Combination cooking appliance 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 (20) and a cooking chamber door (12), 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, wherein the groove (34) and a base section of the cooking chamber seal (32) together form a ring mode suppressor (36), since the groove (34) together with the base section of the cooking chamber seal (32) corresponds to an electrical length of the microwave radiation in the ring mode suppressor (36) that is longer than a quarter of the wavelength of the microwave radiation used in the combination cooking appliance (10).

Description

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

[0002] In professional and commercial kitchens, combination ovens are used, which are capable of cooking food in a single cooking chamber using various methods. In addition to classic cooking methods that utilize hot air and / or steam, modern combination ovens often also employ microwave radiation. Magnetrons or semiconductor components can be used as microwave sources to feed the microwaves into the cooking chamber.

[0003] It is essential to prevent microwaves, steam, and hot air from escaping the cooking chamber during the cooking process. Microwave leakage, in particular, must be avoided to minimize radiation exposure in the immediate vicinity, especially below specified limits, such as 50 mW per square centimeter at a distance of five centimeters from the cooking appliance.

[0004] Due to the aforementioned boundary conditions, combination cooking appliances are usually equipped with oven cavity seals that prevent steam and / or hot air from escaping, 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. The cooking chamber seal is a rubber seal arranged around the loading opening, which interacts with a cooking chamber door. A quarter-wave trap is provided for the microwave seal to prevent microwave radiation from escaping the cooking chamber. Both seals are spatially separated from each other to minimize any negative interaction that would result in increased microwave leakage.

[0006] Given the increasing use of such combination ovens, efforts are being made to further improve the microwave seals used in order to minimize microwave leakage from the cooking chamber without compromising the sealing effect of the oven chamber seal against hot air and steam. However, care must be taken to ensure that the different seals—the microwave seal and the oven chamber seal—do not interfere with each other during operation.

[0007] The present invention is based on the objective of providing a combination cooking appliance for cooking food that prevents the escape of the cooking chamber climate and at the same time enables an improved sealing effect against microwaves fed into the cooking chamber.

[0008] The problem is solved 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, wherein a groove is provided in which a cooking chamber seal is received to seal the loading opening of the cooking chamber in the closed state. The groove and a base section of the cooking chamber seal together form a ring mode suppressor, since the groove together with the base section of the cooking chamber seal corresponds to an electrical wavelength of the microwave radiation in the ring mode suppressor that is longer than a quarter of the wavelength of the microwave radiation used in the combination cooking appliance.

[0009] The invention is based on the understanding that a cooking chamber seal, which seals the cooking chamber against steam and hot air, can lead to a change or disturbance of the electromagnetic field during microwave operation of the combination oven. This change or disturbance can take the form of ring modes and can be understood as a periodic change or disturbance of the electromagnetic field that locally strengthens the electromagnetic field at the cooking chamber seal, which can promote and, under certain circumstances, even amplify the escape of microwave radiation. This is because the cooking chamber seal is usually located adjacent to the cooking chamber door to seal the gap between the door and the housing, allowing the ring modes to escape into the surrounding environment through the door gap without obstruction.

[0010] Ring modes are a constructive interference pattern of microwaves that form semicircular electromagnetic fields emanating from their point of origin. These fields originate at the oven door seal, which seals the loading opening, causing the ring modes to appear along the door gap between the oven door and the housing. The door gap and the oven door seal do not impede the ring modes, resulting in a leakage or escape of microwave radiation from the oven at these points.

[0011] Furthermore, it was recognized that ring modes cannot be effectively dampened by a quarter-wave trap near the oven door seal. In the worst-case scenario, a quarter-wave trap in the area of ​​the oven door seal—for example, by tuning the groove of the oven door seal to a geometric depth of approximately one-quarter of the electrical length of the wavelength used in the oven—can also generate disturbances in the form of ring modes or amplify existing ring modes. Therefore, the ring mode suppressor is not equivalent to a classic quarter-wave trap, which is standardly used for microwave door seals in well-known combination ovens.

[0012] Wavelength refers in particular to the wavelength in a vacuum (or approximately in air).

[0013] The term "electrical length" refers to the distance an electromagnetic wave travels in a propagation medium, such as a ring mode suppressor. Due to the dielectric properties of the ring mode suppressor, the electric length can differ from the length or distance the electromagnetic wave would travel in a vacuum (in the same time), which is also known as the mechanical length. In other words, the electric length, depending on the permittivity and, if applicable, the permeability of the propagation medium, is less than or at most equal to the distance in a vacuum. Mathematically, this relationship can be expressed as follows: l el = l mech ⋅ μ r ε r , where l el the electrical length, l mech the mechanical length, µ r the relative permeability number and ε r The relative permittivity corresponds to the dielectric. The product of the relative permeability µ r and the relative permittivity ε r For most materials, the product is greater than 1. In a vacuum, the product is exactly 1, whereas in air it is approximately 1.

