WO1989006928A1

WO1989006928A1 - Electrical heating apparatus

Info

Publication number: WO1989006928A1
Application number: PCT/AU1989/000024
Authority: WO
Inventors: Alec Robinson
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-01-29
Filing date: 1989-01-27
Publication date: 1989-08-10
Anticipated expiration: 1990-07-29

Abstract

An electrical heating (10) apparatus that comprises the combination of a storage unit (11) and a plurality of dismountable dish warmers (25) mounted thereon, the storage unit (11) being arranged in use to be connected to a source of electrical power, the storage unit (11) having a plurality of support means (15) in electrical connection with the source of power. The support means (15) is designed so that location of each dish warmer (25) on the support means causes the dish warmer (25) to be connected to the source of power. Each dish warmer (25) comprises a heat resistant base (28), a heat conductive top surface (27) arranged, in use, to support a dish, heat storage means (47) positioned below the top surface, and an electrical hearing element (45) positioned between the heat storage means (47) and the base (28) whereby, in use, the dish warmer (25) can be heated electrically to subsequently impart heat to a dish placed on the top surface (27).

Description

ELECTRICAL HEATING APPARATUS ^~ Field of the Invention

This invention relates to electrical heating apparatus and more particularly to apparatus that includes dish warmers that, in use, keep food or beverages warm during consumption.

- ^' Discussion of Prior Art

A problem encountered with catering on both large commercial or small domestic scales concerns keeping foodstuffs warm. Although it is desirable to preheat dishes such as plates and bowls there is still a tendency for rapid dissipation of the heat to the atmosphere.

Previous solutions to this problem have included electrically heated warming trays and cabinets that can carry the food and dishes in a warm/hot environment to the table of the diner. However, these devices do not overcome the problem of heat dissipation from the dish when placed in front of the diner. The trays or cabinets are too large for the diner to use as a place mat.

It is the above problems that have brought about the present invention.

Summary of the Invention According to the present invention there is provided an electrical heating apparatus comprising: a storage unit and a plurality of dismountable dish warmers mounted thereon, the storage unit being arranged in use to be connected to a source of electrical power, the storage unit having a plurality of support means in electrical connection with the source of power, each dish warmer comprising a heat resistant base and heat conductive upper surface with an electrical element therebetween, whereby location of each dish warmer on the support means causes the electrical element to be connected to the source of power.

In a preferred embodiment each dish warmer has a handle projecting therefrom, the handle including an ^" electrical socket coupled to the element, the handle being mountable on the support means to cause electrical contact between the power source and socket.

Preferably, the base of each dish warmer is made from moulded plastics such as polypropylene. Preferably, the top surface of each dish warmer is made from aluminium or stainless steel.

Preferably, a heat storage means or heat sink is provided between the top surface and the base of each dish warmer.

The heat sink may comprise sand, a zinc die casting or any material which effectively stores and retains heat.

According to a further aspect of the present invention there is further provided a dish warmer comprising: a heat resistant base, a heat conductive top surface arranged, in use, to support a dish, a heat storage means positioned below the top surface, and an electrical heating element positioned between the heat sink and the base whereby, in use, the dish warmer can be heated electrically to subsequently impart heat to a dish placed on the top surface .

Description of the Drawings

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a perspective view of an electrical heating apparatus ;

Figure 2 is a perspective view of a dish warmer;

Figure 3 is a sectional view of the dish warmer taken along the lines 3-3 of Figure 2; and Figure 4 is a plan view of the dish warmer without its top surface, showing an electrical heating element. Preferred Embodiment

As shown in Figure 1 of the accompanying drawings, a heating apparatus 10 comprises a storage unit 11 in the form of an open box having a base 12 and vertically projecting side walls 13. A plurality of plate-shaped dish warmers 25 are supported upright in parallel rows by combined support/switch assemblies 15. The combined support/switch assemblies are furnished on two ribs 14 spaced in parallel alignment on the base 12 of the unit 11. Three spring loaded switch assemblies 15 are spaced along each rib 14. Each switch assembly 15 is adapted to make electrical contact between an electrical power source (not shown) and a dish warmer 25. The switch assembly 15 as shown in Figure 4 comprises a spigot 16 which protrudes vertically from the rib 14. A cylindrical sleeve 17 is slidable within a nylon sleeve 18 which lines a bore 19 of the spigot 16. The cylindrical sleeve 17 has a conductive pin 20 projecting therefrom which is adapted to be received by an electrical contact socket 44 of a dish warmer 25. A spring 21 is placed within the nylon sleeve 18 so that when a force is applied to the pin 20 to cause the sleeve 17 to slide within the bore 19 towards the spring 21, the spring 21 is compressed, thus enabling contact between the conductive pin 20 and an electrical contact 20a at the base of the bore 19. Each switch assembly is wired to an entry lead 50 which can be coupled to a mains A.C. supply.

