EP0131324A2 - Procédé pour la fabrication des portes pour fourneaux qui combinent le chauffage à micro-ondes et à résistance électrique - Google Patents

Procédé pour la fabrication des portes pour fourneaux qui combinent le chauffage à micro-ondes et à résistance électrique Download PDF

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Publication number
EP0131324A2
EP0131324A2 EP84200916A EP84200916A EP0131324A2 EP 0131324 A2 EP0131324 A2 EP 0131324A2 EP 84200916 A EP84200916 A EP 84200916A EP 84200916 A EP84200916 A EP 84200916A EP 0131324 A2 EP0131324 A2 EP 0131324A2
Authority
EP
European Patent Office
Prior art keywords
door
side wall
outer backing
frame
glass pane
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP84200916A
Other languages
German (de)
English (en)
Other versions
EP0131324A3 (fr
Inventor
Mario Fioroli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
IRE Industrie Riunite Eurodomestici SpA
Koninklijke Philips NV
Original Assignee
IRE Industrie Riunite Eurodomestici SpA
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by IRE Industrie Riunite Eurodomestici SpA, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical IRE Industrie Riunite Eurodomestici SpA
Publication of EP0131324A2 publication Critical patent/EP0131324A2/fr
Publication of EP0131324A3 publication Critical patent/EP0131324A3/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/76—Prevention of microwave leakage, e.g. door sealings
    • H05B6/763—Microwave radiation seals for doors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C15/00—Details
    • F24C15/02—Doors specially adapted for stoves or ranges
    • F24C15/04—Doors specially adapted for stoves or ranges with transparent panels