[0014] The terms electrical length and mechanical length refer in particular to the distance from the bottom of the groove to the opening of the groove, i.e. the geometric depth of the groove.

[0015] The ring mode suppressor, i.e., the groove together with the base section of the oven seal, corresponds to the electrical length of the microwave radiation within the ring mode suppressor. This means that the electromagnetic waves of the microwave radiation, i.e., the microwaves, within the ring mode suppressor have an electrical length that is at least one-quarter of the wavelength of the microwave radiation. Depending on the material of the oven seal or the base section, the geometric depth is shorter than the electrical length. The higher the relative permeability of the oven seal material, the shorter the geometric depth of the ring mode suppressor can be while still ensuring that the electrical length of the microwave radiation within the ring mode suppressor is less than one-quarter of the wavelength of the microwave radiation (in a vacuum). This is due to the influence of permeability and permittivity, as explained above.

[0016] Therefore, the electrical length can be understood as the distance traveled in a vacuum with a shortening factor. This shortening factor arises because the electromagnetic wave (i.e., the microwave) propagates in a medium with a different permittivity (and permeability) than a vacuum, for example, in the material of the oven cavity seal. The oven cavity seal, and thus also its base section, acts as a dielectric for electromagnetic radiation entering the ring mode suppressor. This physical relationship is expressed by the shortening factor, which depends on the propagation medium and is "1" in the case of a vacuum.

[0017] As a result, the geometric depth of the groove can be correspondingly shorter, namely by the shortening factor, if a different material (propagation medium) is present in the ring mode suppressor, especially within the groove, than in the cooking chamber, e.g., the material of the cooking chamber seal.

[0018] Therefore, the following relationship generally applies: 1 4 λ ⋅ F Dichtung < d Nut , where λ corresponds to the wavelength of the microwave radiation used in the cooking chamber (in a vacuum), d groove the geometric depth of the groove and F seal the shortening factor of the cooking chamber seal arranged in the groove, where the shortening factor is given by 1 μ r ε r can be expressed.

[0019] When considering the shortening factor or the geometric depth of the groove, it is important to take into account whether the base section of the oven seal completely fills the groove or only partially. If the base section does not completely fill the groove, a material with different dielectric properties will remain in the groove. For example, a cavity may be present in the groove that has a relative permittivity (and permeability) that differs from that of the base section.

[0020] The proposed ring mode suppressor makes it easy to suppress the periodic electromagnetic field disturbances generated at the oven cavity seal in the form of ring modes, i.e., to reduce or attenuate their intensity. This minimizes the overall leakage of microwave radiation from the oven cavity. Suppression means that the intensity of the ring modes is reduced by at least half compared to the original intensity without the ring mode suppressor. Preferably, the intensity of the ring modes is reduced by at least 75%.

[0021] To ensure particularly effective suppression of ring modes, it is preferred that the electrical length of the microwave radiation in the ring mode suppressor be at least 0.1 cm greater than one-quarter of the wavelength of the microwave radiation used in the combination oven. Particularly preferred is an electrical length of at least 0.5 cm greater than one-quarter of the wavelength of the microwave radiation used in the combination oven. Most particularly preferred is an electrical length of at least 1.5 cm greater than one-quarter of the wavelength of the microwave radiation used in the combination oven.

[0022] The "base section" refers to the part of the oven seal that is inserted into the groove. This section is distinct from a section of the oven seal that protrudes from or extends beyond the groove and is compressed by the oven door when closed to achieve a seal, thus sealing the loading opening, surrounded by a door gap, from the oven environment.

[0023] Consequently, the oven cavity seal is designed to effectively seal the oven cavity against steam and hot air, which typically define the oven climate during operation of the combination oven. For this to work, the oven cavity seal must be designed to withstand the temperatures and humidity levels present in the oven cavity.

[0024] A combination cooking appliance for cooking food, as defined in the invention, is a cooking appliance used in professional or commercial kitchens. It is designed for professional use and is further equipped to cook food using a combination of different methods. These include cooking with hot air, steam, and microwave radiation.

[0025] According to a first aspect of the invention, the groove surrounds the loading opening. This allows the loading opening to be effectively sealed against steam and hot air in the cooking chamber.

[0026] In particular, the groove completely surrounds the loading opening, forming a closed, frame-like border. This enables a particularly effective seal of the loading opening.

[0027] Another aspect of the invention provides that the electrical wavelength is shorter than half the wavelength of the microwave radiation used in the combination oven. Half the wavelength is to be understood as an upper limit that must not be exceeded in order to achieve the desired suppression of ring modes. In this respect, the ring mode suppressor has a preferred range within which the electrical wavelength of the microwave radiation used in the combination oven may still be suppressed.

