DOMESTIC MICROWAVE APPLIANCE WITH MICROWAVE TRAP AND METHOD FOR THE PRODUCTION THEREOF

Abstract

A household microwave appliance includes a microwave treatment chamber having a loading opening, a door for closing the loading opening of the microwave treatment chamber, and a microwave trap configured to prevent microwaves escaping when the door is closed. The microwave trap is a bent sheet-metal component with a main bending edge, which is adjoined by a row of teeth at a distance. The microwave trap includes a row of bending slots in the main bending edge, with at least one of the bending slot being interrupted by a web to define slot sections.

Claims

1-15. (canceled)

16. A household microwave appliance, comprising: a microwave treatment chamber having a loading opening; a door for closing the loading opening of the microwave treatment chamber; and a microwave trap configured to prevent microwaves escaping when the door is closed, said microwave trap being a bent sheet-metal component with a main bending edge, which is adjoined by a row of teeth at a distance, said microwave trap including a row of bending slots in the main bending edge, with at least one of the bending slot being interrupted by at least one web to define slot sections.

17. The household microwave appliance of claim 16, wherein the bending slots are arranged in parallel to the teeth.

18. The household microwave appliance of claim 16, wherein the slot sections have a length which is not greater than 1 cm.

19. The household microwave appliance of claim 16, wherein the slot sections have a length which is not greater than 0.9 cm.

20. The household microwave appliance of claim 16, wherein the slot sections have a length which is not greater than 0.8 cm.

21. The household microwave appliance of claim 16, wherein the at least one of the bending slots is interrupted by precisely one said web.

22. The household microwave appliance of claim 16, wherein the at least one web traverses the at least one of the bending slots centrally.

23. The household microwave appliance of claim 16, wherein the at least one web traverses the at least one of the bending slots eccentrically.

24. The household microwave appliance of claim 16, wherein the at least one of the bending slots is interrupted by multiple of said web.

25. The household microwave appliance of claim 24, wherein the multiple webs traverse the at least one of the bending slots equidistantly.

26. The household microwave appliance of claim 24, wherein the multiple webs traverse the at least one of the bending slots non-equidistantly.

27. The household microwave appliance of claim 16, wherein the at least one web has a length of at least approximately 2 mm.

28. The household microwave appliance of claim 16, wherein one of the bending slots is arranged completely inside a longitudinal section of a corresponding one of the teeth which is arranged in parallel to the one of the bending slots.

29. A method for producing a microwave trap of a household microwave appliance from a sheet-metal component, said method comprising: forming bending slots in the sheet-metal component along an intended main bending edge at a distance from a row of teeth arranged on a remote edge, with each of the bending slots being interrupted by a web to define slot sections; and bending the sheet-metal component at the intended main bending edge.

30. The method of claim 29, further comprising reshaping the sheet-metal component by deep drawing.

31. The method of claim 29, wherein the slot sections have a length along the main bending edge of not more than 0.9 cm.

32. The method of claim 29, wherein the slot sections have a length along the main bending edge of not more than 0.8 cm.

33. The method of claim 29, wherein the bending slots are formed in the sheet-metal component in parallel to the teeth.

Description

[0050] The properties, features and advantages described above of this invention and the way in which these are achieved will become clearer and more comprehensible in connection with the following schematic description of an exemplary embodiment, which is explained in greater detail in connection with the drawings.

[0051] FIG. 1 shows as a sectional view seen from the side a sketch of a basic structure of a household microwave appliance in the form of a microwave cooking appliance with a microwave trap;

[0052] FIG. 2 shows in a plan view a detail from a sheet-metal component, from which a conventional microwave trap can be created by bending;

[0053] FIG. 3 shows in an oblique view a sectional detail from the finished conventional microwave trap;

[0054] FIG. 4A to 4D show as sectional views seen from the side in sketch form the sheet-metal component from FIG. 3 in different sections of a bending process for the production of the microwave trap from FIG. 3;

[0055] FIG. 5 shows in a plan view a detail from a sheet-metal component, from which an inventive microwave trap in accordance with a first exemplary embodiment can be created by bending;

[0056] FIGS. 6A and 6B show as sectional views seen from the side in sketch form the sheet-metal component from FIG. 5 in different sections of a bending process for the production of the microwave trap in accordance with the first exemplary embodiment from FIG. 7;

[0057] FIG. 7 shows in an oblique view a sectional detail from the finished microwave trap in accordance with the first exemplary embodiment;

[0058] FIG. 8 shows in a plan view a detail from a sheet-metal component, from which an inventive microwave trap in accordance with a second exemplary embodiment can be created by bending;

[0059] FIG. 9 shows in an oblique view a sectional detail from the finished bent microwave trap in accordance with the second exemplary embodiment; and

[0060] FIG. 10 shows a plot of microwave attenuation S21 in dB against a microwave frequency in GHz, plotted for microwave traps with septal teeth without bending slots, with a conventional bending slot and the bending slots in accordance with the first and second forms of embodiment.

