interior so as to substantially define the depth, width or height of the interior.

If the fan wheel is arranged on the first or the second wall, only an installation space is to be provided adjacent to the interior, in which drive means for the fan wheel and the means for generating microwaves and for guiding the microwaves to the antenna can be arranged. If the first or the second wall forms a rear wall or side wall of the interior, the installation space is not located in the bottom area or ceiling area of the cooking appliance. This reduces the overall height of the cooking appliance so that it can be stackable and simplifies the sealing of the wall openings required to connect the antennas to the microwave generating means and the fan to its drive means.

If at least two antennas are arranged at different levels in the cooking appliance, in particular at levels on opposite sides of the axis of rotation of the fan, it is easier to avoid that the microwave energy is concentrated predominantly in one half of the interior, for example because the fan wheel the interior in two Parts parts. This would otherwise be possible in particular if the fan is designed as a radial fan. On the other hand, the use of a radial fan is quite advantageous because its blades have a relatively large lateral reflecting surface, which reflect well the emitted from the side of the radial fan antennas microwaves. A radial fan is also more efficient in promoting the atmosphere.

If each antenna comprises a conductor with at least one winding, in particular a helical antenna, which extends around an aligned or alignable longitudinal axis in the direction of the interior, the microwaves are also radiated directly in the direction of the interior. With several turns more energy can be radiated. If the diameter of the turns is not quite equal, microwave energy is delivered with a certain bandwidth.

If the interior is at least partially divided by a flow guide into a pressure chamber and a cooking chamber, the fan and each antenna in the pressure chamber and the flow control in an intake of the fan has an opening and at least one edge at least one, in particular slit-shaped, air-permeable Unlocking opening, a pressure difference comes about, which allows a circulation of the cooking chamber, and each antenna from the cooking chamber and thus, for example. Gargutresten deposited in it is reasonably shielded.

If the means for guiding the microwaves comprise at least one microwave guide structure substantially outside the interior, with a section extending to at least one opening in the wall or wall part, and the section comprises a solid, conductive outer wall with a round, in particular circular, comprises cross-sectional shape, less heat passes through heat conduction from the interior. Such a reduction in heat conduction can not be easily achieved by reducing the diameter, because it is essentially determined by the microwave length. For a given diameter, the round shape gives the smallest possible cross-sectional area of the conductive outer wall.

When the means for guiding the microwaves comprises at least one microwave guide structure located substantially outside the interior with a portion extending at least to an opening in the wall portion, and the portion comprises a coaxial waveguide having an inner conductor and a conductor at the front the antenna arranged in the wall part, then the microwave energy can be conducted into the antenna with little loss. Means for coupling microwave energy from the waveguide into the antenna are not required. Another effect of using a coaxial waveguide is that the diameter of this waveguide may be smaller compared to a waveguide without compromising the propagation capability of the microwaves in the waveguide.

If the inner conductor extends to a waveguide encompassed by the microwave guide structure, it additionally acts as a receiving antenna for microwaves propagating in the waveguide. The use of a waveguide simplifies the coupling of a microwave generator or magnetron.

To further increase the range of application of the cooking appliance, at least one further device for treating food to be cooked may be provided, for example an electric or gas-operated heater, a heat exchanger, a moisture supply device and / or a moisture removal device. Thus, the opportunities offered by the presence of the fan to affect the cooking chamber climate, further exploited. The fan thus ensures not only a more even distribution of microwave energy, but also a more uniform temperature distribution and / or moisture distribution, so a substantially homogeneous cooking space climate, so that can be cooked at any point of the oven under the same conditions. This is special for commercial kitchens Importance, because only so reproducible high cooking qualities can be achieved in large quantities.

Figur 1:

eine Querschnittansicht eines erfindungsgemäßen Gargeräts von oben;

Figur 2:

eine Längsschnittansicht des Gargeräts der Figur 1;

Figur 3:

eine detaillierte perspektivische Ansicht eines hinteren Eckbereichs eines In- nenraums des Gargeräts der Figuren 1 und 2 von oben; und

Figur 4:

eine Querschnittansicht einer Mikrowellenleitstruktur aus dem Gargerät der Figuren 1-3.

