Combination oven with ring mode suppressor

Abstract

The invention relates to a combination cooking appliance (10) for cooking food, comprising a housing (13) surrounding a cooking chamber and a cooking chamber door that can assume an open and a closed state, wherein in the closed state the cooking chamber door completely covers a loading opening of the cooking chamber, wherein a groove (34) is provided in which a cooking chamber seal (32) is received to seal the loading opening of the cooking chamber in the closed state, wherein an annular mode suppressor (36) is provided which is arranged in the groove (34) below the cooking chamber seal (32), wherein the annular mode suppressor (36) has an alternating structure of at least two materials with different dielectric properties.

Description

[0001] The invention relates to a combination cooking appliance with a ring mode suppressor.

[0002] In professional and commercial kitchens, combination cooking appliances are used, which are capable of cooking food in a variety of ways within the cooking chamber of the combination cooking appliance. In addition to traditional cooking methods using hot air and / or steam, modern combination cooking appliances also frequently utilize microwave radiation. Magnetrons or semiconductor components can be used as microwave sources to feed microwaves into the cooking chamber.

[0003] Generally, microwaves, steam, and hot air should be prevented from escaping from the cooking chamber during the cooking process. Microwave leakage, in particular, must be avoided to keep radiation exposure in the immediate vicinity as low as possible, especially below specified limits, e.g., 50 mW per square centimeter at a distance of five centimeters from the cooking appliance.

[0004] Due to the aforementioned constraints, combination cooking appliances are typically equipped with cooking chamber seals that seal out steam and / or hot air, and microwave seals or traps that dampen or minimize the escape of microwave radiation.

[0005] For example, DE 10 2014 107 581 A1 discloses a cooking appliance that provides a microwave seal and an additional cooking chamber seal for sealing the loading opening of the cooking chamber. A rubber seal is arranged around the loading opening as the cooking chamber seal, which interacts with a cooking chamber door. A quarter-wave trap is provided for the microwave seal to prevent microwave radiation from escaping from the cooking chamber. Both seals are spatially separated from each other to minimize negative interactions that would result in increased microwave leakage.

[0006] Furthermore, DE 10 2004 052 798 A1 discloses a cooking oven for treating food using microwave radiation. The cooking oven comprises the following: at least one cooking chamber; at least one frame that at least partially encloses at least one loading opening of the cooking chamber; at least one door for closing the loading opening, wherein the door, when closed, completely covers the loading opening and partially covers a front side of the frame; and a microwave seal that is attached or attachable to the front side of the frame. When the door is closed, the microwave seal is arranged next to an outer peripheral surface or an outer peripheral surface section of the door.

[0007] Another microwave oven is described in DE 102 56 624 A1. This comprises a body and a door, which includes a closed door frame and a viewing window arranged on the door frame. The door further comprises a metal throttle profile arranged in the door frame, which has a circumferential, essentially U-shaped base body and a frame. The frame is arranged on the inner side wall of the U-shaped base body and covers the opening of the U-shaped base body facing the body when the door is closed, except for a first gap between the free edge of the frame and the outer side wall of the U-shaped base body. The viewing window covers the frame in such a way that the edge of the viewing window and the outer side wall of the U-shaped base body of the throttle profile form a second gap.

[0008] Given the increasing use of such combination cooking appliances, efforts are being made to further improve the microwave seals used to minimize the leakage of microwave radiation from the cooking chamber without compromising the sealing effect of the cooking chamber seal against hot air and steam. Nevertheless, care must be taken to ensure that the different seals, i.e., the microwave seal and the cooking chamber seal, do not interfere with each other during operation of the cooking appliance.

[0009] In this respect, it is the object of the present invention to provide a combination cooking appliance that effectively seals the cooking chamber against steam and hot air as well as enabling effective sealing against microwave radiation from the cooking chamber.

[0010] The object is achieved according to the invention by a combination cooking appliance for cooking food, comprising a housing that surrounds a cooking chamber and a cooking chamber door that can assume an open and a closed state. In the closed state, the cooking chamber door completely covers a loading opening of the cooking chamber. Furthermore, a groove is provided in which a cooking chamber seal is received in order to seal the loading opening of the cooking chamber when closed. In addition, a ring mode suppressor is provided, which is arranged in the groove below the cooking chamber seal, wherein the ring mode suppressor has an alternating structure made of at least two materials with different dielectric properties.

[0011] The invention is based on the finding that a cooking chamber seal, which seals the cooking chamber against steam and hot air, can lead to a change or disturbance in the electromagnetic field during microwave operation of the combination cooking appliance. This change or disturbance can take the form of ring modes and can be understood as a periodic change or disturbance in the electromagnetic field, which locally amplifies the electromagnetic field at the cooking chamber seal, which can promote and under certain circumstances even amplify the escape of microwave radiation. This is due to the fact that the cooking chamber seal is usually arranged adjacent to the cooking chamber door in order to seal the door gap between the cooking chamber door and the housing, so that the ring modes can escape into the environment via the door gap without obstruction.

[0012] Ring modes are defined as constructive interference of microwaves that form semicircular electromagnetic fields emanating from their point of origin. These fields originate at the cooking chamber seal, which seals the loading opening, causing the ring modes to occur along the door gap between the cooking chamber door and the housing. The door gap and the cooking chamber seal that seals the door gap do not pose an obstacle to the ring modes, so leakage or escape of microwave radiation from the cooking chamber occurs at these points.

[0013] Furthermore, it was recognized that the ring modes cannot be effectively attenuated by a quarter-wave trap near the cooking chamber seal. In the worst case, a quarter-wave trap in the area of ​​the cooking chamber seal, for example, by tuning the groove of the cooking chamber seal to a geometric depth of approximately one-quarter the electrical length of the wavelength used in the cooking chamber, can also generate interference in the form of ring modes or amplify already existing ring modes. In this respect, the ring mode suppressor is not equivalent to a classic quarter-wave trap, which is standard for microwave seals in common combination cooking appliances.