[0061] FIG. 5 shows in a plan view in a representation analogous to FIG. 2 a detail from a sheet-metal component 3, which can be bent to form a microwave trap 2. This microwave trap 2 can be installed in a microwave cooking appliance 1 instead of the conventional microwave trap 106. The microwave cooking appliance 1 can in other respects be structured analogously to the conventional microwave cooking appliance 101.

[0062] The sheet-metal component 3 differs from the sheet-metal component 110 in that the bending slots 4 are interrupted by a web 5 (which can also be referred to as a “connection web”) or a web 5 traverses the respective bending slot 4. As a result, two slot sections 6a and 6b are created at the respective bending slot 4. The bending slot 4 can advantageously have one or more of the following properties: [0063] the bending slot 4 is situated at the height of or in the longitudinal section of the tooth 113; [0064] the length L1 of the bending slot 4 lies in a range L2±10%, in particular between [0.9.Math.L2; L2]; [0065] the bending slot 4 is arranged symmetrically (i.e. not offset in respect of the longitudinal extension x) to the tooth 113; [0066] the length of the bending slot 4 lies in a range [1.5 cm; 3 cm]; [0067] a length L4 of the web 5 lies in a range [1 mm; 3 mm], in particular is 2 mm; [0068] the web 5 traverses the bending slots 4 centrally, as a result of which equal lengths L1-1 and L1-2 of the two slot sections 6a or 6b are produced; [0069] the lengths L1-1 and L1-2 of the two slot sections 6a or 6b are in each case not more than 0.9 cm, in particular not more than approx. 0.8 cm.

[0070] In particular, all bending slots 4 can have the same properties. Alternatively, one, more or all bending slots 4 can have at least one property differing from these properties. For example, the web 5 can eccentrically traverse one, more or all bending slots 4, in which case the two slot sections 6a and 6b have different lengths L1-1 or L1-2.

[0071] The length L3 of the recess 112 can advantageously lie between 0.4.Math.L2 and 0.6.Math.L2, in particular can be approx. 0.5.Math.L2.

[0072] FIG. 6A shows in a representation analogous to FIG. 4A the metal sheet 3 as a sectional view through a tooth 113 prior to the remote-side bending to form the microwave trap 2. Here the sheet-metal component 3 is deep-drawn prior to the start of the bending process, as a result of which a deep-drawn step TS running in the longitudinal direction x is created at the edge region R. The deep drawing does not require any bending slots.

[0073] Starting from the state shown in FIG. 6A the sheet-metal component 3 can be bent analogously to FIG. 4A to FIG. 4D, as a result of which the microwave trap 2 shown in FIG. 6B is produced. The section between the two bending lines B1 and B2 is in particular transient to the plane of the sheet-metal component 3 behind the step TS. In other words, the section extends between the second bending line B2 and the main bending edge B3 over the same height as the step TS.

[0074] FIG. 7 shows, in a representation analogous to FIG. 5, a detail from the microwave trap 2.

[0075] FIG. 8 shows, in a representation analogous to FIG. 5, a detail from a sheet-metal component 9, which can be bent to form a microwave trap 8. This microwave trap 8 can likewise be installed in a microwave cooking appliance 7 instead of the conventional microwave trap 106. The microwave cooking appliance 7 can in other respects be structured analogously to the conventional microwave cooking appliance 101 or the microwave cooking appliance 1.

[0076] The sheet-metal component 9 differs from the sheet-metal component 110 in that the bending slots 10 are interrupted by two webs 5 or two webs 5 traverse the bending slot 4 at a distance from one another. As a result, three slot sections 11a, 11b and 11c are created. The bending slot 10 can advantageously have one or more of the following properties: [0077] the bending slot 10 is situated at the height of or in the longitudinal section of the tooth 113; [0078] the length L1 of the bending slot 10 lies in a range L2±10%, in particular between [0.9.Math.L2; L2]; [0079] the bending slot 10 is arranged symmetrically (i.e. not offset in respect of the longitudinal extension x) to the tooth 113; [0080] the length of the bending slot 10 lies in a range [1.5 cm; 3 cm]; [0081] a length L4 of the respective webs 5 lies in a range [1 mm; 3 mm], in particular is 2 mm; [0082] the webs 5 traverse the respective bending slot 10 equidistantly; [0083] the lengths L1-1 and L1-2 of the two slot sections 6a or 6b are in each case not more than 0.9 cm, in particular not more than approx. 0.8 cm.