[0028] Depending on the material used in the ring mode suppressor, especially the material of the cooking chamber seal, the geometric length / depth of the ring mode suppressor will vary.

[0029] In any case, the ring mode suppressor has a geometric length / depth and material that ensures the electrical length of the electromagnetic radiation within the ring mode suppressor lies within the specified range, i.e., greater than a quarter of a wavelength and less than half a wavelength. For example, the electrical length can be 3 / 8 of a wavelength. Particularly effective ring mode suppression is achieved within this range.

[0030] Therefore, the following relationship applies in particular to the electrical length: 1 4 λ < d Nut ⋅ F Dichtung < 1 2 λ

[0031] To ensure particularly effective suppression of ring modes, it is preferred that the electrical length be at least 0.1 cm shorter than half the wavelength of the microwave radiation used in the combination oven. Particularly preferred is an electrical length of at least 0.5 cm shorter than half the wavelength of the microwave radiation used in the combination oven. Most particularly preferred is an electrical length of at least 1.5 cm shorter than half the wavelength of the microwave radiation used in the combination oven.

[0032] According to another aspect of the invention, the groove is provided in a housing-side edge region, so that the ring mode suppressor is arranged in the housing-side edge region. This arrangement of the ring mode suppressor is based on known groove arrangements, so that existing specifications can also be used.

[0033] According to another aspect of the invention, the base section of the oven seal completely fills the groove. In this way, the groove is completely filled with a dielectric, and particularly effective suppression of ring modes can be achieved. Furthermore, the space in the groove can be used effectively, thereby reducing material and costs.

[0034] In particular, the oven cavity seal may be a rubber seal. When closed, this effectively seals the oven cavity against hot air and steam.

[0035] Furthermore, it is an aspect of the invention that the cooking chamber seal protrudes above the groove. This enables a particularly effective seal of the cooking chamber against steam and hot air.

[0036] Another feature is a quarter-wave trap, which surrounds the loading opening when closed. A quarter-wave trap is a proven component for preventing microwave radiation from escaping the cooking chamber. The quarter-wave trap is present in addition to the ring mode suppressor.

[0037] The lambda quarter trap is particularly advantageous when positioned in a door-side edge area. Unlike a housing-side arrangement, a lambda quarter trap located in a door-side edge area is advantageously oriented to capture microwaves escaping from the cooking chamber. This position ensures that microwave radiation either does not escape from the cooking chamber or is significantly attenuated.

[0038] In principle, the lambda-quarter trap can be designed arbitrarily, as long as it has a geometric depth corresponding to an electrical length of approximately one-quarter of the wavelength of the microwave radiation used in the cooking chamber. The lambda-quarter trap can also incorporate a dielectric, resulting in a geometric depth less than one-quarter of the wavelength, while still maintaining an electrical length of one-quarter of the wavelength.

[0039] Furthermore, the quarter-wave trap also works synergistically with the ring mode suppressor, as both attenuate different types of microwave radiation. This further reduces overall microwave leakage. The ring modes are suppressed by the ring mode suppressor, and the remaining microwave radiation by the quarter-wave trap, thus effectively preventing or reducing microwave leakage.

[0040] In another aspect of the invention, the ring mode suppressor is arranged between the quarter-wave trap and the cooking chamber when the appliance is 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 exiting the cooking chamber, while 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 surrounding environment.

[0041] In principle, any arrangement of ring mode suppressor and lambda quarter trap is possible in the combination cooking appliance, as long as the above-mentioned boundary conditions are met.

[0042] For example, the ring mode suppressor and the lambda quarter trap can both be located together in the oven door or together in the edge area of ​​the oven housing along the loading opening.

[0043] However, it is also conceivable that one of the two components is the oven door and the other component is the oven housing.

[0044] Particularly advantageous are the lambda quarter trap in the oven door and the ring mode suppressor on the oven housing along the loading opening. Thus, when the combination oven is closed, the ring mode suppressor is positioned between the lambda quarter trap and the oven chamber, as described above.

[0045] Particularly advantageous in the closed state is the laterally offset arrangement of the ring mode suppressor and the lambda quarter trap. This arrangement enables particularly effective attenuation of microwave radiation.

[0046] According to a further aspect of the invention, the lambda-quarter trap has a pot-shaped section formed in a door-side edge region. In the closed state, the lambda-quarter trap has an open side pointing towards the housing-side edge region.

[0047] The pot-shaped section refers to the part of the quarter-wave trap that causes the microwaves to resonate. Therefore, this section can have a geometric depth corresponding to one-quarter of the wavelength of the microwave radiation used in the cooking appliance, provided no dielectric is used. This allows for the simple implementation of a quarter-wave trap.

[0048] If a dielectric is provided in the pot-shaped section of the quarter-wave trap, the geometric length of the pot-shaped section can deviate from one-quarter of the wavelength of the microwave radiation, even if the electrical length of the pot-shaped section corresponds to one-quarter of the wavelength of the microwave radiation. The shortening factor then also applies accordingly.

