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Publication numberUS3654417 A
Publication typeGrant
Publication dateApr 4, 1972
Filing dateOct 30, 1970
Priority dateOct 30, 1970
Publication numberUS 3654417 A, US 3654417A, US-A-3654417, US3654417 A, US3654417A
InventorsVernon E Cassibo, Wallace R Javes
Original AssigneeLitton Precision Prod Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Microwave oven including air flow system
US 3654417 A
Abstract
An improved air flow system for a microwave oven which includes blower means for providing a heated air flow, a portion of this heated air flow is directed into the cavity of a microwave oven by duct means. Filter means is located on the air exhaust end of the cavity, such filter means having a reservoir to collect condensation so that a large volume of condensation-laden air is not exhausted from the microwave oven at any one time.
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Description  (OCR text may contain errors)

[151 3,654,417 [4 1 Apr.4,1972

United States Patent Javes et al.

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ts, lnc., Beverly [73] Assignee: Litton Precision Produc Attorney-Franklin D. Jankosky, Walter R. Thiel, Alfred B.

Hills, Calif. Levine and Alan C. Rose [22] Filed: Oct. 30, 1970 voir to collect condensation so that a large volume of condensation-laden air is not exhausted from the microwave oven at any one time.

[ 56] References Cited UNITED STATES PATENTS 3,430,023 2/1969 Tingley...............................2l9/l0.55 3Claims,6l)rawingFigures PATENTEUAPR 4 1972 SHEET 1 OF 2 WALL-ACE R JAVES VERNON E. CASS/50 ATTORNEY PATENTEDAPR 4 I972 3,554,417

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ryzs 29 N WALLACE R. JAVES vm/von/ 5. 6455/50 ATTORNEY mvsmons imxhu 1 MICROWAVE OVEN INCLUDING AIR FLOW SYSTEM FIELD OF THE INVENTION This invention relates to air flow within a microwave oven and more particularly to a novel air flow system within a microwave oven which employs an intrusion-proof window as part of the door that forms a wall of the cavity of the microwave oven.

DESCRIPTION OF THE PRIOR ART It is well known that microwave ovens operating usually at the frequency of 2.45 gigaHertz may be utilized for heating foodstuff. The foodstuff may be placed in a heating cavity of a microwave oven and exposed to microwave energy supplied by a suitable source, e.g., a megnetron. Molecular agitation within the foodstuff resulting from its exposure to microwave energy provides frictional heat to cook the foodstuff in a relatively short period of time as compared to conventional gas or electric heating, In the earlier microwave oven technology, solid door construction was utilized to form one of the walls of the heating cavity. For example, G. B. Long et al., in US. Pat. No. 2,748,239 issued May 29, 1956 taught a microwave oven having solid door construction on the side of the oven and a small glass window on the top of the oven. Heated air was directed under the window and then directed into the cavity. The heated air was then vented out of the cavity through an exhaust located in proximity to the glass window.

In later years, the microwave ovens incorporated an RF screen, which is a sheet of metal having a plurality of holes located therein, which, in conjunction with the inner surface of the door formed the wall of the cavity to prevent microwave energy from escaping through the door, but permitted one to view any foodstuff that was being heated within the cavity. However, it is presently felt that it would possibly be dangerous to employ a door having an RF screen that would allow an individual to insert a metal object into the holds of the RF screen. Therefore, RF screens are now employed that include sheets of glass, or plastic material on both sides of the RF screen. One of the problems incurred because of the use of this type of intrusion-proof window is that condensation builds up within the cavity, particularly on the inner surface of the intrusion-proof window because the cavity is relatively airtight.

Accordingly, it is an object of the present invention to provide an improved air flow system for a microwave oven employing an intrusion-proof type window.

It is a further object of the present invention to provide an improved air flow system for a microwave oven to ensure purging of condensation-laden air from the cavity of the microwave oven.

It is a still further object of the present invention to provide an improved air flow system for a microwave oven which ensures that relatively heavy volume condensation-laden air is not expelled from the microwave oven at any one time.

SUMMARY OF THE INVENTION In accordance with the objects set forth above, the present invention provides an improved air flow system for a microwave oven which includes a blower means for providing a heated air flow, a portion of this heated air flow is directed into the cavity of a microwave oven by duct means. Filter means is located on the air exhaust end of the cavity, such filter means having a reservoir to collect condensation so that a large volume of condensation-laden air is not exhausted from the microwave oven at any one time.

