GB2274567A

GB2274567A - Microwavable heating device

Info

Publication number: GB2274567A
Application number: GB9301102A
Authority: GB
Inventors: Colin Michael Clifford
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-01-21
Filing date: 1993-01-21
Publication date: 1994-07-27
Also published as: GB9301102D0; WO1994017646A1; AU5704994A

Abstract

A portable source of heat is made by using a core material that contain varying ammounts of minerals which are activated by the microwave energy. A ceramic tile 23 can be bonded direct to the core 21 and the whole unit is moulded into a resin and filler mix 22 the tile been on the outside this acts like a hot-plate absorbing the heat from the core while the resin mix insulates. A liquid flow pipe 43 can extend through the core to heat a liquid. Alternatively the core may be totally enclosed by the resin and filler mix. <IMAGE>

Description

MICROWAVABLE HEATING DEVICE.

This invention concerns the use of a microwavable heating device to provide a useful souce of energy.

Specifically. this invention relates to a microwavable heating device for use in heating food or keeping food warm.

Present divices for heating food may comprise a grill with candles lit underneath on which are placed the items to he kept warm. However. this arrangement has the disadvantage that the candles must be lit and replaced and there are some situations where a naked flame is not advisable.

A hotplate may also be used at present to keep food warm. In this arranaement the food or other items to be kept warm are placed on a ceramic top which has an element within it which is plugged into an electricity and also results in unsightly power leads.

This present invention seeks to provide a microwavable heating apparatus which is easy and simple to use, portable, and which uses microwave energy, is efficient and cheap.

According to this invention there is provided a microwavable heating device including a first or third component which converts microwave energy into heat, a second component to allow the transfer of heat,and the third component also acting to to insulate both first and second component's.

This arrangement enables part of the external surfaces to be maintained at a relatively cool temperature, enabling the device to be handled easily.while providing a source of heat through the second surface region.

In a preferred arrangement the first component or the microwavable heating device would contain varying ammounts of minerals.

This enables the first surface region to become hotter more easily.

Furthermore, the second surface region of the microwavable heating device may be glazed or unglazed.

This enables the second surface to radiate heat stored in the first surface region.

Additionally the microwavable heating device may have a core formed from the first component. and an insulating material around the core with the second surface region being located outwardly of the insulating material.

Preferably the insulating material is porous. This allows the microwave energy to pass more treely to the first surface region.

For a better understanding of the present invention, and to show how it may be brought into effect, reference will now be made. by way of example, to the drawings, in which: Figure 1 shows a plan view of a microwave heating device according to the invention.

Figure 2 shows a crosssection through line A-A in Figure 1: Figure 3 is a plan view of a heating device in accordance with a further alternative embodiment of the invention; and Figure 4 is a crosssection through the device Figure 5. shows a further alternative with the core material as the heating surface.

Figure 6. yet another device with the core material been completely surrounded by the insulating material and having no visible heating surface.

shown in Figure 4.

The microwave heating device comprises a microwave activated core. This core is made out of a material suitable for converting microwave energy into heat.

For example. the core may be made from any fired clay. This material is typically a mixture of silica, alumina and ferric oxide. plus other components present in small amounts. It will be apparent that other materials could be used for this purpose. Provided that the device includes a component capable of convertinq microwave energy to heat. the core may be made of a material which is unaffected by microwave energy. but which has a large heat capacity and can be heated indirectly by the microwave energy.

The core 1 is partially surrounded by a moulded insulating material 3. This insulating material is preferably made out of a porous material. The edaes of the material are preferably left untlazed.

although they may be coated with an acrylic-based material. The use of a porous insulating material 3 with unglazed surfaces means that heat can easily escape from the insulating material and hence that its surfaces remain relatively cool since air and moisture can escape there from.

The moulded material material may in particular be made from binding Polyurethane resins. toaether with suitable fillers such as refined flash' having a specific gravity of bewteen 0.4 to 0.7.

The resin and the filler are present in the ratio approximately 1:4. i.e. approximately 25t) grams of the Resin to 2.4 litres app lkg of ash or other non- absorbing filler.

This material may be easily moulded into the desired shape for the insulating means. In particular the material may be moulded so that it is easy to handle. Moulding is carried out bv packing the mixture of resin and filler into a mould and compressing it, either by hand or by machine. The mould can then be lifted off the moulded product.