Further features and advantages of the invention will become apparent from the following detailed description of an embodiment of the invention with reference to schematic drawings. Showing:

FIG. 1:

a cross-sectional view of a cooking appliance according to the invention from above;

FIG. 2:

a longitudinal sectional view of the cooking appliance of FIG. 1 ;

FIG. 3:

a detailed perspective view of a rear corner portion of an interior of the cooking appliance of Figures 1 and 2 from above; and

FIG. 4:

a cross-sectional view of a Mikrowellenleitstruktur from the cooking appliance of Figures 1-3 ,

One in the Figures 1 and 2 exemplified cooking appliance 1 comprises an interior whose height is determined essentially by the distance between a ceiling 2 and a bottom surface 3. The depth of the interior is determined by the distance between a cooking chamber door 4 and a rear wall 5. The cooking chamber door 4 closes a framed by a front wall (not shown) opening for placing and removing food (not shown) from. The width of the interior is determined by the distance between parallel left and right side walls 6, 7.

The interior is at least partially subdivided by a flow-guiding element 8 into a cooking chamber 9 and a pressure chamber 10. In the cooking chamber 9, the food is placeable. It can be provided in the cooking chamber 9, for example, a frame with slots for food support (not shown).

The left side wall 6 delimits the interior space from an installation space 11. Alternatively, the installation space can also be arranged behind the rear wall. In the illustrated configuration, however, it is easier to provide an electronic operating device on the front of the cooking appliance 1 next to the cooking chamber door 4, namely in the region of the installation space 11.

Like from the Figures 1 and 2 As can be seen, the side walls 6, 7 and the rear wall 5 extend in the vertical direction over the entire height of the interior. Likewise extend the ceiling 2, floor space 3 and side walls 6,7 over much of the depth of the interior. However, the left side wall 6 does not extend over the entire depth of the interior, because it passes over side wall parts 12, 13 in the rear wall 5 and the front wall with the cooking chamber 4. The side wall parts 12, 13 form bevels. They extend vertically over the entire height of the interior. In an alternative variant, bevels can also be arranged at the vertical ends of the side wall parts 12, 13.

At a side facing the interior of the rear side wall portion 12, which is referred to here as the front, two helical antennas 14, 15 are attached or fastened. When the microwave heating is switched on, microwaves are generated by respective magnetrons 16, 17 and guided via waveguide structures 18, 19 through the rear side wall part 12 to the helix antennas 14, 15.

From the FIG. 1 It can be seen that the rear wall 5 and the left side wall 6 intersect in respective, imaginary extensions behind the rear side wall portion 12. The space defined by the extensions and the rear side wall part 12, with approximately the shape of a cylinder having a triangular cross-sectional shape, belongs to the installation space 11. It provides additional space for the waveguide structures 18, 19.

In the FIG. 3 the upper helix antenna 14 is shown in more detail. It comprises a helical conductor 20 of approximately three turns about an imaginary longitudinal axis extending vertically from the front of the rear side wall portion 12. In alternative embodiments, more or fewer turns may be provided. By this configuration, circularly or at least elliptically polarized microwaves are emitted by the helical antenna 14. The radiation energy is mostly aligned along the longitudinal axis of the helical antenna 14. By making or coating the rear side wall portion 12 of a microwave reflective material, the majority of the microwave energy is emitted into the pressure space 10.

Because of this radiation characteristic, it is useful to have a plurality of helical antennas 14, 15 and to be arranged at different heights. Thus, microwave energy is fed into the pressure chamber 10 in all planes.

The helix antenna 14 may alternatively be provided to a rod-shaped antenna part 21 which extends parallel to the longitudinal axis of the helical antenna 14.

At the in FIG. 3 and 4 Cooking device shown is optionally the rod-shaped antenna part 21 or the helical antenna 14 by means of a screw detachably fastened to an arranged in the microwave guide structure 18 inner conductor 22. In an alternative embodiment (not shown), the rod-shaped antenna part 21 or the helix antenna 14 could also be designed as an integral continuation of the inner conductor 22. The inner conductor 22 forms with a round, solid, electrically conductive and cylindrical wall 23 and a likewise round coupling 24, a first portion 25 of the microwave guide structure 18 in the form of a coaxial waveguide. The circular, substantially circular, cross-sectional shape of the coupling 24 and the cylindrical wall 23 minimize thermal bridges between the pressure chamber 10 and the magnetron 16 connected to the microwave guide structure 18. In addition, microwaves in the coaxial waveguide are propagatable in the TEM mode. This fashion requires the smallest diameter for spreading. A further reduction of the diameter could be achieved in an alternative embodiment in that between a part of the inner conductor 22 and on the other hand the circular wall 23 and / or the inside of the coupling 24 is a substrate of dielectric material having a higher permittivity than air.

