EP0174732B1 - Four à micro-ondes - Google Patents

Four à micro-ondes Download PDF

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Publication number
EP0174732B1
EP0174732B1 EP19850305591 EP85305591A EP0174732B1 EP 0174732 B1 EP0174732 B1 EP 0174732B1 EP 19850305591 EP19850305591 EP 19850305591 EP 85305591 A EP85305591 A EP 85305591A EP 0174732 B1 EP0174732 B1 EP 0174732B1
Authority
EP
European Patent Office
Prior art keywords
cavity
tray
microwave oven
power
microwave
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.)
Expired
Application number
EP19850305591
Other languages
German (de)
English (en)
Other versions
EP0174732A1 (fr
Inventor
Kenneth Ian Eke
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.)
Microwave Ovens Ltd
Original Assignee
Microwave Ovens Ltd
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
Priority claimed from GB848420608A external-priority patent/GB8420608D0/en
Priority claimed from GB858513537A external-priority patent/GB8513537D0/en
Application filed by Microwave Ovens Ltd filed Critical Microwave Ovens Ltd
Publication of EP0174732A1 publication Critical patent/EP0174732A1/fr
Application granted granted Critical
Publication of EP0174732B1 publication Critical patent/EP0174732B1/fr
Expired 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
    • H05B6/647—Aspects related to microwave heating combined with other heating techniques
    • H05B6/6473—Aspects related to microwave heating combined with other heating techniques combined with convection heating
    • 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
    • H05B6/6408—Supports or covers specially adapted for use in microwave heating apparatus
    • H05B6/6411—Supports or covers specially adapted for use in microwave heating apparatus the supports being rotated

