MICROWAVE OVEN PROVIDING A TORTUOUS PATH DOOR SEAL FIELD OF THE DISCLOSURE

[0001] The field of this disclosure includes microwave systems and more particularly microwave ovens.

BACKGROUND

A microwave oven heats materials by passing microwave radiation through it. Microwaves are a form of non-ionizing electromagnetic radiation with a frequency higher than ordinary radio waves but lower than infrared light. Microwave ovens use frequencies in one of the industrial, scientific, or medical bands, which are reserved for this use, so they do not interfere with other wireless services. Consumer ovens usually use 2.45 gigahertz (GHz)— a wavelength of 12.2 centimeters (4.80 in) while large industrial/commercial ovens often use 915 megahertz (MHz) 32.8 centimeters (12.9 in). Water, fat, and other substances in foods absorb energy from microwaves in a process called dielectric heating. Many molecules (such as those of water) are electric dipoles, meaning that they have a partial positive charge at one end and a partial negative charge at the opposite end, and therefore rotate as they try to align themselves with the alternating electric field of microwaves. Rotating molecules hit other molecules and put them into motion, thus dispersing energy. This energy, when dispersed as molecular vibration in solids and liquids, that is, as both the potential energy and kinetic energy of atoms, is heat., It is the lag in response of the polar water molecule to the impending electromagnetic wave that causes dielectric loss referred to as dipole interaction.

The cooking chamber in a microwave oven is similar to a Faraday cage but there is no continuous metal-to-metal contact around the rim of the door of the chamber thereby preventing microwave transmission out of the oven. The oven door usually has a window for easy viewing, with a layer of conductive mesh some distance from the outer panel to maintain shielding. Because the size of the perforations in the mesh is much less than the microwaves' wavelength microwave radiation cannot pass through the door, while visible light does. Microwave oven door construction is designed to limit the amount of radiation that is able to pass out of the oven. Patent US 8455803 to Denzer et al relates to a wave choke device for an oven door of a microwave oven. The wave choke device includes a front shielding comprising at least one conductive material and a wave trap forming a channel with one at least partially open side, which wave trap is arranged on at least one outer portion of the front shielding and comprises at least one conductive material. The wave choke device includes a plurality of lamellae arranged uniformly in the at least partially open side of the wave trap, which lamellae comprises at least one conductive material. The wave choke device comprises one single piece made of a perforated material, which includes at least the front shielding and the wave trap. Patent US 7053348 discloses a microwave oven capable of reducing electromagnetic noises in the 2.45 GHz band which are generated during operation of the oven. The oven, includes a main body having a heating chamber and a door attached. A ferrite sheet is disposed to cover a gap formed between the microwave oven main body and the door so as to reduce the electric waves leaking through a choke groove formed in a door pane. A punched metal plate is disposed on an outer side of a rear window film and a wire mesh sheet is disposed on an inner side of a front window glass which shields the electric waves leaking through the window of the door, and the shielded electric waves are directed via a copper tape, an aluminum tape and an EMI gasket to a door case. Ferrite sheets reduce electric waves leaking through the gap of the door. Patent US 5981927 to Osepchuk et al discloses a microwave oven with a cabinet and a door attached to the cabinet. The door has a screen, an absorbing film, and a frame. The screen reflects microwave energy away from the absorbing film, and has a plurality of screen lines and a plurality of screen openings. The absorbing film absorbs microwave energy passing through the screen. The frame supports the screen and the absorbing film in order to form a window through the door and to maintain leakage of microwave energy through the door from the chamber below a predetermined level. The frame supports the screen and the absorbing film so that the screen and the absorbing film are separated by a distance which is as least as great as the screen period, and the screen and the absorbing film are electrically attached to the frame.

It is clear from the foregoing that an objective of microwave oven construction is to attenuate energy leakage from the cooking chamber. This objective is to reduce harm to nearby humans although microwave in such cooking devices is non-ionizing so presents a relatively small risk. A further objective of attenuating microwave energy loss is to reduce interference with other wireless devices especially those operating at low power levels.

SUMMARY

[0002] In view of the foregoing an objective of the presently described and illustrated microwave oven is to maximize the attenuation of energy leakage from the cooking chamber. A further objective is to provide an improved cooling system for operating components. A still further objective is to provide an improved window for viewing the interior of the cooking chamber.

[0003] According to an embodiment, a tortuous path is provided in the door sealing structure to enable attenuation of microwave energy. This is accomplished by using a ridge within a groove approach and with multiple ridge/groove sets placed in series, energy leakage can be reduced to any degree desired limited only by the surface areas of the front chamber frame and the corresponding surface area of the oven door.

[0004] Improved cooling is achieved by using frontal air intake and conducting this intake air around both sides of the operating equipment wherein cooling fins or other cooling features may be used to draw operating heat out of the central portions of the machine and to discharge heated air rearward.