[0014] Wavelength refers in particular to the wavelength in a vacuum (or approximately in air).

[0015] Electrical length is the distance traveled by an electromagnetic wave in a propagation medium, e.g. in a ring mode suppressor.

[0016] The proposed ring mode suppressor makes it possible to easily suppress the periodic disturbances in the electromagnetic field generated at the cooking chamber seal in the form of ring modes, i.e., to reduce or attenuate their intensity. This allows the overall leakage of microwave radiation from the cooking chamber to be minimized. Suppression means that the intensity of the ring modes is reduced by at least half, relative to the original intensity of the ring modes without the ring mode suppressor. Preferably, the intensity of the ring modes is reduced by at least 75%.

[0017] For this purpose, the ring mode suppressor according to the invention has an alternating structure consisting of at least two materials with different dielectric properties.

[0018] Different dielectric properties of the at least two materials mean that they differ in at least one parameter relating to their dielectric properties. Dielectric properties primarily include the parameters of the dielectric constant or permittivity, the dielectric loss factor, the susceptibility, and the polarization. These parameters reflect the material's response to the application and permeability of an electromagnetic field.

[0019] The core idea of ​​the present invention is to provide a periodic structure made of two different materials with differing dielectric properties to suppress the ring modes that arise at the cooking chamber seals during microwave operation. In this way, the leakage of microwave radiation from the cooking chamber into the environment can be (further) reduced in a simple manner.

[0020] In principle, the terms “materials with different dielectric properties” and “different dielectric materials” can be used synonymously.

[0021] Furthermore, the arrangement of the ring mode suppressor according to the invention is particularly space-saving, as it is located in the groove below the cooking chamber seal and thus does not take up any additional space in the combination cooking appliance, as a groove is typically already provided for the cooking chamber seal. Therefore, the ring mode suppressor can be arranged in the same groove as the cooking chamber seal, saving space. It is also conceivable that the ring mode suppressor can be easily retrofitted to existing cooking appliances, especially if the cooking chamber seal is replaced.

[0022] A combination cooking appliance for cooking food within the meaning of the invention is understood to be a cooking appliance used in professional or commercial kitchens. It is designed for professional use and is also configured to cook food using a combination of different methods. These include cooking using hot air, steam, and microwave radiation.

[0023] According to a first aspect of the invention, the alternating structure and the cooking chamber seal are designed as a single piece. In this way, the advantages of the ring mode suppressor and those of a conventional cooking chamber seal can be combined in the smallest possible space. This enables a particularly simple design of the combination of cooking chamber seal and ring mode suppressor in a common groove provided for this purpose. In particular, a cooking chamber seal provided as a spare part can already have the ring mode suppressor integrated.

[0024] A further aspect of the invention provides that the ring mode suppressor surrounds the feed opening along an extension direction, in particular wherein the at least two materials with different dielectric properties are arranged alternately along the extension direction.

[0025] The direction of extension refers to the direction of the ring mode suppressor around the loading opening. This extension corresponds to the extension of the groove that accommodates the cooking chamber seal. The groove advantageously completely surrounds the circumference of the loading opening. Therefore, the ring mode suppressor can also be enclosed and extend around the loading opening in a frame-like manner. The ring mode suppressor therefore completely surrounds the circumference of the loading opening. The arrangement of at least two materials with different dielectric properties along the direction of extension enables the loading opening to be surrounded by a periodic structure of the at least two dielectric materials, thus effectively suppressing the leakage of microwave radiation.

[0026] The at least two dielectric materials can in particular be arranged equidistant from one another, in particular along the direction of extension.

[0027] According to another aspect of the invention, there is a permittivity difference between the at least two materials with different dielectric properties in a range from 0.3 to 30, preferably from 0.5 to 5, particularly preferably from 1.0 to 2, based on the relative permittivity of the materials.

[0028] Consequently, a dielectric jump exists between the two dielectric materials in the form of a permittivity difference. Due to the periodic arrangement of the two materials in the alternating structure, the ring mode suppressor also exhibits a periodic arrangement of dielectric jumps along its alternating structure, creating a dielectric jump from one material to the next at periodic intervals along the groove. It has been found that the dielectric jumps, which repeat periodically along the groove, lead to the desired suppression of the ring modes.

[0029] The relative permittivity refers to the relative dielectric constant or the synonymous relative permittivity, which describes the dimensionless ratio of the permittivity ε to the permittivity ε0 of the vacuum.

[0030] Another aspect of the invention provides that one dielectric material is air. This allows for a particularly simple design of the alternating structure made of at least two materials with different dielectric properties. Air offers the particular advantage that it can be particularly easily incorporated into the alternating structure, for example, in the form of cavities, recesses, or slots. In this respect, the cooking chamber seal can be partially slotted or provided with recesses that, in particular, face a bottom of the groove.

[0031] According to a further aspect of the invention, one dielectric material is air, whereas the other dielectric material is selected from the group consisting of silicones, rubbers, glass fibers, and silicone rubbers. Such materials have proven particularly advantageous for use as dielectric materials in combination with air in the alternating structure of the ring mode suppressor.

[0032] The aforementioned materials, or any materials considered as dielectric materials, must withstand the temperatures prevailing in the cooking chamber during operation of the combination cooking appliance. For this reason, the aforementioned materials are particularly suitable for use as dielectric materials in combination with air.

[0033] A further aspect of the invention provides that the alternating structure is formed from at least three dielectric materials, of which one dielectric material is air, and the other two dielectric materials are each selected from the group consisting of silicones, rubbers and glass fibers as well as silicone rubbers.