Definitions

  • This invention relates to a microwave oven with means for launching microwave power into a cavity of the oven from a launch area in the base of the cavity.
  • microwave power is transferred from a magnetron to the oven cavity in dependence upon the effectiveness of the coupling between the load of the oven cavity and the magnetron.
  • microwave ovens have been designed to achieve optimum coupling for a wide range of loads corresponding to differing sizes and densities of food items placed in the cavity. This optimisation of coupling means that for a given input power to the magnetron the power into the cavity is optmised over the range of loads placed in the oven cavity.
  • the invention adopts an entirely different approach by aiming to provide a microwave oven having a cavity which, when devoid of food, is a poor power match with the magnetron, with the result that the amount of power transferred from the magnetron to the food being cooked is dependent almost entirely on the load of the food item.
  • DE-B-1151611 discloses a microwave oven comprising a magnetron for producing microwave power to be delivered into the cavity of the oven, means for launching the microwave power into the cavity from a launch area, and a metal member supported in the cavity in front of the launch area so that the oven when devoid of food provides an inefficient power match with the magnetron.
  • FR A 2310058 discloses a microwave oven with means for launching microwave power into the oven cavity through the base of the cavity, but does not disclose a metal tray supported above the launch area, which is essential to the present invention.
  • a microwave oven comprises a magnetron for producing microwave power to be delivered into the cavity of the oven, means for launching the microwave power into the cavity- from ⁇ - launch area, a metal member supported in the cavity facing the launch area so that the oven when devoid of food provides an inefficient power match with the magnetron, characterized in that the oven has a power rating within the power limitations of a domestic plug/ socket, the launch area is in the base of the cavity, the member is a tray made of sheet metal with the peripheral edge of the tray spaced from the cavity walls and the metal tray is above the launch area, so that when food items are placed on said tray the resulting dielectric load determines the power coupled to the loaded oven from the magnetron.
  • the amount of microwave power coupled into a loaded oven is substantially proportional to the dielectric load.
  • the microwave oven need not have selectable microwave power settings which the user must first preset, because the load of the food item itself determines the amount of power delivered by the magnetron to the loaded cavity.
  • the tray may be circular and may form a rotatable turntable on which the food items are supported during cooking.
  • the turntable is preferably driven by a rotatable drive member extending upwardly through the base of the cavity, and this drive member may be arranged concentrically with a further drive member which rotates a mode stirrer in the base.
  • the positioning and size of the tray in the cavity are important factors in ensuring that the tray presents a load which is a poor match for the magnetron in terms of effectiveness of power transfer from the magnetron to the oven cavity.
  • the tray is between 18 and 25 mm (preferably about 20 mm) above the base, and is between 350 and 380 mm in diameter, preferably about 360 mm.
  • the tray will normally be made of sheet metal, which may be stove enamelled.
  • the oven preferably has thermal heating means in addition to the magnetron, the thermal heating means providing a forced flow of hot air through the cavity, as a result of air being blown over an electrical resistance heating element by means of a fan.
  • the air flow pattern is preferably such that hot air is forced into the cavity through an inlet in a rear wall of the cavity, and leaves the cavity through an outlet in the rear wall.
  • the back wall may have two inlets for the entry of forced hot air and two outlets for the exit of forced hot air.
  • the oven may be a small, portable microwave oven.
  • the oven is a small table top oven powered from a domestic plug/socket.
  • the oven is generally rectangular in shape and the cavity is defined by two side walls 2, 4, a back wall 6, a top panel 8 and a base panel 10.
  • Microwave power is launched into the cavity through a rectangular aperture 12 in the base panel 10.
  • a mode stirrer (not shown) is mounted in the aperture 12 and is rotatably driven about a vertical axis.
  • the cavity accommodates a removable turntable in the form of a metal tray 14.
  • the tray 14 has a circular base 360 mm in diameter, surrounded by an upstanding wall or rim 25 mm high.
  • the tray 14 is formed of sheet metal which may be stove enamelled.
  • the cavity may have a height of 230 mm, a width of 400 mm and a depth of 390 mm.
  • the tray 14 is spaced 20 mm above the base panel 10, and the underside of the tray 14 is engaged by rollers 16 which are mounted on the base panel 10.
  • Drive means for rotating the turntable extend upwardly through the aperture 12 and are shown diagrammatically at 18.
  • Such drive means are coaxially arranged with the drive to the mode stirrer, for example by the turntable being rotatably driven by a central vertical shaft surrounded by a drive sleeve driving the mode stirrer.
  • the drive shaft and drive sleeve are driven at their appropriate speeds, eg by belt drives from a motor. It will be appreciated that all this structure, together with a magnetron for delivering the microwave power, will be positioned below the cavity but within the oven outer casing which is not shown in the drawings.
  • FIG. 2 shows the hot air inlet and outlet in the back wall 6, as the latter is viewed from the front of the oven.
  • the back wall 6 has a vertically elongated inlet 20 through which hot air is forced by a fan to enter the cavity. Having passed over the food items, the air leaves the cavity through the circular air outlet 22. The air is then forced over an electric resistance heating element (disposed in a compartment behind the rear wall 6) before being recirculated through the inlet 20 and the cavity.
  • the turntable rotates about a central vertical axis, the underside of the tray 14 engaging the rollers 16.
  • the oven walls may be made of a single thickness of metal, so reducing construction costs and weight.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Constitution Of High-Frequency Heating (AREA)

Claims (9)