Definitions

  • This invention relates to a method of manufacturing doors for domestic ovens which cook or heat food by using a combination of microwave and conventional electrical resistance heating elements.
  • the electrical resistance heating elements may also be used for the thermal destruction at about 500 0 e (pyrolysis) of the food residues present in the chamber of the oven, which is then referred to as a "pyrolytic oven”.
  • the cooking or heating of foods in microwave ovens is well known.
  • the temperature attained in the cooking chamber of such ovens generally does not exceed 100 0 C so that their doors, either by choice of materials or by arrangement and construction of component parts, are designed only to withstand such a temperature and prevent microwave leakage. Doors intended for this known type of oven using only microwave energy are described for example in U.S. Patents Nos. 3,767,884 and 4,146,768.
  • the first of these patents describes a door construction comprising a perforated shield of large thickness which is provided with a side wall having a plurality of transverse slots, and gaskets of thermoplastic material such as polystyrene or polypropylene which are unable to withstand temperatures of 250°C or more, as exist in ovens which use the combined microwave and electrical resistance heating.
  • perforated shields of large thickness exert considerable stresses on the gaskets and on the casing and undergo substantial deformation, which can cause fracture of the glass panes provided in the door to allow visual observation of the cooking chamber.
  • the door construction according to the second of these patents although comprising a flat perforated shield of small thickness, which may be even less than 1 mm, also comprises two glass panes which adhere to the opposite sides of the perforated shield. There are therefore no air chambers, which are known to constitute the best barrier to heat transmission.
  • This door construction further comprises an outer frame moulded in one piece of aluminium or zinc which makes a direct contact with an inner frame shaped as a metal profile. A path of high thermal conductivity is therefore created and, as a consequence, the outer frame can reach a temperature which is dangerous to the user and not very different from that inside the oven cooking chamber. This known door construction is therefore unsuitable for use in an oven operating at high temperatures.
  • 4,206,338 describes a self-contained window unit comprising three glass panes and a microwave shield which is adapted to be assembled into the door of microwave ovens, which also carprise resistance heaters for the automatic cleaning of the cooking chamber by pyrolysis, and which are therefore able to operate at high temperature.
  • the patent in question does not describe how the rest of the door is constructed in order to prevent the electromagnetic waves dispersing to the outside along the door contour .
  • Known industrial embodiments of this patent clearly show that the door has to be even more complicated and has to have a considerable thickness, to an extent which reduces the useful capacity of the oven when the oven has the overall dimensions (length and depth not exceeding 60 cm) provided under ISO standards.
  • An object of the present invention is to provide a relatively simple and inexpensive method of manufacturing a door for combined microwave and resistance heating which will form an effective barrier to both microwaves and heat.
  • a method of manufacturing a door for a domestic oven of the type combining microwave and electrical resistance heating the door including at least one pair of glass panes in spaced parallel relation, an electrically conductive perforated metal shield, and door frame means for supporting the glass panes and the shield and for providing a microwave energy seal along the periphery of the door, characterized in that the method comprises the following steps:
  • the door 4 comprises an inner annular backing door 5 which is pressed from sheet steel and comprises along its outer periphery a continuous side wall 6 having a plurality of transverse parallel slots 7.
  • the inner backing door 5 defines a central aperture by means of an edge 8 formed by an inclined portion and a terminal portion parallel to the flat surface forming the major part of this inner backing door 5.
  • An annular stiffening frame 11 is also pressed from sheet steel and welded along its two longitudinal flanges 9, 10 to the front side of the inner backing door 5.
  • the stiffening frame 11 comprises an intermediate channel-shaped portion 12 which faces the inner backing door 5.
  • the sub-assembly 5, 11 thus formed is enamelled by known methods, and the enamel is fired in a furnace at a temperature exceeding 700°C. By previous masking, the enamel is prevented from coating the outer face of the intermediate portion 12 of the stiffening frame 11.
  • a first glass pane 12A is placed on the edge 8 after interposing a gasket 13 of heat-resistant material (for example fibreglass) which is elastically yieldable and extends along the entire periphery of the pane 12A.
  • a microwave shield 14 in the shape of a perforated thin flat metal sheet, for example of stainless steel or aluminium, and formed by punching and pressing is placed on glass pane 12A.
  • an outer backing door 16 is fastened to the stiffening frame 11 along its intermediate channel-shaped portion 12 so as to clamp the shield 14 along its periphery.
  • the outer backing door 16 is also pressed from sheet steel so as to comprise a intermediate step 20 and it then enamelled, the enamel being fired as set out in the foregoing.
  • the enamel is applied selectively so that the most inner portion 17 remains free from enamel in that zone which is opposite the base wall of the channel-shaped portion 12 and thereby the peripheral edge of the shield 14 becomes clamped between two electrically conductive surfaces.
  • the outer backing door 16 is fastened to the sub-assembly comprising the inner backing door 5 and the annular stiffening frame 11 in a manner such that the step 20 is spaced apart from the slotted side wall 6.
  • the inner side wall of the peripheral channel defined by the annular stiffening frame 11 and the outer side wall 6 is thus prolonged by the step 20 so as to constitute an effective seal for preventing microwave energy leakage from the oven cooking chamber 2 to the surrounding environment.
  • the outer backing door 16 defines a central viewing aperture 19 which is practically coaxial and equal to that of the inner backing door 5.
  • the first glass pane 12A is locked in position between the inner and outer backing doors 5, 16 by the shield 14.
  • the outer backing door 16 comprises a flat portion 21 which is parallel to the portion 17 and is followed by a groove 22.
  • the groove 22 presses against the soft part of a heat-resistant seal gasket 23 which is connected to the oven structure 1 in a position corresponding with the aperture 3 of the cooking chamber 2.
  • the groove 22 is followed by a flat portion 24 comprising bored indentations 25 which allow the fixing of conventional hinges (not shown) for connecting the door 4 is connected to the oven structure 1.
  • the outer backing door 16 terminates in a profiled side wall 26 having a bent end for supporting a second glass pane 28. This glass pane 28 is locked in position by conventional removable fasteners such as, for example a surrounding profiled section 27 which clamps the edge of the pane 28 against the bent end of the side wall 26.
  • a metal channel bar section 33 acting as spacer, is welded along its flange 35 to the front side of the outer backing door 16.
  • An angle bar frame 40 pressed from sheet metal is fastened to the channel bar section 33 by means of screws 41 so as to lock the intermediate glass pane 29 in position.
  • the frontally projecting side wall 42 of angle bar frame 40 terminates very close to the outer glass pane 28 and defines a central viewing port, which is practically coaxial and equal to the viewing apertures of the inner and outer backing doors 5, 16 and which also defines an annular chamber 50, into which heat insulating material such as rock wool is inserted.
  • the invention also covers a modification of the door 4 described in the foregoing which is suitable for a domestic oven employing microwave and resistance heating, but in which the latter is used only for cooking or heating food.
  • the maximum temperature which can exist in the oven cooking chamber 2 is 300°C, so that the oven door 4 need only offer reduced resistance to heat loss.
  • Those parts of the door 4 described which are therefore not used are: the intermediate glass pane 29, the metal channel bar frame 32 and the gasket 30.
  • the spacer section 33 and the metal angle bar frame 40 will then be of conveniently modified depth and the gaskets 13, 23 can be of neoprene rubber.
  • the constructional differences between the two door embodiments described are very limited in scope. It is therefore a basic feature of the present invention that the constituent elements, of the door 4 are optimally standardized, irrespective the type of oven for which the door 4 is intended.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electric Ovens (AREA)
  • Vending Machines For Individual Products (AREA)
EP84200916A 1983-06-30 1984-06-25 Procédé pour la fabrication des portes pour fourneaux qui combinent le chauffage à micro-ondes et à résistance électrique Withdrawn EP0131324A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT21866/83A IT1163631B (it) 1983-06-30 1983-06-30 Metodo per la costruzione di porte per forni domestici operanti a microonde e a riscaldamento resistivo e porta ottenuta
IT2186683 1983-06-30