The first section 25 merges via a threaded bush 26 into a rectangular waveguide 27. On a first flat wall 28 of the rectangular waveguide 27, the (in the FIG. 4 not shown) magnetron 16 are fastened by means of a thread 29. In this case, an antenna of the magnetron 16 projects into the rectangular waveguide 27. The emitted microwaves are received by the inner conductor 22 and coupled into the first section 25. For this purpose, the inner conductor 22 extends into the rectangular waveguide 27. At its end located in the rectangular waveguide 27, the inner conductor 22 is fastened to a second flat wall 30 of the rectangular waveguide 27. In order to make this possible, the inner conductor 22 is bent in the interior of the rectangular waveguide 27. This also ensures that the part of the inner conductor 22 functioning as a receiving antenna absorbs more microwave energy.

Like from the Figures 3 and 4 As can be seen, 12 round openings through which the microwaves are guided into the interior, mounted in a flat central region of the rear side wall portion. In particular, the coupling 24 is clamped in such an opening. For this purpose, the coupling 24 has a flange 31, which is in the fastened state on the installation space side or rear side of the rear side wall part 12. At the front of the rear side wall portion 12 are a union nut 32 and a flat gasket 33. This creates a substantially gas-tight connection between the Alternatively, a gas-tight connection can also be realized in the form of a welded joint.

For fixing the inner conductor 22 and sealing the interior of the first portion 25 of the microwave guide structure 18, a disc 34 of dielectric material, e.g. steatite, Teflon or glass (such as Pyrex), is provided. The disc 34 has a groove 35 in which a (not shown) round seal can be arranged, on. The fact that the helical antenna 14 is fixedly attached to the rear side wall portion 12, this seal is easier to make than would be the case with a rotatable antenna.

Like from the Figures 1 and 2 shows, in the pressure chamber 10, a radial fan 36 is arranged. The radial fan 36 is driven by a drive shaft 37 from a motor 38 located in the installation space 11. The radial fan 36 sucks through an opening 39 in the flow guide 8 atmosphere, in particular air, steam and vapor, from the cooking chamber 9 and blows it off radially. The flow guide 8 leaves on at least one of its edges more openings 40 free. About these openings 40 in the edge region, the atmosphere passes back into the cooking chamber 9. From an injection device 41, steam, fat or flavorings in the promoted by the radial fan 36 atmosphere can be injected. A heater 42 having heating elements 43 disposed around the centrifugal fan 36 heats the atmosphere conveyed by the radial fan 36. Thus, in addition to the microwave heating yet another heater 42 is provided. This can, depending on the embodiment, be electric or gas-powered. It can also be designed in the form of a heat exchange device.

The flow guide 8 is made of microwave reflective material or coated with such a material. It may be provided in the flow guide 8 for microwave permeable, but airtight window. In any case, the microwave energy can reach the cooking chamber 9 via the openings 40 in the edge region of the flow-guiding member 8 from the pressure chamber 10. With this configuration, the pressure chamber 10 and the cooking chamber 9 form coupled resonators. Therefore, even with only two helical antennas 14, 15, a good distribution of the microwave energy, in particular during operation of the radial fan 36, can be achieved.

The distribution of the microwave energy is also improved by making the radial fan 36 at least partially made of microwave reflective material. It therefore acts as a mode mixer, so that the formation of standing waves in the pressure chamber 10 suppressed becomes. Due to the arrangement of the helical antennas 14, 15 laterally of the radial fan 36 on the front side of the side wall portion 12, which is oblique to the rear wall 5, the emitted microwave energy is directed mainly to the central region of the pressure chamber 10.

Thanks to the above-mentioned measures for better distribution of the microwave energy, it is sufficient that only at the rear side wall portion 12 helix antennas 14, 15 are arranged. In an alternative embodiment, however, antennas could also be arranged on the front side wall part 13.

By arranging the helical antennas 14, 15 on the rear side wall portion 12, which is oblique to the left side wall 6 and the rear wall 5, the installation space 11 is increased, without affecting the function of the pressure chamber 10 and the radial fan 36 and without the width of the To reduce cooking space 9. The overall width of the cooking appliance 1, however, remains relatively low. The magnetrons 16, 17 and waveguide structures 18, 19 find space in addition to several other facilities for the treatment of food in the installation room 11.

It is also the geometry of the cooking appliance, regardless of the type of antennas used and the presence of the radial fan, independent meaning, namely, when the cooking appliance an interior, which includes a cooking chamber for receiving food and by at least one wall and / or at least one Wall part is delimited, and comprises means for generating microwaves and for guiding the microwaves to at least one antenna, wherein at least a first wall passes over a wall part in a second wall, at least imaginary extensions of the two walls on the side facing away from the interior rear side of the wall part cut, and at least one of the antennas attached to the interior facing the front of the wall part or attachable. This geometry leads to a particularly compact design.