[0034] The combination of multiple dielectric materials offers the advantage of creating different types of dielectric jumps within the ring mode suppressor—i.e., dielectric jumps that differ from one another. If the alternating structure is formed from at least three dielectric materials, a total of two different dielectric jumps result in the smallest repeating unit of the periodic structure, thus creating two different types of dielectric jumps within the alternating structure. In this way, the alternating structure can achieve a broader bandwidth and cover a broad spectrum of microwave radiation.

[0035] Another aspect of the invention provides that a first dielectric material is completely encased by a second dielectric material, creating a dielectric hybrid element. Several dielectric hybrid elements, together with air as the third dielectric material, form the alternating structure.

[0036] In other words, a first dielectric material is encapsulated by a second dielectric material, which can result in various advantages. In particular, such a configuration allows the use of a material as the first dielectric material that enables a particularly large dielectric jump, for example through a particularly high or low dielectric constant with respect to the second dielectric material, but which at the same time is not stable with respect to the conditions prevailing in the cooking chamber, such as high humidity and / or high temperatures. In this respect, the first dielectric material is protected by the second dielectric material. In this respect, the arrangement described here enables the use of materials that are more sensitive to steam and high temperatures, which could otherwise not be integrated into the alternating structure of the ring mode suppressor.

[0037] The second dielectric material that surrounds the first dielectric material is therefore preferably made of a material that can withstand the high temperatures and high humidity in the cooking chamber.

[0038] A further aspect of the invention provides that the plurality of dielectric hybrid elements are cuboid-shaped, with the dielectric hybrid elements being interrupted by air slots to form the alternating structure. Such a structure can be accommodated in the groove in a particularly space-saving manner and takes up little installation space. Furthermore, this allows for a simple design of an alternating structure that effectively suppresses the ring modes at the cooking chamber seal.

[0039] Advantageously, with respect to the hybrid element, the first dielectric material is a silicone and the second dielectric material is a rubber.

[0040] It is particularly advantageous that both materials are selected in such a way that a particularly large dielectric jump occurs between the two materials.

[0041] According to a further aspect, a quarter-wave trap is provided, which surrounds the loading opening when closed. A quarter-wave trap is a simple and proven method for preventing microwave radiation from escaping from the cooking chamber. The quarter-wave trap is provided in addition to the ring mode suppressor.

[0042] In principle, the quarter-wave trap can be designed in any way, as long as it has a recess facing the loading opening with a geometric depth corresponding to an electrical length of approximately one-quarter the wavelength of the microwave radiation used in the cooking chamber. The quarter-wave trap also works synergistically with the ring mode suppressor, as both attenuate different types of microwave radiation. The ring modes can be captured by the ring mode suppressor, and the remaining microwave radiation by the quarter-wave trap, effectively preventing or further reducing the escape of microwave radiation into the environment.

[0043] In another aspect of the invention, the ring mode suppressor is arranged between the quarter-wave trap and the cooking chamber when closed. This arrangement enables a particularly effective reduction of microwave radiation in the area of ​​the loading opening. The quarter-wave trap reduces the microwave radiation escaping from the cooking chamber, whereas the ring mode suppressor suppresses the ring modes generated by the microwave radiation at the cooking chamber seal. The combination results in a particularly low emission of microwave radiation from the cooking chamber to the environment.

[0044] In principle, any arrangement of ring mode suppressor and quarter-wave trap is possible in the combination cooking appliance, as long as the above-mentioned boundary conditions are met.

[0045] For example, the ring mode suppressor and the quarter-wave trap can both be provided together in the cooking chamber door or together in the edge area of ​​the cooking cabinet along the loading opening.

[0046] However, it is also conceivable that one of the two components is on the cooking chamber door and the other component is on the cooking chamber housing.

[0047] Particularly advantageously, the quarter-wave trap is located in the cooking chamber door, and the ring mode suppressor is located on the cooking chamber housing along the loading opening. Thus, when the combination cooking appliance is closed, the ring mode suppressor is located between the quarter-wave trap and the cooking chamber, in accordance with the aforementioned aspect.

[0048] When closed, the ring mode suppressor and the quarter-wave trap are particularly advantageously arranged laterally offset from each other. This arrangement enables particularly effective attenuation of the microwave radiation.

[0049] Further features and advantages of the invention will become apparent from the following description and the accompanying drawings, to which reference is made. In the drawings: - Fig. 1 is an isometric view of a prior art combination cooking appliance; - Fig. 2 an isometric view of a combination cooking appliance according to the invention with a housing-side ring mode suppressor; - Fig. 3 an isometric view of a combination cooking appliance according to the invention with a door-side ring mode suppressor; - Fig. 4 a detailed representation of the combination cooking appliance according to the invention from Fig. 2; - Fig. 5 a schematic plan view of detail A from Fig. 4; - Fig. 6 a schematic plan view of detail B from Fig. 4; - Fig. 7 a schematic cross-sectional view along the section plane AA of Fig. 6 according to a first embodiment of the ring mode suppressor; - Fig. 8 a schematic cross-sectional view along the section plane AA of Fig. 6 according to a second embodiment of the ring mode suppressor; - Fig. 9 a schematic cross-sectional view along the section plane AA of Fig. 6 according to a third embodiment of the ring mode suppressor; - Fig. 10 a schematic cross-sectional view along the section plane BB of Fig. 9; - Fig. 11 an isometric view of the combination cooking appliance according to the invention from Fig. 2 in a closed state; - Fig. 12 a schematic plan view of detail C from Fig. 11; - Fig. 13 an isometric cross-sectional view along the section plane CC Fig. 12; - Fig. 14A and Fig. 14B are diagrams of 2D simulations of the electromagnetic field along the circumference of the cooking chamber door from Fig. 2, in Fig. 14A without ring mode suppressor and in Fig. 14B with ring mode suppressor; and - Fig. 15 a diagram with data curves of the 2D simulation from the Fig. 14A and Fig. 14B.