BRIEF DESCRIPTION OF THE DRAWINGS Additional objects, advantages, and characteristic features of the present invention will become readily apparent from the following detailed description of the preferred embodiments of the invention when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a microwave oven, with portions of the housing and the door cut away to expose various components located therein, in accordance with the present invention;

FIG. 2 is a plan view of a microwave oven taken along lines 2-2 of FIG. 1, in accordance with the present invention;

FIG. 3 is an elevational view of the inner side of a filter of the microwave oven, in accordance with the present invention;

FIG. 4 is an elevational view of the rear end of the filter of FIG. 3, in accordance with the present invention;

FIG. 5 is an elevational view of the outer side of the filter of FIG. 3, in accordance with the present invention; and

FIG. 6 is an elevational view of the inner side of the door of the microwave oven, in accordance with the present invention. 1

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 and 2, there is respectively shown a perspective view of a microwave oven 10 with various portions of the housing and a door 12 cut away to expose components located herein, and a plan view of the microwave oven 10 taken along lines 2-2 of FIG. 1, in accordance with the present invention. The door 12 is cut away to illustrate a cavity 11 and other components which will be described in detail later in the specification. The door 12 includes an intrusion-proof window 13, which is comprised of two panes of glass having a conventional RF screen located between the panes of glass. As is well known, the RF screen is a sheet of metal having a plurality of holes located therein which in conjunction with the inner surface of the door 12 forms a wall of the cavity 11 to prevent microwave energy from escaping from that portion of the microwave oven 10, but permits one to view any foodstuff that is being heated within the cavity 11.

Referring now to the components that are part of or are located within the housing of the microwave oven 10, the various components incorporated within the air flow system of the present invention will be described. An air input opening 14, comprised of a multitude of small openings over an area approximately 40 square inches, is located on the bottom housing of the microwave oven 10. Located in proximity of or above the air input opening 14 is a pair of transformers, namely, a filament transformer 15 and a high voltage transformer 16. Located directly above the air input opening 14 are a motor-driven blower 17, a conventional magnetron 18 having horizontal cooling fins, as shown, and a duct 21. Further illustrated is a waveguide 19 and a stirrer housing 20. As is well known in the art, the microwave energy from the magnetron 18 travels within the waveguide 19 to the stirrer housing 20, which includes a conventional stirrer, or metallic fan, to stir the microwave energy in order to establish a multiplicity of modes of microwave energy within the cavity 11. Since the transmission of the microwave energy from the magnetron 18 to the cavity 11 per se is well known to those skilled in the art, such transmission need not be further described herein.

The duct 21 may be constructed of electrical fish paper which is a fire-retardant and electrical insulating material, and is divided into two compartments by means of a divider 22 of like material. Thus, air flowing over the cooling fins of the magnetron 18 will be divided into two parts, so that a portion of the air will be exhausted from the microwave oven 10 through the opening 22 and the rest of the air will flow into the cavity 11 through an opening 23. The opening 23 consists of a multiple number of holes drilled in the illustrated right side metallic wall of the cavity 11 and the opening 24 consists of a multiple number of holes that are drilled in the rear housing of the microwave oven 10. On the upper front part of the left side metallic wall of the cavity 11 there is shown a cavity air exhaust opening 25 which allows air within the cavity 11 to be exhausted therefrom. On the other end of the cavity air exhaust opening 25 there is shown a filter 26 which permits exhausted air from the cavity 11 to flow out of the microwave oven by means of an air exhaust opening 27 which is the approximate height of the filter 26. The filter 26 may be of natural polystyrine material and may be constructed by a vacuum formed process. The filter 26 has respective openings 28 and 30 which allow the above-described air flow through the filter 26 to be accomplished.