[0049] According to a further embodiment of the invention, the lambda quarter trap is provided with a ring formed from several tooth elements separated by slots, which extend laterally outwards from the feed opening, so that the tooth elements are opposite the open side of the pot-shaped section of the lambda quarter trap.

[0050] Further features and advantages of the invention will become apparent from the following description and from the accompanying drawings, to which reference is made. The drawings show: Figure 1 an isometric representation of a combination cooking appliance from the prior art; Figure 2 an isometric representation of a combination cooking appliance according to the invention with a housing-side ring mode suppressor; Figure 3 an isometric representation of a combination cooking appliance according to the invention with a door-side ring mode suppressor; Figure 4 a detailed representation of the combination cooking appliance according to the invention made of Figure 2 in an open state; Figure 5 a detailed representation of the combination cooking appliance according to the invention made of Figure 2 in a closed state; Figure 6 a schematic top view of detail A from Figure 5 ; Figure 7 a schematic cross-sectional view along the cutting plane AA from Figure 6 ; Figure 8 a schematic cross-sectional view of a ring mode suppressor made of Fig. 2 according to an embodiment of the invention; Figures 9A and 9B Each diagram is from 2D simulations of the electromagnetic field along the circumference of the oven door. Figure 2 , in Fig. 9A without ring mode suppressors and in Fig. 9B with ring mode suppressor; and Figure 10 a diagram with data curves from the 2D simulations from the Figures 9A and 9B .

[0051] Figure 1 shows a state-of-the-art combination cooking appliance 10.

[0052] 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.

[0053] The oven 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 sheet 18. The construction of the door section 14 will be described later with reference to Fig. 4 explained in detail.

[0054] The housing 13 encloses a cooking chamber 20, which is accessible from outside the combination cooking appliance 10 through a loading opening 22 in the housing 13. Food can be placed in or removed from the cooking chamber 20 via the loading opening 22.

[0055] The loading opening 22 is completely covered by the cooking chamber door 12 when it is closed.

[0056] 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.

[0057] The outer casing 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 circumference of the loading opening 22 is essentially completely surrounded by the housing-side edge region 28.

[0058] The oven door 12 has a door-side edge area 30 corresponding to the housing-side edge area 28, wherein in the closed state of the oven door 12 the housing-side edge area 28 and the door-side edge area 30 lie on top of each other and seal the oven room 20 from the environment.

[0059] 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).

[0060] Typically, the cooking chamber climate in cooking chamber 20 is regulated via the hot air source and / or the steam generator, 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 monitor the cooking process or to measure cooking parameters, for example, to determine the load in the cooking chamber, a process generally referred to as "sensing."

[0061] Basically, the combination oven 10 can cook food either using only microwave radiation or only the ambient temperature of the cooking chamber. Of course, both methods can also be used in combination, i.e., simultaneously or in parallel.

[0062] In Figure 2 A combination cooking appliance 10 according to the invention is shown. This also features the combination cooking appliance described in Figure 1 The characteristics already described are present. Therefore, for an explanation of these characteristics, please refer to the description above.

[0063] Compared to the one in Figure 1 The combination cooking appliance 10 shown, which is from the state of the art, exhibits the following features: Figure 2 The combination cooking appliance 10 shown according to the invention 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.

[0064] The groove 34 with the cooking chamber seal 32 included therein is provided in the housing-side edge area 28 and completely surrounds the loading opening 22.

[0065] The groove 34 and the cooking chamber seal 32 together form a ring modifier 36. Details of the ring modifier 36 are given below with reference to Fig. 8 explained in detail.

[0066] While the cooking chamber seal 32 is designed to seal the cooking chamber 20 against steam and heat, the ring mode suppressor 36 is designed 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.

[0067] Additionally, a quarter-wave lambda trap 38 is provided on the oven door 12, extending along the door-side edge 30. When the combination oven 10 is closed, the quarter-wave lambda trap 38 extends along the door-side edge 30 and completely surrounds the loading opening 22 in a frame-like manner. The quarter-wave lambda trap 38 serves to prevent microwave radiation generated during microwave operation from escaping from the oven chamber 20 into the surrounding environment, thus reducing microwave leakage.

[0068] According to an alternative embodiment, the position of the ring mode suppressor 36 and that of the lambda quarter-trap 38 can be reversed. In other words, the lambda quarter-trap 38 can be located in the housing-side edge region 28, and the ring mode suppressor 36, together with the oven cavity seal 32 and the groove 34, can be located in the door-side edge region 30. This is illustrated by example in Figure 3 shown.

[0069] Preferably, the ring mode suppressor 36 is provided together with the groove 34 and the cooking chamber seal 32 on the housing-side edge area 28, and the lambda quarter trap 38 on the door-side edge area 30, as well as in Figure 2 has been shown and explained accordingly.