[0050] Fig. 1 shows a combination cooking appliance 10 from the prior art.

[0051] The combination cooking appliance 10 has a cooking chamber door 12 and a housing 13, wherein the cooking chamber door 12 is pivotally attached to the housing 13 so that the cooking chamber door 12 can assume a closed and an open state.

[0052] The cooking chamber door 12 has a central door section 14, which is formed from at least one pane 16, in particular a glass pane, and a perforated plate 18. The structure of the door section 14 will be described later with reference to Fig. 4 explained in detail.

[0053] The housing 13 defines a cooking chamber 20, which is accessible from outside the combination cooking appliance 10 through a loading opening 22 in the housing 13. Food to be cooked can be introduced into or removed from the cooking chamber 20 via the loading opening 22.

[0054] The loading opening 22 is completely covered by the cooking chamber door 12 when it is closed.

[0055] The combination cooking appliance 10 has an inner box 24 and an outer box 26 connected to the inner box 24. The inner box 24 defines the cooking chamber 20 and has an opening in the form of the loading opening 22.

[0056] The outer box 26 has a housing-side edge region 28 that adjoins the loading opening 22 and surrounds it in a closed, frame-like manner. Consequently, the periphery of the loading opening 22 is essentially completely surrounded by the housing-side edge region 28.

[0057] The cooking chamber door 12 has a door-side edge region 30 corresponding to the housing-side edge region 28, wherein in the closed state of the cooking chamber door 12, the housing-side edge region 28 and the door-side edge region 30 lie on top of one another and seal the cooking chamber 20 from the environment.

[0058] The combination cooking appliance 10 is used to cook food placed in the cooking chamber 20. For this purpose, the combination cooking appliance 10 has a microwave source, a steam generator, and a hot air source (not shown here).

[0059] Typically, the hot air source and / or steam generator are used to adjust the cooking climate in the cooking chamber 20, which influences the cooking of the food. The microwave source can generate microwaves that introduce (additional) energy into the food to cook it faster or more precisely. Alternatively, microwave radiation can be used to control the cooking process or record cooking parameters, for example, to determine the cooking chamber load, which is generally referred to as "sensing."

[0060] In principle, the combination cooking appliance 10 can cook the food either using microwave radiation alone or using the cooking chamber climate alone. Of course, both methods can also be used in combination, i.e., simultaneously or in parallel.

[0061] In Fig. 2 shows a combination cooking appliance 10 according to the invention. This also has the features described for the combination cooking appliance in Fig. 1 already described. For an explanation of these features, please refer to the above description.

[0062] Compared to the Fig. 1 shown combination cooking appliance 10 from the prior art, the Fig. The combination cooking appliance 10 according to the invention shown in Figure 2 has a cooking chamber seal 32 which is received in a groove 34 in order to seal the loading opening 22 of the cooking chamber 20 in the closed state.

[0063] The groove 34 with the cooking chamber seal 32 accommodated therein is provided in the edge region 28 on the housing side and completely surrounds the loading opening 22.

[0064] The groove 34 and the cooking chamber seal 32 together form a ring mode suppressor 36. Details of the ring mode suppressor 36 are explained in detail below.

[0065] While the cooking chamber seal 32 is designed to seal the cooking chamber 20 against steam and heat, the ring mode suppressor 36 is provided to suppress disturbances or changes in the electromagnetic field in the form of ring modes that occur at the cooking chamber seal 32 during microwave operation of the combination cooking appliance 10.

[0066] Additionally, a quarter-wave trap 38 is provided on the cooking chamber door 12, extending along the door-side edge region 30. When the combination cooking appliance 10 is closed, the quarter-wave trap 38 extends along the door-side edge region 30 and surrounds the loading opening 22 in a closed, frame-like manner. The quarter-wave trap 38 serves to prevent microwave radiation generated during microwave operation from escaping from the cooking chamber 20 into the environment, thus reducing microwave leakage.

[0067] According to an alternative embodiment, the position of the ring mode suppressor 36 and that of the quarter-wave trap 38 can be interchanged. In other words, the quarter-wave trap 38 can be arranged in the housing-side edge region 28, and the ring mode suppressor 36 can be arranged together with the cooking chamber seal 32 and the groove 34 in the door-side edge region 30. This is shown by way of example in Fig. 3 shown.

[0068] Preferably, the ring mode suppressor 36 is provided together with the groove 34 and the cooking chamber seal 32 on the housing-side edge region 28 and the lambda quarter trap 38 on the door-side edge region 30, as well as in Fig. 2 is shown and explained accordingly.

[0069] In the following, the design of the quarter-lambda trap 38 according to the embodiment in Fig. 2 described in more detail.

[0070] A detailed illustration of the structure of the lambda quarter trap 38 in the cooking chamber door 12 is shown in the Fig. 4 and Fig. 13, to which reference is made below.

[0071] In the embodiment shown, the quarter-wave trap 38 is designed as a cup-shaped section 40 that, when the combination cooking appliance 10 is closed, extends like a frame around the loading opening 22. The cup-shaped section 40 has an open side 42 that is oriented toward the loading opening 22 of the cooking chamber 20.

[0072] Opposite the open side 42, a base 44 of the cup-shaped section 40 is provided, to which an outer wall 46 and an inner wall 48 are connected, both aligned parallel to each other. The designations "outer" and "inner" refer to the respective positions relative to the geometric center of the cooking chamber door 12.