During the operation of the microwave oven 10, outside air, illustrated by the arrows designated A, is drawn into the microwave oven 10 by means of the blower motor 17, which may be of the conventional squirrel cage type. The arrows designated B illustrate the air fiow established around the filament transformer and the high voltage transformer 16, and

other smaller electronic components and connection means,

not shown. The transformers 15 and 16 and the other electronic components dissipate heat during the operation of the microwave oven 10. Thus, the temperature of the air designated by the arrows B is at a higher temperature than the air designated by the arrows A. The blower l7 draws in such heated air and exhausts it over the cooling fins of the magnetron 18 to cool the magnetron 18, thus accomplishing further heating of the air. The divider 22 of the duct 21 ensures that approximately three-fifths of the air is vented out of the microwave oven 10 through the air exhaust opening 24 and the other two-fifths is vented into the cavity 11 through the air input opening 23. The above-described air flow is illustrated by the arrows designated C, while the air flow within the cavity 11 is illustrated by the arrows designated D. The latter air flow picks up any condensation that forms on the walls of the cavity 11, particularly any condensation on the intrusionproof window 13. Condensation forms on the walls of the cavity 11 because such walls, including the window 13, are cooler than the rising temperature of the foodstuff being heated. This condensation-laden air then travels out of the cavity 11 by means of the air exhaust opening 25 and the opening 28 of the filter 26. The arrow designated E illustrates the air flow through the filter 26 that is then exhausted out of the microwave oven 10 by means of the air exhaust opening 27.

Referring now to FIGS. 3, 4 and 5, there are shown respective elevational views of the inner side, the rear end, and the outer side of the filter 26, in accordance with the present invention. The opening 28 has a rubber grommet 29 which is located flush against the outer wall of the left side of the housing in order that all of the condensation-laden air travels into the filter 26 rather than to other parts of the microwave oven 10 so that no moisture collects within portions of the microwave oven 10 containing electronic components, e.g., directly below the filter 26. Further illustrated is a condensation reservoir 31 of the filter 26 that is formed by a raised lip portion 32 of approximately one-fourth inch in height to establish the reservoir 31 that runs the approximate length of the filter 26. Thus, a majority of the condensation existing in the air flow defined by the arrow designated E is retained in the reservoir 31 and is not directly exhausted to the outside of the microwave oven 10. The water collected in the reservoir 31 will evaporate into the air when the microwaveoven 10 is not in operation. Since the microwave oven 10 illustrated is of a portable consumer type that may be moved anywhere within a household, it is important that the condensation-laden air is not directly exhausted from the microwave oven 10 because of the accompanying puddles of water that could form anywhere in the home.

Referring now to FIG. 6, there is shown an elevational view of the inner side of the door 12 of the microwave oven 10. A rubber gasket 33 is shown located approximately around the entire perimeter of the door 12, except in the area of the latch 35. While rubber gaskets similar to the type shown had been used in the early years of microwave oven manufacture to prevent the escape of microwave energy through the perimeter of the door of a microwave oven, since such rubber gaskets tended to burn due to arcing of microwave energy, manufacturers have generally employed microwave energy chokes, either metallic channels, or channels filled with a dielectric such as, poypropolyne to attenuate such microwave energy. The choke illustrates such attenuation means and 1t attenuates the majority of the microwave energy that might otherwise escape through the perimeter of the door 12. While the rubber gasket 33 will attenuate the second harmonic of the microwave, if the rubber gasket 33 is flush with the front housing of the microwave oven 10, it further serves the purpose of retaining the condensation-laden air within the cavity 11 rather than forming water which drops down the front of the microwave oven 10.

Thus, although the present invention has been shown and described with reference to particular embodiments, for example, filter means having a reservoir located in the bottom thereof, nevertheless, various changes and modifications obvious to a person skilled in the art to which the invention pertains, for example, filter means having absorptive means located therein, are deemed to lie within the spirit, scope and contemplation of the invention as set forth in the appended claims.

What is claimed is:

1. An air flow system for exhausting condensation from a portable microwave oven comprising:

a cooking cavity having six electrically conductive bounded walls, one of said walls being the exterior surface of a partially transparent door that provides access to said cooking cavity, said cooking cavity including air flow means for directing air over said interior surface of said door, said air flow means including a first plurality of relatively small sized diameter openings for allowing heated air to flow into said cooking cavity and a second plurality of relatively small sized diameter openings located in close proximity to said interior surface of said door for exhausting condensation-laden air from said cooking cavity;

electrical means, including a magnetron and a waveguide coupled between said magnetron and said cooking cavity, for supplying electromagnetic wave energy to said cooking cavity;

blower means located on the one side of said magnetron for directing air to said magnetron for cooking said magnetron and for providing a heated air flow;

duct means located on the opposite side of said magnetron for directing a first portion of said heated air flow out of said portable microwave oven and a second portion of said heated air fiow into said cooking cavity via said first plurality of openings of said air flow means; and

filter means located outside of said cooking cavity and abutting said second plurality of openings of said air flow means for receiving said exhausted condensation-laden air from said cooking cavity, said filter means including a reservoir for extracting and retaining moisture within said exhausted condensation-laden air prior to exhausting the air within said filter means from said microwave oven.