[0070] The following section describes the design of the lambda quarter trap 38 according to the embodiment in Figure 2 described in more detail.

[0071] A detailed description of the construction of the lambda quarter trap 38 in the oven door 12 is in the Figures 4 and 7 recognizable, which will be referenced below.

[0072] In the illustrated embodiment, the lambda quarter trap 38 is designed as a pot-shaped section 40 which, when the combination cooking appliance 10 is closed, extends in a frame-like manner around the loading opening 22. The pot-shaped section 40 has an open side 42 which is oriented towards the loading opening 22 of the cooking chamber 20.

[0073] Opposite the open side 42, a base 44 of the pot-shaped section 40 is provided, to which an outer wall 46 and an inner wall 48 are attached, both of which are aligned parallel to each other. The terms "outer" and "inner" refer here to the respective position in relation to the geometric center of the oven door 12.

[0074] In the embodiment according to the Figures 4 and 7 The pot-shaped section 40 specifically has a U-shaped cross-section defined by the outer wall 46, the inner wall 48, and the base 44. The U-shaped cross-section is in Fig. 7 to recognize and will be explained in detail below.

[0075] Basically, the pot-shaped section 40 represents the actual lambda quarter trap 38, which prevents the microwaves fed into the cooking chamber 20 from escaping from the cooking chamber 20.

[0076] Furthermore, the lambda-quarter trap 38 has several tooth elements 50, which are spaced apart from each other 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 project into or are associated with the open side 42 of the pot-shaped section 40, which in Fig. 7is also shown.

[0077] The tooth elements 50 are arranged along the pot-shaped section 40, forming a tooth ring 54. More precisely, the tooth ring 54 is designed as a comb-like structure that, when the combination cooking appliance 10 is closed, surrounds the loading opening 22 in a frame-like manner. Each of the individual tooth elements 50 has one side facing the bottom 44 of the pot-shaped section 40.

[0078] In addition, the toothed ring 54 extends, when viewed from above, along a rectangular base shape, which is rounded at each of the four corners.

[0079] The toothed ring 54 surrounds, as can be seen in particular from Figure 7It is further evident that the sheet metal element 58 comprises the perimeter of a flat sheet metal element 58, in particular the perforated sheet 18, wherein the sheet metal element 58 completely covers the central door section 14. In particular, the toothed ring 54 is provided at a formed end of the sheet metal element 58.

[0080] Therefore, the several tooth elements 50 extend laterally outwards from the circumference of the sheet metal element 58.

[0081] The pot-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.

[0082] The inner wall 48 and the sheet metal element 58 meet in a common transition section 59. Specifically, the transition section 59 is designed as a common edge.

[0083] In particular, the pot-shaped section 40 attaches to the sheet metal element 58 in the area where the toothed ring 54 is provided on the sheet metal element 58.

[0084] Consequently, the sheet metal element 58, the inner wall 48 and the tooth elements 50 meet at the transition section 59.

[0085] Preferably, the sheet metal element 58, the pot-shaped section 40 and the tooth elements 50 are made together in one piece.

[0086] The aforementioned elements are particularly preferably made of a metallic material or an alloy.

[0087] It is also conceivable that the sheet metal element 58, the pot-shaped section 40 and the tooth elements 50 are welded together in the transition section 59.

[0088] The perforated sheet metal 18 is provided in the central door section 14, which is covered by the sheet metal element 58.

[0089] Preferably, the perforated sheet 18 is formed in one piece together with the sheet metal element 58, and the perforated sheet 18 represents a central section of the sheet metal element 58, such that the circumference of the perforated sheet 18 is surrounded by the sheet metal element 58.

[0090] Alternatively, the sheet metal element 58 can have a central recess in which the perforated sheet 18 is inserted and welded to the sheet metal element 58 at the edge.

[0091] The perforated plate 18 serves primarily as an additional microwave seal and prevents the microwave radiation fed into the cooking chamber 20 from escaping into the surrounding area through the central door section 14. At the same time, this ensures that the cooking chamber 20 can be viewed when the cooking chamber door 14 is closed.

[0092] Furthermore, when closed, the lambda quarter 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 located in the area of ​​the central door section 14 and is formed by the disc 16.

[0093] In particular, the disk 16 can be attached to the lambda quarter trap 38 via at least one adhesive point.

[0094] In Figure 5 The combination cooking appliance 10 according to the invention is made of Figure 2 shown in a closed state.

[0095] In the closed state, the housing-side edge region 28 of the housing 13 rests on the door-side edge region 30 of the oven door 12. This arrangement is shown below with reference to detail A in Figure 6 explained in more detail, whereby Figure 6 a top view of the cooking chamber door 12 in the closed state as seen from the loading opening 22.