[0073] In the embodiment according to the Fig. 4 and Fig. 13, the pot-shaped section 40 has a U-shaped cross section defined by the outer wall 46, the inner wall 48 and the bottom 44. The U-shaped cross section is in Fig. 13 and is explained in detail below.

[0074] Basically, the pot-shaped section 40 represents the actual quarter-wave trap 38, which prevents the microwaves fed into the cooking chamber 20 from escaping from the cooking chamber 20.

[0075] Furthermore, the lambda-quarter trap 38 has a plurality of tooth elements 50 which are spaced apart from one another by slots 52, wherein the tooth elements 50 extend laterally outwards from the feed opening 22 in the closed state, so that the tooth elements 50 protrude into the open side 42 of the pot-shaped section 40 or are associated with it, which in Fig. 13 is also shown.

[0076] The toothed elements 50 are arranged along the cup-shaped section 40, forming a toothed ring 54. More precisely, the toothed ring 54 is designed as a comb-like structure that, when the combination cooking appliance 10 is closed, encloses the loading opening 22 in a frame-like manner. The individual toothed elements 50 each have a side facing the bottom 44 of the cup-shaped section 40.

[0077] In addition, the gear ring 54, viewed from above, extends along a rectangular basic shape which is rounded at each of the four corners.

[0078] The ring gear 54 surrounds, as can be seen in particular from Fig. 13, further comprising the periphery of a flat sheet metal element 58, in particular the perforated sheet metal 18, wherein the sheet metal element 58 completely covers the central door section 14. In particular, the toothed ring 54 is provided at a deformed end of the sheet metal element 58.

[0079] In this respect, the plurality of tooth elements 50 extend laterally outward from the circumference of the sheet metal element 58.

[0080] The cup-shaped section 40 can also be attached to the circumference of the sheet metal element 58, so that the inner wall 48 extends from the sheet metal element 58 at a (substantially) right angle.

[0081] The inner wall 48 and the sheet metal element 58 meet in a common transition section 59. Specifically, the transition section 59 is formed as a common edge.

[0082] In particular, the cup-shaped section 40 is attached to the sheet metal element 58 in the area in which the toothed ring 54 is provided on the sheet metal element 58.

[0083] Consequently, the sheet metal element 58, the inner wall 48 and the tooth elements 50 meet at the transition section 59.

[0084] Preferably, the sheet metal element 58, the cup-shaped section 40 and the tooth elements 50 are designed together in one piece.

[0085] Particularly preferably, the aforementioned elements are made of a metallic material or an alloy.

[0086] It is also conceivable that the sheet metal element 58, the cup-shaped section 40 and the tooth elements 50 are welded together in the transition section 59.

[0087] The perforated sheet 18 is provided in the central door section 14, which is covered by the sheet element 58.

[0088] Preferably, the perforated plate 18 is formed integrally with the sheet metal element 58, and the perforated plate 18 represents a central portion of the sheet metal element 58, so that the periphery of the perforated plate 18 is surrounded by the sheet metal element 58.

[0089] Alternatively, the sheet metal element 58 may have a central recess into which the perforated sheet 18 is inserted and welded to the sheet metal element 58 at the edge.

[0090] The perforated plate 18 serves, in particular, as an additional microwave seal and prevents the microwave radiation fed into the cooking chamber 20 from escaping through the central door section 14 into the surrounding area. At the same time, this ensures that the cooking chamber 20 can be viewed when the cooking chamber door 14 is closed.

[0091] Furthermore, when closed, the quarter-wave trap 38, the perforated plate 18, and the sheet metal element 58 are separated from the cooking chamber 20 by a microwave-transparent cover. This cover is arranged in the area of ​​the central door section 14 and is formed by the pane 16.

[0092] In particular, the disc 16 can be attached to the quarter-wave trap 38 via at least one adhesive point.

[0093] The tooth elements 50 are described below using detail A from Fig. 4, which shows an enlarged section of the door-side edge area 30.

[0094] As can be seen from detail A in Fig. 5, the tooth elements 50 have a substantially rectangular basic shape, wherein the tooth elements 50 pointing outwards in the direction of the corners of the cooking chamber door 12 preferably have an inwardly tapering basic shape (not shown here).

[0095] Alternatively, all tooth elements 50 can be straight. This is also the case in Fig. 5 shown.

[0096] The ring mode suppressor 36 is described below using detail B from Fig. 4 explained in more detail, which in Fig. 6 is shown.

[0097] In detail B in Fig. 6 is an enlarged section of the edge area 28 on the housing side, in which the cooking chamber seal 32 adjoining the loading opening 22 is arranged.

[0098] As already explained above, the cooking chamber seal 32 is accommodated in the groove 34. The ring mode suppressor 36 is provided below the cooking chamber seal 32.

[0099] Fig. Figure 6 shows a top view of the housing-side edge area 28, i.e., a top view of the cooking chamber seal 32, so that the underlying ring mode suppressor 36 is not directly visible. It is therefore indicated by dashed lines.

[0100] The ring mode suppressor 36 comprises at least two materials with different dielectric properties. Specifically, the ring mode suppressor 36 is Fig. 6 is formed by a first dielectric material 60 and a second dielectric material 62, which together form an alternating structure 63. In this respect, the materials 60, 62 form the smallest asymmetric unit of the alternating structure 63.

[0101] Consequently, the materials 60, 62 repeat along the extension direction of the groove 34. In particular, the alternating structure 63 extends along the extension direction of the groove 34 around the loading opening 22. The alternating structure 63 is preferably closed, frame-like, and essentially completely surrounds the circumference of the loading opening 22.

[0102] For example, one dielectric material may be air and the other dielectric material may be selected from the group consisting of silicones, rubbers and glass fibers as well as silicone rubbers.