Publications (2)

Publication Number Publication Date
EP0131324A2 true EP0131324A2 (fr) 1985-01-16
EP0131324A3 EP0131324A3 (fr) 1986-08-06

Family

ID=11187960

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84200916A Withdrawn EP0131324A3 (fr) 1983-06-30 1984-06-25 Procédé pour la fabrication des portes pour fourneaux qui combinent le chauffage à micro-ondes et à résistance électrique

Country Status (4)

Country Link
EP (1) EP0131324A3 (fr)
JP (1) JPS6023726A (fr)
ES (1) ES533760A0 (fr)
IT (1) IT1163631B (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0503899A2 (fr) * 1991-03-14 1992-09-16 Kabushiki Kaisha Toshiba Four à micro-ondes
DE4431619A1 (de) * 1994-09-05 1996-03-07 Bosch Siemens Hausgeraete Herdtür eines Kochherdes
EP1862741A2 (fr) * 2006-05-29 2007-12-05 LG Electronics Inc. Assemblage de porte pour appareil de cuisson
DE102008042468A1 (de) * 2008-09-30 2010-04-01 BSH Bosch und Siemens Hausgeräte GmbH Ofentür
WO2014114778A1 (fr) * 2013-01-25 2014-07-31 Electrolux Home Products Corporation N. V. Porte de four et châssis pour un four à micro-ondes ou pour un appareil à fonction de chauffage par micro-ondes

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4647548B2 (ja) * 2006-05-29 2011-03-09 三菱電機株式会社 高周波加熱装置

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE8235269U1 (de) * 1982-12-15 1983-06-30 Bosch-Siemens Hausgeräte GmbH, 7000 Stuttgart Backofen mit einer hochfrequenz-heizvorrichtung und mit widerstands-heizkoerpern

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE8235269U1 (de) * 1982-12-15 1983-06-30 Bosch-Siemens Hausgeräte GmbH, 7000 Stuttgart Backofen mit einer hochfrequenz-heizvorrichtung und mit widerstands-heizkoerpern

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0503899A2 (fr) * 1991-03-14 1992-09-16 Kabushiki Kaisha Toshiba Four à micro-ondes
EP0503899A3 (en) * 1991-03-14 1992-11-19 Kabushiki Kaisha Toshiba Microwave oven
DE4431619A1 (de) * 1994-09-05 1996-03-07 Bosch Siemens Hausgeraete Herdtür eines Kochherdes
EP1862741A2 (fr) * 2006-05-29 2007-12-05 LG Electronics Inc. Assemblage de porte pour appareil de cuisson
EP1862741A3 (fr) * 2006-05-29 2014-07-02 LG Electronics Inc. Assemblage de porte pour appareil de cuisson
DE102008042468A1 (de) * 2008-09-30 2010-04-01 BSH Bosch und Siemens Hausgeräte GmbH Ofentür
WO2014114778A1 (fr) * 2013-01-25 2014-07-31 Electrolux Home Products Corporation N. V. Porte de four et châssis pour un four à micro-ondes ou pour un appareil à fonction de chauffage par micro-ondes
US9750088B2 (en) 2013-01-25 2017-08-29 Electrolux Home Products Corporation N. V. Oven door and a chassis for a microwave oven or an appliance with microwave heating function

Also Published As

Publication number Publication date
IT8321866A0 (it) 1983-06-30
IT1163631B (it) 1987-04-08
ES8505079A1 (es) 1985-05-01
JPS6023726A (ja) 1985-02-06
ES533760A0 (es) 1985-05-01
EP0131324A3 (fr) 1986-08-06

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Inventor name: FIOROLI, MARIO