[0096] A top view of the door-side edge area 30 is visible, in which the ring mode suppressor 36 is indicated as a projection 60. The ring mode suppressor 36 and the lambda quarter trap 38 run parallel to each other and surround the loading opening 22 of the cooking chamber 20 in a closed, frame-like manner.

[0097] Furthermore, in the closed state, the ring mode suppressor 36 is arranged between the lambda quarter trap 38 and the cooking chamber 20.

[0098] In particular, the ring mode suppressor 36 and the lambda-quarter trap 38 are arranged laterally offset from each other. More precisely, the ring mode suppressor 36 is arranged laterally offset inwards towards the feed opening 22. Consequently, in the closed state, the lambda-quarter trap 38 completely surrounds the projection 60 of the ring mode suppressor 36.

[0099] For a better overview of the arrangement of the housing-side and door-side edge areas 28, 30 in the closed state of the combination oven 10, is shown in Figure 7 a cross-sectional view along the cutting plane AA from Figure 6 shown.

[0100] In Figure 7 The door-side edge area 30 and the housing-side edge area 28 are divided by a dashed, horizontal line that separates the two areas from each other.

[0101] 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.

[0102] 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 Figure 7 on the upper right side of the surroundings, which are in Figure 7It is located on the left side and the bottom side, and is sealed.

[0103] First, the door-side edge area 30 will be discussed in more detail.

[0104] The door-side edge area 30 has a central door section 14 in which the sheet metal element 58 is arranged, which extends laterally outwards and along its perimeter, which is formed by the transition section 59, transitions into the tooth elements 50 and the inner wall 48.

[0105] The inner wall 48 transitions into the base 44, which in turn connects to 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 62 open on one side, which functions as a quarter-wave trap 38. Microwaves can penetrate the chamber 62 from the open side 42.

[0106] Furthermore, the lambda-quarter trap 38 has a geometric depth dλ corresponding to an electrical length of one-quarter of the wavelength of the microwave radiation used in the combination oven 10. Essentially, the geometric depth dλ corresponds to the height of the inner wall 48 and the outer wall 46, measured from the base 44 to the tooth elements 50.

[0107] Opposite the base 44, the chamber 62 has the open side 42 into which the tooth elements 50 extend. The tooth elements 50 are located directly below a microwave seal in the form of the disc 16, which shields and thus spatially separates the aforementioned components from the cooking chamber 20 and the housing-side edge area 28.

[0108] For this purpose, the disc 16 is attached to an edge area of ​​the pot-shaped section 40 via two adhesive points 64, one adhesive point being located laterally next to the transition section 59 and the other adhesive point being located on a plateau-shaped section 66 that runs laterally next to the outer wall 46.

[0109] Preferably, the adhesive points 64 are not formed as points, but as adhesive lines 64 that run parallel to the pot-shaped section 40, preferably such that the lambda quarter trap 38 is closed on both sides and surrounded by the adhesive lines 64 in a frame-like manner. In this way, soiling caused in the cooking chamber can be kept away from the lambda quarter trap 38.

[0110] The housing-side edge area 28 is described below according to the Fig. 2 , 4 , 7 and 8 described in more detail.

[0111] The housing-side edge area 28 has the groove 34 in which the cooking chamber seal 32 is received.

[0112] In the closed state, the groove 34 has a groove opening 68 pointing towards the door-side edge area 30, as can be seen in particular from Fig. 7 becomes clear.

[0113] From the groove opening 68, two groove walls 70, 72 extend, which terminate in a groove base 74 arranged opposite the groove opening 68. The groove base 74 limits the depth of the groove 34 on the housing side.

[0114] The groove walls 70, 72 together with the groove base 74 form a receptacle 78 in which the cooking chamber seal 32 is received.

[0115] In particular, according to the embodiment in Figure 7 provided that the groove 34 has an undercut 76 pointing towards the bottom of the groove 74, so that the cooking chamber seal 32 can be securely held in the groove 34.

[0116] The oven cavity seal 32 comprises a base section 80 and a head section 82, which are manufactured together as a single piece. In particular, the oven cavity seal 32 can be a rubber seal.

[0117] The base section 80 is characterized by the fact that it is essentially completely recessed in the receptacle 78 of the groove 34. Accordingly, the base section 80 extends between the groove bottom 74 and the groove opening 68. In particular, the base section 80 can extend continuously from the groove bottom 74 to the groove opening 68, so that the base section 80 of the cooking chamber seal 32 completely fills the receptacle 78 of the groove 34.

[0118] It is also conceivable that the base section 80 only partially fills the groove 34. For example, the base section 80 may be designed so that it does not extend completely to the bottom of the groove 74. Consequently, a cavity 84 remains between the base section 80 and the bottom of the groove 74, which is filled with air, as shown in Figure 8 shown.