[0103] In particular, the materials with different dielectric properties are selected such that a permittivity difference exists between the two materials. For example, the permittivity difference between the two materials can be in a range from 0.3 to 30, preferably from 0.5 to 5, particularly preferably from 1.0 to 2, based on the relative permittivity of the materials.

[0104] In the present case, the first dielectric material 60 is cuboid-shaped and the second dielectric material 62 forms a gap between two first dielectric materials 60.

[0105] The gap can, in particular, be an air slot 64. Consequently, the second dielectric material 62 is air. The first dielectric material 60 is thus selected from the group consisting of silicones, rubbers, glass fibers, and silicone rubbers.

[0106] In Fig. Figure 7 is a cross-sectional view along section plane AA of Fig. 6 according to a first embodiment.

[0107] It can be seen that the alternating structure 63 extends horizontally and contacts the bottom of the groove 34.

[0108] In the cross-sectional view in Fig. 7, the cuboid-shaped first dielectric materials 60 are particularly clearly visible. These are arranged in a periodically repeating manner along the extension direction of the groove 34 and are spaced from each other by the second dielectric material 62.

[0109] In the example shown, the second dielectric material 62 is arranged in the form of air slots 64 between the first cuboid-shaped dielectric elements 60.

[0110] The alternating structure 63 is arranged in the groove 34 below the cooking chamber seal 32 and contacts with its upper side the underside of the cooking chamber seal 32, wherein the cooking chamber seal 32 is closed and runs above the alternating structure 63 along the extension direction.

[0111] The cooking chamber seal 32 thus spatially separates the alternating structure 63 from the environment, in particular the cooking chamber 20, so that the alternating structure 63 is not contaminated by the food being cooked.

[0112] For example, the cooking chamber seal 32 can be designed as a rubber lip or a sealing lip in order to seal the cooking chamber 20 against steam and hot air when closed.

[0113] As in Fig. 7 by means of the different hatching, the cooking chamber seal 32 and the first dielectric material 60 can consist of different materials.

[0114] In principle, the material for the cooking chamber seal 32 is not restricted and any material known in the art for seals can be used as long as it is elastic and withstands the cooking chamber climate.

[0115] The cooking chamber seal 32 can be attached to the alternating structure 63. For example, the top side of the alternating structure 63 can be glued to the bottom side of the cooking chamber seal 32.

[0116] However, it is also conceivable that the cooking chamber seal 32 and the alternating structure 63 are merely loosely placed on top of one another, wherein the cooking chamber seal 32 presses the underlying alternating structure 63 into the groove 34, so that the latter is held captively in the groove 34 by the cooking chamber seal 32.

[0117] According to a second embodiment as shown in Fig. As shown in Figure 8, the cooking chamber seal 32 and the alternating structure 63 can be formed as a single piece. In this variant, the cooking chamber seal 32 and the alternating structure 63 are made of the same material, for example, a material as previously proposed for the first dielectric material 60.

[0118] Fig. 9 shows another embodiment of the alternating structure 63.

[0119] The first dielectric material 60 is surrounded by the second dielectric material 62, so that a dielectric hybrid element 65 is created.

[0120] As in Fig. 9, a plurality of dielectric hybrid elements 65 together with air as the third dielectric material 66 form the alternating structure 63. The third dielectric material 66 can be arranged in the form of air slots 64 between the dielectric hybrid elements 65.

[0121] The other two dielectric materials 60, 62 are each selected from the group consisting of silicones, rubbers, silicone rubbers and glass fibers.

[0122] Preferably, the first dielectric material 60 is a silicone and the second dielectric material 62 is a rubber.

[0123] Furthermore, the plurality of dielectric hybrid elements 65 are each cuboid-shaped and interrupted by air slots 64, so that an alternating structure 63 consists of a total of three dielectric elements 60, 62, 66.

[0124] Further details of the hybrid element 65 are shown in the cross-sectional view of such a hybrid element 65 in Fig. 10 shown.

[0125] The hybrid element 65 comprises a core consisting of the first dielectric material 60, which is surrounded by the second dielectric material 62. Specifically, the first dielectric material 60 is encapsulated by the second dielectric material 62, which forms a shell that completely covers the first dielectric material 60.

[0126] In addition, the hybrid element 65 is attached on one side to the cooking chamber seal 32 via a contact point 68.

[0127] For example, the cooking chamber seal 32 can be glued to the hybrid element 65 via the contact point 68.

[0128] However, it is also conceivable that the hybrid elements 65 are arranged loosely in the groove 34 and are held by the cooking chamber seal 32 pressed into the groove 34.

[0129] Alternatively, the second dielectric material 62 and the cooking chamber seal 32 may be formed as a single piece.

[0130] In this variant, the second dielectric material 62 and the cooking chamber seal 32 are made of the same material. For example, a material selected from the group consisting of silicones, rubbers, glass fibers, and silicone rubbers.

[0131] However, the second dielectric material 62 and the cooking chamber seal 32 can also consist of different materials and be selected independently of one another from the group consisting of silicones, rubbers and glass fibers as well as silicone rubbers.

[0132] In Fig. 11 is the combination cooking appliance 10 according to the invention from Fig. 2 shown in a closed state.

[0133] In the closed state, the housing-side edge region 28 of the housing 13 rests on the door-side edge region 30 of the cooking chamber door 12. This arrangement is explained below using detail C in Fig. 12 is explained in more detail, where Fig. 12 shows a plan view of the cooking chamber door 12 in the closed state viewed from the loading opening 22.

[0134] A top view of the door-side edge region 30 is visible, in which the ring mode suppressor 36 is indicated as a projection 70. The ring mode suppressor 36 and the quarter-wave trap 38 run parallel to each other and surround the loading opening 22 of the cooking chamber 20 in a closed, frame-like manner.