As shown in Figures 2 to 4, a dish warmer 25 comprises a plate shaped body 26 having a heat conductive top surface 27, of aluminium or stainless steel, and a heat resistant base 28 made from moulded plastics, such as polypropylene. The base 28 may have small legs protruding therefrom. The top surface 27 has an annular rim 35 extending around its periphery which is secured to an annular wall 29 extending upwardly from the base 28, by stainless steel screws 30. The rim 35 aids in locating an article, such as a plate 31, which is placed on the warmer 10.

The base 28 also includes heat resistant handles 40 and 41 that extend outwardly from opposite ends of the warmer. One of the handles 40 has a cylindrical bore 43 within which is located the electrical contact socket 44. The socket 44 is connected to an electrical heating element 45. The heating element 45 can be calibrated by selecting its resistance and/or length so that when supplied with electricity, the heating element 45 will heat to a predetermined temperature. The heating element 45 is located within the body of warmer 25 to define a first cavity 51 between the underside of the element 45 and the base 28 and a second cavity 52 between the upper surface of the element and the underside of the heat conductive top 27. Two leveller plugs 42 are provided on each side of the element to keep the heating element, 45 horizontal. A heat sink 47 in the form of a zinc heat retention plate, is positioned between the top surface 27 and the heating element 45 within the second cavity 52.

The base of the first cavity 51 is given a reflective coating to reflect heat radiating from the underside of the element upwardly and away from the heat resistant base 28. The cavities 51 and 52 which are preferably air filled or alternatively may be filled with sand to cause the heat in the element to dissipate slowly to the heat conductive top surface 27. The heat sink 47 retains the heat to continue and maintain the dissipation referred to above. The polypropylene base 28 is heat-resistant to ensure minimal heat absorption by the base 28 and consequential damage to the surface on which the warmer 25 is placed. Although in the preferred embodiment a separate die cast zinc heat sink 45 is used, it is understood that the heat sink can take many forms and be made of a variety of materials. For instance the top surface 27 may include a substantially thick base of aluminium or cast iron to act as the heat sink.

The storage unit 11 acts both as a support means for the warmers and a source of electrical power to heat the dish warmers 25 to the desired temperature whilst being stored in upright rows in the unit 11.

The dish warmer 25 is positioned over a support/switch assembly so that the pin 20 and the sleeve 17 are received in the bore 43 of the handle 40. The sleeve 17 is longer than the distance between the socket 44 and the other end 61 of the bore 43 in the handle 40, thus when the handle 40 abuts the spigot 16, after the pin 20 and the sleeve 17 have been inserted into the bore 43 of the handle 40, the sleeve 17 is forced into the bore 19 of the spigot 16 to cause the spring 21 to be compressed. As a result, electrical contact is made between the power source,, and the contact socket 44 of the heating element 45. It is understood that the support for the dish warmers 25 could be strengthened to provide a more positive support for each warmer 25 whilst at the same time providing direct electrical contact between the base and the warmer. Although not shown in the drawings the storage unit is provided with an on/off switch to allow adjustability of ^'the temperature of the warmers, and a heat regulator which controls the current to the element. A suitable electrical cut-out is provided to ensure that the dish warmers do not overheat.

A ring 55 (shown in Figure 1 only) is pivotally connected to the handle 41 so that the heated dish warmer 25 can be easily lifted from the unit 11 to disengage the warmer 25 from the spring loaded switch assembly 15. In use, the unit 11 loaded with the dish warmers 25, is located in a convenient position, for example on a bench top in a kitchen or a sideboard in a dining room, and is switched on so that the dish warmers are heated to the selected temperature.

