GB2171580A

GB2171580A - Stand for use in a microwave oven

Info

Publication number: GB2171580A
Application number: GB08603436A
Authority: GB
Inventors: Kenneth Ian Eke
Original assignee: Microwave Ovens Ltd
Current assignee: Microwave Ovens Ltd
Priority date: 1985-02-19
Filing date: 1986-02-12
Publication date: 1986-08-28
Also published as: GB8603436D0; GB2171580B

Abstract

A stand (24) for use in the cavity of a microwave oven has a metal body with a wire rack (26) and three legs (28) which support the stand on a rotating turntable (10). An insulating sheet (30) is placed on top of the wire rack (26) and acts to space a metal food container (34) from the metal of the stand (24) to prevent arcing or sparking therebetween. Preferably the sheet is a mesh of porcelain or PTFE to allow air to be passed through it by a hot air blower. <IMAGE>

Description

SPECIFICATION Microwave ovens and methods of cooking food Field of the Invention This invention relates generally to microwave ovens, and in particular to a stand for supporting a food container in a microwave oven. The invention also concerns a method of cooking food in a microwave oven.

Background to the Invention When a food container of metal is placed in proximity to metal in a microwave oven, sparking or arcing tends to occur between the container and the adjacent metal. Hence, if a metal container is placed on a metal stand (whether a tray, rack or turntable), in a microwave oven, sparking frequently occurs, resulting in wastage of energy and the generation of hot spots in the region of sparking. Forthis reason, many food containers for use in microwave ovens are of non-metallic materials, eg ceramic. However it is sometimes more convenient to use metal containers, for example when defrosting or cooking a food item packaged in a metal container. The invention aims to overcome the problem of sparking between metal containers and adjacent metal surfaces in microwave ovens.

Summary of the Invention According to the invention, a microwave oven comprises a stand for supporting a metal food container in a cavity of the oven, the stand comprising a metal body provided with separating means which are heat resistant, do not absorb microwave energy and which act to separate the metal body of the stand from the metal container placed thereon to prevent sparking between the metal body and the metal container.

According to another aspect of the invention, there is provided a method of cooking food in a microwave oven, wherein the food is in a metal container, comprising placing the container on a stand in a cavity of the oven and introducing microwave power into the cavity, the stand including a metal body and separating means which are heat resistant, do not absorb microwave energy and which act to separate the metal body of the stand from the metal container placed thereon to prevent sparking between the metal body and the metal container.

The separating means are preferably such as to space the metal container above the metal body by a distance which avoids sparking or arcing. The separating means may be a separate sheet of a suitable synthetic material, and in the preferred embodiment to be described the sheet has a series of apertures for the passage of hot air which is blown through the oven cavity. The sheet may be circular and each aperture may be of similar shape, eg hexagonal or circular.

Alternatively, the separating means may be formed by a coating of a suitable material on the metal body.

The separating means may be made of porcelain, polytetraflouroethylene (PTFE) or any other suitable non-metallic material which is both heat resistant and has dielectric properties such that substantially no microwave energy is absorbed by the material.

The stand may be arranged to form part of, or be supported on, a rotatable turntable, or may be a non-rotating rack or shelf.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a turntable, trivet, stand and separator made in accordance with the invention, Figure 2 shows the separator alone, and Figure 3 is a sectional view of the turntable, trivet, stand and separator.

Detailed Description of the Drawings The circular turntable 10 is a conventional metal turntable having a dished base 12, an upstanding rim 14, and a centrai formation 16 (Figure 3) which is shaped to engage with rotary drive means in the base of the microwave oven to enabletheturntable 10 to be rotated.

The trivet 18 comprises a slightly dished, circular metal panel 20 having circular perforations sufficiently closely spaced to prevent the passage of microwave energy through the panel. The trivet 18 and the turntable 10 are each stove enamelled. A peripheral edge 22 of the panel 20 rests on the rim 14 of the turntable 10.when the trivet 18 is placed in position on the turntable 10 (Figure 1).