[0005] Several improvements to the structure arrangement of a door window are incorporated into the oven to improve visibility and to reduce energy leakage at the same time.

[0006] These and other aspects of embodiments herein described will be better appreciated when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

[0007] In this document, the terms "a" or "an" are used, as is common in patent documents, to include one or more than one. Furthermore, the term "or" is used to refer to a nonexclusive "or," such that "A or B" includes "A but not B," "B but not A," and "A and B," unless otherwise indicated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Embodiments of the described apparatus are illustrated only as examples in the figures of the accompanying drawing sheets wherein the same reference numeral refers to the same element as it may appear in multiple drawing sheets.

[0009] Figure 1 is a left-front side perspective view of an apparatus as disclosed herein;

[0010] Figure 2 is a frontal perspective view thereof;

[0011] Figure 3 is a right-front side perspective view thereof;

[0012] Figure 4 is a section view taken along cutting plane line 4-4 in Fig. 1;

[0013] Figure 5 is an enlarged portion taken from Fig. 4 at line 5, and

[0014] Figure 6 is a separated view of a door of the apparatus showing interior elements.

DETAILED DESCRIPTION

[0015] A microwave oven 10 is disclosed and illustrated in Figs. 1-6. In an embodiment, as shown in Fig. 2, a cabinet 20 has a frame 30 secured at the front thereof and surrounding an opening 40 into cabinet 20. A door 50 engaged with cabinet 20 in a hinged or other relationship, is in a position for sealing opening 40 as shown in Figs. 1 and 3. A control panel 21 is located below door 50 and an air inlet screen 22 is located below control panel 21. As shown in Fig. 1, duct 23A on the lower left side of cabinet 20 conducts outside cooling air from screen 22 into the operating components of oven 10 within its interior. This cooling air is discharged at the rear of cabinet 20 at duct 24. Element 52 in Fig. 1 is a door latch. Cooling air from screen 22 also moves through duct 23B on the right side of cabinet 20 and is also exhausted via rear duct 24.

[0016] In an embodiment, door 50 has a primary structural member 60, as shown in Fig. 6, which provides rigidity. As shown in Fig. 2 the inner surface of door 50 may have protruding ridges 70 forming a rectangular race track shaped arrangement and likewise frame 30 may have corresponding grooves 80 as best shown in Fig. 4. [0017] In an embodiment, and referring now to Fig. 4, a first ridge 70 may be extensive outwardly from door 50. A first groove 80 may be extensive inwardly into frame 30. Likewise, ridges 70 and grooves 80 may reverse their positions. First ridge 70 and first groove 80 may be extensive around opening 40 as shown in Fig. 2 and may be continuous or not. A seal 90 as for instance, shown in Fig. 5 may be positioned within each of grooves 80 in a position wherein door 50 is spaced apart from frame 30 when ridge 70 is inserted into groove 80 when door 50 is closed toward frame 30.

[0018] In an embodiment multiple ridges 70 and grooves 80 may be used in order to create an extensive torturous path to microwave energy seeking to escape from cabinet 20.

[0019] In an embodiment (not illustrated in the figures), it should be clear that a ridges 70 may be formed on both door 50 and frame 30 with corresponding opposing grooves 80 on both door 50 and frame 30.

[0020] In an embodiment, seals 90 may be positioned within grooves 80 as shown in Fig. 5.

[0021] In an embodiment, a plurality of components may be mounted within a window frame 65 of structural member 60 as shown in Fig. 6. Such components may include: a door film 100, a screen 110, a foam gasket 120, a peripheral strip 130, and a window 140. Door film 100 may be of Teflon® or similar material, screen 110 may be of aluminum and may be plated with magnesium or other material and may be perforated for passing energy in the visible spectrum while blocking microwave energy.

[0022] In an embodiment, foam gasket 120 may be of a flame retarding material 122 attached to a layer of aluminum metallized polyurethane 124 or other material and may have an adhesive agent 126 to assure permanent attachment in grooves 80.

[0023] In an embodiment, window 140 may include a copper nickel mesh 142 and may be metallized and sandwiched between glass plates 144.

[0024] In an embodiment, peripheral strips 130 may be of aluminum. [0025] In an embodiment, a ridged polymeric partition 150 may be of polyester positioned for compressing the plurality of components into window frame 65 and may have a window partition 155 secured thereto for use in establishing compression. [0026] In an embodiment, a door front panel 160 may be fastened to primary rigid structure 60 for securing the plurality of components in place within window frame 65 while permitting visual access to the interior of oven 10.

[0027] In the foregoing description, embodiments are described as a plurality of individual parts, and methods as a plurality of individual steps and this is solely for the sake of illustration. Accordingly, it is contemplated that some additional parts or steps may be added, some parts or steps may be changed or omitted, and the order of the parts or steps may be re-arranged, while maintaining the sense and understanding of the apparatus and methods as claimed.