[0084] In particular, all bending slots 10 can have the same properties. Alternatively, one, more or all bending slots 10 can have at least one property differing from these properties. For example, the webs 5 can eccentrically traverse one, more or all bending slots 10 non-equidistantly, in which case at least two of the three slot sections 11a, 11b and 11c have different lengths L1-1, L1-2 or L1-3.

[0085] The length L3 of the recess 112 can advantageously lie between 0.4.Math.L2 and 0.6.Math.L2, in particular can be approx. 0.5.Math.L2.

[0086] FIG. 9 shows a detail from the microwave trap 8 in a representation analogous to FIG. 7.

[0087] FIG. 10 shows a plot of a microwave attenuation S21, which sets out the ratio of the field strengths of the microwave field in and outside the cooking chamber 102, in dB against a microwave frequency in GHz, plotted for microwave traps 106, 4 and 8 with septal teeth 113 without bending slots (continuously drawn curve K1), with a conventional bending slot 114 (continuously drawn curve K2) and the bending slots 4 (dotted curve K3) and 10 (dashed curve K4) in accordance with the first or second inventive form of embodiment.

[0088] In simulations of the microwave trap hitherto, the bending slots are not simulated at the same time, but are left out of consideration. In the associated attenuation curve K1 the attenuation minimum lies at approx. 2.48 GHz.

[0089] If conventional bending slots 114 are now taken into consideration in the simulation, the attenuation minimum shifts by more than 100 MHz, as shown in the attenuation curve K2.

[0090] A deviation such as this produces a markedly increased leakage rate, if a microwave frequency in the microwave treatment chamber of approx. 2.48 GHz is assumed. The leakage rate is then typically increased by approximately a factor of 10.

[0091] By introducing just one web 5 into the bending slots 4 the attenuation minimum is closely approximated to the situation without bending slots, in attenuation curve K3 for example it is approx. 2.46 GHz. For the example shown, this frequency corresponds to a desired target operating frequency. As a result, the leakage rate can be effectively reduced.

[0092] By introducing two webs 5 into the bending slots 10 the attenuation minimum is approximated even further to the situation without bending slots (see attenuation curve K4).

[0093] The above simulations are performed for an operating range of the microwave frequency by way of example in a frequency range typical thereof of approx. 2.46 GHz±20 MHz. The specifically desired frequency range is a function of specific properties of the cooking appliance and of the microwave generator. Analogous results have also been obtained for an operating range between 902 MHz and 928 MHz.

[0094] The present invention is not of course restricted to the exemplary embodiment shown.

[0095] Thus the teeth can also be shaped differently, for example L-shaped or straight in cross-section. Furthermore, when at a right angle to the bending lines they can have a non-rectangular shape. e.g. wave-like or conical, etc.

[0096] In general “a”. “an”, etc. can be understood as a singular or a plural, in particular in the sense of “at least one” or “one or more”, etc., so long as this is not explicitly excluded, e.g. by the expression “precisely one”, etc.

[0097] A figure quoted can also include precisely the number stated as well as a customary tolerance range, so long as this is not explicitly excluded.

LIST OF REFERENCE CHARACTERS

[0098] 1 Microwave cooking appliance [0099] 2 Microwave trap [0100] 3 Sheet-metal component [0101] 4 Bending slot/microwave trap [0102] 5 Web [0103] 6a First slot section [0104] 6b Second slot section [0105] 7 Microwave cooking appliance [0106] 8 Microwave trap [0107] 9 Sheet-metal component [0108] 10 Bending slot [0109] 11a First slot section [0110] 11b Second slot section [0111] 11c Third slot section [0112] 101 Microwave cooking appliance [0113] 102 Cooking chamber [0114] 103 Loading opening [0115] 104 Door [0116] 105 Flange [0117] 106 Microwave trap [0118] 107 Cover [0119] 108 Microwave generator [0120] 109 Rotary antenna [0121] 110 Sheet-metal component [0122] 111 Free edge [0123] 112 Recess [0124] 113 Tooth [0125] 114 Bending slot [0126] f Microwave frequency [0127] B1-B3 Bending lines [0128] K1-K4 Attenuation curves [0129] L1 Length of the bending slot 4 [0130] L1-1 Length of the first slot section [0131] L1-2 Length of the second slot section [0132] L1-3 Length of the third slot section [0133] L2 Length of the tooth [0134] L3 Length of the recess [0135] L4 Length of the web [0136] R Edge region [0137] S21 Microwave transmission [0138] TS Deep-drawn step [0139] x Longitudinal extension