The features of the invention disclosed in the foregoing description, the claims and the drawings may be essential both individually and in any combination for the realization of the invention in its various embodiments.

LIST OF REFERENCE NUMBERS

1

Cooking appliance

2

blanket

3

floor area

4

oven door

5

rear wall

6

Left sidewall

7

Right side wall

8th

flow directing

9

oven

10

pressure chamber

11

installation space

12

Rear side wall part

13

Front side wall part

14

Upper helix antenna

15

Lower helical antenna

16

Upper magnetron

17

Lower magnetron

18

Upper waveguide structure

19

Lower waveguide structure

20

Spiral-shaped conductor

21

Rod-shaped antenna part

22

inner conductor

23

Round wall

24

clutch

25

1st section

26

threaded bushing

27

Rectangular waveguide

28

1. Wall of the rectangular waveguide

29

thread

30

2. Wall of the rectangular waveguide

31

flange

32

Nut

33

gasket

34

disc

35

groove

36

radial fan

37

drive shaft

38

engine

39

opening

40

Openings in the edge area

41

Injector

42

heater

43

heating elements

Claims (9)

Cooking appliance (1), comprising: an interior comprising a cooking chamber (9) for receiving food to be cooked; and means (16, 17, 18, 19) for generating microwaves and guiding the microwaves to at least one circularly or elliptically polarized antenna (14, 15) arranged to direct the microwaves along a direct path into the interior space radiates, characterized in that in the interior of a separate from the antenna (14,15), at least partially reflecting microwave fan (36) for circulation of atmosphere in the interior and for equalization of the microwave energy distribution in the interior is rotatably arranged. Cooking appliance according to claim 1, characterized in that
the interior is delimited by at least one wall (2, 3, 5, 6, 7) and / or at least one wall part (12, 13), and
on one facing the interior front of one of the walls (2,3,5,6,7) or one of the wall parts (12,13), the antenna (14,15) is arranged, in particular at least one first wall (5) via a Wall part (12) merges into a second wall (6),
Extensions of the two walls (5,6) on a side facing away from the interior rear side of the wall part (12) intersect and
the antenna (14,15) is attached to an interior facing front side of the wall part (12). Cooking appliance according to claim 2, characterized in that
the fan wheel (36) is arranged on the first or the second wall (5, 6),
and or
at least one of the first and second walls (5, 6) forms a rear wall or sidewall of the interior, and / or
the extensions of the two walls (5,6) represent imaginary extensions. Cooking appliance according to one of the preceding claims, characterized in that at least two antennas (14,15) on different levels, preferably with each other, in the cooking appliance (1) are arranged, in particular an antenna (14), above the rotational axis of the fan wheel (36) and the other antenna (15) below the axis of rotation of the fan wheel (36) is located, and / or
the fan wheel (36) is designed as a radial fan. Cooking appliance according to one of the preceding claims, characterized in that each antenna (14, 15) comprises a conductor (20) with at least one winding extending around an aligned or orientable longitudinal axis in the direction of the interior, in particular a helical antenna. Cooking appliance according to one of the preceding claims, characterized in that the interior space is at least partially divided by a flow-guiding element (8) into a pressure chamber (10) and the cooking chamber (9),
the fan wheel (36) and each antenna (14, 15) are located in the pressure chamber (10), and the flow guide element (8) has an opening (39) in an intake area of the fan wheel (36) and at least one edge at least one, in particular slit-shaped, air-permeable opening (40) leaves free. Cooking appliance according to one of claims 2 to 6, characterized in that the means for guiding the microwaves at least one microwave guide structure (18,19) located substantially outside the interior with a portion (25) extending to at least one opening in the wall (2,3,5,6,7) or the wall part (12) extend, wherein
in particular, the section (25) has a solid, conductive outer wall (23, 24) with a round, in particular circular, cross-sectional shape and / or a coaxial waveguide with an inner conductor (22) which is connected to a conductor (20) on the front side Wall or the wall portion (12) arranged antenna (14,15) is connectable or connected comprises. Cooking appliance according to claim 7, characterized in that
the inner conductor (22) extends up to a waveguide (27) encompassed by the microwave guide structure (18, 19), in which, in particular, at least one antenna extends at least one magnetron (16, 17). Cooking appliance according to one of the preceding claims, characterized in that at least one further device (41, 42, 43) is provided for the treatment of food to be cooked is, where
the further device in particular comprises an electric or gas-operated heater (42, 43), a heat exchanger, a moisture removal device and / or a moisture supply device.

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