Above the trivet 18 there is arranged a stand 24 having a metal body comprising a top in the form of a wire rack 26 and three legs 28 which rest on the panel 20 so as to support the rack 26 in spaced relationship above the trivet 18.

The oven is similar to that disclosed in our UK Patent Application No. 2127658, and is designed to be powered from a domestic plug/socket. The oven has a magnetron for delivering microwave energy into the cavity, as well as an electrical resistance heating element and fan both located behind an apertured rear wall of the cavity. The fan circulates air over the heating element and through the cavity, and thus food in the cavity is subjected to simultaneous microwave power and recirculated hot air, which together cook and brown the food as the latter is rotated.

In accordance with the invention, a separator 30 is placed on the wire rack 26.

The separator 30 is an-apertured disc of a synthetic plastics material which is heat resistant and substantially transparent to microwave energy.

The separator 30 acts to space a metal food container 34 (Figure 3) from the metal body of the stand 24 to prevent sparking therebetween. The separator 30 has a honeycomb-pattern web forming a plurality of hexagonal apertures 32 (Figure 2). The hexagonal apertures 32 in the separator 30 allow hot air to reach the base of the metal food container 34 during cooking of the food, and each aperture has a width, measured between any two opposite corners of the hexagon of 38 mm.

Instead of the separator 30, the stand 24 may be made so that the wire rack 26 is replaced by an upper disc like the separator 30. The result would be as shown in Figure 1,exceptthatthewire rack26 would be omitted and the separator would be an integral part of the stand 24.

As a further alternative to the separator 30, two or more of the wires of the rack 26 may be surrounded with sleeves of electrically insulating material such as polytetrafluoroethylene.

Claims

1. A microwave oven comprising a stand for supporting a metal food container in a cavity of the oven, the stand comprising a metal body provided with separating means which are heat resistant, do not absorb microwave energy and which act to separate the metal body of the stand from the metal container placed thereon to prevent sparking between the metal body and the metal container.

2. A microwave oven according to claim 1, wherein the separating means space the metal container above the metal body by a distance which avoids sparking.

3. A microwave oven according to claim 2, wherein the separating means comprise a sheet of synthetic material, separate from the metal body of the stand, the sheet being placed on top of the metal body to space the metal container from the metal body.

4. A microwave oven according to claim 3, wherein the separate sheet has a plurality of apertures for the passage of hot air.

5. A microwave oven according to claim 4, wherein the apertures are of the same shape.

6. A microwave oven according to claim 5, wherein the apertures are hexagonal or circular.

7. A microwave oven according to any of claims 3 to 6, wherein the metal stand and the separate sheet are circular in plan view, and the oven has a rotatable turntable on which the metal stand and separate sheet are supported.

8. A microwave oven according to claim 1 or 2, wherein the separating means are formed by a coating of an electrically insulating material on the metal body.

9. A method of cooking food in a microwave oven, wherein the food is in a metal container, comprising placing the container on a stand in a cavity of the oven and introducing microwave power into the cavity, the stand including a metal body and separating means which are heat resistant, do not absorb microwave energy and which act to separate the metal body of the stand from the metal container placed thereon to prevent sparking between the metal body and the metal container.

10. A method according to claim 9, wherein the separating means are a sheet of electrically insulating material which is formed with a plurality of apertures, and hot air is forced through the oven cavity simultaneously with the production of microwave power, the hot air being blown through the apertures in the sheet.

11. A method according to claim 9 or 10, wherein the food is placed in the metal container immediately prior to cooking in the microwave oven.

12. A method according to claim 9 or 10, wherein the food is frozen in the container and the latter is placed in the microwave oven to defrost and then cook the food in the container.

13. A microwave oven having a stand constructed and arranged substantially as herein particularly described with reference to the accompanying drawings.

14. A method of cooking food, substantially as herein particularly described with reference to the accompanying drawings.