[0135] In addition, in the closed state, the ring mode suppressor 36 is arranged between the quarter-wave trap 38 and the cooking chamber 20.

[0136] In particular, the ring mode suppressor 36 and the quarter-wave trap 38 are arranged laterally offset from one another. More precisely, the ring mode suppressor 36 is arranged laterally offset inward toward the feed opening 22. Consequently, the quarter-wave trap 38, in the closed state, completely surrounds the projection 70 of the ring mode suppressor 36.

[0137] For a better overview of the arrangement of the housing-side and door-side edge area 28, 30 in the closed state of the combination cooking appliance 10, Fig. 13 a cross-sectional view along the section plane CC Fig. 12 shown.

[0138] In Fig. 13, the door-side edge area 30 and the housing-side edge area 28 are divided by a dashed, horizontal line that separates both areas from each other.

[0139] The area above the line is to be assigned to the housing-side edge area 28, while the area below the line belongs to the door-side edge area 30.

[0140] When closed, the door-side edge area 30 rests on the housing-side edge area 28, so that an internal cooking chamber 20, which is located in Fig. 13 on the right, upper side is located from the surroundings, which are in Fig. 13 on the left side and the lower side, is sealed.

[0141] First, the door-side edge area 30 will be discussed in more detail.

[0142] The door-side edge region 30 has a central door section 14 in which the sheet metal element 58 is arranged, which extends laterally outwards and merges into the tooth elements 50 and the inner wall 48 along its circumference, which is formed by the transition section 59.

[0143] The inner wall 48 merges into the base 44, which in turn adjoins an outer wall 46 running parallel to the inner wall 48. Thus, the outer wall 46, the inner wall 48, and the base 44 form the pot-shaped section 40. This encloses a chamber 72 open on one side, which functions as a quarter-wave trap 38. The microwaves can penetrate the chamber 72 from the open side 42.

[0144] In addition, the quarter-wave trap 38 has a geometric depth d corresponding to an electrical length of one-quarter the wavelength of the microwave radiation used in the combination cooking appliance 10. Essentially, the geometric depth d corresponds to the height of the inner wall 48 and the outer wall 46, measured from the bottom 44 to the toothed elements 50.

[0145] Opposite the bottom 44, the chamber 72 has the open side 42, into which the toothed elements 50 extend. The toothed elements 50 are located directly beneath a microwave seal in the form of the disc 16, which shields the aforementioned components from the cooking chamber 20 and the edge region 28 on the housing side, thus spatially separating them.

[0146] For this purpose, the pane 16 is fastened to an edge region of the cup-shaped section 40 via two adhesive points 71, one adhesive point being provided laterally next to the transition section 59 and the other adhesive point being provided on a plateau-shaped section 73 which runs laterally next to the outer wall 46.

[0147] Preferably, the adhesive points 71 are not formed as points, but as adhesive lines that run parallel to the cup-shaped section 40, preferably such that the quarter-lambda trap 38 is closed on both sides and surrounded by the adhesive lines 71 in a frame-like manner. In this way, contamination caused in the cooking chamber 20 can be kept away from the quarter-lambda trap 38.

[0148] The housing-side edge area 28 is described in more detail below.

[0149] The edge area 28 on the housing side has the groove 34 in which the cooking chamber seal 32 is received.

[0150] Below the cooking chamber seal 32, the ring mode suppressor 36 is provided, which consists of the first dielectric material 60 and the second dielectric material 62 (not shown here, as this is located outside the section plane CC). In the example shown in Fig. 13 further shows the variant with the third dielectric material 66, here in the form of two air inclusions, each surrounded by the first dielectric material 60.

[0151] In addition, the cooking chamber seal 32 can have an extension 74 which, when the cooking chamber door 12 is closed, projects into the cooking chamber 20 and thus effectively seals it against steam and hot air.

[0152] As in Fig. As can be clearly seen in Figure 13, the cooking chamber seal 32, when closed, seals off the loading opening 22 from the environment by sealingly resting on the pane 16. In this way, the cooking chamber climate prevailing in the cooking chamber 20 cannot escape into the environment. Consequently, a door gap 76 existing between the housing-side edge region 28 and the door-side edge region 30 is effectively sealed.

[0153] In the Fig. 14A and Fig. 14B are diagrams of 2D simulations of the electromagnetic field along the circumference of the cooking chamber door 12 of Fig. 2 shown in Fig. 14A without ring mode suppressor 36 and in Fig. 14B with ring mode suppressor 36. In both cases, the electromagnetic field is shown looking directly at the closed cooking chamber door 12. For clarity, the cooking chamber door 12 is not shown.

[0154] Dark areas indicate areas with particularly strong microwave radiation and bright areas indicate sections with particularly low microwave radiation.

[0155] In Fig. 14A, the occurrence of ring modes 78 is particularly clearly visible. These extend in the form of semicircles along the door perimeter 80 and can thus lead to increased microwave leakage in the immediate vicinity of the combination cooking appliance 10.

[0156] In comparison of the Fig. 14A and Fig. 14B it can be seen that the ring modes 78 along the door circumference 80 in Fig. 14B. In some sections along the door perimeter 80, the microwave leakage could be reduced to almost zero. In other locations, the microwave leakage in the form of ring modes 78 is still present, but significantly reduced. This is due to the presence of the ring mode suppressor 36.

[0157] Fig. 15 shows to Fig. 14A and Fig. 14B corresponding curves of the simulated 2D data.

[0158] The leakage of microwave radiation is plotted in mW / cm 2 on the y-axis versus the position along the door circumference 80 on the x-axis. Shown is a data curve 82 without ring mode suppressor (corresponds to the Fig. 14A), a data curve 84 with ring mode suppressor (corresponds to the Fig. 14B) and a limit value of 86. The limit value of 86 serves only as a reference to illustrate the difference between the two data curves.