1. Four à micro-ondes comprenant un magnétron pour produire de la puissance micro-ondes destinée à être délivrée à l'intérieur de la cavité d'un four, des moyens pour générer la puissance micro-ondes à l'intérieur de la cavité à partir d'une zone de génération, un élément métallique supporté dans la cavité, faisant face à la zone de génération, de sorte que le four, quand il est vide de nourriture, fournit un couplage en puissance inefficace avec le magnétron, caractérisé en ce que le four a un régime nominal de fonctionnement en puissance compris dans les limitations de puissance d'une prise douille domestique, la zone de génération 12 est située dans la base de la cavité, l'élément est un plateau (14) fait d'une feuille métallique avec la côté périphérique du plateau espacé des parois de la cavité et le plateau métallique (14) est au-dessus de la zone de génération (12), de sorte que lorsque les éléments de nourriture sont placés sur ledit plateau, la charge diélectrique résultante détermine la puissance couplée au four chargé à partir du magnétron.
2. Four à micro-ondes selon la revendication 1, caractérisé en ce que le plateau (14) est circulaire et forme un plateau tournant rotatif sur lequel les éléments de nourriture sont supportés et mis en rotation pendant la cuisson.
3. Four à micro-ondes selon la revendication 2, caractérisé en ce que le plateau tournant est actionné par un élément actionneur rotatif (18) s'étendant vers le haut au travers de la base de la cavité.
4. Four à micro-ondes selon la revendication 3, caractérisé en ce que ledit élément actionneur est agencé concentriquement avec un élément actionneur supplémentaire qui fait tourner un excitateur de modes dans la phase de la cavité.
5. Four à micro-ondes selon l'une quelconque des revendications 2 à 4, caractérisé en ce que le plateau est entre 18 et 25 mm au-dessus de la base, et a un diamètre entre 350 et 380 mm.
6. Four à micro-ondes selon l'une quelconque des revendications précédentes, caractérisé en ce que le plateau est une feuille métallique dont la surface externe est émaillée au four.
7. Four à micro-ondes selon l'une quelconque des revendications précédentes, caractérisé en ce que le four a des moyens de chauffage thermique en plus du magnétron, les moyens de chauffage thermique fournissant un courant d'air chaud forcé au travers de la cavité, comme résultat d'un air-soufflé sur un élément de chauffage à résistance électrique, au moyen d'un ventilateur.
8. Four à micro-ondes selon la revendication 7, caractérisé en ce que l'air chaud est dirigé de façon forcée dans la cavité au travers d'une ouverture (20) d'entrée dans la paroi arrière de la cavité, et quitte la cavité au travers d'une ouverture de sortie (22) dans la paroi arrière de la cavité.
9. Four à micro-ondes selon la revendication 7, caractérisé en ce que la configuration du courant d'air est telle que l'air chaud est dirigé de façon forcée à l'intérieur de la cavité au travers de deux ouvertures d'entrée dans la paroi arrière de la cavité, et quitte la cavité au travers de deux ouvertures de sortie dans la paroi arrière.
EP19850305591 1984-08-14 1985-08-06 Four à micro-ondes Expired EP0174732B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB8420608 1984-08-14
GB848420608A GB8420608D0 (en) 1984-08-14 1984-08-14 Microwave oven
GB8513537 1985-05-29
GB858513537A GB8513537D0 (en) 1985-05-29 1985-05-29 Microwave oven

Publications (2)

Publication Number Publication Date
EP0174732A1 EP0174732A1 (fr) 1986-03-19
EP0174732B1 true EP0174732B1 (fr) 1989-11-08

Family

ID=26288117

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19850305591 Expired EP0174732B1 (fr) 1984-08-14 1985-08-06 Four à micro-ondes

Country Status (2)

Country Link
EP (1) EP0174732B1 (fr)
DE (1) DE3574220D1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR930005040B1 (ko) * 1989-08-31 1993-06-12 주식회사 금성사 식기 건조기 겸용 전자레인지 및 그 구동제어방법
JPH11111447A (ja) * 1997-09-29 1999-04-23 Samsung Electron Co Ltd １つのモータによって駆動されるスタラー及びトレーを備えた電子レンジ
US11412584B2 (en) 2017-12-08 2022-08-09 Alkar-Rapidpak, Inc. Ovens with metallic belts and microwave launch box assemblies for processing food products

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH433536A (de) * 1964-07-08 1967-04-15 Z Elektrotepelnych Zarizeni Ze Einrichtung für die dielektrische Erwärmung elektrisch nichtleitender Stoffe unter Ausnützung von Mikrowellenenergie
US4121078A (en) * 1975-04-30 1978-10-17 Matsushita Electric Industrial Co., Ltd. Microwave heating apparatus
US4337384A (en) * 1979-08-01 1982-06-29 Matsushita Electric Industrial Co., Ltd. Cooking appliance of the hot air circulating type
JPS56149531A (en) * 1980-04-22 1981-11-19 Sharp Corp Hot-air circulation type cooker
GB2127658B (en) * 1982-07-17 1986-01-29 Microwave Ovens Ltd Microwave ovens and methods of cooking food

Also Published As

Publication number Publication date
EP0174732A1 (fr) 1986-03-19
DE3574220D1 (en) 1989-12-14

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