[0119] The groove 34, together with the base section 80 of the cooking chamber seal 32, forms the ring mode suppressor 36. The groove 34, together with the base section 80, ensures that the electromagnetic wave has an electrical length λ that is longer than one quarter of the wavelength λ of the microwave radiation used in the combination oven 10.

[0120] Furthermore, the electrical length λ is preferably shorter than half the wavelength of the microwave radiation used in the combination cooking appliance 10.

[0121] The electrical length λ corresponds here to the geometric depth d of the groove 34, taking into account a shortening factor based on the material of the base section 80, in particular describing the dielectric properties of the material of the base section 80. The base section 80 acts as a dielectric for the incoming electromagnetic radiation in the microwave range and thus shortens the wavelength of the electromagnetic radiation in the propagation medium compared to the wavelength in a vacuum. In other words, the shortening factor describes the effect that the wavelength in a propagation medium other than a vacuum is shorter than in a vacuum, namely by the shortening factor.

[0122] The shortening factor depends not only on the dielectric constant of the base section 80, but also on the extent to which the base section 80 extends into the recess 78. If the recess 78 of the groove 34 is completely filled by the base section 80, then the incident wavelength perceives the groove 34 as a homogeneous dielectric.

[0123] If a cavity 84 remains in the groove 34, as in Figure 8 As shown, because, for example, the base section 80 does not extend to the bottom of the groove 74, the arriving wavelength perceives the groove 34 as an inhomogeneous dielectric consisting of the base section 80 and the cavity 84. This results in a different shortening factor. Consequently, the geometric depth d of the base of the base section 80, the electrical length λ, and the shortening factor can mutually influence or depend on each other. Fig. 7 is d Nut equal to d Basis , whereas in Fig. 8Due to the existing cavity, dgroove is not equal to dbase. In the latter case, dgroove is greater than dbase.

[0124] The geometric depth d of the groove 34 is defined as the distance from the center point 86 of the groove opening 68 to the groove bottom 74. The center point 86 of the groove opening 68 lies in a common plane with the two groove edges 88 of the groove 34, which is in Figure 8 is represented as a dashed line.

[0125] Consequently, the geometric depth d base of the base section 80 is the distance from the center point 86 of the groove opening 68 to the end 90 of the base section 80 facing the groove bottom 74.

[0126] In the area of ​​the groove opening 68, the head section 82 joins the base section 80 and protrudes beyond the groove opening 68. The cooking chamber seal 32 also protrudes beyond the groove 34.

[0127] When the oven door 12 is closed, the head section 82 rests against the glass 16, so that the oven cavity 20 and the loading opening 22 are spatially separated by a door gap 92. In other words, the oven cavity seal 32, in particular the head section 82, seals the oven cavity 20 from the surroundings.

[0128] Additionally, the head section 82 can transition into an extension 94 that extends towards the cooking chamber 20. When the cooking chamber door 12 is closed, the extension 94 is located inside the cooking chamber 20 and thus provides a particularly good seal between the cooking chamber 20 and the door gap 92.

[0129] In the Figures 9A and 9B Each diagram is a 2D simulation of the electromagnetic field along the circumference of the oven door 12. Figure 2 shown, in Fig. 9A without ring mode suppressor 36 and in Fig. 9Bwith ring mode suppressor 36. In both cases, the electromagnetic field is shown in the direction of a frontal view of the oven door 12 in the closed state. For clarity, the oven door 12 is not shown.

[0130] Dark areas indicate regions with particularly strong microwave radiation, while light areas indicate sections with particularly low microwave radiation.

[0131] In Figure 9A The occurrence of ring modes 96 is particularly noticeable. These extend in the form of semicircles along the door circumference 98 and thus lead to increased microwave leakage in the immediate vicinity of the combination oven 10.

[0132] In comparison of the Figures 9A and 9B It is evident that the ring modes 96 along the door circumference 98 in Fig. 9BThe microwave leakage was effectively suppressed. In some sections along the door circumference 98, the microwave leakage could be reduced to almost zero. In other places, the microwave leakage in the form of ring modes 96 is still present, but significantly reduced. This is due to the presence of the ring mode suppressor 36.

[0133] Figure 10 shows two to Figure 9A and Figure 9B Corresponding curves of the simulated 2D data.

[0134] The microwave leakage in mW / cm² is plotted on the y-axis against the position along the door circumference 98 on the x-axis. A data curve 100 without a ring mode suppressor (corresponding to the Figure 9A ), a data curve 102 with ring mode suppressor (corresponds to the Figure 9B ) and a limit value of 104. The limit value of 104 serves only as a reference to illustrate the difference between the two data curves.

[0135] As demonstrated by Figure 10As can be clearly seen, the ring mode suppressor 36 effectively reduces the intensity of the microwaves in mW / cm 2< along the entire length of the door circumference 98.