[0159] As shown by Fig. 15, the ring mode suppressor 36 effectively reduces the intensity of the microwaves in mW / cm 2 along the entire length of the door circumference 80.

[0160] The functional principle of the combination cooking appliance 10 according to the invention in interaction with the quarter-wave trap 38 and the ring mode suppressor 36 is explained below.

[0161] A user can switch the combination cooking appliance 10 according to the invention to microwave mode or start a corresponding cooking program via a user interface 88. This can be done either via a display 90 and / or via control elements 92 in the form of keys or buttons.

[0162] The microwave operation of the combination cooking appliance 10 can be started when there is food to be cooked in the cooking chamber 20 and the cooking chamber door 12 is closed, i.e. the combination cooking appliance 10 is in a closed state.

[0163] In microwave mode, the combination cooking appliance 10, in particular the microwave source, generates microwave radiation with a specific wavelength, which impinges on the food in the cooking chamber 20 with additional energy, thereby cooking the food. Typically, the radiated microwave radiation has a frequency of 2.45 GHz (corresponding to a wavelength λ of 12 cm).

[0164] In order to prevent the microwave radiation from escaping from the cooking chamber 20 into the environment, the central door section 14 has the perforated plate 18, which serves as a central microwave seal to intercept the majority of the microwave radiation generated in the cooking chamber 20.

[0165] In order to prevent or minimize the escape of microwave radiation via the door gap 76 between the cooking chamber door 12 and the housing 13, the quarter-wave trap 38 is initially provided in the cooking chamber door 12.

[0166] The quarter-wave trap 38 is designed to intercept the incoming microwaves and prevent their propagation, for example by generating resonances.

[0167] In particular, the toothed elements 50 provided on the quarter-wave trap 38 improve the efficiency of the microwave trap. If the quarter-wave trap 38 lacks teeth, surface currents can flow unhindered in the direction of wave propagation. Interruptions caused by the toothed elements 50, however, prevent this and redirect the microwave radiation toward the interruptions.

[0168] In addition, the cooking chamber seal 32 causes a disturbance of the electromagnetic field in the form of ring modes that propagate along the circumference of the cooking chamber door 12 and that cannot be intercepted by the already existing microwave trap in the form of the quarter-wave trap 38.

[0169] For this reason, a ring mode suppressor 36 is provided below the cooking chamber seal 32 in the groove 34, which, due to its alternating structure 63, has a plurality of dielectric jumps between two different materials 60, 62 that differ in their dielectric properties.

[0170] Due to the dielectric jumps, the ring modes are suppressed at the dielectric jumps, reducing the intensity of the ring modes. This reduces the overall microwave leakage from the cooking chamber 20 into the environment.

Claims

[1] Combination cooking appliance (10) for cooking food, comprising a housing (13) surrounding a cooking chamber (20) and a cooking chamber door (12) which can assume an open and a closed state, wherein in the closed state the cooking chamber door (12) completely covers a loading opening (22) of the cooking chamber (20), wherein a groove (34) is provided in which a cooking chamber seal (32) is received in order to seal the loading opening (22) of the cooking chamber (20) in the closed state, wherein a ring mode suppressor (36) is provided which is arranged in the groove (34) below the cooking chamber seal (32), wherein the ring mode suppressor (36) has an alternating structure (63) made of at least two materials (60, 62) with different dielectric properties. [2] Combination cooking appliance (10) according to claim 1, characterized by that the alternating structure (63) and the cooking chamber seal (32) are made in one piece. [3] Combination cooking appliance (10) according to claim 1 or 2, characterized by that the ring mode suppressor (36) surrounds the feed opening (22) along an extension direction, in particular wherein the at least two dielectric materials (60, 62) are arranged alternately along the extension direction. [4] Combination cooking appliance (10) according to one of the preceding claims, characterized by that between the dielectric materials (60, 62) there is a permittivity difference in a range from 0.3 to 30, preferably from 0.5 to 5, particularly preferably from 1.0 to 2, based on the relative permittivity of the materials. [5] Combination cooking appliance (10) according to one of the preceding claims, characterized by that one dielectric material (62) is air, in particular wherein the other dielectric material (60) is selected from the group consisting of silicones, rubbers and glass fibers as well as silicone rubbers. [6] Combination cooking appliance (10) according to one of the preceding claims, characterized by that the alternating structure (63) is formed from at least three dielectric materials (60, 62, 66), of which one dielectric material (62) is air, and the other two dielectric materials (60, 66) are each selected from the group consisting of silicones, rubbers, silicone rubbers and glass fibers. [7] Combination cooking appliance (10) according to one of the preceding claims, characterized byin that a first dielectric material (60) is completely encased by a second dielectric material (62), so that a dielectric hybrid element (65) is created, wherein a plurality of dielectric hybrid elements (65) together with air as the third dielectric material (66) form the alternating structure (63), in particular wherein the plurality of dielectric hybrid elements (65) are each cuboid-shaped and form the alternating structure (63) interrupted by air slots (64). [8] Combination cooking appliance (10) according to claim 7, characterized by that the first dielectric material (60) is a silicone and the second dielectric material (62) is a rubber. [9] Combination cooking appliance (10) according to one of the preceding claims, characterized by that a lambda quarter trap (38) is provided which surrounds the feed opening (22) when closed. [10] Combination cooking appliance (10) according to claim 9, characterized bythat in the closed state the ring mode suppressor (36) is arranged between the quarter-lambda trap (38) and the cooking chamber (20), in particular wherein in the closed state the ring mode suppressor (36) and the quarter-lambda trap (38) are arranged laterally offset from one another.

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