2. An air flow system as recited in claim 1 wherein said filter means has an opening located in proximity of said second plurality of openings of said air flow means, said filter means further including a rubber grommet around the perimeter of said opening of said filter means for ensuring that all of said condensation-laden air is directed to said filter means.

3. An air flow system as recited in claim 2 wherein said reservoir of said filter means is the approximate length of said filter means and has a height of approximately one-fourth inch.

' zg gg I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N 3 ,654, l7 Dated April LL, 1972 Inventor s Wallace R. Javes; Vernon E. Cassibo It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 16: megnetr'on" should be --magnetron- Col. 2, line 23: herein" should be --therein- Col. line i- H cooking" should be --cooling-- Signed and sealed this 28th day of November 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR

ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents P041050 7 UNITED STATES PATENT OFFEQE CERTIFICATE OF CORREC'HN Patent No. 3 7 Dat d April l 1972 Inventor s Wallace R. Javes; Vernon E. Cassibo It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 16 "megnetron" should be --magnetron- Col. 2-, line 23: "herein" should be "therein-- Col. l, line ML: cooking" should be --cooling- Signed and sealed this 28th day of November 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer o Commissioner of Patents

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3410116 *Oct 24, 1966Nov 12, 1968Melvin L. LevinsonMicrowave and ultrasonic apparatus
US3430023 *Sep 11, 1967Feb 25, 1969Roper Corp Geo DDoor construction and ventilating system for microwave oven
US3440385 *Oct 13, 1966Apr 22, 1969Microtherm LtdElectronic ovens
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3780251 *Jan 3, 1972Dec 18, 1973Micromatic Systems LtdMicrowave heating apparatus
US3818171 *May 26, 1972Jun 18, 1974Sage LaboratoriesMicrowave cooking apparatus
US3867605 *Aug 6, 1973Feb 18, 1975Welbuilt CorpMicrowave oven
US3909574 *Mar 28, 1974Sep 30, 1975Kreis AgMicrowave tunnel-ovens
US4123643 *May 31, 1977Oct 31, 1978Whirlpool CorporationAir circulation system for microwave oven
US4262183 *Sep 24, 1979Apr 14, 1981General Electric CompanyCombination microwave/forced convection oven
US4297558 *Apr 25, 1980Oct 27, 1981Rinnai Kabushiki KaishaComposite cooking device
US4313043 *Aug 21, 1978Jan 26, 1982General Electric CompanyCombination microwave oven and exhaust vent and installation mounting method therefor
US4327274 *Apr 23, 1980Apr 27, 1982General Electric CompanyVentilation system for combination microwave oven and exhaust vent
US4332992 *Dec 19, 1979Jun 1, 1982Amana Refrigeration, Inc.Air flow system for combination microwave and convection oven
US4454404 *Nov 24, 1981Jun 12, 1984Tokyo Shibaura Denki Kabushiki KaishaHigh frequency heating apparatus with selectable steam generating means
US4565669 *Apr 21, 1983Jan 21, 1986Cem CorporationMicrowave ashing apparatus
US4618756 *Jul 8, 1985Oct 21, 1986Whirlpool CorporationAir circulation system for microwave oven
US4812617 *Dec 20, 1982Mar 14, 1989Sharp Kabushiki KaishaCooling system for cooling electrical parts for microwave oven
US6592448 *Mar 7, 2000Jul 15, 2003Contrapposto, Inc.Computers with power exhaust systems
US6750434 *Dec 20, 2002Jun 15, 2004Samsung Electronics Co., Ltd.Microwave oven