The grains of ash are each similar to a microsphere containing a small amount of gas, which becomes hot when exposed to microwave energy. In addition.

because of the relatively small proportion of the resin which is used. compared to most moulding materials, the gaps between the grains of the filler are left . unfilled. This means that air.

moisture and microwaes can pass freely through the material.

Moreover. this material has the advantage that it is a aood insulator. and is resistant to heat.

including temperatures of at least 150c. As a result, it is able to withstand being in contact with the hot core without damage. and without becoming too hot to handle.

The core material has a surface which is intended to provide the heating surface. This surface may be flat. If the heating device is to be used for keepina plates and food warm a protective tile 2 may be placed in thermal contact with the core matrial. The tile 2 may advantageously be made from a ceramic material, and have a glazed surface 3a.

This tile might rest upon the moulded material for support. or sit directly on the core.

However. a heating device in accordance with the invention may be used for purposes other than warming plates or food, for example a t^rttle warmer, and in this case the core and surrounding moulding material will be suitahly shaped. In addition the heating device may also be used in other heating situations. and the shape clef: the heating surface together with the dimensions of the device. may be chosen in accordance with the intended use of the device.

Alternatively, the porous insulating may be saturated, or substantially saturated. with water before the device is exposed to the microwave energy.

The apparatus may be removed from the microwave oven and used in the desired manner.

After microwaving the core will retain its heat and provide heat through the heat conductina material.

However the insulating material will cool rapidly due to the porosity and the evopration of the moisture, this will make it easy to handle.

Figure 2 is a cross section through the device 20 in accordance with the invention This device has a core 21 surrounded by an insulating material 22 and a heating surface 23. This device may be used without the addition of water.

Figures 3 and 4 show an alternative device 40 having a core 41. and an outer layer of insulating material 42. this device has an internal in the form of a tube 43. for example made of glass.and connected to other pipes. a liquid is pumped round the system while been heated by the microwaves.

figure 5. shows a further alternative 30 showing the core material protruding from the insulating material 32. and acting as the heating surface.

figure 6. shows yet a further alternative 50. with the core 51. material surrounded by the insulating material 52. this device would allow the heat to escape only through the pores of the insulating material, giving a lower heat over a longer perlc4.

Figure 3 is a cross-section through an alternative device 20 in accordance with the invention. This device has a core 21, a layer of insulating material 22 surrounding most of the core, and a heating surface 23.

This device may be used without addition of water. or alternatively the insulating material may be saturated with water to speed up the rate at which the device is heated when exposed to microwave energy.

Figures 4 and 5 show a futher alternative device 40, having a core 41 and an outer layer of insulating material 42. This device has an internal surface in the form of a tube 43. for example made of glass. The device can be heated by exposure to microwave energy and can then be used to heat a liquid flowing through the tube 43, which can of course be connected to other liquid-containinq pipes. Meanwhile the outer surface of the insulating material 42 remains relatively cool There is thus provided a convenient source of heat for use, for example, as a food warmer.

Claims

1. A microwavable heating device including a first component which converts microwave energy into heat and having second and third components the first component becoming hotter than the second when the device is exposed to microwave energy.

2. A microwavable heating device as claimed in claim 1, wherein the first component is glazed.

3. A microwavable heating device as claimed in claim 1 or 2, wherein the second component is unglazed.

4. A microwavable heating device as claimed in claim 1. 2 or 3. having a core formed from the first component, the third component been insulating material around the core with the second component being located outwardly of the insulating material.

5. A microwavable heating device as claimed in claim 1, 2. 3. or 4, having only a first and third component.

6. A microwavable heating device as claimed in claim 5, when dependent on claim 4 wherin thee insulating material is porous.

7. A microwavable heating device. the only component been the insulating moulded material 8. A microwavable heating device as claimed in claim 4. or clai;m 5, 6 or 7 when dependent on claim ~ 4, wherein the insulating means is made of a moulded polymer.

9. A microwavable heating device as claimed in claim 7,and 8. wherein the insulating means is made from a moulded polyurethane resin using a refined fly ash filler.

11. A microwaable heating device as claimed in any preceding claim wherein the first surface region is flat.

12. A microwavable heating device as claimed in claim 11 wherein the first surface region is covered by a protective means.

13. A microwavable heating device as claimed in claim 12 wherein the protective means is made from glazed ceramic.

14 . A microwavable heating device, for warminq products,other than food 15. A microwavable heating device as claimed in any preceding claim for heating or warming food.

16. A microwavable heating device substantially as herein described with reference to Figures 1 and 2.

or figure 3 or Figure 4 or figures 5 and 6 of the accompanying drawings.