When a meal is about to be presented to a diner, a dish warmer 25 is removed from the unit 11 and placed on the table in front of the diner. When the dish warmer 25 is removed from the unit 11, the heating element 45 is no longer energized by the power source, since the contact between the element 45 and the power source has been disconnected. The diner's meal, preferably on a preheated plate, is positioned on the dish warmer 25 such that the plate is in contact with the top surface 27 of the dish warmer 25. The rim 35 of the top surface 27 assists the positioning of the plate and preventing it from accidental displacement from the warmer 25. The heat sink 47 gradually releases heat through the top surface 27 to the plate. In practice, it has been found that such heat transfer is able to maintain the plate, and the food on the plate, at a desired temperature for 20 to 30 minutes, sufficient time for a leisurely meal.

Once the diner has finished the meal, the plate and the dish warmer 25 are removed from the table and the dish warmer 25 can be stacked with other used dish warmers 25 for cleaning and return to the storage unit. The dish warmers 25 are stored in engagement with their respective spring loaded switch assemblies 15 in the storage unit 11, while the power source is not activated. A cover (not shown) can be used to close the storage unit 11. The apparatus described above provides a compact means of preheating a dish warmer that doubles as a plate mat thereby ensuring that heat stored within the dish warmer dissipates through the dish thereon to keep food warm whilst the food is consumed.

It is to be understood that a smaller version of the device could be adapted for keeping beverages in cups or mugs warm. It is further understood that the apparatus could be designed to be much larger for catering use with three or four rows of up to ten dish warmers in a single unit.

Further modifications include selecting the contour of the top surface of the dish warmers to suit other shapes of dishes such as bowls or turins. Although in the preferred embodiment the dish warmers are mounted upright on the support unit, it is understood that the base unit could be designed to accommodate the dish warmers in horizontal arrays.

Many modifications within the spirit of the invention including the choice of materials and the selection of the electrical parameters depending on the availability of electrical power, costs of materials and weight and aesthetics of the final product.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. An electrical heating apparatus comprising: a storage unit and a plurality of dismountable dish warmers mounted thereon, the storage unit being arranged in use to be connected to a source of electrical 5 power, the storage unit having a plurality of support means in electrical connection with the source of power, each dish warmer comprising a heat resistant base and heat conductive upper surface with an electrical 10 element therebetween, whereby location of each dish warmer on the support means causes the electrical element to be connected to the source of power.

2. An electrical heating apparatus according to Claim 1, wherein each dish warmer has a handle projecting therefrom, the handle including an electrical socket coupled to the element, the handle being mountable on the

5 support means to cause electrical contact between the power source and socket.

3. An electrical heating apparatus according to Claim 2, wherein the dish warmers rest upright on the support means in parallel arrays when mounted on the storage unit.

4. An electrical heating apparatus according to Claim 3, wherein the support means comprising spigots extending upwardly from the storage unit, each spigot having an electrical pin projecting therefrom for

^~ engagement with the socket within the handle on dish warmer.

5. The apparatus according to any one of the preceding claims, wherein the heat-resistant base of the dish warmer is made from moulded plastics, such as polypropylene. 6. The apparatus according to any one of the preceding claims, wherein the top surface of the dish warmer is made from aluminium or stainless steel.

7. The apparatus according to any one of the preceding claims, wherein the top surface has an upwardly projecting rim extending around the periphery of the top surface.

8. The apparatus according to any one of the preceding claims, wherein a heat storage means is provided between the top surface and the heating element.

9. The apparatus according to Claim 8, wherein the heat storage means is sand or a zinc die casting.

10. A dish warmer comprising: a heat resistant base, a heat conductive top surface arranged, in use, to support a dish, heat storage means positioned below the top surface, and an electrical heating element positioned between the heat storage means and the base whereby, in use, the dish warmer can be heated electrically to subsequently impart heat to a dish placed on the top surface.

11. A dish warmer according to Claim 10, wherein a handle projects outwardly from the base, the handle including an electrical socket to facilitate connection in use to a source of power.

12. The dish warmer according to either Claims 10 or 11, wherein the base is made from moulded plastics such as polypropylene.

13. The dish warmer according to any one of Claims 10 to 12, wherein the top surface has an upwardly projecting rim extending around the periphery of the top surface.

14. A dish warmer according to any one of Claims 10 to 13, wherein the top surface is made from aluminium or stainless steel. ls. The dish warmer according to any one of Claims 10 to 14, wherein the heat storage means is sand or a zinc die casting.

16. An electrical heating apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

17. A dish warmer substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.