US6909079Nov 17, 2003Jun 21, 2005Lg Electronics Inc.Microwave oven having an internal components cooling structure
US7166824 *Jan 8, 2003Jan 23, 2007Matsushita Electric Industrial Co., Ltd.High-frequency heating apparatus and control method thereof
US7825358Aug 31, 2007Nov 2, 2010Lg Electronics Inc.Cooking apparatus having rear component space
US7910866Aug 31, 2007Mar 22, 2011Lg Electronics Inc.Cooking apparatus having multiple cooling flow paths
US8035065Aug 31, 2007Oct 11, 2011Lg Electronics Inc.Cooking apparatus having a door with a built in control panel
US8058594Aug 31, 2007Nov 15, 2011Lg Electronics Inc.Door for a cooking apparatus
US8143560Sep 12, 2007Mar 27, 2012Lg Electronics Inc.Cooking apparatus
US8164036Aug 31, 2007Apr 24, 2012Lg Electronics Inc.Cooking apparatus
US8168928Sep 12, 2007May 1, 2012Lg Electronics Inc.Cooking apparatus
US8304702Aug 26, 2010Nov 6, 2012Lg Electronics Inc.Cooking apparatus
US8375849Aug 31, 2010Feb 19, 2013Manitowoc Foodservice Companies, LlcMethod and apparatus for an air inlet in a cooking device
US8586900Aug 31, 2007Nov 19, 2013Lg Electronics Inc.Cooking apparatus having cooling flow path
US8680449Aug 26, 2010Mar 25, 2014Lg Electronics Inc.Cooking apparatus
US8941041Aug 31, 2007Jan 27, 2015Lg Electronics Inc.Cooking apparatus having a cooling system
US8975562 *May 3, 2011Mar 10, 2015General Electric CompanyOver the range microwave safety door
US20090206076 *Feb 13, 2009Aug 20, 2009Seiichi HiranoCooking device
US20120279957 *May 3, 2011Nov 8, 2012General Electric CompanyOver the range microwave safety door
US20130160410 *Dec 19, 2012Jun 27, 2013Samsung Electronics Co., Ltd.Air filter mounting/demounting apparatus for over-the-range microwave oven
CN100334392C *Nov 14, 2002Aug 29, 2007三星电子株式会社微波炉
DE4231897A1 *Sep 20, 1992Mar 24, 1994Kraftwerk Schlammtechnologie UCombined microwave and convective heating process - uses microwave prodn. waste heat, esp. for drying bulk material, e.g. wood chips and waste water sludge
EP0000955A1 *Aug 30, 1978Mar 7, 1979Litton Systems, Inc.Method for browning foods in a microwave oven
EP0000956A1 *Aug 30, 1978Mar 7, 1979Litton Systems, Inc.Method of cooking juiced foods in a microwave oven
EP0000958A1 *Aug 30, 1978Mar 7, 1979Litton Systems, Inc.Method for cooking non-liquid food in a microwave oven
EP0000959A1 *Aug 30, 1978Mar 7, 1979Litton Systems, Inc.Method of cooking thin meat bodies in a microwave oven
EP0001396A1 *Aug 30, 1978Apr 18, 1979Litton Systems, Inc.Method of cooking meat in a microwave oven
EP0069105A1 *Jun 18, 1982Jan 5, 1983De Belgische Staat L'Etat Belge représenté par le Secrétaire général des Services de ProgrammationIndustrial modular microwave oven
EP0584934A1 *Jul 21, 1993Mar 2, 1994Kabushiki Kaisha ToshibaHeating apparatus
EP0866643A2 *Sep 19, 1997Sep 23, 1998Samsung Electronics Co., Ltd.Microwave oven
EP1424876A2 *Nov 18, 2003Jun 2, 2004LG Electronics, Inc.Microwave oven
EP1682825A1 *Oct 15, 2004Jul 26, 2006LG Electronics, Inc.Air flow passage of microwave oven
EP2064493A1 *Dec 7, 2006Jun 3, 2009LG Electronics, Inc.Cooking apparatus
WO1991011084A1 *Jan 5, 1991Jul 25, 1991Reinhard SchulzeMicrowave chamber and associated magnetron unit
WO2009108035A1 *Feb 28, 2008Sep 3, 2009Quinasa S.A. De C.V.Methods for obtaining preservative-free stable avocado pulp powders and products compacted from same
Classifications
U.S. Classification219/757
International ClassificationH05B6/80
Cooperative ClassificationH05B6/642
European ClassificationH05B6/64E