[0136] The following explains the operating principle of the combination cooking device 10 according to the invention in conjunction with the lambda quarter trap 38 and the ring mode suppressor 36.

[0137] A user can switch the combination cooking appliance 10 according to the invention to microwave operation or start a corresponding cooking program via a user interface 106. This can be done either via a display 108 and / or via control elements 110 in the form of buttons or knobs.

[0138] The microwave operation of the combination oven 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., when the combination oven 10 is in a closed state.

[0139] In microwave operation, the combination oven 10, in particular the microwave source, generates microwave radiation with a specific wavelength λ, which imparts (additional) energy to the food in the cooking chamber 20, thus cooking the food. The emitted microwave radiation typically has a frequency of 2.45 GHz (corresponding to a wavelength λ of 12 cm).

[0140] To prevent 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 rays generated in the cooking chamber 20.

[0141] To prevent or minimize the escape of microwave radiation through the door gap 92 between the oven door 12 and the housing 13, the lambda quarter trap 38 is first provided in the oven door 12.

[0142] The lambda quarter trap 38 is designed to intercept the incoming microwaves and prevent their propagation, for example by generating resonances.

[0143] In particular, the toothed elements 50 provided on the lambda-quarter trap 38 improve the efficiency of the microwave trap. If the lambda-quarter trap 38 lacks the teeth, surface currents can flow unhindered in the direction of wave propagation. Interruptions caused by the toothed elements 50, however, prevent this and deflect the microwave radiation in the direction of the interruptions.

[0144] In addition, the oven cavity seal 32 together with the groove 34 into which the oven cavity seal 32 is inserted causes a disturbance of the electromagnetic field in the form of ring modes, which propagate along the door circumference of the oven cavity door 12 and which cannot be intercepted by the existing microwave trap in the form of the lambda quarter trap 38.

[0145] For this reason, the ring mode suppressor 36 is provided in the form of the groove 34 and the base section 80 of the cooking chamber seal 32, which together ensure that the microwave propagating through the ring mode suppressor 36 has an electrical length λ that is longer than a quarter of the wavelength of the microwave radiation used in the combination cooking appliance 10.

[0146] Due to its electrical length λ, which is longer than a quarter of the microwave wavelength, the ring mode suppressor 36 disrupts the ring modes, thereby reducing their intensity. This reduces the overall microwave leakage from the cooking chamber 20 into the environment.

Claims

1. A 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 the groove (34) and a base section (80) of the cooking chamber seal (32) together form a ring mode suppressor (36), since the groove (34) together with the base section (80) of the cooking chamber seal (32) corresponds to an electrical length of the microwave radiation in the ring mode suppressor (36) which is longer than a quarter of the wavelength of the microwave radiation used in the combination cooking appliance (10). Microwave radiation is.

2. Combination cooking appliance (10) according to claim 1, characterized in thatthe groove (34) surrounds the loading opening (22).

3. Combination cooking appliance (10) according to claim 1 or 2, characterized in that the electrical length is shorter than half the wavelength of the microwave radiation used in the combination cooking appliance (10).

4. Combination cooking appliance (10) according to one of the preceding claims, characterized in that the groove (34) is provided in a housing-side edge region (28), so that the ring mode suppressor (36) is arranged in the housing-side edge region (28).

5. Combination cooking appliance (10) according to one of the preceding claims, characterized in that the base section (80) of the cooking chamber seal (32) completely fills the groove (34), in particular wherein the cooking chamber seal (32) is a rubber seal.

6. Combination cooking appliance (10) according to one of the preceding claims, characterized in that the cooking chamber seal (32) protrudes beyond the groove (34).

7. Combination cooking appliance (10) according to one of the preceding claims, characterized in that a quarter-lambda trap (38) is provided which, in the closed state, surrounds the loading opening (22), in particular wherein the quarter-lambda trap (38) is provided in a door-side edge region (30).

8. Combination cooking appliance (10) according to claim 7, characterized in that in the closed state, the ring mode suppressor (36) is arranged between the quarter-lambda trap (38) and the cooking chamber (20) and / or that in the closed state, the ring mode suppressor (36) and the quarter-lambda trap (38) are arranged laterally offset from one another.

9. Combination cooking appliance (10) according to claim 7 or 8, characterized in thatthe quarter-wave trap (38) has a pot-shaped section (40) which is formed in a door-side edge region (30), wherein the quarter-wave trap (38) in the closed state has an open side (42) pointing in the direction of the housing-side edge region (28).

10. Combination cooking appliance (10) according to claim 9, characterized in that the quarter-lambda trap (38) has a ring (54) with a plurality of tooth elements (50) separated by slots (52) which extend laterally outwards from the feed opening (22) so that the tooth elements (50) are opposite the open side (42) of the cup-shaped section (40) of the quarter-lambda trap (38).

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